12 1

Victor S FrostDan F Servey Distinguished Professor Electrical Engineering and Computer

ScienceUniversity of Kansas2335 Irving Hill Dr

Lawrence Kansas 66045Phone (785) 864-4833 FAX(785) 864-

7789 e-mail frosteecskuedu

httpwwwittckuedu

Specific Systems

CellularPart 112

All material copyright 2006Victor S Frost All Rights Reserved

12 2

Outline

bull Part 1ndash Basic componentsndash 3G ndash Overview of W-CDMAUMTSndash HSPDA

bull Part 2ndash EV-DO overviewndash Case study Mitigating scheduler-

induced starvation in 3G wireless networks

12 3

AC = authentication center BSS = base station subsystem EIR = equipment identity register HLR = home location register

Wirelineterminal

MSC

PSTN

BSS BSS

STP SS7HLRVLR

EIRAC

MSC = mobile switching centerPSTN = public switched telephone network STP = signal transfer point VLR = visitor location register

Cellular Network Physical Topology

Base stationbull Transmits to users on

forward channelsbull Receives from users

on reverse channels

Mobile Switching Center

bull Controls connection setup within cells amp to telephone network

I nternetInternet

Modified from Leon-Garcia amp Widjaja Communication Networks

Mobile Stations

12 4

Components

bull Mobile stations (MS)ndash TransmitReceive over the air interface

bull Signalingbull User information

ndash Voicendash Internetndash Video

ndash Will set up multiple ldquochannelsrdquo for communication

bull SignalingControlndash Set up and maintain callsndash Establish relationship between mobile unit and

nearest BSbull User voicedata channels traffic channels

12 5

Components

bull Base station (BS)ndash TransmitReceive over the air

interface to multiple mobile stationsndash Terminates radio signals ndash Packages information for transport to

a controller (MSC) for routingndash Sends information to Mobile Switching

Center

12 6

Components

bull Mobile Switching Center (MSC)ndash Connects to many BSsndash Performs call set upndash Provides routing functionsndash Typically associated with voice callsndash Sometines called Mobile Telecommunications Switching Office

(MST0)bull Home location register (HLR)

ndash Wireless service provider (WSP) maintains a databasebull Subscriber personal information eg phone number mobile

identification number electronic serial number (ESN) of phone bull Service Profilebull Current location of subscriber

ndash One HLR may serve several MSCsbull Visitor location register (VLR)

ndash Data base containing temporary information of subscribersndash For subscribers away from home service areandash VRL information retrieved from the HLR

12 7

Process

bull Registrationndash Turn on cell phonendash BS continually transmit

signals on control channelsndash Cell phone scans for

strongest signalndash Cell phone decodes control

signal to determinebull System Idbull Initial Tx power settingbull Radio channels to use for

further communicationsbull Cell phone registers with

network bull Note as the MS moves it

may need to cancel registration in old area and re-register in new area

12 8

Process

bull Mobile Call Initiationndash To make a call the

mobile keys the phone and hits send

ndash Phone transmitted over preselected control channel

ndash The BS relays information to the MSC

ndash MSC looking into the control message to get the and processes the call ie does the routing

12 9

Process

bull Call initiation to mobilendash Call routed to home MSCndash MSC checks HLR to

determine location of subscriber

ndash MSC has current visiting MSC stored in the HLR

ndash Home MSC communicates with the visiting MSC to rout the call

ndash The MSC sends a paging message to the paging message to BS

ndash The BS then send the paging message on to the subscriber on an assigned control (paging) channel

12 10

Process

bull Call acceptedndash MS sees the paging

signal and responds to the BS

ndash The BS send response to the MSC

ndash The MSC sets up the call to the BS

ndash The MSC also assigns a air interface channel for the BS to use for the call

ndash The MS communicates of the assigned channel

bull Here the call is between two mobiles

bull The communications is monitored for the ongoing call

12 11

Processbull Handoff (or handover)

ndash MS continually scans for control signals of BS

ndash Knowledge of the results of scans is used by MSC eg power of control signal drops below some threshold

ndash Upon that event the MSC will initiate a handoff procedure

ndash Handoff procedures can be implemented transparent to the users no interruption

ndash The handoff procedure tells the MS to use a specific channel to communicate with the new BS

12 12

Process

bull Handoffsndash Hard communications with old BS is terminated and

a new communications to a new BS is establishedndash Soft

bull Soft mobile station temporarily connected to more than one base station simultaneously

bull Softer mobile station temporarily connected to more than one sector of the same base station simultaneously

bull Soft-softer mobile station temporarily connected to more than one sector of the same base station and more than one base station simultaneously

bull Provides diversitybull Occurs at boundaries of sectorscells

12 13

Other Functions

bull Call blockingndash if all traffic channels busy

bull Call terminationndash when user hangs up

bull Call dropndash when BS cannot maintain required signal

strength

12 14

Other Functions Power control CDMA

bull Purposendash Removes near far effectndash Mitigates fadingndash Compensates changes in propagation conditionsndash In the system level

bull decrease interference from other usersbull increase capacity of the system

bull Uplinkndash Power control in uplink must make signal powers

from different users nearly equal in order to maximize the total capacity in the cell

bull Downlinkndash In downlink the power control must keep the signal

at minimal required level in order to decrease the interference to users in other cells

12 15

Other Functions Power control CDMA

bull Typesndash Open loop

bull set initial power for MSbull Each MS sets power based on individual

measurementsbull Coarse scale

ndash Closed loopbull BS knows receive power from each MSbull BS can tell each MS to set its power to achieve

system goalsbull Fast power control can mitigate fast fadingbull Three steps

ndash Transmissionndash Measurementndash Feedback

12 16

3G

bull 1G Analog Cellular Phones Needs a modem 96 kbps max

bull 2G Digital Cellular Phones No modem required 193 kbps max

bull 25G General Packet Radio Service (GPRS) 144kbps Data only

bull 3G Future high-speed data with Voice 64 kbps to 2 Mbpsndash W-CDMAUMTS (Universal Mobile

Telecommunications Systemndash CDMA2000

12 17

Organizations

ndash 3GPP 3rd Generation Partnership Project

ndash 3GPP is responsible for writing and maintaining the UMTS specifications

ndash hellip CDMA2000 hellipndash Internet Engineering Task Force (IETF)

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 18

3G- Advantages

3G phones promise - bull Improved digital voice communications bull Larger Bandwidth ndash Higher Data ratebull Greater subscriber capacity bull Fast packet-based data services like e-mail

short message service (SMS) and Internet access at broadband speeds

bull Most carriers also expect consumers to want - ndash location services ndash interactive gaming ndash streaming video ndash home monitoring and control ndash and who knows what else while being fully mobile

anywhere in the world

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 19

3G Capabilitiesbull Voice quality comparable to the public

switched telephone networkbull 144 Kbps- user in high-speed motor vehiclesbull 384 Kbps- pedestrians standing or moving

slowly over small areasbull Up to 2 Mbps- fixed applications like office usebull Symmetricalasymmetrical data transmission

ratesbull Support for both packet switched and circuit

switched data services like Internet Protocol (IP) traffic and real time video

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 20

Technologies

bull 3G is superior to the other digital standards like-ndash GSM (Global System for Mobile) communications standard

used worldwide ndash And IS-136 TDMA standard used primarily in North America ndash IS-95 CDMA systems

bull 3G Technologies-

ndash WCDMA or UMTS-FDD (Universal Mobile Telecommunications System - Frequency Division Duplex)---Direct Spread

ndash CDMA2000 - 1x-EvDOEvDV---Multi carrier

ndash UMTS ndash TDD (Time Division Duplex) or TD-SCDMA (Time Division - Synchronous Code Division Multiple Access) ---Time Code

ndash CDMA2000 and WCDMA or UMTS-FDD have similar architectures

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 21

Evolution Paths

25G2G 3G

cdmaOneIS-95A

TDMA

cdmaOneIS-95B Cdma2000 1X

Cdma20001xEV-DV

Cdma20001xEV-DO

GSMGPRS

EDGE WCDMA

GSM Map Core Network

IS-41 Core Network

25G2G 3G

cdmaOneIS-95A

TDMA

cdmaOneIS-95B Cdma2000 1X

Cdma20001xEV-DV

Cdma20001xEV-DO

GSMGPRS

EDGE WCDMA

GSM Map Core Network

IS-41 Core Network

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 22

WCDMA

bull Spectrumndash 1920 MHz ndash 1980 MHz (uplink)ndash 2110 MHz ndash 2170 MHz (downlink)orndash 1850 MHz ndash 1910 MHz (uplink)ndash 1930 MHz ndash 1990 MHz (downlink)ndash Channel Spacing 5 Mhz

bull WCDMA is connected to the FDD Phy and the associated protocols Focus here

bull UTRAN-Universal Terrestrial Radio Access Network- is associated with the WCDMA radio Access Network

bull UMTS refers to the whole network

12 23

UMTS-FDD WCDMA

bull Wideband Direct Sequence Code Division Multiple Access

bull Does not assign a specific frequency to each user Instead every channel uses the full available spectrum

bull Individual conversations are encoded with a pseudo-random digital sequence

bull See httpwwwumtsworldcomtechnologyoverviewhtm

12 24

WCDMA Parameters

Channel BW 5 MHz

Forward RF Channel Structure Direct Spread

Chip Rate 384 Mcps

Frame Length 10 ms (38400 chips)

No of slotsframe 15

No of chipsslot 2560chips (Max 2560 bits)

Power Control Open and fast close loop (16 KHz)

Uplink Spreading Factor 4 to 256

Downlink Spreading Factor 4 to 512

12 25

Spreading Operation

bull Spreading means increasing the signal bandwidthbull Strictly speaking spreading includes two

operationsndash Channelisation (increases signal bandwidth) using

orthogonal codesndash Scrambling (does not affect the signal bandwidth) using

pseudo noise codes

12 26

Codes

Channellization Code Scrambling Code

Usage UL Separation of physical dataand control channels from same UEDL Separation of different userswithin one cell

UL Separation of terminalsDL Separation ofcellssectors

Length UL4-256 chipsDL4-512 chips

38400 chips

No of codes No of codes under one scrambling code= SF

UL Several millionDL 512

Code Family Orthogonal Variable Spreading Factor

Long 10ms code Gold codeShort code Extended S(2) code Family

Increase BW YES NO

12 27

UMTS Architecture

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

Cell site

Access Network

Core Network

User Equipment

12 28

UMTS Architecture

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 29

UMTS Architecture

bull User equipment-UEndash UMTS Subscriber Identity Module ndashUSIMndash Mobile Equipment- cell phone

bull UMTS Terrestrial Radio Access Networkndash Radio Network Subsystem

bull Node B- BSndash Transceiverndash Rate adaptationndash Radio resource managementndash Power control

12 30

UMTS Architecture

bull Radio Network Controller ndash RNCndash Radio access controlndash Connection controlndash Load congestion and admission controlndash Code allocation

ndash Core Networkbull MSCbull VLRbull HLRbull Gateway MSC ndash GMSC

ndash Supports circuit switched connectionsbull Serving GRPS Support Node ndash SGPRS

ndash Logical interface to UTRAN for packet transportraquo Session managementraquo Logical link management

bull Gateway GPRS Support Node ndash GGSNndash Supports packet switched transportndash This is an IP router

12 31

UMTS Protocol Architecture - User Plane

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

FP= Framing Protocol GTP-U= GPRS Tunneling Protocol-UserPDCP =Packet Data convergence Protocol

12 32

UMTS Protocol Stack

bull Radio Resource Control-RRC

bull Broadcastmulitcast control- BMC

bull Packet Data convergence Protocol- PDCPndash Header

compression

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

12 33

Packet SAR

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

12 34

Physical Layerbull The physical layer offers information transfer services to

the MAC layer These services are denoted as Transport channels (TrChrsquos) There are also Physical channels

bull Physical layer comprises following functionsndash 1048713 Various handover functionsndash 1048713 Error detection and report to higher layersndash 1048713 Multiplexing of transport channelsndash 1048713 Mapping of transport channels to physical channelsndash 1048713 Fast Close loop Power controlndash 1048713 Frequency and Time Synchronizationndash 1048713 Other responsibilities associated with transmitting and

receiving signals over the wireless mediandash Measurements

bull SIRbull Tx power Frame error rate etc

bull Physical channel is assigned a specific code

12 35

Transport amp Physical Channels

Transport Channel Physical Channel(ULDL) Dedicated Channel DCH Dedicated Physical Data Channel DPDCH

Dedicated Physical Control Channel DPCCH

(UL) Random Access Channel RACH Physical random access channel PRACH

(UL) Common packet channel CPCH Physical common packet channel PCPCH

(DL) Broadcast channel BCH Primary common control physical channel P-CCPCH

(DL) Forward access channel FACH(DL) Paging channel PCH

Secondary common control physical channel S-CCPCH

(DL) Downlink shared channel DSCH Physical downlink shared channel PDSCH

Signaling physical channels

Synchronization channel SCHCommon pilot channel CPICHAcquisition indication channel AICHPaging indication channel PICHCPCH Status indication channel CSICHCollision detectionChannel assignment indicator channel CDCA-ICH

12 36

UMTS FDD frame structure

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 37

MAC Layer

bull The MAC layer offers Data transfer to RLC and higher layers

bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically

bit rate within a predefined set per information unit delivered to the physical layer

ndash Service multiplexing on RACH FACH and dedicated channels

ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling

ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements

12 38

Physical Layer

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 39

RRC Layerbull The RRC layer offers the core network the following

servicesndash General control service which is used as an information

broadcast servicendash Notification service which is used for paging and

notification of a selected UEsndash Dedicated control service which is used for

establishmentrelease of a connection and transfer of messages using the connection

bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover

admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection

12 40

RLC Layer

bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is

appended to the information unit received from the higher layer

ndash Assured and un assured data transferbull The RLC layer comprises the following functions

ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the

WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the

control plane)ndash Duplicate detectionndash Flow controlndash Ciphering

12 41

RLC Layer-Modesbull Transparent-TM

ndash No header attachedndash SARndash SDU discard

bull Delete SDU if not sent before timer expiresndash Used for

bull Voicebull Some signaling

bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability

bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat

12 42

RLC Layer

From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the

UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

12 43

UE-Call states

bull Designed to ndash Take advantage of bursty nature of

datandash Save batter powerndash Maintains logical session and tracks

mobility but when appropriatendash releases dedicated resources to

increase overall capacityndash asleeps the UE

12 44

UE-Call states

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 45

UE-Call states

bull Idle modendash No active sessionndash UE monitors

Paging CHndash Sleeps between

paging cycles

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 46

UE-Call states

bull CELL_DCH state (Dedicated)ndash A dedicated physical

channel is allocated to the UE in uplink and downlink

ndash The UE is known on cell level according to its current active set

ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE

ndash Call typesbull Circuit Switched always in

this statebull Packet Switched in this

state if transferring large volume of data

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 47

UE-Call states

bull CELL_FACH state(Forward Access Ch)

ndash No dedicated physical channel is allocated to the UE

ndash The UE continuously monitors a FACH in the downlink

ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel

ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update

ndash Radio not put to sleepndash For packet switched sessions

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 48

UE-Call states

bull CELL_PCH state (Paging Ch)ndash No dedicated physical

channel is allocated to the UE

ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash Sleep between pagesndash A logical session is still upndash The position of the UE is

known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 49

UE-Call states

bull URA_PCH State ndash No dedicated channel is

allocated to the UEndash The UE selects a PCH with

the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state

ndash Similar to CELL_PCH state only the at the URA level

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 50

Power Control-PC

bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to

ensure that there is enough power for mobiles at the cell edge

bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control

commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command

ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break

12 51

Power Control

bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss

by means of a downlink beacon signalndash Provide a coarse initial power setting of

the mobile at the beginning of a connection

ndash Apply only prior to initiating the transmission on RACH or CPCH

12 52

Packet Access in WCDMA

bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection

bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared

bull RNC can decide when and how to send packets based on type of packet traffic

ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech

ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video

ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing

ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail

bull RNC can assign a packet to a specific channel

Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 53

Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the

downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft

handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts

bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts

bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink

orthogonal code is reserved according to maximum bit rate

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 54

Packet Access in WCDMA

bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner

bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer

bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate

bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and

bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 55

Packet Access in WCDMA

bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased

bull Advantagesndash resources are in full usage due to longer transmission

timendash small variation in interference levelndash longer uplink range due to lower bit rate

bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 56

Packet Access in WCDMA

bull Time division is normally used with shared channels and code division is normally used with dedicated channels

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 57

Packet Access in WCDMA

bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users

could be based on required transmission powerbull Users close to the BS requires less

transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate

bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput

bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 58

HSDPA amp Enhance Uplink

bull HSDPA = High Speed Downlink Packet Access

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 59

HSDPA amp Enhance Uplink

bull Remember it is better (more efficient) to have a large number of users sharing a single server

bull This lead to a desire to have fast allocation of shared resources

bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code

bull Uplink resourcesndash Interference at the BS

bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)

bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)

12 60

HSDPA amp Enhance Uplink

bull UTRAN Architecture with HSDPA and enhanced uplink

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 61

HSDPA amp Enhance Uplink

bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK

modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and

coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function

moved to Node-B (WCDMA packet scheduling was done in the RNC)

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 62

HSDPA amp Enhance Uplink

bull Gain in Performance

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 63

HSDPA

bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to

individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes

bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)

12 64

HSDPA

bull New frame structurendash Five subframesW-CDMA

framendash User data can be

assigned on a subframe basis

ndash System can adjust in 2ms

ndash Each subframe is a transmission time interval (TTI) = 2ms

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 65

HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared

resource is also in the time domain

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 66

HSDPA

bull Another view

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

Spreading Code

12 67

HSDPAbull Link Adaptation

ndash Remember the fast power control is commonly used to

bull Maintain constant EnergyNoise ratiobull Reduce effect of fading

ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant

EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 68

HSDPA

ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)

ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum

bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user

bull 1 ndash 2 Mbs closer to achievable under real conditions

12 69

HSDPA

bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE

bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms

bull CQI (0-30) each mapping into a modulation SF etc

bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression

bull

12 70

HSDPA

bull Schedulingndash The scheduler decides which user

should get access to each TTI ndash CQI provides input into a Scheduler

bull Proportional Fair (PF) Scheduler can be uses

bull Implementation Specific

12 71

HSDPA

bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number

of spreading codes limits rate not power so likely receive first transmission

ndash At greater distances move from BS see more errors IR will require additional transmission but not many

ndash HARQ only retransmit upon an ACK or NACK

12 72

HSDPA

From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007

12 73

HSDPA

bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2

ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent

Scheduling

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 3

AC = authentication center BSS = base station subsystem EIR = equipment identity register HLR = home location register

Wirelineterminal

MSC

PSTN

BSS BSS

STP SS7HLRVLR

EIRAC

MSC = mobile switching centerPSTN = public switched telephone network STP = signal transfer point VLR = visitor location register

Cellular Network Physical Topology

Base stationbull Transmits to users on

forward channelsbull Receives from users

on reverse channels

Mobile Switching Center

bull Controls connection setup within cells amp to telephone network

I nternetInternet

Modified from Leon-Garcia amp Widjaja Communication Networks

Mobile Stations

12 4

Components

bull Mobile stations (MS)ndash TransmitReceive over the air interface

bull Signalingbull User information

ndash Voicendash Internetndash Video

ndash Will set up multiple ldquochannelsrdquo for communication

bull SignalingControlndash Set up and maintain callsndash Establish relationship between mobile unit and

nearest BSbull User voicedata channels traffic channels

12 5

Components

bull Base station (BS)ndash TransmitReceive over the air

interface to multiple mobile stationsndash Terminates radio signals ndash Packages information for transport to

a controller (MSC) for routingndash Sends information to Mobile Switching

Center

12 6

Components

bull Mobile Switching Center (MSC)ndash Connects to many BSsndash Performs call set upndash Provides routing functionsndash Typically associated with voice callsndash Sometines called Mobile Telecommunications Switching Office

(MST0)bull Home location register (HLR)

ndash Wireless service provider (WSP) maintains a databasebull Subscriber personal information eg phone number mobile

identification number electronic serial number (ESN) of phone bull Service Profilebull Current location of subscriber

ndash One HLR may serve several MSCsbull Visitor location register (VLR)

ndash Data base containing temporary information of subscribersndash For subscribers away from home service areandash VRL information retrieved from the HLR

12 7

Process

bull Registrationndash Turn on cell phonendash BS continually transmit

signals on control channelsndash Cell phone scans for

strongest signalndash Cell phone decodes control

signal to determinebull System Idbull Initial Tx power settingbull Radio channels to use for

further communicationsbull Cell phone registers with

network bull Note as the MS moves it

may need to cancel registration in old area and re-register in new area

12 8

Process

bull Mobile Call Initiationndash To make a call the

mobile keys the phone and hits send

ndash Phone transmitted over preselected control channel

ndash The BS relays information to the MSC

ndash MSC looking into the control message to get the and processes the call ie does the routing

12 9

Process

bull Call initiation to mobilendash Call routed to home MSCndash MSC checks HLR to

determine location of subscriber

ndash MSC has current visiting MSC stored in the HLR

ndash Home MSC communicates with the visiting MSC to rout the call

ndash The MSC sends a paging message to the paging message to BS

ndash The BS then send the paging message on to the subscriber on an assigned control (paging) channel

12 10

Process

bull Call acceptedndash MS sees the paging

signal and responds to the BS

ndash The BS send response to the MSC

ndash The MSC sets up the call to the BS

ndash The MSC also assigns a air interface channel for the BS to use for the call

ndash The MS communicates of the assigned channel

bull Here the call is between two mobiles

bull The communications is monitored for the ongoing call

12 11

Processbull Handoff (or handover)

ndash MS continually scans for control signals of BS

ndash Knowledge of the results of scans is used by MSC eg power of control signal drops below some threshold

ndash Upon that event the MSC will initiate a handoff procedure

ndash Handoff procedures can be implemented transparent to the users no interruption

ndash The handoff procedure tells the MS to use a specific channel to communicate with the new BS

12 12

Process

bull Handoffsndash Hard communications with old BS is terminated and

a new communications to a new BS is establishedndash Soft

bull Soft mobile station temporarily connected to more than one base station simultaneously

bull Softer mobile station temporarily connected to more than one sector of the same base station simultaneously

bull Soft-softer mobile station temporarily connected to more than one sector of the same base station and more than one base station simultaneously

bull Provides diversitybull Occurs at boundaries of sectorscells

12 13

Other Functions

bull Call blockingndash if all traffic channels busy

bull Call terminationndash when user hangs up

bull Call dropndash when BS cannot maintain required signal

strength

12 14

Other Functions Power control CDMA

bull Purposendash Removes near far effectndash Mitigates fadingndash Compensates changes in propagation conditionsndash In the system level

bull decrease interference from other usersbull increase capacity of the system

bull Uplinkndash Power control in uplink must make signal powers

from different users nearly equal in order to maximize the total capacity in the cell

bull Downlinkndash In downlink the power control must keep the signal

at minimal required level in order to decrease the interference to users in other cells

12 15

Other Functions Power control CDMA

bull Typesndash Open loop

bull set initial power for MSbull Each MS sets power based on individual

measurementsbull Coarse scale

ndash Closed loopbull BS knows receive power from each MSbull BS can tell each MS to set its power to achieve

system goalsbull Fast power control can mitigate fast fadingbull Three steps

ndash Transmissionndash Measurementndash Feedback

12 16

3G

bull 1G Analog Cellular Phones Needs a modem 96 kbps max

bull 2G Digital Cellular Phones No modem required 193 kbps max

bull 25G General Packet Radio Service (GPRS) 144kbps Data only

bull 3G Future high-speed data with Voice 64 kbps to 2 Mbpsndash W-CDMAUMTS (Universal Mobile

Telecommunications Systemndash CDMA2000

12 17

Organizations

ndash 3GPP 3rd Generation Partnership Project

ndash 3GPP is responsible for writing and maintaining the UMTS specifications

ndash hellip CDMA2000 hellipndash Internet Engineering Task Force (IETF)

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 18

3G- Advantages

3G phones promise - bull Improved digital voice communications bull Larger Bandwidth ndash Higher Data ratebull Greater subscriber capacity bull Fast packet-based data services like e-mail

short message service (SMS) and Internet access at broadband speeds

bull Most carriers also expect consumers to want - ndash location services ndash interactive gaming ndash streaming video ndash home monitoring and control ndash and who knows what else while being fully mobile

anywhere in the world

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 19

3G Capabilitiesbull Voice quality comparable to the public

switched telephone networkbull 144 Kbps- user in high-speed motor vehiclesbull 384 Kbps- pedestrians standing or moving

slowly over small areasbull Up to 2 Mbps- fixed applications like office usebull Symmetricalasymmetrical data transmission

ratesbull Support for both packet switched and circuit

switched data services like Internet Protocol (IP) traffic and real time video

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 20

Technologies

bull 3G is superior to the other digital standards like-ndash GSM (Global System for Mobile) communications standard

used worldwide ndash And IS-136 TDMA standard used primarily in North America ndash IS-95 CDMA systems

bull 3G Technologies-

ndash WCDMA or UMTS-FDD (Universal Mobile Telecommunications System - Frequency Division Duplex)---Direct Spread

ndash CDMA2000 - 1x-EvDOEvDV---Multi carrier

ndash UMTS ndash TDD (Time Division Duplex) or TD-SCDMA (Time Division - Synchronous Code Division Multiple Access) ---Time Code

ndash CDMA2000 and WCDMA or UMTS-FDD have similar architectures

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 21

Evolution Paths

25G2G 3G

cdmaOneIS-95A

TDMA

cdmaOneIS-95B Cdma2000 1X

Cdma20001xEV-DV

Cdma20001xEV-DO

GSMGPRS

EDGE WCDMA

GSM Map Core Network

IS-41 Core Network

25G2G 3G

cdmaOneIS-95A

TDMA

cdmaOneIS-95B Cdma2000 1X

Cdma20001xEV-DV

Cdma20001xEV-DO

GSMGPRS

EDGE WCDMA

GSM Map Core Network

IS-41 Core Network

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 22

WCDMA

bull Spectrumndash 1920 MHz ndash 1980 MHz (uplink)ndash 2110 MHz ndash 2170 MHz (downlink)orndash 1850 MHz ndash 1910 MHz (uplink)ndash 1930 MHz ndash 1990 MHz (downlink)ndash Channel Spacing 5 Mhz

bull WCDMA is connected to the FDD Phy and the associated protocols Focus here

bull UTRAN-Universal Terrestrial Radio Access Network- is associated with the WCDMA radio Access Network

bull UMTS refers to the whole network

12 23

UMTS-FDD WCDMA

bull Wideband Direct Sequence Code Division Multiple Access

bull Does not assign a specific frequency to each user Instead every channel uses the full available spectrum

bull Individual conversations are encoded with a pseudo-random digital sequence

bull See httpwwwumtsworldcomtechnologyoverviewhtm

12 24

WCDMA Parameters

Channel BW 5 MHz

Forward RF Channel Structure Direct Spread

Chip Rate 384 Mcps

Frame Length 10 ms (38400 chips)

No of slotsframe 15

No of chipsslot 2560chips (Max 2560 bits)

Power Control Open and fast close loop (16 KHz)

Uplink Spreading Factor 4 to 256

Downlink Spreading Factor 4 to 512

12 25

Spreading Operation

bull Spreading means increasing the signal bandwidthbull Strictly speaking spreading includes two

operationsndash Channelisation (increases signal bandwidth) using

orthogonal codesndash Scrambling (does not affect the signal bandwidth) using

pseudo noise codes

12 26

Codes

Channellization Code Scrambling Code

Usage UL Separation of physical dataand control channels from same UEDL Separation of different userswithin one cell

UL Separation of terminalsDL Separation ofcellssectors

Length UL4-256 chipsDL4-512 chips

38400 chips

No of codes No of codes under one scrambling code= SF

UL Several millionDL 512

Code Family Orthogonal Variable Spreading Factor

Long 10ms code Gold codeShort code Extended S(2) code Family

Increase BW YES NO

12 27

UMTS Architecture

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

Cell site

Access Network

Core Network

User Equipment

12 28

UMTS Architecture

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 29

UMTS Architecture

bull User equipment-UEndash UMTS Subscriber Identity Module ndashUSIMndash Mobile Equipment- cell phone

bull UMTS Terrestrial Radio Access Networkndash Radio Network Subsystem

bull Node B- BSndash Transceiverndash Rate adaptationndash Radio resource managementndash Power control

12 30

UMTS Architecture

bull Radio Network Controller ndash RNCndash Radio access controlndash Connection controlndash Load congestion and admission controlndash Code allocation

ndash Core Networkbull MSCbull VLRbull HLRbull Gateway MSC ndash GMSC

ndash Supports circuit switched connectionsbull Serving GRPS Support Node ndash SGPRS

ndash Logical interface to UTRAN for packet transportraquo Session managementraquo Logical link management

bull Gateway GPRS Support Node ndash GGSNndash Supports packet switched transportndash This is an IP router

12 31

UMTS Protocol Architecture - User Plane

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

FP= Framing Protocol GTP-U= GPRS Tunneling Protocol-UserPDCP =Packet Data convergence Protocol

12 32

UMTS Protocol Stack

bull Radio Resource Control-RRC

bull Broadcastmulitcast control- BMC

bull Packet Data convergence Protocol- PDCPndash Header

compression

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

12 33

Packet SAR

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

12 34

Physical Layerbull The physical layer offers information transfer services to

the MAC layer These services are denoted as Transport channels (TrChrsquos) There are also Physical channels

bull Physical layer comprises following functionsndash 1048713 Various handover functionsndash 1048713 Error detection and report to higher layersndash 1048713 Multiplexing of transport channelsndash 1048713 Mapping of transport channels to physical channelsndash 1048713 Fast Close loop Power controlndash 1048713 Frequency and Time Synchronizationndash 1048713 Other responsibilities associated with transmitting and

receiving signals over the wireless mediandash Measurements

bull SIRbull Tx power Frame error rate etc

bull Physical channel is assigned a specific code

12 35

Transport amp Physical Channels

Transport Channel Physical Channel(ULDL) Dedicated Channel DCH Dedicated Physical Data Channel DPDCH

Dedicated Physical Control Channel DPCCH

(UL) Random Access Channel RACH Physical random access channel PRACH

(UL) Common packet channel CPCH Physical common packet channel PCPCH

(DL) Broadcast channel BCH Primary common control physical channel P-CCPCH

(DL) Forward access channel FACH(DL) Paging channel PCH

Secondary common control physical channel S-CCPCH

(DL) Downlink shared channel DSCH Physical downlink shared channel PDSCH

Signaling physical channels

Synchronization channel SCHCommon pilot channel CPICHAcquisition indication channel AICHPaging indication channel PICHCPCH Status indication channel CSICHCollision detectionChannel assignment indicator channel CDCA-ICH

12 36

UMTS FDD frame structure

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 37

MAC Layer

bull The MAC layer offers Data transfer to RLC and higher layers

bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically

bit rate within a predefined set per information unit delivered to the physical layer

ndash Service multiplexing on RACH FACH and dedicated channels

ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling

ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements

12 38

Physical Layer

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 39

RRC Layerbull The RRC layer offers the core network the following

servicesndash General control service which is used as an information

broadcast servicendash Notification service which is used for paging and

notification of a selected UEsndash Dedicated control service which is used for

establishmentrelease of a connection and transfer of messages using the connection

bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover

admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection

12 40

RLC Layer

bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is

appended to the information unit received from the higher layer

ndash Assured and un assured data transferbull The RLC layer comprises the following functions

ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the

WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the

control plane)ndash Duplicate detectionndash Flow controlndash Ciphering

12 41

RLC Layer-Modesbull Transparent-TM

ndash No header attachedndash SARndash SDU discard

bull Delete SDU if not sent before timer expiresndash Used for

bull Voicebull Some signaling

bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability

bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat

12 42

RLC Layer

From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the

UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

12 43

UE-Call states

bull Designed to ndash Take advantage of bursty nature of

datandash Save batter powerndash Maintains logical session and tracks

mobility but when appropriatendash releases dedicated resources to

increase overall capacityndash asleeps the UE

12 44

UE-Call states

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 45

UE-Call states

bull Idle modendash No active sessionndash UE monitors

Paging CHndash Sleeps between

paging cycles

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 46

UE-Call states

bull CELL_DCH state (Dedicated)ndash A dedicated physical

channel is allocated to the UE in uplink and downlink

ndash The UE is known on cell level according to its current active set

ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE

ndash Call typesbull Circuit Switched always in

this statebull Packet Switched in this

state if transferring large volume of data

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 47

UE-Call states

bull CELL_FACH state(Forward Access Ch)

ndash No dedicated physical channel is allocated to the UE

ndash The UE continuously monitors a FACH in the downlink

ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel

ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update

ndash Radio not put to sleepndash For packet switched sessions

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 48

UE-Call states

bull CELL_PCH state (Paging Ch)ndash No dedicated physical

channel is allocated to the UE

ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash Sleep between pagesndash A logical session is still upndash The position of the UE is

known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 49

UE-Call states

bull URA_PCH State ndash No dedicated channel is

allocated to the UEndash The UE selects a PCH with

the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state

ndash Similar to CELL_PCH state only the at the URA level

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 50

Power Control-PC

bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to

ensure that there is enough power for mobiles at the cell edge

bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control

commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command

ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break

12 51

Power Control

bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss

by means of a downlink beacon signalndash Provide a coarse initial power setting of

the mobile at the beginning of a connection

ndash Apply only prior to initiating the transmission on RACH or CPCH

12 52

Packet Access in WCDMA

bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection

bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared

bull RNC can decide when and how to send packets based on type of packet traffic

ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech

ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video

ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing

ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail

bull RNC can assign a packet to a specific channel

Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 53

Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the

downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft

handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts

bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts

bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink

orthogonal code is reserved according to maximum bit rate

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 54

Packet Access in WCDMA

bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner

bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer

bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate

bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and

bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 55

Packet Access in WCDMA

bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased

bull Advantagesndash resources are in full usage due to longer transmission

timendash small variation in interference levelndash longer uplink range due to lower bit rate

bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 56

Packet Access in WCDMA

bull Time division is normally used with shared channels and code division is normally used with dedicated channels

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 57

Packet Access in WCDMA

bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users

could be based on required transmission powerbull Users close to the BS requires less

transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate

bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput

bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 58

HSDPA amp Enhance Uplink

bull HSDPA = High Speed Downlink Packet Access

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 59

HSDPA amp Enhance Uplink

bull Remember it is better (more efficient) to have a large number of users sharing a single server

bull This lead to a desire to have fast allocation of shared resources

bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code

bull Uplink resourcesndash Interference at the BS

bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)

bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)

12 60

HSDPA amp Enhance Uplink

bull UTRAN Architecture with HSDPA and enhanced uplink

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 61

HSDPA amp Enhance Uplink

bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK

modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and

coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function

moved to Node-B (WCDMA packet scheduling was done in the RNC)

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 62

HSDPA amp Enhance Uplink

bull Gain in Performance

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 63

HSDPA

bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to

individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes

bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)

12 64

HSDPA

bull New frame structurendash Five subframesW-CDMA

framendash User data can be

assigned on a subframe basis

ndash System can adjust in 2ms

ndash Each subframe is a transmission time interval (TTI) = 2ms

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 65

HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared

resource is also in the time domain

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 66

HSDPA

bull Another view

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

Spreading Code

12 67

HSDPAbull Link Adaptation

ndash Remember the fast power control is commonly used to

bull Maintain constant EnergyNoise ratiobull Reduce effect of fading

ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant

EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 68

HSDPA

ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)

ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum

bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user

bull 1 ndash 2 Mbs closer to achievable under real conditions

12 69

HSDPA

bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE

bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms

bull CQI (0-30) each mapping into a modulation SF etc

bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression

bull

12 70

HSDPA

bull Schedulingndash The scheduler decides which user

should get access to each TTI ndash CQI provides input into a Scheduler

bull Proportional Fair (PF) Scheduler can be uses

bull Implementation Specific

12 71

HSDPA

bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number

of spreading codes limits rate not power so likely receive first transmission

ndash At greater distances move from BS see more errors IR will require additional transmission but not many

ndash HARQ only retransmit upon an ACK or NACK

12 72

HSDPA

From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007

12 73

HSDPA

bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2

ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent

Scheduling

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 4

Components

bull Mobile stations (MS)ndash TransmitReceive over the air interface

bull Signalingbull User information

ndash Voicendash Internetndash Video

ndash Will set up multiple ldquochannelsrdquo for communication

bull SignalingControlndash Set up and maintain callsndash Establish relationship between mobile unit and

nearest BSbull User voicedata channels traffic channels

12 5

Components

bull Base station (BS)ndash TransmitReceive over the air

interface to multiple mobile stationsndash Terminates radio signals ndash Packages information for transport to

a controller (MSC) for routingndash Sends information to Mobile Switching

Center

12 6

Components

bull Mobile Switching Center (MSC)ndash Connects to many BSsndash Performs call set upndash Provides routing functionsndash Typically associated with voice callsndash Sometines called Mobile Telecommunications Switching Office

(MST0)bull Home location register (HLR)

ndash Wireless service provider (WSP) maintains a databasebull Subscriber personal information eg phone number mobile

identification number electronic serial number (ESN) of phone bull Service Profilebull Current location of subscriber

ndash One HLR may serve several MSCsbull Visitor location register (VLR)

ndash Data base containing temporary information of subscribersndash For subscribers away from home service areandash VRL information retrieved from the HLR

12 7

Process

bull Registrationndash Turn on cell phonendash BS continually transmit

signals on control channelsndash Cell phone scans for

strongest signalndash Cell phone decodes control

signal to determinebull System Idbull Initial Tx power settingbull Radio channels to use for

further communicationsbull Cell phone registers with

network bull Note as the MS moves it

may need to cancel registration in old area and re-register in new area

12 8

Process

bull Mobile Call Initiationndash To make a call the

mobile keys the phone and hits send

ndash Phone transmitted over preselected control channel

ndash The BS relays information to the MSC

ndash MSC looking into the control message to get the and processes the call ie does the routing

12 9

Process

bull Call initiation to mobilendash Call routed to home MSCndash MSC checks HLR to

determine location of subscriber

ndash MSC has current visiting MSC stored in the HLR

ndash Home MSC communicates with the visiting MSC to rout the call

ndash The MSC sends a paging message to the paging message to BS

ndash The BS then send the paging message on to the subscriber on an assigned control (paging) channel

12 10

Process

bull Call acceptedndash MS sees the paging

signal and responds to the BS

ndash The BS send response to the MSC

ndash The MSC sets up the call to the BS

ndash The MSC also assigns a air interface channel for the BS to use for the call

ndash The MS communicates of the assigned channel

bull Here the call is between two mobiles

bull The communications is monitored for the ongoing call

12 11

Processbull Handoff (or handover)

ndash MS continually scans for control signals of BS

ndash Knowledge of the results of scans is used by MSC eg power of control signal drops below some threshold

ndash Upon that event the MSC will initiate a handoff procedure

ndash Handoff procedures can be implemented transparent to the users no interruption

ndash The handoff procedure tells the MS to use a specific channel to communicate with the new BS

12 12

Process

bull Handoffsndash Hard communications with old BS is terminated and

a new communications to a new BS is establishedndash Soft

bull Soft mobile station temporarily connected to more than one base station simultaneously

bull Softer mobile station temporarily connected to more than one sector of the same base station simultaneously

bull Soft-softer mobile station temporarily connected to more than one sector of the same base station and more than one base station simultaneously

bull Provides diversitybull Occurs at boundaries of sectorscells

12 13

Other Functions

bull Call blockingndash if all traffic channels busy

bull Call terminationndash when user hangs up

bull Call dropndash when BS cannot maintain required signal

strength

12 14

Other Functions Power control CDMA

bull Purposendash Removes near far effectndash Mitigates fadingndash Compensates changes in propagation conditionsndash In the system level

bull decrease interference from other usersbull increase capacity of the system

bull Uplinkndash Power control in uplink must make signal powers

from different users nearly equal in order to maximize the total capacity in the cell

bull Downlinkndash In downlink the power control must keep the signal

at minimal required level in order to decrease the interference to users in other cells

12 15

Other Functions Power control CDMA

bull Typesndash Open loop

bull set initial power for MSbull Each MS sets power based on individual

measurementsbull Coarse scale

ndash Closed loopbull BS knows receive power from each MSbull BS can tell each MS to set its power to achieve

system goalsbull Fast power control can mitigate fast fadingbull Three steps

ndash Transmissionndash Measurementndash Feedback

12 16

3G

bull 1G Analog Cellular Phones Needs a modem 96 kbps max

bull 2G Digital Cellular Phones No modem required 193 kbps max

bull 25G General Packet Radio Service (GPRS) 144kbps Data only

bull 3G Future high-speed data with Voice 64 kbps to 2 Mbpsndash W-CDMAUMTS (Universal Mobile

Telecommunications Systemndash CDMA2000

12 17

Organizations

ndash 3GPP 3rd Generation Partnership Project

ndash 3GPP is responsible for writing and maintaining the UMTS specifications

ndash hellip CDMA2000 hellipndash Internet Engineering Task Force (IETF)

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 18

3G- Advantages

3G phones promise - bull Improved digital voice communications bull Larger Bandwidth ndash Higher Data ratebull Greater subscriber capacity bull Fast packet-based data services like e-mail

short message service (SMS) and Internet access at broadband speeds

bull Most carriers also expect consumers to want - ndash location services ndash interactive gaming ndash streaming video ndash home monitoring and control ndash and who knows what else while being fully mobile

anywhere in the world

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 19

3G Capabilitiesbull Voice quality comparable to the public

switched telephone networkbull 144 Kbps- user in high-speed motor vehiclesbull 384 Kbps- pedestrians standing or moving

slowly over small areasbull Up to 2 Mbps- fixed applications like office usebull Symmetricalasymmetrical data transmission

ratesbull Support for both packet switched and circuit

switched data services like Internet Protocol (IP) traffic and real time video

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 20

Technologies

bull 3G is superior to the other digital standards like-ndash GSM (Global System for Mobile) communications standard

used worldwide ndash And IS-136 TDMA standard used primarily in North America ndash IS-95 CDMA systems

bull 3G Technologies-

ndash WCDMA or UMTS-FDD (Universal Mobile Telecommunications System - Frequency Division Duplex)---Direct Spread

ndash CDMA2000 - 1x-EvDOEvDV---Multi carrier

ndash UMTS ndash TDD (Time Division Duplex) or TD-SCDMA (Time Division - Synchronous Code Division Multiple Access) ---Time Code

ndash CDMA2000 and WCDMA or UMTS-FDD have similar architectures

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 21

Evolution Paths

25G2G 3G

cdmaOneIS-95A

TDMA

cdmaOneIS-95B Cdma2000 1X

Cdma20001xEV-DV

Cdma20001xEV-DO

GSMGPRS

EDGE WCDMA

GSM Map Core Network

IS-41 Core Network

25G2G 3G

cdmaOneIS-95A

TDMA

cdmaOneIS-95B Cdma2000 1X

Cdma20001xEV-DV

Cdma20001xEV-DO

GSMGPRS

EDGE WCDMA

GSM Map Core Network

IS-41 Core Network

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 22

WCDMA

bull Spectrumndash 1920 MHz ndash 1980 MHz (uplink)ndash 2110 MHz ndash 2170 MHz (downlink)orndash 1850 MHz ndash 1910 MHz (uplink)ndash 1930 MHz ndash 1990 MHz (downlink)ndash Channel Spacing 5 Mhz

bull WCDMA is connected to the FDD Phy and the associated protocols Focus here

bull UTRAN-Universal Terrestrial Radio Access Network- is associated with the WCDMA radio Access Network

bull UMTS refers to the whole network

12 23

UMTS-FDD WCDMA

bull Wideband Direct Sequence Code Division Multiple Access

bull Does not assign a specific frequency to each user Instead every channel uses the full available spectrum

bull Individual conversations are encoded with a pseudo-random digital sequence

bull See httpwwwumtsworldcomtechnologyoverviewhtm

12 24

WCDMA Parameters

Channel BW 5 MHz

Forward RF Channel Structure Direct Spread

Chip Rate 384 Mcps

Frame Length 10 ms (38400 chips)

No of slotsframe 15

No of chipsslot 2560chips (Max 2560 bits)

Power Control Open and fast close loop (16 KHz)

Uplink Spreading Factor 4 to 256

Downlink Spreading Factor 4 to 512

12 25

Spreading Operation

bull Spreading means increasing the signal bandwidthbull Strictly speaking spreading includes two

operationsndash Channelisation (increases signal bandwidth) using

orthogonal codesndash Scrambling (does not affect the signal bandwidth) using

pseudo noise codes

12 26

Codes

Channellization Code Scrambling Code

Usage UL Separation of physical dataand control channels from same UEDL Separation of different userswithin one cell

UL Separation of terminalsDL Separation ofcellssectors

Length UL4-256 chipsDL4-512 chips

38400 chips

No of codes No of codes under one scrambling code= SF

UL Several millionDL 512

Code Family Orthogonal Variable Spreading Factor

Long 10ms code Gold codeShort code Extended S(2) code Family

Increase BW YES NO

12 27

UMTS Architecture

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

Cell site

Access Network

Core Network

User Equipment

12 28

UMTS Architecture

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 29

UMTS Architecture

bull User equipment-UEndash UMTS Subscriber Identity Module ndashUSIMndash Mobile Equipment- cell phone

bull UMTS Terrestrial Radio Access Networkndash Radio Network Subsystem

bull Node B- BSndash Transceiverndash Rate adaptationndash Radio resource managementndash Power control

12 30

UMTS Architecture

bull Radio Network Controller ndash RNCndash Radio access controlndash Connection controlndash Load congestion and admission controlndash Code allocation

ndash Core Networkbull MSCbull VLRbull HLRbull Gateway MSC ndash GMSC

ndash Supports circuit switched connectionsbull Serving GRPS Support Node ndash SGPRS

ndash Logical interface to UTRAN for packet transportraquo Session managementraquo Logical link management

bull Gateway GPRS Support Node ndash GGSNndash Supports packet switched transportndash This is an IP router

12 31

UMTS Protocol Architecture - User Plane

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

FP= Framing Protocol GTP-U= GPRS Tunneling Protocol-UserPDCP =Packet Data convergence Protocol

12 32

UMTS Protocol Stack

bull Radio Resource Control-RRC

bull Broadcastmulitcast control- BMC

bull Packet Data convergence Protocol- PDCPndash Header

compression

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

12 33

Packet SAR

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

12 34

Physical Layerbull The physical layer offers information transfer services to

the MAC layer These services are denoted as Transport channels (TrChrsquos) There are also Physical channels

bull Physical layer comprises following functionsndash 1048713 Various handover functionsndash 1048713 Error detection and report to higher layersndash 1048713 Multiplexing of transport channelsndash 1048713 Mapping of transport channels to physical channelsndash 1048713 Fast Close loop Power controlndash 1048713 Frequency and Time Synchronizationndash 1048713 Other responsibilities associated with transmitting and

receiving signals over the wireless mediandash Measurements

bull SIRbull Tx power Frame error rate etc

bull Physical channel is assigned a specific code

12 35

Transport amp Physical Channels

Transport Channel Physical Channel(ULDL) Dedicated Channel DCH Dedicated Physical Data Channel DPDCH

Dedicated Physical Control Channel DPCCH

(UL) Random Access Channel RACH Physical random access channel PRACH

(UL) Common packet channel CPCH Physical common packet channel PCPCH

(DL) Broadcast channel BCH Primary common control physical channel P-CCPCH

(DL) Forward access channel FACH(DL) Paging channel PCH

Secondary common control physical channel S-CCPCH

(DL) Downlink shared channel DSCH Physical downlink shared channel PDSCH

Signaling physical channels

Synchronization channel SCHCommon pilot channel CPICHAcquisition indication channel AICHPaging indication channel PICHCPCH Status indication channel CSICHCollision detectionChannel assignment indicator channel CDCA-ICH

12 36

UMTS FDD frame structure

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 37

MAC Layer

bull The MAC layer offers Data transfer to RLC and higher layers

bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically

bit rate within a predefined set per information unit delivered to the physical layer

ndash Service multiplexing on RACH FACH and dedicated channels

ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling

ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements

12 38

Physical Layer

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 39

RRC Layerbull The RRC layer offers the core network the following

servicesndash General control service which is used as an information

broadcast servicendash Notification service which is used for paging and

notification of a selected UEsndash Dedicated control service which is used for

establishmentrelease of a connection and transfer of messages using the connection

bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover

admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection

12 40

RLC Layer

bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is

appended to the information unit received from the higher layer

ndash Assured and un assured data transferbull The RLC layer comprises the following functions

ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the

WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the

control plane)ndash Duplicate detectionndash Flow controlndash Ciphering

12 41

RLC Layer-Modesbull Transparent-TM

ndash No header attachedndash SARndash SDU discard

bull Delete SDU if not sent before timer expiresndash Used for

bull Voicebull Some signaling

bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability

bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat

12 42

RLC Layer

From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the

UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

12 43

UE-Call states

bull Designed to ndash Take advantage of bursty nature of

datandash Save batter powerndash Maintains logical session and tracks

mobility but when appropriatendash releases dedicated resources to

increase overall capacityndash asleeps the UE

12 44

UE-Call states

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 45

UE-Call states

bull Idle modendash No active sessionndash UE monitors

Paging CHndash Sleeps between

paging cycles

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 46

UE-Call states

bull CELL_DCH state (Dedicated)ndash A dedicated physical

channel is allocated to the UE in uplink and downlink

ndash The UE is known on cell level according to its current active set

ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE

ndash Call typesbull Circuit Switched always in

this statebull Packet Switched in this

state if transferring large volume of data

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 47

UE-Call states

bull CELL_FACH state(Forward Access Ch)

ndash No dedicated physical channel is allocated to the UE

ndash The UE continuously monitors a FACH in the downlink

ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel

ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update

ndash Radio not put to sleepndash For packet switched sessions

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 48

UE-Call states

bull CELL_PCH state (Paging Ch)ndash No dedicated physical

channel is allocated to the UE

ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash Sleep between pagesndash A logical session is still upndash The position of the UE is

known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 49

UE-Call states

bull URA_PCH State ndash No dedicated channel is

allocated to the UEndash The UE selects a PCH with

the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state

ndash Similar to CELL_PCH state only the at the URA level

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 50

Power Control-PC

bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to

ensure that there is enough power for mobiles at the cell edge

bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control

commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command

ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break

12 51

Power Control

bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss

by means of a downlink beacon signalndash Provide a coarse initial power setting of

the mobile at the beginning of a connection

ndash Apply only prior to initiating the transmission on RACH or CPCH

12 52

Packet Access in WCDMA

bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection

bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared

bull RNC can decide when and how to send packets based on type of packet traffic

ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech

ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video

ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing

ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail

bull RNC can assign a packet to a specific channel

Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 53

Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the

downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft

handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts

bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts

bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink

orthogonal code is reserved according to maximum bit rate

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 54

Packet Access in WCDMA

bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner

bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer

bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate

bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and

bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 55

Packet Access in WCDMA

bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased

bull Advantagesndash resources are in full usage due to longer transmission

timendash small variation in interference levelndash longer uplink range due to lower bit rate

bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 56

Packet Access in WCDMA

bull Time division is normally used with shared channels and code division is normally used with dedicated channels

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 57

Packet Access in WCDMA

bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users

could be based on required transmission powerbull Users close to the BS requires less

transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate

bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput

bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 58

HSDPA amp Enhance Uplink

bull HSDPA = High Speed Downlink Packet Access

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 59

HSDPA amp Enhance Uplink

bull Remember it is better (more efficient) to have a large number of users sharing a single server

bull This lead to a desire to have fast allocation of shared resources

bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code

bull Uplink resourcesndash Interference at the BS

bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)

bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)

12 60

HSDPA amp Enhance Uplink

bull UTRAN Architecture with HSDPA and enhanced uplink

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 61

HSDPA amp Enhance Uplink

bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK

modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and

coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function

moved to Node-B (WCDMA packet scheduling was done in the RNC)

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 62

HSDPA amp Enhance Uplink

bull Gain in Performance

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 63

HSDPA

bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to

individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes

bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)

12 64

HSDPA

bull New frame structurendash Five subframesW-CDMA

framendash User data can be

assigned on a subframe basis

ndash System can adjust in 2ms

ndash Each subframe is a transmission time interval (TTI) = 2ms

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 65

HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared

resource is also in the time domain

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 66

HSDPA

bull Another view

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

Spreading Code

12 67

HSDPAbull Link Adaptation

ndash Remember the fast power control is commonly used to

bull Maintain constant EnergyNoise ratiobull Reduce effect of fading

ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant

EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 68

HSDPA

ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)

ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum

bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user

bull 1 ndash 2 Mbs closer to achievable under real conditions

12 69

HSDPA

bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE

bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms

bull CQI (0-30) each mapping into a modulation SF etc

bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression

bull

12 70

HSDPA

bull Schedulingndash The scheduler decides which user

should get access to each TTI ndash CQI provides input into a Scheduler

bull Proportional Fair (PF) Scheduler can be uses

bull Implementation Specific

12 71

HSDPA

bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number

of spreading codes limits rate not power so likely receive first transmission

ndash At greater distances move from BS see more errors IR will require additional transmission but not many

ndash HARQ only retransmit upon an ACK or NACK

12 72

HSDPA

From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007

12 73

HSDPA

bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2

ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent

Scheduling

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 5

Components

bull Base station (BS)ndash TransmitReceive over the air

interface to multiple mobile stationsndash Terminates radio signals ndash Packages information for transport to

a controller (MSC) for routingndash Sends information to Mobile Switching

Center

12 6

Components

bull Mobile Switching Center (MSC)ndash Connects to many BSsndash Performs call set upndash Provides routing functionsndash Typically associated with voice callsndash Sometines called Mobile Telecommunications Switching Office

(MST0)bull Home location register (HLR)

ndash Wireless service provider (WSP) maintains a databasebull Subscriber personal information eg phone number mobile

identification number electronic serial number (ESN) of phone bull Service Profilebull Current location of subscriber

ndash One HLR may serve several MSCsbull Visitor location register (VLR)

ndash Data base containing temporary information of subscribersndash For subscribers away from home service areandash VRL information retrieved from the HLR

12 7

Process

bull Registrationndash Turn on cell phonendash BS continually transmit

signals on control channelsndash Cell phone scans for

strongest signalndash Cell phone decodes control

signal to determinebull System Idbull Initial Tx power settingbull Radio channels to use for

further communicationsbull Cell phone registers with

network bull Note as the MS moves it

may need to cancel registration in old area and re-register in new area

12 8

Process

bull Mobile Call Initiationndash To make a call the

mobile keys the phone and hits send

ndash Phone transmitted over preselected control channel

ndash The BS relays information to the MSC

ndash MSC looking into the control message to get the and processes the call ie does the routing

12 9

Process

bull Call initiation to mobilendash Call routed to home MSCndash MSC checks HLR to

determine location of subscriber

ndash MSC has current visiting MSC stored in the HLR

ndash Home MSC communicates with the visiting MSC to rout the call

ndash The MSC sends a paging message to the paging message to BS

ndash The BS then send the paging message on to the subscriber on an assigned control (paging) channel

12 10

Process

bull Call acceptedndash MS sees the paging

signal and responds to the BS

ndash The BS send response to the MSC

ndash The MSC sets up the call to the BS

ndash The MSC also assigns a air interface channel for the BS to use for the call

ndash The MS communicates of the assigned channel

bull Here the call is between two mobiles

bull The communications is monitored for the ongoing call

12 11

Processbull Handoff (or handover)

ndash MS continually scans for control signals of BS

ndash Knowledge of the results of scans is used by MSC eg power of control signal drops below some threshold

ndash Upon that event the MSC will initiate a handoff procedure

ndash Handoff procedures can be implemented transparent to the users no interruption

ndash The handoff procedure tells the MS to use a specific channel to communicate with the new BS

12 12

Process

bull Handoffsndash Hard communications with old BS is terminated and

a new communications to a new BS is establishedndash Soft

bull Soft mobile station temporarily connected to more than one base station simultaneously

bull Softer mobile station temporarily connected to more than one sector of the same base station simultaneously

bull Soft-softer mobile station temporarily connected to more than one sector of the same base station and more than one base station simultaneously

bull Provides diversitybull Occurs at boundaries of sectorscells

12 13

Other Functions

bull Call blockingndash if all traffic channels busy

bull Call terminationndash when user hangs up

bull Call dropndash when BS cannot maintain required signal

strength

12 14

Other Functions Power control CDMA

bull Purposendash Removes near far effectndash Mitigates fadingndash Compensates changes in propagation conditionsndash In the system level

bull decrease interference from other usersbull increase capacity of the system

bull Uplinkndash Power control in uplink must make signal powers

from different users nearly equal in order to maximize the total capacity in the cell

bull Downlinkndash In downlink the power control must keep the signal

at minimal required level in order to decrease the interference to users in other cells

12 15

Other Functions Power control CDMA

bull Typesndash Open loop

bull set initial power for MSbull Each MS sets power based on individual

measurementsbull Coarse scale

ndash Closed loopbull BS knows receive power from each MSbull BS can tell each MS to set its power to achieve

system goalsbull Fast power control can mitigate fast fadingbull Three steps

ndash Transmissionndash Measurementndash Feedback

12 16

3G

bull 1G Analog Cellular Phones Needs a modem 96 kbps max

bull 2G Digital Cellular Phones No modem required 193 kbps max

bull 25G General Packet Radio Service (GPRS) 144kbps Data only

bull 3G Future high-speed data with Voice 64 kbps to 2 Mbpsndash W-CDMAUMTS (Universal Mobile

Telecommunications Systemndash CDMA2000

12 17

Organizations

ndash 3GPP 3rd Generation Partnership Project

ndash 3GPP is responsible for writing and maintaining the UMTS specifications

ndash hellip CDMA2000 hellipndash Internet Engineering Task Force (IETF)

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 18

3G- Advantages

3G phones promise - bull Improved digital voice communications bull Larger Bandwidth ndash Higher Data ratebull Greater subscriber capacity bull Fast packet-based data services like e-mail

short message service (SMS) and Internet access at broadband speeds

bull Most carriers also expect consumers to want - ndash location services ndash interactive gaming ndash streaming video ndash home monitoring and control ndash and who knows what else while being fully mobile

anywhere in the world

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 19

3G Capabilitiesbull Voice quality comparable to the public

switched telephone networkbull 144 Kbps- user in high-speed motor vehiclesbull 384 Kbps- pedestrians standing or moving

slowly over small areasbull Up to 2 Mbps- fixed applications like office usebull Symmetricalasymmetrical data transmission

ratesbull Support for both packet switched and circuit

switched data services like Internet Protocol (IP) traffic and real time video

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 20

Technologies

bull 3G is superior to the other digital standards like-ndash GSM (Global System for Mobile) communications standard

used worldwide ndash And IS-136 TDMA standard used primarily in North America ndash IS-95 CDMA systems

bull 3G Technologies-

ndash WCDMA or UMTS-FDD (Universal Mobile Telecommunications System - Frequency Division Duplex)---Direct Spread

ndash CDMA2000 - 1x-EvDOEvDV---Multi carrier

ndash UMTS ndash TDD (Time Division Duplex) or TD-SCDMA (Time Division - Synchronous Code Division Multiple Access) ---Time Code

ndash CDMA2000 and WCDMA or UMTS-FDD have similar architectures

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 21

Evolution Paths

25G2G 3G

cdmaOneIS-95A

TDMA

cdmaOneIS-95B Cdma2000 1X

Cdma20001xEV-DV

Cdma20001xEV-DO

GSMGPRS

EDGE WCDMA

GSM Map Core Network

IS-41 Core Network

25G2G 3G

cdmaOneIS-95A

TDMA

cdmaOneIS-95B Cdma2000 1X

Cdma20001xEV-DV

Cdma20001xEV-DO

GSMGPRS

EDGE WCDMA

GSM Map Core Network

IS-41 Core Network

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 22

WCDMA

bull Spectrumndash 1920 MHz ndash 1980 MHz (uplink)ndash 2110 MHz ndash 2170 MHz (downlink)orndash 1850 MHz ndash 1910 MHz (uplink)ndash 1930 MHz ndash 1990 MHz (downlink)ndash Channel Spacing 5 Mhz

bull WCDMA is connected to the FDD Phy and the associated protocols Focus here

bull UTRAN-Universal Terrestrial Radio Access Network- is associated with the WCDMA radio Access Network

bull UMTS refers to the whole network

12 23

UMTS-FDD WCDMA

bull Wideband Direct Sequence Code Division Multiple Access

bull Does not assign a specific frequency to each user Instead every channel uses the full available spectrum

bull Individual conversations are encoded with a pseudo-random digital sequence

bull See httpwwwumtsworldcomtechnologyoverviewhtm

12 24

WCDMA Parameters

Channel BW 5 MHz

Forward RF Channel Structure Direct Spread

Chip Rate 384 Mcps

Frame Length 10 ms (38400 chips)

No of slotsframe 15

No of chipsslot 2560chips (Max 2560 bits)

Power Control Open and fast close loop (16 KHz)

Uplink Spreading Factor 4 to 256

Downlink Spreading Factor 4 to 512

12 25

Spreading Operation

bull Spreading means increasing the signal bandwidthbull Strictly speaking spreading includes two

operationsndash Channelisation (increases signal bandwidth) using

orthogonal codesndash Scrambling (does not affect the signal bandwidth) using

pseudo noise codes

12 26

Codes

Channellization Code Scrambling Code

Usage UL Separation of physical dataand control channels from same UEDL Separation of different userswithin one cell

UL Separation of terminalsDL Separation ofcellssectors

Length UL4-256 chipsDL4-512 chips

38400 chips

No of codes No of codes under one scrambling code= SF

UL Several millionDL 512

Code Family Orthogonal Variable Spreading Factor

Long 10ms code Gold codeShort code Extended S(2) code Family

Increase BW YES NO

12 27

UMTS Architecture

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

Cell site

Access Network

Core Network

User Equipment

12 28

UMTS Architecture

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 29

UMTS Architecture

bull User equipment-UEndash UMTS Subscriber Identity Module ndashUSIMndash Mobile Equipment- cell phone

bull UMTS Terrestrial Radio Access Networkndash Radio Network Subsystem

bull Node B- BSndash Transceiverndash Rate adaptationndash Radio resource managementndash Power control

12 30

UMTS Architecture

bull Radio Network Controller ndash RNCndash Radio access controlndash Connection controlndash Load congestion and admission controlndash Code allocation

ndash Core Networkbull MSCbull VLRbull HLRbull Gateway MSC ndash GMSC

ndash Supports circuit switched connectionsbull Serving GRPS Support Node ndash SGPRS

ndash Logical interface to UTRAN for packet transportraquo Session managementraquo Logical link management

bull Gateway GPRS Support Node ndash GGSNndash Supports packet switched transportndash This is an IP router

12 31

UMTS Protocol Architecture - User Plane

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

FP= Framing Protocol GTP-U= GPRS Tunneling Protocol-UserPDCP =Packet Data convergence Protocol

12 32

UMTS Protocol Stack

bull Radio Resource Control-RRC

bull Broadcastmulitcast control- BMC

bull Packet Data convergence Protocol- PDCPndash Header

compression

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

12 33

Packet SAR

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

12 34

Physical Layerbull The physical layer offers information transfer services to

the MAC layer These services are denoted as Transport channels (TrChrsquos) There are also Physical channels

bull Physical layer comprises following functionsndash 1048713 Various handover functionsndash 1048713 Error detection and report to higher layersndash 1048713 Multiplexing of transport channelsndash 1048713 Mapping of transport channels to physical channelsndash 1048713 Fast Close loop Power controlndash 1048713 Frequency and Time Synchronizationndash 1048713 Other responsibilities associated with transmitting and

receiving signals over the wireless mediandash Measurements

bull SIRbull Tx power Frame error rate etc

bull Physical channel is assigned a specific code

12 35

Transport amp Physical Channels

Transport Channel Physical Channel(ULDL) Dedicated Channel DCH Dedicated Physical Data Channel DPDCH

Dedicated Physical Control Channel DPCCH

(UL) Random Access Channel RACH Physical random access channel PRACH

(UL) Common packet channel CPCH Physical common packet channel PCPCH

(DL) Broadcast channel BCH Primary common control physical channel P-CCPCH

(DL) Forward access channel FACH(DL) Paging channel PCH

Secondary common control physical channel S-CCPCH

(DL) Downlink shared channel DSCH Physical downlink shared channel PDSCH

Signaling physical channels

Synchronization channel SCHCommon pilot channel CPICHAcquisition indication channel AICHPaging indication channel PICHCPCH Status indication channel CSICHCollision detectionChannel assignment indicator channel CDCA-ICH

12 36

UMTS FDD frame structure

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 37

MAC Layer

bull The MAC layer offers Data transfer to RLC and higher layers

bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically

bit rate within a predefined set per information unit delivered to the physical layer

ndash Service multiplexing on RACH FACH and dedicated channels

ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling

ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements

12 38

Physical Layer

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 39

RRC Layerbull The RRC layer offers the core network the following

servicesndash General control service which is used as an information

broadcast servicendash Notification service which is used for paging and

notification of a selected UEsndash Dedicated control service which is used for

establishmentrelease of a connection and transfer of messages using the connection

bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover

admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection

12 40

RLC Layer

bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is

appended to the information unit received from the higher layer

ndash Assured and un assured data transferbull The RLC layer comprises the following functions

ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the

WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the

control plane)ndash Duplicate detectionndash Flow controlndash Ciphering

12 41

RLC Layer-Modesbull Transparent-TM

ndash No header attachedndash SARndash SDU discard

bull Delete SDU if not sent before timer expiresndash Used for

bull Voicebull Some signaling

bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability

bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat

12 42

RLC Layer

From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the

UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

12 43

UE-Call states

bull Designed to ndash Take advantage of bursty nature of

datandash Save batter powerndash Maintains logical session and tracks

mobility but when appropriatendash releases dedicated resources to

increase overall capacityndash asleeps the UE

12 44

UE-Call states

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 45

UE-Call states

bull Idle modendash No active sessionndash UE monitors

Paging CHndash Sleeps between

paging cycles

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 46

UE-Call states

bull CELL_DCH state (Dedicated)ndash A dedicated physical

channel is allocated to the UE in uplink and downlink

ndash The UE is known on cell level according to its current active set

ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE

ndash Call typesbull Circuit Switched always in

this statebull Packet Switched in this

state if transferring large volume of data

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 47

UE-Call states

bull CELL_FACH state(Forward Access Ch)

ndash No dedicated physical channel is allocated to the UE

ndash The UE continuously monitors a FACH in the downlink

ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel

ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update

ndash Radio not put to sleepndash For packet switched sessions

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 48

UE-Call states

bull CELL_PCH state (Paging Ch)ndash No dedicated physical

channel is allocated to the UE

ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash Sleep between pagesndash A logical session is still upndash The position of the UE is

known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 49

UE-Call states

bull URA_PCH State ndash No dedicated channel is

allocated to the UEndash The UE selects a PCH with

the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state

ndash Similar to CELL_PCH state only the at the URA level

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 50

Power Control-PC

bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to

ensure that there is enough power for mobiles at the cell edge

bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control

commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command

ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break

12 51

Power Control

bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss

by means of a downlink beacon signalndash Provide a coarse initial power setting of

the mobile at the beginning of a connection

ndash Apply only prior to initiating the transmission on RACH or CPCH

12 52

Packet Access in WCDMA

bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection

bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared

bull RNC can decide when and how to send packets based on type of packet traffic

ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech

ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video

ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing

ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail

bull RNC can assign a packet to a specific channel

Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 53

Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the

downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft

handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts

bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts

bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink

orthogonal code is reserved according to maximum bit rate

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 54

Packet Access in WCDMA

bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner

bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer

bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate

bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and

bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 55

Packet Access in WCDMA

bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased

bull Advantagesndash resources are in full usage due to longer transmission

timendash small variation in interference levelndash longer uplink range due to lower bit rate

bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 56

Packet Access in WCDMA

bull Time division is normally used with shared channels and code division is normally used with dedicated channels

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 57

Packet Access in WCDMA

bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users

could be based on required transmission powerbull Users close to the BS requires less

transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate

bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput

bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 58

HSDPA amp Enhance Uplink

bull HSDPA = High Speed Downlink Packet Access

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 59

HSDPA amp Enhance Uplink

bull Remember it is better (more efficient) to have a large number of users sharing a single server

bull This lead to a desire to have fast allocation of shared resources

bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code

bull Uplink resourcesndash Interference at the BS

bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)

bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)

12 60

HSDPA amp Enhance Uplink

bull UTRAN Architecture with HSDPA and enhanced uplink

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 61

HSDPA amp Enhance Uplink

bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK

modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and

coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function

moved to Node-B (WCDMA packet scheduling was done in the RNC)

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 62

HSDPA amp Enhance Uplink

bull Gain in Performance

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 63

HSDPA

bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to

individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes

bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)

12 64

HSDPA

bull New frame structurendash Five subframesW-CDMA

framendash User data can be

assigned on a subframe basis

ndash System can adjust in 2ms

ndash Each subframe is a transmission time interval (TTI) = 2ms

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 65

HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared

resource is also in the time domain

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 66

HSDPA

bull Another view

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

Spreading Code

12 67

HSDPAbull Link Adaptation

ndash Remember the fast power control is commonly used to

bull Maintain constant EnergyNoise ratiobull Reduce effect of fading

ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant

EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 68

HSDPA

ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)

ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum

bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user

bull 1 ndash 2 Mbs closer to achievable under real conditions

12 69

HSDPA

bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE

bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms

bull CQI (0-30) each mapping into a modulation SF etc

bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression

bull

12 70

HSDPA

bull Schedulingndash The scheduler decides which user

should get access to each TTI ndash CQI provides input into a Scheduler

bull Proportional Fair (PF) Scheduler can be uses

bull Implementation Specific

12 71

HSDPA

bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number

of spreading codes limits rate not power so likely receive first transmission

ndash At greater distances move from BS see more errors IR will require additional transmission but not many

ndash HARQ only retransmit upon an ACK or NACK

12 72

HSDPA

From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007

12 73

HSDPA

bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2

ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent

Scheduling

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 6

Components

bull Mobile Switching Center (MSC)ndash Connects to many BSsndash Performs call set upndash Provides routing functionsndash Typically associated with voice callsndash Sometines called Mobile Telecommunications Switching Office

(MST0)bull Home location register (HLR)

ndash Wireless service provider (WSP) maintains a databasebull Subscriber personal information eg phone number mobile

identification number electronic serial number (ESN) of phone bull Service Profilebull Current location of subscriber

ndash One HLR may serve several MSCsbull Visitor location register (VLR)

ndash Data base containing temporary information of subscribersndash For subscribers away from home service areandash VRL information retrieved from the HLR

12 7

Process

bull Registrationndash Turn on cell phonendash BS continually transmit

signals on control channelsndash Cell phone scans for

strongest signalndash Cell phone decodes control

signal to determinebull System Idbull Initial Tx power settingbull Radio channels to use for

further communicationsbull Cell phone registers with

network bull Note as the MS moves it

may need to cancel registration in old area and re-register in new area

12 8

Process

bull Mobile Call Initiationndash To make a call the

mobile keys the phone and hits send

ndash Phone transmitted over preselected control channel

ndash The BS relays information to the MSC

ndash MSC looking into the control message to get the and processes the call ie does the routing

12 9

Process

bull Call initiation to mobilendash Call routed to home MSCndash MSC checks HLR to

determine location of subscriber

ndash MSC has current visiting MSC stored in the HLR

ndash Home MSC communicates with the visiting MSC to rout the call

ndash The MSC sends a paging message to the paging message to BS

ndash The BS then send the paging message on to the subscriber on an assigned control (paging) channel

12 10

Process

bull Call acceptedndash MS sees the paging

signal and responds to the BS

ndash The BS send response to the MSC

ndash The MSC sets up the call to the BS

ndash The MSC also assigns a air interface channel for the BS to use for the call

ndash The MS communicates of the assigned channel

bull Here the call is between two mobiles

bull The communications is monitored for the ongoing call

12 11

Processbull Handoff (or handover)

ndash MS continually scans for control signals of BS

ndash Knowledge of the results of scans is used by MSC eg power of control signal drops below some threshold

ndash Upon that event the MSC will initiate a handoff procedure

ndash Handoff procedures can be implemented transparent to the users no interruption

ndash The handoff procedure tells the MS to use a specific channel to communicate with the new BS

12 12

Process

bull Handoffsndash Hard communications with old BS is terminated and

a new communications to a new BS is establishedndash Soft

bull Soft mobile station temporarily connected to more than one base station simultaneously

bull Softer mobile station temporarily connected to more than one sector of the same base station simultaneously

bull Soft-softer mobile station temporarily connected to more than one sector of the same base station and more than one base station simultaneously

bull Provides diversitybull Occurs at boundaries of sectorscells

12 13

Other Functions

bull Call blockingndash if all traffic channels busy

bull Call terminationndash when user hangs up

bull Call dropndash when BS cannot maintain required signal

strength

12 14

Other Functions Power control CDMA

bull Purposendash Removes near far effectndash Mitigates fadingndash Compensates changes in propagation conditionsndash In the system level

bull decrease interference from other usersbull increase capacity of the system

bull Uplinkndash Power control in uplink must make signal powers

from different users nearly equal in order to maximize the total capacity in the cell

bull Downlinkndash In downlink the power control must keep the signal

at minimal required level in order to decrease the interference to users in other cells

12 15

Other Functions Power control CDMA

bull Typesndash Open loop

bull set initial power for MSbull Each MS sets power based on individual

measurementsbull Coarse scale

ndash Closed loopbull BS knows receive power from each MSbull BS can tell each MS to set its power to achieve

system goalsbull Fast power control can mitigate fast fadingbull Three steps

ndash Transmissionndash Measurementndash Feedback

12 16

3G

bull 1G Analog Cellular Phones Needs a modem 96 kbps max

bull 2G Digital Cellular Phones No modem required 193 kbps max

bull 25G General Packet Radio Service (GPRS) 144kbps Data only

bull 3G Future high-speed data with Voice 64 kbps to 2 Mbpsndash W-CDMAUMTS (Universal Mobile

Telecommunications Systemndash CDMA2000

12 17

Organizations

ndash 3GPP 3rd Generation Partnership Project

ndash 3GPP is responsible for writing and maintaining the UMTS specifications

ndash hellip CDMA2000 hellipndash Internet Engineering Task Force (IETF)

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 18

3G- Advantages

3G phones promise - bull Improved digital voice communications bull Larger Bandwidth ndash Higher Data ratebull Greater subscriber capacity bull Fast packet-based data services like e-mail

short message service (SMS) and Internet access at broadband speeds

bull Most carriers also expect consumers to want - ndash location services ndash interactive gaming ndash streaming video ndash home monitoring and control ndash and who knows what else while being fully mobile

anywhere in the world

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 19

3G Capabilitiesbull Voice quality comparable to the public

switched telephone networkbull 144 Kbps- user in high-speed motor vehiclesbull 384 Kbps- pedestrians standing or moving

slowly over small areasbull Up to 2 Mbps- fixed applications like office usebull Symmetricalasymmetrical data transmission

ratesbull Support for both packet switched and circuit

switched data services like Internet Protocol (IP) traffic and real time video

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 20

Technologies

bull 3G is superior to the other digital standards like-ndash GSM (Global System for Mobile) communications standard

used worldwide ndash And IS-136 TDMA standard used primarily in North America ndash IS-95 CDMA systems

bull 3G Technologies-

ndash WCDMA or UMTS-FDD (Universal Mobile Telecommunications System - Frequency Division Duplex)---Direct Spread

ndash CDMA2000 - 1x-EvDOEvDV---Multi carrier

ndash UMTS ndash TDD (Time Division Duplex) or TD-SCDMA (Time Division - Synchronous Code Division Multiple Access) ---Time Code

ndash CDMA2000 and WCDMA or UMTS-FDD have similar architectures

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 21

Evolution Paths

25G2G 3G

cdmaOneIS-95A

TDMA

cdmaOneIS-95B Cdma2000 1X

Cdma20001xEV-DV

Cdma20001xEV-DO

GSMGPRS

EDGE WCDMA

GSM Map Core Network

IS-41 Core Network

25G2G 3G

cdmaOneIS-95A

TDMA

cdmaOneIS-95B Cdma2000 1X

Cdma20001xEV-DV

Cdma20001xEV-DO

GSMGPRS

EDGE WCDMA

GSM Map Core Network

IS-41 Core Network

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 22

WCDMA

bull Spectrumndash 1920 MHz ndash 1980 MHz (uplink)ndash 2110 MHz ndash 2170 MHz (downlink)orndash 1850 MHz ndash 1910 MHz (uplink)ndash 1930 MHz ndash 1990 MHz (downlink)ndash Channel Spacing 5 Mhz

bull WCDMA is connected to the FDD Phy and the associated protocols Focus here

bull UTRAN-Universal Terrestrial Radio Access Network- is associated with the WCDMA radio Access Network

bull UMTS refers to the whole network

12 23

UMTS-FDD WCDMA

bull Wideband Direct Sequence Code Division Multiple Access

bull Does not assign a specific frequency to each user Instead every channel uses the full available spectrum

bull Individual conversations are encoded with a pseudo-random digital sequence

bull See httpwwwumtsworldcomtechnologyoverviewhtm

12 24

WCDMA Parameters

Channel BW 5 MHz

Forward RF Channel Structure Direct Spread

Chip Rate 384 Mcps

Frame Length 10 ms (38400 chips)

No of slotsframe 15

No of chipsslot 2560chips (Max 2560 bits)

Power Control Open and fast close loop (16 KHz)

Uplink Spreading Factor 4 to 256

Downlink Spreading Factor 4 to 512

12 25

Spreading Operation

bull Spreading means increasing the signal bandwidthbull Strictly speaking spreading includes two

operationsndash Channelisation (increases signal bandwidth) using

orthogonal codesndash Scrambling (does not affect the signal bandwidth) using

pseudo noise codes

12 26

Codes

Channellization Code Scrambling Code

Usage UL Separation of physical dataand control channels from same UEDL Separation of different userswithin one cell

UL Separation of terminalsDL Separation ofcellssectors

Length UL4-256 chipsDL4-512 chips

38400 chips

No of codes No of codes under one scrambling code= SF

UL Several millionDL 512

Code Family Orthogonal Variable Spreading Factor

Long 10ms code Gold codeShort code Extended S(2) code Family

Increase BW YES NO

12 27

UMTS Architecture

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

Cell site

Access Network

Core Network

User Equipment

12 28

UMTS Architecture

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 29

UMTS Architecture

bull User equipment-UEndash UMTS Subscriber Identity Module ndashUSIMndash Mobile Equipment- cell phone

bull UMTS Terrestrial Radio Access Networkndash Radio Network Subsystem

bull Node B- BSndash Transceiverndash Rate adaptationndash Radio resource managementndash Power control

12 30

UMTS Architecture

bull Radio Network Controller ndash RNCndash Radio access controlndash Connection controlndash Load congestion and admission controlndash Code allocation

ndash Core Networkbull MSCbull VLRbull HLRbull Gateway MSC ndash GMSC

ndash Supports circuit switched connectionsbull Serving GRPS Support Node ndash SGPRS

ndash Logical interface to UTRAN for packet transportraquo Session managementraquo Logical link management

bull Gateway GPRS Support Node ndash GGSNndash Supports packet switched transportndash This is an IP router

12 31

UMTS Protocol Architecture - User Plane

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

FP= Framing Protocol GTP-U= GPRS Tunneling Protocol-UserPDCP =Packet Data convergence Protocol

12 32

UMTS Protocol Stack

bull Radio Resource Control-RRC

bull Broadcastmulitcast control- BMC

bull Packet Data convergence Protocol- PDCPndash Header

compression

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

12 33

Packet SAR

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

12 34

Physical Layerbull The physical layer offers information transfer services to

the MAC layer These services are denoted as Transport channels (TrChrsquos) There are also Physical channels

bull Physical layer comprises following functionsndash 1048713 Various handover functionsndash 1048713 Error detection and report to higher layersndash 1048713 Multiplexing of transport channelsndash 1048713 Mapping of transport channels to physical channelsndash 1048713 Fast Close loop Power controlndash 1048713 Frequency and Time Synchronizationndash 1048713 Other responsibilities associated with transmitting and

receiving signals over the wireless mediandash Measurements

bull SIRbull Tx power Frame error rate etc

bull Physical channel is assigned a specific code

12 35

Transport amp Physical Channels

Transport Channel Physical Channel(ULDL) Dedicated Channel DCH Dedicated Physical Data Channel DPDCH

Dedicated Physical Control Channel DPCCH

(UL) Random Access Channel RACH Physical random access channel PRACH

(UL) Common packet channel CPCH Physical common packet channel PCPCH

(DL) Broadcast channel BCH Primary common control physical channel P-CCPCH

(DL) Forward access channel FACH(DL) Paging channel PCH

Secondary common control physical channel S-CCPCH

(DL) Downlink shared channel DSCH Physical downlink shared channel PDSCH

Signaling physical channels

Synchronization channel SCHCommon pilot channel CPICHAcquisition indication channel AICHPaging indication channel PICHCPCH Status indication channel CSICHCollision detectionChannel assignment indicator channel CDCA-ICH

12 36

UMTS FDD frame structure

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 37

MAC Layer

bull The MAC layer offers Data transfer to RLC and higher layers

bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically

bit rate within a predefined set per information unit delivered to the physical layer

ndash Service multiplexing on RACH FACH and dedicated channels

ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling

ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements

12 38

Physical Layer

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 39

RRC Layerbull The RRC layer offers the core network the following

servicesndash General control service which is used as an information

broadcast servicendash Notification service which is used for paging and

notification of a selected UEsndash Dedicated control service which is used for

establishmentrelease of a connection and transfer of messages using the connection

bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover

admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection

12 40

RLC Layer

bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is

appended to the information unit received from the higher layer

ndash Assured and un assured data transferbull The RLC layer comprises the following functions

ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the

WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the

control plane)ndash Duplicate detectionndash Flow controlndash Ciphering

12 41

RLC Layer-Modesbull Transparent-TM

ndash No header attachedndash SARndash SDU discard

bull Delete SDU if not sent before timer expiresndash Used for

bull Voicebull Some signaling

bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability

bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat

12 42

RLC Layer

From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the

UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

12 43

UE-Call states

bull Designed to ndash Take advantage of bursty nature of

datandash Save batter powerndash Maintains logical session and tracks

mobility but when appropriatendash releases dedicated resources to

increase overall capacityndash asleeps the UE

12 44

UE-Call states

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 45

UE-Call states

bull Idle modendash No active sessionndash UE monitors

Paging CHndash Sleeps between

paging cycles

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 46

UE-Call states

bull CELL_DCH state (Dedicated)ndash A dedicated physical

channel is allocated to the UE in uplink and downlink

ndash The UE is known on cell level according to its current active set

ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE

ndash Call typesbull Circuit Switched always in

this statebull Packet Switched in this

state if transferring large volume of data

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 47

UE-Call states

bull CELL_FACH state(Forward Access Ch)

ndash No dedicated physical channel is allocated to the UE

ndash The UE continuously monitors a FACH in the downlink

ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel

ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update

ndash Radio not put to sleepndash For packet switched sessions

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 48

UE-Call states

bull CELL_PCH state (Paging Ch)ndash No dedicated physical

channel is allocated to the UE

ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash Sleep between pagesndash A logical session is still upndash The position of the UE is

known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 49

UE-Call states

bull URA_PCH State ndash No dedicated channel is

allocated to the UEndash The UE selects a PCH with

the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state

ndash Similar to CELL_PCH state only the at the URA level

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 50

Power Control-PC

bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to

ensure that there is enough power for mobiles at the cell edge

bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control

commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command

ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break

12 51

Power Control

bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss

by means of a downlink beacon signalndash Provide a coarse initial power setting of

the mobile at the beginning of a connection

ndash Apply only prior to initiating the transmission on RACH or CPCH

12 52

Packet Access in WCDMA

bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection

bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared

bull RNC can decide when and how to send packets based on type of packet traffic

ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech

ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video

ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing

ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail

bull RNC can assign a packet to a specific channel

Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 53

Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the

downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft

handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts

bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts

bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink

orthogonal code is reserved according to maximum bit rate

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 54

Packet Access in WCDMA

bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner

bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer

bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate

bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and

bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 55

Packet Access in WCDMA

bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased

bull Advantagesndash resources are in full usage due to longer transmission

timendash small variation in interference levelndash longer uplink range due to lower bit rate

bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 56

Packet Access in WCDMA

bull Time division is normally used with shared channels and code division is normally used with dedicated channels

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 57

Packet Access in WCDMA

bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users

could be based on required transmission powerbull Users close to the BS requires less

transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate

bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput

bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 58

HSDPA amp Enhance Uplink

bull HSDPA = High Speed Downlink Packet Access

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 59

HSDPA amp Enhance Uplink

bull Remember it is better (more efficient) to have a large number of users sharing a single server

bull This lead to a desire to have fast allocation of shared resources

bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code

bull Uplink resourcesndash Interference at the BS

bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)

bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)

12 60

HSDPA amp Enhance Uplink

bull UTRAN Architecture with HSDPA and enhanced uplink

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 61

HSDPA amp Enhance Uplink

bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK

modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and

coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function

moved to Node-B (WCDMA packet scheduling was done in the RNC)

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 62

HSDPA amp Enhance Uplink

bull Gain in Performance

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 63

HSDPA

bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to

individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes

bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)

12 64

HSDPA

bull New frame structurendash Five subframesW-CDMA

framendash User data can be

assigned on a subframe basis

ndash System can adjust in 2ms

ndash Each subframe is a transmission time interval (TTI) = 2ms

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 65

HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared

resource is also in the time domain

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 66

HSDPA

bull Another view

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

Spreading Code

12 67

HSDPAbull Link Adaptation

ndash Remember the fast power control is commonly used to

bull Maintain constant EnergyNoise ratiobull Reduce effect of fading

ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant

EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 68

HSDPA

ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)

ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum

bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user

bull 1 ndash 2 Mbs closer to achievable under real conditions

12 69

HSDPA

bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE

bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms

bull CQI (0-30) each mapping into a modulation SF etc

bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression

bull

12 70

HSDPA

bull Schedulingndash The scheduler decides which user

should get access to each TTI ndash CQI provides input into a Scheduler

bull Proportional Fair (PF) Scheduler can be uses

bull Implementation Specific

12 71

HSDPA

bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number

of spreading codes limits rate not power so likely receive first transmission

ndash At greater distances move from BS see more errors IR will require additional transmission but not many

ndash HARQ only retransmit upon an ACK or NACK

12 72

HSDPA

From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007

12 73

HSDPA

bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2

ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent

Scheduling

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 7

Process

bull Registrationndash Turn on cell phonendash BS continually transmit

signals on control channelsndash Cell phone scans for

strongest signalndash Cell phone decodes control

signal to determinebull System Idbull Initial Tx power settingbull Radio channels to use for

further communicationsbull Cell phone registers with

network bull Note as the MS moves it

may need to cancel registration in old area and re-register in new area

12 8

Process

bull Mobile Call Initiationndash To make a call the

mobile keys the phone and hits send

ndash Phone transmitted over preselected control channel

ndash The BS relays information to the MSC

ndash MSC looking into the control message to get the and processes the call ie does the routing

12 9

Process

bull Call initiation to mobilendash Call routed to home MSCndash MSC checks HLR to

determine location of subscriber

ndash MSC has current visiting MSC stored in the HLR

ndash Home MSC communicates with the visiting MSC to rout the call

ndash The MSC sends a paging message to the paging message to BS

ndash The BS then send the paging message on to the subscriber on an assigned control (paging) channel

12 10

Process

bull Call acceptedndash MS sees the paging

signal and responds to the BS

ndash The BS send response to the MSC

ndash The MSC sets up the call to the BS

ndash The MSC also assigns a air interface channel for the BS to use for the call

ndash The MS communicates of the assigned channel

bull Here the call is between two mobiles

bull The communications is monitored for the ongoing call

12 11

Processbull Handoff (or handover)

ndash MS continually scans for control signals of BS

ndash Knowledge of the results of scans is used by MSC eg power of control signal drops below some threshold

ndash Upon that event the MSC will initiate a handoff procedure

ndash Handoff procedures can be implemented transparent to the users no interruption

ndash The handoff procedure tells the MS to use a specific channel to communicate with the new BS

12 12

Process

bull Handoffsndash Hard communications with old BS is terminated and

a new communications to a new BS is establishedndash Soft

bull Soft mobile station temporarily connected to more than one base station simultaneously

bull Softer mobile station temporarily connected to more than one sector of the same base station simultaneously

bull Soft-softer mobile station temporarily connected to more than one sector of the same base station and more than one base station simultaneously

bull Provides diversitybull Occurs at boundaries of sectorscells

12 13

Other Functions

bull Call blockingndash if all traffic channels busy

bull Call terminationndash when user hangs up

bull Call dropndash when BS cannot maintain required signal

strength

12 14

Other Functions Power control CDMA

bull Purposendash Removes near far effectndash Mitigates fadingndash Compensates changes in propagation conditionsndash In the system level

bull decrease interference from other usersbull increase capacity of the system

bull Uplinkndash Power control in uplink must make signal powers

from different users nearly equal in order to maximize the total capacity in the cell

bull Downlinkndash In downlink the power control must keep the signal

at minimal required level in order to decrease the interference to users in other cells

12 15

Other Functions Power control CDMA

bull Typesndash Open loop

bull set initial power for MSbull Each MS sets power based on individual

measurementsbull Coarse scale

ndash Closed loopbull BS knows receive power from each MSbull BS can tell each MS to set its power to achieve

system goalsbull Fast power control can mitigate fast fadingbull Three steps

ndash Transmissionndash Measurementndash Feedback

12 16

3G

bull 1G Analog Cellular Phones Needs a modem 96 kbps max

bull 2G Digital Cellular Phones No modem required 193 kbps max

bull 25G General Packet Radio Service (GPRS) 144kbps Data only

bull 3G Future high-speed data with Voice 64 kbps to 2 Mbpsndash W-CDMAUMTS (Universal Mobile

Telecommunications Systemndash CDMA2000

12 17

Organizations

ndash 3GPP 3rd Generation Partnership Project

ndash 3GPP is responsible for writing and maintaining the UMTS specifications

ndash hellip CDMA2000 hellipndash Internet Engineering Task Force (IETF)

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 18

3G- Advantages

3G phones promise - bull Improved digital voice communications bull Larger Bandwidth ndash Higher Data ratebull Greater subscriber capacity bull Fast packet-based data services like e-mail

short message service (SMS) and Internet access at broadband speeds

bull Most carriers also expect consumers to want - ndash location services ndash interactive gaming ndash streaming video ndash home monitoring and control ndash and who knows what else while being fully mobile

anywhere in the world

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 19

3G Capabilitiesbull Voice quality comparable to the public

switched telephone networkbull 144 Kbps- user in high-speed motor vehiclesbull 384 Kbps- pedestrians standing or moving

slowly over small areasbull Up to 2 Mbps- fixed applications like office usebull Symmetricalasymmetrical data transmission

ratesbull Support for both packet switched and circuit

switched data services like Internet Protocol (IP) traffic and real time video

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 20

Technologies

bull 3G is superior to the other digital standards like-ndash GSM (Global System for Mobile) communications standard

used worldwide ndash And IS-136 TDMA standard used primarily in North America ndash IS-95 CDMA systems

bull 3G Technologies-

ndash WCDMA or UMTS-FDD (Universal Mobile Telecommunications System - Frequency Division Duplex)---Direct Spread

ndash CDMA2000 - 1x-EvDOEvDV---Multi carrier

ndash UMTS ndash TDD (Time Division Duplex) or TD-SCDMA (Time Division - Synchronous Code Division Multiple Access) ---Time Code

ndash CDMA2000 and WCDMA or UMTS-FDD have similar architectures

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 21

Evolution Paths

25G2G 3G

cdmaOneIS-95A

TDMA

cdmaOneIS-95B Cdma2000 1X

Cdma20001xEV-DV

Cdma20001xEV-DO

GSMGPRS

EDGE WCDMA

GSM Map Core Network

IS-41 Core Network

25G2G 3G

cdmaOneIS-95A

TDMA

cdmaOneIS-95B Cdma2000 1X

Cdma20001xEV-DV

Cdma20001xEV-DO

GSMGPRS

EDGE WCDMA

GSM Map Core Network

IS-41 Core Network

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 22

WCDMA

bull Spectrumndash 1920 MHz ndash 1980 MHz (uplink)ndash 2110 MHz ndash 2170 MHz (downlink)orndash 1850 MHz ndash 1910 MHz (uplink)ndash 1930 MHz ndash 1990 MHz (downlink)ndash Channel Spacing 5 Mhz

bull WCDMA is connected to the FDD Phy and the associated protocols Focus here

bull UTRAN-Universal Terrestrial Radio Access Network- is associated with the WCDMA radio Access Network

bull UMTS refers to the whole network

12 23

UMTS-FDD WCDMA

bull Wideband Direct Sequence Code Division Multiple Access

bull Does not assign a specific frequency to each user Instead every channel uses the full available spectrum

bull Individual conversations are encoded with a pseudo-random digital sequence

bull See httpwwwumtsworldcomtechnologyoverviewhtm

12 24

WCDMA Parameters

Channel BW 5 MHz

Forward RF Channel Structure Direct Spread

Chip Rate 384 Mcps

Frame Length 10 ms (38400 chips)

No of slotsframe 15

No of chipsslot 2560chips (Max 2560 bits)

Power Control Open and fast close loop (16 KHz)

Uplink Spreading Factor 4 to 256

Downlink Spreading Factor 4 to 512

12 25

Spreading Operation

bull Spreading means increasing the signal bandwidthbull Strictly speaking spreading includes two

operationsndash Channelisation (increases signal bandwidth) using

orthogonal codesndash Scrambling (does not affect the signal bandwidth) using

pseudo noise codes

12 26

Codes

Channellization Code Scrambling Code

Usage UL Separation of physical dataand control channels from same UEDL Separation of different userswithin one cell

UL Separation of terminalsDL Separation ofcellssectors

Length UL4-256 chipsDL4-512 chips

38400 chips

No of codes No of codes under one scrambling code= SF

UL Several millionDL 512

Code Family Orthogonal Variable Spreading Factor

Long 10ms code Gold codeShort code Extended S(2) code Family

Increase BW YES NO

12 27

UMTS Architecture

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

Cell site

Access Network

Core Network

User Equipment

12 28

UMTS Architecture

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 29

UMTS Architecture

bull User equipment-UEndash UMTS Subscriber Identity Module ndashUSIMndash Mobile Equipment- cell phone

bull UMTS Terrestrial Radio Access Networkndash Radio Network Subsystem

bull Node B- BSndash Transceiverndash Rate adaptationndash Radio resource managementndash Power control

12 30

UMTS Architecture

bull Radio Network Controller ndash RNCndash Radio access controlndash Connection controlndash Load congestion and admission controlndash Code allocation

ndash Core Networkbull MSCbull VLRbull HLRbull Gateway MSC ndash GMSC

ndash Supports circuit switched connectionsbull Serving GRPS Support Node ndash SGPRS

ndash Logical interface to UTRAN for packet transportraquo Session managementraquo Logical link management

bull Gateway GPRS Support Node ndash GGSNndash Supports packet switched transportndash This is an IP router

12 31

UMTS Protocol Architecture - User Plane

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

FP= Framing Protocol GTP-U= GPRS Tunneling Protocol-UserPDCP =Packet Data convergence Protocol

12 32

UMTS Protocol Stack

bull Radio Resource Control-RRC

bull Broadcastmulitcast control- BMC

bull Packet Data convergence Protocol- PDCPndash Header

compression

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

12 33

Packet SAR

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

12 34

Physical Layerbull The physical layer offers information transfer services to

the MAC layer These services are denoted as Transport channels (TrChrsquos) There are also Physical channels

bull Physical layer comprises following functionsndash 1048713 Various handover functionsndash 1048713 Error detection and report to higher layersndash 1048713 Multiplexing of transport channelsndash 1048713 Mapping of transport channels to physical channelsndash 1048713 Fast Close loop Power controlndash 1048713 Frequency and Time Synchronizationndash 1048713 Other responsibilities associated with transmitting and

receiving signals over the wireless mediandash Measurements

bull SIRbull Tx power Frame error rate etc

bull Physical channel is assigned a specific code

12 35

Transport amp Physical Channels

Transport Channel Physical Channel(ULDL) Dedicated Channel DCH Dedicated Physical Data Channel DPDCH

Dedicated Physical Control Channel DPCCH

(UL) Random Access Channel RACH Physical random access channel PRACH

(UL) Common packet channel CPCH Physical common packet channel PCPCH

(DL) Broadcast channel BCH Primary common control physical channel P-CCPCH

(DL) Forward access channel FACH(DL) Paging channel PCH

Secondary common control physical channel S-CCPCH

(DL) Downlink shared channel DSCH Physical downlink shared channel PDSCH

Signaling physical channels

Synchronization channel SCHCommon pilot channel CPICHAcquisition indication channel AICHPaging indication channel PICHCPCH Status indication channel CSICHCollision detectionChannel assignment indicator channel CDCA-ICH

12 36

UMTS FDD frame structure

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 37

MAC Layer

bull The MAC layer offers Data transfer to RLC and higher layers

bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically

bit rate within a predefined set per information unit delivered to the physical layer

ndash Service multiplexing on RACH FACH and dedicated channels

ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling

ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements

12 38

Physical Layer

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 39

RRC Layerbull The RRC layer offers the core network the following

servicesndash General control service which is used as an information

broadcast servicendash Notification service which is used for paging and

notification of a selected UEsndash Dedicated control service which is used for

establishmentrelease of a connection and transfer of messages using the connection

bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover

admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection

12 40

RLC Layer

bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is

appended to the information unit received from the higher layer

ndash Assured and un assured data transferbull The RLC layer comprises the following functions

ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the

WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the

control plane)ndash Duplicate detectionndash Flow controlndash Ciphering

12 41

RLC Layer-Modesbull Transparent-TM

ndash No header attachedndash SARndash SDU discard

bull Delete SDU if not sent before timer expiresndash Used for

bull Voicebull Some signaling

bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability

bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat

12 42

RLC Layer

From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the

UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

12 43

UE-Call states

bull Designed to ndash Take advantage of bursty nature of

datandash Save batter powerndash Maintains logical session and tracks

mobility but when appropriatendash releases dedicated resources to

increase overall capacityndash asleeps the UE

12 44

UE-Call states

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 45

UE-Call states

bull Idle modendash No active sessionndash UE monitors

Paging CHndash Sleeps between

paging cycles

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 46

UE-Call states

bull CELL_DCH state (Dedicated)ndash A dedicated physical

channel is allocated to the UE in uplink and downlink

ndash The UE is known on cell level according to its current active set

ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE

ndash Call typesbull Circuit Switched always in

this statebull Packet Switched in this

state if transferring large volume of data

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 47

UE-Call states

bull CELL_FACH state(Forward Access Ch)

ndash No dedicated physical channel is allocated to the UE

ndash The UE continuously monitors a FACH in the downlink

ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel

ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update

ndash Radio not put to sleepndash For packet switched sessions

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 48

UE-Call states

bull CELL_PCH state (Paging Ch)ndash No dedicated physical

channel is allocated to the UE

ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash Sleep between pagesndash A logical session is still upndash The position of the UE is

known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 49

UE-Call states

bull URA_PCH State ndash No dedicated channel is

allocated to the UEndash The UE selects a PCH with

the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state

ndash Similar to CELL_PCH state only the at the URA level

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 50

Power Control-PC

bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to

ensure that there is enough power for mobiles at the cell edge

bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control

commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command

ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break

12 51

Power Control

bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss

by means of a downlink beacon signalndash Provide a coarse initial power setting of

the mobile at the beginning of a connection

ndash Apply only prior to initiating the transmission on RACH or CPCH

12 52

Packet Access in WCDMA

bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection

bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared

bull RNC can decide when and how to send packets based on type of packet traffic

ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech

ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video

ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing

ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail

bull RNC can assign a packet to a specific channel

Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 53

Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the

downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft

handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts

bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts

bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink

orthogonal code is reserved according to maximum bit rate

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 54

Packet Access in WCDMA

bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner

bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer

bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate

bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and

bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 55

Packet Access in WCDMA

bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased

bull Advantagesndash resources are in full usage due to longer transmission

timendash small variation in interference levelndash longer uplink range due to lower bit rate

bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 56

Packet Access in WCDMA

bull Time division is normally used with shared channels and code division is normally used with dedicated channels

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 57

Packet Access in WCDMA

bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users

could be based on required transmission powerbull Users close to the BS requires less

transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate

bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput

bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 58

HSDPA amp Enhance Uplink

bull HSDPA = High Speed Downlink Packet Access

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 59

HSDPA amp Enhance Uplink

bull Remember it is better (more efficient) to have a large number of users sharing a single server

bull This lead to a desire to have fast allocation of shared resources

bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code

bull Uplink resourcesndash Interference at the BS

bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)

bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)

12 60

HSDPA amp Enhance Uplink

bull UTRAN Architecture with HSDPA and enhanced uplink

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 61

HSDPA amp Enhance Uplink

bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK

modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and

coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function

moved to Node-B (WCDMA packet scheduling was done in the RNC)

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 62

HSDPA amp Enhance Uplink

bull Gain in Performance

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 63

HSDPA

bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to

individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes

bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)

12 64

HSDPA

bull New frame structurendash Five subframesW-CDMA

framendash User data can be

assigned on a subframe basis

ndash System can adjust in 2ms

ndash Each subframe is a transmission time interval (TTI) = 2ms

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 65

HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared

resource is also in the time domain

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 66

HSDPA

bull Another view

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

Spreading Code

12 67

HSDPAbull Link Adaptation

ndash Remember the fast power control is commonly used to

bull Maintain constant EnergyNoise ratiobull Reduce effect of fading

ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant

EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 68

HSDPA

ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)

ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum

bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user

bull 1 ndash 2 Mbs closer to achievable under real conditions

12 69

HSDPA

bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE

bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms

bull CQI (0-30) each mapping into a modulation SF etc

bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression

bull

12 70

HSDPA

bull Schedulingndash The scheduler decides which user

should get access to each TTI ndash CQI provides input into a Scheduler

bull Proportional Fair (PF) Scheduler can be uses

bull Implementation Specific

12 71

HSDPA

bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number

of spreading codes limits rate not power so likely receive first transmission

ndash At greater distances move from BS see more errors IR will require additional transmission but not many

ndash HARQ only retransmit upon an ACK or NACK

12 72

HSDPA

From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007

12 73

HSDPA

bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2

ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent

Scheduling

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 8

Process

bull Mobile Call Initiationndash To make a call the

mobile keys the phone and hits send

ndash Phone transmitted over preselected control channel

ndash The BS relays information to the MSC

ndash MSC looking into the control message to get the and processes the call ie does the routing

12 9

Process

bull Call initiation to mobilendash Call routed to home MSCndash MSC checks HLR to

determine location of subscriber

ndash MSC has current visiting MSC stored in the HLR

ndash Home MSC communicates with the visiting MSC to rout the call

ndash The MSC sends a paging message to the paging message to BS

ndash The BS then send the paging message on to the subscriber on an assigned control (paging) channel

12 10

Process

bull Call acceptedndash MS sees the paging

signal and responds to the BS

ndash The BS send response to the MSC

ndash The MSC sets up the call to the BS

ndash The MSC also assigns a air interface channel for the BS to use for the call

ndash The MS communicates of the assigned channel

bull Here the call is between two mobiles

bull The communications is monitored for the ongoing call

12 11

Processbull Handoff (or handover)

ndash MS continually scans for control signals of BS

ndash Knowledge of the results of scans is used by MSC eg power of control signal drops below some threshold

ndash Upon that event the MSC will initiate a handoff procedure

ndash Handoff procedures can be implemented transparent to the users no interruption

ndash The handoff procedure tells the MS to use a specific channel to communicate with the new BS

12 12

Process

bull Handoffsndash Hard communications with old BS is terminated and

a new communications to a new BS is establishedndash Soft

bull Soft mobile station temporarily connected to more than one base station simultaneously

bull Softer mobile station temporarily connected to more than one sector of the same base station simultaneously

bull Soft-softer mobile station temporarily connected to more than one sector of the same base station and more than one base station simultaneously

bull Provides diversitybull Occurs at boundaries of sectorscells

12 13

Other Functions

bull Call blockingndash if all traffic channels busy

bull Call terminationndash when user hangs up

bull Call dropndash when BS cannot maintain required signal

strength

12 14

Other Functions Power control CDMA

bull Purposendash Removes near far effectndash Mitigates fadingndash Compensates changes in propagation conditionsndash In the system level

bull decrease interference from other usersbull increase capacity of the system

bull Uplinkndash Power control in uplink must make signal powers

from different users nearly equal in order to maximize the total capacity in the cell

bull Downlinkndash In downlink the power control must keep the signal

at minimal required level in order to decrease the interference to users in other cells

12 15

Other Functions Power control CDMA

bull Typesndash Open loop

bull set initial power for MSbull Each MS sets power based on individual

measurementsbull Coarse scale

ndash Closed loopbull BS knows receive power from each MSbull BS can tell each MS to set its power to achieve

system goalsbull Fast power control can mitigate fast fadingbull Three steps

ndash Transmissionndash Measurementndash Feedback

12 16

3G

bull 1G Analog Cellular Phones Needs a modem 96 kbps max

bull 2G Digital Cellular Phones No modem required 193 kbps max

bull 25G General Packet Radio Service (GPRS) 144kbps Data only

bull 3G Future high-speed data with Voice 64 kbps to 2 Mbpsndash W-CDMAUMTS (Universal Mobile

Telecommunications Systemndash CDMA2000

12 17

Organizations

ndash 3GPP 3rd Generation Partnership Project

ndash 3GPP is responsible for writing and maintaining the UMTS specifications

ndash hellip CDMA2000 hellipndash Internet Engineering Task Force (IETF)

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 18

3G- Advantages

3G phones promise - bull Improved digital voice communications bull Larger Bandwidth ndash Higher Data ratebull Greater subscriber capacity bull Fast packet-based data services like e-mail

short message service (SMS) and Internet access at broadband speeds

bull Most carriers also expect consumers to want - ndash location services ndash interactive gaming ndash streaming video ndash home monitoring and control ndash and who knows what else while being fully mobile

anywhere in the world

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 19

3G Capabilitiesbull Voice quality comparable to the public

switched telephone networkbull 144 Kbps- user in high-speed motor vehiclesbull 384 Kbps- pedestrians standing or moving

slowly over small areasbull Up to 2 Mbps- fixed applications like office usebull Symmetricalasymmetrical data transmission

ratesbull Support for both packet switched and circuit

switched data services like Internet Protocol (IP) traffic and real time video

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 20

Technologies

bull 3G is superior to the other digital standards like-ndash GSM (Global System for Mobile) communications standard

used worldwide ndash And IS-136 TDMA standard used primarily in North America ndash IS-95 CDMA systems

bull 3G Technologies-

ndash WCDMA or UMTS-FDD (Universal Mobile Telecommunications System - Frequency Division Duplex)---Direct Spread

ndash CDMA2000 - 1x-EvDOEvDV---Multi carrier

ndash UMTS ndash TDD (Time Division Duplex) or TD-SCDMA (Time Division - Synchronous Code Division Multiple Access) ---Time Code

ndash CDMA2000 and WCDMA or UMTS-FDD have similar architectures

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 21

Evolution Paths

25G2G 3G

cdmaOneIS-95A

TDMA

cdmaOneIS-95B Cdma2000 1X

Cdma20001xEV-DV

Cdma20001xEV-DO

GSMGPRS

EDGE WCDMA

GSM Map Core Network

IS-41 Core Network

25G2G 3G

cdmaOneIS-95A

TDMA

cdmaOneIS-95B Cdma2000 1X

Cdma20001xEV-DV

Cdma20001xEV-DO

GSMGPRS

EDGE WCDMA

GSM Map Core Network

IS-41 Core Network

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 22

WCDMA

bull Spectrumndash 1920 MHz ndash 1980 MHz (uplink)ndash 2110 MHz ndash 2170 MHz (downlink)orndash 1850 MHz ndash 1910 MHz (uplink)ndash 1930 MHz ndash 1990 MHz (downlink)ndash Channel Spacing 5 Mhz

bull WCDMA is connected to the FDD Phy and the associated protocols Focus here

bull UTRAN-Universal Terrestrial Radio Access Network- is associated with the WCDMA radio Access Network

bull UMTS refers to the whole network

12 23

UMTS-FDD WCDMA

bull Wideband Direct Sequence Code Division Multiple Access

bull Does not assign a specific frequency to each user Instead every channel uses the full available spectrum

bull Individual conversations are encoded with a pseudo-random digital sequence

bull See httpwwwumtsworldcomtechnologyoverviewhtm

12 24

WCDMA Parameters

Channel BW 5 MHz

Forward RF Channel Structure Direct Spread

Chip Rate 384 Mcps

Frame Length 10 ms (38400 chips)

No of slotsframe 15

No of chipsslot 2560chips (Max 2560 bits)

Power Control Open and fast close loop (16 KHz)

Uplink Spreading Factor 4 to 256

Downlink Spreading Factor 4 to 512

12 25

Spreading Operation

bull Spreading means increasing the signal bandwidthbull Strictly speaking spreading includes two

operationsndash Channelisation (increases signal bandwidth) using

orthogonal codesndash Scrambling (does not affect the signal bandwidth) using

pseudo noise codes

12 26

Codes

Channellization Code Scrambling Code

Usage UL Separation of physical dataand control channels from same UEDL Separation of different userswithin one cell

UL Separation of terminalsDL Separation ofcellssectors

Length UL4-256 chipsDL4-512 chips

38400 chips

No of codes No of codes under one scrambling code= SF

UL Several millionDL 512

Code Family Orthogonal Variable Spreading Factor

Long 10ms code Gold codeShort code Extended S(2) code Family

Increase BW YES NO

12 27

UMTS Architecture

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

Cell site

Access Network

Core Network

User Equipment

12 28

UMTS Architecture

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 29

UMTS Architecture

bull User equipment-UEndash UMTS Subscriber Identity Module ndashUSIMndash Mobile Equipment- cell phone

bull UMTS Terrestrial Radio Access Networkndash Radio Network Subsystem

bull Node B- BSndash Transceiverndash Rate adaptationndash Radio resource managementndash Power control

12 30

UMTS Architecture

bull Radio Network Controller ndash RNCndash Radio access controlndash Connection controlndash Load congestion and admission controlndash Code allocation

ndash Core Networkbull MSCbull VLRbull HLRbull Gateway MSC ndash GMSC

ndash Supports circuit switched connectionsbull Serving GRPS Support Node ndash SGPRS

ndash Logical interface to UTRAN for packet transportraquo Session managementraquo Logical link management

bull Gateway GPRS Support Node ndash GGSNndash Supports packet switched transportndash This is an IP router

12 31

UMTS Protocol Architecture - User Plane

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

FP= Framing Protocol GTP-U= GPRS Tunneling Protocol-UserPDCP =Packet Data convergence Protocol

12 32

UMTS Protocol Stack

bull Radio Resource Control-RRC

bull Broadcastmulitcast control- BMC

bull Packet Data convergence Protocol- PDCPndash Header

compression

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

12 33

Packet SAR

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

12 34

Physical Layerbull The physical layer offers information transfer services to

the MAC layer These services are denoted as Transport channels (TrChrsquos) There are also Physical channels

bull Physical layer comprises following functionsndash 1048713 Various handover functionsndash 1048713 Error detection and report to higher layersndash 1048713 Multiplexing of transport channelsndash 1048713 Mapping of transport channels to physical channelsndash 1048713 Fast Close loop Power controlndash 1048713 Frequency and Time Synchronizationndash 1048713 Other responsibilities associated with transmitting and

receiving signals over the wireless mediandash Measurements

bull SIRbull Tx power Frame error rate etc

bull Physical channel is assigned a specific code

12 35

Transport amp Physical Channels

Transport Channel Physical Channel(ULDL) Dedicated Channel DCH Dedicated Physical Data Channel DPDCH

Dedicated Physical Control Channel DPCCH

(UL) Random Access Channel RACH Physical random access channel PRACH

(UL) Common packet channel CPCH Physical common packet channel PCPCH

(DL) Broadcast channel BCH Primary common control physical channel P-CCPCH

(DL) Forward access channel FACH(DL) Paging channel PCH

Secondary common control physical channel S-CCPCH

(DL) Downlink shared channel DSCH Physical downlink shared channel PDSCH

Signaling physical channels

Synchronization channel SCHCommon pilot channel CPICHAcquisition indication channel AICHPaging indication channel PICHCPCH Status indication channel CSICHCollision detectionChannel assignment indicator channel CDCA-ICH

12 36

UMTS FDD frame structure

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 37

MAC Layer

bull The MAC layer offers Data transfer to RLC and higher layers

bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically

bit rate within a predefined set per information unit delivered to the physical layer

ndash Service multiplexing on RACH FACH and dedicated channels

ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling

ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements

12 38

Physical Layer

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 39

RRC Layerbull The RRC layer offers the core network the following

servicesndash General control service which is used as an information

broadcast servicendash Notification service which is used for paging and

notification of a selected UEsndash Dedicated control service which is used for

establishmentrelease of a connection and transfer of messages using the connection

bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover

admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection

12 40

RLC Layer

bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is

appended to the information unit received from the higher layer

ndash Assured and un assured data transferbull The RLC layer comprises the following functions

ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the

WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the

control plane)ndash Duplicate detectionndash Flow controlndash Ciphering

12 41

RLC Layer-Modesbull Transparent-TM

ndash No header attachedndash SARndash SDU discard

bull Delete SDU if not sent before timer expiresndash Used for

bull Voicebull Some signaling

bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability

bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat

12 42

RLC Layer

From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the

UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

12 43

UE-Call states

bull Designed to ndash Take advantage of bursty nature of

datandash Save batter powerndash Maintains logical session and tracks

mobility but when appropriatendash releases dedicated resources to

increase overall capacityndash asleeps the UE

12 44

UE-Call states

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 45

UE-Call states

bull Idle modendash No active sessionndash UE monitors

Paging CHndash Sleeps between

paging cycles

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 46

UE-Call states

bull CELL_DCH state (Dedicated)ndash A dedicated physical

channel is allocated to the UE in uplink and downlink

ndash The UE is known on cell level according to its current active set

ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE

ndash Call typesbull Circuit Switched always in

this statebull Packet Switched in this

state if transferring large volume of data

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 47

UE-Call states

bull CELL_FACH state(Forward Access Ch)

ndash No dedicated physical channel is allocated to the UE

ndash The UE continuously monitors a FACH in the downlink

ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel

ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update

ndash Radio not put to sleepndash For packet switched sessions

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 48

UE-Call states

bull CELL_PCH state (Paging Ch)ndash No dedicated physical

channel is allocated to the UE

ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash Sleep between pagesndash A logical session is still upndash The position of the UE is

known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 49

UE-Call states

bull URA_PCH State ndash No dedicated channel is

allocated to the UEndash The UE selects a PCH with

the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state

ndash Similar to CELL_PCH state only the at the URA level

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 50

Power Control-PC

bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to

ensure that there is enough power for mobiles at the cell edge

bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control

commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command

ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break

12 51

Power Control

bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss

by means of a downlink beacon signalndash Provide a coarse initial power setting of

the mobile at the beginning of a connection

ndash Apply only prior to initiating the transmission on RACH or CPCH

12 52

Packet Access in WCDMA

bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection

bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared

bull RNC can decide when and how to send packets based on type of packet traffic

ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech

ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video

ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing

ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail

bull RNC can assign a packet to a specific channel

Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 53

Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the

downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft

handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts

bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts

bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink

orthogonal code is reserved according to maximum bit rate

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 54

Packet Access in WCDMA

bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner

bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer

bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate

bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and

bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 55

Packet Access in WCDMA

bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased

bull Advantagesndash resources are in full usage due to longer transmission

timendash small variation in interference levelndash longer uplink range due to lower bit rate

bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 56

Packet Access in WCDMA

bull Time division is normally used with shared channels and code division is normally used with dedicated channels

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 57

Packet Access in WCDMA

bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users

could be based on required transmission powerbull Users close to the BS requires less

transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate

bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput

bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 58

HSDPA amp Enhance Uplink

bull HSDPA = High Speed Downlink Packet Access

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 59

HSDPA amp Enhance Uplink

bull Remember it is better (more efficient) to have a large number of users sharing a single server

bull This lead to a desire to have fast allocation of shared resources

bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code

bull Uplink resourcesndash Interference at the BS

bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)

bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)

12 60

HSDPA amp Enhance Uplink

bull UTRAN Architecture with HSDPA and enhanced uplink

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 61

HSDPA amp Enhance Uplink

bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK

modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and

coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function

moved to Node-B (WCDMA packet scheduling was done in the RNC)

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 62

HSDPA amp Enhance Uplink

bull Gain in Performance

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 63

HSDPA

bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to

individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes

bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)

12 64

HSDPA

bull New frame structurendash Five subframesW-CDMA

framendash User data can be

assigned on a subframe basis

ndash System can adjust in 2ms

ndash Each subframe is a transmission time interval (TTI) = 2ms

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 65

HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared

resource is also in the time domain

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 66

HSDPA

bull Another view

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

Spreading Code

12 67

HSDPAbull Link Adaptation

ndash Remember the fast power control is commonly used to

bull Maintain constant EnergyNoise ratiobull Reduce effect of fading

ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant

EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 68

HSDPA

ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)

ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum

bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user

bull 1 ndash 2 Mbs closer to achievable under real conditions

12 69

HSDPA

bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE

bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms

bull CQI (0-30) each mapping into a modulation SF etc

bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression

bull

12 70

HSDPA

bull Schedulingndash The scheduler decides which user

should get access to each TTI ndash CQI provides input into a Scheduler

bull Proportional Fair (PF) Scheduler can be uses

bull Implementation Specific

12 71

HSDPA

bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number

of spreading codes limits rate not power so likely receive first transmission

ndash At greater distances move from BS see more errors IR will require additional transmission but not many

ndash HARQ only retransmit upon an ACK or NACK

12 72

HSDPA

From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007

12 73

HSDPA

bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2

ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent

Scheduling

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 9

Process

bull Call initiation to mobilendash Call routed to home MSCndash MSC checks HLR to

determine location of subscriber

ndash MSC has current visiting MSC stored in the HLR

ndash Home MSC communicates with the visiting MSC to rout the call

ndash The MSC sends a paging message to the paging message to BS

ndash The BS then send the paging message on to the subscriber on an assigned control (paging) channel

12 10

Process

bull Call acceptedndash MS sees the paging

signal and responds to the BS

ndash The BS send response to the MSC

ndash The MSC sets up the call to the BS

ndash The MSC also assigns a air interface channel for the BS to use for the call

ndash The MS communicates of the assigned channel

bull Here the call is between two mobiles

bull The communications is monitored for the ongoing call

12 11

Processbull Handoff (or handover)

ndash MS continually scans for control signals of BS

ndash Knowledge of the results of scans is used by MSC eg power of control signal drops below some threshold

ndash Upon that event the MSC will initiate a handoff procedure

ndash Handoff procedures can be implemented transparent to the users no interruption

ndash The handoff procedure tells the MS to use a specific channel to communicate with the new BS

12 12

Process

bull Handoffsndash Hard communications with old BS is terminated and

a new communications to a new BS is establishedndash Soft

bull Soft mobile station temporarily connected to more than one base station simultaneously

bull Softer mobile station temporarily connected to more than one sector of the same base station simultaneously

bull Soft-softer mobile station temporarily connected to more than one sector of the same base station and more than one base station simultaneously

bull Provides diversitybull Occurs at boundaries of sectorscells

12 13

Other Functions

bull Call blockingndash if all traffic channels busy

bull Call terminationndash when user hangs up

bull Call dropndash when BS cannot maintain required signal

strength

12 14

Other Functions Power control CDMA

bull Purposendash Removes near far effectndash Mitigates fadingndash Compensates changes in propagation conditionsndash In the system level

bull decrease interference from other usersbull increase capacity of the system

bull Uplinkndash Power control in uplink must make signal powers

from different users nearly equal in order to maximize the total capacity in the cell

bull Downlinkndash In downlink the power control must keep the signal

at minimal required level in order to decrease the interference to users in other cells

12 15

Other Functions Power control CDMA

bull Typesndash Open loop

bull set initial power for MSbull Each MS sets power based on individual

measurementsbull Coarse scale

ndash Closed loopbull BS knows receive power from each MSbull BS can tell each MS to set its power to achieve

system goalsbull Fast power control can mitigate fast fadingbull Three steps

ndash Transmissionndash Measurementndash Feedback

12 16

3G

bull 1G Analog Cellular Phones Needs a modem 96 kbps max

bull 2G Digital Cellular Phones No modem required 193 kbps max

bull 25G General Packet Radio Service (GPRS) 144kbps Data only

bull 3G Future high-speed data with Voice 64 kbps to 2 Mbpsndash W-CDMAUMTS (Universal Mobile

Telecommunications Systemndash CDMA2000

12 17

Organizations

ndash 3GPP 3rd Generation Partnership Project

ndash 3GPP is responsible for writing and maintaining the UMTS specifications

ndash hellip CDMA2000 hellipndash Internet Engineering Task Force (IETF)

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 18

3G- Advantages

3G phones promise - bull Improved digital voice communications bull Larger Bandwidth ndash Higher Data ratebull Greater subscriber capacity bull Fast packet-based data services like e-mail

short message service (SMS) and Internet access at broadband speeds

bull Most carriers also expect consumers to want - ndash location services ndash interactive gaming ndash streaming video ndash home monitoring and control ndash and who knows what else while being fully mobile

anywhere in the world

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 19

3G Capabilitiesbull Voice quality comparable to the public

switched telephone networkbull 144 Kbps- user in high-speed motor vehiclesbull 384 Kbps- pedestrians standing or moving

slowly over small areasbull Up to 2 Mbps- fixed applications like office usebull Symmetricalasymmetrical data transmission

ratesbull Support for both packet switched and circuit

switched data services like Internet Protocol (IP) traffic and real time video

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 20

Technologies

bull 3G is superior to the other digital standards like-ndash GSM (Global System for Mobile) communications standard

used worldwide ndash And IS-136 TDMA standard used primarily in North America ndash IS-95 CDMA systems

bull 3G Technologies-

ndash WCDMA or UMTS-FDD (Universal Mobile Telecommunications System - Frequency Division Duplex)---Direct Spread

ndash CDMA2000 - 1x-EvDOEvDV---Multi carrier

ndash UMTS ndash TDD (Time Division Duplex) or TD-SCDMA (Time Division - Synchronous Code Division Multiple Access) ---Time Code

ndash CDMA2000 and WCDMA or UMTS-FDD have similar architectures

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 21

Evolution Paths

25G2G 3G

cdmaOneIS-95A

TDMA

cdmaOneIS-95B Cdma2000 1X

Cdma20001xEV-DV

Cdma20001xEV-DO

GSMGPRS

EDGE WCDMA

GSM Map Core Network

IS-41 Core Network

25G2G 3G

cdmaOneIS-95A

TDMA

cdmaOneIS-95B Cdma2000 1X

Cdma20001xEV-DV

Cdma20001xEV-DO

GSMGPRS

EDGE WCDMA

GSM Map Core Network

IS-41 Core Network

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 22

WCDMA

bull Spectrumndash 1920 MHz ndash 1980 MHz (uplink)ndash 2110 MHz ndash 2170 MHz (downlink)orndash 1850 MHz ndash 1910 MHz (uplink)ndash 1930 MHz ndash 1990 MHz (downlink)ndash Channel Spacing 5 Mhz

bull WCDMA is connected to the FDD Phy and the associated protocols Focus here

bull UTRAN-Universal Terrestrial Radio Access Network- is associated with the WCDMA radio Access Network

bull UMTS refers to the whole network

12 23

UMTS-FDD WCDMA

bull Wideband Direct Sequence Code Division Multiple Access

bull Does not assign a specific frequency to each user Instead every channel uses the full available spectrum

bull Individual conversations are encoded with a pseudo-random digital sequence

bull See httpwwwumtsworldcomtechnologyoverviewhtm

12 24

WCDMA Parameters

Channel BW 5 MHz

Forward RF Channel Structure Direct Spread

Chip Rate 384 Mcps

Frame Length 10 ms (38400 chips)

No of slotsframe 15

No of chipsslot 2560chips (Max 2560 bits)

Power Control Open and fast close loop (16 KHz)

Uplink Spreading Factor 4 to 256

Downlink Spreading Factor 4 to 512

12 25

Spreading Operation

bull Spreading means increasing the signal bandwidthbull Strictly speaking spreading includes two

operationsndash Channelisation (increases signal bandwidth) using

orthogonal codesndash Scrambling (does not affect the signal bandwidth) using

pseudo noise codes

12 26

Codes

Channellization Code Scrambling Code

Usage UL Separation of physical dataand control channels from same UEDL Separation of different userswithin one cell

UL Separation of terminalsDL Separation ofcellssectors

Length UL4-256 chipsDL4-512 chips

38400 chips

No of codes No of codes under one scrambling code= SF

UL Several millionDL 512

Code Family Orthogonal Variable Spreading Factor

Long 10ms code Gold codeShort code Extended S(2) code Family

Increase BW YES NO

12 27

UMTS Architecture

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

Cell site

Access Network

Core Network

User Equipment

12 28

UMTS Architecture

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 29

UMTS Architecture

bull User equipment-UEndash UMTS Subscriber Identity Module ndashUSIMndash Mobile Equipment- cell phone

bull UMTS Terrestrial Radio Access Networkndash Radio Network Subsystem

bull Node B- BSndash Transceiverndash Rate adaptationndash Radio resource managementndash Power control

12 30

UMTS Architecture

bull Radio Network Controller ndash RNCndash Radio access controlndash Connection controlndash Load congestion and admission controlndash Code allocation

ndash Core Networkbull MSCbull VLRbull HLRbull Gateway MSC ndash GMSC

ndash Supports circuit switched connectionsbull Serving GRPS Support Node ndash SGPRS

ndash Logical interface to UTRAN for packet transportraquo Session managementraquo Logical link management

bull Gateway GPRS Support Node ndash GGSNndash Supports packet switched transportndash This is an IP router

12 31

UMTS Protocol Architecture - User Plane

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

FP= Framing Protocol GTP-U= GPRS Tunneling Protocol-UserPDCP =Packet Data convergence Protocol

12 32

UMTS Protocol Stack

bull Radio Resource Control-RRC

bull Broadcastmulitcast control- BMC

bull Packet Data convergence Protocol- PDCPndash Header

compression

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

12 33

Packet SAR

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

12 34

Physical Layerbull The physical layer offers information transfer services to

the MAC layer These services are denoted as Transport channels (TrChrsquos) There are also Physical channels

bull Physical layer comprises following functionsndash 1048713 Various handover functionsndash 1048713 Error detection and report to higher layersndash 1048713 Multiplexing of transport channelsndash 1048713 Mapping of transport channels to physical channelsndash 1048713 Fast Close loop Power controlndash 1048713 Frequency and Time Synchronizationndash 1048713 Other responsibilities associated with transmitting and

receiving signals over the wireless mediandash Measurements

bull SIRbull Tx power Frame error rate etc

bull Physical channel is assigned a specific code

12 35

Transport amp Physical Channels

Transport Channel Physical Channel(ULDL) Dedicated Channel DCH Dedicated Physical Data Channel DPDCH

Dedicated Physical Control Channel DPCCH

(UL) Random Access Channel RACH Physical random access channel PRACH

(UL) Common packet channel CPCH Physical common packet channel PCPCH

(DL) Broadcast channel BCH Primary common control physical channel P-CCPCH

(DL) Forward access channel FACH(DL) Paging channel PCH

Secondary common control physical channel S-CCPCH

(DL) Downlink shared channel DSCH Physical downlink shared channel PDSCH

Signaling physical channels

Synchronization channel SCHCommon pilot channel CPICHAcquisition indication channel AICHPaging indication channel PICHCPCH Status indication channel CSICHCollision detectionChannel assignment indicator channel CDCA-ICH

12 36

UMTS FDD frame structure

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 37

MAC Layer

bull The MAC layer offers Data transfer to RLC and higher layers

bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically

bit rate within a predefined set per information unit delivered to the physical layer

ndash Service multiplexing on RACH FACH and dedicated channels

ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling

ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements

12 38

Physical Layer

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 39

RRC Layerbull The RRC layer offers the core network the following

servicesndash General control service which is used as an information

broadcast servicendash Notification service which is used for paging and

notification of a selected UEsndash Dedicated control service which is used for

establishmentrelease of a connection and transfer of messages using the connection

bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover

admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection

12 40

RLC Layer

bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is

appended to the information unit received from the higher layer

ndash Assured and un assured data transferbull The RLC layer comprises the following functions

ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the

WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the

control plane)ndash Duplicate detectionndash Flow controlndash Ciphering

12 41

RLC Layer-Modesbull Transparent-TM

ndash No header attachedndash SARndash SDU discard

bull Delete SDU if not sent before timer expiresndash Used for

bull Voicebull Some signaling

bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability

bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat

12 42

RLC Layer

From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the

UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

12 43

UE-Call states

bull Designed to ndash Take advantage of bursty nature of

datandash Save batter powerndash Maintains logical session and tracks

mobility but when appropriatendash releases dedicated resources to

increase overall capacityndash asleeps the UE

12 44

UE-Call states

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 45

UE-Call states

bull Idle modendash No active sessionndash UE monitors

Paging CHndash Sleeps between

paging cycles

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 46

UE-Call states

bull CELL_DCH state (Dedicated)ndash A dedicated physical

channel is allocated to the UE in uplink and downlink

ndash The UE is known on cell level according to its current active set

ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE

ndash Call typesbull Circuit Switched always in

this statebull Packet Switched in this

state if transferring large volume of data

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 47

UE-Call states

bull CELL_FACH state(Forward Access Ch)

ndash No dedicated physical channel is allocated to the UE

ndash The UE continuously monitors a FACH in the downlink

ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel

ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update

ndash Radio not put to sleepndash For packet switched sessions

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 48

UE-Call states

bull CELL_PCH state (Paging Ch)ndash No dedicated physical

channel is allocated to the UE

ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash Sleep between pagesndash A logical session is still upndash The position of the UE is

known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 49

UE-Call states

bull URA_PCH State ndash No dedicated channel is

allocated to the UEndash The UE selects a PCH with

the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state

ndash Similar to CELL_PCH state only the at the URA level

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 50

Power Control-PC

bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to

ensure that there is enough power for mobiles at the cell edge

bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control

commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command

ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break

12 51

Power Control

bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss

by means of a downlink beacon signalndash Provide a coarse initial power setting of

the mobile at the beginning of a connection

ndash Apply only prior to initiating the transmission on RACH or CPCH

12 52

Packet Access in WCDMA

bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection

bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared

bull RNC can decide when and how to send packets based on type of packet traffic

ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech

ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video

ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing

ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail

bull RNC can assign a packet to a specific channel

Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 53

Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the

downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft

handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts

bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts

bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink

orthogonal code is reserved according to maximum bit rate

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 54

Packet Access in WCDMA

bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner

bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer

bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate

bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and

bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 55

Packet Access in WCDMA

bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased

bull Advantagesndash resources are in full usage due to longer transmission

timendash small variation in interference levelndash longer uplink range due to lower bit rate

bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 56

Packet Access in WCDMA

bull Time division is normally used with shared channels and code division is normally used with dedicated channels

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 57

Packet Access in WCDMA

bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users

could be based on required transmission powerbull Users close to the BS requires less

transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate

bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput

bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 58

HSDPA amp Enhance Uplink

bull HSDPA = High Speed Downlink Packet Access

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 59

HSDPA amp Enhance Uplink

bull Remember it is better (more efficient) to have a large number of users sharing a single server

bull This lead to a desire to have fast allocation of shared resources

bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code

bull Uplink resourcesndash Interference at the BS

bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)

bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)

12 60

HSDPA amp Enhance Uplink

bull UTRAN Architecture with HSDPA and enhanced uplink

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 61

HSDPA amp Enhance Uplink

bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK

modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and

coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function

moved to Node-B (WCDMA packet scheduling was done in the RNC)

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 62

HSDPA amp Enhance Uplink

bull Gain in Performance

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 63

HSDPA

bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to

individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes

bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)

12 64

HSDPA

bull New frame structurendash Five subframesW-CDMA

framendash User data can be

assigned on a subframe basis

ndash System can adjust in 2ms

ndash Each subframe is a transmission time interval (TTI) = 2ms

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 65

HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared

resource is also in the time domain

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 66

HSDPA

bull Another view

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

Spreading Code

12 67

HSDPAbull Link Adaptation

ndash Remember the fast power control is commonly used to

bull Maintain constant EnergyNoise ratiobull Reduce effect of fading

ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant

EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 68

HSDPA

ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)

ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum

bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user

bull 1 ndash 2 Mbs closer to achievable under real conditions

12 69

HSDPA

bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE

bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms

bull CQI (0-30) each mapping into a modulation SF etc

bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression

bull

12 70

HSDPA

bull Schedulingndash The scheduler decides which user

should get access to each TTI ndash CQI provides input into a Scheduler

bull Proportional Fair (PF) Scheduler can be uses

bull Implementation Specific

12 71

HSDPA

bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number

of spreading codes limits rate not power so likely receive first transmission

ndash At greater distances move from BS see more errors IR will require additional transmission but not many

ndash HARQ only retransmit upon an ACK or NACK

12 72

HSDPA

From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007

12 73

HSDPA

bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2

ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent

Scheduling

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 10

Process

bull Call acceptedndash MS sees the paging

signal and responds to the BS

ndash The BS send response to the MSC

ndash The MSC sets up the call to the BS

ndash The MSC also assigns a air interface channel for the BS to use for the call

ndash The MS communicates of the assigned channel

bull Here the call is between two mobiles

bull The communications is monitored for the ongoing call

12 11

Processbull Handoff (or handover)

ndash MS continually scans for control signals of BS

ndash Knowledge of the results of scans is used by MSC eg power of control signal drops below some threshold

ndash Upon that event the MSC will initiate a handoff procedure

ndash Handoff procedures can be implemented transparent to the users no interruption

ndash The handoff procedure tells the MS to use a specific channel to communicate with the new BS

12 12

Process

bull Handoffsndash Hard communications with old BS is terminated and

a new communications to a new BS is establishedndash Soft

bull Soft mobile station temporarily connected to more than one base station simultaneously

bull Softer mobile station temporarily connected to more than one sector of the same base station simultaneously

bull Soft-softer mobile station temporarily connected to more than one sector of the same base station and more than one base station simultaneously

bull Provides diversitybull Occurs at boundaries of sectorscells

12 13

Other Functions

bull Call blockingndash if all traffic channels busy

bull Call terminationndash when user hangs up

bull Call dropndash when BS cannot maintain required signal

strength

12 14

Other Functions Power control CDMA

bull Purposendash Removes near far effectndash Mitigates fadingndash Compensates changes in propagation conditionsndash In the system level

bull decrease interference from other usersbull increase capacity of the system

bull Uplinkndash Power control in uplink must make signal powers

from different users nearly equal in order to maximize the total capacity in the cell

bull Downlinkndash In downlink the power control must keep the signal

at minimal required level in order to decrease the interference to users in other cells

12 15

Other Functions Power control CDMA

bull Typesndash Open loop

bull set initial power for MSbull Each MS sets power based on individual

measurementsbull Coarse scale

ndash Closed loopbull BS knows receive power from each MSbull BS can tell each MS to set its power to achieve

system goalsbull Fast power control can mitigate fast fadingbull Three steps

ndash Transmissionndash Measurementndash Feedback

12 16

3G

bull 1G Analog Cellular Phones Needs a modem 96 kbps max

bull 2G Digital Cellular Phones No modem required 193 kbps max

bull 25G General Packet Radio Service (GPRS) 144kbps Data only

bull 3G Future high-speed data with Voice 64 kbps to 2 Mbpsndash W-CDMAUMTS (Universal Mobile

Telecommunications Systemndash CDMA2000

12 17

Organizations

ndash 3GPP 3rd Generation Partnership Project

ndash 3GPP is responsible for writing and maintaining the UMTS specifications

ndash hellip CDMA2000 hellipndash Internet Engineering Task Force (IETF)

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 18

3G- Advantages

3G phones promise - bull Improved digital voice communications bull Larger Bandwidth ndash Higher Data ratebull Greater subscriber capacity bull Fast packet-based data services like e-mail

short message service (SMS) and Internet access at broadband speeds

bull Most carriers also expect consumers to want - ndash location services ndash interactive gaming ndash streaming video ndash home monitoring and control ndash and who knows what else while being fully mobile

anywhere in the world

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 19

3G Capabilitiesbull Voice quality comparable to the public

switched telephone networkbull 144 Kbps- user in high-speed motor vehiclesbull 384 Kbps- pedestrians standing or moving

slowly over small areasbull Up to 2 Mbps- fixed applications like office usebull Symmetricalasymmetrical data transmission

ratesbull Support for both packet switched and circuit

switched data services like Internet Protocol (IP) traffic and real time video

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 20

Technologies

bull 3G is superior to the other digital standards like-ndash GSM (Global System for Mobile) communications standard

used worldwide ndash And IS-136 TDMA standard used primarily in North America ndash IS-95 CDMA systems

bull 3G Technologies-

ndash WCDMA or UMTS-FDD (Universal Mobile Telecommunications System - Frequency Division Duplex)---Direct Spread

ndash CDMA2000 - 1x-EvDOEvDV---Multi carrier

ndash UMTS ndash TDD (Time Division Duplex) or TD-SCDMA (Time Division - Synchronous Code Division Multiple Access) ---Time Code

ndash CDMA2000 and WCDMA or UMTS-FDD have similar architectures

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 21

Evolution Paths

25G2G 3G

cdmaOneIS-95A

TDMA

cdmaOneIS-95B Cdma2000 1X

Cdma20001xEV-DV

Cdma20001xEV-DO

GSMGPRS

EDGE WCDMA

GSM Map Core Network

IS-41 Core Network

25G2G 3G

cdmaOneIS-95A

TDMA

cdmaOneIS-95B Cdma2000 1X

Cdma20001xEV-DV

Cdma20001xEV-DO

GSMGPRS

EDGE WCDMA

GSM Map Core Network

IS-41 Core Network

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 22

WCDMA

bull Spectrumndash 1920 MHz ndash 1980 MHz (uplink)ndash 2110 MHz ndash 2170 MHz (downlink)orndash 1850 MHz ndash 1910 MHz (uplink)ndash 1930 MHz ndash 1990 MHz (downlink)ndash Channel Spacing 5 Mhz

bull WCDMA is connected to the FDD Phy and the associated protocols Focus here

bull UTRAN-Universal Terrestrial Radio Access Network- is associated with the WCDMA radio Access Network

bull UMTS refers to the whole network

12 23

UMTS-FDD WCDMA

bull Wideband Direct Sequence Code Division Multiple Access

bull Does not assign a specific frequency to each user Instead every channel uses the full available spectrum

bull Individual conversations are encoded with a pseudo-random digital sequence

bull See httpwwwumtsworldcomtechnologyoverviewhtm

12 24

WCDMA Parameters

Channel BW 5 MHz

Forward RF Channel Structure Direct Spread

Chip Rate 384 Mcps

Frame Length 10 ms (38400 chips)

No of slotsframe 15

No of chipsslot 2560chips (Max 2560 bits)

Power Control Open and fast close loop (16 KHz)

Uplink Spreading Factor 4 to 256

Downlink Spreading Factor 4 to 512

12 25

Spreading Operation

bull Spreading means increasing the signal bandwidthbull Strictly speaking spreading includes two

operationsndash Channelisation (increases signal bandwidth) using

orthogonal codesndash Scrambling (does not affect the signal bandwidth) using

pseudo noise codes

12 26

Codes

Channellization Code Scrambling Code

Usage UL Separation of physical dataand control channels from same UEDL Separation of different userswithin one cell

UL Separation of terminalsDL Separation ofcellssectors

Length UL4-256 chipsDL4-512 chips

38400 chips

No of codes No of codes under one scrambling code= SF

UL Several millionDL 512

Code Family Orthogonal Variable Spreading Factor

Long 10ms code Gold codeShort code Extended S(2) code Family

Increase BW YES NO

12 27

UMTS Architecture

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

Cell site

Access Network

Core Network

User Equipment

12 28

UMTS Architecture

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 29

UMTS Architecture

bull User equipment-UEndash UMTS Subscriber Identity Module ndashUSIMndash Mobile Equipment- cell phone

bull UMTS Terrestrial Radio Access Networkndash Radio Network Subsystem

bull Node B- BSndash Transceiverndash Rate adaptationndash Radio resource managementndash Power control

12 30

UMTS Architecture

bull Radio Network Controller ndash RNCndash Radio access controlndash Connection controlndash Load congestion and admission controlndash Code allocation

ndash Core Networkbull MSCbull VLRbull HLRbull Gateway MSC ndash GMSC

ndash Supports circuit switched connectionsbull Serving GRPS Support Node ndash SGPRS

ndash Logical interface to UTRAN for packet transportraquo Session managementraquo Logical link management

bull Gateway GPRS Support Node ndash GGSNndash Supports packet switched transportndash This is an IP router

12 31

UMTS Protocol Architecture - User Plane

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

FP= Framing Protocol GTP-U= GPRS Tunneling Protocol-UserPDCP =Packet Data convergence Protocol

12 32

UMTS Protocol Stack

bull Radio Resource Control-RRC

bull Broadcastmulitcast control- BMC

bull Packet Data convergence Protocol- PDCPndash Header

compression

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

12 33

Packet SAR

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

12 34

Physical Layerbull The physical layer offers information transfer services to

the MAC layer These services are denoted as Transport channels (TrChrsquos) There are also Physical channels

bull Physical layer comprises following functionsndash 1048713 Various handover functionsndash 1048713 Error detection and report to higher layersndash 1048713 Multiplexing of transport channelsndash 1048713 Mapping of transport channels to physical channelsndash 1048713 Fast Close loop Power controlndash 1048713 Frequency and Time Synchronizationndash 1048713 Other responsibilities associated with transmitting and

receiving signals over the wireless mediandash Measurements

bull SIRbull Tx power Frame error rate etc

bull Physical channel is assigned a specific code

12 35

Transport amp Physical Channels

Transport Channel Physical Channel(ULDL) Dedicated Channel DCH Dedicated Physical Data Channel DPDCH

Dedicated Physical Control Channel DPCCH

(UL) Random Access Channel RACH Physical random access channel PRACH

(UL) Common packet channel CPCH Physical common packet channel PCPCH

(DL) Broadcast channel BCH Primary common control physical channel P-CCPCH

(DL) Forward access channel FACH(DL) Paging channel PCH

Secondary common control physical channel S-CCPCH

(DL) Downlink shared channel DSCH Physical downlink shared channel PDSCH

Signaling physical channels

Synchronization channel SCHCommon pilot channel CPICHAcquisition indication channel AICHPaging indication channel PICHCPCH Status indication channel CSICHCollision detectionChannel assignment indicator channel CDCA-ICH

12 36

UMTS FDD frame structure

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 37

MAC Layer

bull The MAC layer offers Data transfer to RLC and higher layers

bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically

bit rate within a predefined set per information unit delivered to the physical layer

ndash Service multiplexing on RACH FACH and dedicated channels

ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling

ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements

12 38

Physical Layer

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 39

RRC Layerbull The RRC layer offers the core network the following

servicesndash General control service which is used as an information

broadcast servicendash Notification service which is used for paging and

notification of a selected UEsndash Dedicated control service which is used for

establishmentrelease of a connection and transfer of messages using the connection

bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover

admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection

12 40

RLC Layer

bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is

appended to the information unit received from the higher layer

ndash Assured and un assured data transferbull The RLC layer comprises the following functions

ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the

WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the

control plane)ndash Duplicate detectionndash Flow controlndash Ciphering

12 41

RLC Layer-Modesbull Transparent-TM

ndash No header attachedndash SARndash SDU discard

bull Delete SDU if not sent before timer expiresndash Used for

bull Voicebull Some signaling

bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability

bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat

12 42

RLC Layer

From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the

UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

12 43

UE-Call states

bull Designed to ndash Take advantage of bursty nature of

datandash Save batter powerndash Maintains logical session and tracks

mobility but when appropriatendash releases dedicated resources to

increase overall capacityndash asleeps the UE

12 44

UE-Call states

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 45

UE-Call states

bull Idle modendash No active sessionndash UE monitors

Paging CHndash Sleeps between

paging cycles

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 46

UE-Call states

bull CELL_DCH state (Dedicated)ndash A dedicated physical

channel is allocated to the UE in uplink and downlink

ndash The UE is known on cell level according to its current active set

ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE

ndash Call typesbull Circuit Switched always in

this statebull Packet Switched in this

state if transferring large volume of data

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 47

UE-Call states

bull CELL_FACH state(Forward Access Ch)

ndash No dedicated physical channel is allocated to the UE

ndash The UE continuously monitors a FACH in the downlink

ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel

ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update

ndash Radio not put to sleepndash For packet switched sessions

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 48

UE-Call states

bull CELL_PCH state (Paging Ch)ndash No dedicated physical

channel is allocated to the UE

ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash Sleep between pagesndash A logical session is still upndash The position of the UE is

known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 49

UE-Call states

bull URA_PCH State ndash No dedicated channel is

allocated to the UEndash The UE selects a PCH with

the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state

ndash Similar to CELL_PCH state only the at the URA level

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 50

Power Control-PC

bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to

ensure that there is enough power for mobiles at the cell edge

bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control

commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command

ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break

12 51

Power Control

bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss

by means of a downlink beacon signalndash Provide a coarse initial power setting of

the mobile at the beginning of a connection

ndash Apply only prior to initiating the transmission on RACH or CPCH

12 52

Packet Access in WCDMA

bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection

bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared

bull RNC can decide when and how to send packets based on type of packet traffic

ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech

ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video

ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing

ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail

bull RNC can assign a packet to a specific channel

Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 53

Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the

downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft

handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts

bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts

bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink

orthogonal code is reserved according to maximum bit rate

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 54

Packet Access in WCDMA

bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner

bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer

bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate

bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and

bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 55

Packet Access in WCDMA

bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased

bull Advantagesndash resources are in full usage due to longer transmission

timendash small variation in interference levelndash longer uplink range due to lower bit rate

bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 56

Packet Access in WCDMA

bull Time division is normally used with shared channels and code division is normally used with dedicated channels

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 57

Packet Access in WCDMA

bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users

could be based on required transmission powerbull Users close to the BS requires less

transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate

bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput

bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 58

HSDPA amp Enhance Uplink

bull HSDPA = High Speed Downlink Packet Access

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 59

HSDPA amp Enhance Uplink

bull Remember it is better (more efficient) to have a large number of users sharing a single server

bull This lead to a desire to have fast allocation of shared resources

bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code

bull Uplink resourcesndash Interference at the BS

bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)

bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)

12 60

HSDPA amp Enhance Uplink

bull UTRAN Architecture with HSDPA and enhanced uplink

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 61

HSDPA amp Enhance Uplink

bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK

modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and

coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function

moved to Node-B (WCDMA packet scheduling was done in the RNC)

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 62

HSDPA amp Enhance Uplink

bull Gain in Performance

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 63

HSDPA

bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to

individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes

bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)

12 64

HSDPA

bull New frame structurendash Five subframesW-CDMA

framendash User data can be

assigned on a subframe basis

ndash System can adjust in 2ms

ndash Each subframe is a transmission time interval (TTI) = 2ms

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 65

HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared

resource is also in the time domain

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 66

HSDPA

bull Another view

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

Spreading Code

12 67

HSDPAbull Link Adaptation

ndash Remember the fast power control is commonly used to

bull Maintain constant EnergyNoise ratiobull Reduce effect of fading

ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant

EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 68

HSDPA

ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)

ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum

bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user

bull 1 ndash 2 Mbs closer to achievable under real conditions

12 69

HSDPA

bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE

bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms

bull CQI (0-30) each mapping into a modulation SF etc

bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression

bull

12 70

HSDPA

bull Schedulingndash The scheduler decides which user

should get access to each TTI ndash CQI provides input into a Scheduler

bull Proportional Fair (PF) Scheduler can be uses

bull Implementation Specific

12 71

HSDPA

bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number

of spreading codes limits rate not power so likely receive first transmission

ndash At greater distances move from BS see more errors IR will require additional transmission but not many

ndash HARQ only retransmit upon an ACK or NACK

12 72

HSDPA

From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007

12 73

HSDPA

bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2

ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent

Scheduling

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 11

Processbull Handoff (or handover)

ndash MS continually scans for control signals of BS

ndash Knowledge of the results of scans is used by MSC eg power of control signal drops below some threshold

ndash Upon that event the MSC will initiate a handoff procedure

ndash Handoff procedures can be implemented transparent to the users no interruption

ndash The handoff procedure tells the MS to use a specific channel to communicate with the new BS

12 12

Process

bull Handoffsndash Hard communications with old BS is terminated and

a new communications to a new BS is establishedndash Soft

bull Soft mobile station temporarily connected to more than one base station simultaneously

bull Softer mobile station temporarily connected to more than one sector of the same base station simultaneously

bull Soft-softer mobile station temporarily connected to more than one sector of the same base station and more than one base station simultaneously

bull Provides diversitybull Occurs at boundaries of sectorscells

12 13

Other Functions

bull Call blockingndash if all traffic channels busy

bull Call terminationndash when user hangs up

bull Call dropndash when BS cannot maintain required signal

strength

12 14

Other Functions Power control CDMA

bull Purposendash Removes near far effectndash Mitigates fadingndash Compensates changes in propagation conditionsndash In the system level

bull decrease interference from other usersbull increase capacity of the system

bull Uplinkndash Power control in uplink must make signal powers

from different users nearly equal in order to maximize the total capacity in the cell

bull Downlinkndash In downlink the power control must keep the signal

at minimal required level in order to decrease the interference to users in other cells

12 15

Other Functions Power control CDMA

bull Typesndash Open loop

bull set initial power for MSbull Each MS sets power based on individual

measurementsbull Coarse scale

ndash Closed loopbull BS knows receive power from each MSbull BS can tell each MS to set its power to achieve

system goalsbull Fast power control can mitigate fast fadingbull Three steps

ndash Transmissionndash Measurementndash Feedback

12 16

3G

bull 1G Analog Cellular Phones Needs a modem 96 kbps max

bull 2G Digital Cellular Phones No modem required 193 kbps max

bull 25G General Packet Radio Service (GPRS) 144kbps Data only

bull 3G Future high-speed data with Voice 64 kbps to 2 Mbpsndash W-CDMAUMTS (Universal Mobile

Telecommunications Systemndash CDMA2000

12 17

Organizations

ndash 3GPP 3rd Generation Partnership Project

ndash 3GPP is responsible for writing and maintaining the UMTS specifications

ndash hellip CDMA2000 hellipndash Internet Engineering Task Force (IETF)

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 18

3G- Advantages

3G phones promise - bull Improved digital voice communications bull Larger Bandwidth ndash Higher Data ratebull Greater subscriber capacity bull Fast packet-based data services like e-mail

short message service (SMS) and Internet access at broadband speeds

bull Most carriers also expect consumers to want - ndash location services ndash interactive gaming ndash streaming video ndash home monitoring and control ndash and who knows what else while being fully mobile

anywhere in the world

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 19

3G Capabilitiesbull Voice quality comparable to the public

switched telephone networkbull 144 Kbps- user in high-speed motor vehiclesbull 384 Kbps- pedestrians standing or moving

slowly over small areasbull Up to 2 Mbps- fixed applications like office usebull Symmetricalasymmetrical data transmission

ratesbull Support for both packet switched and circuit

switched data services like Internet Protocol (IP) traffic and real time video

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 20

Technologies

bull 3G is superior to the other digital standards like-ndash GSM (Global System for Mobile) communications standard

used worldwide ndash And IS-136 TDMA standard used primarily in North America ndash IS-95 CDMA systems

bull 3G Technologies-

ndash WCDMA or UMTS-FDD (Universal Mobile Telecommunications System - Frequency Division Duplex)---Direct Spread

ndash CDMA2000 - 1x-EvDOEvDV---Multi carrier

ndash UMTS ndash TDD (Time Division Duplex) or TD-SCDMA (Time Division - Synchronous Code Division Multiple Access) ---Time Code

ndash CDMA2000 and WCDMA or UMTS-FDD have similar architectures

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 21

Evolution Paths

25G2G 3G

cdmaOneIS-95A

TDMA

cdmaOneIS-95B Cdma2000 1X

Cdma20001xEV-DV

Cdma20001xEV-DO

GSMGPRS

EDGE WCDMA

GSM Map Core Network

IS-41 Core Network

25G2G 3G

cdmaOneIS-95A

TDMA

cdmaOneIS-95B Cdma2000 1X

Cdma20001xEV-DV

Cdma20001xEV-DO

GSMGPRS

EDGE WCDMA

GSM Map Core Network

IS-41 Core Network

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 22

WCDMA

bull Spectrumndash 1920 MHz ndash 1980 MHz (uplink)ndash 2110 MHz ndash 2170 MHz (downlink)orndash 1850 MHz ndash 1910 MHz (uplink)ndash 1930 MHz ndash 1990 MHz (downlink)ndash Channel Spacing 5 Mhz

bull WCDMA is connected to the FDD Phy and the associated protocols Focus here

bull UTRAN-Universal Terrestrial Radio Access Network- is associated with the WCDMA radio Access Network

bull UMTS refers to the whole network

12 23

UMTS-FDD WCDMA

bull Wideband Direct Sequence Code Division Multiple Access

bull Does not assign a specific frequency to each user Instead every channel uses the full available spectrum

bull Individual conversations are encoded with a pseudo-random digital sequence

bull See httpwwwumtsworldcomtechnologyoverviewhtm

12 24

WCDMA Parameters

Channel BW 5 MHz

Forward RF Channel Structure Direct Spread

Chip Rate 384 Mcps

Frame Length 10 ms (38400 chips)

No of slotsframe 15

No of chipsslot 2560chips (Max 2560 bits)

Power Control Open and fast close loop (16 KHz)

Uplink Spreading Factor 4 to 256

Downlink Spreading Factor 4 to 512

12 25

Spreading Operation

bull Spreading means increasing the signal bandwidthbull Strictly speaking spreading includes two

operationsndash Channelisation (increases signal bandwidth) using

orthogonal codesndash Scrambling (does not affect the signal bandwidth) using

pseudo noise codes

12 26

Codes

Channellization Code Scrambling Code

Usage UL Separation of physical dataand control channels from same UEDL Separation of different userswithin one cell

UL Separation of terminalsDL Separation ofcellssectors

Length UL4-256 chipsDL4-512 chips

38400 chips

No of codes No of codes under one scrambling code= SF

UL Several millionDL 512

Code Family Orthogonal Variable Spreading Factor

Long 10ms code Gold codeShort code Extended S(2) code Family

Increase BW YES NO

12 27

UMTS Architecture

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

Cell site

Access Network

Core Network

User Equipment

12 28

UMTS Architecture

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 29

UMTS Architecture

bull User equipment-UEndash UMTS Subscriber Identity Module ndashUSIMndash Mobile Equipment- cell phone

bull UMTS Terrestrial Radio Access Networkndash Radio Network Subsystem

bull Node B- BSndash Transceiverndash Rate adaptationndash Radio resource managementndash Power control

12 30

UMTS Architecture

bull Radio Network Controller ndash RNCndash Radio access controlndash Connection controlndash Load congestion and admission controlndash Code allocation

ndash Core Networkbull MSCbull VLRbull HLRbull Gateway MSC ndash GMSC

ndash Supports circuit switched connectionsbull Serving GRPS Support Node ndash SGPRS

ndash Logical interface to UTRAN for packet transportraquo Session managementraquo Logical link management

bull Gateway GPRS Support Node ndash GGSNndash Supports packet switched transportndash This is an IP router

12 31

UMTS Protocol Architecture - User Plane

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

FP= Framing Protocol GTP-U= GPRS Tunneling Protocol-UserPDCP =Packet Data convergence Protocol

12 32

UMTS Protocol Stack

bull Radio Resource Control-RRC

bull Broadcastmulitcast control- BMC

bull Packet Data convergence Protocol- PDCPndash Header

compression

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

12 33

Packet SAR

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

12 34

Physical Layerbull The physical layer offers information transfer services to

the MAC layer These services are denoted as Transport channels (TrChrsquos) There are also Physical channels

bull Physical layer comprises following functionsndash 1048713 Various handover functionsndash 1048713 Error detection and report to higher layersndash 1048713 Multiplexing of transport channelsndash 1048713 Mapping of transport channels to physical channelsndash 1048713 Fast Close loop Power controlndash 1048713 Frequency and Time Synchronizationndash 1048713 Other responsibilities associated with transmitting and

receiving signals over the wireless mediandash Measurements

bull SIRbull Tx power Frame error rate etc

bull Physical channel is assigned a specific code

12 35

Transport amp Physical Channels

Transport Channel Physical Channel(ULDL) Dedicated Channel DCH Dedicated Physical Data Channel DPDCH

Dedicated Physical Control Channel DPCCH

(UL) Random Access Channel RACH Physical random access channel PRACH

(UL) Common packet channel CPCH Physical common packet channel PCPCH

(DL) Broadcast channel BCH Primary common control physical channel P-CCPCH

(DL) Forward access channel FACH(DL) Paging channel PCH

Secondary common control physical channel S-CCPCH

(DL) Downlink shared channel DSCH Physical downlink shared channel PDSCH

Signaling physical channels

Synchronization channel SCHCommon pilot channel CPICHAcquisition indication channel AICHPaging indication channel PICHCPCH Status indication channel CSICHCollision detectionChannel assignment indicator channel CDCA-ICH

12 36

UMTS FDD frame structure

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 37

MAC Layer

bull The MAC layer offers Data transfer to RLC and higher layers

bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically

bit rate within a predefined set per information unit delivered to the physical layer

ndash Service multiplexing on RACH FACH and dedicated channels

ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling

ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements

12 38

Physical Layer

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 39

RRC Layerbull The RRC layer offers the core network the following

servicesndash General control service which is used as an information

broadcast servicendash Notification service which is used for paging and

notification of a selected UEsndash Dedicated control service which is used for

establishmentrelease of a connection and transfer of messages using the connection

bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover

admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection

12 40

RLC Layer

bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is

appended to the information unit received from the higher layer

ndash Assured and un assured data transferbull The RLC layer comprises the following functions

ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the

WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the

control plane)ndash Duplicate detectionndash Flow controlndash Ciphering

12 41

RLC Layer-Modesbull Transparent-TM

ndash No header attachedndash SARndash SDU discard

bull Delete SDU if not sent before timer expiresndash Used for

bull Voicebull Some signaling

bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability

bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat

12 42

RLC Layer

From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the

UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

12 43

UE-Call states

bull Designed to ndash Take advantage of bursty nature of

datandash Save batter powerndash Maintains logical session and tracks

mobility but when appropriatendash releases dedicated resources to

increase overall capacityndash asleeps the UE

12 44

UE-Call states

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 45

UE-Call states

bull Idle modendash No active sessionndash UE monitors

Paging CHndash Sleeps between

paging cycles

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 46

UE-Call states

bull CELL_DCH state (Dedicated)ndash A dedicated physical

channel is allocated to the UE in uplink and downlink

ndash The UE is known on cell level according to its current active set

ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE

ndash Call typesbull Circuit Switched always in

this statebull Packet Switched in this

state if transferring large volume of data

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 47

UE-Call states

bull CELL_FACH state(Forward Access Ch)

ndash No dedicated physical channel is allocated to the UE

ndash The UE continuously monitors a FACH in the downlink

ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel

ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update

ndash Radio not put to sleepndash For packet switched sessions

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 48

UE-Call states

bull CELL_PCH state (Paging Ch)ndash No dedicated physical

channel is allocated to the UE

ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash Sleep between pagesndash A logical session is still upndash The position of the UE is

known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 49

UE-Call states

bull URA_PCH State ndash No dedicated channel is

allocated to the UEndash The UE selects a PCH with

the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state

ndash Similar to CELL_PCH state only the at the URA level

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 50

Power Control-PC

bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to

ensure that there is enough power for mobiles at the cell edge

bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control

commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command

ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break

12 51

Power Control

bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss

by means of a downlink beacon signalndash Provide a coarse initial power setting of

the mobile at the beginning of a connection

ndash Apply only prior to initiating the transmission on RACH or CPCH

12 52

Packet Access in WCDMA

bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection

bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared

bull RNC can decide when and how to send packets based on type of packet traffic

ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech

ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video

ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing

ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail

bull RNC can assign a packet to a specific channel

Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 53

Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the

downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft

handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts

bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts

bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink

orthogonal code is reserved according to maximum bit rate

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 54

Packet Access in WCDMA

bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner

bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer

bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate

bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and

bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 55

Packet Access in WCDMA

bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased

bull Advantagesndash resources are in full usage due to longer transmission

timendash small variation in interference levelndash longer uplink range due to lower bit rate

bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 56

Packet Access in WCDMA

bull Time division is normally used with shared channels and code division is normally used with dedicated channels

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 57

Packet Access in WCDMA

bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users

could be based on required transmission powerbull Users close to the BS requires less

transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate

bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput

bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 58

HSDPA amp Enhance Uplink

bull HSDPA = High Speed Downlink Packet Access

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 59

HSDPA amp Enhance Uplink

bull Remember it is better (more efficient) to have a large number of users sharing a single server

bull This lead to a desire to have fast allocation of shared resources

bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code

bull Uplink resourcesndash Interference at the BS

bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)

bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)

12 60

HSDPA amp Enhance Uplink

bull UTRAN Architecture with HSDPA and enhanced uplink

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 61

HSDPA amp Enhance Uplink

bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK

modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and

coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function

moved to Node-B (WCDMA packet scheduling was done in the RNC)

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 62

HSDPA amp Enhance Uplink

bull Gain in Performance

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 63

HSDPA

bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to

individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes

bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)

12 64

HSDPA

bull New frame structurendash Five subframesW-CDMA

framendash User data can be

assigned on a subframe basis

ndash System can adjust in 2ms

ndash Each subframe is a transmission time interval (TTI) = 2ms

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 65

HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared

resource is also in the time domain

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 66

HSDPA

bull Another view

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

Spreading Code

12 67

HSDPAbull Link Adaptation

ndash Remember the fast power control is commonly used to

bull Maintain constant EnergyNoise ratiobull Reduce effect of fading

ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant

EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 68

HSDPA

ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)

ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum

bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user

bull 1 ndash 2 Mbs closer to achievable under real conditions

12 69

HSDPA

bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE

bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms

bull CQI (0-30) each mapping into a modulation SF etc

bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression

bull

12 70

HSDPA

bull Schedulingndash The scheduler decides which user

should get access to each TTI ndash CQI provides input into a Scheduler

bull Proportional Fair (PF) Scheduler can be uses

bull Implementation Specific

12 71

HSDPA

bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number

of spreading codes limits rate not power so likely receive first transmission

ndash At greater distances move from BS see more errors IR will require additional transmission but not many

ndash HARQ only retransmit upon an ACK or NACK

12 72

HSDPA

From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007

12 73

HSDPA

bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2

ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent

Scheduling

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 12

Process

bull Handoffsndash Hard communications with old BS is terminated and

a new communications to a new BS is establishedndash Soft

bull Soft mobile station temporarily connected to more than one base station simultaneously

bull Softer mobile station temporarily connected to more than one sector of the same base station simultaneously

bull Soft-softer mobile station temporarily connected to more than one sector of the same base station and more than one base station simultaneously

bull Provides diversitybull Occurs at boundaries of sectorscells

12 13

Other Functions

bull Call blockingndash if all traffic channels busy

bull Call terminationndash when user hangs up

bull Call dropndash when BS cannot maintain required signal

strength

12 14

Other Functions Power control CDMA

bull Purposendash Removes near far effectndash Mitigates fadingndash Compensates changes in propagation conditionsndash In the system level

bull decrease interference from other usersbull increase capacity of the system

bull Uplinkndash Power control in uplink must make signal powers

from different users nearly equal in order to maximize the total capacity in the cell

bull Downlinkndash In downlink the power control must keep the signal

at minimal required level in order to decrease the interference to users in other cells

12 15

Other Functions Power control CDMA

bull Typesndash Open loop

bull set initial power for MSbull Each MS sets power based on individual

measurementsbull Coarse scale

ndash Closed loopbull BS knows receive power from each MSbull BS can tell each MS to set its power to achieve

system goalsbull Fast power control can mitigate fast fadingbull Three steps

ndash Transmissionndash Measurementndash Feedback

12 16

3G

bull 1G Analog Cellular Phones Needs a modem 96 kbps max

bull 2G Digital Cellular Phones No modem required 193 kbps max

bull 25G General Packet Radio Service (GPRS) 144kbps Data only

bull 3G Future high-speed data with Voice 64 kbps to 2 Mbpsndash W-CDMAUMTS (Universal Mobile

Telecommunications Systemndash CDMA2000

12 17

Organizations

ndash 3GPP 3rd Generation Partnership Project

ndash 3GPP is responsible for writing and maintaining the UMTS specifications

ndash hellip CDMA2000 hellipndash Internet Engineering Task Force (IETF)

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 18

3G- Advantages

3G phones promise - bull Improved digital voice communications bull Larger Bandwidth ndash Higher Data ratebull Greater subscriber capacity bull Fast packet-based data services like e-mail

short message service (SMS) and Internet access at broadband speeds

bull Most carriers also expect consumers to want - ndash location services ndash interactive gaming ndash streaming video ndash home monitoring and control ndash and who knows what else while being fully mobile

anywhere in the world

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 19

3G Capabilitiesbull Voice quality comparable to the public

switched telephone networkbull 144 Kbps- user in high-speed motor vehiclesbull 384 Kbps- pedestrians standing or moving

slowly over small areasbull Up to 2 Mbps- fixed applications like office usebull Symmetricalasymmetrical data transmission

ratesbull Support for both packet switched and circuit

switched data services like Internet Protocol (IP) traffic and real time video

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 20

Technologies

bull 3G is superior to the other digital standards like-ndash GSM (Global System for Mobile) communications standard

used worldwide ndash And IS-136 TDMA standard used primarily in North America ndash IS-95 CDMA systems

bull 3G Technologies-

ndash WCDMA or UMTS-FDD (Universal Mobile Telecommunications System - Frequency Division Duplex)---Direct Spread

ndash CDMA2000 - 1x-EvDOEvDV---Multi carrier

ndash UMTS ndash TDD (Time Division Duplex) or TD-SCDMA (Time Division - Synchronous Code Division Multiple Access) ---Time Code

ndash CDMA2000 and WCDMA or UMTS-FDD have similar architectures

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 21

Evolution Paths

25G2G 3G

cdmaOneIS-95A

TDMA

cdmaOneIS-95B Cdma2000 1X

Cdma20001xEV-DV

Cdma20001xEV-DO

GSMGPRS

EDGE WCDMA

GSM Map Core Network

IS-41 Core Network

25G2G 3G

cdmaOneIS-95A

TDMA

cdmaOneIS-95B Cdma2000 1X

Cdma20001xEV-DV

Cdma20001xEV-DO

GSMGPRS

EDGE WCDMA

GSM Map Core Network

IS-41 Core Network

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 22

WCDMA

bull Spectrumndash 1920 MHz ndash 1980 MHz (uplink)ndash 2110 MHz ndash 2170 MHz (downlink)orndash 1850 MHz ndash 1910 MHz (uplink)ndash 1930 MHz ndash 1990 MHz (downlink)ndash Channel Spacing 5 Mhz

bull WCDMA is connected to the FDD Phy and the associated protocols Focus here

bull UTRAN-Universal Terrestrial Radio Access Network- is associated with the WCDMA radio Access Network

bull UMTS refers to the whole network

12 23

UMTS-FDD WCDMA

bull Wideband Direct Sequence Code Division Multiple Access

bull Does not assign a specific frequency to each user Instead every channel uses the full available spectrum

bull Individual conversations are encoded with a pseudo-random digital sequence

bull See httpwwwumtsworldcomtechnologyoverviewhtm

12 24

WCDMA Parameters

Channel BW 5 MHz

Forward RF Channel Structure Direct Spread

Chip Rate 384 Mcps

Frame Length 10 ms (38400 chips)

No of slotsframe 15

No of chipsslot 2560chips (Max 2560 bits)

Power Control Open and fast close loop (16 KHz)

Uplink Spreading Factor 4 to 256

Downlink Spreading Factor 4 to 512

12 25

Spreading Operation

bull Spreading means increasing the signal bandwidthbull Strictly speaking spreading includes two

operationsndash Channelisation (increases signal bandwidth) using

orthogonal codesndash Scrambling (does not affect the signal bandwidth) using

pseudo noise codes

12 26

Codes

Channellization Code Scrambling Code

Usage UL Separation of physical dataand control channels from same UEDL Separation of different userswithin one cell

UL Separation of terminalsDL Separation ofcellssectors

Length UL4-256 chipsDL4-512 chips

38400 chips

No of codes No of codes under one scrambling code= SF

UL Several millionDL 512

Code Family Orthogonal Variable Spreading Factor

Long 10ms code Gold codeShort code Extended S(2) code Family

Increase BW YES NO

12 27

UMTS Architecture

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

Cell site

Access Network

Core Network

User Equipment

12 28

UMTS Architecture

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 29

UMTS Architecture

bull User equipment-UEndash UMTS Subscriber Identity Module ndashUSIMndash Mobile Equipment- cell phone

bull UMTS Terrestrial Radio Access Networkndash Radio Network Subsystem

bull Node B- BSndash Transceiverndash Rate adaptationndash Radio resource managementndash Power control

12 30

UMTS Architecture

bull Radio Network Controller ndash RNCndash Radio access controlndash Connection controlndash Load congestion and admission controlndash Code allocation

ndash Core Networkbull MSCbull VLRbull HLRbull Gateway MSC ndash GMSC

ndash Supports circuit switched connectionsbull Serving GRPS Support Node ndash SGPRS

ndash Logical interface to UTRAN for packet transportraquo Session managementraquo Logical link management

bull Gateway GPRS Support Node ndash GGSNndash Supports packet switched transportndash This is an IP router

12 31

UMTS Protocol Architecture - User Plane

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

FP= Framing Protocol GTP-U= GPRS Tunneling Protocol-UserPDCP =Packet Data convergence Protocol

12 32

UMTS Protocol Stack

bull Radio Resource Control-RRC

bull Broadcastmulitcast control- BMC

bull Packet Data convergence Protocol- PDCPndash Header

compression

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

12 33

Packet SAR

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

12 34

Physical Layerbull The physical layer offers information transfer services to

the MAC layer These services are denoted as Transport channels (TrChrsquos) There are also Physical channels

bull Physical layer comprises following functionsndash 1048713 Various handover functionsndash 1048713 Error detection and report to higher layersndash 1048713 Multiplexing of transport channelsndash 1048713 Mapping of transport channels to physical channelsndash 1048713 Fast Close loop Power controlndash 1048713 Frequency and Time Synchronizationndash 1048713 Other responsibilities associated with transmitting and

receiving signals over the wireless mediandash Measurements

bull SIRbull Tx power Frame error rate etc

bull Physical channel is assigned a specific code

12 35

Transport amp Physical Channels

Transport Channel Physical Channel(ULDL) Dedicated Channel DCH Dedicated Physical Data Channel DPDCH

Dedicated Physical Control Channel DPCCH

(UL) Random Access Channel RACH Physical random access channel PRACH

(UL) Common packet channel CPCH Physical common packet channel PCPCH

(DL) Broadcast channel BCH Primary common control physical channel P-CCPCH

(DL) Forward access channel FACH(DL) Paging channel PCH

Secondary common control physical channel S-CCPCH

(DL) Downlink shared channel DSCH Physical downlink shared channel PDSCH

Signaling physical channels

Synchronization channel SCHCommon pilot channel CPICHAcquisition indication channel AICHPaging indication channel PICHCPCH Status indication channel CSICHCollision detectionChannel assignment indicator channel CDCA-ICH

12 36

UMTS FDD frame structure

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 37

MAC Layer

bull The MAC layer offers Data transfer to RLC and higher layers

bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically

bit rate within a predefined set per information unit delivered to the physical layer

ndash Service multiplexing on RACH FACH and dedicated channels

ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling

ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements

12 38

Physical Layer

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 39

RRC Layerbull The RRC layer offers the core network the following

servicesndash General control service which is used as an information

broadcast servicendash Notification service which is used for paging and

notification of a selected UEsndash Dedicated control service which is used for

establishmentrelease of a connection and transfer of messages using the connection

bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover

admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection

12 40

RLC Layer

bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is

appended to the information unit received from the higher layer

ndash Assured and un assured data transferbull The RLC layer comprises the following functions

ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the

WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the

control plane)ndash Duplicate detectionndash Flow controlndash Ciphering

12 41

RLC Layer-Modesbull Transparent-TM

ndash No header attachedndash SARndash SDU discard

bull Delete SDU if not sent before timer expiresndash Used for

bull Voicebull Some signaling

bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability

bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat

12 42

RLC Layer

From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the

UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

12 43

UE-Call states

bull Designed to ndash Take advantage of bursty nature of

datandash Save batter powerndash Maintains logical session and tracks

mobility but when appropriatendash releases dedicated resources to

increase overall capacityndash asleeps the UE

12 44

UE-Call states

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 45

UE-Call states

bull Idle modendash No active sessionndash UE monitors

Paging CHndash Sleeps between

paging cycles

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 46

UE-Call states

bull CELL_DCH state (Dedicated)ndash A dedicated physical

channel is allocated to the UE in uplink and downlink

ndash The UE is known on cell level according to its current active set

ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE

ndash Call typesbull Circuit Switched always in

this statebull Packet Switched in this

state if transferring large volume of data

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 47

UE-Call states

bull CELL_FACH state(Forward Access Ch)

ndash No dedicated physical channel is allocated to the UE

ndash The UE continuously monitors a FACH in the downlink

ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel

ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update

ndash Radio not put to sleepndash For packet switched sessions

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 48

UE-Call states

bull CELL_PCH state (Paging Ch)ndash No dedicated physical

channel is allocated to the UE

ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash Sleep between pagesndash A logical session is still upndash The position of the UE is

known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 49

UE-Call states

bull URA_PCH State ndash No dedicated channel is

allocated to the UEndash The UE selects a PCH with

the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state

ndash Similar to CELL_PCH state only the at the URA level

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 50

Power Control-PC

bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to

ensure that there is enough power for mobiles at the cell edge

bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control

commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command

ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break

12 51

Power Control

bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss

by means of a downlink beacon signalndash Provide a coarse initial power setting of

the mobile at the beginning of a connection

ndash Apply only prior to initiating the transmission on RACH or CPCH

12 52

Packet Access in WCDMA

bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection

bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared

bull RNC can decide when and how to send packets based on type of packet traffic

ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech

ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video

ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing

ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail

bull RNC can assign a packet to a specific channel

Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 53

Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the

downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft

handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts

bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts

bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink

orthogonal code is reserved according to maximum bit rate

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 54

Packet Access in WCDMA

bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner

bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer

bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate

bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and

bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 55

Packet Access in WCDMA

bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased

bull Advantagesndash resources are in full usage due to longer transmission

timendash small variation in interference levelndash longer uplink range due to lower bit rate

bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 56

Packet Access in WCDMA

bull Time division is normally used with shared channels and code division is normally used with dedicated channels

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 57

Packet Access in WCDMA

bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users

could be based on required transmission powerbull Users close to the BS requires less

transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate

bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput

bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 58

HSDPA amp Enhance Uplink

bull HSDPA = High Speed Downlink Packet Access

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 59

HSDPA amp Enhance Uplink

bull Remember it is better (more efficient) to have a large number of users sharing a single server

bull This lead to a desire to have fast allocation of shared resources

bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code

bull Uplink resourcesndash Interference at the BS

bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)

bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)

12 60

HSDPA amp Enhance Uplink

bull UTRAN Architecture with HSDPA and enhanced uplink

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 61

HSDPA amp Enhance Uplink

bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK

modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and

coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function

moved to Node-B (WCDMA packet scheduling was done in the RNC)

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 62

HSDPA amp Enhance Uplink

bull Gain in Performance

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 63

HSDPA

bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to

individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes

bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)

12 64

HSDPA

bull New frame structurendash Five subframesW-CDMA

framendash User data can be

assigned on a subframe basis

ndash System can adjust in 2ms

ndash Each subframe is a transmission time interval (TTI) = 2ms

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 65

HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared

resource is also in the time domain

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 66

HSDPA

bull Another view

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

Spreading Code

12 67

HSDPAbull Link Adaptation

ndash Remember the fast power control is commonly used to

bull Maintain constant EnergyNoise ratiobull Reduce effect of fading

ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant

EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 68

HSDPA

ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)

ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum

bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user

bull 1 ndash 2 Mbs closer to achievable under real conditions

12 69

HSDPA

bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE

bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms

bull CQI (0-30) each mapping into a modulation SF etc

bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression

bull

12 70

HSDPA

bull Schedulingndash The scheduler decides which user

should get access to each TTI ndash CQI provides input into a Scheduler

bull Proportional Fair (PF) Scheduler can be uses

bull Implementation Specific

12 71

HSDPA

bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number

of spreading codes limits rate not power so likely receive first transmission

ndash At greater distances move from BS see more errors IR will require additional transmission but not many

ndash HARQ only retransmit upon an ACK or NACK

12 72

HSDPA

From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007

12 73

HSDPA

bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2

ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent

Scheduling

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 13

Other Functions

bull Call blockingndash if all traffic channels busy

bull Call terminationndash when user hangs up

bull Call dropndash when BS cannot maintain required signal

strength

12 14

Other Functions Power control CDMA

bull Purposendash Removes near far effectndash Mitigates fadingndash Compensates changes in propagation conditionsndash In the system level

bull decrease interference from other usersbull increase capacity of the system

bull Uplinkndash Power control in uplink must make signal powers

from different users nearly equal in order to maximize the total capacity in the cell

bull Downlinkndash In downlink the power control must keep the signal

at minimal required level in order to decrease the interference to users in other cells

12 15

Other Functions Power control CDMA

bull Typesndash Open loop

bull set initial power for MSbull Each MS sets power based on individual

measurementsbull Coarse scale

ndash Closed loopbull BS knows receive power from each MSbull BS can tell each MS to set its power to achieve

system goalsbull Fast power control can mitigate fast fadingbull Three steps

ndash Transmissionndash Measurementndash Feedback

12 16

3G

bull 1G Analog Cellular Phones Needs a modem 96 kbps max

bull 2G Digital Cellular Phones No modem required 193 kbps max

bull 25G General Packet Radio Service (GPRS) 144kbps Data only

bull 3G Future high-speed data with Voice 64 kbps to 2 Mbpsndash W-CDMAUMTS (Universal Mobile

Telecommunications Systemndash CDMA2000

12 17

Organizations

ndash 3GPP 3rd Generation Partnership Project

ndash 3GPP is responsible for writing and maintaining the UMTS specifications

ndash hellip CDMA2000 hellipndash Internet Engineering Task Force (IETF)

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 18

3G- Advantages

3G phones promise - bull Improved digital voice communications bull Larger Bandwidth ndash Higher Data ratebull Greater subscriber capacity bull Fast packet-based data services like e-mail

short message service (SMS) and Internet access at broadband speeds

bull Most carriers also expect consumers to want - ndash location services ndash interactive gaming ndash streaming video ndash home monitoring and control ndash and who knows what else while being fully mobile

anywhere in the world

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 19

3G Capabilitiesbull Voice quality comparable to the public

switched telephone networkbull 144 Kbps- user in high-speed motor vehiclesbull 384 Kbps- pedestrians standing or moving

slowly over small areasbull Up to 2 Mbps- fixed applications like office usebull Symmetricalasymmetrical data transmission

ratesbull Support for both packet switched and circuit

switched data services like Internet Protocol (IP) traffic and real time video

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 20

Technologies

bull 3G is superior to the other digital standards like-ndash GSM (Global System for Mobile) communications standard

used worldwide ndash And IS-136 TDMA standard used primarily in North America ndash IS-95 CDMA systems

bull 3G Technologies-

ndash WCDMA or UMTS-FDD (Universal Mobile Telecommunications System - Frequency Division Duplex)---Direct Spread

ndash CDMA2000 - 1x-EvDOEvDV---Multi carrier

ndash UMTS ndash TDD (Time Division Duplex) or TD-SCDMA (Time Division - Synchronous Code Division Multiple Access) ---Time Code

ndash CDMA2000 and WCDMA or UMTS-FDD have similar architectures

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 21

Evolution Paths

25G2G 3G

cdmaOneIS-95A

TDMA

cdmaOneIS-95B Cdma2000 1X

Cdma20001xEV-DV

Cdma20001xEV-DO

GSMGPRS

EDGE WCDMA

GSM Map Core Network

IS-41 Core Network

25G2G 3G

cdmaOneIS-95A

TDMA

cdmaOneIS-95B Cdma2000 1X

Cdma20001xEV-DV

Cdma20001xEV-DO

GSMGPRS

EDGE WCDMA

GSM Map Core Network

IS-41 Core Network

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 22

WCDMA

bull Spectrumndash 1920 MHz ndash 1980 MHz (uplink)ndash 2110 MHz ndash 2170 MHz (downlink)orndash 1850 MHz ndash 1910 MHz (uplink)ndash 1930 MHz ndash 1990 MHz (downlink)ndash Channel Spacing 5 Mhz

bull WCDMA is connected to the FDD Phy and the associated protocols Focus here

bull UTRAN-Universal Terrestrial Radio Access Network- is associated with the WCDMA radio Access Network

bull UMTS refers to the whole network

12 23

UMTS-FDD WCDMA

bull Wideband Direct Sequence Code Division Multiple Access

bull Does not assign a specific frequency to each user Instead every channel uses the full available spectrum

bull Individual conversations are encoded with a pseudo-random digital sequence

bull See httpwwwumtsworldcomtechnologyoverviewhtm

12 24

WCDMA Parameters

Channel BW 5 MHz

Forward RF Channel Structure Direct Spread

Chip Rate 384 Mcps

Frame Length 10 ms (38400 chips)

No of slotsframe 15

No of chipsslot 2560chips (Max 2560 bits)

Power Control Open and fast close loop (16 KHz)

Uplink Spreading Factor 4 to 256

Downlink Spreading Factor 4 to 512

12 25

Spreading Operation

bull Spreading means increasing the signal bandwidthbull Strictly speaking spreading includes two

operationsndash Channelisation (increases signal bandwidth) using

orthogonal codesndash Scrambling (does not affect the signal bandwidth) using

pseudo noise codes

12 26

Codes

Channellization Code Scrambling Code

Usage UL Separation of physical dataand control channels from same UEDL Separation of different userswithin one cell

UL Separation of terminalsDL Separation ofcellssectors

Length UL4-256 chipsDL4-512 chips

38400 chips

No of codes No of codes under one scrambling code= SF

UL Several millionDL 512

Code Family Orthogonal Variable Spreading Factor

Long 10ms code Gold codeShort code Extended S(2) code Family

Increase BW YES NO

12 27

UMTS Architecture

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

Cell site

Access Network

Core Network

User Equipment

12 28

UMTS Architecture

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 29

UMTS Architecture

bull User equipment-UEndash UMTS Subscriber Identity Module ndashUSIMndash Mobile Equipment- cell phone

bull UMTS Terrestrial Radio Access Networkndash Radio Network Subsystem

bull Node B- BSndash Transceiverndash Rate adaptationndash Radio resource managementndash Power control

12 30

UMTS Architecture

bull Radio Network Controller ndash RNCndash Radio access controlndash Connection controlndash Load congestion and admission controlndash Code allocation

ndash Core Networkbull MSCbull VLRbull HLRbull Gateway MSC ndash GMSC

ndash Supports circuit switched connectionsbull Serving GRPS Support Node ndash SGPRS

ndash Logical interface to UTRAN for packet transportraquo Session managementraquo Logical link management

bull Gateway GPRS Support Node ndash GGSNndash Supports packet switched transportndash This is an IP router

12 31

UMTS Protocol Architecture - User Plane

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

FP= Framing Protocol GTP-U= GPRS Tunneling Protocol-UserPDCP =Packet Data convergence Protocol

12 32

UMTS Protocol Stack

bull Radio Resource Control-RRC

bull Broadcastmulitcast control- BMC

bull Packet Data convergence Protocol- PDCPndash Header

compression

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

12 33

Packet SAR

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

12 34

Physical Layerbull The physical layer offers information transfer services to

the MAC layer These services are denoted as Transport channels (TrChrsquos) There are also Physical channels

bull Physical layer comprises following functionsndash 1048713 Various handover functionsndash 1048713 Error detection and report to higher layersndash 1048713 Multiplexing of transport channelsndash 1048713 Mapping of transport channels to physical channelsndash 1048713 Fast Close loop Power controlndash 1048713 Frequency and Time Synchronizationndash 1048713 Other responsibilities associated with transmitting and

receiving signals over the wireless mediandash Measurements

bull SIRbull Tx power Frame error rate etc

bull Physical channel is assigned a specific code

12 35

Transport amp Physical Channels

Transport Channel Physical Channel(ULDL) Dedicated Channel DCH Dedicated Physical Data Channel DPDCH

Dedicated Physical Control Channel DPCCH

(UL) Random Access Channel RACH Physical random access channel PRACH

(UL) Common packet channel CPCH Physical common packet channel PCPCH

(DL) Broadcast channel BCH Primary common control physical channel P-CCPCH

(DL) Forward access channel FACH(DL) Paging channel PCH

Secondary common control physical channel S-CCPCH

(DL) Downlink shared channel DSCH Physical downlink shared channel PDSCH

Signaling physical channels

Synchronization channel SCHCommon pilot channel CPICHAcquisition indication channel AICHPaging indication channel PICHCPCH Status indication channel CSICHCollision detectionChannel assignment indicator channel CDCA-ICH

12 36

UMTS FDD frame structure

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 37

MAC Layer

bull The MAC layer offers Data transfer to RLC and higher layers

bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically

bit rate within a predefined set per information unit delivered to the physical layer

ndash Service multiplexing on RACH FACH and dedicated channels

ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling

ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements

12 38

Physical Layer

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 39

RRC Layerbull The RRC layer offers the core network the following

servicesndash General control service which is used as an information

broadcast servicendash Notification service which is used for paging and

notification of a selected UEsndash Dedicated control service which is used for

establishmentrelease of a connection and transfer of messages using the connection

bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover

admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection

12 40

RLC Layer

bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is

appended to the information unit received from the higher layer

ndash Assured and un assured data transferbull The RLC layer comprises the following functions

ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the

WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the

control plane)ndash Duplicate detectionndash Flow controlndash Ciphering

12 41

RLC Layer-Modesbull Transparent-TM

ndash No header attachedndash SARndash SDU discard

bull Delete SDU if not sent before timer expiresndash Used for

bull Voicebull Some signaling

bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability

bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat

12 42

RLC Layer

From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the

UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

12 43

UE-Call states

bull Designed to ndash Take advantage of bursty nature of

datandash Save batter powerndash Maintains logical session and tracks

mobility but when appropriatendash releases dedicated resources to

increase overall capacityndash asleeps the UE

12 44

UE-Call states

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 45

UE-Call states

bull Idle modendash No active sessionndash UE monitors

Paging CHndash Sleeps between

paging cycles

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 46

UE-Call states

bull CELL_DCH state (Dedicated)ndash A dedicated physical

channel is allocated to the UE in uplink and downlink

ndash The UE is known on cell level according to its current active set

ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE

ndash Call typesbull Circuit Switched always in

this statebull Packet Switched in this

state if transferring large volume of data

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 47

UE-Call states

bull CELL_FACH state(Forward Access Ch)

ndash No dedicated physical channel is allocated to the UE

ndash The UE continuously monitors a FACH in the downlink

ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel

ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update

ndash Radio not put to sleepndash For packet switched sessions

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 48

UE-Call states

bull CELL_PCH state (Paging Ch)ndash No dedicated physical

channel is allocated to the UE

ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash Sleep between pagesndash A logical session is still upndash The position of the UE is

known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 49

UE-Call states

bull URA_PCH State ndash No dedicated channel is

allocated to the UEndash The UE selects a PCH with

the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state

ndash Similar to CELL_PCH state only the at the URA level

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 50

Power Control-PC

bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to

ensure that there is enough power for mobiles at the cell edge

bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control

commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command

ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break

12 51

Power Control

bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss

by means of a downlink beacon signalndash Provide a coarse initial power setting of

the mobile at the beginning of a connection

ndash Apply only prior to initiating the transmission on RACH or CPCH

12 52

Packet Access in WCDMA

bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection

bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared

bull RNC can decide when and how to send packets based on type of packet traffic

ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech

ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video

ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing

ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail

bull RNC can assign a packet to a specific channel

Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 53

Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the

downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft

handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts

bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts

bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink

orthogonal code is reserved according to maximum bit rate

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 54

Packet Access in WCDMA

bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner

bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer

bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate

bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and

bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 55

Packet Access in WCDMA

bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased

bull Advantagesndash resources are in full usage due to longer transmission

timendash small variation in interference levelndash longer uplink range due to lower bit rate

bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 56

Packet Access in WCDMA

bull Time division is normally used with shared channels and code division is normally used with dedicated channels

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 57

Packet Access in WCDMA

bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users

could be based on required transmission powerbull Users close to the BS requires less

transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate

bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput

bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 58

HSDPA amp Enhance Uplink

bull HSDPA = High Speed Downlink Packet Access

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 59

HSDPA amp Enhance Uplink

bull Remember it is better (more efficient) to have a large number of users sharing a single server

bull This lead to a desire to have fast allocation of shared resources

bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code

bull Uplink resourcesndash Interference at the BS

bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)

bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)

12 60

HSDPA amp Enhance Uplink

bull UTRAN Architecture with HSDPA and enhanced uplink

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 61

HSDPA amp Enhance Uplink

bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK

modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and

coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function

moved to Node-B (WCDMA packet scheduling was done in the RNC)

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 62

HSDPA amp Enhance Uplink

bull Gain in Performance

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 63

HSDPA

bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to

individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes

bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)

12 64

HSDPA

bull New frame structurendash Five subframesW-CDMA

framendash User data can be

assigned on a subframe basis

ndash System can adjust in 2ms

ndash Each subframe is a transmission time interval (TTI) = 2ms

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 65

HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared

resource is also in the time domain

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 66

HSDPA

bull Another view

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

Spreading Code

12 67

HSDPAbull Link Adaptation

ndash Remember the fast power control is commonly used to

bull Maintain constant EnergyNoise ratiobull Reduce effect of fading

ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant

EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 68

HSDPA

ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)

ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum

bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user

bull 1 ndash 2 Mbs closer to achievable under real conditions

12 69

HSDPA

bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE

bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms

bull CQI (0-30) each mapping into a modulation SF etc

bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression

bull

12 70

HSDPA

bull Schedulingndash The scheduler decides which user

should get access to each TTI ndash CQI provides input into a Scheduler

bull Proportional Fair (PF) Scheduler can be uses

bull Implementation Specific

12 71

HSDPA

bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number

of spreading codes limits rate not power so likely receive first transmission

ndash At greater distances move from BS see more errors IR will require additional transmission but not many

ndash HARQ only retransmit upon an ACK or NACK

12 72

HSDPA

From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007

12 73

HSDPA

bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2

ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent

Scheduling

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 14

Other Functions Power control CDMA

bull Purposendash Removes near far effectndash Mitigates fadingndash Compensates changes in propagation conditionsndash In the system level

bull decrease interference from other usersbull increase capacity of the system

bull Uplinkndash Power control in uplink must make signal powers

from different users nearly equal in order to maximize the total capacity in the cell

bull Downlinkndash In downlink the power control must keep the signal

at minimal required level in order to decrease the interference to users in other cells

12 15

Other Functions Power control CDMA

bull Typesndash Open loop

bull set initial power for MSbull Each MS sets power based on individual

measurementsbull Coarse scale

ndash Closed loopbull BS knows receive power from each MSbull BS can tell each MS to set its power to achieve

system goalsbull Fast power control can mitigate fast fadingbull Three steps

ndash Transmissionndash Measurementndash Feedback

12 16

3G

bull 1G Analog Cellular Phones Needs a modem 96 kbps max

bull 2G Digital Cellular Phones No modem required 193 kbps max

bull 25G General Packet Radio Service (GPRS) 144kbps Data only

bull 3G Future high-speed data with Voice 64 kbps to 2 Mbpsndash W-CDMAUMTS (Universal Mobile

Telecommunications Systemndash CDMA2000

12 17

Organizations

ndash 3GPP 3rd Generation Partnership Project

ndash 3GPP is responsible for writing and maintaining the UMTS specifications

ndash hellip CDMA2000 hellipndash Internet Engineering Task Force (IETF)

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 18

3G- Advantages

3G phones promise - bull Improved digital voice communications bull Larger Bandwidth ndash Higher Data ratebull Greater subscriber capacity bull Fast packet-based data services like e-mail

short message service (SMS) and Internet access at broadband speeds

bull Most carriers also expect consumers to want - ndash location services ndash interactive gaming ndash streaming video ndash home monitoring and control ndash and who knows what else while being fully mobile

anywhere in the world

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 19

3G Capabilitiesbull Voice quality comparable to the public

switched telephone networkbull 144 Kbps- user in high-speed motor vehiclesbull 384 Kbps- pedestrians standing or moving

slowly over small areasbull Up to 2 Mbps- fixed applications like office usebull Symmetricalasymmetrical data transmission

ratesbull Support for both packet switched and circuit

switched data services like Internet Protocol (IP) traffic and real time video

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 20

Technologies

bull 3G is superior to the other digital standards like-ndash GSM (Global System for Mobile) communications standard

used worldwide ndash And IS-136 TDMA standard used primarily in North America ndash IS-95 CDMA systems

bull 3G Technologies-

ndash WCDMA or UMTS-FDD (Universal Mobile Telecommunications System - Frequency Division Duplex)---Direct Spread

ndash CDMA2000 - 1x-EvDOEvDV---Multi carrier

ndash UMTS ndash TDD (Time Division Duplex) or TD-SCDMA (Time Division - Synchronous Code Division Multiple Access) ---Time Code

ndash CDMA2000 and WCDMA or UMTS-FDD have similar architectures

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 21

Evolution Paths

25G2G 3G

cdmaOneIS-95A

TDMA

cdmaOneIS-95B Cdma2000 1X

Cdma20001xEV-DV

Cdma20001xEV-DO

GSMGPRS

EDGE WCDMA

GSM Map Core Network

IS-41 Core Network

25G2G 3G

cdmaOneIS-95A

TDMA

cdmaOneIS-95B Cdma2000 1X

Cdma20001xEV-DV

Cdma20001xEV-DO

GSMGPRS

EDGE WCDMA

GSM Map Core Network

IS-41 Core Network

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 22

WCDMA

bull Spectrumndash 1920 MHz ndash 1980 MHz (uplink)ndash 2110 MHz ndash 2170 MHz (downlink)orndash 1850 MHz ndash 1910 MHz (uplink)ndash 1930 MHz ndash 1990 MHz (downlink)ndash Channel Spacing 5 Mhz

bull WCDMA is connected to the FDD Phy and the associated protocols Focus here

bull UTRAN-Universal Terrestrial Radio Access Network- is associated with the WCDMA radio Access Network

bull UMTS refers to the whole network

12 23

UMTS-FDD WCDMA

bull Wideband Direct Sequence Code Division Multiple Access

bull Does not assign a specific frequency to each user Instead every channel uses the full available spectrum

bull Individual conversations are encoded with a pseudo-random digital sequence

bull See httpwwwumtsworldcomtechnologyoverviewhtm

12 24

WCDMA Parameters

Channel BW 5 MHz

Forward RF Channel Structure Direct Spread

Chip Rate 384 Mcps

Frame Length 10 ms (38400 chips)

No of slotsframe 15

No of chipsslot 2560chips (Max 2560 bits)

Power Control Open and fast close loop (16 KHz)

Uplink Spreading Factor 4 to 256

Downlink Spreading Factor 4 to 512

12 25

Spreading Operation

bull Spreading means increasing the signal bandwidthbull Strictly speaking spreading includes two

operationsndash Channelisation (increases signal bandwidth) using

orthogonal codesndash Scrambling (does not affect the signal bandwidth) using

pseudo noise codes

12 26

Codes

Channellization Code Scrambling Code

Usage UL Separation of physical dataand control channels from same UEDL Separation of different userswithin one cell

UL Separation of terminalsDL Separation ofcellssectors

Length UL4-256 chipsDL4-512 chips

38400 chips

No of codes No of codes under one scrambling code= SF

UL Several millionDL 512

Code Family Orthogonal Variable Spreading Factor

Long 10ms code Gold codeShort code Extended S(2) code Family

Increase BW YES NO

12 27

UMTS Architecture

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

Cell site

Access Network

Core Network

User Equipment

12 28

UMTS Architecture

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 29

UMTS Architecture

bull User equipment-UEndash UMTS Subscriber Identity Module ndashUSIMndash Mobile Equipment- cell phone

bull UMTS Terrestrial Radio Access Networkndash Radio Network Subsystem

bull Node B- BSndash Transceiverndash Rate adaptationndash Radio resource managementndash Power control

12 30

UMTS Architecture

bull Radio Network Controller ndash RNCndash Radio access controlndash Connection controlndash Load congestion and admission controlndash Code allocation

ndash Core Networkbull MSCbull VLRbull HLRbull Gateway MSC ndash GMSC

ndash Supports circuit switched connectionsbull Serving GRPS Support Node ndash SGPRS

ndash Logical interface to UTRAN for packet transportraquo Session managementraquo Logical link management

bull Gateway GPRS Support Node ndash GGSNndash Supports packet switched transportndash This is an IP router

12 31

UMTS Protocol Architecture - User Plane

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

FP= Framing Protocol GTP-U= GPRS Tunneling Protocol-UserPDCP =Packet Data convergence Protocol

12 32

UMTS Protocol Stack

bull Radio Resource Control-RRC

bull Broadcastmulitcast control- BMC

bull Packet Data convergence Protocol- PDCPndash Header

compression

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

12 33

Packet SAR

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

12 34

Physical Layerbull The physical layer offers information transfer services to

the MAC layer These services are denoted as Transport channels (TrChrsquos) There are also Physical channels

bull Physical layer comprises following functionsndash 1048713 Various handover functionsndash 1048713 Error detection and report to higher layersndash 1048713 Multiplexing of transport channelsndash 1048713 Mapping of transport channels to physical channelsndash 1048713 Fast Close loop Power controlndash 1048713 Frequency and Time Synchronizationndash 1048713 Other responsibilities associated with transmitting and

receiving signals over the wireless mediandash Measurements

bull SIRbull Tx power Frame error rate etc

bull Physical channel is assigned a specific code

12 35

Transport amp Physical Channels

Transport Channel Physical Channel(ULDL) Dedicated Channel DCH Dedicated Physical Data Channel DPDCH

Dedicated Physical Control Channel DPCCH

(UL) Random Access Channel RACH Physical random access channel PRACH

(UL) Common packet channel CPCH Physical common packet channel PCPCH

(DL) Broadcast channel BCH Primary common control physical channel P-CCPCH

(DL) Forward access channel FACH(DL) Paging channel PCH

Secondary common control physical channel S-CCPCH

(DL) Downlink shared channel DSCH Physical downlink shared channel PDSCH

Signaling physical channels

Synchronization channel SCHCommon pilot channel CPICHAcquisition indication channel AICHPaging indication channel PICHCPCH Status indication channel CSICHCollision detectionChannel assignment indicator channel CDCA-ICH

12 36

UMTS FDD frame structure

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 37

MAC Layer

bull The MAC layer offers Data transfer to RLC and higher layers

bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically

bit rate within a predefined set per information unit delivered to the physical layer

ndash Service multiplexing on RACH FACH and dedicated channels

ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling

ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements

12 38

Physical Layer

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 39

RRC Layerbull The RRC layer offers the core network the following

servicesndash General control service which is used as an information

broadcast servicendash Notification service which is used for paging and

notification of a selected UEsndash Dedicated control service which is used for

establishmentrelease of a connection and transfer of messages using the connection

bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover

admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection

12 40

RLC Layer

bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is

appended to the information unit received from the higher layer

ndash Assured and un assured data transferbull The RLC layer comprises the following functions

ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the

WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the

control plane)ndash Duplicate detectionndash Flow controlndash Ciphering

12 41

RLC Layer-Modesbull Transparent-TM

ndash No header attachedndash SARndash SDU discard

bull Delete SDU if not sent before timer expiresndash Used for

bull Voicebull Some signaling

bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability

bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat

12 42

RLC Layer

From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the

UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

12 43

UE-Call states

bull Designed to ndash Take advantage of bursty nature of

datandash Save batter powerndash Maintains logical session and tracks

mobility but when appropriatendash releases dedicated resources to

increase overall capacityndash asleeps the UE

12 44

UE-Call states

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 45

UE-Call states

bull Idle modendash No active sessionndash UE monitors

Paging CHndash Sleeps between

paging cycles

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 46

UE-Call states

bull CELL_DCH state (Dedicated)ndash A dedicated physical

channel is allocated to the UE in uplink and downlink

ndash The UE is known on cell level according to its current active set

ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE

ndash Call typesbull Circuit Switched always in

this statebull Packet Switched in this

state if transferring large volume of data

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 47

UE-Call states

bull CELL_FACH state(Forward Access Ch)

ndash No dedicated physical channel is allocated to the UE

ndash The UE continuously monitors a FACH in the downlink

ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel

ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update

ndash Radio not put to sleepndash For packet switched sessions

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 48

UE-Call states

bull CELL_PCH state (Paging Ch)ndash No dedicated physical

channel is allocated to the UE

ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash Sleep between pagesndash A logical session is still upndash The position of the UE is

known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 49

UE-Call states

bull URA_PCH State ndash No dedicated channel is

allocated to the UEndash The UE selects a PCH with

the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state

ndash Similar to CELL_PCH state only the at the URA level

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 50

Power Control-PC

bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to

ensure that there is enough power for mobiles at the cell edge

bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control

commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command

ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break

12 51

Power Control

bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss

by means of a downlink beacon signalndash Provide a coarse initial power setting of

the mobile at the beginning of a connection

ndash Apply only prior to initiating the transmission on RACH or CPCH

12 52

Packet Access in WCDMA

bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection

bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared

bull RNC can decide when and how to send packets based on type of packet traffic

ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech

ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video

ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing

ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail

bull RNC can assign a packet to a specific channel

Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 53

Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the

downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft

handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts

bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts

bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink

orthogonal code is reserved according to maximum bit rate

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 54

Packet Access in WCDMA

bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner

bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer

bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate

bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and

bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 55

Packet Access in WCDMA

bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased

bull Advantagesndash resources are in full usage due to longer transmission

timendash small variation in interference levelndash longer uplink range due to lower bit rate

bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 56

Packet Access in WCDMA

bull Time division is normally used with shared channels and code division is normally used with dedicated channels

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 57

Packet Access in WCDMA

bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users

could be based on required transmission powerbull Users close to the BS requires less

transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate

bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput

bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 58

HSDPA amp Enhance Uplink

bull HSDPA = High Speed Downlink Packet Access

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 59

HSDPA amp Enhance Uplink

bull Remember it is better (more efficient) to have a large number of users sharing a single server

bull This lead to a desire to have fast allocation of shared resources

bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code

bull Uplink resourcesndash Interference at the BS

bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)

bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)

12 60

HSDPA amp Enhance Uplink

bull UTRAN Architecture with HSDPA and enhanced uplink

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 61

HSDPA amp Enhance Uplink

bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK

modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and

coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function

moved to Node-B (WCDMA packet scheduling was done in the RNC)

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 62

HSDPA amp Enhance Uplink

bull Gain in Performance

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 63

HSDPA

bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to

individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes

bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)

12 64

HSDPA

bull New frame structurendash Five subframesW-CDMA

framendash User data can be

assigned on a subframe basis

ndash System can adjust in 2ms

ndash Each subframe is a transmission time interval (TTI) = 2ms

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 65

HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared

resource is also in the time domain

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 66

HSDPA

bull Another view

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

Spreading Code

12 67

HSDPAbull Link Adaptation

ndash Remember the fast power control is commonly used to

bull Maintain constant EnergyNoise ratiobull Reduce effect of fading

ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant

EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 68

HSDPA

ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)

ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum

bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user

bull 1 ndash 2 Mbs closer to achievable under real conditions

12 69

HSDPA

bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE

bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms

bull CQI (0-30) each mapping into a modulation SF etc

bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression

bull

12 70

HSDPA

bull Schedulingndash The scheduler decides which user

should get access to each TTI ndash CQI provides input into a Scheduler

bull Proportional Fair (PF) Scheduler can be uses

bull Implementation Specific

12 71

HSDPA

bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number

of spreading codes limits rate not power so likely receive first transmission

ndash At greater distances move from BS see more errors IR will require additional transmission but not many

ndash HARQ only retransmit upon an ACK or NACK

12 72

HSDPA

From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007

12 73

HSDPA

bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2

ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent

Scheduling

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 15

Other Functions Power control CDMA

bull Typesndash Open loop

bull set initial power for MSbull Each MS sets power based on individual

measurementsbull Coarse scale

ndash Closed loopbull BS knows receive power from each MSbull BS can tell each MS to set its power to achieve

system goalsbull Fast power control can mitigate fast fadingbull Three steps

ndash Transmissionndash Measurementndash Feedback

12 16

3G

bull 1G Analog Cellular Phones Needs a modem 96 kbps max

bull 2G Digital Cellular Phones No modem required 193 kbps max

bull 25G General Packet Radio Service (GPRS) 144kbps Data only

bull 3G Future high-speed data with Voice 64 kbps to 2 Mbpsndash W-CDMAUMTS (Universal Mobile

Telecommunications Systemndash CDMA2000

12 17

Organizations

ndash 3GPP 3rd Generation Partnership Project

ndash 3GPP is responsible for writing and maintaining the UMTS specifications

ndash hellip CDMA2000 hellipndash Internet Engineering Task Force (IETF)

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 18

3G- Advantages

3G phones promise - bull Improved digital voice communications bull Larger Bandwidth ndash Higher Data ratebull Greater subscriber capacity bull Fast packet-based data services like e-mail

short message service (SMS) and Internet access at broadband speeds

bull Most carriers also expect consumers to want - ndash location services ndash interactive gaming ndash streaming video ndash home monitoring and control ndash and who knows what else while being fully mobile

anywhere in the world

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 19

3G Capabilitiesbull Voice quality comparable to the public

switched telephone networkbull 144 Kbps- user in high-speed motor vehiclesbull 384 Kbps- pedestrians standing or moving

slowly over small areasbull Up to 2 Mbps- fixed applications like office usebull Symmetricalasymmetrical data transmission

ratesbull Support for both packet switched and circuit

switched data services like Internet Protocol (IP) traffic and real time video

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 20

Technologies

bull 3G is superior to the other digital standards like-ndash GSM (Global System for Mobile) communications standard

used worldwide ndash And IS-136 TDMA standard used primarily in North America ndash IS-95 CDMA systems

bull 3G Technologies-

ndash WCDMA or UMTS-FDD (Universal Mobile Telecommunications System - Frequency Division Duplex)---Direct Spread

ndash CDMA2000 - 1x-EvDOEvDV---Multi carrier

ndash UMTS ndash TDD (Time Division Duplex) or TD-SCDMA (Time Division - Synchronous Code Division Multiple Access) ---Time Code

ndash CDMA2000 and WCDMA or UMTS-FDD have similar architectures

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 21

Evolution Paths

25G2G 3G

cdmaOneIS-95A

TDMA

cdmaOneIS-95B Cdma2000 1X

Cdma20001xEV-DV

Cdma20001xEV-DO

GSMGPRS

EDGE WCDMA

GSM Map Core Network

IS-41 Core Network

25G2G 3G

cdmaOneIS-95A

TDMA

cdmaOneIS-95B Cdma2000 1X

Cdma20001xEV-DV

Cdma20001xEV-DO

GSMGPRS

EDGE WCDMA

GSM Map Core Network

IS-41 Core Network

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 22

WCDMA

bull Spectrumndash 1920 MHz ndash 1980 MHz (uplink)ndash 2110 MHz ndash 2170 MHz (downlink)orndash 1850 MHz ndash 1910 MHz (uplink)ndash 1930 MHz ndash 1990 MHz (downlink)ndash Channel Spacing 5 Mhz

bull WCDMA is connected to the FDD Phy and the associated protocols Focus here

bull UTRAN-Universal Terrestrial Radio Access Network- is associated with the WCDMA radio Access Network

bull UMTS refers to the whole network

12 23

UMTS-FDD WCDMA

bull Wideband Direct Sequence Code Division Multiple Access

bull Does not assign a specific frequency to each user Instead every channel uses the full available spectrum

bull Individual conversations are encoded with a pseudo-random digital sequence

bull See httpwwwumtsworldcomtechnologyoverviewhtm

12 24

WCDMA Parameters

Channel BW 5 MHz

Forward RF Channel Structure Direct Spread

Chip Rate 384 Mcps

Frame Length 10 ms (38400 chips)

No of slotsframe 15

No of chipsslot 2560chips (Max 2560 bits)

Power Control Open and fast close loop (16 KHz)

Uplink Spreading Factor 4 to 256

Downlink Spreading Factor 4 to 512

12 25

Spreading Operation

bull Spreading means increasing the signal bandwidthbull Strictly speaking spreading includes two

operationsndash Channelisation (increases signal bandwidth) using

orthogonal codesndash Scrambling (does not affect the signal bandwidth) using

pseudo noise codes

12 26

Codes

Channellization Code Scrambling Code

Usage UL Separation of physical dataand control channels from same UEDL Separation of different userswithin one cell

UL Separation of terminalsDL Separation ofcellssectors

Length UL4-256 chipsDL4-512 chips

38400 chips

No of codes No of codes under one scrambling code= SF

UL Several millionDL 512

Code Family Orthogonal Variable Spreading Factor

Long 10ms code Gold codeShort code Extended S(2) code Family

Increase BW YES NO

12 27

UMTS Architecture

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

Cell site

Access Network

Core Network

User Equipment

12 28

UMTS Architecture

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 29

UMTS Architecture

bull User equipment-UEndash UMTS Subscriber Identity Module ndashUSIMndash Mobile Equipment- cell phone

bull UMTS Terrestrial Radio Access Networkndash Radio Network Subsystem

bull Node B- BSndash Transceiverndash Rate adaptationndash Radio resource managementndash Power control

12 30

UMTS Architecture

bull Radio Network Controller ndash RNCndash Radio access controlndash Connection controlndash Load congestion and admission controlndash Code allocation

ndash Core Networkbull MSCbull VLRbull HLRbull Gateway MSC ndash GMSC

ndash Supports circuit switched connectionsbull Serving GRPS Support Node ndash SGPRS

ndash Logical interface to UTRAN for packet transportraquo Session managementraquo Logical link management

bull Gateway GPRS Support Node ndash GGSNndash Supports packet switched transportndash This is an IP router

12 31

UMTS Protocol Architecture - User Plane

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

FP= Framing Protocol GTP-U= GPRS Tunneling Protocol-UserPDCP =Packet Data convergence Protocol

12 32

UMTS Protocol Stack

bull Radio Resource Control-RRC

bull Broadcastmulitcast control- BMC

bull Packet Data convergence Protocol- PDCPndash Header

compression

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

12 33

Packet SAR

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

12 34

Physical Layerbull The physical layer offers information transfer services to

the MAC layer These services are denoted as Transport channels (TrChrsquos) There are also Physical channels

bull Physical layer comprises following functionsndash 1048713 Various handover functionsndash 1048713 Error detection and report to higher layersndash 1048713 Multiplexing of transport channelsndash 1048713 Mapping of transport channels to physical channelsndash 1048713 Fast Close loop Power controlndash 1048713 Frequency and Time Synchronizationndash 1048713 Other responsibilities associated with transmitting and

receiving signals over the wireless mediandash Measurements

bull SIRbull Tx power Frame error rate etc

bull Physical channel is assigned a specific code

12 35

Transport amp Physical Channels

Transport Channel Physical Channel(ULDL) Dedicated Channel DCH Dedicated Physical Data Channel DPDCH

Dedicated Physical Control Channel DPCCH

(UL) Random Access Channel RACH Physical random access channel PRACH

(UL) Common packet channel CPCH Physical common packet channel PCPCH

(DL) Broadcast channel BCH Primary common control physical channel P-CCPCH

(DL) Forward access channel FACH(DL) Paging channel PCH

Secondary common control physical channel S-CCPCH

(DL) Downlink shared channel DSCH Physical downlink shared channel PDSCH

Signaling physical channels

Synchronization channel SCHCommon pilot channel CPICHAcquisition indication channel AICHPaging indication channel PICHCPCH Status indication channel CSICHCollision detectionChannel assignment indicator channel CDCA-ICH

12 36

UMTS FDD frame structure

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 37

MAC Layer

bull The MAC layer offers Data transfer to RLC and higher layers

bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically

bit rate within a predefined set per information unit delivered to the physical layer

ndash Service multiplexing on RACH FACH and dedicated channels

ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling

ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements

12 38

Physical Layer

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 39

RRC Layerbull The RRC layer offers the core network the following

servicesndash General control service which is used as an information

broadcast servicendash Notification service which is used for paging and

notification of a selected UEsndash Dedicated control service which is used for

establishmentrelease of a connection and transfer of messages using the connection

bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover

admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection

12 40

RLC Layer

bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is

appended to the information unit received from the higher layer

ndash Assured and un assured data transferbull The RLC layer comprises the following functions

ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the

WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the

control plane)ndash Duplicate detectionndash Flow controlndash Ciphering

12 41

RLC Layer-Modesbull Transparent-TM

ndash No header attachedndash SARndash SDU discard

bull Delete SDU if not sent before timer expiresndash Used for

bull Voicebull Some signaling

bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability

bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat

12 42

RLC Layer

From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the

UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

12 43

UE-Call states

bull Designed to ndash Take advantage of bursty nature of

datandash Save batter powerndash Maintains logical session and tracks

mobility but when appropriatendash releases dedicated resources to

increase overall capacityndash asleeps the UE

12 44

UE-Call states

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 45

UE-Call states

bull Idle modendash No active sessionndash UE monitors

Paging CHndash Sleeps between

paging cycles

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 46

UE-Call states

bull CELL_DCH state (Dedicated)ndash A dedicated physical

channel is allocated to the UE in uplink and downlink

ndash The UE is known on cell level according to its current active set

ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE

ndash Call typesbull Circuit Switched always in

this statebull Packet Switched in this

state if transferring large volume of data

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 47

UE-Call states

bull CELL_FACH state(Forward Access Ch)

ndash No dedicated physical channel is allocated to the UE

ndash The UE continuously monitors a FACH in the downlink

ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel

ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update

ndash Radio not put to sleepndash For packet switched sessions

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 48

UE-Call states

bull CELL_PCH state (Paging Ch)ndash No dedicated physical

channel is allocated to the UE

ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash Sleep between pagesndash A logical session is still upndash The position of the UE is

known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 49

UE-Call states

bull URA_PCH State ndash No dedicated channel is

allocated to the UEndash The UE selects a PCH with

the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state

ndash Similar to CELL_PCH state only the at the URA level

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 50

Power Control-PC

bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to

ensure that there is enough power for mobiles at the cell edge

bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control

commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command

ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break

12 51

Power Control

bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss

by means of a downlink beacon signalndash Provide a coarse initial power setting of

the mobile at the beginning of a connection

ndash Apply only prior to initiating the transmission on RACH or CPCH

12 52

Packet Access in WCDMA

bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection

bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared

bull RNC can decide when and how to send packets based on type of packet traffic

ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech

ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video

ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing

ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail

bull RNC can assign a packet to a specific channel

Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 53

Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the

downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft

handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts

bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts

bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink

orthogonal code is reserved according to maximum bit rate

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 54

Packet Access in WCDMA

bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner

bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer

bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate

bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and

bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 55

Packet Access in WCDMA

bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased

bull Advantagesndash resources are in full usage due to longer transmission

timendash small variation in interference levelndash longer uplink range due to lower bit rate

bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 56

Packet Access in WCDMA

bull Time division is normally used with shared channels and code division is normally used with dedicated channels

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 57

Packet Access in WCDMA

bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users

could be based on required transmission powerbull Users close to the BS requires less

transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate

bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput

bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 58

HSDPA amp Enhance Uplink

bull HSDPA = High Speed Downlink Packet Access

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 59

HSDPA amp Enhance Uplink

bull Remember it is better (more efficient) to have a large number of users sharing a single server

bull This lead to a desire to have fast allocation of shared resources

bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code

bull Uplink resourcesndash Interference at the BS

bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)

bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)

12 60

HSDPA amp Enhance Uplink

bull UTRAN Architecture with HSDPA and enhanced uplink

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 61

HSDPA amp Enhance Uplink

bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK

modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and

coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function

moved to Node-B (WCDMA packet scheduling was done in the RNC)

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 62

HSDPA amp Enhance Uplink

bull Gain in Performance

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 63

HSDPA

bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to

individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes

bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)

12 64

HSDPA

bull New frame structurendash Five subframesW-CDMA

framendash User data can be

assigned on a subframe basis

ndash System can adjust in 2ms

ndash Each subframe is a transmission time interval (TTI) = 2ms

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 65

HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared

resource is also in the time domain

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 66

HSDPA

bull Another view

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

Spreading Code

12 67

HSDPAbull Link Adaptation

ndash Remember the fast power control is commonly used to

bull Maintain constant EnergyNoise ratiobull Reduce effect of fading

ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant

EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 68

HSDPA

ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)

ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum

bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user

bull 1 ndash 2 Mbs closer to achievable under real conditions

12 69

HSDPA

bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE

bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms

bull CQI (0-30) each mapping into a modulation SF etc

bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression

bull

12 70

HSDPA

bull Schedulingndash The scheduler decides which user

should get access to each TTI ndash CQI provides input into a Scheduler

bull Proportional Fair (PF) Scheduler can be uses

bull Implementation Specific

12 71

HSDPA

bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number

of spreading codes limits rate not power so likely receive first transmission

ndash At greater distances move from BS see more errors IR will require additional transmission but not many

ndash HARQ only retransmit upon an ACK or NACK

12 72

HSDPA

From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007

12 73

HSDPA

bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2

ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent

Scheduling

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 16

3G

bull 1G Analog Cellular Phones Needs a modem 96 kbps max

bull 2G Digital Cellular Phones No modem required 193 kbps max

bull 25G General Packet Radio Service (GPRS) 144kbps Data only

bull 3G Future high-speed data with Voice 64 kbps to 2 Mbpsndash W-CDMAUMTS (Universal Mobile

Telecommunications Systemndash CDMA2000

12 17

Organizations

ndash 3GPP 3rd Generation Partnership Project

ndash 3GPP is responsible for writing and maintaining the UMTS specifications

ndash hellip CDMA2000 hellipndash Internet Engineering Task Force (IETF)

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 18

3G- Advantages

3G phones promise - bull Improved digital voice communications bull Larger Bandwidth ndash Higher Data ratebull Greater subscriber capacity bull Fast packet-based data services like e-mail

short message service (SMS) and Internet access at broadband speeds

bull Most carriers also expect consumers to want - ndash location services ndash interactive gaming ndash streaming video ndash home monitoring and control ndash and who knows what else while being fully mobile

anywhere in the world

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 19

3G Capabilitiesbull Voice quality comparable to the public

switched telephone networkbull 144 Kbps- user in high-speed motor vehiclesbull 384 Kbps- pedestrians standing or moving

slowly over small areasbull Up to 2 Mbps- fixed applications like office usebull Symmetricalasymmetrical data transmission

ratesbull Support for both packet switched and circuit

switched data services like Internet Protocol (IP) traffic and real time video

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 20

Technologies

bull 3G is superior to the other digital standards like-ndash GSM (Global System for Mobile) communications standard

used worldwide ndash And IS-136 TDMA standard used primarily in North America ndash IS-95 CDMA systems

bull 3G Technologies-

ndash WCDMA or UMTS-FDD (Universal Mobile Telecommunications System - Frequency Division Duplex)---Direct Spread

ndash CDMA2000 - 1x-EvDOEvDV---Multi carrier

ndash UMTS ndash TDD (Time Division Duplex) or TD-SCDMA (Time Division - Synchronous Code Division Multiple Access) ---Time Code

ndash CDMA2000 and WCDMA or UMTS-FDD have similar architectures

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 21

Evolution Paths

25G2G 3G

cdmaOneIS-95A

TDMA

cdmaOneIS-95B Cdma2000 1X

Cdma20001xEV-DV

Cdma20001xEV-DO

GSMGPRS

EDGE WCDMA

GSM Map Core Network

IS-41 Core Network

25G2G 3G

cdmaOneIS-95A

TDMA

cdmaOneIS-95B Cdma2000 1X

Cdma20001xEV-DV

Cdma20001xEV-DO

GSMGPRS

EDGE WCDMA

GSM Map Core Network

IS-41 Core Network

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 22

WCDMA

bull Spectrumndash 1920 MHz ndash 1980 MHz (uplink)ndash 2110 MHz ndash 2170 MHz (downlink)orndash 1850 MHz ndash 1910 MHz (uplink)ndash 1930 MHz ndash 1990 MHz (downlink)ndash Channel Spacing 5 Mhz

bull WCDMA is connected to the FDD Phy and the associated protocols Focus here

bull UTRAN-Universal Terrestrial Radio Access Network- is associated with the WCDMA radio Access Network

bull UMTS refers to the whole network

12 23

UMTS-FDD WCDMA

bull Wideband Direct Sequence Code Division Multiple Access

bull Does not assign a specific frequency to each user Instead every channel uses the full available spectrum

bull Individual conversations are encoded with a pseudo-random digital sequence

bull See httpwwwumtsworldcomtechnologyoverviewhtm

12 24

WCDMA Parameters

Channel BW 5 MHz

Forward RF Channel Structure Direct Spread

Chip Rate 384 Mcps

Frame Length 10 ms (38400 chips)

No of slotsframe 15

No of chipsslot 2560chips (Max 2560 bits)

Power Control Open and fast close loop (16 KHz)

Uplink Spreading Factor 4 to 256

Downlink Spreading Factor 4 to 512

12 25

Spreading Operation

bull Spreading means increasing the signal bandwidthbull Strictly speaking spreading includes two

operationsndash Channelisation (increases signal bandwidth) using

orthogonal codesndash Scrambling (does not affect the signal bandwidth) using

pseudo noise codes

12 26

Codes

Channellization Code Scrambling Code

Usage UL Separation of physical dataand control channels from same UEDL Separation of different userswithin one cell

UL Separation of terminalsDL Separation ofcellssectors

Length UL4-256 chipsDL4-512 chips

38400 chips

No of codes No of codes under one scrambling code= SF

UL Several millionDL 512

Code Family Orthogonal Variable Spreading Factor

Long 10ms code Gold codeShort code Extended S(2) code Family

Increase BW YES NO

12 27

UMTS Architecture

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

Cell site

Access Network

Core Network

User Equipment

12 28

UMTS Architecture

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 29

UMTS Architecture

bull User equipment-UEndash UMTS Subscriber Identity Module ndashUSIMndash Mobile Equipment- cell phone

bull UMTS Terrestrial Radio Access Networkndash Radio Network Subsystem

bull Node B- BSndash Transceiverndash Rate adaptationndash Radio resource managementndash Power control

12 30

UMTS Architecture

bull Radio Network Controller ndash RNCndash Radio access controlndash Connection controlndash Load congestion and admission controlndash Code allocation

ndash Core Networkbull MSCbull VLRbull HLRbull Gateway MSC ndash GMSC

ndash Supports circuit switched connectionsbull Serving GRPS Support Node ndash SGPRS

ndash Logical interface to UTRAN for packet transportraquo Session managementraquo Logical link management

bull Gateway GPRS Support Node ndash GGSNndash Supports packet switched transportndash This is an IP router

12 31

UMTS Protocol Architecture - User Plane

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

FP= Framing Protocol GTP-U= GPRS Tunneling Protocol-UserPDCP =Packet Data convergence Protocol

12 32

UMTS Protocol Stack

bull Radio Resource Control-RRC

bull Broadcastmulitcast control- BMC

bull Packet Data convergence Protocol- PDCPndash Header

compression

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

12 33

Packet SAR

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

12 34

Physical Layerbull The physical layer offers information transfer services to

the MAC layer These services are denoted as Transport channels (TrChrsquos) There are also Physical channels

bull Physical layer comprises following functionsndash 1048713 Various handover functionsndash 1048713 Error detection and report to higher layersndash 1048713 Multiplexing of transport channelsndash 1048713 Mapping of transport channels to physical channelsndash 1048713 Fast Close loop Power controlndash 1048713 Frequency and Time Synchronizationndash 1048713 Other responsibilities associated with transmitting and

receiving signals over the wireless mediandash Measurements

bull SIRbull Tx power Frame error rate etc

bull Physical channel is assigned a specific code

12 35

Transport amp Physical Channels

Transport Channel Physical Channel(ULDL) Dedicated Channel DCH Dedicated Physical Data Channel DPDCH

Dedicated Physical Control Channel DPCCH

(UL) Random Access Channel RACH Physical random access channel PRACH

(UL) Common packet channel CPCH Physical common packet channel PCPCH

(DL) Broadcast channel BCH Primary common control physical channel P-CCPCH

(DL) Forward access channel FACH(DL) Paging channel PCH

Secondary common control physical channel S-CCPCH

(DL) Downlink shared channel DSCH Physical downlink shared channel PDSCH

Signaling physical channels

Synchronization channel SCHCommon pilot channel CPICHAcquisition indication channel AICHPaging indication channel PICHCPCH Status indication channel CSICHCollision detectionChannel assignment indicator channel CDCA-ICH

12 36

UMTS FDD frame structure

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 37

MAC Layer

bull The MAC layer offers Data transfer to RLC and higher layers

bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically

bit rate within a predefined set per information unit delivered to the physical layer

ndash Service multiplexing on RACH FACH and dedicated channels

ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling

ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements

12 38

Physical Layer

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 39

RRC Layerbull The RRC layer offers the core network the following

servicesndash General control service which is used as an information

broadcast servicendash Notification service which is used for paging and

notification of a selected UEsndash Dedicated control service which is used for

establishmentrelease of a connection and transfer of messages using the connection

bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover

admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection

12 40

RLC Layer

bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is

appended to the information unit received from the higher layer

ndash Assured and un assured data transferbull The RLC layer comprises the following functions

ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the

WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the

control plane)ndash Duplicate detectionndash Flow controlndash Ciphering

12 41

RLC Layer-Modesbull Transparent-TM

ndash No header attachedndash SARndash SDU discard

bull Delete SDU if not sent before timer expiresndash Used for

bull Voicebull Some signaling

bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability

bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat

12 42

RLC Layer

From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the

UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

12 43

UE-Call states

bull Designed to ndash Take advantage of bursty nature of

datandash Save batter powerndash Maintains logical session and tracks

mobility but when appropriatendash releases dedicated resources to

increase overall capacityndash asleeps the UE

12 44

UE-Call states

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 45

UE-Call states

bull Idle modendash No active sessionndash UE monitors

Paging CHndash Sleeps between

paging cycles

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 46

UE-Call states

bull CELL_DCH state (Dedicated)ndash A dedicated physical

channel is allocated to the UE in uplink and downlink

ndash The UE is known on cell level according to its current active set

ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE

ndash Call typesbull Circuit Switched always in

this statebull Packet Switched in this

state if transferring large volume of data

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 47

UE-Call states

bull CELL_FACH state(Forward Access Ch)

ndash No dedicated physical channel is allocated to the UE

ndash The UE continuously monitors a FACH in the downlink

ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel

ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update

ndash Radio not put to sleepndash For packet switched sessions

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 48

UE-Call states

bull CELL_PCH state (Paging Ch)ndash No dedicated physical

channel is allocated to the UE

ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash Sleep between pagesndash A logical session is still upndash The position of the UE is

known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 49

UE-Call states

bull URA_PCH State ndash No dedicated channel is

allocated to the UEndash The UE selects a PCH with

the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state

ndash Similar to CELL_PCH state only the at the URA level

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 50

Power Control-PC

bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to

ensure that there is enough power for mobiles at the cell edge

bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control

commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command

ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break

12 51

Power Control

bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss

by means of a downlink beacon signalndash Provide a coarse initial power setting of

the mobile at the beginning of a connection

ndash Apply only prior to initiating the transmission on RACH or CPCH

12 52

Packet Access in WCDMA

bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection

bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared

bull RNC can decide when and how to send packets based on type of packet traffic

ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech

ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video

ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing

ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail

bull RNC can assign a packet to a specific channel

Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 53

Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the

downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft

handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts

bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts

bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink

orthogonal code is reserved according to maximum bit rate

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 54

Packet Access in WCDMA

bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner

bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer

bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate

bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and

bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 55

Packet Access in WCDMA

bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased

bull Advantagesndash resources are in full usage due to longer transmission

timendash small variation in interference levelndash longer uplink range due to lower bit rate

bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 56

Packet Access in WCDMA

bull Time division is normally used with shared channels and code division is normally used with dedicated channels

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 57

Packet Access in WCDMA

bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users

could be based on required transmission powerbull Users close to the BS requires less

transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate

bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput

bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 58

HSDPA amp Enhance Uplink

bull HSDPA = High Speed Downlink Packet Access

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 59

HSDPA amp Enhance Uplink

bull Remember it is better (more efficient) to have a large number of users sharing a single server

bull This lead to a desire to have fast allocation of shared resources

bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code

bull Uplink resourcesndash Interference at the BS

bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)

bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)

12 60

HSDPA amp Enhance Uplink

bull UTRAN Architecture with HSDPA and enhanced uplink

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 61

HSDPA amp Enhance Uplink

bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK

modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and

coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function

moved to Node-B (WCDMA packet scheduling was done in the RNC)

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 62

HSDPA amp Enhance Uplink

bull Gain in Performance

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 63

HSDPA

bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to

individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes

bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)

12 64

HSDPA

bull New frame structurendash Five subframesW-CDMA

framendash User data can be

assigned on a subframe basis

ndash System can adjust in 2ms

ndash Each subframe is a transmission time interval (TTI) = 2ms

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 65

HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared

resource is also in the time domain

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 66

HSDPA

bull Another view

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

Spreading Code

12 67

HSDPAbull Link Adaptation

ndash Remember the fast power control is commonly used to

bull Maintain constant EnergyNoise ratiobull Reduce effect of fading

ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant

EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 68

HSDPA

ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)

ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum

bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user

bull 1 ndash 2 Mbs closer to achievable under real conditions

12 69

HSDPA

bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE

bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms

bull CQI (0-30) each mapping into a modulation SF etc

bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression

bull

12 70

HSDPA

bull Schedulingndash The scheduler decides which user

should get access to each TTI ndash CQI provides input into a Scheduler

bull Proportional Fair (PF) Scheduler can be uses

bull Implementation Specific

12 71

HSDPA

bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number

of spreading codes limits rate not power so likely receive first transmission

ndash At greater distances move from BS see more errors IR will require additional transmission but not many

ndash HARQ only retransmit upon an ACK or NACK

12 72

HSDPA

From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007

12 73

HSDPA

bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2

ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent

Scheduling

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 17

Organizations

ndash 3GPP 3rd Generation Partnership Project

ndash 3GPP is responsible for writing and maintaining the UMTS specifications

ndash hellip CDMA2000 hellipndash Internet Engineering Task Force (IETF)

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 18

3G- Advantages

3G phones promise - bull Improved digital voice communications bull Larger Bandwidth ndash Higher Data ratebull Greater subscriber capacity bull Fast packet-based data services like e-mail

short message service (SMS) and Internet access at broadband speeds

bull Most carriers also expect consumers to want - ndash location services ndash interactive gaming ndash streaming video ndash home monitoring and control ndash and who knows what else while being fully mobile

anywhere in the world

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 19

3G Capabilitiesbull Voice quality comparable to the public

switched telephone networkbull 144 Kbps- user in high-speed motor vehiclesbull 384 Kbps- pedestrians standing or moving

slowly over small areasbull Up to 2 Mbps- fixed applications like office usebull Symmetricalasymmetrical data transmission

ratesbull Support for both packet switched and circuit

switched data services like Internet Protocol (IP) traffic and real time video

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 20

Technologies

bull 3G is superior to the other digital standards like-ndash GSM (Global System for Mobile) communications standard

used worldwide ndash And IS-136 TDMA standard used primarily in North America ndash IS-95 CDMA systems

bull 3G Technologies-

ndash WCDMA or UMTS-FDD (Universal Mobile Telecommunications System - Frequency Division Duplex)---Direct Spread

ndash CDMA2000 - 1x-EvDOEvDV---Multi carrier

ndash UMTS ndash TDD (Time Division Duplex) or TD-SCDMA (Time Division - Synchronous Code Division Multiple Access) ---Time Code

ndash CDMA2000 and WCDMA or UMTS-FDD have similar architectures

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 21

Evolution Paths

25G2G 3G

cdmaOneIS-95A

TDMA

cdmaOneIS-95B Cdma2000 1X

Cdma20001xEV-DV

Cdma20001xEV-DO

GSMGPRS

EDGE WCDMA

GSM Map Core Network

IS-41 Core Network

25G2G 3G

cdmaOneIS-95A

TDMA

cdmaOneIS-95B Cdma2000 1X

Cdma20001xEV-DV

Cdma20001xEV-DO

GSMGPRS

EDGE WCDMA

GSM Map Core Network

IS-41 Core Network

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 22

WCDMA

bull Spectrumndash 1920 MHz ndash 1980 MHz (uplink)ndash 2110 MHz ndash 2170 MHz (downlink)orndash 1850 MHz ndash 1910 MHz (uplink)ndash 1930 MHz ndash 1990 MHz (downlink)ndash Channel Spacing 5 Mhz

bull WCDMA is connected to the FDD Phy and the associated protocols Focus here

bull UTRAN-Universal Terrestrial Radio Access Network- is associated with the WCDMA radio Access Network

bull UMTS refers to the whole network

12 23

UMTS-FDD WCDMA

bull Wideband Direct Sequence Code Division Multiple Access

bull Does not assign a specific frequency to each user Instead every channel uses the full available spectrum

bull Individual conversations are encoded with a pseudo-random digital sequence

bull See httpwwwumtsworldcomtechnologyoverviewhtm

12 24

WCDMA Parameters

Channel BW 5 MHz

Forward RF Channel Structure Direct Spread

Chip Rate 384 Mcps

Frame Length 10 ms (38400 chips)

No of slotsframe 15

No of chipsslot 2560chips (Max 2560 bits)

Power Control Open and fast close loop (16 KHz)

Uplink Spreading Factor 4 to 256

Downlink Spreading Factor 4 to 512

12 25

Spreading Operation

bull Spreading means increasing the signal bandwidthbull Strictly speaking spreading includes two

operationsndash Channelisation (increases signal bandwidth) using

orthogonal codesndash Scrambling (does not affect the signal bandwidth) using

pseudo noise codes

12 26

Codes

Channellization Code Scrambling Code

Usage UL Separation of physical dataand control channels from same UEDL Separation of different userswithin one cell

UL Separation of terminalsDL Separation ofcellssectors

Length UL4-256 chipsDL4-512 chips

38400 chips

No of codes No of codes under one scrambling code= SF

UL Several millionDL 512

Code Family Orthogonal Variable Spreading Factor

Long 10ms code Gold codeShort code Extended S(2) code Family

Increase BW YES NO

12 27

UMTS Architecture

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

Cell site

Access Network

Core Network

User Equipment

12 28

UMTS Architecture

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 29

UMTS Architecture

bull User equipment-UEndash UMTS Subscriber Identity Module ndashUSIMndash Mobile Equipment- cell phone

bull UMTS Terrestrial Radio Access Networkndash Radio Network Subsystem

bull Node B- BSndash Transceiverndash Rate adaptationndash Radio resource managementndash Power control

12 30

UMTS Architecture

bull Radio Network Controller ndash RNCndash Radio access controlndash Connection controlndash Load congestion and admission controlndash Code allocation

ndash Core Networkbull MSCbull VLRbull HLRbull Gateway MSC ndash GMSC

ndash Supports circuit switched connectionsbull Serving GRPS Support Node ndash SGPRS

ndash Logical interface to UTRAN for packet transportraquo Session managementraquo Logical link management

bull Gateway GPRS Support Node ndash GGSNndash Supports packet switched transportndash This is an IP router

12 31

UMTS Protocol Architecture - User Plane

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

FP= Framing Protocol GTP-U= GPRS Tunneling Protocol-UserPDCP =Packet Data convergence Protocol

12 32

UMTS Protocol Stack

bull Radio Resource Control-RRC

bull Broadcastmulitcast control- BMC

bull Packet Data convergence Protocol- PDCPndash Header

compression

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

12 33

Packet SAR

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

12 34

Physical Layerbull The physical layer offers information transfer services to

the MAC layer These services are denoted as Transport channels (TrChrsquos) There are also Physical channels

bull Physical layer comprises following functionsndash 1048713 Various handover functionsndash 1048713 Error detection and report to higher layersndash 1048713 Multiplexing of transport channelsndash 1048713 Mapping of transport channels to physical channelsndash 1048713 Fast Close loop Power controlndash 1048713 Frequency and Time Synchronizationndash 1048713 Other responsibilities associated with transmitting and

receiving signals over the wireless mediandash Measurements

bull SIRbull Tx power Frame error rate etc

bull Physical channel is assigned a specific code

12 35

Transport amp Physical Channels

Transport Channel Physical Channel(ULDL) Dedicated Channel DCH Dedicated Physical Data Channel DPDCH

Dedicated Physical Control Channel DPCCH

(UL) Random Access Channel RACH Physical random access channel PRACH

(UL) Common packet channel CPCH Physical common packet channel PCPCH

(DL) Broadcast channel BCH Primary common control physical channel P-CCPCH

(DL) Forward access channel FACH(DL) Paging channel PCH

Secondary common control physical channel S-CCPCH

(DL) Downlink shared channel DSCH Physical downlink shared channel PDSCH

Signaling physical channels

Synchronization channel SCHCommon pilot channel CPICHAcquisition indication channel AICHPaging indication channel PICHCPCH Status indication channel CSICHCollision detectionChannel assignment indicator channel CDCA-ICH

12 36

UMTS FDD frame structure

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 37

MAC Layer

bull The MAC layer offers Data transfer to RLC and higher layers

bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically

bit rate within a predefined set per information unit delivered to the physical layer

ndash Service multiplexing on RACH FACH and dedicated channels

ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling

ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements

12 38

Physical Layer

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 39

RRC Layerbull The RRC layer offers the core network the following

servicesndash General control service which is used as an information

broadcast servicendash Notification service which is used for paging and

notification of a selected UEsndash Dedicated control service which is used for

establishmentrelease of a connection and transfer of messages using the connection

bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover

admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection

12 40

RLC Layer

bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is

appended to the information unit received from the higher layer

ndash Assured and un assured data transferbull The RLC layer comprises the following functions

ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the

WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the

control plane)ndash Duplicate detectionndash Flow controlndash Ciphering

12 41

RLC Layer-Modesbull Transparent-TM

ndash No header attachedndash SARndash SDU discard

bull Delete SDU if not sent before timer expiresndash Used for

bull Voicebull Some signaling

bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability

bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat

12 42

RLC Layer

From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the

UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

12 43

UE-Call states

bull Designed to ndash Take advantage of bursty nature of

datandash Save batter powerndash Maintains logical session and tracks

mobility but when appropriatendash releases dedicated resources to

increase overall capacityndash asleeps the UE

12 44

UE-Call states

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 45

UE-Call states

bull Idle modendash No active sessionndash UE monitors

Paging CHndash Sleeps between

paging cycles

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 46

UE-Call states

bull CELL_DCH state (Dedicated)ndash A dedicated physical

channel is allocated to the UE in uplink and downlink

ndash The UE is known on cell level according to its current active set

ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE

ndash Call typesbull Circuit Switched always in

this statebull Packet Switched in this

state if transferring large volume of data

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 47

UE-Call states

bull CELL_FACH state(Forward Access Ch)

ndash No dedicated physical channel is allocated to the UE

ndash The UE continuously monitors a FACH in the downlink

ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel

ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update

ndash Radio not put to sleepndash For packet switched sessions

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 48

UE-Call states

bull CELL_PCH state (Paging Ch)ndash No dedicated physical

channel is allocated to the UE

ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash Sleep between pagesndash A logical session is still upndash The position of the UE is

known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 49

UE-Call states

bull URA_PCH State ndash No dedicated channel is

allocated to the UEndash The UE selects a PCH with

the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state

ndash Similar to CELL_PCH state only the at the URA level

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 50

Power Control-PC

bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to

ensure that there is enough power for mobiles at the cell edge

bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control

commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command

ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break

12 51

Power Control

bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss

by means of a downlink beacon signalndash Provide a coarse initial power setting of

the mobile at the beginning of a connection

ndash Apply only prior to initiating the transmission on RACH or CPCH

12 52

Packet Access in WCDMA

bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection

bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared

bull RNC can decide when and how to send packets based on type of packet traffic

ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech

ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video

ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing

ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail

bull RNC can assign a packet to a specific channel

Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 53

Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the

downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft

handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts

bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts

bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink

orthogonal code is reserved according to maximum bit rate

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 54

Packet Access in WCDMA

bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner

bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer

bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate

bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and

bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 55

Packet Access in WCDMA

bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased

bull Advantagesndash resources are in full usage due to longer transmission

timendash small variation in interference levelndash longer uplink range due to lower bit rate

bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 56

Packet Access in WCDMA

bull Time division is normally used with shared channels and code division is normally used with dedicated channels

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 57

Packet Access in WCDMA

bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users

could be based on required transmission powerbull Users close to the BS requires less

transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate

bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput

bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 58

HSDPA amp Enhance Uplink

bull HSDPA = High Speed Downlink Packet Access

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 59

HSDPA amp Enhance Uplink

bull Remember it is better (more efficient) to have a large number of users sharing a single server

bull This lead to a desire to have fast allocation of shared resources

bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code

bull Uplink resourcesndash Interference at the BS

bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)

bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)

12 60

HSDPA amp Enhance Uplink

bull UTRAN Architecture with HSDPA and enhanced uplink

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 61

HSDPA amp Enhance Uplink

bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK

modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and

coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function

moved to Node-B (WCDMA packet scheduling was done in the RNC)

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 62

HSDPA amp Enhance Uplink

bull Gain in Performance

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 63

HSDPA

bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to

individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes

bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)

12 64

HSDPA

bull New frame structurendash Five subframesW-CDMA

framendash User data can be

assigned on a subframe basis

ndash System can adjust in 2ms

ndash Each subframe is a transmission time interval (TTI) = 2ms

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 65

HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared

resource is also in the time domain

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 66

HSDPA

bull Another view

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

Spreading Code

12 67

HSDPAbull Link Adaptation

ndash Remember the fast power control is commonly used to

bull Maintain constant EnergyNoise ratiobull Reduce effect of fading

ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant

EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 68

HSDPA

ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)

ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum

bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user

bull 1 ndash 2 Mbs closer to achievable under real conditions

12 69

HSDPA

bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE

bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms

bull CQI (0-30) each mapping into a modulation SF etc

bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression

bull

12 70

HSDPA

bull Schedulingndash The scheduler decides which user

should get access to each TTI ndash CQI provides input into a Scheduler

bull Proportional Fair (PF) Scheduler can be uses

bull Implementation Specific

12 71

HSDPA

bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number

of spreading codes limits rate not power so likely receive first transmission

ndash At greater distances move from BS see more errors IR will require additional transmission but not many

ndash HARQ only retransmit upon an ACK or NACK

12 72

HSDPA

From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007

12 73

HSDPA

bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2

ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent

Scheduling

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 18

3G- Advantages

3G phones promise - bull Improved digital voice communications bull Larger Bandwidth ndash Higher Data ratebull Greater subscriber capacity bull Fast packet-based data services like e-mail

short message service (SMS) and Internet access at broadband speeds

bull Most carriers also expect consumers to want - ndash location services ndash interactive gaming ndash streaming video ndash home monitoring and control ndash and who knows what else while being fully mobile

anywhere in the world

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 19

3G Capabilitiesbull Voice quality comparable to the public

switched telephone networkbull 144 Kbps- user in high-speed motor vehiclesbull 384 Kbps- pedestrians standing or moving

slowly over small areasbull Up to 2 Mbps- fixed applications like office usebull Symmetricalasymmetrical data transmission

ratesbull Support for both packet switched and circuit

switched data services like Internet Protocol (IP) traffic and real time video

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 20

Technologies

bull 3G is superior to the other digital standards like-ndash GSM (Global System for Mobile) communications standard

used worldwide ndash And IS-136 TDMA standard used primarily in North America ndash IS-95 CDMA systems

bull 3G Technologies-

ndash WCDMA or UMTS-FDD (Universal Mobile Telecommunications System - Frequency Division Duplex)---Direct Spread

ndash CDMA2000 - 1x-EvDOEvDV---Multi carrier

ndash UMTS ndash TDD (Time Division Duplex) or TD-SCDMA (Time Division - Synchronous Code Division Multiple Access) ---Time Code

ndash CDMA2000 and WCDMA or UMTS-FDD have similar architectures

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 21

Evolution Paths

25G2G 3G

cdmaOneIS-95A

TDMA

cdmaOneIS-95B Cdma2000 1X

Cdma20001xEV-DV

Cdma20001xEV-DO

GSMGPRS

EDGE WCDMA

GSM Map Core Network

IS-41 Core Network

25G2G 3G

cdmaOneIS-95A

TDMA

cdmaOneIS-95B Cdma2000 1X

Cdma20001xEV-DV

Cdma20001xEV-DO

GSMGPRS

EDGE WCDMA

GSM Map Core Network

IS-41 Core Network

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 22

WCDMA

bull Spectrumndash 1920 MHz ndash 1980 MHz (uplink)ndash 2110 MHz ndash 2170 MHz (downlink)orndash 1850 MHz ndash 1910 MHz (uplink)ndash 1930 MHz ndash 1990 MHz (downlink)ndash Channel Spacing 5 Mhz

bull WCDMA is connected to the FDD Phy and the associated protocols Focus here

bull UTRAN-Universal Terrestrial Radio Access Network- is associated with the WCDMA radio Access Network

bull UMTS refers to the whole network

12 23

UMTS-FDD WCDMA

bull Wideband Direct Sequence Code Division Multiple Access

bull Does not assign a specific frequency to each user Instead every channel uses the full available spectrum

bull Individual conversations are encoded with a pseudo-random digital sequence

bull See httpwwwumtsworldcomtechnologyoverviewhtm

12 24

WCDMA Parameters

Channel BW 5 MHz

Forward RF Channel Structure Direct Spread

Chip Rate 384 Mcps

Frame Length 10 ms (38400 chips)

No of slotsframe 15

No of chipsslot 2560chips (Max 2560 bits)

Power Control Open and fast close loop (16 KHz)

Uplink Spreading Factor 4 to 256

Downlink Spreading Factor 4 to 512

12 25

Spreading Operation

bull Spreading means increasing the signal bandwidthbull Strictly speaking spreading includes two

operationsndash Channelisation (increases signal bandwidth) using

orthogonal codesndash Scrambling (does not affect the signal bandwidth) using

pseudo noise codes

12 26

Codes

Channellization Code Scrambling Code

Usage UL Separation of physical dataand control channels from same UEDL Separation of different userswithin one cell

UL Separation of terminalsDL Separation ofcellssectors

Length UL4-256 chipsDL4-512 chips

38400 chips

No of codes No of codes under one scrambling code= SF

UL Several millionDL 512

Code Family Orthogonal Variable Spreading Factor

Long 10ms code Gold codeShort code Extended S(2) code Family

Increase BW YES NO

12 27

UMTS Architecture

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

Cell site

Access Network

Core Network

User Equipment

12 28

UMTS Architecture

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 29

UMTS Architecture

bull User equipment-UEndash UMTS Subscriber Identity Module ndashUSIMndash Mobile Equipment- cell phone

bull UMTS Terrestrial Radio Access Networkndash Radio Network Subsystem

bull Node B- BSndash Transceiverndash Rate adaptationndash Radio resource managementndash Power control

12 30

UMTS Architecture

bull Radio Network Controller ndash RNCndash Radio access controlndash Connection controlndash Load congestion and admission controlndash Code allocation

ndash Core Networkbull MSCbull VLRbull HLRbull Gateway MSC ndash GMSC

ndash Supports circuit switched connectionsbull Serving GRPS Support Node ndash SGPRS

ndash Logical interface to UTRAN for packet transportraquo Session managementraquo Logical link management

bull Gateway GPRS Support Node ndash GGSNndash Supports packet switched transportndash This is an IP router

12 31

UMTS Protocol Architecture - User Plane

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

FP= Framing Protocol GTP-U= GPRS Tunneling Protocol-UserPDCP =Packet Data convergence Protocol

12 32

UMTS Protocol Stack

bull Radio Resource Control-RRC

bull Broadcastmulitcast control- BMC

bull Packet Data convergence Protocol- PDCPndash Header

compression

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

12 33

Packet SAR

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

12 34

Physical Layerbull The physical layer offers information transfer services to

the MAC layer These services are denoted as Transport channels (TrChrsquos) There are also Physical channels

bull Physical layer comprises following functionsndash 1048713 Various handover functionsndash 1048713 Error detection and report to higher layersndash 1048713 Multiplexing of transport channelsndash 1048713 Mapping of transport channels to physical channelsndash 1048713 Fast Close loop Power controlndash 1048713 Frequency and Time Synchronizationndash 1048713 Other responsibilities associated with transmitting and

receiving signals over the wireless mediandash Measurements

bull SIRbull Tx power Frame error rate etc

bull Physical channel is assigned a specific code

12 35

Transport amp Physical Channels

Transport Channel Physical Channel(ULDL) Dedicated Channel DCH Dedicated Physical Data Channel DPDCH

Dedicated Physical Control Channel DPCCH

(UL) Random Access Channel RACH Physical random access channel PRACH

(UL) Common packet channel CPCH Physical common packet channel PCPCH

(DL) Broadcast channel BCH Primary common control physical channel P-CCPCH

(DL) Forward access channel FACH(DL) Paging channel PCH

Secondary common control physical channel S-CCPCH

(DL) Downlink shared channel DSCH Physical downlink shared channel PDSCH

Signaling physical channels

Synchronization channel SCHCommon pilot channel CPICHAcquisition indication channel AICHPaging indication channel PICHCPCH Status indication channel CSICHCollision detectionChannel assignment indicator channel CDCA-ICH

12 36

UMTS FDD frame structure

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 37

MAC Layer

bull The MAC layer offers Data transfer to RLC and higher layers

bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically

bit rate within a predefined set per information unit delivered to the physical layer

ndash Service multiplexing on RACH FACH and dedicated channels

ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling

ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements

12 38

Physical Layer

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 39

RRC Layerbull The RRC layer offers the core network the following

servicesndash General control service which is used as an information

broadcast servicendash Notification service which is used for paging and

notification of a selected UEsndash Dedicated control service which is used for

establishmentrelease of a connection and transfer of messages using the connection

bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover

admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection

12 40

RLC Layer

bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is

appended to the information unit received from the higher layer

ndash Assured and un assured data transferbull The RLC layer comprises the following functions

ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the

WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the

control plane)ndash Duplicate detectionndash Flow controlndash Ciphering

12 41

RLC Layer-Modesbull Transparent-TM

ndash No header attachedndash SARndash SDU discard

bull Delete SDU if not sent before timer expiresndash Used for

bull Voicebull Some signaling

bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability

bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat

12 42

RLC Layer

From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the

UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

12 43

UE-Call states

bull Designed to ndash Take advantage of bursty nature of

datandash Save batter powerndash Maintains logical session and tracks

mobility but when appropriatendash releases dedicated resources to

increase overall capacityndash asleeps the UE

12 44

UE-Call states

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 45

UE-Call states

bull Idle modendash No active sessionndash UE monitors

Paging CHndash Sleeps between

paging cycles

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 46

UE-Call states

bull CELL_DCH state (Dedicated)ndash A dedicated physical

channel is allocated to the UE in uplink and downlink

ndash The UE is known on cell level according to its current active set

ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE

ndash Call typesbull Circuit Switched always in

this statebull Packet Switched in this

state if transferring large volume of data

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 47

UE-Call states

bull CELL_FACH state(Forward Access Ch)

ndash No dedicated physical channel is allocated to the UE

ndash The UE continuously monitors a FACH in the downlink

ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel

ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update

ndash Radio not put to sleepndash For packet switched sessions

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 48

UE-Call states

bull CELL_PCH state (Paging Ch)ndash No dedicated physical

channel is allocated to the UE

ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash Sleep between pagesndash A logical session is still upndash The position of the UE is

known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 49

UE-Call states

bull URA_PCH State ndash No dedicated channel is

allocated to the UEndash The UE selects a PCH with

the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state

ndash Similar to CELL_PCH state only the at the URA level

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 50

Power Control-PC

bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to

ensure that there is enough power for mobiles at the cell edge

bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control

commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command

ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break

12 51

Power Control

bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss

by means of a downlink beacon signalndash Provide a coarse initial power setting of

the mobile at the beginning of a connection

ndash Apply only prior to initiating the transmission on RACH or CPCH

12 52

Packet Access in WCDMA

bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection

bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared

bull RNC can decide when and how to send packets based on type of packet traffic

ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech

ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video

ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing

ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail

bull RNC can assign a packet to a specific channel

Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 53

Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the

downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft

handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts

bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts

bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink

orthogonal code is reserved according to maximum bit rate

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 54

Packet Access in WCDMA

bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner

bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer

bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate

bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and

bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 55

Packet Access in WCDMA

bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased

bull Advantagesndash resources are in full usage due to longer transmission

timendash small variation in interference levelndash longer uplink range due to lower bit rate

bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 56

Packet Access in WCDMA

bull Time division is normally used with shared channels and code division is normally used with dedicated channels

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 57

Packet Access in WCDMA

bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users

could be based on required transmission powerbull Users close to the BS requires less

transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate

bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput

bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 58

HSDPA amp Enhance Uplink

bull HSDPA = High Speed Downlink Packet Access

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 59

HSDPA amp Enhance Uplink

bull Remember it is better (more efficient) to have a large number of users sharing a single server

bull This lead to a desire to have fast allocation of shared resources

bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code

bull Uplink resourcesndash Interference at the BS

bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)

bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)

12 60

HSDPA amp Enhance Uplink

bull UTRAN Architecture with HSDPA and enhanced uplink

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 61

HSDPA amp Enhance Uplink

bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK

modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and

coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function

moved to Node-B (WCDMA packet scheduling was done in the RNC)

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 62

HSDPA amp Enhance Uplink

bull Gain in Performance

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 63

HSDPA

bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to

individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes

bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)

12 64

HSDPA

bull New frame structurendash Five subframesW-CDMA

framendash User data can be

assigned on a subframe basis

ndash System can adjust in 2ms

ndash Each subframe is a transmission time interval (TTI) = 2ms

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 65

HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared

resource is also in the time domain

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 66

HSDPA

bull Another view

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

Spreading Code

12 67

HSDPAbull Link Adaptation

ndash Remember the fast power control is commonly used to

bull Maintain constant EnergyNoise ratiobull Reduce effect of fading

ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant

EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 68

HSDPA

ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)

ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum

bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user

bull 1 ndash 2 Mbs closer to achievable under real conditions

12 69

HSDPA

bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE

bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms

bull CQI (0-30) each mapping into a modulation SF etc

bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression

bull

12 70

HSDPA

bull Schedulingndash The scheduler decides which user

should get access to each TTI ndash CQI provides input into a Scheduler

bull Proportional Fair (PF) Scheduler can be uses

bull Implementation Specific

12 71

HSDPA

bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number

of spreading codes limits rate not power so likely receive first transmission

ndash At greater distances move from BS see more errors IR will require additional transmission but not many

ndash HARQ only retransmit upon an ACK or NACK

12 72

HSDPA

From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007

12 73

HSDPA

bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2

ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent

Scheduling

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 19

3G Capabilitiesbull Voice quality comparable to the public

switched telephone networkbull 144 Kbps- user in high-speed motor vehiclesbull 384 Kbps- pedestrians standing or moving

slowly over small areasbull Up to 2 Mbps- fixed applications like office usebull Symmetricalasymmetrical data transmission

ratesbull Support for both packet switched and circuit

switched data services like Internet Protocol (IP) traffic and real time video

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 20

Technologies

bull 3G is superior to the other digital standards like-ndash GSM (Global System for Mobile) communications standard

used worldwide ndash And IS-136 TDMA standard used primarily in North America ndash IS-95 CDMA systems

bull 3G Technologies-

ndash WCDMA or UMTS-FDD (Universal Mobile Telecommunications System - Frequency Division Duplex)---Direct Spread

ndash CDMA2000 - 1x-EvDOEvDV---Multi carrier

ndash UMTS ndash TDD (Time Division Duplex) or TD-SCDMA (Time Division - Synchronous Code Division Multiple Access) ---Time Code

ndash CDMA2000 and WCDMA or UMTS-FDD have similar architectures

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 21

Evolution Paths

25G2G 3G

cdmaOneIS-95A

TDMA

cdmaOneIS-95B Cdma2000 1X

Cdma20001xEV-DV

Cdma20001xEV-DO

GSMGPRS

EDGE WCDMA

GSM Map Core Network

IS-41 Core Network

25G2G 3G

cdmaOneIS-95A

TDMA

cdmaOneIS-95B Cdma2000 1X

Cdma20001xEV-DV

Cdma20001xEV-DO

GSMGPRS

EDGE WCDMA

GSM Map Core Network

IS-41 Core Network

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 22

WCDMA

bull Spectrumndash 1920 MHz ndash 1980 MHz (uplink)ndash 2110 MHz ndash 2170 MHz (downlink)orndash 1850 MHz ndash 1910 MHz (uplink)ndash 1930 MHz ndash 1990 MHz (downlink)ndash Channel Spacing 5 Mhz

bull WCDMA is connected to the FDD Phy and the associated protocols Focus here

bull UTRAN-Universal Terrestrial Radio Access Network- is associated with the WCDMA radio Access Network

bull UMTS refers to the whole network

12 23

UMTS-FDD WCDMA

bull Wideband Direct Sequence Code Division Multiple Access

bull Does not assign a specific frequency to each user Instead every channel uses the full available spectrum

bull Individual conversations are encoded with a pseudo-random digital sequence

bull See httpwwwumtsworldcomtechnologyoverviewhtm

12 24

WCDMA Parameters

Channel BW 5 MHz

Forward RF Channel Structure Direct Spread

Chip Rate 384 Mcps

Frame Length 10 ms (38400 chips)

No of slotsframe 15

No of chipsslot 2560chips (Max 2560 bits)

Power Control Open and fast close loop (16 KHz)

Uplink Spreading Factor 4 to 256

Downlink Spreading Factor 4 to 512

12 25

Spreading Operation

bull Spreading means increasing the signal bandwidthbull Strictly speaking spreading includes two

operationsndash Channelisation (increases signal bandwidth) using

orthogonal codesndash Scrambling (does not affect the signal bandwidth) using

pseudo noise codes

12 26

Codes

Channellization Code Scrambling Code

Usage UL Separation of physical dataand control channels from same UEDL Separation of different userswithin one cell

UL Separation of terminalsDL Separation ofcellssectors

Length UL4-256 chipsDL4-512 chips

38400 chips

No of codes No of codes under one scrambling code= SF

UL Several millionDL 512

Code Family Orthogonal Variable Spreading Factor

Long 10ms code Gold codeShort code Extended S(2) code Family

Increase BW YES NO

12 27

UMTS Architecture

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

Cell site

Access Network

Core Network

User Equipment

12 28

UMTS Architecture

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 29

UMTS Architecture

bull User equipment-UEndash UMTS Subscriber Identity Module ndashUSIMndash Mobile Equipment- cell phone

bull UMTS Terrestrial Radio Access Networkndash Radio Network Subsystem

bull Node B- BSndash Transceiverndash Rate adaptationndash Radio resource managementndash Power control

12 30

UMTS Architecture

bull Radio Network Controller ndash RNCndash Radio access controlndash Connection controlndash Load congestion and admission controlndash Code allocation

ndash Core Networkbull MSCbull VLRbull HLRbull Gateway MSC ndash GMSC

ndash Supports circuit switched connectionsbull Serving GRPS Support Node ndash SGPRS

ndash Logical interface to UTRAN for packet transportraquo Session managementraquo Logical link management

bull Gateway GPRS Support Node ndash GGSNndash Supports packet switched transportndash This is an IP router

12 31

UMTS Protocol Architecture - User Plane

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

FP= Framing Protocol GTP-U= GPRS Tunneling Protocol-UserPDCP =Packet Data convergence Protocol

12 32

UMTS Protocol Stack

bull Radio Resource Control-RRC

bull Broadcastmulitcast control- BMC

bull Packet Data convergence Protocol- PDCPndash Header

compression

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

12 33

Packet SAR

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

12 34

Physical Layerbull The physical layer offers information transfer services to

the MAC layer These services are denoted as Transport channels (TrChrsquos) There are also Physical channels

bull Physical layer comprises following functionsndash 1048713 Various handover functionsndash 1048713 Error detection and report to higher layersndash 1048713 Multiplexing of transport channelsndash 1048713 Mapping of transport channels to physical channelsndash 1048713 Fast Close loop Power controlndash 1048713 Frequency and Time Synchronizationndash 1048713 Other responsibilities associated with transmitting and

receiving signals over the wireless mediandash Measurements

bull SIRbull Tx power Frame error rate etc

bull Physical channel is assigned a specific code

12 35

Transport amp Physical Channels

Transport Channel Physical Channel(ULDL) Dedicated Channel DCH Dedicated Physical Data Channel DPDCH

Dedicated Physical Control Channel DPCCH

(UL) Random Access Channel RACH Physical random access channel PRACH

(UL) Common packet channel CPCH Physical common packet channel PCPCH

(DL) Broadcast channel BCH Primary common control physical channel P-CCPCH

(DL) Forward access channel FACH(DL) Paging channel PCH

Secondary common control physical channel S-CCPCH

(DL) Downlink shared channel DSCH Physical downlink shared channel PDSCH

Signaling physical channels

Synchronization channel SCHCommon pilot channel CPICHAcquisition indication channel AICHPaging indication channel PICHCPCH Status indication channel CSICHCollision detectionChannel assignment indicator channel CDCA-ICH

12 36

UMTS FDD frame structure

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 37

MAC Layer

bull The MAC layer offers Data transfer to RLC and higher layers

bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically

bit rate within a predefined set per information unit delivered to the physical layer

ndash Service multiplexing on RACH FACH and dedicated channels

ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling

ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements

12 38

Physical Layer

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 39

RRC Layerbull The RRC layer offers the core network the following

servicesndash General control service which is used as an information

broadcast servicendash Notification service which is used for paging and

notification of a selected UEsndash Dedicated control service which is used for

establishmentrelease of a connection and transfer of messages using the connection

bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover

admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection

12 40

RLC Layer

bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is

appended to the information unit received from the higher layer

ndash Assured and un assured data transferbull The RLC layer comprises the following functions

ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the

WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the

control plane)ndash Duplicate detectionndash Flow controlndash Ciphering

12 41

RLC Layer-Modesbull Transparent-TM

ndash No header attachedndash SARndash SDU discard

bull Delete SDU if not sent before timer expiresndash Used for

bull Voicebull Some signaling

bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability

bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat

12 42

RLC Layer

From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the

UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

12 43

UE-Call states

bull Designed to ndash Take advantage of bursty nature of

datandash Save batter powerndash Maintains logical session and tracks

mobility but when appropriatendash releases dedicated resources to

increase overall capacityndash asleeps the UE

12 44

UE-Call states

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 45

UE-Call states

bull Idle modendash No active sessionndash UE monitors

Paging CHndash Sleeps between

paging cycles

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 46

UE-Call states

bull CELL_DCH state (Dedicated)ndash A dedicated physical

channel is allocated to the UE in uplink and downlink

ndash The UE is known on cell level according to its current active set

ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE

ndash Call typesbull Circuit Switched always in

this statebull Packet Switched in this

state if transferring large volume of data

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 47

UE-Call states

bull CELL_FACH state(Forward Access Ch)

ndash No dedicated physical channel is allocated to the UE

ndash The UE continuously monitors a FACH in the downlink

ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel

ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update

ndash Radio not put to sleepndash For packet switched sessions

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 48

UE-Call states

bull CELL_PCH state (Paging Ch)ndash No dedicated physical

channel is allocated to the UE

ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash Sleep between pagesndash A logical session is still upndash The position of the UE is

known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 49

UE-Call states

bull URA_PCH State ndash No dedicated channel is

allocated to the UEndash The UE selects a PCH with

the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state

ndash Similar to CELL_PCH state only the at the URA level

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 50

Power Control-PC

bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to

ensure that there is enough power for mobiles at the cell edge

bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control

commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command

ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break

12 51

Power Control

bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss

by means of a downlink beacon signalndash Provide a coarse initial power setting of

the mobile at the beginning of a connection

ndash Apply only prior to initiating the transmission on RACH or CPCH

12 52

Packet Access in WCDMA

bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection

bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared

bull RNC can decide when and how to send packets based on type of packet traffic

ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech

ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video

ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing

ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail

bull RNC can assign a packet to a specific channel

Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 53

Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the

downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft

handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts

bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts

bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink

orthogonal code is reserved according to maximum bit rate

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 54

Packet Access in WCDMA

bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner

bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer

bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate

bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and

bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 55

Packet Access in WCDMA

bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased

bull Advantagesndash resources are in full usage due to longer transmission

timendash small variation in interference levelndash longer uplink range due to lower bit rate

bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 56

Packet Access in WCDMA

bull Time division is normally used with shared channels and code division is normally used with dedicated channels

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 57

Packet Access in WCDMA

bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users

could be based on required transmission powerbull Users close to the BS requires less

transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate

bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput

bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 58

HSDPA amp Enhance Uplink

bull HSDPA = High Speed Downlink Packet Access

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 59

HSDPA amp Enhance Uplink

bull Remember it is better (more efficient) to have a large number of users sharing a single server

bull This lead to a desire to have fast allocation of shared resources

bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code

bull Uplink resourcesndash Interference at the BS

bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)

bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)

12 60

HSDPA amp Enhance Uplink

bull UTRAN Architecture with HSDPA and enhanced uplink

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 61

HSDPA amp Enhance Uplink

bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK

modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and

coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function

moved to Node-B (WCDMA packet scheduling was done in the RNC)

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 62

HSDPA amp Enhance Uplink

bull Gain in Performance

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 63

HSDPA

bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to

individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes

bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)

12 64

HSDPA

bull New frame structurendash Five subframesW-CDMA

framendash User data can be

assigned on a subframe basis

ndash System can adjust in 2ms

ndash Each subframe is a transmission time interval (TTI) = 2ms

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 65

HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared

resource is also in the time domain

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 66

HSDPA

bull Another view

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

Spreading Code

12 67

HSDPAbull Link Adaptation

ndash Remember the fast power control is commonly used to

bull Maintain constant EnergyNoise ratiobull Reduce effect of fading

ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant

EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 68

HSDPA

ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)

ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum

bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user

bull 1 ndash 2 Mbs closer to achievable under real conditions

12 69

HSDPA

bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE

bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms

bull CQI (0-30) each mapping into a modulation SF etc

bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression

bull

12 70

HSDPA

bull Schedulingndash The scheduler decides which user

should get access to each TTI ndash CQI provides input into a Scheduler

bull Proportional Fair (PF) Scheduler can be uses

bull Implementation Specific

12 71

HSDPA

bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number

of spreading codes limits rate not power so likely receive first transmission

ndash At greater distances move from BS see more errors IR will require additional transmission but not many

ndash HARQ only retransmit upon an ACK or NACK

12 72

HSDPA

From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007

12 73

HSDPA

bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2

ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent

Scheduling

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 20

Technologies

bull 3G is superior to the other digital standards like-ndash GSM (Global System for Mobile) communications standard

used worldwide ndash And IS-136 TDMA standard used primarily in North America ndash IS-95 CDMA systems

bull 3G Technologies-

ndash WCDMA or UMTS-FDD (Universal Mobile Telecommunications System - Frequency Division Duplex)---Direct Spread

ndash CDMA2000 - 1x-EvDOEvDV---Multi carrier

ndash UMTS ndash TDD (Time Division Duplex) or TD-SCDMA (Time Division - Synchronous Code Division Multiple Access) ---Time Code

ndash CDMA2000 and WCDMA or UMTS-FDD have similar architectures

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 21

Evolution Paths

25G2G 3G

cdmaOneIS-95A

TDMA

cdmaOneIS-95B Cdma2000 1X

Cdma20001xEV-DV

Cdma20001xEV-DO

GSMGPRS

EDGE WCDMA

GSM Map Core Network

IS-41 Core Network

25G2G 3G

cdmaOneIS-95A

TDMA

cdmaOneIS-95B Cdma2000 1X

Cdma20001xEV-DV

Cdma20001xEV-DO

GSMGPRS

EDGE WCDMA

GSM Map Core Network

IS-41 Core Network

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 22

WCDMA

bull Spectrumndash 1920 MHz ndash 1980 MHz (uplink)ndash 2110 MHz ndash 2170 MHz (downlink)orndash 1850 MHz ndash 1910 MHz (uplink)ndash 1930 MHz ndash 1990 MHz (downlink)ndash Channel Spacing 5 Mhz

bull WCDMA is connected to the FDD Phy and the associated protocols Focus here

bull UTRAN-Universal Terrestrial Radio Access Network- is associated with the WCDMA radio Access Network

bull UMTS refers to the whole network

12 23

UMTS-FDD WCDMA

bull Wideband Direct Sequence Code Division Multiple Access

bull Does not assign a specific frequency to each user Instead every channel uses the full available spectrum

bull Individual conversations are encoded with a pseudo-random digital sequence

bull See httpwwwumtsworldcomtechnologyoverviewhtm

12 24

WCDMA Parameters

Channel BW 5 MHz

Forward RF Channel Structure Direct Spread

Chip Rate 384 Mcps

Frame Length 10 ms (38400 chips)

No of slotsframe 15

No of chipsslot 2560chips (Max 2560 bits)

Power Control Open and fast close loop (16 KHz)

Uplink Spreading Factor 4 to 256

Downlink Spreading Factor 4 to 512

12 25

Spreading Operation

bull Spreading means increasing the signal bandwidthbull Strictly speaking spreading includes two

operationsndash Channelisation (increases signal bandwidth) using

orthogonal codesndash Scrambling (does not affect the signal bandwidth) using

pseudo noise codes

12 26

Codes

Channellization Code Scrambling Code

Usage UL Separation of physical dataand control channels from same UEDL Separation of different userswithin one cell

UL Separation of terminalsDL Separation ofcellssectors

Length UL4-256 chipsDL4-512 chips

38400 chips

No of codes No of codes under one scrambling code= SF

UL Several millionDL 512

Code Family Orthogonal Variable Spreading Factor

Long 10ms code Gold codeShort code Extended S(2) code Family

Increase BW YES NO

12 27

UMTS Architecture

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

Cell site

Access Network

Core Network

User Equipment

12 28

UMTS Architecture

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 29

UMTS Architecture

bull User equipment-UEndash UMTS Subscriber Identity Module ndashUSIMndash Mobile Equipment- cell phone

bull UMTS Terrestrial Radio Access Networkndash Radio Network Subsystem

bull Node B- BSndash Transceiverndash Rate adaptationndash Radio resource managementndash Power control

12 30

UMTS Architecture

bull Radio Network Controller ndash RNCndash Radio access controlndash Connection controlndash Load congestion and admission controlndash Code allocation

ndash Core Networkbull MSCbull VLRbull HLRbull Gateway MSC ndash GMSC

ndash Supports circuit switched connectionsbull Serving GRPS Support Node ndash SGPRS

ndash Logical interface to UTRAN for packet transportraquo Session managementraquo Logical link management

bull Gateway GPRS Support Node ndash GGSNndash Supports packet switched transportndash This is an IP router

12 31

UMTS Protocol Architecture - User Plane

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

FP= Framing Protocol GTP-U= GPRS Tunneling Protocol-UserPDCP =Packet Data convergence Protocol

12 32

UMTS Protocol Stack

bull Radio Resource Control-RRC

bull Broadcastmulitcast control- BMC

bull Packet Data convergence Protocol- PDCPndash Header

compression

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

12 33

Packet SAR

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

12 34

Physical Layerbull The physical layer offers information transfer services to

the MAC layer These services are denoted as Transport channels (TrChrsquos) There are also Physical channels

bull Physical layer comprises following functionsndash 1048713 Various handover functionsndash 1048713 Error detection and report to higher layersndash 1048713 Multiplexing of transport channelsndash 1048713 Mapping of transport channels to physical channelsndash 1048713 Fast Close loop Power controlndash 1048713 Frequency and Time Synchronizationndash 1048713 Other responsibilities associated with transmitting and

receiving signals over the wireless mediandash Measurements

bull SIRbull Tx power Frame error rate etc

bull Physical channel is assigned a specific code

12 35

Transport amp Physical Channels

Transport Channel Physical Channel(ULDL) Dedicated Channel DCH Dedicated Physical Data Channel DPDCH

Dedicated Physical Control Channel DPCCH

(UL) Random Access Channel RACH Physical random access channel PRACH

(UL) Common packet channel CPCH Physical common packet channel PCPCH

(DL) Broadcast channel BCH Primary common control physical channel P-CCPCH

(DL) Forward access channel FACH(DL) Paging channel PCH

Secondary common control physical channel S-CCPCH

(DL) Downlink shared channel DSCH Physical downlink shared channel PDSCH

Signaling physical channels

Synchronization channel SCHCommon pilot channel CPICHAcquisition indication channel AICHPaging indication channel PICHCPCH Status indication channel CSICHCollision detectionChannel assignment indicator channel CDCA-ICH

12 36

UMTS FDD frame structure

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 37

MAC Layer

bull The MAC layer offers Data transfer to RLC and higher layers

bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically

bit rate within a predefined set per information unit delivered to the physical layer

ndash Service multiplexing on RACH FACH and dedicated channels

ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling

ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements

12 38

Physical Layer

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 39

RRC Layerbull The RRC layer offers the core network the following

servicesndash General control service which is used as an information

broadcast servicendash Notification service which is used for paging and

notification of a selected UEsndash Dedicated control service which is used for

establishmentrelease of a connection and transfer of messages using the connection

bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover

admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection

12 40

RLC Layer

bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is

appended to the information unit received from the higher layer

ndash Assured and un assured data transferbull The RLC layer comprises the following functions

ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the

WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the

control plane)ndash Duplicate detectionndash Flow controlndash Ciphering

12 41

RLC Layer-Modesbull Transparent-TM

ndash No header attachedndash SARndash SDU discard

bull Delete SDU if not sent before timer expiresndash Used for

bull Voicebull Some signaling

bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability

bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat

12 42

RLC Layer

From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the

UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

12 43

UE-Call states

bull Designed to ndash Take advantage of bursty nature of

datandash Save batter powerndash Maintains logical session and tracks

mobility but when appropriatendash releases dedicated resources to

increase overall capacityndash asleeps the UE

12 44

UE-Call states

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 45

UE-Call states

bull Idle modendash No active sessionndash UE monitors

Paging CHndash Sleeps between

paging cycles

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 46

UE-Call states

bull CELL_DCH state (Dedicated)ndash A dedicated physical

channel is allocated to the UE in uplink and downlink

ndash The UE is known on cell level according to its current active set

ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE

ndash Call typesbull Circuit Switched always in

this statebull Packet Switched in this

state if transferring large volume of data

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 47

UE-Call states

bull CELL_FACH state(Forward Access Ch)

ndash No dedicated physical channel is allocated to the UE

ndash The UE continuously monitors a FACH in the downlink

ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel

ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update

ndash Radio not put to sleepndash For packet switched sessions

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 48

UE-Call states

bull CELL_PCH state (Paging Ch)ndash No dedicated physical

channel is allocated to the UE

ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash Sleep between pagesndash A logical session is still upndash The position of the UE is

known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 49

UE-Call states

bull URA_PCH State ndash No dedicated channel is

allocated to the UEndash The UE selects a PCH with

the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state

ndash Similar to CELL_PCH state only the at the URA level

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 50

Power Control-PC

bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to

ensure that there is enough power for mobiles at the cell edge

bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control

commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command

ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break

12 51

Power Control

bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss

by means of a downlink beacon signalndash Provide a coarse initial power setting of

the mobile at the beginning of a connection

ndash Apply only prior to initiating the transmission on RACH or CPCH

12 52

Packet Access in WCDMA

bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection

bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared

bull RNC can decide when and how to send packets based on type of packet traffic

ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech

ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video

ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing

ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail

bull RNC can assign a packet to a specific channel

Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 53

Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the

downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft

handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts

bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts

bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink

orthogonal code is reserved according to maximum bit rate

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 54

Packet Access in WCDMA

bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner

bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer

bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate

bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and

bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 55

Packet Access in WCDMA

bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased

bull Advantagesndash resources are in full usage due to longer transmission

timendash small variation in interference levelndash longer uplink range due to lower bit rate

bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 56

Packet Access in WCDMA

bull Time division is normally used with shared channels and code division is normally used with dedicated channels

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 57

Packet Access in WCDMA

bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users

could be based on required transmission powerbull Users close to the BS requires less

transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate

bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput

bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 58

HSDPA amp Enhance Uplink

bull HSDPA = High Speed Downlink Packet Access

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 59

HSDPA amp Enhance Uplink

bull Remember it is better (more efficient) to have a large number of users sharing a single server

bull This lead to a desire to have fast allocation of shared resources

bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code

bull Uplink resourcesndash Interference at the BS

bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)

bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)

12 60

HSDPA amp Enhance Uplink

bull UTRAN Architecture with HSDPA and enhanced uplink

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 61

HSDPA amp Enhance Uplink

bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK

modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and

coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function

moved to Node-B (WCDMA packet scheduling was done in the RNC)

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 62

HSDPA amp Enhance Uplink

bull Gain in Performance

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 63

HSDPA

bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to

individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes

bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)

12 64

HSDPA

bull New frame structurendash Five subframesW-CDMA

framendash User data can be

assigned on a subframe basis

ndash System can adjust in 2ms

ndash Each subframe is a transmission time interval (TTI) = 2ms

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 65

HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared

resource is also in the time domain

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 66

HSDPA

bull Another view

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

Spreading Code

12 67

HSDPAbull Link Adaptation

ndash Remember the fast power control is commonly used to

bull Maintain constant EnergyNoise ratiobull Reduce effect of fading

ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant

EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 68

HSDPA

ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)

ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum

bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user

bull 1 ndash 2 Mbs closer to achievable under real conditions

12 69

HSDPA

bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE

bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms

bull CQI (0-30) each mapping into a modulation SF etc

bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression

bull

12 70

HSDPA

bull Schedulingndash The scheduler decides which user

should get access to each TTI ndash CQI provides input into a Scheduler

bull Proportional Fair (PF) Scheduler can be uses

bull Implementation Specific

12 71

HSDPA

bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number

of spreading codes limits rate not power so likely receive first transmission

ndash At greater distances move from BS see more errors IR will require additional transmission but not many

ndash HARQ only retransmit upon an ACK or NACK

12 72

HSDPA

From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007

12 73

HSDPA

bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2

ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent

Scheduling

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 21

Evolution Paths

25G2G 3G

cdmaOneIS-95A

TDMA

cdmaOneIS-95B Cdma2000 1X

Cdma20001xEV-DV

Cdma20001xEV-DO

GSMGPRS

EDGE WCDMA

GSM Map Core Network

IS-41 Core Network

25G2G 3G

cdmaOneIS-95A

TDMA

cdmaOneIS-95B Cdma2000 1X

Cdma20001xEV-DV

Cdma20001xEV-DO

GSMGPRS

EDGE WCDMA

GSM Map Core Network

IS-41 Core Network

Modified from wwwccsneueduhomerrajG250ProjectsNachiketMehtappt

12 22

WCDMA

bull Spectrumndash 1920 MHz ndash 1980 MHz (uplink)ndash 2110 MHz ndash 2170 MHz (downlink)orndash 1850 MHz ndash 1910 MHz (uplink)ndash 1930 MHz ndash 1990 MHz (downlink)ndash Channel Spacing 5 Mhz

bull WCDMA is connected to the FDD Phy and the associated protocols Focus here

bull UTRAN-Universal Terrestrial Radio Access Network- is associated with the WCDMA radio Access Network

bull UMTS refers to the whole network

12 23

UMTS-FDD WCDMA

bull Wideband Direct Sequence Code Division Multiple Access

bull Does not assign a specific frequency to each user Instead every channel uses the full available spectrum

bull Individual conversations are encoded with a pseudo-random digital sequence

bull See httpwwwumtsworldcomtechnologyoverviewhtm

12 24

WCDMA Parameters

Channel BW 5 MHz

Forward RF Channel Structure Direct Spread

Chip Rate 384 Mcps

Frame Length 10 ms (38400 chips)

No of slotsframe 15

No of chipsslot 2560chips (Max 2560 bits)

Power Control Open and fast close loop (16 KHz)

Uplink Spreading Factor 4 to 256

Downlink Spreading Factor 4 to 512

12 25

Spreading Operation

bull Spreading means increasing the signal bandwidthbull Strictly speaking spreading includes two

operationsndash Channelisation (increases signal bandwidth) using

orthogonal codesndash Scrambling (does not affect the signal bandwidth) using

pseudo noise codes

12 26

Codes

Channellization Code Scrambling Code

Usage UL Separation of physical dataand control channels from same UEDL Separation of different userswithin one cell

UL Separation of terminalsDL Separation ofcellssectors

Length UL4-256 chipsDL4-512 chips

38400 chips

No of codes No of codes under one scrambling code= SF

UL Several millionDL 512

Code Family Orthogonal Variable Spreading Factor

Long 10ms code Gold codeShort code Extended S(2) code Family

Increase BW YES NO

12 27

UMTS Architecture

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

Cell site

Access Network

Core Network

User Equipment

12 28

UMTS Architecture

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 29

UMTS Architecture

bull User equipment-UEndash UMTS Subscriber Identity Module ndashUSIMndash Mobile Equipment- cell phone

bull UMTS Terrestrial Radio Access Networkndash Radio Network Subsystem

bull Node B- BSndash Transceiverndash Rate adaptationndash Radio resource managementndash Power control

12 30

UMTS Architecture

bull Radio Network Controller ndash RNCndash Radio access controlndash Connection controlndash Load congestion and admission controlndash Code allocation

ndash Core Networkbull MSCbull VLRbull HLRbull Gateway MSC ndash GMSC

ndash Supports circuit switched connectionsbull Serving GRPS Support Node ndash SGPRS

ndash Logical interface to UTRAN for packet transportraquo Session managementraquo Logical link management

bull Gateway GPRS Support Node ndash GGSNndash Supports packet switched transportndash This is an IP router

12 31

UMTS Protocol Architecture - User Plane

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

FP= Framing Protocol GTP-U= GPRS Tunneling Protocol-UserPDCP =Packet Data convergence Protocol

12 32

UMTS Protocol Stack

bull Radio Resource Control-RRC

bull Broadcastmulitcast control- BMC

bull Packet Data convergence Protocol- PDCPndash Header

compression

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

12 33

Packet SAR

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

12 34

Physical Layerbull The physical layer offers information transfer services to

the MAC layer These services are denoted as Transport channels (TrChrsquos) There are also Physical channels

bull Physical layer comprises following functionsndash 1048713 Various handover functionsndash 1048713 Error detection and report to higher layersndash 1048713 Multiplexing of transport channelsndash 1048713 Mapping of transport channels to physical channelsndash 1048713 Fast Close loop Power controlndash 1048713 Frequency and Time Synchronizationndash 1048713 Other responsibilities associated with transmitting and

receiving signals over the wireless mediandash Measurements

bull SIRbull Tx power Frame error rate etc

bull Physical channel is assigned a specific code

12 35

Transport amp Physical Channels

Transport Channel Physical Channel(ULDL) Dedicated Channel DCH Dedicated Physical Data Channel DPDCH

Dedicated Physical Control Channel DPCCH

(UL) Random Access Channel RACH Physical random access channel PRACH

(UL) Common packet channel CPCH Physical common packet channel PCPCH

(DL) Broadcast channel BCH Primary common control physical channel P-CCPCH

(DL) Forward access channel FACH(DL) Paging channel PCH

Secondary common control physical channel S-CCPCH

(DL) Downlink shared channel DSCH Physical downlink shared channel PDSCH

Signaling physical channels

Synchronization channel SCHCommon pilot channel CPICHAcquisition indication channel AICHPaging indication channel PICHCPCH Status indication channel CSICHCollision detectionChannel assignment indicator channel CDCA-ICH

12 36

UMTS FDD frame structure

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 37

MAC Layer

bull The MAC layer offers Data transfer to RLC and higher layers

bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically

bit rate within a predefined set per information unit delivered to the physical layer

ndash Service multiplexing on RACH FACH and dedicated channels

ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling

ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements

12 38

Physical Layer

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 39

RRC Layerbull The RRC layer offers the core network the following

servicesndash General control service which is used as an information

broadcast servicendash Notification service which is used for paging and

notification of a selected UEsndash Dedicated control service which is used for

establishmentrelease of a connection and transfer of messages using the connection

bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover

admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection

12 40

RLC Layer

bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is

appended to the information unit received from the higher layer

ndash Assured and un assured data transferbull The RLC layer comprises the following functions

ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the

WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the

control plane)ndash Duplicate detectionndash Flow controlndash Ciphering

12 41

RLC Layer-Modesbull Transparent-TM

ndash No header attachedndash SARndash SDU discard

bull Delete SDU if not sent before timer expiresndash Used for

bull Voicebull Some signaling

bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability

bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat

12 42

RLC Layer

From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the

UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

12 43

UE-Call states

bull Designed to ndash Take advantage of bursty nature of

datandash Save batter powerndash Maintains logical session and tracks

mobility but when appropriatendash releases dedicated resources to

increase overall capacityndash asleeps the UE

12 44

UE-Call states

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 45

UE-Call states

bull Idle modendash No active sessionndash UE monitors

Paging CHndash Sleeps between

paging cycles

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 46

UE-Call states

bull CELL_DCH state (Dedicated)ndash A dedicated physical

channel is allocated to the UE in uplink and downlink

ndash The UE is known on cell level according to its current active set

ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE

ndash Call typesbull Circuit Switched always in

this statebull Packet Switched in this

state if transferring large volume of data

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 47

UE-Call states

bull CELL_FACH state(Forward Access Ch)

ndash No dedicated physical channel is allocated to the UE

ndash The UE continuously monitors a FACH in the downlink

ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel

ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update

ndash Radio not put to sleepndash For packet switched sessions

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 48

UE-Call states

bull CELL_PCH state (Paging Ch)ndash No dedicated physical

channel is allocated to the UE

ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash Sleep between pagesndash A logical session is still upndash The position of the UE is

known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 49

UE-Call states

bull URA_PCH State ndash No dedicated channel is

allocated to the UEndash The UE selects a PCH with

the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state

ndash Similar to CELL_PCH state only the at the URA level

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 50

Power Control-PC

bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to

ensure that there is enough power for mobiles at the cell edge

bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control

commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command

ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break

12 51

Power Control

bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss

by means of a downlink beacon signalndash Provide a coarse initial power setting of

the mobile at the beginning of a connection

ndash Apply only prior to initiating the transmission on RACH or CPCH

12 52

Packet Access in WCDMA

bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection

bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared

bull RNC can decide when and how to send packets based on type of packet traffic

ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech

ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video

ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing

ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail

bull RNC can assign a packet to a specific channel

Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 53

Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the

downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft

handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts

bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts

bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink

orthogonal code is reserved according to maximum bit rate

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 54

Packet Access in WCDMA

bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner

bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer

bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate

bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and

bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 55

Packet Access in WCDMA

bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased

bull Advantagesndash resources are in full usage due to longer transmission

timendash small variation in interference levelndash longer uplink range due to lower bit rate

bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 56

Packet Access in WCDMA

bull Time division is normally used with shared channels and code division is normally used with dedicated channels

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 57

Packet Access in WCDMA

bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users

could be based on required transmission powerbull Users close to the BS requires less

transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate

bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput

bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 58

HSDPA amp Enhance Uplink

bull HSDPA = High Speed Downlink Packet Access

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 59

HSDPA amp Enhance Uplink

bull Remember it is better (more efficient) to have a large number of users sharing a single server

bull This lead to a desire to have fast allocation of shared resources

bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code

bull Uplink resourcesndash Interference at the BS

bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)

bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)

12 60

HSDPA amp Enhance Uplink

bull UTRAN Architecture with HSDPA and enhanced uplink

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 61

HSDPA amp Enhance Uplink

bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK

modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and

coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function

moved to Node-B (WCDMA packet scheduling was done in the RNC)

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 62

HSDPA amp Enhance Uplink

bull Gain in Performance

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 63

HSDPA

bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to

individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes

bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)

12 64

HSDPA

bull New frame structurendash Five subframesW-CDMA

framendash User data can be

assigned on a subframe basis

ndash System can adjust in 2ms

ndash Each subframe is a transmission time interval (TTI) = 2ms

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 65

HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared

resource is also in the time domain

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 66

HSDPA

bull Another view

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

Spreading Code

12 67

HSDPAbull Link Adaptation

ndash Remember the fast power control is commonly used to

bull Maintain constant EnergyNoise ratiobull Reduce effect of fading

ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant

EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 68

HSDPA

ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)

ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum

bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user

bull 1 ndash 2 Mbs closer to achievable under real conditions

12 69

HSDPA

bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE

bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms

bull CQI (0-30) each mapping into a modulation SF etc

bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression

bull

12 70

HSDPA

bull Schedulingndash The scheduler decides which user

should get access to each TTI ndash CQI provides input into a Scheduler

bull Proportional Fair (PF) Scheduler can be uses

bull Implementation Specific

12 71

HSDPA

bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number

of spreading codes limits rate not power so likely receive first transmission

ndash At greater distances move from BS see more errors IR will require additional transmission but not many

ndash HARQ only retransmit upon an ACK or NACK

12 72

HSDPA

From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007

12 73

HSDPA

bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2

ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent

Scheduling

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 22

WCDMA

bull Spectrumndash 1920 MHz ndash 1980 MHz (uplink)ndash 2110 MHz ndash 2170 MHz (downlink)orndash 1850 MHz ndash 1910 MHz (uplink)ndash 1930 MHz ndash 1990 MHz (downlink)ndash Channel Spacing 5 Mhz

bull WCDMA is connected to the FDD Phy and the associated protocols Focus here

bull UTRAN-Universal Terrestrial Radio Access Network- is associated with the WCDMA radio Access Network

bull UMTS refers to the whole network

12 23

UMTS-FDD WCDMA

bull Wideband Direct Sequence Code Division Multiple Access

bull Does not assign a specific frequency to each user Instead every channel uses the full available spectrum

bull Individual conversations are encoded with a pseudo-random digital sequence

bull See httpwwwumtsworldcomtechnologyoverviewhtm

12 24

WCDMA Parameters

Channel BW 5 MHz

Forward RF Channel Structure Direct Spread

Chip Rate 384 Mcps

Frame Length 10 ms (38400 chips)

No of slotsframe 15

No of chipsslot 2560chips (Max 2560 bits)

Power Control Open and fast close loop (16 KHz)

Uplink Spreading Factor 4 to 256

Downlink Spreading Factor 4 to 512

12 25

Spreading Operation

bull Spreading means increasing the signal bandwidthbull Strictly speaking spreading includes two

operationsndash Channelisation (increases signal bandwidth) using

orthogonal codesndash Scrambling (does not affect the signal bandwidth) using

pseudo noise codes

12 26

Codes

Channellization Code Scrambling Code

Usage UL Separation of physical dataand control channels from same UEDL Separation of different userswithin one cell

UL Separation of terminalsDL Separation ofcellssectors

Length UL4-256 chipsDL4-512 chips

38400 chips

No of codes No of codes under one scrambling code= SF

UL Several millionDL 512

Code Family Orthogonal Variable Spreading Factor

Long 10ms code Gold codeShort code Extended S(2) code Family

Increase BW YES NO

12 27

UMTS Architecture

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

Cell site

Access Network

Core Network

User Equipment

12 28

UMTS Architecture

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 29

UMTS Architecture

bull User equipment-UEndash UMTS Subscriber Identity Module ndashUSIMndash Mobile Equipment- cell phone

bull UMTS Terrestrial Radio Access Networkndash Radio Network Subsystem

bull Node B- BSndash Transceiverndash Rate adaptationndash Radio resource managementndash Power control

12 30

UMTS Architecture

bull Radio Network Controller ndash RNCndash Radio access controlndash Connection controlndash Load congestion and admission controlndash Code allocation

ndash Core Networkbull MSCbull VLRbull HLRbull Gateway MSC ndash GMSC

ndash Supports circuit switched connectionsbull Serving GRPS Support Node ndash SGPRS

ndash Logical interface to UTRAN for packet transportraquo Session managementraquo Logical link management

bull Gateway GPRS Support Node ndash GGSNndash Supports packet switched transportndash This is an IP router

12 31

UMTS Protocol Architecture - User Plane

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

FP= Framing Protocol GTP-U= GPRS Tunneling Protocol-UserPDCP =Packet Data convergence Protocol

12 32

UMTS Protocol Stack

bull Radio Resource Control-RRC

bull Broadcastmulitcast control- BMC

bull Packet Data convergence Protocol- PDCPndash Header

compression

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

12 33

Packet SAR

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

12 34

Physical Layerbull The physical layer offers information transfer services to

the MAC layer These services are denoted as Transport channels (TrChrsquos) There are also Physical channels

bull Physical layer comprises following functionsndash 1048713 Various handover functionsndash 1048713 Error detection and report to higher layersndash 1048713 Multiplexing of transport channelsndash 1048713 Mapping of transport channels to physical channelsndash 1048713 Fast Close loop Power controlndash 1048713 Frequency and Time Synchronizationndash 1048713 Other responsibilities associated with transmitting and

receiving signals over the wireless mediandash Measurements

bull SIRbull Tx power Frame error rate etc

bull Physical channel is assigned a specific code

12 35

Transport amp Physical Channels

Transport Channel Physical Channel(ULDL) Dedicated Channel DCH Dedicated Physical Data Channel DPDCH

Dedicated Physical Control Channel DPCCH

(UL) Random Access Channel RACH Physical random access channel PRACH

(UL) Common packet channel CPCH Physical common packet channel PCPCH

(DL) Broadcast channel BCH Primary common control physical channel P-CCPCH

(DL) Forward access channel FACH(DL) Paging channel PCH

Secondary common control physical channel S-CCPCH

(DL) Downlink shared channel DSCH Physical downlink shared channel PDSCH

Signaling physical channels

Synchronization channel SCHCommon pilot channel CPICHAcquisition indication channel AICHPaging indication channel PICHCPCH Status indication channel CSICHCollision detectionChannel assignment indicator channel CDCA-ICH

12 36

UMTS FDD frame structure

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 37

MAC Layer

bull The MAC layer offers Data transfer to RLC and higher layers

bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically

bit rate within a predefined set per information unit delivered to the physical layer

ndash Service multiplexing on RACH FACH and dedicated channels

ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling

ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements

12 38

Physical Layer

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 39

RRC Layerbull The RRC layer offers the core network the following

servicesndash General control service which is used as an information

broadcast servicendash Notification service which is used for paging and

notification of a selected UEsndash Dedicated control service which is used for

establishmentrelease of a connection and transfer of messages using the connection

bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover

admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection

12 40

RLC Layer

bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is

appended to the information unit received from the higher layer

ndash Assured and un assured data transferbull The RLC layer comprises the following functions

ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the

WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the

control plane)ndash Duplicate detectionndash Flow controlndash Ciphering

12 41

RLC Layer-Modesbull Transparent-TM

ndash No header attachedndash SARndash SDU discard

bull Delete SDU if not sent before timer expiresndash Used for

bull Voicebull Some signaling

bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability

bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat

12 42

RLC Layer

From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the

UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

12 43

UE-Call states

bull Designed to ndash Take advantage of bursty nature of

datandash Save batter powerndash Maintains logical session and tracks

mobility but when appropriatendash releases dedicated resources to

increase overall capacityndash asleeps the UE

12 44

UE-Call states

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 45

UE-Call states

bull Idle modendash No active sessionndash UE monitors

Paging CHndash Sleeps between

paging cycles

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 46

UE-Call states

bull CELL_DCH state (Dedicated)ndash A dedicated physical

channel is allocated to the UE in uplink and downlink

ndash The UE is known on cell level according to its current active set

ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE

ndash Call typesbull Circuit Switched always in

this statebull Packet Switched in this

state if transferring large volume of data

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 47

UE-Call states

bull CELL_FACH state(Forward Access Ch)

ndash No dedicated physical channel is allocated to the UE

ndash The UE continuously monitors a FACH in the downlink

ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel

ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update

ndash Radio not put to sleepndash For packet switched sessions

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 48

UE-Call states

bull CELL_PCH state (Paging Ch)ndash No dedicated physical

channel is allocated to the UE

ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash Sleep between pagesndash A logical session is still upndash The position of the UE is

known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 49

UE-Call states

bull URA_PCH State ndash No dedicated channel is

allocated to the UEndash The UE selects a PCH with

the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state

ndash Similar to CELL_PCH state only the at the URA level

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 50

Power Control-PC

bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to

ensure that there is enough power for mobiles at the cell edge

bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control

commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command

ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break

12 51

Power Control

bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss

by means of a downlink beacon signalndash Provide a coarse initial power setting of

the mobile at the beginning of a connection

ndash Apply only prior to initiating the transmission on RACH or CPCH

12 52

Packet Access in WCDMA

bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection

bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared

bull RNC can decide when and how to send packets based on type of packet traffic

ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech

ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video

ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing

ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail

bull RNC can assign a packet to a specific channel

Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 53

Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the

downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft

handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts

bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts

bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink

orthogonal code is reserved according to maximum bit rate

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 54

Packet Access in WCDMA

bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner

bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer

bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate

bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and

bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 55

Packet Access in WCDMA

bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased

bull Advantagesndash resources are in full usage due to longer transmission

timendash small variation in interference levelndash longer uplink range due to lower bit rate

bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 56

Packet Access in WCDMA

bull Time division is normally used with shared channels and code division is normally used with dedicated channels

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 57

Packet Access in WCDMA

bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users

could be based on required transmission powerbull Users close to the BS requires less

transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate

bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput

bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 58

HSDPA amp Enhance Uplink

bull HSDPA = High Speed Downlink Packet Access

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 59

HSDPA amp Enhance Uplink

bull Remember it is better (more efficient) to have a large number of users sharing a single server

bull This lead to a desire to have fast allocation of shared resources

bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code

bull Uplink resourcesndash Interference at the BS

bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)

bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)

12 60

HSDPA amp Enhance Uplink

bull UTRAN Architecture with HSDPA and enhanced uplink

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 61

HSDPA amp Enhance Uplink

bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK

modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and

coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function

moved to Node-B (WCDMA packet scheduling was done in the RNC)

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 62

HSDPA amp Enhance Uplink

bull Gain in Performance

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 63

HSDPA

bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to

individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes

bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)

12 64

HSDPA

bull New frame structurendash Five subframesW-CDMA

framendash User data can be

assigned on a subframe basis

ndash System can adjust in 2ms

ndash Each subframe is a transmission time interval (TTI) = 2ms

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 65

HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared

resource is also in the time domain

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 66

HSDPA

bull Another view

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

Spreading Code

12 67

HSDPAbull Link Adaptation

ndash Remember the fast power control is commonly used to

bull Maintain constant EnergyNoise ratiobull Reduce effect of fading

ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant

EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 68

HSDPA

ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)

ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum

bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user

bull 1 ndash 2 Mbs closer to achievable under real conditions

12 69

HSDPA

bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE

bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms

bull CQI (0-30) each mapping into a modulation SF etc

bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression

bull

12 70

HSDPA

bull Schedulingndash The scheduler decides which user

should get access to each TTI ndash CQI provides input into a Scheduler

bull Proportional Fair (PF) Scheduler can be uses

bull Implementation Specific

12 71

HSDPA

bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number

of spreading codes limits rate not power so likely receive first transmission

ndash At greater distances move from BS see more errors IR will require additional transmission but not many

ndash HARQ only retransmit upon an ACK or NACK

12 72

HSDPA

From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007

12 73

HSDPA

bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2

ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent

Scheduling

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 23

UMTS-FDD WCDMA

bull Wideband Direct Sequence Code Division Multiple Access

bull Does not assign a specific frequency to each user Instead every channel uses the full available spectrum

bull Individual conversations are encoded with a pseudo-random digital sequence

bull See httpwwwumtsworldcomtechnologyoverviewhtm

12 24

WCDMA Parameters

Channel BW 5 MHz

Forward RF Channel Structure Direct Spread

Chip Rate 384 Mcps

Frame Length 10 ms (38400 chips)

No of slotsframe 15

No of chipsslot 2560chips (Max 2560 bits)

Power Control Open and fast close loop (16 KHz)

Uplink Spreading Factor 4 to 256

Downlink Spreading Factor 4 to 512

12 25

Spreading Operation

bull Spreading means increasing the signal bandwidthbull Strictly speaking spreading includes two

operationsndash Channelisation (increases signal bandwidth) using

orthogonal codesndash Scrambling (does not affect the signal bandwidth) using

pseudo noise codes

12 26

Codes

Channellization Code Scrambling Code

Usage UL Separation of physical dataand control channels from same UEDL Separation of different userswithin one cell

UL Separation of terminalsDL Separation ofcellssectors

Length UL4-256 chipsDL4-512 chips

38400 chips

No of codes No of codes under one scrambling code= SF

UL Several millionDL 512

Code Family Orthogonal Variable Spreading Factor

Long 10ms code Gold codeShort code Extended S(2) code Family

Increase BW YES NO

12 27

UMTS Architecture

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

Cell site

Access Network

Core Network

User Equipment

12 28

UMTS Architecture

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 29

UMTS Architecture

bull User equipment-UEndash UMTS Subscriber Identity Module ndashUSIMndash Mobile Equipment- cell phone

bull UMTS Terrestrial Radio Access Networkndash Radio Network Subsystem

bull Node B- BSndash Transceiverndash Rate adaptationndash Radio resource managementndash Power control

12 30

UMTS Architecture

bull Radio Network Controller ndash RNCndash Radio access controlndash Connection controlndash Load congestion and admission controlndash Code allocation

ndash Core Networkbull MSCbull VLRbull HLRbull Gateway MSC ndash GMSC

ndash Supports circuit switched connectionsbull Serving GRPS Support Node ndash SGPRS

ndash Logical interface to UTRAN for packet transportraquo Session managementraquo Logical link management

bull Gateway GPRS Support Node ndash GGSNndash Supports packet switched transportndash This is an IP router

12 31

UMTS Protocol Architecture - User Plane

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

FP= Framing Protocol GTP-U= GPRS Tunneling Protocol-UserPDCP =Packet Data convergence Protocol

12 32

UMTS Protocol Stack

bull Radio Resource Control-RRC

bull Broadcastmulitcast control- BMC

bull Packet Data convergence Protocol- PDCPndash Header

compression

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

12 33

Packet SAR

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

12 34

Physical Layerbull The physical layer offers information transfer services to

the MAC layer These services are denoted as Transport channels (TrChrsquos) There are also Physical channels

bull Physical layer comprises following functionsndash 1048713 Various handover functionsndash 1048713 Error detection and report to higher layersndash 1048713 Multiplexing of transport channelsndash 1048713 Mapping of transport channels to physical channelsndash 1048713 Fast Close loop Power controlndash 1048713 Frequency and Time Synchronizationndash 1048713 Other responsibilities associated with transmitting and

receiving signals over the wireless mediandash Measurements

bull SIRbull Tx power Frame error rate etc

bull Physical channel is assigned a specific code

12 35

Transport amp Physical Channels

Transport Channel Physical Channel(ULDL) Dedicated Channel DCH Dedicated Physical Data Channel DPDCH

Dedicated Physical Control Channel DPCCH

(UL) Random Access Channel RACH Physical random access channel PRACH

(UL) Common packet channel CPCH Physical common packet channel PCPCH

(DL) Broadcast channel BCH Primary common control physical channel P-CCPCH

(DL) Forward access channel FACH(DL) Paging channel PCH

Secondary common control physical channel S-CCPCH

(DL) Downlink shared channel DSCH Physical downlink shared channel PDSCH

Signaling physical channels

Synchronization channel SCHCommon pilot channel CPICHAcquisition indication channel AICHPaging indication channel PICHCPCH Status indication channel CSICHCollision detectionChannel assignment indicator channel CDCA-ICH

12 36

UMTS FDD frame structure

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 37

MAC Layer

bull The MAC layer offers Data transfer to RLC and higher layers

bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically

bit rate within a predefined set per information unit delivered to the physical layer

ndash Service multiplexing on RACH FACH and dedicated channels

ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling

ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements

12 38

Physical Layer

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 39

RRC Layerbull The RRC layer offers the core network the following

servicesndash General control service which is used as an information

broadcast servicendash Notification service which is used for paging and

notification of a selected UEsndash Dedicated control service which is used for

establishmentrelease of a connection and transfer of messages using the connection

bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover

admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection

12 40

RLC Layer

bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is

appended to the information unit received from the higher layer

ndash Assured and un assured data transferbull The RLC layer comprises the following functions

ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the

WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the

control plane)ndash Duplicate detectionndash Flow controlndash Ciphering

12 41

RLC Layer-Modesbull Transparent-TM

ndash No header attachedndash SARndash SDU discard

bull Delete SDU if not sent before timer expiresndash Used for

bull Voicebull Some signaling

bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability

bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat

12 42

RLC Layer

From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the

UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

12 43

UE-Call states

bull Designed to ndash Take advantage of bursty nature of

datandash Save batter powerndash Maintains logical session and tracks

mobility but when appropriatendash releases dedicated resources to

increase overall capacityndash asleeps the UE

12 44

UE-Call states

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 45

UE-Call states

bull Idle modendash No active sessionndash UE monitors

Paging CHndash Sleeps between

paging cycles

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 46

UE-Call states

bull CELL_DCH state (Dedicated)ndash A dedicated physical

channel is allocated to the UE in uplink and downlink

ndash The UE is known on cell level according to its current active set

ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE

ndash Call typesbull Circuit Switched always in

this statebull Packet Switched in this

state if transferring large volume of data

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 47

UE-Call states

bull CELL_FACH state(Forward Access Ch)

ndash No dedicated physical channel is allocated to the UE

ndash The UE continuously monitors a FACH in the downlink

ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel

ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update

ndash Radio not put to sleepndash For packet switched sessions

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 48

UE-Call states

bull CELL_PCH state (Paging Ch)ndash No dedicated physical

channel is allocated to the UE

ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash Sleep between pagesndash A logical session is still upndash The position of the UE is

known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 49

UE-Call states

bull URA_PCH State ndash No dedicated channel is

allocated to the UEndash The UE selects a PCH with

the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state

ndash Similar to CELL_PCH state only the at the URA level

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 50

Power Control-PC

bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to

ensure that there is enough power for mobiles at the cell edge

bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control

commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command

ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break

12 51

Power Control

bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss

by means of a downlink beacon signalndash Provide a coarse initial power setting of

the mobile at the beginning of a connection

ndash Apply only prior to initiating the transmission on RACH or CPCH

12 52

Packet Access in WCDMA

bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection

bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared

bull RNC can decide when and how to send packets based on type of packet traffic

ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech

ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video

ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing

ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail

bull RNC can assign a packet to a specific channel

Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 53

Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the

downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft

handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts

bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts

bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink

orthogonal code is reserved according to maximum bit rate

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 54

Packet Access in WCDMA

bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner

bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer

bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate

bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and

bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 55

Packet Access in WCDMA

bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased

bull Advantagesndash resources are in full usage due to longer transmission

timendash small variation in interference levelndash longer uplink range due to lower bit rate

bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 56

Packet Access in WCDMA

bull Time division is normally used with shared channels and code division is normally used with dedicated channels

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 57

Packet Access in WCDMA

bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users

could be based on required transmission powerbull Users close to the BS requires less

transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate

bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput

bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 58

HSDPA amp Enhance Uplink

bull HSDPA = High Speed Downlink Packet Access

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 59

HSDPA amp Enhance Uplink

bull Remember it is better (more efficient) to have a large number of users sharing a single server

bull This lead to a desire to have fast allocation of shared resources

bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code

bull Uplink resourcesndash Interference at the BS

bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)

bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)

12 60

HSDPA amp Enhance Uplink

bull UTRAN Architecture with HSDPA and enhanced uplink

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 61

HSDPA amp Enhance Uplink

bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK

modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and

coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function

moved to Node-B (WCDMA packet scheduling was done in the RNC)

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 62

HSDPA amp Enhance Uplink

bull Gain in Performance

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 63

HSDPA

bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to

individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes

bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)

12 64

HSDPA

bull New frame structurendash Five subframesW-CDMA

framendash User data can be

assigned on a subframe basis

ndash System can adjust in 2ms

ndash Each subframe is a transmission time interval (TTI) = 2ms

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 65

HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared

resource is also in the time domain

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 66

HSDPA

bull Another view

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

Spreading Code

12 67

HSDPAbull Link Adaptation

ndash Remember the fast power control is commonly used to

bull Maintain constant EnergyNoise ratiobull Reduce effect of fading

ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant

EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 68

HSDPA

ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)

ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum

bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user

bull 1 ndash 2 Mbs closer to achievable under real conditions

12 69

HSDPA

bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE

bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms

bull CQI (0-30) each mapping into a modulation SF etc

bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression

bull

12 70

HSDPA

bull Schedulingndash The scheduler decides which user

should get access to each TTI ndash CQI provides input into a Scheduler

bull Proportional Fair (PF) Scheduler can be uses

bull Implementation Specific

12 71

HSDPA

bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number

of spreading codes limits rate not power so likely receive first transmission

ndash At greater distances move from BS see more errors IR will require additional transmission but not many

ndash HARQ only retransmit upon an ACK or NACK

12 72

HSDPA

From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007

12 73

HSDPA

bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2

ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent

Scheduling

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 24

WCDMA Parameters

Channel BW 5 MHz

Forward RF Channel Structure Direct Spread

Chip Rate 384 Mcps

Frame Length 10 ms (38400 chips)

No of slotsframe 15

No of chipsslot 2560chips (Max 2560 bits)

Power Control Open and fast close loop (16 KHz)

Uplink Spreading Factor 4 to 256

Downlink Spreading Factor 4 to 512

12 25

Spreading Operation

bull Spreading means increasing the signal bandwidthbull Strictly speaking spreading includes two

operationsndash Channelisation (increases signal bandwidth) using

orthogonal codesndash Scrambling (does not affect the signal bandwidth) using

pseudo noise codes

12 26

Codes

Channellization Code Scrambling Code

Usage UL Separation of physical dataand control channels from same UEDL Separation of different userswithin one cell

UL Separation of terminalsDL Separation ofcellssectors

Length UL4-256 chipsDL4-512 chips

38400 chips

No of codes No of codes under one scrambling code= SF

UL Several millionDL 512

Code Family Orthogonal Variable Spreading Factor

Long 10ms code Gold codeShort code Extended S(2) code Family

Increase BW YES NO

12 27

UMTS Architecture

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

Cell site

Access Network

Core Network

User Equipment

12 28

UMTS Architecture

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 29

UMTS Architecture

bull User equipment-UEndash UMTS Subscriber Identity Module ndashUSIMndash Mobile Equipment- cell phone

bull UMTS Terrestrial Radio Access Networkndash Radio Network Subsystem

bull Node B- BSndash Transceiverndash Rate adaptationndash Radio resource managementndash Power control

12 30

UMTS Architecture

bull Radio Network Controller ndash RNCndash Radio access controlndash Connection controlndash Load congestion and admission controlndash Code allocation

ndash Core Networkbull MSCbull VLRbull HLRbull Gateway MSC ndash GMSC

ndash Supports circuit switched connectionsbull Serving GRPS Support Node ndash SGPRS

ndash Logical interface to UTRAN for packet transportraquo Session managementraquo Logical link management

bull Gateway GPRS Support Node ndash GGSNndash Supports packet switched transportndash This is an IP router

12 31

UMTS Protocol Architecture - User Plane

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

FP= Framing Protocol GTP-U= GPRS Tunneling Protocol-UserPDCP =Packet Data convergence Protocol

12 32

UMTS Protocol Stack

bull Radio Resource Control-RRC

bull Broadcastmulitcast control- BMC

bull Packet Data convergence Protocol- PDCPndash Header

compression

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

12 33

Packet SAR

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

12 34

Physical Layerbull The physical layer offers information transfer services to

the MAC layer These services are denoted as Transport channels (TrChrsquos) There are also Physical channels

bull Physical layer comprises following functionsndash 1048713 Various handover functionsndash 1048713 Error detection and report to higher layersndash 1048713 Multiplexing of transport channelsndash 1048713 Mapping of transport channels to physical channelsndash 1048713 Fast Close loop Power controlndash 1048713 Frequency and Time Synchronizationndash 1048713 Other responsibilities associated with transmitting and

receiving signals over the wireless mediandash Measurements

bull SIRbull Tx power Frame error rate etc

bull Physical channel is assigned a specific code

12 35

Transport amp Physical Channels

Transport Channel Physical Channel(ULDL) Dedicated Channel DCH Dedicated Physical Data Channel DPDCH

Dedicated Physical Control Channel DPCCH

(UL) Random Access Channel RACH Physical random access channel PRACH

(UL) Common packet channel CPCH Physical common packet channel PCPCH

(DL) Broadcast channel BCH Primary common control physical channel P-CCPCH

(DL) Forward access channel FACH(DL) Paging channel PCH

Secondary common control physical channel S-CCPCH

(DL) Downlink shared channel DSCH Physical downlink shared channel PDSCH

Signaling physical channels

Synchronization channel SCHCommon pilot channel CPICHAcquisition indication channel AICHPaging indication channel PICHCPCH Status indication channel CSICHCollision detectionChannel assignment indicator channel CDCA-ICH

12 36

UMTS FDD frame structure

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 37

MAC Layer

bull The MAC layer offers Data transfer to RLC and higher layers

bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically

bit rate within a predefined set per information unit delivered to the physical layer

ndash Service multiplexing on RACH FACH and dedicated channels

ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling

ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements

12 38

Physical Layer

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 39

RRC Layerbull The RRC layer offers the core network the following

servicesndash General control service which is used as an information

broadcast servicendash Notification service which is used for paging and

notification of a selected UEsndash Dedicated control service which is used for

establishmentrelease of a connection and transfer of messages using the connection

bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover

admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection

12 40

RLC Layer

bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is

appended to the information unit received from the higher layer

ndash Assured and un assured data transferbull The RLC layer comprises the following functions

ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the

WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the

control plane)ndash Duplicate detectionndash Flow controlndash Ciphering

12 41

RLC Layer-Modesbull Transparent-TM

ndash No header attachedndash SARndash SDU discard

bull Delete SDU if not sent before timer expiresndash Used for

bull Voicebull Some signaling

bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability

bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat

12 42

RLC Layer

From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the

UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

12 43

UE-Call states

bull Designed to ndash Take advantage of bursty nature of

datandash Save batter powerndash Maintains logical session and tracks

mobility but when appropriatendash releases dedicated resources to

increase overall capacityndash asleeps the UE

12 44

UE-Call states

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 45

UE-Call states

bull Idle modendash No active sessionndash UE monitors

Paging CHndash Sleeps between

paging cycles

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 46

UE-Call states

bull CELL_DCH state (Dedicated)ndash A dedicated physical

channel is allocated to the UE in uplink and downlink

ndash The UE is known on cell level according to its current active set

ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE

ndash Call typesbull Circuit Switched always in

this statebull Packet Switched in this

state if transferring large volume of data

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 47

UE-Call states

bull CELL_FACH state(Forward Access Ch)

ndash No dedicated physical channel is allocated to the UE

ndash The UE continuously monitors a FACH in the downlink

ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel

ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update

ndash Radio not put to sleepndash For packet switched sessions

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 48

UE-Call states

bull CELL_PCH state (Paging Ch)ndash No dedicated physical

channel is allocated to the UE

ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash Sleep between pagesndash A logical session is still upndash The position of the UE is

known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 49

UE-Call states

bull URA_PCH State ndash No dedicated channel is

allocated to the UEndash The UE selects a PCH with

the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state

ndash Similar to CELL_PCH state only the at the URA level

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 50

Power Control-PC

bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to

ensure that there is enough power for mobiles at the cell edge

bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control

commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command

ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break

12 51

Power Control

bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss

by means of a downlink beacon signalndash Provide a coarse initial power setting of

the mobile at the beginning of a connection

ndash Apply only prior to initiating the transmission on RACH or CPCH

12 52

Packet Access in WCDMA

bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection

bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared

bull RNC can decide when and how to send packets based on type of packet traffic

ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech

ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video

ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing

ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail

bull RNC can assign a packet to a specific channel

Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 53

Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the

downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft

handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts

bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts

bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink

orthogonal code is reserved according to maximum bit rate

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 54

Packet Access in WCDMA

bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner

bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer

bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate

bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and

bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 55

Packet Access in WCDMA

bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased

bull Advantagesndash resources are in full usage due to longer transmission

timendash small variation in interference levelndash longer uplink range due to lower bit rate

bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 56

Packet Access in WCDMA

bull Time division is normally used with shared channels and code division is normally used with dedicated channels

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 57

Packet Access in WCDMA

bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users

could be based on required transmission powerbull Users close to the BS requires less

transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate

bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput

bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 58

HSDPA amp Enhance Uplink

bull HSDPA = High Speed Downlink Packet Access

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 59

HSDPA amp Enhance Uplink

bull Remember it is better (more efficient) to have a large number of users sharing a single server

bull This lead to a desire to have fast allocation of shared resources

bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code

bull Uplink resourcesndash Interference at the BS

bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)

bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)

12 60

HSDPA amp Enhance Uplink

bull UTRAN Architecture with HSDPA and enhanced uplink

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 61

HSDPA amp Enhance Uplink

bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK

modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and

coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function

moved to Node-B (WCDMA packet scheduling was done in the RNC)

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 62

HSDPA amp Enhance Uplink

bull Gain in Performance

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 63

HSDPA

bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to

individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes

bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)

12 64

HSDPA

bull New frame structurendash Five subframesW-CDMA

framendash User data can be

assigned on a subframe basis

ndash System can adjust in 2ms

ndash Each subframe is a transmission time interval (TTI) = 2ms

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 65

HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared

resource is also in the time domain

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 66

HSDPA

bull Another view

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

Spreading Code

12 67

HSDPAbull Link Adaptation

ndash Remember the fast power control is commonly used to

bull Maintain constant EnergyNoise ratiobull Reduce effect of fading

ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant

EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 68

HSDPA

ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)

ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum

bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user

bull 1 ndash 2 Mbs closer to achievable under real conditions

12 69

HSDPA

bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE

bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms

bull CQI (0-30) each mapping into a modulation SF etc

bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression

bull

12 70

HSDPA

bull Schedulingndash The scheduler decides which user

should get access to each TTI ndash CQI provides input into a Scheduler

bull Proportional Fair (PF) Scheduler can be uses

bull Implementation Specific

12 71

HSDPA

bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number

of spreading codes limits rate not power so likely receive first transmission

ndash At greater distances move from BS see more errors IR will require additional transmission but not many

ndash HARQ only retransmit upon an ACK or NACK

12 72

HSDPA

From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007

12 73

HSDPA

bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2

ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent

Scheduling

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 25

Spreading Operation

bull Spreading means increasing the signal bandwidthbull Strictly speaking spreading includes two

operationsndash Channelisation (increases signal bandwidth) using

orthogonal codesndash Scrambling (does not affect the signal bandwidth) using

pseudo noise codes

12 26

Codes

Channellization Code Scrambling Code

Usage UL Separation of physical dataand control channels from same UEDL Separation of different userswithin one cell

UL Separation of terminalsDL Separation ofcellssectors

Length UL4-256 chipsDL4-512 chips

38400 chips

No of codes No of codes under one scrambling code= SF

UL Several millionDL 512

Code Family Orthogonal Variable Spreading Factor

Long 10ms code Gold codeShort code Extended S(2) code Family

Increase BW YES NO

12 27

UMTS Architecture

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

Cell site

Access Network

Core Network

User Equipment

12 28

UMTS Architecture

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 29

UMTS Architecture

bull User equipment-UEndash UMTS Subscriber Identity Module ndashUSIMndash Mobile Equipment- cell phone

bull UMTS Terrestrial Radio Access Networkndash Radio Network Subsystem

bull Node B- BSndash Transceiverndash Rate adaptationndash Radio resource managementndash Power control

12 30

UMTS Architecture

bull Radio Network Controller ndash RNCndash Radio access controlndash Connection controlndash Load congestion and admission controlndash Code allocation

ndash Core Networkbull MSCbull VLRbull HLRbull Gateway MSC ndash GMSC

ndash Supports circuit switched connectionsbull Serving GRPS Support Node ndash SGPRS

ndash Logical interface to UTRAN for packet transportraquo Session managementraquo Logical link management

bull Gateway GPRS Support Node ndash GGSNndash Supports packet switched transportndash This is an IP router

12 31

UMTS Protocol Architecture - User Plane

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

FP= Framing Protocol GTP-U= GPRS Tunneling Protocol-UserPDCP =Packet Data convergence Protocol

12 32

UMTS Protocol Stack

bull Radio Resource Control-RRC

bull Broadcastmulitcast control- BMC

bull Packet Data convergence Protocol- PDCPndash Header

compression

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

12 33

Packet SAR

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

12 34

Physical Layerbull The physical layer offers information transfer services to

the MAC layer These services are denoted as Transport channels (TrChrsquos) There are also Physical channels

bull Physical layer comprises following functionsndash 1048713 Various handover functionsndash 1048713 Error detection and report to higher layersndash 1048713 Multiplexing of transport channelsndash 1048713 Mapping of transport channels to physical channelsndash 1048713 Fast Close loop Power controlndash 1048713 Frequency and Time Synchronizationndash 1048713 Other responsibilities associated with transmitting and

receiving signals over the wireless mediandash Measurements

bull SIRbull Tx power Frame error rate etc

bull Physical channel is assigned a specific code

12 35

Transport amp Physical Channels

Transport Channel Physical Channel(ULDL) Dedicated Channel DCH Dedicated Physical Data Channel DPDCH

Dedicated Physical Control Channel DPCCH

(UL) Random Access Channel RACH Physical random access channel PRACH

(UL) Common packet channel CPCH Physical common packet channel PCPCH

(DL) Broadcast channel BCH Primary common control physical channel P-CCPCH

(DL) Forward access channel FACH(DL) Paging channel PCH

Secondary common control physical channel S-CCPCH

(DL) Downlink shared channel DSCH Physical downlink shared channel PDSCH

Signaling physical channels

Synchronization channel SCHCommon pilot channel CPICHAcquisition indication channel AICHPaging indication channel PICHCPCH Status indication channel CSICHCollision detectionChannel assignment indicator channel CDCA-ICH

12 36

UMTS FDD frame structure

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 37

MAC Layer

bull The MAC layer offers Data transfer to RLC and higher layers

bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically

bit rate within a predefined set per information unit delivered to the physical layer

ndash Service multiplexing on RACH FACH and dedicated channels

ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling

ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements

12 38

Physical Layer

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 39

RRC Layerbull The RRC layer offers the core network the following

servicesndash General control service which is used as an information

broadcast servicendash Notification service which is used for paging and

notification of a selected UEsndash Dedicated control service which is used for

establishmentrelease of a connection and transfer of messages using the connection

bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover

admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection

12 40

RLC Layer

bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is

appended to the information unit received from the higher layer

ndash Assured and un assured data transferbull The RLC layer comprises the following functions

ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the

WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the

control plane)ndash Duplicate detectionndash Flow controlndash Ciphering

12 41

RLC Layer-Modesbull Transparent-TM

ndash No header attachedndash SARndash SDU discard

bull Delete SDU if not sent before timer expiresndash Used for

bull Voicebull Some signaling

bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability

bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat

12 42

RLC Layer

From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the

UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

12 43

UE-Call states

bull Designed to ndash Take advantage of bursty nature of

datandash Save batter powerndash Maintains logical session and tracks

mobility but when appropriatendash releases dedicated resources to

increase overall capacityndash asleeps the UE

12 44

UE-Call states

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 45

UE-Call states

bull Idle modendash No active sessionndash UE monitors

Paging CHndash Sleeps between

paging cycles

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 46

UE-Call states

bull CELL_DCH state (Dedicated)ndash A dedicated physical

channel is allocated to the UE in uplink and downlink

ndash The UE is known on cell level according to its current active set

ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE

ndash Call typesbull Circuit Switched always in

this statebull Packet Switched in this

state if transferring large volume of data

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 47

UE-Call states

bull CELL_FACH state(Forward Access Ch)

ndash No dedicated physical channel is allocated to the UE

ndash The UE continuously monitors a FACH in the downlink

ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel

ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update

ndash Radio not put to sleepndash For packet switched sessions

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 48

UE-Call states

bull CELL_PCH state (Paging Ch)ndash No dedicated physical

channel is allocated to the UE

ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash Sleep between pagesndash A logical session is still upndash The position of the UE is

known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 49

UE-Call states

bull URA_PCH State ndash No dedicated channel is

allocated to the UEndash The UE selects a PCH with

the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state

ndash Similar to CELL_PCH state only the at the URA level

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 50

Power Control-PC

bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to

ensure that there is enough power for mobiles at the cell edge

bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control

commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command

ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break

12 51

Power Control

bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss

by means of a downlink beacon signalndash Provide a coarse initial power setting of

the mobile at the beginning of a connection

ndash Apply only prior to initiating the transmission on RACH or CPCH

12 52

Packet Access in WCDMA

bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection

bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared

bull RNC can decide when and how to send packets based on type of packet traffic

ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech

ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video

ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing

ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail

bull RNC can assign a packet to a specific channel

Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 53

Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the

downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft

handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts

bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts

bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink

orthogonal code is reserved according to maximum bit rate

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 54

Packet Access in WCDMA

bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner

bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer

bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate

bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and

bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 55

Packet Access in WCDMA

bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased

bull Advantagesndash resources are in full usage due to longer transmission

timendash small variation in interference levelndash longer uplink range due to lower bit rate

bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 56

Packet Access in WCDMA

bull Time division is normally used with shared channels and code division is normally used with dedicated channels

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 57

Packet Access in WCDMA

bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users

could be based on required transmission powerbull Users close to the BS requires less

transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate

bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput

bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 58

HSDPA amp Enhance Uplink

bull HSDPA = High Speed Downlink Packet Access

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 59

HSDPA amp Enhance Uplink

bull Remember it is better (more efficient) to have a large number of users sharing a single server

bull This lead to a desire to have fast allocation of shared resources

bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code

bull Uplink resourcesndash Interference at the BS

bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)

bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)

12 60

HSDPA amp Enhance Uplink

bull UTRAN Architecture with HSDPA and enhanced uplink

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 61

HSDPA amp Enhance Uplink

bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK

modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and

coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function

moved to Node-B (WCDMA packet scheduling was done in the RNC)

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 62

HSDPA amp Enhance Uplink

bull Gain in Performance

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 63

HSDPA

bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to

individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes

bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)

12 64

HSDPA

bull New frame structurendash Five subframesW-CDMA

framendash User data can be

assigned on a subframe basis

ndash System can adjust in 2ms

ndash Each subframe is a transmission time interval (TTI) = 2ms

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 65

HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared

resource is also in the time domain

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 66

HSDPA

bull Another view

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

Spreading Code

12 67

HSDPAbull Link Adaptation

ndash Remember the fast power control is commonly used to

bull Maintain constant EnergyNoise ratiobull Reduce effect of fading

ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant

EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 68

HSDPA

ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)

ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum

bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user

bull 1 ndash 2 Mbs closer to achievable under real conditions

12 69

HSDPA

bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE

bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms

bull CQI (0-30) each mapping into a modulation SF etc

bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression

bull

12 70

HSDPA

bull Schedulingndash The scheduler decides which user

should get access to each TTI ndash CQI provides input into a Scheduler

bull Proportional Fair (PF) Scheduler can be uses

bull Implementation Specific

12 71

HSDPA

bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number

of spreading codes limits rate not power so likely receive first transmission

ndash At greater distances move from BS see more errors IR will require additional transmission but not many

ndash HARQ only retransmit upon an ACK or NACK

12 72

HSDPA

From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007

12 73

HSDPA

bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2

ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent

Scheduling

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 26

Codes

Channellization Code Scrambling Code

Usage UL Separation of physical dataand control channels from same UEDL Separation of different userswithin one cell

UL Separation of terminalsDL Separation ofcellssectors

Length UL4-256 chipsDL4-512 chips

38400 chips

No of codes No of codes under one scrambling code= SF

UL Several millionDL 512

Code Family Orthogonal Variable Spreading Factor

Long 10ms code Gold codeShort code Extended S(2) code Family

Increase BW YES NO

12 27

UMTS Architecture

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

Cell site

Access Network

Core Network

User Equipment

12 28

UMTS Architecture

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 29

UMTS Architecture

bull User equipment-UEndash UMTS Subscriber Identity Module ndashUSIMndash Mobile Equipment- cell phone

bull UMTS Terrestrial Radio Access Networkndash Radio Network Subsystem

bull Node B- BSndash Transceiverndash Rate adaptationndash Radio resource managementndash Power control

12 30

UMTS Architecture

bull Radio Network Controller ndash RNCndash Radio access controlndash Connection controlndash Load congestion and admission controlndash Code allocation

ndash Core Networkbull MSCbull VLRbull HLRbull Gateway MSC ndash GMSC

ndash Supports circuit switched connectionsbull Serving GRPS Support Node ndash SGPRS

ndash Logical interface to UTRAN for packet transportraquo Session managementraquo Logical link management

bull Gateway GPRS Support Node ndash GGSNndash Supports packet switched transportndash This is an IP router

12 31

UMTS Protocol Architecture - User Plane

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

FP= Framing Protocol GTP-U= GPRS Tunneling Protocol-UserPDCP =Packet Data convergence Protocol

12 32

UMTS Protocol Stack

bull Radio Resource Control-RRC

bull Broadcastmulitcast control- BMC

bull Packet Data convergence Protocol- PDCPndash Header

compression

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

12 33

Packet SAR

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

12 34

Physical Layerbull The physical layer offers information transfer services to

the MAC layer These services are denoted as Transport channels (TrChrsquos) There are also Physical channels

bull Physical layer comprises following functionsndash 1048713 Various handover functionsndash 1048713 Error detection and report to higher layersndash 1048713 Multiplexing of transport channelsndash 1048713 Mapping of transport channels to physical channelsndash 1048713 Fast Close loop Power controlndash 1048713 Frequency and Time Synchronizationndash 1048713 Other responsibilities associated with transmitting and

receiving signals over the wireless mediandash Measurements

bull SIRbull Tx power Frame error rate etc

bull Physical channel is assigned a specific code

12 35

Transport amp Physical Channels

Transport Channel Physical Channel(ULDL) Dedicated Channel DCH Dedicated Physical Data Channel DPDCH

Dedicated Physical Control Channel DPCCH

(UL) Random Access Channel RACH Physical random access channel PRACH

(UL) Common packet channel CPCH Physical common packet channel PCPCH

(DL) Broadcast channel BCH Primary common control physical channel P-CCPCH

(DL) Forward access channel FACH(DL) Paging channel PCH

Secondary common control physical channel S-CCPCH

(DL) Downlink shared channel DSCH Physical downlink shared channel PDSCH

Signaling physical channels

Synchronization channel SCHCommon pilot channel CPICHAcquisition indication channel AICHPaging indication channel PICHCPCH Status indication channel CSICHCollision detectionChannel assignment indicator channel CDCA-ICH

12 36

UMTS FDD frame structure

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 37

MAC Layer

bull The MAC layer offers Data transfer to RLC and higher layers

bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically

bit rate within a predefined set per information unit delivered to the physical layer

ndash Service multiplexing on RACH FACH and dedicated channels

ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling

ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements

12 38

Physical Layer

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 39

RRC Layerbull The RRC layer offers the core network the following

servicesndash General control service which is used as an information

broadcast servicendash Notification service which is used for paging and

notification of a selected UEsndash Dedicated control service which is used for

establishmentrelease of a connection and transfer of messages using the connection

bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover

admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection

12 40

RLC Layer

bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is

appended to the information unit received from the higher layer

ndash Assured and un assured data transferbull The RLC layer comprises the following functions

ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the

WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the

control plane)ndash Duplicate detectionndash Flow controlndash Ciphering

12 41

RLC Layer-Modesbull Transparent-TM

ndash No header attachedndash SARndash SDU discard

bull Delete SDU if not sent before timer expiresndash Used for

bull Voicebull Some signaling

bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability

bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat

12 42

RLC Layer

From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the

UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

12 43

UE-Call states

bull Designed to ndash Take advantage of bursty nature of

datandash Save batter powerndash Maintains logical session and tracks

mobility but when appropriatendash releases dedicated resources to

increase overall capacityndash asleeps the UE

12 44

UE-Call states

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 45

UE-Call states

bull Idle modendash No active sessionndash UE monitors

Paging CHndash Sleeps between

paging cycles

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 46

UE-Call states

bull CELL_DCH state (Dedicated)ndash A dedicated physical

channel is allocated to the UE in uplink and downlink

ndash The UE is known on cell level according to its current active set

ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE

ndash Call typesbull Circuit Switched always in

this statebull Packet Switched in this

state if transferring large volume of data

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 47

UE-Call states

bull CELL_FACH state(Forward Access Ch)

ndash No dedicated physical channel is allocated to the UE

ndash The UE continuously monitors a FACH in the downlink

ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel

ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update

ndash Radio not put to sleepndash For packet switched sessions

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 48

UE-Call states

bull CELL_PCH state (Paging Ch)ndash No dedicated physical

channel is allocated to the UE

ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash Sleep between pagesndash A logical session is still upndash The position of the UE is

known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 49

UE-Call states

bull URA_PCH State ndash No dedicated channel is

allocated to the UEndash The UE selects a PCH with

the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state

ndash Similar to CELL_PCH state only the at the URA level

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 50

Power Control-PC

bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to

ensure that there is enough power for mobiles at the cell edge

bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control

commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command

ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break

12 51

Power Control

bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss

by means of a downlink beacon signalndash Provide a coarse initial power setting of

the mobile at the beginning of a connection

ndash Apply only prior to initiating the transmission on RACH or CPCH

12 52

Packet Access in WCDMA

bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection

bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared

bull RNC can decide when and how to send packets based on type of packet traffic

ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech

ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video

ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing

ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail

bull RNC can assign a packet to a specific channel

Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 53

Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the

downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft

handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts

bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts

bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink

orthogonal code is reserved according to maximum bit rate

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 54

Packet Access in WCDMA

bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner

bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer

bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate

bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and

bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 55

Packet Access in WCDMA

bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased

bull Advantagesndash resources are in full usage due to longer transmission

timendash small variation in interference levelndash longer uplink range due to lower bit rate

bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 56

Packet Access in WCDMA

bull Time division is normally used with shared channels and code division is normally used with dedicated channels

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 57

Packet Access in WCDMA

bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users

could be based on required transmission powerbull Users close to the BS requires less

transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate

bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput

bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 58

HSDPA amp Enhance Uplink

bull HSDPA = High Speed Downlink Packet Access

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 59

HSDPA amp Enhance Uplink

bull Remember it is better (more efficient) to have a large number of users sharing a single server

bull This lead to a desire to have fast allocation of shared resources

bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code

bull Uplink resourcesndash Interference at the BS

bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)

bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)

12 60

HSDPA amp Enhance Uplink

bull UTRAN Architecture with HSDPA and enhanced uplink

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 61

HSDPA amp Enhance Uplink

bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK

modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and

coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function

moved to Node-B (WCDMA packet scheduling was done in the RNC)

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 62

HSDPA amp Enhance Uplink

bull Gain in Performance

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 63

HSDPA

bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to

individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes

bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)

12 64

HSDPA

bull New frame structurendash Five subframesW-CDMA

framendash User data can be

assigned on a subframe basis

ndash System can adjust in 2ms

ndash Each subframe is a transmission time interval (TTI) = 2ms

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 65

HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared

resource is also in the time domain

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 66

HSDPA

bull Another view

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

Spreading Code

12 67

HSDPAbull Link Adaptation

ndash Remember the fast power control is commonly used to

bull Maintain constant EnergyNoise ratiobull Reduce effect of fading

ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant

EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 68

HSDPA

ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)

ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum

bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user

bull 1 ndash 2 Mbs closer to achievable under real conditions

12 69

HSDPA

bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE

bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms

bull CQI (0-30) each mapping into a modulation SF etc

bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression

bull

12 70

HSDPA

bull Schedulingndash The scheduler decides which user

should get access to each TTI ndash CQI provides input into a Scheduler

bull Proportional Fair (PF) Scheduler can be uses

bull Implementation Specific

12 71

HSDPA

bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number

of spreading codes limits rate not power so likely receive first transmission

ndash At greater distances move from BS see more errors IR will require additional transmission but not many

ndash HARQ only retransmit upon an ACK or NACK

12 72

HSDPA

From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007

12 73

HSDPA

bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2

ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent

Scheduling

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 27

UMTS Architecture

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

Cell site

Access Network

Core Network

User Equipment

12 28

UMTS Architecture

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 29

UMTS Architecture

bull User equipment-UEndash UMTS Subscriber Identity Module ndashUSIMndash Mobile Equipment- cell phone

bull UMTS Terrestrial Radio Access Networkndash Radio Network Subsystem

bull Node B- BSndash Transceiverndash Rate adaptationndash Radio resource managementndash Power control

12 30

UMTS Architecture

bull Radio Network Controller ndash RNCndash Radio access controlndash Connection controlndash Load congestion and admission controlndash Code allocation

ndash Core Networkbull MSCbull VLRbull HLRbull Gateway MSC ndash GMSC

ndash Supports circuit switched connectionsbull Serving GRPS Support Node ndash SGPRS

ndash Logical interface to UTRAN for packet transportraquo Session managementraquo Logical link management

bull Gateway GPRS Support Node ndash GGSNndash Supports packet switched transportndash This is an IP router

12 31

UMTS Protocol Architecture - User Plane

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

FP= Framing Protocol GTP-U= GPRS Tunneling Protocol-UserPDCP =Packet Data convergence Protocol

12 32

UMTS Protocol Stack

bull Radio Resource Control-RRC

bull Broadcastmulitcast control- BMC

bull Packet Data convergence Protocol- PDCPndash Header

compression

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

12 33

Packet SAR

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

12 34

Physical Layerbull The physical layer offers information transfer services to

the MAC layer These services are denoted as Transport channels (TrChrsquos) There are also Physical channels

bull Physical layer comprises following functionsndash 1048713 Various handover functionsndash 1048713 Error detection and report to higher layersndash 1048713 Multiplexing of transport channelsndash 1048713 Mapping of transport channels to physical channelsndash 1048713 Fast Close loop Power controlndash 1048713 Frequency and Time Synchronizationndash 1048713 Other responsibilities associated with transmitting and

receiving signals over the wireless mediandash Measurements

bull SIRbull Tx power Frame error rate etc

bull Physical channel is assigned a specific code

12 35

Transport amp Physical Channels

Transport Channel Physical Channel(ULDL) Dedicated Channel DCH Dedicated Physical Data Channel DPDCH

Dedicated Physical Control Channel DPCCH

(UL) Random Access Channel RACH Physical random access channel PRACH

(UL) Common packet channel CPCH Physical common packet channel PCPCH

(DL) Broadcast channel BCH Primary common control physical channel P-CCPCH

(DL) Forward access channel FACH(DL) Paging channel PCH

Secondary common control physical channel S-CCPCH

(DL) Downlink shared channel DSCH Physical downlink shared channel PDSCH

Signaling physical channels

Synchronization channel SCHCommon pilot channel CPICHAcquisition indication channel AICHPaging indication channel PICHCPCH Status indication channel CSICHCollision detectionChannel assignment indicator channel CDCA-ICH

12 36

UMTS FDD frame structure

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 37

MAC Layer

bull The MAC layer offers Data transfer to RLC and higher layers

bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically

bit rate within a predefined set per information unit delivered to the physical layer

ndash Service multiplexing on RACH FACH and dedicated channels

ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling

ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements

12 38

Physical Layer

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 39

RRC Layerbull The RRC layer offers the core network the following

servicesndash General control service which is used as an information

broadcast servicendash Notification service which is used for paging and

notification of a selected UEsndash Dedicated control service which is used for

establishmentrelease of a connection and transfer of messages using the connection

bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover

admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection

12 40

RLC Layer

bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is

appended to the information unit received from the higher layer

ndash Assured and un assured data transferbull The RLC layer comprises the following functions

ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the

WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the

control plane)ndash Duplicate detectionndash Flow controlndash Ciphering

12 41

RLC Layer-Modesbull Transparent-TM

ndash No header attachedndash SARndash SDU discard

bull Delete SDU if not sent before timer expiresndash Used for

bull Voicebull Some signaling

bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability

bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat

12 42

RLC Layer

From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the

UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

12 43

UE-Call states

bull Designed to ndash Take advantage of bursty nature of

datandash Save batter powerndash Maintains logical session and tracks

mobility but when appropriatendash releases dedicated resources to

increase overall capacityndash asleeps the UE

12 44

UE-Call states

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 45

UE-Call states

bull Idle modendash No active sessionndash UE monitors

Paging CHndash Sleeps between

paging cycles

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 46

UE-Call states

bull CELL_DCH state (Dedicated)ndash A dedicated physical

channel is allocated to the UE in uplink and downlink

ndash The UE is known on cell level according to its current active set

ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE

ndash Call typesbull Circuit Switched always in

this statebull Packet Switched in this

state if transferring large volume of data

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 47

UE-Call states

bull CELL_FACH state(Forward Access Ch)

ndash No dedicated physical channel is allocated to the UE

ndash The UE continuously monitors a FACH in the downlink

ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel

ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update

ndash Radio not put to sleepndash For packet switched sessions

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 48

UE-Call states

bull CELL_PCH state (Paging Ch)ndash No dedicated physical

channel is allocated to the UE

ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash Sleep between pagesndash A logical session is still upndash The position of the UE is

known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 49

UE-Call states

bull URA_PCH State ndash No dedicated channel is

allocated to the UEndash The UE selects a PCH with

the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state

ndash Similar to CELL_PCH state only the at the URA level

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 50

Power Control-PC

bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to

ensure that there is enough power for mobiles at the cell edge

bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control

commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command

ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break

12 51

Power Control

bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss

by means of a downlink beacon signalndash Provide a coarse initial power setting of

the mobile at the beginning of a connection

ndash Apply only prior to initiating the transmission on RACH or CPCH

12 52

Packet Access in WCDMA

bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection

bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared

bull RNC can decide when and how to send packets based on type of packet traffic

ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech

ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video

ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing

ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail

bull RNC can assign a packet to a specific channel

Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 53

Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the

downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft

handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts

bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts

bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink

orthogonal code is reserved according to maximum bit rate

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 54

Packet Access in WCDMA

bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner

bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer

bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate

bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and

bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 55

Packet Access in WCDMA

bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased

bull Advantagesndash resources are in full usage due to longer transmission

timendash small variation in interference levelndash longer uplink range due to lower bit rate

bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 56

Packet Access in WCDMA

bull Time division is normally used with shared channels and code division is normally used with dedicated channels

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 57

Packet Access in WCDMA

bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users

could be based on required transmission powerbull Users close to the BS requires less

transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate

bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput

bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 58

HSDPA amp Enhance Uplink

bull HSDPA = High Speed Downlink Packet Access

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 59

HSDPA amp Enhance Uplink

bull Remember it is better (more efficient) to have a large number of users sharing a single server

bull This lead to a desire to have fast allocation of shared resources

bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code

bull Uplink resourcesndash Interference at the BS

bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)

bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)

12 60

HSDPA amp Enhance Uplink

bull UTRAN Architecture with HSDPA and enhanced uplink

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 61

HSDPA amp Enhance Uplink

bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK

modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and

coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function

moved to Node-B (WCDMA packet scheduling was done in the RNC)

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 62

HSDPA amp Enhance Uplink

bull Gain in Performance

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 63

HSDPA

bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to

individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes

bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)

12 64

HSDPA

bull New frame structurendash Five subframesW-CDMA

framendash User data can be

assigned on a subframe basis

ndash System can adjust in 2ms

ndash Each subframe is a transmission time interval (TTI) = 2ms

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 65

HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared

resource is also in the time domain

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 66

HSDPA

bull Another view

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

Spreading Code

12 67

HSDPAbull Link Adaptation

ndash Remember the fast power control is commonly used to

bull Maintain constant EnergyNoise ratiobull Reduce effect of fading

ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant

EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 68

HSDPA

ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)

ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum

bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user

bull 1 ndash 2 Mbs closer to achievable under real conditions

12 69

HSDPA

bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE

bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms

bull CQI (0-30) each mapping into a modulation SF etc

bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression

bull

12 70

HSDPA

bull Schedulingndash The scheduler decides which user

should get access to each TTI ndash CQI provides input into a Scheduler

bull Proportional Fair (PF) Scheduler can be uses

bull Implementation Specific

12 71

HSDPA

bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number

of spreading codes limits rate not power so likely receive first transmission

ndash At greater distances move from BS see more errors IR will require additional transmission but not many

ndash HARQ only retransmit upon an ACK or NACK

12 72

HSDPA

From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007

12 73

HSDPA

bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2

ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent

Scheduling

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 28

UMTS Architecture

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 29

UMTS Architecture

bull User equipment-UEndash UMTS Subscriber Identity Module ndashUSIMndash Mobile Equipment- cell phone

bull UMTS Terrestrial Radio Access Networkndash Radio Network Subsystem

bull Node B- BSndash Transceiverndash Rate adaptationndash Radio resource managementndash Power control

12 30

UMTS Architecture

bull Radio Network Controller ndash RNCndash Radio access controlndash Connection controlndash Load congestion and admission controlndash Code allocation

ndash Core Networkbull MSCbull VLRbull HLRbull Gateway MSC ndash GMSC

ndash Supports circuit switched connectionsbull Serving GRPS Support Node ndash SGPRS

ndash Logical interface to UTRAN for packet transportraquo Session managementraquo Logical link management

bull Gateway GPRS Support Node ndash GGSNndash Supports packet switched transportndash This is an IP router

12 31

UMTS Protocol Architecture - User Plane

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

FP= Framing Protocol GTP-U= GPRS Tunneling Protocol-UserPDCP =Packet Data convergence Protocol

12 32

UMTS Protocol Stack

bull Radio Resource Control-RRC

bull Broadcastmulitcast control- BMC

bull Packet Data convergence Protocol- PDCPndash Header

compression

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

12 33

Packet SAR

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

12 34

Physical Layerbull The physical layer offers information transfer services to

the MAC layer These services are denoted as Transport channels (TrChrsquos) There are also Physical channels

bull Physical layer comprises following functionsndash 1048713 Various handover functionsndash 1048713 Error detection and report to higher layersndash 1048713 Multiplexing of transport channelsndash 1048713 Mapping of transport channels to physical channelsndash 1048713 Fast Close loop Power controlndash 1048713 Frequency and Time Synchronizationndash 1048713 Other responsibilities associated with transmitting and

receiving signals over the wireless mediandash Measurements

bull SIRbull Tx power Frame error rate etc

bull Physical channel is assigned a specific code

12 35

Transport amp Physical Channels

Transport Channel Physical Channel(ULDL) Dedicated Channel DCH Dedicated Physical Data Channel DPDCH

Dedicated Physical Control Channel DPCCH

(UL) Random Access Channel RACH Physical random access channel PRACH

(UL) Common packet channel CPCH Physical common packet channel PCPCH

(DL) Broadcast channel BCH Primary common control physical channel P-CCPCH

(DL) Forward access channel FACH(DL) Paging channel PCH

Secondary common control physical channel S-CCPCH

(DL) Downlink shared channel DSCH Physical downlink shared channel PDSCH

Signaling physical channels

Synchronization channel SCHCommon pilot channel CPICHAcquisition indication channel AICHPaging indication channel PICHCPCH Status indication channel CSICHCollision detectionChannel assignment indicator channel CDCA-ICH

12 36

UMTS FDD frame structure

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 37

MAC Layer

bull The MAC layer offers Data transfer to RLC and higher layers

bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically

bit rate within a predefined set per information unit delivered to the physical layer

ndash Service multiplexing on RACH FACH and dedicated channels

ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling

ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements

12 38

Physical Layer

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 39

RRC Layerbull The RRC layer offers the core network the following

servicesndash General control service which is used as an information

broadcast servicendash Notification service which is used for paging and

notification of a selected UEsndash Dedicated control service which is used for

establishmentrelease of a connection and transfer of messages using the connection

bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover

admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection

12 40

RLC Layer

bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is

appended to the information unit received from the higher layer

ndash Assured and un assured data transferbull The RLC layer comprises the following functions

ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the

WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the

control plane)ndash Duplicate detectionndash Flow controlndash Ciphering

12 41

RLC Layer-Modesbull Transparent-TM

ndash No header attachedndash SARndash SDU discard

bull Delete SDU if not sent before timer expiresndash Used for

bull Voicebull Some signaling

bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability

bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat

12 42

RLC Layer

From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the

UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

12 43

UE-Call states

bull Designed to ndash Take advantage of bursty nature of

datandash Save batter powerndash Maintains logical session and tracks

mobility but when appropriatendash releases dedicated resources to

increase overall capacityndash asleeps the UE

12 44

UE-Call states

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 45

UE-Call states

bull Idle modendash No active sessionndash UE monitors

Paging CHndash Sleeps between

paging cycles

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 46

UE-Call states

bull CELL_DCH state (Dedicated)ndash A dedicated physical

channel is allocated to the UE in uplink and downlink

ndash The UE is known on cell level according to its current active set

ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE

ndash Call typesbull Circuit Switched always in

this statebull Packet Switched in this

state if transferring large volume of data

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 47

UE-Call states

bull CELL_FACH state(Forward Access Ch)

ndash No dedicated physical channel is allocated to the UE

ndash The UE continuously monitors a FACH in the downlink

ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel

ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update

ndash Radio not put to sleepndash For packet switched sessions

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 48

UE-Call states

bull CELL_PCH state (Paging Ch)ndash No dedicated physical

channel is allocated to the UE

ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash Sleep between pagesndash A logical session is still upndash The position of the UE is

known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 49

UE-Call states

bull URA_PCH State ndash No dedicated channel is

allocated to the UEndash The UE selects a PCH with

the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state

ndash Similar to CELL_PCH state only the at the URA level

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 50

Power Control-PC

bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to

ensure that there is enough power for mobiles at the cell edge

bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control

commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command

ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break

12 51

Power Control

bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss

by means of a downlink beacon signalndash Provide a coarse initial power setting of

the mobile at the beginning of a connection

ndash Apply only prior to initiating the transmission on RACH or CPCH

12 52

Packet Access in WCDMA

bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection

bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared

bull RNC can decide when and how to send packets based on type of packet traffic

ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech

ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video

ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing

ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail

bull RNC can assign a packet to a specific channel

Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 53

Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the

downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft

handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts

bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts

bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink

orthogonal code is reserved according to maximum bit rate

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 54

Packet Access in WCDMA

bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner

bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer

bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate

bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and

bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 55

Packet Access in WCDMA

bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased

bull Advantagesndash resources are in full usage due to longer transmission

timendash small variation in interference levelndash longer uplink range due to lower bit rate

bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 56

Packet Access in WCDMA

bull Time division is normally used with shared channels and code division is normally used with dedicated channels

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 57

Packet Access in WCDMA

bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users

could be based on required transmission powerbull Users close to the BS requires less

transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate

bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput

bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 58

HSDPA amp Enhance Uplink

bull HSDPA = High Speed Downlink Packet Access

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 59

HSDPA amp Enhance Uplink

bull Remember it is better (more efficient) to have a large number of users sharing a single server

bull This lead to a desire to have fast allocation of shared resources

bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code

bull Uplink resourcesndash Interference at the BS

bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)

bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)

12 60

HSDPA amp Enhance Uplink

bull UTRAN Architecture with HSDPA and enhanced uplink

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 61

HSDPA amp Enhance Uplink

bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK

modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and

coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function

moved to Node-B (WCDMA packet scheduling was done in the RNC)

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 62

HSDPA amp Enhance Uplink

bull Gain in Performance

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 63

HSDPA

bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to

individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes

bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)

12 64

HSDPA

bull New frame structurendash Five subframesW-CDMA

framendash User data can be

assigned on a subframe basis

ndash System can adjust in 2ms

ndash Each subframe is a transmission time interval (TTI) = 2ms

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 65

HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared

resource is also in the time domain

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 66

HSDPA

bull Another view

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

Spreading Code

12 67

HSDPAbull Link Adaptation

ndash Remember the fast power control is commonly used to

bull Maintain constant EnergyNoise ratiobull Reduce effect of fading

ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant

EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 68

HSDPA

ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)

ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum

bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user

bull 1 ndash 2 Mbs closer to achievable under real conditions

12 69

HSDPA

bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE

bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms

bull CQI (0-30) each mapping into a modulation SF etc

bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression

bull

12 70

HSDPA

bull Schedulingndash The scheduler decides which user

should get access to each TTI ndash CQI provides input into a Scheduler

bull Proportional Fair (PF) Scheduler can be uses

bull Implementation Specific

12 71

HSDPA

bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number

of spreading codes limits rate not power so likely receive first transmission

ndash At greater distances move from BS see more errors IR will require additional transmission but not many

ndash HARQ only retransmit upon an ACK or NACK

12 72

HSDPA

From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007

12 73

HSDPA

bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2

ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent

Scheduling

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 29

UMTS Architecture

bull User equipment-UEndash UMTS Subscriber Identity Module ndashUSIMndash Mobile Equipment- cell phone

bull UMTS Terrestrial Radio Access Networkndash Radio Network Subsystem

bull Node B- BSndash Transceiverndash Rate adaptationndash Radio resource managementndash Power control

12 30

UMTS Architecture

bull Radio Network Controller ndash RNCndash Radio access controlndash Connection controlndash Load congestion and admission controlndash Code allocation

ndash Core Networkbull MSCbull VLRbull HLRbull Gateway MSC ndash GMSC

ndash Supports circuit switched connectionsbull Serving GRPS Support Node ndash SGPRS

ndash Logical interface to UTRAN for packet transportraquo Session managementraquo Logical link management

bull Gateway GPRS Support Node ndash GGSNndash Supports packet switched transportndash This is an IP router

12 31

UMTS Protocol Architecture - User Plane

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

FP= Framing Protocol GTP-U= GPRS Tunneling Protocol-UserPDCP =Packet Data convergence Protocol

12 32

UMTS Protocol Stack

bull Radio Resource Control-RRC

bull Broadcastmulitcast control- BMC

bull Packet Data convergence Protocol- PDCPndash Header

compression

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

12 33

Packet SAR

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

12 34

Physical Layerbull The physical layer offers information transfer services to

the MAC layer These services are denoted as Transport channels (TrChrsquos) There are also Physical channels

bull Physical layer comprises following functionsndash 1048713 Various handover functionsndash 1048713 Error detection and report to higher layersndash 1048713 Multiplexing of transport channelsndash 1048713 Mapping of transport channels to physical channelsndash 1048713 Fast Close loop Power controlndash 1048713 Frequency and Time Synchronizationndash 1048713 Other responsibilities associated with transmitting and

receiving signals over the wireless mediandash Measurements

bull SIRbull Tx power Frame error rate etc

bull Physical channel is assigned a specific code

12 35

Transport amp Physical Channels

Transport Channel Physical Channel(ULDL) Dedicated Channel DCH Dedicated Physical Data Channel DPDCH

Dedicated Physical Control Channel DPCCH

(UL) Random Access Channel RACH Physical random access channel PRACH

(UL) Common packet channel CPCH Physical common packet channel PCPCH

(DL) Broadcast channel BCH Primary common control physical channel P-CCPCH

(DL) Forward access channel FACH(DL) Paging channel PCH

Secondary common control physical channel S-CCPCH

(DL) Downlink shared channel DSCH Physical downlink shared channel PDSCH

Signaling physical channels

Synchronization channel SCHCommon pilot channel CPICHAcquisition indication channel AICHPaging indication channel PICHCPCH Status indication channel CSICHCollision detectionChannel assignment indicator channel CDCA-ICH

12 36

UMTS FDD frame structure

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 37

MAC Layer

bull The MAC layer offers Data transfer to RLC and higher layers

bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically

bit rate within a predefined set per information unit delivered to the physical layer

ndash Service multiplexing on RACH FACH and dedicated channels

ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling

ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements

12 38

Physical Layer

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 39

RRC Layerbull The RRC layer offers the core network the following

servicesndash General control service which is used as an information

broadcast servicendash Notification service which is used for paging and

notification of a selected UEsndash Dedicated control service which is used for

establishmentrelease of a connection and transfer of messages using the connection

bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover

admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection

12 40

RLC Layer

bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is

appended to the information unit received from the higher layer

ndash Assured and un assured data transferbull The RLC layer comprises the following functions

ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the

WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the

control plane)ndash Duplicate detectionndash Flow controlndash Ciphering

12 41

RLC Layer-Modesbull Transparent-TM

ndash No header attachedndash SARndash SDU discard

bull Delete SDU if not sent before timer expiresndash Used for

bull Voicebull Some signaling

bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability

bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat

12 42

RLC Layer

From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the

UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

12 43

UE-Call states

bull Designed to ndash Take advantage of bursty nature of

datandash Save batter powerndash Maintains logical session and tracks

mobility but when appropriatendash releases dedicated resources to

increase overall capacityndash asleeps the UE

12 44

UE-Call states

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 45

UE-Call states

bull Idle modendash No active sessionndash UE monitors

Paging CHndash Sleeps between

paging cycles

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 46

UE-Call states

bull CELL_DCH state (Dedicated)ndash A dedicated physical

channel is allocated to the UE in uplink and downlink

ndash The UE is known on cell level according to its current active set

ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE

ndash Call typesbull Circuit Switched always in

this statebull Packet Switched in this

state if transferring large volume of data

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 47

UE-Call states

bull CELL_FACH state(Forward Access Ch)

ndash No dedicated physical channel is allocated to the UE

ndash The UE continuously monitors a FACH in the downlink

ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel

ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update

ndash Radio not put to sleepndash For packet switched sessions

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 48

UE-Call states

bull CELL_PCH state (Paging Ch)ndash No dedicated physical

channel is allocated to the UE

ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash Sleep between pagesndash A logical session is still upndash The position of the UE is

known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 49

UE-Call states

bull URA_PCH State ndash No dedicated channel is

allocated to the UEndash The UE selects a PCH with

the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state

ndash Similar to CELL_PCH state only the at the URA level

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 50

Power Control-PC

bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to

ensure that there is enough power for mobiles at the cell edge

bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control

commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command

ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break

12 51

Power Control

bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss

by means of a downlink beacon signalndash Provide a coarse initial power setting of

the mobile at the beginning of a connection

ndash Apply only prior to initiating the transmission on RACH or CPCH

12 52

Packet Access in WCDMA

bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection

bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared

bull RNC can decide when and how to send packets based on type of packet traffic

ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech

ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video

ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing

ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail

bull RNC can assign a packet to a specific channel

Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 53

Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the

downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft

handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts

bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts

bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink

orthogonal code is reserved according to maximum bit rate

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 54

Packet Access in WCDMA

bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner

bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer

bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate

bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and

bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 55

Packet Access in WCDMA

bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased

bull Advantagesndash resources are in full usage due to longer transmission

timendash small variation in interference levelndash longer uplink range due to lower bit rate

bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 56

Packet Access in WCDMA

bull Time division is normally used with shared channels and code division is normally used with dedicated channels

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 57

Packet Access in WCDMA

bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users

could be based on required transmission powerbull Users close to the BS requires less

transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate

bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput

bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 58

HSDPA amp Enhance Uplink

bull HSDPA = High Speed Downlink Packet Access

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 59

HSDPA amp Enhance Uplink

bull Remember it is better (more efficient) to have a large number of users sharing a single server

bull This lead to a desire to have fast allocation of shared resources

bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code

bull Uplink resourcesndash Interference at the BS

bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)

bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)

12 60

HSDPA amp Enhance Uplink

bull UTRAN Architecture with HSDPA and enhanced uplink

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 61

HSDPA amp Enhance Uplink

bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK

modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and

coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function

moved to Node-B (WCDMA packet scheduling was done in the RNC)

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 62

HSDPA amp Enhance Uplink

bull Gain in Performance

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 63

HSDPA

bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to

individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes

bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)

12 64

HSDPA

bull New frame structurendash Five subframesW-CDMA

framendash User data can be

assigned on a subframe basis

ndash System can adjust in 2ms

ndash Each subframe is a transmission time interval (TTI) = 2ms

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 65

HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared

resource is also in the time domain

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 66

HSDPA

bull Another view

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

Spreading Code

12 67

HSDPAbull Link Adaptation

ndash Remember the fast power control is commonly used to

bull Maintain constant EnergyNoise ratiobull Reduce effect of fading

ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant

EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 68

HSDPA

ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)

ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum

bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user

bull 1 ndash 2 Mbs closer to achievable under real conditions

12 69

HSDPA

bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE

bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms

bull CQI (0-30) each mapping into a modulation SF etc

bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression

bull

12 70

HSDPA

bull Schedulingndash The scheduler decides which user

should get access to each TTI ndash CQI provides input into a Scheduler

bull Proportional Fair (PF) Scheduler can be uses

bull Implementation Specific

12 71

HSDPA

bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number

of spreading codes limits rate not power so likely receive first transmission

ndash At greater distances move from BS see more errors IR will require additional transmission but not many

ndash HARQ only retransmit upon an ACK or NACK

12 72

HSDPA

From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007

12 73

HSDPA

bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2

ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent

Scheduling

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 30

UMTS Architecture

bull Radio Network Controller ndash RNCndash Radio access controlndash Connection controlndash Load congestion and admission controlndash Code allocation

ndash Core Networkbull MSCbull VLRbull HLRbull Gateway MSC ndash GMSC

ndash Supports circuit switched connectionsbull Serving GRPS Support Node ndash SGPRS

ndash Logical interface to UTRAN for packet transportraquo Session managementraquo Logical link management

bull Gateway GPRS Support Node ndash GGSNndash Supports packet switched transportndash This is an IP router

12 31

UMTS Protocol Architecture - User Plane

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

FP= Framing Protocol GTP-U= GPRS Tunneling Protocol-UserPDCP =Packet Data convergence Protocol

12 32

UMTS Protocol Stack

bull Radio Resource Control-RRC

bull Broadcastmulitcast control- BMC

bull Packet Data convergence Protocol- PDCPndash Header

compression

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

12 33

Packet SAR

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

12 34

Physical Layerbull The physical layer offers information transfer services to

the MAC layer These services are denoted as Transport channels (TrChrsquos) There are also Physical channels

bull Physical layer comprises following functionsndash 1048713 Various handover functionsndash 1048713 Error detection and report to higher layersndash 1048713 Multiplexing of transport channelsndash 1048713 Mapping of transport channels to physical channelsndash 1048713 Fast Close loop Power controlndash 1048713 Frequency and Time Synchronizationndash 1048713 Other responsibilities associated with transmitting and

receiving signals over the wireless mediandash Measurements

bull SIRbull Tx power Frame error rate etc

bull Physical channel is assigned a specific code

12 35

Transport amp Physical Channels

Transport Channel Physical Channel(ULDL) Dedicated Channel DCH Dedicated Physical Data Channel DPDCH

Dedicated Physical Control Channel DPCCH

(UL) Random Access Channel RACH Physical random access channel PRACH

(UL) Common packet channel CPCH Physical common packet channel PCPCH

(DL) Broadcast channel BCH Primary common control physical channel P-CCPCH

(DL) Forward access channel FACH(DL) Paging channel PCH

Secondary common control physical channel S-CCPCH

(DL) Downlink shared channel DSCH Physical downlink shared channel PDSCH

Signaling physical channels

Synchronization channel SCHCommon pilot channel CPICHAcquisition indication channel AICHPaging indication channel PICHCPCH Status indication channel CSICHCollision detectionChannel assignment indicator channel CDCA-ICH

12 36

UMTS FDD frame structure

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 37

MAC Layer

bull The MAC layer offers Data transfer to RLC and higher layers

bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically

bit rate within a predefined set per information unit delivered to the physical layer

ndash Service multiplexing on RACH FACH and dedicated channels

ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling

ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements

12 38

Physical Layer

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 39

RRC Layerbull The RRC layer offers the core network the following

servicesndash General control service which is used as an information

broadcast servicendash Notification service which is used for paging and

notification of a selected UEsndash Dedicated control service which is used for

establishmentrelease of a connection and transfer of messages using the connection

bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover

admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection

12 40

RLC Layer

bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is

appended to the information unit received from the higher layer

ndash Assured and un assured data transferbull The RLC layer comprises the following functions

ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the

WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the

control plane)ndash Duplicate detectionndash Flow controlndash Ciphering

12 41

RLC Layer-Modesbull Transparent-TM

ndash No header attachedndash SARndash SDU discard

bull Delete SDU if not sent before timer expiresndash Used for

bull Voicebull Some signaling

bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability

bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat

12 42

RLC Layer

From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the

UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

12 43

UE-Call states

bull Designed to ndash Take advantage of bursty nature of

datandash Save batter powerndash Maintains logical session and tracks

mobility but when appropriatendash releases dedicated resources to

increase overall capacityndash asleeps the UE

12 44

UE-Call states

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 45

UE-Call states

bull Idle modendash No active sessionndash UE monitors

Paging CHndash Sleeps between

paging cycles

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 46

UE-Call states

bull CELL_DCH state (Dedicated)ndash A dedicated physical

channel is allocated to the UE in uplink and downlink

ndash The UE is known on cell level according to its current active set

ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE

ndash Call typesbull Circuit Switched always in

this statebull Packet Switched in this

state if transferring large volume of data

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 47

UE-Call states

bull CELL_FACH state(Forward Access Ch)

ndash No dedicated physical channel is allocated to the UE

ndash The UE continuously monitors a FACH in the downlink

ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel

ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update

ndash Radio not put to sleepndash For packet switched sessions

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 48

UE-Call states

bull CELL_PCH state (Paging Ch)ndash No dedicated physical

channel is allocated to the UE

ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash Sleep between pagesndash A logical session is still upndash The position of the UE is

known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 49

UE-Call states

bull URA_PCH State ndash No dedicated channel is

allocated to the UEndash The UE selects a PCH with

the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state

ndash Similar to CELL_PCH state only the at the URA level

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 50

Power Control-PC

bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to

ensure that there is enough power for mobiles at the cell edge

bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control

commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command

ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break

12 51

Power Control

bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss

by means of a downlink beacon signalndash Provide a coarse initial power setting of

the mobile at the beginning of a connection

ndash Apply only prior to initiating the transmission on RACH or CPCH

12 52

Packet Access in WCDMA

bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection

bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared

bull RNC can decide when and how to send packets based on type of packet traffic

ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech

ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video

ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing

ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail

bull RNC can assign a packet to a specific channel

Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 53

Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the

downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft

handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts

bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts

bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink

orthogonal code is reserved according to maximum bit rate

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 54

Packet Access in WCDMA

bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner

bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer

bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate

bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and

bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 55

Packet Access in WCDMA

bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased

bull Advantagesndash resources are in full usage due to longer transmission

timendash small variation in interference levelndash longer uplink range due to lower bit rate

bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 56

Packet Access in WCDMA

bull Time division is normally used with shared channels and code division is normally used with dedicated channels

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 57

Packet Access in WCDMA

bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users

could be based on required transmission powerbull Users close to the BS requires less

transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate

bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput

bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 58

HSDPA amp Enhance Uplink

bull HSDPA = High Speed Downlink Packet Access

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 59

HSDPA amp Enhance Uplink

bull Remember it is better (more efficient) to have a large number of users sharing a single server

bull This lead to a desire to have fast allocation of shared resources

bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code

bull Uplink resourcesndash Interference at the BS

bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)

bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)

12 60

HSDPA amp Enhance Uplink

bull UTRAN Architecture with HSDPA and enhanced uplink

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 61

HSDPA amp Enhance Uplink

bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK

modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and

coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function

moved to Node-B (WCDMA packet scheduling was done in the RNC)

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 62

HSDPA amp Enhance Uplink

bull Gain in Performance

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 63

HSDPA

bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to

individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes

bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)

12 64

HSDPA

bull New frame structurendash Five subframesW-CDMA

framendash User data can be

assigned on a subframe basis

ndash System can adjust in 2ms

ndash Each subframe is a transmission time interval (TTI) = 2ms

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 65

HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared

resource is also in the time domain

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 66

HSDPA

bull Another view

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

Spreading Code

12 67

HSDPAbull Link Adaptation

ndash Remember the fast power control is commonly used to

bull Maintain constant EnergyNoise ratiobull Reduce effect of fading

ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant

EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 68

HSDPA

ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)

ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum

bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user

bull 1 ndash 2 Mbs closer to achievable under real conditions

12 69

HSDPA

bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE

bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms

bull CQI (0-30) each mapping into a modulation SF etc

bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression

bull

12 70

HSDPA

bull Schedulingndash The scheduler decides which user

should get access to each TTI ndash CQI provides input into a Scheduler

bull Proportional Fair (PF) Scheduler can be uses

bull Implementation Specific

12 71

HSDPA

bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number

of spreading codes limits rate not power so likely receive first transmission

ndash At greater distances move from BS see more errors IR will require additional transmission but not many

ndash HARQ only retransmit upon an ACK or NACK

12 72

HSDPA

From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007

12 73

HSDPA

bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2

ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent

Scheduling

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 31

UMTS Protocol Architecture - User Plane

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

FP= Framing Protocol GTP-U= GPRS Tunneling Protocol-UserPDCP =Packet Data convergence Protocol

12 32

UMTS Protocol Stack

bull Radio Resource Control-RRC

bull Broadcastmulitcast control- BMC

bull Packet Data convergence Protocol- PDCPndash Header

compression

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

12 33

Packet SAR

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

12 34

Physical Layerbull The physical layer offers information transfer services to

the MAC layer These services are denoted as Transport channels (TrChrsquos) There are also Physical channels

bull Physical layer comprises following functionsndash 1048713 Various handover functionsndash 1048713 Error detection and report to higher layersndash 1048713 Multiplexing of transport channelsndash 1048713 Mapping of transport channels to physical channelsndash 1048713 Fast Close loop Power controlndash 1048713 Frequency and Time Synchronizationndash 1048713 Other responsibilities associated with transmitting and

receiving signals over the wireless mediandash Measurements

bull SIRbull Tx power Frame error rate etc

bull Physical channel is assigned a specific code

12 35

Transport amp Physical Channels

Transport Channel Physical Channel(ULDL) Dedicated Channel DCH Dedicated Physical Data Channel DPDCH

Dedicated Physical Control Channel DPCCH

(UL) Random Access Channel RACH Physical random access channel PRACH

(UL) Common packet channel CPCH Physical common packet channel PCPCH

(DL) Broadcast channel BCH Primary common control physical channel P-CCPCH

(DL) Forward access channel FACH(DL) Paging channel PCH

Secondary common control physical channel S-CCPCH

(DL) Downlink shared channel DSCH Physical downlink shared channel PDSCH

Signaling physical channels

Synchronization channel SCHCommon pilot channel CPICHAcquisition indication channel AICHPaging indication channel PICHCPCH Status indication channel CSICHCollision detectionChannel assignment indicator channel CDCA-ICH

12 36

UMTS FDD frame structure

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 37

MAC Layer

bull The MAC layer offers Data transfer to RLC and higher layers

bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically

bit rate within a predefined set per information unit delivered to the physical layer

ndash Service multiplexing on RACH FACH and dedicated channels

ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling

ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements

12 38

Physical Layer

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 39

RRC Layerbull The RRC layer offers the core network the following

servicesndash General control service which is used as an information

broadcast servicendash Notification service which is used for paging and

notification of a selected UEsndash Dedicated control service which is used for

establishmentrelease of a connection and transfer of messages using the connection

bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover

admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection

12 40

RLC Layer

bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is

appended to the information unit received from the higher layer

ndash Assured and un assured data transferbull The RLC layer comprises the following functions

ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the

WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the

control plane)ndash Duplicate detectionndash Flow controlndash Ciphering

12 41

RLC Layer-Modesbull Transparent-TM

ndash No header attachedndash SARndash SDU discard

bull Delete SDU if not sent before timer expiresndash Used for

bull Voicebull Some signaling

bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability

bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat

12 42

RLC Layer

From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the

UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

12 43

UE-Call states

bull Designed to ndash Take advantage of bursty nature of

datandash Save batter powerndash Maintains logical session and tracks

mobility but when appropriatendash releases dedicated resources to

increase overall capacityndash asleeps the UE

12 44

UE-Call states

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 45

UE-Call states

bull Idle modendash No active sessionndash UE monitors

Paging CHndash Sleeps between

paging cycles

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 46

UE-Call states

bull CELL_DCH state (Dedicated)ndash A dedicated physical

channel is allocated to the UE in uplink and downlink

ndash The UE is known on cell level according to its current active set

ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE

ndash Call typesbull Circuit Switched always in

this statebull Packet Switched in this

state if transferring large volume of data

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 47

UE-Call states

bull CELL_FACH state(Forward Access Ch)

ndash No dedicated physical channel is allocated to the UE

ndash The UE continuously monitors a FACH in the downlink

ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel

ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update

ndash Radio not put to sleepndash For packet switched sessions

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 48

UE-Call states

bull CELL_PCH state (Paging Ch)ndash No dedicated physical

channel is allocated to the UE

ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash Sleep between pagesndash A logical session is still upndash The position of the UE is

known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 49

UE-Call states

bull URA_PCH State ndash No dedicated channel is

allocated to the UEndash The UE selects a PCH with

the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state

ndash Similar to CELL_PCH state only the at the URA level

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 50

Power Control-PC

bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to

ensure that there is enough power for mobiles at the cell edge

bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control

commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command

ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break

12 51

Power Control

bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss

by means of a downlink beacon signalndash Provide a coarse initial power setting of

the mobile at the beginning of a connection

ndash Apply only prior to initiating the transmission on RACH or CPCH

12 52

Packet Access in WCDMA

bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection

bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared

bull RNC can decide when and how to send packets based on type of packet traffic

ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech

ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video

ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing

ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail

bull RNC can assign a packet to a specific channel

Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 53

Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the

downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft

handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts

bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts

bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink

orthogonal code is reserved according to maximum bit rate

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 54

Packet Access in WCDMA

bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner

bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer

bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate

bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and

bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 55

Packet Access in WCDMA

bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased

bull Advantagesndash resources are in full usage due to longer transmission

timendash small variation in interference levelndash longer uplink range due to lower bit rate

bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 56

Packet Access in WCDMA

bull Time division is normally used with shared channels and code division is normally used with dedicated channels

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 57

Packet Access in WCDMA

bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users

could be based on required transmission powerbull Users close to the BS requires less

transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate

bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput

bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 58

HSDPA amp Enhance Uplink

bull HSDPA = High Speed Downlink Packet Access

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 59

HSDPA amp Enhance Uplink

bull Remember it is better (more efficient) to have a large number of users sharing a single server

bull This lead to a desire to have fast allocation of shared resources

bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code

bull Uplink resourcesndash Interference at the BS

bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)

bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)

12 60

HSDPA amp Enhance Uplink

bull UTRAN Architecture with HSDPA and enhanced uplink

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 61

HSDPA amp Enhance Uplink

bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK

modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and

coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function

moved to Node-B (WCDMA packet scheduling was done in the RNC)

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 62

HSDPA amp Enhance Uplink

bull Gain in Performance

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 63

HSDPA

bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to

individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes

bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)

12 64

HSDPA

bull New frame structurendash Five subframesW-CDMA

framendash User data can be

assigned on a subframe basis

ndash System can adjust in 2ms

ndash Each subframe is a transmission time interval (TTI) = 2ms

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 65

HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared

resource is also in the time domain

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 66

HSDPA

bull Another view

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

Spreading Code

12 67

HSDPAbull Link Adaptation

ndash Remember the fast power control is commonly used to

bull Maintain constant EnergyNoise ratiobull Reduce effect of fading

ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant

EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 68

HSDPA

ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)

ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum

bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user

bull 1 ndash 2 Mbs closer to achievable under real conditions

12 69

HSDPA

bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE

bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms

bull CQI (0-30) each mapping into a modulation SF etc

bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression

bull

12 70

HSDPA

bull Schedulingndash The scheduler decides which user

should get access to each TTI ndash CQI provides input into a Scheduler

bull Proportional Fair (PF) Scheduler can be uses

bull Implementation Specific

12 71

HSDPA

bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number

of spreading codes limits rate not power so likely receive first transmission

ndash At greater distances move from BS see more errors IR will require additional transmission but not many

ndash HARQ only retransmit upon an ACK or NACK

12 72

HSDPA

From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007

12 73

HSDPA

bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2

ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent

Scheduling

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 32

UMTS Protocol Stack

bull Radio Resource Control-RRC

bull Broadcastmulitcast control- BMC

bull Packet Data convergence Protocol- PDCPndash Header

compression

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

12 33

Packet SAR

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

12 34

Physical Layerbull The physical layer offers information transfer services to

the MAC layer These services are denoted as Transport channels (TrChrsquos) There are also Physical channels

bull Physical layer comprises following functionsndash 1048713 Various handover functionsndash 1048713 Error detection and report to higher layersndash 1048713 Multiplexing of transport channelsndash 1048713 Mapping of transport channels to physical channelsndash 1048713 Fast Close loop Power controlndash 1048713 Frequency and Time Synchronizationndash 1048713 Other responsibilities associated with transmitting and

receiving signals over the wireless mediandash Measurements

bull SIRbull Tx power Frame error rate etc

bull Physical channel is assigned a specific code

12 35

Transport amp Physical Channels

Transport Channel Physical Channel(ULDL) Dedicated Channel DCH Dedicated Physical Data Channel DPDCH

Dedicated Physical Control Channel DPCCH

(UL) Random Access Channel RACH Physical random access channel PRACH

(UL) Common packet channel CPCH Physical common packet channel PCPCH

(DL) Broadcast channel BCH Primary common control physical channel P-CCPCH

(DL) Forward access channel FACH(DL) Paging channel PCH

Secondary common control physical channel S-CCPCH

(DL) Downlink shared channel DSCH Physical downlink shared channel PDSCH

Signaling physical channels

Synchronization channel SCHCommon pilot channel CPICHAcquisition indication channel AICHPaging indication channel PICHCPCH Status indication channel CSICHCollision detectionChannel assignment indicator channel CDCA-ICH

12 36

UMTS FDD frame structure

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 37

MAC Layer

bull The MAC layer offers Data transfer to RLC and higher layers

bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically

bit rate within a predefined set per information unit delivered to the physical layer

ndash Service multiplexing on RACH FACH and dedicated channels

ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling

ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements

12 38

Physical Layer

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 39

RRC Layerbull The RRC layer offers the core network the following

servicesndash General control service which is used as an information

broadcast servicendash Notification service which is used for paging and

notification of a selected UEsndash Dedicated control service which is used for

establishmentrelease of a connection and transfer of messages using the connection

bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover

admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection

12 40

RLC Layer

bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is

appended to the information unit received from the higher layer

ndash Assured and un assured data transferbull The RLC layer comprises the following functions

ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the

WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the

control plane)ndash Duplicate detectionndash Flow controlndash Ciphering

12 41

RLC Layer-Modesbull Transparent-TM

ndash No header attachedndash SARndash SDU discard

bull Delete SDU if not sent before timer expiresndash Used for

bull Voicebull Some signaling

bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability

bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat

12 42

RLC Layer

From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the

UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

12 43

UE-Call states

bull Designed to ndash Take advantage of bursty nature of

datandash Save batter powerndash Maintains logical session and tracks

mobility but when appropriatendash releases dedicated resources to

increase overall capacityndash asleeps the UE

12 44

UE-Call states

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 45

UE-Call states

bull Idle modendash No active sessionndash UE monitors

Paging CHndash Sleeps between

paging cycles

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 46

UE-Call states

bull CELL_DCH state (Dedicated)ndash A dedicated physical

channel is allocated to the UE in uplink and downlink

ndash The UE is known on cell level according to its current active set

ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE

ndash Call typesbull Circuit Switched always in

this statebull Packet Switched in this

state if transferring large volume of data

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 47

UE-Call states

bull CELL_FACH state(Forward Access Ch)

ndash No dedicated physical channel is allocated to the UE

ndash The UE continuously monitors a FACH in the downlink

ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel

ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update

ndash Radio not put to sleepndash For packet switched sessions

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 48

UE-Call states

bull CELL_PCH state (Paging Ch)ndash No dedicated physical

channel is allocated to the UE

ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash Sleep between pagesndash A logical session is still upndash The position of the UE is

known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 49

UE-Call states

bull URA_PCH State ndash No dedicated channel is

allocated to the UEndash The UE selects a PCH with

the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state

ndash Similar to CELL_PCH state only the at the URA level

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 50

Power Control-PC

bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to

ensure that there is enough power for mobiles at the cell edge

bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control

commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command

ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break

12 51

Power Control

bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss

by means of a downlink beacon signalndash Provide a coarse initial power setting of

the mobile at the beginning of a connection

ndash Apply only prior to initiating the transmission on RACH or CPCH

12 52

Packet Access in WCDMA

bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection

bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared

bull RNC can decide when and how to send packets based on type of packet traffic

ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech

ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video

ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing

ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail

bull RNC can assign a packet to a specific channel

Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 53

Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the

downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft

handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts

bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts

bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink

orthogonal code is reserved according to maximum bit rate

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 54

Packet Access in WCDMA

bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner

bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer

bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate

bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and

bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 55

Packet Access in WCDMA

bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased

bull Advantagesndash resources are in full usage due to longer transmission

timendash small variation in interference levelndash longer uplink range due to lower bit rate

bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 56

Packet Access in WCDMA

bull Time division is normally used with shared channels and code division is normally used with dedicated channels

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 57

Packet Access in WCDMA

bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users

could be based on required transmission powerbull Users close to the BS requires less

transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate

bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput

bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 58

HSDPA amp Enhance Uplink

bull HSDPA = High Speed Downlink Packet Access

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 59

HSDPA amp Enhance Uplink

bull Remember it is better (more efficient) to have a large number of users sharing a single server

bull This lead to a desire to have fast allocation of shared resources

bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code

bull Uplink resourcesndash Interference at the BS

bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)

bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)

12 60

HSDPA amp Enhance Uplink

bull UTRAN Architecture with HSDPA and enhanced uplink

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 61

HSDPA amp Enhance Uplink

bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK

modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and

coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function

moved to Node-B (WCDMA packet scheduling was done in the RNC)

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 62

HSDPA amp Enhance Uplink

bull Gain in Performance

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 63

HSDPA

bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to

individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes

bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)

12 64

HSDPA

bull New frame structurendash Five subframesW-CDMA

framendash User data can be

assigned on a subframe basis

ndash System can adjust in 2ms

ndash Each subframe is a transmission time interval (TTI) = 2ms

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 65

HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared

resource is also in the time domain

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 66

HSDPA

bull Another view

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

Spreading Code

12 67

HSDPAbull Link Adaptation

ndash Remember the fast power control is commonly used to

bull Maintain constant EnergyNoise ratiobull Reduce effect of fading

ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant

EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 68

HSDPA

ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)

ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum

bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user

bull 1 ndash 2 Mbs closer to achievable under real conditions

12 69

HSDPA

bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE

bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms

bull CQI (0-30) each mapping into a modulation SF etc

bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression

bull

12 70

HSDPA

bull Schedulingndash The scheduler decides which user

should get access to each TTI ndash CQI provides input into a Scheduler

bull Proportional Fair (PF) Scheduler can be uses

bull Implementation Specific

12 71

HSDPA

bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number

of spreading codes limits rate not power so likely receive first transmission

ndash At greater distances move from BS see more errors IR will require additional transmission but not many

ndash HARQ only retransmit upon an ACK or NACK

12 72

HSDPA

From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007

12 73

HSDPA

bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2

ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent

Scheduling

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 33

Packet SAR

Modified from M D Yacoub Wireless Technology Protocols Standards and Techniques CRC Press 2002

12 34

Physical Layerbull The physical layer offers information transfer services to

the MAC layer These services are denoted as Transport channels (TrChrsquos) There are also Physical channels

bull Physical layer comprises following functionsndash 1048713 Various handover functionsndash 1048713 Error detection and report to higher layersndash 1048713 Multiplexing of transport channelsndash 1048713 Mapping of transport channels to physical channelsndash 1048713 Fast Close loop Power controlndash 1048713 Frequency and Time Synchronizationndash 1048713 Other responsibilities associated with transmitting and

receiving signals over the wireless mediandash Measurements

bull SIRbull Tx power Frame error rate etc

bull Physical channel is assigned a specific code

12 35

Transport amp Physical Channels

Transport Channel Physical Channel(ULDL) Dedicated Channel DCH Dedicated Physical Data Channel DPDCH

Dedicated Physical Control Channel DPCCH

(UL) Random Access Channel RACH Physical random access channel PRACH

(UL) Common packet channel CPCH Physical common packet channel PCPCH

(DL) Broadcast channel BCH Primary common control physical channel P-CCPCH

(DL) Forward access channel FACH(DL) Paging channel PCH

Secondary common control physical channel S-CCPCH

(DL) Downlink shared channel DSCH Physical downlink shared channel PDSCH

Signaling physical channels

Synchronization channel SCHCommon pilot channel CPICHAcquisition indication channel AICHPaging indication channel PICHCPCH Status indication channel CSICHCollision detectionChannel assignment indicator channel CDCA-ICH

12 36

UMTS FDD frame structure

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 37

MAC Layer

bull The MAC layer offers Data transfer to RLC and higher layers

bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically

bit rate within a predefined set per information unit delivered to the physical layer

ndash Service multiplexing on RACH FACH and dedicated channels

ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling

ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements

12 38

Physical Layer

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 39

RRC Layerbull The RRC layer offers the core network the following

servicesndash General control service which is used as an information

broadcast servicendash Notification service which is used for paging and

notification of a selected UEsndash Dedicated control service which is used for

establishmentrelease of a connection and transfer of messages using the connection

bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover

admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection

12 40

RLC Layer

bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is

appended to the information unit received from the higher layer

ndash Assured and un assured data transferbull The RLC layer comprises the following functions

ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the

WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the

control plane)ndash Duplicate detectionndash Flow controlndash Ciphering

12 41

RLC Layer-Modesbull Transparent-TM

ndash No header attachedndash SARndash SDU discard

bull Delete SDU if not sent before timer expiresndash Used for

bull Voicebull Some signaling

bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability

bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat

12 42

RLC Layer

From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the

UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

12 43

UE-Call states

bull Designed to ndash Take advantage of bursty nature of

datandash Save batter powerndash Maintains logical session and tracks

mobility but when appropriatendash releases dedicated resources to

increase overall capacityndash asleeps the UE

12 44

UE-Call states

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 45

UE-Call states

bull Idle modendash No active sessionndash UE monitors

Paging CHndash Sleeps between

paging cycles

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 46

UE-Call states

bull CELL_DCH state (Dedicated)ndash A dedicated physical

channel is allocated to the UE in uplink and downlink

ndash The UE is known on cell level according to its current active set

ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE

ndash Call typesbull Circuit Switched always in

this statebull Packet Switched in this

state if transferring large volume of data

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 47

UE-Call states

bull CELL_FACH state(Forward Access Ch)

ndash No dedicated physical channel is allocated to the UE

ndash The UE continuously monitors a FACH in the downlink

ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel

ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update

ndash Radio not put to sleepndash For packet switched sessions

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 48

UE-Call states

bull CELL_PCH state (Paging Ch)ndash No dedicated physical

channel is allocated to the UE

ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash Sleep between pagesndash A logical session is still upndash The position of the UE is

known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 49

UE-Call states

bull URA_PCH State ndash No dedicated channel is

allocated to the UEndash The UE selects a PCH with

the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state

ndash Similar to CELL_PCH state only the at the URA level

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 50

Power Control-PC

bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to

ensure that there is enough power for mobiles at the cell edge

bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control

commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command

ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break

12 51

Power Control

bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss

by means of a downlink beacon signalndash Provide a coarse initial power setting of

the mobile at the beginning of a connection

ndash Apply only prior to initiating the transmission on RACH or CPCH

12 52

Packet Access in WCDMA

bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection

bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared

bull RNC can decide when and how to send packets based on type of packet traffic

ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech

ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video

ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing

ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail

bull RNC can assign a packet to a specific channel

Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 53

Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the

downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft

handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts

bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts

bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink

orthogonal code is reserved according to maximum bit rate

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 54

Packet Access in WCDMA

bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner

bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer

bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate

bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and

bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 55

Packet Access in WCDMA

bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased

bull Advantagesndash resources are in full usage due to longer transmission

timendash small variation in interference levelndash longer uplink range due to lower bit rate

bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 56

Packet Access in WCDMA

bull Time division is normally used with shared channels and code division is normally used with dedicated channels

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 57

Packet Access in WCDMA

bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users

could be based on required transmission powerbull Users close to the BS requires less

transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate

bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput

bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 58

HSDPA amp Enhance Uplink

bull HSDPA = High Speed Downlink Packet Access

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 59

HSDPA amp Enhance Uplink

bull Remember it is better (more efficient) to have a large number of users sharing a single server

bull This lead to a desire to have fast allocation of shared resources

bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code

bull Uplink resourcesndash Interference at the BS

bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)

bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)

12 60

HSDPA amp Enhance Uplink

bull UTRAN Architecture with HSDPA and enhanced uplink

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 61

HSDPA amp Enhance Uplink

bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK

modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and

coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function

moved to Node-B (WCDMA packet scheduling was done in the RNC)

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 62

HSDPA amp Enhance Uplink

bull Gain in Performance

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 63

HSDPA

bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to

individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes

bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)

12 64

HSDPA

bull New frame structurendash Five subframesW-CDMA

framendash User data can be

assigned on a subframe basis

ndash System can adjust in 2ms

ndash Each subframe is a transmission time interval (TTI) = 2ms

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 65

HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared

resource is also in the time domain

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 66

HSDPA

bull Another view

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

Spreading Code

12 67

HSDPAbull Link Adaptation

ndash Remember the fast power control is commonly used to

bull Maintain constant EnergyNoise ratiobull Reduce effect of fading

ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant

EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 68

HSDPA

ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)

ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum

bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user

bull 1 ndash 2 Mbs closer to achievable under real conditions

12 69

HSDPA

bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE

bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms

bull CQI (0-30) each mapping into a modulation SF etc

bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression

bull

12 70

HSDPA

bull Schedulingndash The scheduler decides which user

should get access to each TTI ndash CQI provides input into a Scheduler

bull Proportional Fair (PF) Scheduler can be uses

bull Implementation Specific

12 71

HSDPA

bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number

of spreading codes limits rate not power so likely receive first transmission

ndash At greater distances move from BS see more errors IR will require additional transmission but not many

ndash HARQ only retransmit upon an ACK or NACK

12 72

HSDPA

From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007

12 73

HSDPA

bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2

ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent

Scheduling

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 34

Physical Layerbull The physical layer offers information transfer services to

the MAC layer These services are denoted as Transport channels (TrChrsquos) There are also Physical channels

bull Physical layer comprises following functionsndash 1048713 Various handover functionsndash 1048713 Error detection and report to higher layersndash 1048713 Multiplexing of transport channelsndash 1048713 Mapping of transport channels to physical channelsndash 1048713 Fast Close loop Power controlndash 1048713 Frequency and Time Synchronizationndash 1048713 Other responsibilities associated with transmitting and

receiving signals over the wireless mediandash Measurements

bull SIRbull Tx power Frame error rate etc

bull Physical channel is assigned a specific code

12 35

Transport amp Physical Channels

Transport Channel Physical Channel(ULDL) Dedicated Channel DCH Dedicated Physical Data Channel DPDCH

Dedicated Physical Control Channel DPCCH

(UL) Random Access Channel RACH Physical random access channel PRACH

(UL) Common packet channel CPCH Physical common packet channel PCPCH

(DL) Broadcast channel BCH Primary common control physical channel P-CCPCH

(DL) Forward access channel FACH(DL) Paging channel PCH

Secondary common control physical channel S-CCPCH

(DL) Downlink shared channel DSCH Physical downlink shared channel PDSCH

Signaling physical channels

Synchronization channel SCHCommon pilot channel CPICHAcquisition indication channel AICHPaging indication channel PICHCPCH Status indication channel CSICHCollision detectionChannel assignment indicator channel CDCA-ICH

12 36

UMTS FDD frame structure

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 37

MAC Layer

bull The MAC layer offers Data transfer to RLC and higher layers

bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically

bit rate within a predefined set per information unit delivered to the physical layer

ndash Service multiplexing on RACH FACH and dedicated channels

ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling

ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements

12 38

Physical Layer

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 39

RRC Layerbull The RRC layer offers the core network the following

servicesndash General control service which is used as an information

broadcast servicendash Notification service which is used for paging and

notification of a selected UEsndash Dedicated control service which is used for

establishmentrelease of a connection and transfer of messages using the connection

bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover

admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection

12 40

RLC Layer

bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is

appended to the information unit received from the higher layer

ndash Assured and un assured data transferbull The RLC layer comprises the following functions

ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the

WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the

control plane)ndash Duplicate detectionndash Flow controlndash Ciphering

12 41

RLC Layer-Modesbull Transparent-TM

ndash No header attachedndash SARndash SDU discard

bull Delete SDU if not sent before timer expiresndash Used for

bull Voicebull Some signaling

bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability

bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat

12 42

RLC Layer

From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the

UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

12 43

UE-Call states

bull Designed to ndash Take advantage of bursty nature of

datandash Save batter powerndash Maintains logical session and tracks

mobility but when appropriatendash releases dedicated resources to

increase overall capacityndash asleeps the UE

12 44

UE-Call states

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 45

UE-Call states

bull Idle modendash No active sessionndash UE monitors

Paging CHndash Sleeps between

paging cycles

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 46

UE-Call states

bull CELL_DCH state (Dedicated)ndash A dedicated physical

channel is allocated to the UE in uplink and downlink

ndash The UE is known on cell level according to its current active set

ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE

ndash Call typesbull Circuit Switched always in

this statebull Packet Switched in this

state if transferring large volume of data

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 47

UE-Call states

bull CELL_FACH state(Forward Access Ch)

ndash No dedicated physical channel is allocated to the UE

ndash The UE continuously monitors a FACH in the downlink

ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel

ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update

ndash Radio not put to sleepndash For packet switched sessions

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 48

UE-Call states

bull CELL_PCH state (Paging Ch)ndash No dedicated physical

channel is allocated to the UE

ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash Sleep between pagesndash A logical session is still upndash The position of the UE is

known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 49

UE-Call states

bull URA_PCH State ndash No dedicated channel is

allocated to the UEndash The UE selects a PCH with

the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state

ndash Similar to CELL_PCH state only the at the URA level

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 50

Power Control-PC

bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to

ensure that there is enough power for mobiles at the cell edge

bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control

commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command

ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break

12 51

Power Control

bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss

by means of a downlink beacon signalndash Provide a coarse initial power setting of

the mobile at the beginning of a connection

ndash Apply only prior to initiating the transmission on RACH or CPCH

12 52

Packet Access in WCDMA

bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection

bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared

bull RNC can decide when and how to send packets based on type of packet traffic

ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech

ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video

ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing

ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail

bull RNC can assign a packet to a specific channel

Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 53

Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the

downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft

handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts

bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts

bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink

orthogonal code is reserved according to maximum bit rate

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 54

Packet Access in WCDMA

bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner

bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer

bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate

bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and

bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 55

Packet Access in WCDMA

bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased

bull Advantagesndash resources are in full usage due to longer transmission

timendash small variation in interference levelndash longer uplink range due to lower bit rate

bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 56

Packet Access in WCDMA

bull Time division is normally used with shared channels and code division is normally used with dedicated channels

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 57

Packet Access in WCDMA

bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users

could be based on required transmission powerbull Users close to the BS requires less

transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate

bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput

bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 58

HSDPA amp Enhance Uplink

bull HSDPA = High Speed Downlink Packet Access

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 59

HSDPA amp Enhance Uplink

bull Remember it is better (more efficient) to have a large number of users sharing a single server

bull This lead to a desire to have fast allocation of shared resources

bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code

bull Uplink resourcesndash Interference at the BS

bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)

bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)

12 60

HSDPA amp Enhance Uplink

bull UTRAN Architecture with HSDPA and enhanced uplink

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 61

HSDPA amp Enhance Uplink

bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK

modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and

coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function

moved to Node-B (WCDMA packet scheduling was done in the RNC)

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 62

HSDPA amp Enhance Uplink

bull Gain in Performance

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 63

HSDPA

bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to

individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes

bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)

12 64

HSDPA

bull New frame structurendash Five subframesW-CDMA

framendash User data can be

assigned on a subframe basis

ndash System can adjust in 2ms

ndash Each subframe is a transmission time interval (TTI) = 2ms

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 65

HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared

resource is also in the time domain

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 66

HSDPA

bull Another view

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

Spreading Code

12 67

HSDPAbull Link Adaptation

ndash Remember the fast power control is commonly used to

bull Maintain constant EnergyNoise ratiobull Reduce effect of fading

ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant

EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 68

HSDPA

ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)

ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum

bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user

bull 1 ndash 2 Mbs closer to achievable under real conditions

12 69

HSDPA

bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE

bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms

bull CQI (0-30) each mapping into a modulation SF etc

bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression

bull

12 70

HSDPA

bull Schedulingndash The scheduler decides which user

should get access to each TTI ndash CQI provides input into a Scheduler

bull Proportional Fair (PF) Scheduler can be uses

bull Implementation Specific

12 71

HSDPA

bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number

of spreading codes limits rate not power so likely receive first transmission

ndash At greater distances move from BS see more errors IR will require additional transmission but not many

ndash HARQ only retransmit upon an ACK or NACK

12 72

HSDPA

From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007

12 73

HSDPA

bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2

ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent

Scheduling

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 35

Transport amp Physical Channels

Transport Channel Physical Channel(ULDL) Dedicated Channel DCH Dedicated Physical Data Channel DPDCH

Dedicated Physical Control Channel DPCCH

(UL) Random Access Channel RACH Physical random access channel PRACH

(UL) Common packet channel CPCH Physical common packet channel PCPCH

(DL) Broadcast channel BCH Primary common control physical channel P-CCPCH

(DL) Forward access channel FACH(DL) Paging channel PCH

Secondary common control physical channel S-CCPCH

(DL) Downlink shared channel DSCH Physical downlink shared channel PDSCH

Signaling physical channels

Synchronization channel SCHCommon pilot channel CPICHAcquisition indication channel AICHPaging indication channel PICHCPCH Status indication channel CSICHCollision detectionChannel assignment indicator channel CDCA-ICH

12 36

UMTS FDD frame structure

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 37

MAC Layer

bull The MAC layer offers Data transfer to RLC and higher layers

bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically

bit rate within a predefined set per information unit delivered to the physical layer

ndash Service multiplexing on RACH FACH and dedicated channels

ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling

ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements

12 38

Physical Layer

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 39

RRC Layerbull The RRC layer offers the core network the following

servicesndash General control service which is used as an information

broadcast servicendash Notification service which is used for paging and

notification of a selected UEsndash Dedicated control service which is used for

establishmentrelease of a connection and transfer of messages using the connection

bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover

admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection

12 40

RLC Layer

bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is

appended to the information unit received from the higher layer

ndash Assured and un assured data transferbull The RLC layer comprises the following functions

ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the

WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the

control plane)ndash Duplicate detectionndash Flow controlndash Ciphering

12 41

RLC Layer-Modesbull Transparent-TM

ndash No header attachedndash SARndash SDU discard

bull Delete SDU if not sent before timer expiresndash Used for

bull Voicebull Some signaling

bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability

bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat

12 42

RLC Layer

From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the

UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

12 43

UE-Call states

bull Designed to ndash Take advantage of bursty nature of

datandash Save batter powerndash Maintains logical session and tracks

mobility but when appropriatendash releases dedicated resources to

increase overall capacityndash asleeps the UE

12 44

UE-Call states

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 45

UE-Call states

bull Idle modendash No active sessionndash UE monitors

Paging CHndash Sleeps between

paging cycles

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 46

UE-Call states

bull CELL_DCH state (Dedicated)ndash A dedicated physical

channel is allocated to the UE in uplink and downlink

ndash The UE is known on cell level according to its current active set

ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE

ndash Call typesbull Circuit Switched always in

this statebull Packet Switched in this

state if transferring large volume of data

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 47

UE-Call states

bull CELL_FACH state(Forward Access Ch)

ndash No dedicated physical channel is allocated to the UE

ndash The UE continuously monitors a FACH in the downlink

ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel

ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update

ndash Radio not put to sleepndash For packet switched sessions

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 48

UE-Call states

bull CELL_PCH state (Paging Ch)ndash No dedicated physical

channel is allocated to the UE

ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash Sleep between pagesndash A logical session is still upndash The position of the UE is

known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 49

UE-Call states

bull URA_PCH State ndash No dedicated channel is

allocated to the UEndash The UE selects a PCH with

the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state

ndash Similar to CELL_PCH state only the at the URA level

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 50

Power Control-PC

bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to

ensure that there is enough power for mobiles at the cell edge

bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control

commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command

ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break

12 51

Power Control

bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss

by means of a downlink beacon signalndash Provide a coarse initial power setting of

the mobile at the beginning of a connection

ndash Apply only prior to initiating the transmission on RACH or CPCH

12 52

Packet Access in WCDMA

bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection

bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared

bull RNC can decide when and how to send packets based on type of packet traffic

ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech

ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video

ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing

ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail

bull RNC can assign a packet to a specific channel

Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 53

Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the

downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft

handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts

bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts

bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink

orthogonal code is reserved according to maximum bit rate

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 54

Packet Access in WCDMA

bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner

bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer

bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate

bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and

bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 55

Packet Access in WCDMA

bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased

bull Advantagesndash resources are in full usage due to longer transmission

timendash small variation in interference levelndash longer uplink range due to lower bit rate

bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 56

Packet Access in WCDMA

bull Time division is normally used with shared channels and code division is normally used with dedicated channels

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 57

Packet Access in WCDMA

bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users

could be based on required transmission powerbull Users close to the BS requires less

transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate

bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput

bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 58

HSDPA amp Enhance Uplink

bull HSDPA = High Speed Downlink Packet Access

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 59

HSDPA amp Enhance Uplink

bull Remember it is better (more efficient) to have a large number of users sharing a single server

bull This lead to a desire to have fast allocation of shared resources

bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code

bull Uplink resourcesndash Interference at the BS

bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)

bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)

12 60

HSDPA amp Enhance Uplink

bull UTRAN Architecture with HSDPA and enhanced uplink

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 61

HSDPA amp Enhance Uplink

bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK

modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and

coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function

moved to Node-B (WCDMA packet scheduling was done in the RNC)

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 62

HSDPA amp Enhance Uplink

bull Gain in Performance

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 63

HSDPA

bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to

individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes

bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)

12 64

HSDPA

bull New frame structurendash Five subframesW-CDMA

framendash User data can be

assigned on a subframe basis

ndash System can adjust in 2ms

ndash Each subframe is a transmission time interval (TTI) = 2ms

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 65

HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared

resource is also in the time domain

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 66

HSDPA

bull Another view

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

Spreading Code

12 67

HSDPAbull Link Adaptation

ndash Remember the fast power control is commonly used to

bull Maintain constant EnergyNoise ratiobull Reduce effect of fading

ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant

EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 68

HSDPA

ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)

ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum

bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user

bull 1 ndash 2 Mbs closer to achievable under real conditions

12 69

HSDPA

bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE

bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms

bull CQI (0-30) each mapping into a modulation SF etc

bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression

bull

12 70

HSDPA

bull Schedulingndash The scheduler decides which user

should get access to each TTI ndash CQI provides input into a Scheduler

bull Proportional Fair (PF) Scheduler can be uses

bull Implementation Specific

12 71

HSDPA

bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number

of spreading codes limits rate not power so likely receive first transmission

ndash At greater distances move from BS see more errors IR will require additional transmission but not many

ndash HARQ only retransmit upon an ACK or NACK

12 72

HSDPA

From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007

12 73

HSDPA

bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2

ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent

Scheduling

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 36

UMTS FDD frame structure

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 37

MAC Layer

bull The MAC layer offers Data transfer to RLC and higher layers

bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically

bit rate within a predefined set per information unit delivered to the physical layer

ndash Service multiplexing on RACH FACH and dedicated channels

ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling

ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements

12 38

Physical Layer

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 39

RRC Layerbull The RRC layer offers the core network the following

servicesndash General control service which is used as an information

broadcast servicendash Notification service which is used for paging and

notification of a selected UEsndash Dedicated control service which is used for

establishmentrelease of a connection and transfer of messages using the connection

bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover

admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection

12 40

RLC Layer

bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is

appended to the information unit received from the higher layer

ndash Assured and un assured data transferbull The RLC layer comprises the following functions

ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the

WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the

control plane)ndash Duplicate detectionndash Flow controlndash Ciphering

12 41

RLC Layer-Modesbull Transparent-TM

ndash No header attachedndash SARndash SDU discard

bull Delete SDU if not sent before timer expiresndash Used for

bull Voicebull Some signaling

bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability

bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat

12 42

RLC Layer

From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the

UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

12 43

UE-Call states

bull Designed to ndash Take advantage of bursty nature of

datandash Save batter powerndash Maintains logical session and tracks

mobility but when appropriatendash releases dedicated resources to

increase overall capacityndash asleeps the UE

12 44

UE-Call states

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 45

UE-Call states

bull Idle modendash No active sessionndash UE monitors

Paging CHndash Sleeps between

paging cycles

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 46

UE-Call states

bull CELL_DCH state (Dedicated)ndash A dedicated physical

channel is allocated to the UE in uplink and downlink

ndash The UE is known on cell level according to its current active set

ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE

ndash Call typesbull Circuit Switched always in

this statebull Packet Switched in this

state if transferring large volume of data

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 47

UE-Call states

bull CELL_FACH state(Forward Access Ch)

ndash No dedicated physical channel is allocated to the UE

ndash The UE continuously monitors a FACH in the downlink

ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel

ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update

ndash Radio not put to sleepndash For packet switched sessions

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 48

UE-Call states

bull CELL_PCH state (Paging Ch)ndash No dedicated physical

channel is allocated to the UE

ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash Sleep between pagesndash A logical session is still upndash The position of the UE is

known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 49

UE-Call states

bull URA_PCH State ndash No dedicated channel is

allocated to the UEndash The UE selects a PCH with

the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state

ndash Similar to CELL_PCH state only the at the URA level

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 50

Power Control-PC

bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to

ensure that there is enough power for mobiles at the cell edge

bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control

commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command

ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break

12 51

Power Control

bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss

by means of a downlink beacon signalndash Provide a coarse initial power setting of

the mobile at the beginning of a connection

ndash Apply only prior to initiating the transmission on RACH or CPCH

12 52

Packet Access in WCDMA

bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection

bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared

bull RNC can decide when and how to send packets based on type of packet traffic

ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech

ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video

ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing

ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail

bull RNC can assign a packet to a specific channel

Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 53

Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the

downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft

handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts

bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts

bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink

orthogonal code is reserved according to maximum bit rate

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 54

Packet Access in WCDMA

bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner

bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer

bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate

bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and

bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 55

Packet Access in WCDMA

bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased

bull Advantagesndash resources are in full usage due to longer transmission

timendash small variation in interference levelndash longer uplink range due to lower bit rate

bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 56

Packet Access in WCDMA

bull Time division is normally used with shared channels and code division is normally used with dedicated channels

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 57

Packet Access in WCDMA

bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users

could be based on required transmission powerbull Users close to the BS requires less

transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate

bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput

bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 58

HSDPA amp Enhance Uplink

bull HSDPA = High Speed Downlink Packet Access

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 59

HSDPA amp Enhance Uplink

bull Remember it is better (more efficient) to have a large number of users sharing a single server

bull This lead to a desire to have fast allocation of shared resources

bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code

bull Uplink resourcesndash Interference at the BS

bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)

bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)

12 60

HSDPA amp Enhance Uplink

bull UTRAN Architecture with HSDPA and enhanced uplink

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 61

HSDPA amp Enhance Uplink

bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK

modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and

coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function

moved to Node-B (WCDMA packet scheduling was done in the RNC)

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 62

HSDPA amp Enhance Uplink

bull Gain in Performance

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 63

HSDPA

bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to

individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes

bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)

12 64

HSDPA

bull New frame structurendash Five subframesW-CDMA

framendash User data can be

assigned on a subframe basis

ndash System can adjust in 2ms

ndash Each subframe is a transmission time interval (TTI) = 2ms

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 65

HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared

resource is also in the time domain

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 66

HSDPA

bull Another view

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

Spreading Code

12 67

HSDPAbull Link Adaptation

ndash Remember the fast power control is commonly used to

bull Maintain constant EnergyNoise ratiobull Reduce effect of fading

ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant

EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 68

HSDPA

ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)

ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum

bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user

bull 1 ndash 2 Mbs closer to achievable under real conditions

12 69

HSDPA

bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE

bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms

bull CQI (0-30) each mapping into a modulation SF etc

bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression

bull

12 70

HSDPA

bull Schedulingndash The scheduler decides which user

should get access to each TTI ndash CQI provides input into a Scheduler

bull Proportional Fair (PF) Scheduler can be uses

bull Implementation Specific

12 71

HSDPA

bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number

of spreading codes limits rate not power so likely receive first transmission

ndash At greater distances move from BS see more errors IR will require additional transmission but not many

ndash HARQ only retransmit upon an ACK or NACK

12 72

HSDPA

From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007

12 73

HSDPA

bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2

ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent

Scheduling

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 37

MAC Layer

bull The MAC layer offers Data transfer to RLC and higher layers

bull The MAC layer comprises the following functionsndash Selection of appropriate Transport Format (TF) basically

bit rate within a predefined set per information unit delivered to the physical layer

ndash Service multiplexing on RACH FACH and dedicated channels

ndash Priority handling between lsquodata flowsrsquo of one user as well as between data flows from several usersmdashthe latter being achieved by means of dynamic scheduling

ndash Access control on RACHndash Address control on RACH and FACHndash Contention resolution on RACHndash Traffic volume measurements

12 38

Physical Layer

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 39

RRC Layerbull The RRC layer offers the core network the following

servicesndash General control service which is used as an information

broadcast servicendash Notification service which is used for paging and

notification of a selected UEsndash Dedicated control service which is used for

establishmentrelease of a connection and transfer of messages using the connection

bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover

admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection

12 40

RLC Layer

bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is

appended to the information unit received from the higher layer

ndash Assured and un assured data transferbull The RLC layer comprises the following functions

ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the

WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the

control plane)ndash Duplicate detectionndash Flow controlndash Ciphering

12 41

RLC Layer-Modesbull Transparent-TM

ndash No header attachedndash SARndash SDU discard

bull Delete SDU if not sent before timer expiresndash Used for

bull Voicebull Some signaling

bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability

bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat

12 42

RLC Layer

From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the

UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

12 43

UE-Call states

bull Designed to ndash Take advantage of bursty nature of

datandash Save batter powerndash Maintains logical session and tracks

mobility but when appropriatendash releases dedicated resources to

increase overall capacityndash asleeps the UE

12 44

UE-Call states

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 45

UE-Call states

bull Idle modendash No active sessionndash UE monitors

Paging CHndash Sleeps between

paging cycles

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 46

UE-Call states

bull CELL_DCH state (Dedicated)ndash A dedicated physical

channel is allocated to the UE in uplink and downlink

ndash The UE is known on cell level according to its current active set

ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE

ndash Call typesbull Circuit Switched always in

this statebull Packet Switched in this

state if transferring large volume of data

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 47

UE-Call states

bull CELL_FACH state(Forward Access Ch)

ndash No dedicated physical channel is allocated to the UE

ndash The UE continuously monitors a FACH in the downlink

ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel

ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update

ndash Radio not put to sleepndash For packet switched sessions

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 48

UE-Call states

bull CELL_PCH state (Paging Ch)ndash No dedicated physical

channel is allocated to the UE

ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash Sleep between pagesndash A logical session is still upndash The position of the UE is

known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 49

UE-Call states

bull URA_PCH State ndash No dedicated channel is

allocated to the UEndash The UE selects a PCH with

the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state

ndash Similar to CELL_PCH state only the at the URA level

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 50

Power Control-PC

bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to

ensure that there is enough power for mobiles at the cell edge

bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control

commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command

ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break

12 51

Power Control

bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss

by means of a downlink beacon signalndash Provide a coarse initial power setting of

the mobile at the beginning of a connection

ndash Apply only prior to initiating the transmission on RACH or CPCH

12 52

Packet Access in WCDMA

bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection

bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared

bull RNC can decide when and how to send packets based on type of packet traffic

ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech

ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video

ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing

ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail

bull RNC can assign a packet to a specific channel

Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 53

Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the

downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft

handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts

bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts

bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink

orthogonal code is reserved according to maximum bit rate

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 54

Packet Access in WCDMA

bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner

bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer

bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate

bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and

bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 55

Packet Access in WCDMA

bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased

bull Advantagesndash resources are in full usage due to longer transmission

timendash small variation in interference levelndash longer uplink range due to lower bit rate

bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 56

Packet Access in WCDMA

bull Time division is normally used with shared channels and code division is normally used with dedicated channels

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 57

Packet Access in WCDMA

bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users

could be based on required transmission powerbull Users close to the BS requires less

transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate

bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput

bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 58

HSDPA amp Enhance Uplink

bull HSDPA = High Speed Downlink Packet Access

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 59

HSDPA amp Enhance Uplink

bull Remember it is better (more efficient) to have a large number of users sharing a single server

bull This lead to a desire to have fast allocation of shared resources

bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code

bull Uplink resourcesndash Interference at the BS

bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)

bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)

12 60

HSDPA amp Enhance Uplink

bull UTRAN Architecture with HSDPA and enhanced uplink

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 61

HSDPA amp Enhance Uplink

bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK

modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and

coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function

moved to Node-B (WCDMA packet scheduling was done in the RNC)

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 62

HSDPA amp Enhance Uplink

bull Gain in Performance

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 63

HSDPA

bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to

individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes

bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)

12 64

HSDPA

bull New frame structurendash Five subframesW-CDMA

framendash User data can be

assigned on a subframe basis

ndash System can adjust in 2ms

ndash Each subframe is a transmission time interval (TTI) = 2ms

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 65

HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared

resource is also in the time domain

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 66

HSDPA

bull Another view

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

Spreading Code

12 67

HSDPAbull Link Adaptation

ndash Remember the fast power control is commonly used to

bull Maintain constant EnergyNoise ratiobull Reduce effect of fading

ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant

EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 68

HSDPA

ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)

ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum

bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user

bull 1 ndash 2 Mbs closer to achievable under real conditions

12 69

HSDPA

bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE

bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms

bull CQI (0-30) each mapping into a modulation SF etc

bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression

bull

12 70

HSDPA

bull Schedulingndash The scheduler decides which user

should get access to each TTI ndash CQI provides input into a Scheduler

bull Proportional Fair (PF) Scheduler can be uses

bull Implementation Specific

12 71

HSDPA

bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number

of spreading codes limits rate not power so likely receive first transmission

ndash At greater distances move from BS see more errors IR will require additional transmission but not many

ndash HARQ only retransmit upon an ACK or NACK

12 72

HSDPA

From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007

12 73

HSDPA

bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2

ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent

Scheduling

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 38

Physical Layer

From Geert Heijenk wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

12 39

RRC Layerbull The RRC layer offers the core network the following

servicesndash General control service which is used as an information

broadcast servicendash Notification service which is used for paging and

notification of a selected UEsndash Dedicated control service which is used for

establishmentrelease of a connection and transfer of messages using the connection

bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover

admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection

12 40

RLC Layer

bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is

appended to the information unit received from the higher layer

ndash Assured and un assured data transferbull The RLC layer comprises the following functions

ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the

WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the

control plane)ndash Duplicate detectionndash Flow controlndash Ciphering

12 41

RLC Layer-Modesbull Transparent-TM

ndash No header attachedndash SARndash SDU discard

bull Delete SDU if not sent before timer expiresndash Used for

bull Voicebull Some signaling

bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability

bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat

12 42

RLC Layer

From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the

UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

12 43

UE-Call states

bull Designed to ndash Take advantage of bursty nature of

datandash Save batter powerndash Maintains logical session and tracks

mobility but when appropriatendash releases dedicated resources to

increase overall capacityndash asleeps the UE

12 44

UE-Call states

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 45

UE-Call states

bull Idle modendash No active sessionndash UE monitors

Paging CHndash Sleeps between

paging cycles

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 46

UE-Call states

bull CELL_DCH state (Dedicated)ndash A dedicated physical

channel is allocated to the UE in uplink and downlink

ndash The UE is known on cell level according to its current active set

ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE

ndash Call typesbull Circuit Switched always in

this statebull Packet Switched in this

state if transferring large volume of data

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 47

UE-Call states

bull CELL_FACH state(Forward Access Ch)

ndash No dedicated physical channel is allocated to the UE

ndash The UE continuously monitors a FACH in the downlink

ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel

ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update

ndash Radio not put to sleepndash For packet switched sessions

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 48

UE-Call states

bull CELL_PCH state (Paging Ch)ndash No dedicated physical

channel is allocated to the UE

ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash Sleep between pagesndash A logical session is still upndash The position of the UE is

known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 49

UE-Call states

bull URA_PCH State ndash No dedicated channel is

allocated to the UEndash The UE selects a PCH with

the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state

ndash Similar to CELL_PCH state only the at the URA level

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 50

Power Control-PC

bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to

ensure that there is enough power for mobiles at the cell edge

bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control

commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command

ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break

12 51

Power Control

bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss

by means of a downlink beacon signalndash Provide a coarse initial power setting of

the mobile at the beginning of a connection

ndash Apply only prior to initiating the transmission on RACH or CPCH

12 52

Packet Access in WCDMA

bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection

bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared

bull RNC can decide when and how to send packets based on type of packet traffic

ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech

ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video

ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing

ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail

bull RNC can assign a packet to a specific channel

Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 53

Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the

downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft

handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts

bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts

bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink

orthogonal code is reserved according to maximum bit rate

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 54

Packet Access in WCDMA

bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner

bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer

bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate

bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and

bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 55

Packet Access in WCDMA

bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased

bull Advantagesndash resources are in full usage due to longer transmission

timendash small variation in interference levelndash longer uplink range due to lower bit rate

bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 56

Packet Access in WCDMA

bull Time division is normally used with shared channels and code division is normally used with dedicated channels

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 57

Packet Access in WCDMA

bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users

could be based on required transmission powerbull Users close to the BS requires less

transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate

bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput

bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 58

HSDPA amp Enhance Uplink

bull HSDPA = High Speed Downlink Packet Access

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 59

HSDPA amp Enhance Uplink

bull Remember it is better (more efficient) to have a large number of users sharing a single server

bull This lead to a desire to have fast allocation of shared resources

bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code

bull Uplink resourcesndash Interference at the BS

bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)

bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)

12 60

HSDPA amp Enhance Uplink

bull UTRAN Architecture with HSDPA and enhanced uplink

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 61

HSDPA amp Enhance Uplink

bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK

modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and

coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function

moved to Node-B (WCDMA packet scheduling was done in the RNC)

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 62

HSDPA amp Enhance Uplink

bull Gain in Performance

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 63

HSDPA

bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to

individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes

bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)

12 64

HSDPA

bull New frame structurendash Five subframesW-CDMA

framendash User data can be

assigned on a subframe basis

ndash System can adjust in 2ms

ndash Each subframe is a transmission time interval (TTI) = 2ms

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 65

HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared

resource is also in the time domain

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 66

HSDPA

bull Another view

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

Spreading Code

12 67

HSDPAbull Link Adaptation

ndash Remember the fast power control is commonly used to

bull Maintain constant EnergyNoise ratiobull Reduce effect of fading

ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant

EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 68

HSDPA

ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)

ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum

bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user

bull 1 ndash 2 Mbs closer to achievable under real conditions

12 69

HSDPA

bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE

bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms

bull CQI (0-30) each mapping into a modulation SF etc

bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression

bull

12 70

HSDPA

bull Schedulingndash The scheduler decides which user

should get access to each TTI ndash CQI provides input into a Scheduler

bull Proportional Fair (PF) Scheduler can be uses

bull Implementation Specific

12 71

HSDPA

bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number

of spreading codes limits rate not power so likely receive first transmission

ndash At greater distances move from BS see more errors IR will require additional transmission but not many

ndash HARQ only retransmit upon an ACK or NACK

12 72

HSDPA

From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007

12 73

HSDPA

bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2

ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent

Scheduling

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 39

RRC Layerbull The RRC layer offers the core network the following

servicesndash General control service which is used as an information

broadcast servicendash Notification service which is used for paging and

notification of a selected UEsndash Dedicated control service which is used for

establishmentrelease of a connection and transfer of messages using the connection

bull The RRC layer comprises the following functionsndash Broadcasting information from network to all UEsndash Radio resource handling (eg code allocation handover

admission control and measurement reportingcontrol)ndash QoS Controlndash UE measurement reporting and control of the reportingndash Power Control Encryption and Integrity protection

12 40

RLC Layer

bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is

appended to the information unit received from the higher layer

ndash Assured and un assured data transferbull The RLC layer comprises the following functions

ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the

WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the

control plane)ndash Duplicate detectionndash Flow controlndash Ciphering

12 41

RLC Layer-Modesbull Transparent-TM

ndash No header attachedndash SARndash SDU discard

bull Delete SDU if not sent before timer expiresndash Used for

bull Voicebull Some signaling

bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability

bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat

12 42

RLC Layer

From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the

UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

12 43

UE-Call states

bull Designed to ndash Take advantage of bursty nature of

datandash Save batter powerndash Maintains logical session and tracks

mobility but when appropriatendash releases dedicated resources to

increase overall capacityndash asleeps the UE

12 44

UE-Call states

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 45

UE-Call states

bull Idle modendash No active sessionndash UE monitors

Paging CHndash Sleeps between

paging cycles

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 46

UE-Call states

bull CELL_DCH state (Dedicated)ndash A dedicated physical

channel is allocated to the UE in uplink and downlink

ndash The UE is known on cell level according to its current active set

ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE

ndash Call typesbull Circuit Switched always in

this statebull Packet Switched in this

state if transferring large volume of data

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 47

UE-Call states

bull CELL_FACH state(Forward Access Ch)

ndash No dedicated physical channel is allocated to the UE

ndash The UE continuously monitors a FACH in the downlink

ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel

ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update

ndash Radio not put to sleepndash For packet switched sessions

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 48

UE-Call states

bull CELL_PCH state (Paging Ch)ndash No dedicated physical

channel is allocated to the UE

ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash Sleep between pagesndash A logical session is still upndash The position of the UE is

known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 49

UE-Call states

bull URA_PCH State ndash No dedicated channel is

allocated to the UEndash The UE selects a PCH with

the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state

ndash Similar to CELL_PCH state only the at the URA level

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 50

Power Control-PC

bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to

ensure that there is enough power for mobiles at the cell edge

bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control

commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command

ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break

12 51

Power Control

bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss

by means of a downlink beacon signalndash Provide a coarse initial power setting of

the mobile at the beginning of a connection

ndash Apply only prior to initiating the transmission on RACH or CPCH

12 52

Packet Access in WCDMA

bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection

bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared

bull RNC can decide when and how to send packets based on type of packet traffic

ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech

ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video

ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing

ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail

bull RNC can assign a packet to a specific channel

Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 53

Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the

downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft

handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts

bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts

bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink

orthogonal code is reserved according to maximum bit rate

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 54

Packet Access in WCDMA

bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner

bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer

bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate

bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and

bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 55

Packet Access in WCDMA

bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased

bull Advantagesndash resources are in full usage due to longer transmission

timendash small variation in interference levelndash longer uplink range due to lower bit rate

bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 56

Packet Access in WCDMA

bull Time division is normally used with shared channels and code division is normally used with dedicated channels

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 57

Packet Access in WCDMA

bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users

could be based on required transmission powerbull Users close to the BS requires less

transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate

bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput

bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 58

HSDPA amp Enhance Uplink

bull HSDPA = High Speed Downlink Packet Access

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 59

HSDPA amp Enhance Uplink

bull Remember it is better (more efficient) to have a large number of users sharing a single server

bull This lead to a desire to have fast allocation of shared resources

bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code

bull Uplink resourcesndash Interference at the BS

bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)

bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)

12 60

HSDPA amp Enhance Uplink

bull UTRAN Architecture with HSDPA and enhanced uplink

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 61

HSDPA amp Enhance Uplink

bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK

modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and

coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function

moved to Node-B (WCDMA packet scheduling was done in the RNC)

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 62

HSDPA amp Enhance Uplink

bull Gain in Performance

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 63

HSDPA

bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to

individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes

bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)

12 64

HSDPA

bull New frame structurendash Five subframesW-CDMA

framendash User data can be

assigned on a subframe basis

ndash System can adjust in 2ms

ndash Each subframe is a transmission time interval (TTI) = 2ms

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 65

HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared

resource is also in the time domain

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 66

HSDPA

bull Another view

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

Spreading Code

12 67

HSDPAbull Link Adaptation

ndash Remember the fast power control is commonly used to

bull Maintain constant EnergyNoise ratiobull Reduce effect of fading

ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant

EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 68

HSDPA

ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)

ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum

bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user

bull 1 ndash 2 Mbs closer to achievable under real conditions

12 69

HSDPA

bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE

bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms

bull CQI (0-30) each mapping into a modulation SF etc

bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression

bull

12 70

HSDPA

bull Schedulingndash The scheduler decides which user

should get access to each TTI ndash CQI provides input into a Scheduler

bull Proportional Fair (PF) Scheduler can be uses

bull Implementation Specific

12 71

HSDPA

bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number

of spreading codes limits rate not power so likely receive first transmission

ndash At greater distances move from BS see more errors IR will require additional transmission but not many

ndash HARQ only retransmit upon an ACK or NACK

12 72

HSDPA

From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007

12 73

HSDPA

bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2

ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent

Scheduling

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 40

RLC Layer

bull The RLC layer offers the following services to the higher layersndash Layer 2 connection establishmentreleasendash Transparent data transfer ie no protocol overhead is

appended to the information unit received from the higher layer

ndash Assured and un assured data transferbull The RLC layer comprises the following functions

ndash Segmentation and assemblyndash Transfer of user datandash Error correction by means of retransmission optimized for the

WCDMA physical layerndash Sequence integrity-In sequence delivery (used by at least the

control plane)ndash Duplicate detectionndash Flow controlndash Ciphering

12 41

RLC Layer-Modesbull Transparent-TM

ndash No header attachedndash SARndash SDU discard

bull Delete SDU if not sent before timer expiresndash Used for

bull Voicebull Some signaling

bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability

bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat

12 42

RLC Layer

From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the

UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

12 43

UE-Call states

bull Designed to ndash Take advantage of bursty nature of

datandash Save batter powerndash Maintains logical session and tracks

mobility but when appropriatendash releases dedicated resources to

increase overall capacityndash asleeps the UE

12 44

UE-Call states

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 45

UE-Call states

bull Idle modendash No active sessionndash UE monitors

Paging CHndash Sleeps between

paging cycles

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 46

UE-Call states

bull CELL_DCH state (Dedicated)ndash A dedicated physical

channel is allocated to the UE in uplink and downlink

ndash The UE is known on cell level according to its current active set

ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE

ndash Call typesbull Circuit Switched always in

this statebull Packet Switched in this

state if transferring large volume of data

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 47

UE-Call states

bull CELL_FACH state(Forward Access Ch)

ndash No dedicated physical channel is allocated to the UE

ndash The UE continuously monitors a FACH in the downlink

ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel

ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update

ndash Radio not put to sleepndash For packet switched sessions

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 48

UE-Call states

bull CELL_PCH state (Paging Ch)ndash No dedicated physical

channel is allocated to the UE

ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash Sleep between pagesndash A logical session is still upndash The position of the UE is

known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 49

UE-Call states

bull URA_PCH State ndash No dedicated channel is

allocated to the UEndash The UE selects a PCH with

the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state

ndash Similar to CELL_PCH state only the at the URA level

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 50

Power Control-PC

bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to

ensure that there is enough power for mobiles at the cell edge

bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control

commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command

ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break

12 51

Power Control

bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss

by means of a downlink beacon signalndash Provide a coarse initial power setting of

the mobile at the beginning of a connection

ndash Apply only prior to initiating the transmission on RACH or CPCH

12 52

Packet Access in WCDMA

bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection

bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared

bull RNC can decide when and how to send packets based on type of packet traffic

ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech

ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video

ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing

ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail

bull RNC can assign a packet to a specific channel

Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 53

Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the

downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft

handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts

bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts

bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink

orthogonal code is reserved according to maximum bit rate

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 54

Packet Access in WCDMA

bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner

bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer

bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate

bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and

bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 55

Packet Access in WCDMA

bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased

bull Advantagesndash resources are in full usage due to longer transmission

timendash small variation in interference levelndash longer uplink range due to lower bit rate

bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 56

Packet Access in WCDMA

bull Time division is normally used with shared channels and code division is normally used with dedicated channels

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 57

Packet Access in WCDMA

bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users

could be based on required transmission powerbull Users close to the BS requires less

transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate

bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput

bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 58

HSDPA amp Enhance Uplink

bull HSDPA = High Speed Downlink Packet Access

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 59

HSDPA amp Enhance Uplink

bull Remember it is better (more efficient) to have a large number of users sharing a single server

bull This lead to a desire to have fast allocation of shared resources

bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code

bull Uplink resourcesndash Interference at the BS

bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)

bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)

12 60

HSDPA amp Enhance Uplink

bull UTRAN Architecture with HSDPA and enhanced uplink

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 61

HSDPA amp Enhance Uplink

bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK

modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and

coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function

moved to Node-B (WCDMA packet scheduling was done in the RNC)

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 62

HSDPA amp Enhance Uplink

bull Gain in Performance

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 63

HSDPA

bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to

individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes

bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)

12 64

HSDPA

bull New frame structurendash Five subframesW-CDMA

framendash User data can be

assigned on a subframe basis

ndash System can adjust in 2ms

ndash Each subframe is a transmission time interval (TTI) = 2ms

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 65

HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared

resource is also in the time domain

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 66

HSDPA

bull Another view

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

Spreading Code

12 67

HSDPAbull Link Adaptation

ndash Remember the fast power control is commonly used to

bull Maintain constant EnergyNoise ratiobull Reduce effect of fading

ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant

EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 68

HSDPA

ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)

ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum

bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user

bull 1 ndash 2 Mbs closer to achievable under real conditions

12 69

HSDPA

bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE

bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms

bull CQI (0-30) each mapping into a modulation SF etc

bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression

bull

12 70

HSDPA

bull Schedulingndash The scheduler decides which user

should get access to each TTI ndash CQI provides input into a Scheduler

bull Proportional Fair (PF) Scheduler can be uses

bull Implementation Specific

12 71

HSDPA

bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number

of spreading codes limits rate not power so likely receive first transmission

ndash At greater distances move from BS see more errors IR will require additional transmission but not many

ndash HARQ only retransmit upon an ACK or NACK

12 72

HSDPA

From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007

12 73

HSDPA

bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2

ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent

Scheduling

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 41

RLC Layer-Modesbull Transparent-TM

ndash No header attachedndash SARndash SDU discard

bull Delete SDU if not sent before timer expiresndash Used for

bull Voicebull Some signaling

bull Unacknowledged (UM)ndash Header with Seq numberndash SARndash Padndash SDU discardndash Provides some reliability

bull Acknowledged Mode (AM)ndash Siding window-ARQndash Selective repeat

12 42

RLC Layer

From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the

UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

12 43

UE-Call states

bull Designed to ndash Take advantage of bursty nature of

datandash Save batter powerndash Maintains logical session and tracks

mobility but when appropriatendash releases dedicated resources to

increase overall capacityndash asleeps the UE

12 44

UE-Call states

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 45

UE-Call states

bull Idle modendash No active sessionndash UE monitors

Paging CHndash Sleeps between

paging cycles

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 46

UE-Call states

bull CELL_DCH state (Dedicated)ndash A dedicated physical

channel is allocated to the UE in uplink and downlink

ndash The UE is known on cell level according to its current active set

ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE

ndash Call typesbull Circuit Switched always in

this statebull Packet Switched in this

state if transferring large volume of data

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 47

UE-Call states

bull CELL_FACH state(Forward Access Ch)

ndash No dedicated physical channel is allocated to the UE

ndash The UE continuously monitors a FACH in the downlink

ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel

ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update

ndash Radio not put to sleepndash For packet switched sessions

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 48

UE-Call states

bull CELL_PCH state (Paging Ch)ndash No dedicated physical

channel is allocated to the UE

ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash Sleep between pagesndash A logical session is still upndash The position of the UE is

known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 49

UE-Call states

bull URA_PCH State ndash No dedicated channel is

allocated to the UEndash The UE selects a PCH with

the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state

ndash Similar to CELL_PCH state only the at the URA level

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 50

Power Control-PC

bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to

ensure that there is enough power for mobiles at the cell edge

bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control

commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command

ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break

12 51

Power Control

bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss

by means of a downlink beacon signalndash Provide a coarse initial power setting of

the mobile at the beginning of a connection

ndash Apply only prior to initiating the transmission on RACH or CPCH

12 52

Packet Access in WCDMA

bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection

bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared

bull RNC can decide when and how to send packets based on type of packet traffic

ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech

ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video

ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing

ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail

bull RNC can assign a packet to a specific channel

Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 53

Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the

downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft

handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts

bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts

bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink

orthogonal code is reserved according to maximum bit rate

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 54

Packet Access in WCDMA

bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner

bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer

bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate

bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and

bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 55

Packet Access in WCDMA

bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased

bull Advantagesndash resources are in full usage due to longer transmission

timendash small variation in interference levelndash longer uplink range due to lower bit rate

bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 56

Packet Access in WCDMA

bull Time division is normally used with shared channels and code division is normally used with dedicated channels

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 57

Packet Access in WCDMA

bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users

could be based on required transmission powerbull Users close to the BS requires less

transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate

bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput

bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 58

HSDPA amp Enhance Uplink

bull HSDPA = High Speed Downlink Packet Access

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 59

HSDPA amp Enhance Uplink

bull Remember it is better (more efficient) to have a large number of users sharing a single server

bull This lead to a desire to have fast allocation of shared resources

bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code

bull Uplink resourcesndash Interference at the BS

bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)

bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)

12 60

HSDPA amp Enhance Uplink

bull UTRAN Architecture with HSDPA and enhanced uplink

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 61

HSDPA amp Enhance Uplink

bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK

modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and

coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function

moved to Node-B (WCDMA packet scheduling was done in the RNC)

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 62

HSDPA amp Enhance Uplink

bull Gain in Performance

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 63

HSDPA

bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to

individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes

bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)

12 64

HSDPA

bull New frame structurendash Five subframesW-CDMA

framendash User data can be

assigned on a subframe basis

ndash System can adjust in 2ms

ndash Each subframe is a transmission time interval (TTI) = 2ms

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 65

HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared

resource is also in the time domain

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 66

HSDPA

bull Another view

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

Spreading Code

12 67

HSDPAbull Link Adaptation

ndash Remember the fast power control is commonly used to

bull Maintain constant EnergyNoise ratiobull Reduce effect of fading

ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant

EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 68

HSDPA

ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)

ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum

bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user

bull 1 ndash 2 Mbs closer to achievable under real conditions

12 69

HSDPA

bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE

bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms

bull CQI (0-30) each mapping into a modulation SF etc

bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression

bull

12 70

HSDPA

bull Schedulingndash The scheduler decides which user

should get access to each TTI ndash CQI provides input into a Scheduler

bull Proportional Fair (PF) Scheduler can be uses

bull Implementation Specific

12 71

HSDPA

bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number

of spreading codes limits rate not power so likely receive first transmission

ndash At greater distances move from BS see more errors IR will require additional transmission but not many

ndash HARQ only retransmit upon an ACK or NACK

12 72

HSDPA

From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007

12 73

HSDPA

bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2

ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent

Scheduling

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 42

RLC Layer

From Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-HaroldquoOptimizing TCP and RLC Interaction in the

UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

12 43

UE-Call states

bull Designed to ndash Take advantage of bursty nature of

datandash Save batter powerndash Maintains logical session and tracks

mobility but when appropriatendash releases dedicated resources to

increase overall capacityndash asleeps the UE

12 44

UE-Call states

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 45

UE-Call states

bull Idle modendash No active sessionndash UE monitors

Paging CHndash Sleeps between

paging cycles

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 46

UE-Call states

bull CELL_DCH state (Dedicated)ndash A dedicated physical

channel is allocated to the UE in uplink and downlink

ndash The UE is known on cell level according to its current active set

ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE

ndash Call typesbull Circuit Switched always in

this statebull Packet Switched in this

state if transferring large volume of data

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 47

UE-Call states

bull CELL_FACH state(Forward Access Ch)

ndash No dedicated physical channel is allocated to the UE

ndash The UE continuously monitors a FACH in the downlink

ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel

ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update

ndash Radio not put to sleepndash For packet switched sessions

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 48

UE-Call states

bull CELL_PCH state (Paging Ch)ndash No dedicated physical

channel is allocated to the UE

ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash Sleep between pagesndash A logical session is still upndash The position of the UE is

known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 49

UE-Call states

bull URA_PCH State ndash No dedicated channel is

allocated to the UEndash The UE selects a PCH with

the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state

ndash Similar to CELL_PCH state only the at the URA level

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 50

Power Control-PC

bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to

ensure that there is enough power for mobiles at the cell edge

bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control

commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command

ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break

12 51

Power Control

bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss

by means of a downlink beacon signalndash Provide a coarse initial power setting of

the mobile at the beginning of a connection

ndash Apply only prior to initiating the transmission on RACH or CPCH

12 52

Packet Access in WCDMA

bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection

bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared

bull RNC can decide when and how to send packets based on type of packet traffic

ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech

ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video

ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing

ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail

bull RNC can assign a packet to a specific channel

Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 53

Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the

downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft

handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts

bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts

bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink

orthogonal code is reserved according to maximum bit rate

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 54

Packet Access in WCDMA

bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner

bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer

bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate

bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and

bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 55

Packet Access in WCDMA

bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased

bull Advantagesndash resources are in full usage due to longer transmission

timendash small variation in interference levelndash longer uplink range due to lower bit rate

bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 56

Packet Access in WCDMA

bull Time division is normally used with shared channels and code division is normally used with dedicated channels

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 57

Packet Access in WCDMA

bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users

could be based on required transmission powerbull Users close to the BS requires less

transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate

bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput

bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 58

HSDPA amp Enhance Uplink

bull HSDPA = High Speed Downlink Packet Access

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 59

HSDPA amp Enhance Uplink

bull Remember it is better (more efficient) to have a large number of users sharing a single server

bull This lead to a desire to have fast allocation of shared resources

bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code

bull Uplink resourcesndash Interference at the BS

bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)

bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)

12 60

HSDPA amp Enhance Uplink

bull UTRAN Architecture with HSDPA and enhanced uplink

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 61

HSDPA amp Enhance Uplink

bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK

modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and

coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function

moved to Node-B (WCDMA packet scheduling was done in the RNC)

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 62

HSDPA amp Enhance Uplink

bull Gain in Performance

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 63

HSDPA

bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to

individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes

bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)

12 64

HSDPA

bull New frame structurendash Five subframesW-CDMA

framendash User data can be

assigned on a subframe basis

ndash System can adjust in 2ms

ndash Each subframe is a transmission time interval (TTI) = 2ms

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 65

HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared

resource is also in the time domain

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 66

HSDPA

bull Another view

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

Spreading Code

12 67

HSDPAbull Link Adaptation

ndash Remember the fast power control is commonly used to

bull Maintain constant EnergyNoise ratiobull Reduce effect of fading

ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant

EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 68

HSDPA

ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)

ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum

bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user

bull 1 ndash 2 Mbs closer to achievable under real conditions

12 69

HSDPA

bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE

bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms

bull CQI (0-30) each mapping into a modulation SF etc

bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression

bull

12 70

HSDPA

bull Schedulingndash The scheduler decides which user

should get access to each TTI ndash CQI provides input into a Scheduler

bull Proportional Fair (PF) Scheduler can be uses

bull Implementation Specific

12 71

HSDPA

bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number

of spreading codes limits rate not power so likely receive first transmission

ndash At greater distances move from BS see more errors IR will require additional transmission but not many

ndash HARQ only retransmit upon an ACK or NACK

12 72

HSDPA

From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007

12 73

HSDPA

bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2

ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent

Scheduling

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 43

UE-Call states

bull Designed to ndash Take advantage of bursty nature of

datandash Save batter powerndash Maintains logical session and tracks

mobility but when appropriatendash releases dedicated resources to

increase overall capacityndash asleeps the UE

12 44

UE-Call states

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 45

UE-Call states

bull Idle modendash No active sessionndash UE monitors

Paging CHndash Sleeps between

paging cycles

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 46

UE-Call states

bull CELL_DCH state (Dedicated)ndash A dedicated physical

channel is allocated to the UE in uplink and downlink

ndash The UE is known on cell level according to its current active set

ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE

ndash Call typesbull Circuit Switched always in

this statebull Packet Switched in this

state if transferring large volume of data

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 47

UE-Call states

bull CELL_FACH state(Forward Access Ch)

ndash No dedicated physical channel is allocated to the UE

ndash The UE continuously monitors a FACH in the downlink

ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel

ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update

ndash Radio not put to sleepndash For packet switched sessions

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 48

UE-Call states

bull CELL_PCH state (Paging Ch)ndash No dedicated physical

channel is allocated to the UE

ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash Sleep between pagesndash A logical session is still upndash The position of the UE is

known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 49

UE-Call states

bull URA_PCH State ndash No dedicated channel is

allocated to the UEndash The UE selects a PCH with

the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state

ndash Similar to CELL_PCH state only the at the URA level

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 50

Power Control-PC

bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to

ensure that there is enough power for mobiles at the cell edge

bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control

commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command

ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break

12 51

Power Control

bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss

by means of a downlink beacon signalndash Provide a coarse initial power setting of

the mobile at the beginning of a connection

ndash Apply only prior to initiating the transmission on RACH or CPCH

12 52

Packet Access in WCDMA

bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection

bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared

bull RNC can decide when and how to send packets based on type of packet traffic

ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech

ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video

ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing

ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail

bull RNC can assign a packet to a specific channel

Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 53

Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the

downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft

handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts

bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts

bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink

orthogonal code is reserved according to maximum bit rate

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 54

Packet Access in WCDMA

bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner

bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer

bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate

bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and

bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 55

Packet Access in WCDMA

bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased

bull Advantagesndash resources are in full usage due to longer transmission

timendash small variation in interference levelndash longer uplink range due to lower bit rate

bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 56

Packet Access in WCDMA

bull Time division is normally used with shared channels and code division is normally used with dedicated channels

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 57

Packet Access in WCDMA

bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users

could be based on required transmission powerbull Users close to the BS requires less

transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate

bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput

bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 58

HSDPA amp Enhance Uplink

bull HSDPA = High Speed Downlink Packet Access

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 59

HSDPA amp Enhance Uplink

bull Remember it is better (more efficient) to have a large number of users sharing a single server

bull This lead to a desire to have fast allocation of shared resources

bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code

bull Uplink resourcesndash Interference at the BS

bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)

bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)

12 60

HSDPA amp Enhance Uplink

bull UTRAN Architecture with HSDPA and enhanced uplink

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 61

HSDPA amp Enhance Uplink

bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK

modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and

coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function

moved to Node-B (WCDMA packet scheduling was done in the RNC)

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 62

HSDPA amp Enhance Uplink

bull Gain in Performance

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 63

HSDPA

bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to

individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes

bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)

12 64

HSDPA

bull New frame structurendash Five subframesW-CDMA

framendash User data can be

assigned on a subframe basis

ndash System can adjust in 2ms

ndash Each subframe is a transmission time interval (TTI) = 2ms

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 65

HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared

resource is also in the time domain

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 66

HSDPA

bull Another view

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

Spreading Code

12 67

HSDPAbull Link Adaptation

ndash Remember the fast power control is commonly used to

bull Maintain constant EnergyNoise ratiobull Reduce effect of fading

ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant

EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 68

HSDPA

ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)

ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum

bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user

bull 1 ndash 2 Mbs closer to achievable under real conditions

12 69

HSDPA

bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE

bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms

bull CQI (0-30) each mapping into a modulation SF etc

bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression

bull

12 70

HSDPA

bull Schedulingndash The scheduler decides which user

should get access to each TTI ndash CQI provides input into a Scheduler

bull Proportional Fair (PF) Scheduler can be uses

bull Implementation Specific

12 71

HSDPA

bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number

of spreading codes limits rate not power so likely receive first transmission

ndash At greater distances move from BS see more errors IR will require additional transmission but not many

ndash HARQ only retransmit upon an ACK or NACK

12 72

HSDPA

From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007

12 73

HSDPA

bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2

ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent

Scheduling

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 44

UE-Call states

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 45

UE-Call states

bull Idle modendash No active sessionndash UE monitors

Paging CHndash Sleeps between

paging cycles

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 46

UE-Call states

bull CELL_DCH state (Dedicated)ndash A dedicated physical

channel is allocated to the UE in uplink and downlink

ndash The UE is known on cell level according to its current active set

ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE

ndash Call typesbull Circuit Switched always in

this statebull Packet Switched in this

state if transferring large volume of data

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 47

UE-Call states

bull CELL_FACH state(Forward Access Ch)

ndash No dedicated physical channel is allocated to the UE

ndash The UE continuously monitors a FACH in the downlink

ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel

ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update

ndash Radio not put to sleepndash For packet switched sessions

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 48

UE-Call states

bull CELL_PCH state (Paging Ch)ndash No dedicated physical

channel is allocated to the UE

ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash Sleep between pagesndash A logical session is still upndash The position of the UE is

known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 49

UE-Call states

bull URA_PCH State ndash No dedicated channel is

allocated to the UEndash The UE selects a PCH with

the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state

ndash Similar to CELL_PCH state only the at the URA level

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 50

Power Control-PC

bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to

ensure that there is enough power for mobiles at the cell edge

bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control

commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command

ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break

12 51

Power Control

bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss

by means of a downlink beacon signalndash Provide a coarse initial power setting of

the mobile at the beginning of a connection

ndash Apply only prior to initiating the transmission on RACH or CPCH

12 52

Packet Access in WCDMA

bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection

bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared

bull RNC can decide when and how to send packets based on type of packet traffic

ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech

ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video

ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing

ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail

bull RNC can assign a packet to a specific channel

Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 53

Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the

downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft

handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts

bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts

bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink

orthogonal code is reserved according to maximum bit rate

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 54

Packet Access in WCDMA

bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner

bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer

bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate

bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and

bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 55

Packet Access in WCDMA

bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased

bull Advantagesndash resources are in full usage due to longer transmission

timendash small variation in interference levelndash longer uplink range due to lower bit rate

bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 56

Packet Access in WCDMA

bull Time division is normally used with shared channels and code division is normally used with dedicated channels

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 57

Packet Access in WCDMA

bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users

could be based on required transmission powerbull Users close to the BS requires less

transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate

bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput

bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 58

HSDPA amp Enhance Uplink

bull HSDPA = High Speed Downlink Packet Access

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 59

HSDPA amp Enhance Uplink

bull Remember it is better (more efficient) to have a large number of users sharing a single server

bull This lead to a desire to have fast allocation of shared resources

bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code

bull Uplink resourcesndash Interference at the BS

bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)

bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)

12 60

HSDPA amp Enhance Uplink

bull UTRAN Architecture with HSDPA and enhanced uplink

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 61

HSDPA amp Enhance Uplink

bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK

modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and

coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function

moved to Node-B (WCDMA packet scheduling was done in the RNC)

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 62

HSDPA amp Enhance Uplink

bull Gain in Performance

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 63

HSDPA

bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to

individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes

bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)

12 64

HSDPA

bull New frame structurendash Five subframesW-CDMA

framendash User data can be

assigned on a subframe basis

ndash System can adjust in 2ms

ndash Each subframe is a transmission time interval (TTI) = 2ms

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 65

HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared

resource is also in the time domain

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 66

HSDPA

bull Another view

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

Spreading Code

12 67

HSDPAbull Link Adaptation

ndash Remember the fast power control is commonly used to

bull Maintain constant EnergyNoise ratiobull Reduce effect of fading

ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant

EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 68

HSDPA

ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)

ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum

bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user

bull 1 ndash 2 Mbs closer to achievable under real conditions

12 69

HSDPA

bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE

bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms

bull CQI (0-30) each mapping into a modulation SF etc

bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression

bull

12 70

HSDPA

bull Schedulingndash The scheduler decides which user

should get access to each TTI ndash CQI provides input into a Scheduler

bull Proportional Fair (PF) Scheduler can be uses

bull Implementation Specific

12 71

HSDPA

bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number

of spreading codes limits rate not power so likely receive first transmission

ndash At greater distances move from BS see more errors IR will require additional transmission but not many

ndash HARQ only retransmit upon an ACK or NACK

12 72

HSDPA

From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007

12 73

HSDPA

bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2

ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent

Scheduling

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 45

UE-Call states

bull Idle modendash No active sessionndash UE monitors

Paging CHndash Sleeps between

paging cycles

From httpwwwumtsworldcomtechnologyRCC_stateshtm

12 46

UE-Call states

bull CELL_DCH state (Dedicated)ndash A dedicated physical

channel is allocated to the UE in uplink and downlink

ndash The UE is known on cell level according to its current active set

ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE

ndash Call typesbull Circuit Switched always in

this statebull Packet Switched in this

state if transferring large volume of data

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 47

UE-Call states

bull CELL_FACH state(Forward Access Ch)

ndash No dedicated physical channel is allocated to the UE

ndash The UE continuously monitors a FACH in the downlink

ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel

ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update

ndash Radio not put to sleepndash For packet switched sessions

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 48

UE-Call states

bull CELL_PCH state (Paging Ch)ndash No dedicated physical

channel is allocated to the UE

ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash Sleep between pagesndash A logical session is still upndash The position of the UE is

known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 49

UE-Call states

bull URA_PCH State ndash No dedicated channel is

allocated to the UEndash The UE selects a PCH with

the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state

ndash Similar to CELL_PCH state only the at the URA level

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 50

Power Control-PC

bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to

ensure that there is enough power for mobiles at the cell edge

bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control

commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command

ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break

12 51

Power Control

bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss

by means of a downlink beacon signalndash Provide a coarse initial power setting of

the mobile at the beginning of a connection

ndash Apply only prior to initiating the transmission on RACH or CPCH

12 52

Packet Access in WCDMA

bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection

bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared

bull RNC can decide when and how to send packets based on type of packet traffic

ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech

ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video

ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing

ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail

bull RNC can assign a packet to a specific channel

Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 53

Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the

downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft

handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts

bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts

bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink

orthogonal code is reserved according to maximum bit rate

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 54

Packet Access in WCDMA

bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner

bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer

bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate

bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and

bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 55

Packet Access in WCDMA

bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased

bull Advantagesndash resources are in full usage due to longer transmission

timendash small variation in interference levelndash longer uplink range due to lower bit rate

bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 56

Packet Access in WCDMA

bull Time division is normally used with shared channels and code division is normally used with dedicated channels

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 57

Packet Access in WCDMA

bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users

could be based on required transmission powerbull Users close to the BS requires less

transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate

bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput

bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 58

HSDPA amp Enhance Uplink

bull HSDPA = High Speed Downlink Packet Access

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 59

HSDPA amp Enhance Uplink

bull Remember it is better (more efficient) to have a large number of users sharing a single server

bull This lead to a desire to have fast allocation of shared resources

bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code

bull Uplink resourcesndash Interference at the BS

bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)

bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)

12 60

HSDPA amp Enhance Uplink

bull UTRAN Architecture with HSDPA and enhanced uplink

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 61

HSDPA amp Enhance Uplink

bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK

modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and

coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function

moved to Node-B (WCDMA packet scheduling was done in the RNC)

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 62

HSDPA amp Enhance Uplink

bull Gain in Performance

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 63

HSDPA

bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to

individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes

bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)

12 64

HSDPA

bull New frame structurendash Five subframesW-CDMA

framendash User data can be

assigned on a subframe basis

ndash System can adjust in 2ms

ndash Each subframe is a transmission time interval (TTI) = 2ms

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 65

HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared

resource is also in the time domain

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 66

HSDPA

bull Another view

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

Spreading Code

12 67

HSDPAbull Link Adaptation

ndash Remember the fast power control is commonly used to

bull Maintain constant EnergyNoise ratiobull Reduce effect of fading

ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant

EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 68

HSDPA

ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)

ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum

bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user

bull 1 ndash 2 Mbs closer to achievable under real conditions

12 69

HSDPA

bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE

bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms

bull CQI (0-30) each mapping into a modulation SF etc

bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression

bull

12 70

HSDPA

bull Schedulingndash The scheduler decides which user

should get access to each TTI ndash CQI provides input into a Scheduler

bull Proportional Fair (PF) Scheduler can be uses

bull Implementation Specific

12 71

HSDPA

bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number

of spreading codes limits rate not power so likely receive first transmission

ndash At greater distances move from BS see more errors IR will require additional transmission but not many

ndash HARQ only retransmit upon an ACK or NACK

12 72

HSDPA

From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007

12 73

HSDPA

bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2

ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent

Scheduling

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 46

UE-Call states

bull CELL_DCH state (Dedicated)ndash A dedicated physical

channel is allocated to the UE in uplink and downlink

ndash The UE is known on cell level according to its current active set

ndash Dedicated transport channels downlink and uplink (TDD) shared transport channels and a combination of these transport channels can be used by the UE

ndash Call typesbull Circuit Switched always in

this statebull Packet Switched in this

state if transferring large volume of data

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 47

UE-Call states

bull CELL_FACH state(Forward Access Ch)

ndash No dedicated physical channel is allocated to the UE

ndash The UE continuously monitors a FACH in the downlink

ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel

ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update

ndash Radio not put to sleepndash For packet switched sessions

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 48

UE-Call states

bull CELL_PCH state (Paging Ch)ndash No dedicated physical

channel is allocated to the UE

ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash Sleep between pagesndash A logical session is still upndash The position of the UE is

known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 49

UE-Call states

bull URA_PCH State ndash No dedicated channel is

allocated to the UEndash The UE selects a PCH with

the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state

ndash Similar to CELL_PCH state only the at the URA level

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 50

Power Control-PC

bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to

ensure that there is enough power for mobiles at the cell edge

bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control

commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command

ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break

12 51

Power Control

bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss

by means of a downlink beacon signalndash Provide a coarse initial power setting of

the mobile at the beginning of a connection

ndash Apply only prior to initiating the transmission on RACH or CPCH

12 52

Packet Access in WCDMA

bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection

bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared

bull RNC can decide when and how to send packets based on type of packet traffic

ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech

ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video

ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing

ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail

bull RNC can assign a packet to a specific channel

Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 53

Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the

downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft

handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts

bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts

bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink

orthogonal code is reserved according to maximum bit rate

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 54

Packet Access in WCDMA

bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner

bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer

bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate

bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and

bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 55

Packet Access in WCDMA

bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased

bull Advantagesndash resources are in full usage due to longer transmission

timendash small variation in interference levelndash longer uplink range due to lower bit rate

bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 56

Packet Access in WCDMA

bull Time division is normally used with shared channels and code division is normally used with dedicated channels

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 57

Packet Access in WCDMA

bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users

could be based on required transmission powerbull Users close to the BS requires less

transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate

bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput

bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 58

HSDPA amp Enhance Uplink

bull HSDPA = High Speed Downlink Packet Access

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 59

HSDPA amp Enhance Uplink

bull Remember it is better (more efficient) to have a large number of users sharing a single server

bull This lead to a desire to have fast allocation of shared resources

bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code

bull Uplink resourcesndash Interference at the BS

bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)

bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)

12 60

HSDPA amp Enhance Uplink

bull UTRAN Architecture with HSDPA and enhanced uplink

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 61

HSDPA amp Enhance Uplink

bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK

modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and

coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function

moved to Node-B (WCDMA packet scheduling was done in the RNC)

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 62

HSDPA amp Enhance Uplink

bull Gain in Performance

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 63

HSDPA

bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to

individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes

bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)

12 64

HSDPA

bull New frame structurendash Five subframesW-CDMA

framendash User data can be

assigned on a subframe basis

ndash System can adjust in 2ms

ndash Each subframe is a transmission time interval (TTI) = 2ms

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 65

HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared

resource is also in the time domain

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 66

HSDPA

bull Another view

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

Spreading Code

12 67

HSDPAbull Link Adaptation

ndash Remember the fast power control is commonly used to

bull Maintain constant EnergyNoise ratiobull Reduce effect of fading

ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant

EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 68

HSDPA

ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)

ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum

bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user

bull 1 ndash 2 Mbs closer to achievable under real conditions

12 69

HSDPA

bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE

bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms

bull CQI (0-30) each mapping into a modulation SF etc

bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression

bull

12 70

HSDPA

bull Schedulingndash The scheduler decides which user

should get access to each TTI ndash CQI provides input into a Scheduler

bull Proportional Fair (PF) Scheduler can be uses

bull Implementation Specific

12 71

HSDPA

bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number

of spreading codes limits rate not power so likely receive first transmission

ndash At greater distances move from BS see more errors IR will require additional transmission but not many

ndash HARQ only retransmit upon an ACK or NACK

12 72

HSDPA

From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007

12 73

HSDPA

bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2

ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent

Scheduling

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 47

UE-Call states

bull CELL_FACH state(Forward Access Ch)

ndash No dedicated physical channel is allocated to the UE

ndash The UE continuously monitors a FACH in the downlink

ndash The UE is assigned a default common or shared transport channel in the uplink (eg RACH) that it can use anytime according to the access procedure for that transport channel

ndash The position of the UE is known by UTRAN on cell level according to the cell where the UE last made a cell update

ndash Radio not put to sleepndash For packet switched sessions

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 48

UE-Call states

bull CELL_PCH state (Paging Ch)ndash No dedicated physical

channel is allocated to the UE

ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash Sleep between pagesndash A logical session is still upndash The position of the UE is

known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 49

UE-Call states

bull URA_PCH State ndash No dedicated channel is

allocated to the UEndash The UE selects a PCH with

the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state

ndash Similar to CELL_PCH state only the at the URA level

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 50

Power Control-PC

bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to

ensure that there is enough power for mobiles at the cell edge

bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control

commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command

ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break

12 51

Power Control

bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss

by means of a downlink beacon signalndash Provide a coarse initial power setting of

the mobile at the beginning of a connection

ndash Apply only prior to initiating the transmission on RACH or CPCH

12 52

Packet Access in WCDMA

bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection

bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared

bull RNC can decide when and how to send packets based on type of packet traffic

ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech

ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video

ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing

ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail

bull RNC can assign a packet to a specific channel

Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 53

Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the

downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft

handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts

bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts

bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink

orthogonal code is reserved according to maximum bit rate

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 54

Packet Access in WCDMA

bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner

bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer

bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate

bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and

bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 55

Packet Access in WCDMA

bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased

bull Advantagesndash resources are in full usage due to longer transmission

timendash small variation in interference levelndash longer uplink range due to lower bit rate

bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 56

Packet Access in WCDMA

bull Time division is normally used with shared channels and code division is normally used with dedicated channels

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 57

Packet Access in WCDMA

bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users

could be based on required transmission powerbull Users close to the BS requires less

transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate

bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput

bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 58

HSDPA amp Enhance Uplink

bull HSDPA = High Speed Downlink Packet Access

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 59

HSDPA amp Enhance Uplink

bull Remember it is better (more efficient) to have a large number of users sharing a single server

bull This lead to a desire to have fast allocation of shared resources

bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code

bull Uplink resourcesndash Interference at the BS

bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)

bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)

12 60

HSDPA amp Enhance Uplink

bull UTRAN Architecture with HSDPA and enhanced uplink

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 61

HSDPA amp Enhance Uplink

bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK

modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and

coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function

moved to Node-B (WCDMA packet scheduling was done in the RNC)

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 62

HSDPA amp Enhance Uplink

bull Gain in Performance

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 63

HSDPA

bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to

individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes

bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)

12 64

HSDPA

bull New frame structurendash Five subframesW-CDMA

framendash User data can be

assigned on a subframe basis

ndash System can adjust in 2ms

ndash Each subframe is a transmission time interval (TTI) = 2ms

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 65

HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared

resource is also in the time domain

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 66

HSDPA

bull Another view

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

Spreading Code

12 67

HSDPAbull Link Adaptation

ndash Remember the fast power control is commonly used to

bull Maintain constant EnergyNoise ratiobull Reduce effect of fading

ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant

EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 68

HSDPA

ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)

ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum

bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user

bull 1 ndash 2 Mbs closer to achievable under real conditions

12 69

HSDPA

bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE

bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms

bull CQI (0-30) each mapping into a modulation SF etc

bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression

bull

12 70

HSDPA

bull Schedulingndash The scheduler decides which user

should get access to each TTI ndash CQI provides input into a Scheduler

bull Proportional Fair (PF) Scheduler can be uses

bull Implementation Specific

12 71

HSDPA

bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number

of spreading codes limits rate not power so likely receive first transmission

ndash At greater distances move from BS see more errors IR will require additional transmission but not many

ndash HARQ only retransmit upon an ACK or NACK

12 72

HSDPA

From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007

12 73

HSDPA

bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2

ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent

Scheduling

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 48

UE-Call states

bull CELL_PCH state (Paging Ch)ndash No dedicated physical

channel is allocated to the UE

ndash The UE selects a PCH with the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash Sleep between pagesndash A logical session is still upndash The position of the UE is

known by UTRAN on cell level according to the cell where the UE last made a cell update in CELL_FACH state

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 49

UE-Call states

bull URA_PCH State ndash No dedicated channel is

allocated to the UEndash The UE selects a PCH with

the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state

ndash Similar to CELL_PCH state only the at the URA level

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 50

Power Control-PC

bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to

ensure that there is enough power for mobiles at the cell edge

bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control

commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command

ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break

12 51

Power Control

bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss

by means of a downlink beacon signalndash Provide a coarse initial power setting of

the mobile at the beginning of a connection

ndash Apply only prior to initiating the transmission on RACH or CPCH

12 52

Packet Access in WCDMA

bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection

bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared

bull RNC can decide when and how to send packets based on type of packet traffic

ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech

ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video

ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing

ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail

bull RNC can assign a packet to a specific channel

Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 53

Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the

downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft

handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts

bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts

bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink

orthogonal code is reserved according to maximum bit rate

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 54

Packet Access in WCDMA

bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner

bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer

bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate

bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and

bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 55

Packet Access in WCDMA

bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased

bull Advantagesndash resources are in full usage due to longer transmission

timendash small variation in interference levelndash longer uplink range due to lower bit rate

bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 56

Packet Access in WCDMA

bull Time division is normally used with shared channels and code division is normally used with dedicated channels

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 57

Packet Access in WCDMA

bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users

could be based on required transmission powerbull Users close to the BS requires less

transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate

bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput

bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 58

HSDPA amp Enhance Uplink

bull HSDPA = High Speed Downlink Packet Access

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 59

HSDPA amp Enhance Uplink

bull Remember it is better (more efficient) to have a large number of users sharing a single server

bull This lead to a desire to have fast allocation of shared resources

bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code

bull Uplink resourcesndash Interference at the BS

bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)

bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)

12 60

HSDPA amp Enhance Uplink

bull UTRAN Architecture with HSDPA and enhanced uplink

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 61

HSDPA amp Enhance Uplink

bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK

modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and

coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function

moved to Node-B (WCDMA packet scheduling was done in the RNC)

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 62

HSDPA amp Enhance Uplink

bull Gain in Performance

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 63

HSDPA

bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to

individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes

bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)

12 64

HSDPA

bull New frame structurendash Five subframesW-CDMA

framendash User data can be

assigned on a subframe basis

ndash System can adjust in 2ms

ndash Each subframe is a transmission time interval (TTI) = 2ms

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 65

HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared

resource is also in the time domain

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 66

HSDPA

bull Another view

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

Spreading Code

12 67

HSDPAbull Link Adaptation

ndash Remember the fast power control is commonly used to

bull Maintain constant EnergyNoise ratiobull Reduce effect of fading

ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant

EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 68

HSDPA

ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)

ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum

bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user

bull 1 ndash 2 Mbs closer to achievable under real conditions

12 69

HSDPA

bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE

bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms

bull CQI (0-30) each mapping into a modulation SF etc

bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression

bull

12 70

HSDPA

bull Schedulingndash The scheduler decides which user

should get access to each TTI ndash CQI provides input into a Scheduler

bull Proportional Fair (PF) Scheduler can be uses

bull Implementation Specific

12 71

HSDPA

bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number

of spreading codes limits rate not power so likely receive first transmission

ndash At greater distances move from BS see more errors IR will require additional transmission but not many

ndash HARQ only retransmit upon an ACK or NACK

12 72

HSDPA

From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007

12 73

HSDPA

bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2

ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent

Scheduling

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 49

UE-Call states

bull URA_PCH State ndash No dedicated channel is

allocated to the UEndash The UE selects a PCH with

the algorithm and uses DRX for monitoring the selected PCH via an associated PICH

ndash No uplink activity is possible

ndash The location of the UE is known on UTRAN Registration area level according to the URA assigned to the UE during the last URA update in CELL_FACH state

ndash Similar to CELL_PCH state only the at the URA level

Modified rom httpwwwumtsworldcomtechnologyRCC_stateshtm

12 50

Power Control-PC

bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to

ensure that there is enough power for mobiles at the cell edge

bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control

commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command

ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break

12 51

Power Control

bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss

by means of a downlink beacon signalndash Provide a coarse initial power setting of

the mobile at the beginning of a connection

ndash Apply only prior to initiating the transmission on RACH or CPCH

12 52

Packet Access in WCDMA

bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection

bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared

bull RNC can decide when and how to send packets based on type of packet traffic

ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech

ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video

ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing

ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail

bull RNC can assign a packet to a specific channel

Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 53

Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the

downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft

handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts

bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts

bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink

orthogonal code is reserved according to maximum bit rate

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 54

Packet Access in WCDMA

bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner

bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer

bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate

bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and

bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 55

Packet Access in WCDMA

bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased

bull Advantagesndash resources are in full usage due to longer transmission

timendash small variation in interference levelndash longer uplink range due to lower bit rate

bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 56

Packet Access in WCDMA

bull Time division is normally used with shared channels and code division is normally used with dedicated channels

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 57

Packet Access in WCDMA

bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users

could be based on required transmission powerbull Users close to the BS requires less

transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate

bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput

bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 58

HSDPA amp Enhance Uplink

bull HSDPA = High Speed Downlink Packet Access

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 59

HSDPA amp Enhance Uplink

bull Remember it is better (more efficient) to have a large number of users sharing a single server

bull This lead to a desire to have fast allocation of shared resources

bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code

bull Uplink resourcesndash Interference at the BS

bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)

bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)

12 60

HSDPA amp Enhance Uplink

bull UTRAN Architecture with HSDPA and enhanced uplink

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 61

HSDPA amp Enhance Uplink

bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK

modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and

coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function

moved to Node-B (WCDMA packet scheduling was done in the RNC)

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 62

HSDPA amp Enhance Uplink

bull Gain in Performance

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 63

HSDPA

bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to

individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes

bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)

12 64

HSDPA

bull New frame structurendash Five subframesW-CDMA

framendash User data can be

assigned on a subframe basis

ndash System can adjust in 2ms

ndash Each subframe is a transmission time interval (TTI) = 2ms

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 65

HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared

resource is also in the time domain

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 66

HSDPA

bull Another view

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

Spreading Code

12 67

HSDPAbull Link Adaptation

ndash Remember the fast power control is commonly used to

bull Maintain constant EnergyNoise ratiobull Reduce effect of fading

ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant

EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 68

HSDPA

ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)

ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum

bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user

bull 1 ndash 2 Mbs closer to achievable under real conditions

12 69

HSDPA

bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE

bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms

bull CQI (0-30) each mapping into a modulation SF etc

bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression

bull

12 70

HSDPA

bull Schedulingndash The scheduler decides which user

should get access to each TTI ndash CQI provides input into a Scheduler

bull Proportional Fair (PF) Scheduler can be uses

bull Implementation Specific

12 71

HSDPA

bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number

of spreading codes limits rate not power so likely receive first transmission

ndash At greater distances move from BS see more errors IR will require additional transmission but not many

ndash HARQ only retransmit upon an ACK or NACK

12 72

HSDPA

From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007

12 73

HSDPA

bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2

ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent

Scheduling

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 50

Power Control-PC

bull Fast Closed Loop PC ndash Inner Loop PCndash Feedback informationndash Uplink PC is used for near-far problem Downlink PC is to

ensure that there is enough power for mobiles at the cell edge

bull Two special cases for fast closed loop PCndash Soft handover- how to react to multiple power control

commands from several sources At the mobile a ldquopower downrdquo command has higher priority over ldquopower uprdquo command

ndash Compressed mode- Large step size is used after a compressed frame to allow the power level to converge more quickly to the correct value after the break

12 51

Power Control

bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss

by means of a downlink beacon signalndash Provide a coarse initial power setting of

the mobile at the beginning of a connection

ndash Apply only prior to initiating the transmission on RACH or CPCH

12 52

Packet Access in WCDMA

bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection

bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared

bull RNC can decide when and how to send packets based on type of packet traffic

ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech

ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video

ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing

ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail

bull RNC can assign a packet to a specific channel

Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 53

Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the

downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft

handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts

bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts

bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink

orthogonal code is reserved according to maximum bit rate

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 54

Packet Access in WCDMA

bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner

bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer

bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate

bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and

bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 55

Packet Access in WCDMA

bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased

bull Advantagesndash resources are in full usage due to longer transmission

timendash small variation in interference levelndash longer uplink range due to lower bit rate

bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 56

Packet Access in WCDMA

bull Time division is normally used with shared channels and code division is normally used with dedicated channels

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 57

Packet Access in WCDMA

bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users

could be based on required transmission powerbull Users close to the BS requires less

transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate

bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput

bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 58

HSDPA amp Enhance Uplink

bull HSDPA = High Speed Downlink Packet Access

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 59

HSDPA amp Enhance Uplink

bull Remember it is better (more efficient) to have a large number of users sharing a single server

bull This lead to a desire to have fast allocation of shared resources

bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code

bull Uplink resourcesndash Interference at the BS

bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)

bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)

12 60

HSDPA amp Enhance Uplink

bull UTRAN Architecture with HSDPA and enhanced uplink

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 61

HSDPA amp Enhance Uplink

bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK

modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and

coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function

moved to Node-B (WCDMA packet scheduling was done in the RNC)

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 62

HSDPA amp Enhance Uplink

bull Gain in Performance

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 63

HSDPA

bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to

individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes

bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)

12 64

HSDPA

bull New frame structurendash Five subframesW-CDMA

framendash User data can be

assigned on a subframe basis

ndash System can adjust in 2ms

ndash Each subframe is a transmission time interval (TTI) = 2ms

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 65

HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared

resource is also in the time domain

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 66

HSDPA

bull Another view

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

Spreading Code

12 67

HSDPAbull Link Adaptation

ndash Remember the fast power control is commonly used to

bull Maintain constant EnergyNoise ratiobull Reduce effect of fading

ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant

EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 68

HSDPA

ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)

ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum

bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user

bull 1 ndash 2 Mbs closer to achievable under real conditions

12 69

HSDPA

bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE

bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms

bull CQI (0-30) each mapping into a modulation SF etc

bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression

bull

12 70

HSDPA

bull Schedulingndash The scheduler decides which user

should get access to each TTI ndash CQI provides input into a Scheduler

bull Proportional Fair (PF) Scheduler can be uses

bull Implementation Specific

12 71

HSDPA

bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number

of spreading codes limits rate not power so likely receive first transmission

ndash At greater distances move from BS see more errors IR will require additional transmission but not many

ndash HARQ only retransmit upon an ACK or NACK

12 72

HSDPA

From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007

12 73

HSDPA

bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2

ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent

Scheduling

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 51

Power Control

bull Open loop PCndash No feedback informationndash Make a rough estimate of the path loss

by means of a downlink beacon signalndash Provide a coarse initial power setting of

the mobile at the beginning of a connection

ndash Apply only prior to initiating the transmission on RACH or CPCH

12 52

Packet Access in WCDMA

bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection

bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared

bull RNC can decide when and how to send packets based on type of packet traffic

ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech

ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video

ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing

ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail

bull RNC can assign a packet to a specific channel

Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 53

Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the

downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft

handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts

bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts

bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink

orthogonal code is reserved according to maximum bit rate

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 54

Packet Access in WCDMA

bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner

bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer

bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate

bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and

bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 55

Packet Access in WCDMA

bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased

bull Advantagesndash resources are in full usage due to longer transmission

timendash small variation in interference levelndash longer uplink range due to lower bit rate

bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 56

Packet Access in WCDMA

bull Time division is normally used with shared channels and code division is normally used with dedicated channels

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 57

Packet Access in WCDMA

bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users

could be based on required transmission powerbull Users close to the BS requires less

transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate

bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput

bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 58

HSDPA amp Enhance Uplink

bull HSDPA = High Speed Downlink Packet Access

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 59

HSDPA amp Enhance Uplink

bull Remember it is better (more efficient) to have a large number of users sharing a single server

bull This lead to a desire to have fast allocation of shared resources

bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code

bull Uplink resourcesndash Interference at the BS

bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)

bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)

12 60

HSDPA amp Enhance Uplink

bull UTRAN Architecture with HSDPA and enhanced uplink

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 61

HSDPA amp Enhance Uplink

bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK

modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and

coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function

moved to Node-B (WCDMA packet scheduling was done in the RNC)

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 62

HSDPA amp Enhance Uplink

bull Gain in Performance

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 63

HSDPA

bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to

individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes

bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)

12 64

HSDPA

bull New frame structurendash Five subframesW-CDMA

framendash User data can be

assigned on a subframe basis

ndash System can adjust in 2ms

ndash Each subframe is a transmission time interval (TTI) = 2ms

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 65

HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared

resource is also in the time domain

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 66

HSDPA

bull Another view

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

Spreading Code

12 67

HSDPAbull Link Adaptation

ndash Remember the fast power control is commonly used to

bull Maintain constant EnergyNoise ratiobull Reduce effect of fading

ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant

EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 68

HSDPA

ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)

ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum

bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user

bull 1 ndash 2 Mbs closer to achievable under real conditions

12 69

HSDPA

bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE

bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms

bull CQI (0-30) each mapping into a modulation SF etc

bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression

bull

12 70

HSDPA

bull Schedulingndash The scheduler decides which user

should get access to each TTI ndash CQI provides input into a Scheduler

bull Proportional Fair (PF) Scheduler can be uses

bull Implementation Specific

12 71

HSDPA

bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number

of spreading codes limits rate not power so likely receive first transmission

ndash At greater distances move from BS see more errors IR will require additional transmission but not many

ndash HARQ only retransmit upon an ACK or NACK

12 72

HSDPA

From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007

12 73

HSDPA

bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2

ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent

Scheduling

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 52

Packet Access in WCDMA

bull Packet allocations performed in the RNC by the packet scheduler (PS)ndash Time code or powerndash Bit ratesndash Holding timesndash Channel selection

bull PS allocates traffic to specific channelsndash Commonndash Delectatedndash Shared

bull RNC can decide when and how to send packets based on type of packet traffic

ndash Conversational class -gt real-time connection performed between human users really low delay nearly symmetric eg speech

ndash Streaming class -gt real-time connection transferring data as a steady and continuous low delay asymmetric eg video

ndash Interactive class -gt non-real-time packet data response requested from other end-user reasonable round-trip delay eg Web browsing

ndash Background class -gt non-real-time packet data no immediate action expected less sensitive to delivery time eg e-mail

bull RNC can assign a packet to a specific channel

Modified from P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 53

Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the

downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft

handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts

bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts

bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink

orthogonal code is reserved according to maximum bit rate

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 54

Packet Access in WCDMA

bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner

bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer

bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate

bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and

bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 55

Packet Access in WCDMA

bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased

bull Advantagesndash resources are in full usage due to longer transmission

timendash small variation in interference levelndash longer uplink range due to lower bit rate

bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 56

Packet Access in WCDMA

bull Time division is normally used with shared channels and code division is normally used with dedicated channels

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 57

Packet Access in WCDMA

bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users

could be based on required transmission powerbull Users close to the BS requires less

transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate

bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput

bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 58

HSDPA amp Enhance Uplink

bull HSDPA = High Speed Downlink Packet Access

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 59

HSDPA amp Enhance Uplink

bull Remember it is better (more efficient) to have a large number of users sharing a single server

bull This lead to a desire to have fast allocation of shared resources

bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code

bull Uplink resourcesndash Interference at the BS

bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)

bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)

12 60

HSDPA amp Enhance Uplink

bull UTRAN Architecture with HSDPA and enhanced uplink

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 61

HSDPA amp Enhance Uplink

bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK

modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and

coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function

moved to Node-B (WCDMA packet scheduling was done in the RNC)

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 62

HSDPA amp Enhance Uplink

bull Gain in Performance

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 63

HSDPA

bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to

individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes

bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)

12 64

HSDPA

bull New frame structurendash Five subframesW-CDMA

framendash User data can be

assigned on a subframe basis

ndash System can adjust in 2ms

ndash Each subframe is a transmission time interval (TTI) = 2ms

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 65

HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared

resource is also in the time domain

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 66

HSDPA

bull Another view

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

Spreading Code

12 67

HSDPAbull Link Adaptation

ndash Remember the fast power control is commonly used to

bull Maintain constant EnergyNoise ratiobull Reduce effect of fading

ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant

EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 68

HSDPA

ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)

ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum

bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user

bull 1 ndash 2 Mbs closer to achievable under real conditions

12 69

HSDPA

bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE

bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms

bull CQI (0-30) each mapping into a modulation SF etc

bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression

bull

12 70

HSDPA

bull Schedulingndash The scheduler decides which user

should get access to each TTI ndash CQI provides input into a Scheduler

bull Proportional Fair (PF) Scheduler can be uses

bull Implementation Specific

12 71

HSDPA

bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number

of spreading codes limits rate not power so likely receive first transmission

ndash At greater distances move from BS see more errors IR will require additional transmission but not many

ndash HARQ only retransmit upon an ACK or NACK

12 72

HSDPA

From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007

12 73

HSDPA

bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2

ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent

Scheduling

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 53

Packet Access in WCDMAbull Common channels - RACH in the uplink and FACH in the

downlinkndash One or few RACH or FACH per sectorndash Low setup timendash No feedback channel -gt no fast closed loop power control no soft

handover use fixed powerndash Poor link-level radio performance and generated more interferencendash Suitable for small data amounts

bull Common channels - CPCH in the uplinkndash Bit rate can be highndash Support fast power controlndash Suitable for small or medium data amounts

bull Dedicated Channel - DCH in the uplink and downlinkndash Use fast power control and soft handoverndash Better link-level radio performance and less interferencendash Longer setup timendash Up to 2 Mbpsndash Suitable for large data amountsndash Not suitable for bursty datandash In case of changing bit rate in the downlink the downlink

orthogonal code is reserved according to maximum bit rate

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 54

Packet Access in WCDMA

bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner

bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer

bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate

bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and

bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 55

Packet Access in WCDMA

bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased

bull Advantagesndash resources are in full usage due to longer transmission

timendash small variation in interference levelndash longer uplink range due to lower bit rate

bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 56

Packet Access in WCDMA

bull Time division is normally used with shared channels and code division is normally used with dedicated channels

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 57

Packet Access in WCDMA

bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users

could be based on required transmission powerbull Users close to the BS requires less

transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate

bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput

bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 58

HSDPA amp Enhance Uplink

bull HSDPA = High Speed Downlink Packet Access

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 59

HSDPA amp Enhance Uplink

bull Remember it is better (more efficient) to have a large number of users sharing a single server

bull This lead to a desire to have fast allocation of shared resources

bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code

bull Uplink resourcesndash Interference at the BS

bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)

bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)

12 60

HSDPA amp Enhance Uplink

bull UTRAN Architecture with HSDPA and enhanced uplink

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 61

HSDPA amp Enhance Uplink

bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK

modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and

coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function

moved to Node-B (WCDMA packet scheduling was done in the RNC)

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 62

HSDPA amp Enhance Uplink

bull Gain in Performance

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 63

HSDPA

bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to

individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes

bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)

12 64

HSDPA

bull New frame structurendash Five subframesW-CDMA

framendash User data can be

assigned on a subframe basis

ndash System can adjust in 2ms

ndash Each subframe is a transmission time interval (TTI) = 2ms

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 65

HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared

resource is also in the time domain

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 66

HSDPA

bull Another view

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

Spreading Code

12 67

HSDPAbull Link Adaptation

ndash Remember the fast power control is commonly used to

bull Maintain constant EnergyNoise ratiobull Reduce effect of fading

ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant

EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 68

HSDPA

ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)

ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum

bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user

bull 1 ndash 2 Mbs closer to achievable under real conditions

12 69

HSDPA

bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE

bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms

bull CQI (0-30) each mapping into a modulation SF etc

bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression

bull

12 70

HSDPA

bull Schedulingndash The scheduler decides which user

should get access to each TTI ndash CQI provides input into a Scheduler

bull Proportional Fair (PF) Scheduler can be uses

bull Implementation Specific

12 71

HSDPA

bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number

of spreading codes limits rate not power so likely receive first transmission

ndash At greater distances move from BS see more errors IR will require additional transmission but not many

ndash HARQ only retransmit upon an ACK or NACK

12 72

HSDPA

From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007

12 73

HSDPA

bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2

ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent

Scheduling

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 54

Packet Access in WCDMA

bull In WCDMA packet scheduling algorithms can be done in two ways in a time or code division manner

bull Time division scheduling ndash one user is allocated a channel at a time (10 ms frame)ndash all available capacity can be allocated to that userndash high data rate for a short period of timendash increase more users each user has to wait longer

bull Advantages of time division scheduling ndash high bit rate required less energy per bitndash less interferencendash shorter delay due to high bit rate

bull Disadvantagesndash high unused physical resources due to short transmission time andndash relatively long set up and release timendash high variations in the interference levels due to high bit rate and

bursty trafficndash limited uplink range of high bit rate due to mobilersquos limitedndash transmission power

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 55

Packet Access in WCDMA

bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased

bull Advantagesndash resources are in full usage due to longer transmission

timendash small variation in interference levelndash longer uplink range due to lower bit rate

bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 56

Packet Access in WCDMA

bull Time division is normally used with shared channels and code division is normally used with dedicated channels

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 57

Packet Access in WCDMA

bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users

could be based on required transmission powerbull Users close to the BS requires less

transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate

bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput

bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 58

HSDPA amp Enhance Uplink

bull HSDPA = High Speed Downlink Packet Access

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 59

HSDPA amp Enhance Uplink

bull Remember it is better (more efficient) to have a large number of users sharing a single server

bull This lead to a desire to have fast allocation of shared resources

bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code

bull Uplink resourcesndash Interference at the BS

bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)

bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)

12 60

HSDPA amp Enhance Uplink

bull UTRAN Architecture with HSDPA and enhanced uplink

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 61

HSDPA amp Enhance Uplink

bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK

modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and

coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function

moved to Node-B (WCDMA packet scheduling was done in the RNC)

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 62

HSDPA amp Enhance Uplink

bull Gain in Performance

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 63

HSDPA

bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to

individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes

bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)

12 64

HSDPA

bull New frame structurendash Five subframesW-CDMA

framendash User data can be

assigned on a subframe basis

ndash System can adjust in 2ms

ndash Each subframe is a transmission time interval (TTI) = 2ms

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 65

HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared

resource is also in the time domain

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 66

HSDPA

bull Another view

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

Spreading Code

12 67

HSDPAbull Link Adaptation

ndash Remember the fast power control is commonly used to

bull Maintain constant EnergyNoise ratiobull Reduce effect of fading

ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant

EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 68

HSDPA

ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)

ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum

bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user

bull 1 ndash 2 Mbs closer to achievable under real conditions

12 69

HSDPA

bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE

bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms

bull CQI (0-30) each mapping into a modulation SF etc

bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression

bull

12 70

HSDPA

bull Schedulingndash The scheduler decides which user

should get access to each TTI ndash CQI provides input into a Scheduler

bull Proportional Fair (PF) Scheduler can be uses

bull Implementation Specific

12 71

HSDPA

bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number

of spreading codes limits rate not power so likely receive first transmission

ndash At greater distances move from BS see more errors IR will require additional transmission but not many

ndash HARQ only retransmit upon an ACK or NACK

12 72

HSDPA

From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007

12 73

HSDPA

bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2

ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent

Scheduling

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 55

Packet Access in WCDMA

bull Code division schedulingndash many users are allocated the channels simultaneouslyndash the capacity is shared with all usersndash low data rate for a long period of timendash increase more users each userrsquos bit rate is decreased

bull Advantagesndash resources are in full usage due to longer transmission

timendash small variation in interference levelndash longer uplink range due to lower bit rate

bull Disadvantagesndash longer transmission delay due to low bit ratendash high interference due to high energy per bitndash low total throughput

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 56

Packet Access in WCDMA

bull Time division is normally used with shared channels and code division is normally used with dedicated channels

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 57

Packet Access in WCDMA

bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users

could be based on required transmission powerbull Users close to the BS requires less

transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate

bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput

bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 58

HSDPA amp Enhance Uplink

bull HSDPA = High Speed Downlink Packet Access

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 59

HSDPA amp Enhance Uplink

bull Remember it is better (more efficient) to have a large number of users sharing a single server

bull This lead to a desire to have fast allocation of shared resources

bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code

bull Uplink resourcesndash Interference at the BS

bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)

bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)

12 60

HSDPA amp Enhance Uplink

bull UTRAN Architecture with HSDPA and enhanced uplink

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 61

HSDPA amp Enhance Uplink

bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK

modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and

coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function

moved to Node-B (WCDMA packet scheduling was done in the RNC)

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 62

HSDPA amp Enhance Uplink

bull Gain in Performance

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 63

HSDPA

bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to

individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes

bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)

12 64

HSDPA

bull New frame structurendash Five subframesW-CDMA

framendash User data can be

assigned on a subframe basis

ndash System can adjust in 2ms

ndash Each subframe is a transmission time interval (TTI) = 2ms

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 65

HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared

resource is also in the time domain

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 66

HSDPA

bull Another view

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

Spreading Code

12 67

HSDPAbull Link Adaptation

ndash Remember the fast power control is commonly used to

bull Maintain constant EnergyNoise ratiobull Reduce effect of fading

ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant

EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 68

HSDPA

ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)

ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum

bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user

bull 1 ndash 2 Mbs closer to achievable under real conditions

12 69

HSDPA

bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE

bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms

bull CQI (0-30) each mapping into a modulation SF etc

bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression

bull

12 70

HSDPA

bull Schedulingndash The scheduler decides which user

should get access to each TTI ndash CQI provides input into a Scheduler

bull Proportional Fair (PF) Scheduler can be uses

bull Implementation Specific

12 71

HSDPA

bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number

of spreading codes limits rate not power so likely receive first transmission

ndash At greater distances move from BS see more errors IR will require additional transmission but not many

ndash HARQ only retransmit upon an ACK or NACK

12 72

HSDPA

From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007

12 73

HSDPA

bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2

ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent

Scheduling

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 56

Packet Access in WCDMA

bull Time division is normally used with shared channels and code division is normally used with dedicated channels

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 57

Packet Access in WCDMA

bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users

could be based on required transmission powerbull Users close to the BS requires less

transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate

bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput

bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 58

HSDPA amp Enhance Uplink

bull HSDPA = High Speed Downlink Packet Access

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 59

HSDPA amp Enhance Uplink

bull Remember it is better (more efficient) to have a large number of users sharing a single server

bull This lead to a desire to have fast allocation of shared resources

bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code

bull Uplink resourcesndash Interference at the BS

bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)

bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)

12 60

HSDPA amp Enhance Uplink

bull UTRAN Architecture with HSDPA and enhanced uplink

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 61

HSDPA amp Enhance Uplink

bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK

modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and

coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function

moved to Node-B (WCDMA packet scheduling was done in the RNC)

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 62

HSDPA amp Enhance Uplink

bull Gain in Performance

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 63

HSDPA

bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to

individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes

bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)

12 64

HSDPA

bull New frame structurendash Five subframesW-CDMA

framendash User data can be

assigned on a subframe basis

ndash System can adjust in 2ms

ndash Each subframe is a transmission time interval (TTI) = 2ms

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 65

HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared

resource is also in the time domain

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 66

HSDPA

bull Another view

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

Spreading Code

12 67

HSDPAbull Link Adaptation

ndash Remember the fast power control is commonly used to

bull Maintain constant EnergyNoise ratiobull Reduce effect of fading

ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant

EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 68

HSDPA

ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)

ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum

bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user

bull 1 ndash 2 Mbs closer to achievable under real conditions

12 69

HSDPA

bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE

bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms

bull CQI (0-30) each mapping into a modulation SF etc

bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression

bull

12 70

HSDPA

bull Schedulingndash The scheduler decides which user

should get access to each TTI ndash CQI provides input into a Scheduler

bull Proportional Fair (PF) Scheduler can be uses

bull Implementation Specific

12 71

HSDPA

bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number

of spreading codes limits rate not power so likely receive first transmission

ndash At greater distances move from BS see more errors IR will require additional transmission but not many

ndash HARQ only retransmit upon an ACK or NACK

12 72

HSDPA

From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007

12 73

HSDPA

bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2

ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent

Scheduling

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 57

Packet Access in WCDMA

bull Transmission Power-based Schedulingndash The bit rate allocated to each packet data users

could be based on required transmission powerbull Users close to the BS requires less

transmission power and can get a higher bit rate whereas users at the cell edge could get lower bit rate

bull Advantagesndash minimize the average power sent per bitndash less interferencendash increase the throughput

bull bull Disadvantagesndash accurate power estimationndash unfair resource allocation

From P Chong wwwcomlabhutfiopetus238lecture9_PacketAccesspdf

12 58

HSDPA amp Enhance Uplink

bull HSDPA = High Speed Downlink Packet Access

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 59

HSDPA amp Enhance Uplink

bull Remember it is better (more efficient) to have a large number of users sharing a single server

bull This lead to a desire to have fast allocation of shared resources

bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code

bull Uplink resourcesndash Interference at the BS

bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)

bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)

12 60

HSDPA amp Enhance Uplink

bull UTRAN Architecture with HSDPA and enhanced uplink

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 61

HSDPA amp Enhance Uplink

bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK

modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and

coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function

moved to Node-B (WCDMA packet scheduling was done in the RNC)

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 62

HSDPA amp Enhance Uplink

bull Gain in Performance

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 63

HSDPA

bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to

individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes

bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)

12 64

HSDPA

bull New frame structurendash Five subframesW-CDMA

framendash User data can be

assigned on a subframe basis

ndash System can adjust in 2ms

ndash Each subframe is a transmission time interval (TTI) = 2ms

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 65

HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared

resource is also in the time domain

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 66

HSDPA

bull Another view

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

Spreading Code

12 67

HSDPAbull Link Adaptation

ndash Remember the fast power control is commonly used to

bull Maintain constant EnergyNoise ratiobull Reduce effect of fading

ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant

EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 68

HSDPA

ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)

ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum

bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user

bull 1 ndash 2 Mbs closer to achievable under real conditions

12 69

HSDPA

bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE

bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms

bull CQI (0-30) each mapping into a modulation SF etc

bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression

bull

12 70

HSDPA

bull Schedulingndash The scheduler decides which user

should get access to each TTI ndash CQI provides input into a Scheduler

bull Proportional Fair (PF) Scheduler can be uses

bull Implementation Specific

12 71

HSDPA

bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number

of spreading codes limits rate not power so likely receive first transmission

ndash At greater distances move from BS see more errors IR will require additional transmission but not many

ndash HARQ only retransmit upon an ACK or NACK

12 72

HSDPA

From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007

12 73

HSDPA

bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2

ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent

Scheduling

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 58

HSDPA amp Enhance Uplink

bull HSDPA = High Speed Downlink Packet Access

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 59

HSDPA amp Enhance Uplink

bull Remember it is better (more efficient) to have a large number of users sharing a single server

bull This lead to a desire to have fast allocation of shared resources

bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code

bull Uplink resourcesndash Interference at the BS

bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)

bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)

12 60

HSDPA amp Enhance Uplink

bull UTRAN Architecture with HSDPA and enhanced uplink

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 61

HSDPA amp Enhance Uplink

bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK

modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and

coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function

moved to Node-B (WCDMA packet scheduling was done in the RNC)

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 62

HSDPA amp Enhance Uplink

bull Gain in Performance

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 63

HSDPA

bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to

individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes

bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)

12 64

HSDPA

bull New frame structurendash Five subframesW-CDMA

framendash User data can be

assigned on a subframe basis

ndash System can adjust in 2ms

ndash Each subframe is a transmission time interval (TTI) = 2ms

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 65

HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared

resource is also in the time domain

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 66

HSDPA

bull Another view

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

Spreading Code

12 67

HSDPAbull Link Adaptation

ndash Remember the fast power control is commonly used to

bull Maintain constant EnergyNoise ratiobull Reduce effect of fading

ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant

EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 68

HSDPA

ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)

ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum

bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user

bull 1 ndash 2 Mbs closer to achievable under real conditions

12 69

HSDPA

bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE

bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms

bull CQI (0-30) each mapping into a modulation SF etc

bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression

bull

12 70

HSDPA

bull Schedulingndash The scheduler decides which user

should get access to each TTI ndash CQI provides input into a Scheduler

bull Proportional Fair (PF) Scheduler can be uses

bull Implementation Specific

12 71

HSDPA

bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number

of spreading codes limits rate not power so likely receive first transmission

ndash At greater distances move from BS see more errors IR will require additional transmission but not many

ndash HARQ only retransmit upon an ACK or NACK

12 72

HSDPA

From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007

12 73

HSDPA

bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2

ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent

Scheduling

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 59

HSDPA amp Enhance Uplink

bull Remember it is better (more efficient) to have a large number of users sharing a single server

bull This lead to a desire to have fast allocation of shared resources

bull Downlink resourcesndash Transmit power (interference to other cells)ndash Channelization code

bull Uplink resourcesndash Interference at the BS

bull Other fast mechanismsndash Fast schedulingndash Fast ARQ (hybrid ARQ) (this is in addition to the RLC AM)

bull To be fast mechanisms must be close to the air interfacendash Mechanisms in BS (Node B)

12 60

HSDPA amp Enhance Uplink

bull UTRAN Architecture with HSDPA and enhanced uplink

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 61

HSDPA amp Enhance Uplink

bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK

modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and

coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function

moved to Node-B (WCDMA packet scheduling was done in the RNC)

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 62

HSDPA amp Enhance Uplink

bull Gain in Performance

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 63

HSDPA

bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to

individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes

bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)

12 64

HSDPA

bull New frame structurendash Five subframesW-CDMA

framendash User data can be

assigned on a subframe basis

ndash System can adjust in 2ms

ndash Each subframe is a transmission time interval (TTI) = 2ms

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 65

HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared

resource is also in the time domain

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 66

HSDPA

bull Another view

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

Spreading Code

12 67

HSDPAbull Link Adaptation

ndash Remember the fast power control is commonly used to

bull Maintain constant EnergyNoise ratiobull Reduce effect of fading

ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant

EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 68

HSDPA

ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)

ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum

bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user

bull 1 ndash 2 Mbs closer to achievable under real conditions

12 69

HSDPA

bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE

bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms

bull CQI (0-30) each mapping into a modulation SF etc

bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression

bull

12 70

HSDPA

bull Schedulingndash The scheduler decides which user

should get access to each TTI ndash CQI provides input into a Scheduler

bull Proportional Fair (PF) Scheduler can be uses

bull Implementation Specific

12 71

HSDPA

bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number

of spreading codes limits rate not power so likely receive first transmission

ndash At greater distances move from BS see more errors IR will require additional transmission but not many

ndash HARQ only retransmit upon an ACK or NACK

12 72

HSDPA

From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007

12 73

HSDPA

bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2

ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent

Scheduling

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 60

HSDPA amp Enhance Uplink

bull UTRAN Architecture with HSDPA and enhanced uplink

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 61

HSDPA amp Enhance Uplink

bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK

modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and

coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function

moved to Node-B (WCDMA packet scheduling was done in the RNC)

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 62

HSDPA amp Enhance Uplink

bull Gain in Performance

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 63

HSDPA

bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to

individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes

bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)

12 64

HSDPA

bull New frame structurendash Five subframesW-CDMA

framendash User data can be

assigned on a subframe basis

ndash System can adjust in 2ms

ndash Each subframe is a transmission time interval (TTI) = 2ms

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 65

HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared

resource is also in the time domain

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 66

HSDPA

bull Another view

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

Spreading Code

12 67

HSDPAbull Link Adaptation

ndash Remember the fast power control is commonly used to

bull Maintain constant EnergyNoise ratiobull Reduce effect of fading

ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant

EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 68

HSDPA

ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)

ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum

bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user

bull 1 ndash 2 Mbs closer to achievable under real conditions

12 69

HSDPA

bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE

bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms

bull CQI (0-30) each mapping into a modulation SF etc

bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression

bull

12 70

HSDPA

bull Schedulingndash The scheduler decides which user

should get access to each TTI ndash CQI provides input into a Scheduler

bull Proportional Fair (PF) Scheduler can be uses

bull Implementation Specific

12 71

HSDPA

bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number

of spreading codes limits rate not power so likely receive first transmission

ndash At greater distances move from BS see more errors IR will require additional transmission but not many

ndash HARQ only retransmit upon an ACK or NACK

12 72

HSDPA

From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007

12 73

HSDPA

bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2

ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent

Scheduling

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 61

HSDPA amp Enhance Uplink

bull Changesndash shorter radio framendash new high-speed downlink channelsndash use of 16 QAM modulation in addition to QPSK

modulationndash code multiplexing combined with time multiplexingndash a new uplink control channelndash fast link adaptation using adaptive modulation and

coding (AMC)ndash use of hybrid automatic-repeat-request (HARQ)ndash medium access control (MAC) scheduling function

moved to Node-B (WCDMA packet scheduling was done in the RNC)

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 62

HSDPA amp Enhance Uplink

bull Gain in Performance

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 63

HSDPA

bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to

individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes

bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)

12 64

HSDPA

bull New frame structurendash Five subframesW-CDMA

framendash User data can be

assigned on a subframe basis

ndash System can adjust in 2ms

ndash Each subframe is a transmission time interval (TTI) = 2ms

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 65

HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared

resource is also in the time domain

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 66

HSDPA

bull Another view

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

Spreading Code

12 67

HSDPAbull Link Adaptation

ndash Remember the fast power control is commonly used to

bull Maintain constant EnergyNoise ratiobull Reduce effect of fading

ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant

EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 68

HSDPA

ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)

ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum

bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user

bull 1 ndash 2 Mbs closer to achievable under real conditions

12 69

HSDPA

bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE

bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms

bull CQI (0-30) each mapping into a modulation SF etc

bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression

bull

12 70

HSDPA

bull Schedulingndash The scheduler decides which user

should get access to each TTI ndash CQI provides input into a Scheduler

bull Proportional Fair (PF) Scheduler can be uses

bull Implementation Specific

12 71

HSDPA

bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number

of spreading codes limits rate not power so likely receive first transmission

ndash At greater distances move from BS see more errors IR will require additional transmission but not many

ndash HARQ only retransmit upon an ACK or NACK

12 72

HSDPA

From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007

12 73

HSDPA

bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2

ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent

Scheduling

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 62

HSDPA amp Enhance Uplink

bull Gain in Performance

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 63

HSDPA

bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to

individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes

bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)

12 64

HSDPA

bull New frame structurendash Five subframesW-CDMA

framendash User data can be

assigned on a subframe basis

ndash System can adjust in 2ms

ndash Each subframe is a transmission time interval (TTI) = 2ms

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 65

HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared

resource is also in the time domain

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 66

HSDPA

bull Another view

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

Spreading Code

12 67

HSDPAbull Link Adaptation

ndash Remember the fast power control is commonly used to

bull Maintain constant EnergyNoise ratiobull Reduce effect of fading

ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant

EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 68

HSDPA

ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)

ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum

bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user

bull 1 ndash 2 Mbs closer to achievable under real conditions

12 69

HSDPA

bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE

bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms

bull CQI (0-30) each mapping into a modulation SF etc

bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression

bull

12 70

HSDPA

bull Schedulingndash The scheduler decides which user

should get access to each TTI ndash CQI provides input into a Scheduler

bull Proportional Fair (PF) Scheduler can be uses

bull Implementation Specific

12 71

HSDPA

bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number

of spreading codes limits rate not power so likely receive first transmission

ndash At greater distances move from BS see more errors IR will require additional transmission but not many

ndash HARQ only retransmit upon an ACK or NACK

12 72

HSDPA

From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007

12 73

HSDPA

bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2

ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent

Scheduling

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 63

HSDPA

bull Shared transmission mechanismbull Definition of a new ldquochannelrdquobull High-speed downlink shared channel (HS-DSCH) bull The HS-DSCH is dynamically use to transmit to

individual usersndash Supports link adaptation hybrid ARQ and schedulingndash Always associated with a DPCH ndash Never in soft handoverndash Mapped to one or several channelization codes

bull An associated control channel is also defined bull High Speed- shared control channel (HS-SCCH)

12 64

HSDPA

bull New frame structurendash Five subframesW-CDMA

framendash User data can be

assigned on a subframe basis

ndash System can adjust in 2ms

ndash Each subframe is a transmission time interval (TTI) = 2ms

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 65

HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared

resource is also in the time domain

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 66

HSDPA

bull Another view

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

Spreading Code

12 67

HSDPAbull Link Adaptation

ndash Remember the fast power control is commonly used to

bull Maintain constant EnergyNoise ratiobull Reduce effect of fading

ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant

EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 68

HSDPA

ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)

ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum

bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user

bull 1 ndash 2 Mbs closer to achievable under real conditions

12 69

HSDPA

bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE

bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms

bull CQI (0-30) each mapping into a modulation SF etc

bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression

bull

12 70

HSDPA

bull Schedulingndash The scheduler decides which user

should get access to each TTI ndash CQI provides input into a Scheduler

bull Proportional Fair (PF) Scheduler can be uses

bull Implementation Specific

12 71

HSDPA

bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number

of spreading codes limits rate not power so likely receive first transmission

ndash At greater distances move from BS see more errors IR will require additional transmission but not many

ndash HARQ only retransmit upon an ACK or NACK

12 72

HSDPA

From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007

12 73

HSDPA

bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2

ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent

Scheduling

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 64

HSDPA

bull New frame structurendash Five subframesW-CDMA

framendash User data can be

assigned on a subframe basis

ndash System can adjust in 2ms

ndash Each subframe is a transmission time interval (TTI) = 2ms

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

12 65

HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared

resource is also in the time domain

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 66

HSDPA

bull Another view

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

Spreading Code

12 67

HSDPAbull Link Adaptation

ndash Remember the fast power control is commonly used to

bull Maintain constant EnergyNoise ratiobull Reduce effect of fading

ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant

EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 68

HSDPA

ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)

ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum

bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user

bull 1 ndash 2 Mbs closer to achievable under real conditions

12 69

HSDPA

bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE

bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms

bull CQI (0-30) each mapping into a modulation SF etc

bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression

bull

12 70

HSDPA

bull Schedulingndash The scheduler decides which user

should get access to each TTI ndash CQI provides input into a Scheduler

bull Proportional Fair (PF) Scheduler can be uses

bull Implementation Specific

12 71

HSDPA

bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number

of spreading codes limits rate not power so likely receive first transmission

ndash At greater distances move from BS see more errors IR will require additional transmission but not many

ndash HARQ only retransmit upon an ACK or NACK

12 72

HSDPA

From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007

12 73

HSDPA

bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2

ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent

Scheduling

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 65

HSDPAbull HS-DSCH structure both Code sharing and TDMbull SF=16bull 15 different spreading codesbull UE can send on multiple codes in a TTIbull Main difference with W-CDMA is that the shared

resource is also in the time domain

From Stefan Parkvall Eva Englund Magnus Lundevall and Johan Torsner ldquoEvolving 3G Mobile Systems Broadband and Broadcast Services in WCDMArdquo IEEE Communications Magazine February 2006

12 66

HSDPA

bull Another view

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

Spreading Code

12 67

HSDPAbull Link Adaptation

ndash Remember the fast power control is commonly used to

bull Maintain constant EnergyNoise ratiobull Reduce effect of fading

ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant

EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 68

HSDPA

ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)

ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum

bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user

bull 1 ndash 2 Mbs closer to achievable under real conditions

12 69

HSDPA

bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE

bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms

bull CQI (0-30) each mapping into a modulation SF etc

bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression

bull

12 70

HSDPA

bull Schedulingndash The scheduler decides which user

should get access to each TTI ndash CQI provides input into a Scheduler

bull Proportional Fair (PF) Scheduler can be uses

bull Implementation Specific

12 71

HSDPA

bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number

of spreading codes limits rate not power so likely receive first transmission

ndash At greater distances move from BS see more errors IR will require additional transmission but not many

ndash HARQ only retransmit upon an ACK or NACK

12 72

HSDPA

From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007

12 73

HSDPA

bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2

ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent

Scheduling

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 66

HSDPA

bull Another view

From Agilent Applications noteConcepts of High Speed Downlink Packet AccessBringing Increased Throughput and Efficiency to W-CDMA

Spreading Code

12 67

HSDPAbull Link Adaptation

ndash Remember the fast power control is commonly used to

bull Maintain constant EnergyNoise ratiobull Reduce effect of fading

ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant

EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 68

HSDPA

ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)

ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum

bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user

bull 1 ndash 2 Mbs closer to achievable under real conditions

12 69

HSDPA

bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE

bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms

bull CQI (0-30) each mapping into a modulation SF etc

bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression

bull

12 70

HSDPA

bull Schedulingndash The scheduler decides which user

should get access to each TTI ndash CQI provides input into a Scheduler

bull Proportional Fair (PF) Scheduler can be uses

bull Implementation Specific

12 71

HSDPA

bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number

of spreading codes limits rate not power so likely receive first transmission

ndash At greater distances move from BS see more errors IR will require additional transmission but not many

ndash HARQ only retransmit upon an ACK or NACK

12 72

HSDPA

From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007

12 73

HSDPA

bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2

ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent

Scheduling

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 67

HSDPAbull Link Adaptation

ndash Remember the fast power control is commonly used to

bull Maintain constant EnergyNoise ratiobull Reduce effect of fading

ndash This is suitable for constant bit rate transmissionsndash Here bit rate can change introducing delayndash Changing bit rate can also maintain constant

EnergyNoise while keeping the tx power constant ndash The is called link rate adaptation

From WCDMA EvolvedHigh Speed Downlink Packet Access Mechanismsand Capabilities Alexander Wang wwwpccaorgstandardsarchitecturehsdpapdf

12 68

HSDPA

ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)

ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum

bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user

bull 1 ndash 2 Mbs closer to achievable under real conditions

12 69

HSDPA

bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE

bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms

bull CQI (0-30) each mapping into a modulation SF etc

bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression

bull

12 70

HSDPA

bull Schedulingndash The scheduler decides which user

should get access to each TTI ndash CQI provides input into a Scheduler

bull Proportional Fair (PF) Scheduler can be uses

bull Implementation Specific

12 71

HSDPA

bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number

of spreading codes limits rate not power so likely receive first transmission

ndash At greater distances move from BS see more errors IR will require additional transmission but not many

ndash HARQ only retransmit upon an ACK or NACK

12 72

HSDPA

From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007

12 73

HSDPA

bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2

ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent

Scheduling

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 68

HSDPA

ndash Bit rate changed by usingbull QPSK (2 bits per symbol time)Orbull 16 QAM (4 bits per symbol time)

ndash Modulation selected every 2 msndash Number of codes assigned selected every 2 msndash (Bit ratecode) codes = bit ratendash Theoretical maximum

bull Largest transport block = 27952 bit in 2ms = 139Mbs consumes most of cellrsquos resources for one user

bull 1 ndash 2 Mbs closer to achievable under real conditions

12 69

HSDPA

bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE

bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms

bull CQI (0-30) each mapping into a modulation SF etc

bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression

bull

12 70

HSDPA

bull Schedulingndash The scheduler decides which user

should get access to each TTI ndash CQI provides input into a Scheduler

bull Proportional Fair (PF) Scheduler can be uses

bull Implementation Specific

12 71

HSDPA

bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number

of spreading codes limits rate not power so likely receive first transmission

ndash At greater distances move from BS see more errors IR will require additional transmission but not many

ndash HARQ only retransmit upon an ACK or NACK

12 72

HSDPA

From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007

12 73

HSDPA

bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2

ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent

Scheduling

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 69

HSDPA

bull To assign a modulation and bit ratecode the BS (Node B) needs some link quality feed back from the UE

bull Each UE regularly transmits Channel Quality Indicator (CQI) to the BSndash Configurablendash Can be every 2 ms

bull CQI (0-30) each mapping into a modulation SF etc

bull Note the ldquobetterrdquo UErsquos can ask for higher CQIrsquos eg a UE with interference suppression

bull

12 70

HSDPA

bull Schedulingndash The scheduler decides which user

should get access to each TTI ndash CQI provides input into a Scheduler

bull Proportional Fair (PF) Scheduler can be uses

bull Implementation Specific

12 71

HSDPA

bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number

of spreading codes limits rate not power so likely receive first transmission

ndash At greater distances move from BS see more errors IR will require additional transmission but not many

ndash HARQ only retransmit upon an ACK or NACK

12 72

HSDPA

From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007

12 73

HSDPA

bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2

ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent

Scheduling

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 70

HSDPA

bull Schedulingndash The scheduler decides which user

should get access to each TTI ndash CQI provides input into a Scheduler

bull Proportional Fair (PF) Scheduler can be uses

bull Implementation Specific

12 71

HSDPA

bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number

of spreading codes limits rate not power so likely receive first transmission

ndash At greater distances move from BS see more errors IR will require additional transmission but not many

ndash HARQ only retransmit upon an ACK or NACK

12 72

HSDPA

From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007

12 73

HSDPA

bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2

ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent

Scheduling

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 71

HSDPA

bull Hybrid ARQ (HARQ)ndash Uses incremental redundancy (IR)ndash Note when UE close the BS the number

of spreading codes limits rate not power so likely receive first transmission

ndash At greater distances move from BS see more errors IR will require additional transmission but not many

ndash HARQ only retransmit upon an ACK or NACK

12 72

HSDPA

From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007

12 73

HSDPA

bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2

ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent

Scheduling

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 72

HSDPA

From Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-HSDPA Systems CRC Press 2007

12 73

HSDPA

bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2

ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent

Scheduling

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 73

HSDPA

bull Key conceptsndash Shared Channel Transmissionndash Higher order Modulationndash Short Transmission Time Interval (2

ms)ndash Fast Hybrid ARQ with Soft Combiningndash Fast Link Adaptationndash Fast Radio Channel Dependent

Scheduling

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 74

Enhance Uplink (HSUPA)

bull Enhanced dedicated channel (E-DCH)bull Needs power control for near-far

problem so no higher order modulation can not trade off data rate for EN

bull Shared resource is CDMA interference at the BS (Node B) desire to maintain a target interference level at Node B

bull Interference a fuction ofndash UE SF data rate (higer rate more interference)ndash UE transmission time

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 75

Enhance Uplink (HSUPA)

bull A scheduler is used to control ndash When each UE transmitsndash What rate each UE transmits at

bull Goal of the scheduler is to assign resource to those UEs with data to send

bull There are two types of grantsndash The Absolute Grants provide an absolute limitation of

the maximum amount of UL resources the UE may use

ndash The Relative Grants increase or decrease the resource limitation compared to the previously used value

bull UE sends scheduling requests withndash Available Tx powerndash UE buffer statendash Priority of buffered data (to provide QoS)

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 76

Enhance Uplink (HSUPA)

bull BS (Node B) sends scheduling grantsndash BS knows

bull Instantaneous interference levelbull All requests

ndash Then determines which grants to sent

bull This resource allocation scheme more efficient for bursty traffic allowing more liberal connection admission control

bull HARQ is also used on the uplink

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 77

References 12bull Attar R et al Evolution of cdma2000 cellular networks

multicarrier EV-DO Communications Magazine IEEE 2006 44(3) p 46-53

bull Bhushan N et al CDMA2000 1xEV-DO revision a a physical layer and MAC layer overview Communications Magazine IEEE 2006 44(2) p 37-49

bull Ekstrom H et al Technical solutions for the 3G long-term evolution Communications Magazine IEEE 2006 44(3) p 38-45

bull Guangyi L et al Evolution map from TD-SCDMA to FuTURE B3G TDD Communications Magazine IEEE 2006 44(3) p 54-61

bull Parkvall S et al Evolving 3G mobile systems broadband and broadcast services in WCDMA Communications Magazine IEEE 2006 44(2) p 30-36

bull Sanjiv Nanda KB Sarath Kumar Adaptation Techniques in Wireless Packet Data Services IEEE Communications Magazine 2000(1) p 54-64

bull Sarikaya B Packet mode in wireless networks overview of transition to third generation Communications Magazine IEEE 2000 38(9) p 164-172

bull Yavuz M et al VoIP over cdma2000 1xEV-DO revision A Communications Magazine IEEE 2006 44(2) p 50-57

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007

12 78

References 12bull Leon-Garcia amp Widjaja Communication Networks McGraw

Hill 2004bull wwwccsneueduhomerrajG250ProjectsNachiketMehtapptbull M D Yacoub Wireless Technology Protocols Standards and

Techniques CRC Press 2002bull Geert Heijenk

wwwhomecsutwentenl~heijenkmwnslidesLecture-520620slides20per20pagepdf

bull Juan J Alcaraz Fernando Cerdan and Joan Garciacutea-Haro ldquoOptimizing TCP and RLC Interaction in the UMTS Radio Access Networkrdquo IEEE Network bull MarchApril 2006

bull httpwwwumtsworldcomtechnologyRCC_stateshtmbull P Chong

wwwcomlabhutfiopetus238lecture9_PacketAccesspdfbull Agilent Applications note Concepts of High Speed Downlink

Packet Access Bringing Increased Throughput and Efficiency to W-CDMA

bull Alexander Wang WCDMA Evolved High Speed Downlink Packet Access Mechanisms and Capabilities wwwpccaorgstandardsarchitecturehsdpapdf

bull Mohamad Assaad Zeghlache Djamal TCP Performance Over UMTS-Hsdpa Systems CRC Press 2007