hsdpa tutorial

14.06.2006 1

HSDPA High Speed Downlink Packet Access

Technology Updateadare GmbH

www.adare.deMarija Skoda

Email: [email protected]

March 2006

14.06.2006 2

HSDPA - Agenda

GSM and UMTS evolutionGSM and UMTS evolutionTechnological approachProtocol architectureHDSPA channels in UTMS Release 5Mobility aspectsOutlook beyond Release 5

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Evolution of GSM and UMTS in Europe

Phase1 Phase2 Phase 2+

R‘96 R‘97R‘98

R‘99

R‘99

R’4R’5

R’6

R’7

2G2G 2,5G2,5G3G3G

3.5G3.5G

Increase in data transmission

speed from 2Mbps to 30-50Mbps

Phase 2+: HSCSD, GPRS, EDGE Enhanced Bearer Services

(14.4kbps-50kbps-128kbps)

UMTSUMTS

Phase 2: Tele (HR speech, SMS)/ Bearer(9.6kbps)/Supplementary Services

Phase 1: Tele (FR speech, SMS)/ Bearer(9.6kbps)/Supplementary Services

1990-1991 1994 1997 1998 1999 1999-2000 2001 2002 2005 2007

Year

GSMGSM R’99: UTRAN, WCDMA, MMS (up to 2Mbps)

R’4-R’7: VHE, IMS, HSDPA, HSUPA, PoC, E-DCH, MBMS, MIMO, WLAN integration

* See the apendix for the abbreviation list

14.06.2006 4

UMTS FDD radio access basics

Channel bandwidth 5 MHz 5 MHz QPSK modulationQPSK modulationPulse shapingPulse shapingDirect sequence CDMADirect sequence CDMAOVSF spreading codesOVSF spreading codesTiming structureTiming structureTransmission rate 3.84 Transmission rate 3.84 MchipMchip/s/sFrequency reuse = 1Frequency reuse = 1Soft handoverSoft handover

CDMACDMA – Code Division Multiple Access

OVSFOVSF – Orthogonal Variable Spreading Factor

QPSKQPSK – Quadrature Phase Shift Keying

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CDMA principle

CDMACDMA-Code Division Multiple Access:

- Narrow-band signal is spreadedspreaded with an OVSF code:to increase the signal bandwidthto achieve the orthogonality between signals from the

same source

- Wide-band signal then is scrambledscrambled with a scrambling code to distinguish between different sources

-- Spreading factorSpreading factor SF =Chiprate/Bitrate

NearNear--far problemfar problem: - power control necessary to limit the interference between sources

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Spreading example

1 symbol

1 chip

+1

Bipolar data

-1

Spreading code SF=8

(channelisationcode x scrambling

code)

+1

-1

+1

Coded data

-1

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HSDPA Motivation

Reasons to deploy HSDPA:- Saturated voice communication market- Growing demand and user expectation for the data

services like broadband internet access, streaming, gaming, etc.

- Competing High Speed wireless technologies- WLAN- WiMAX- 1xEvDo in CDMA 2000

Requirements:- Short set-up and transfer delays- High system capacity- High peak data rates- Low mobility (user speed max 3km/h)- Low data transfer costs

14.06.2006 8

Rel.´99 vs. Release 5

Release’99 Release 5 - HSDPA

High speedHigh speeddownlink

broadcast shared channel for data

Support of IP and radio bearers for IP-based services

Voice & data over DCH;

Max download rate 384 kbit/s, GPRS latency 700 ms

Mode of Transmission

Release’99 Cellsand

mixed Rel.’99 – Rel.5 cellse.g. in hotspots

NetworkView

Release’99 cells

14.06.2006 9

HSDPA - Agenda

GSM and UMTS evolutionTechnological approachTechnological approachProtocol architectureHDSPA channels in UTMS Release 5Mobility aspectsOutlook beyond Release 5

14.06.2006 10

High speed downlink broadcast channel

NodeB

HSDPA- capableUEs

Service aspect:

•Allow higher data rates for users in favourable positions

•Decrease latency

Network aspect:

•Increase radio efficiency/capacity for data

Major objectives:Major objectives:

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Technologies for HSDPA support

Adaptive Modulation and Coding (AMC)

Hybrid Automatic Repeat Request (H-ARQ)

Fast transmission/retransmission scheduling

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Adaptive Modulation and Coding (AMC)Adaptive Modulation and Coding (AMC)

Hybrid Automatic Repeat Request (H-ARQ)


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AMC principle

Power level: β

Modulation: QPSK

Turbo Code R=1/3

Power level: α

Modulation: 16-QAM

Turbo Code R=1/3,

rate matching: 3/4

Power level: α

Modulation: QPSK

Turbo Code R=1/3,rate matching: 1/4

Power level: α

Modulation: QPSK

Turbo Code R=1/3

UE1 UE1

UE2UE2

NodeBNodeB

Release ’99 HSDPAHSDPA

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Main principle – to dynamically modifySignal modulationSignal modulation and Coding schemeCoding scheme

to compensate the variations in cannel conditions

Benefits:- Increased average cell throughput- Reduced interference variation- Higher data rates for users in favourable positions

Effective in a combination with scheduling techniques

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Data throughput

9604/4

7203/4

4802/4

16-QAM

3603/4

2402/4

1201/4

QPSK

Throughput in kbps

(1 code of SF=16)

Coding RateModulation

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Hybrid Automatic Repeat Request Hybrid Automatic Repeat Request (H(H--ARQ)ARQ)


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H-ARQ-type-III

Chase combining with one redundancy version: the data are retransmitted with a little redundancyredundancy. The retransmitted signal is weighted by SNR and then combined with the first received signal.

Coded data bits with redundancy Data Bits

Error detected:store a packet, request a retransmission

Decode combined data

Data Bits

NACK

+UE

NodeB

1st transmission

2nd transmission

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H-ARQ-type-II

Incremental redundancy: only correctioncorrection data to the original data is retransmitted. The additional redundant data will be sent incrementally if NACK is received

Coded data bits with redundancy Data Bits

NACK

Error detected:store a packet, request retransmission

Combine the stored packet

with a received redundancy Decode combined data

Data Bits

UE

NodeB

14.06.2006 19

Timing structure Rel’99

In UMTS Rel’99 the transmission time interval for transport channels is always multiple to 10 ms (10/20/40/80)

2/3 ms

2560 chips

TS0 TSi TS14

F0 Fi F71

720 ms

Time Slot TSTime slot is the shortest

repetitive period

1Frame =15TS Frame is the shortest transmission duration10 ms

Superframe=72F

TTITTI--Transmission Time IntervalTransmission Time Interval

14.06.2006 20

Shorter time transmission interval (TTI)

HSDPA introduces short TTI concept, where TTI=2ms

Advantages:- Less probability of an error due to the change of

the channel conditions- More efficient when packet retransmission is

necessary- Decreased buffer size

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Hybrid Automatic Repeat Request Hybrid Automatic Repeat Request (H(H--ARQ)ARQ)


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Fast and fair scheduling in NodeB

UE1

UE2

t

P

P

CQI 1

CQI 2tScheduled Packet Buffer

Fast scheduling is based on a knowledge of an instantaneous channel quality and thus effectively avoids channel fading during the transmission of data

UE capabilities, QoS requirements, Uuresources availability are also taken into

account for the efficient scheduling

CQI-Channel Quality Indicator

NodeBData for UE1

Data for UE2

2ms

t

14.06.2006 23

HSDPA - Agenda

GSM and UMTS evolutionTechnological approachProtocol architectureProtocol architectureHDSPA channels in UTMS Release 5Mobility aspectsOutlook beyond Release 5

14.06.2006 24

Need for an architectural change to Rel’99

ARQ mechanism is placed in RNC- Disadvantage: latency time up to 100 ms!- Solution: move it to node B- Profit: latency below 10 ms

Scheduling is controlled by RNC- Disadvantage: important channel measurement

information can be delayed- Solution: move scheduling close to the air

interface- Profit: rescheduling is made within a short time

14.06.2006 25

New protocol entities

PHY PHY

MAC hs

MAC hs

MAC c/sh

MAC c/sh

HS-DSCH

FP

HS-DSCH

FP

L1 L1

L2 L2

MAC d MAC d

RLC

PDCP

RLC

PDCP

Slow handshake

(RLC acknowledged mode)

NodeBUE RNC

Fast handshake

Uu Iub/Iur

14.06.2006 26

Impact on the network

New type of cell – Rel’5 cell, complement to Rel’99 cell and ensures HSDPA functioning

New NodeB fast scheduling functionality that takes into account- Buffer status and resource availability- QoS and priority- UE capabilities and quality feedback

Flow control mechanism on the Iub interface

14.06.2006 27

HSDPA - Agenda

GSM and UMTS evolutionTechnological approachProtocol architectureHDSPA channels in UTMS Release 5HDSPA channels in UTMS Release 5Mobility aspectsOutlook beyond Release 5

14.06.2006 28

HSDPA code allocation example

Other channels

HSHS--DSCHDSCH – High Speed Downlink Shared Channel

SF=1

SF=2

SF=4

SF=8

SF=16

HS-DSCH

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HSPDA multiplexing

2 ms

Data for UE1

Time Domain

Cod

e D

omai

n

TTI = 2ms

Data for UE2

Data for UE3

15

Users share channel resources in time domain and code domain.

Control channel is needed to transmit a resource allocation

information

14.06.2006 30

Data throughput

14.49.64.84/4

10.77.23.63/4

7.24.82.42/4

16-QAM

5.43.61.83/4

3.62.41.22/4

1.81.20.61/4

QPSK

Throughput in Mbps

(15 codes)

Throughput in Mbps

(10 codes)

Throughput in Mbps

(5 codes)Coding RateModulation

14.06.2006 31

Throughput calculation example

Calculate user data throughput in Mbps for a given transmission parameters:- Modulation: 16-QAM - Effective code rate: R=3/4- Number of allocated codes: N=5

Formula:

Calculation:

Chips per Sec x Number of Bits per Modulation Symbol x R x NChips per Sec x Number of Bits per Modulation Symbol x R x NSF SF

2560 x 3/2 ms x 4 x 3/4 x 5

16= 3.6 Mbps

14.06.2006 32

HSDPA terminal classes

1.8

0.9

14.4

10.8

7.2

7.2

3.6

3.6

1.8

1.8

1.2

1.2

Peak rateMbps

28800QPSK1512

14400QPSK1511

172800both21510

172800both1159

134400both1108

1152100both1107

67200both156

57600both155

38400both254

28800both253

28800both352

19200both351

Soft channel bits

ModulationMin TTIHS-DSCH channels

Class

14.06.2006 33

Channel set comparison

DSCH

HS-DSCH

HS-DCCH

HS-SCCHUE

Rel’99UE

Rel’5

Dedicated channels Dedicated channels

Shared channels Shared channels

DCH DCH

Release ‘99Release ‘99 HSDPA HSDPA

14.06.2006 34

Associated Signalling

Uplink:- Fast link adaptation (AMC) signalling- H-ARQ signalling

Downlink:- UE-Id for a given HSDPA TTI- Transport Format and Resource Indicator (TFRI):

- TB set size- Channelisation codes- H-ARQ information

- Relative CPICH to HSDPA power ratio (for TTI)

CPICHCPICH – Common Pilot Channel

14.06.2006 35

Packet exchange

N slotsN slots

7.5 slots7.5 slotsACK/NACK CQI

Data bits

UE NodeB

HS-DSCH frame

HS-DCCH frame

Time between Time between transmission of HStransmission of HS--

SCCH and HSSCCH and HS--DSCH framesDSCH framesUE-id, codes,

modulation H-ARQ information, CRCHS-SCCH frame

2 slots2 slots

Time for packet Time for packet scheduling based scheduling based

on received on received informationinformation2 slots =

1.33ms

UE-id, codes, modulation H-ARQ information, CRCTime for a Time for a

feedback feedback information information generationgeneration 1 slot =

0.67mst

t

14.06.2006 36

HSDPA - Agenda

GSM and UMTS evolutionTechnological approachProtocol architectureHDSPA channels in UTMS Release 5 Mobility AspectsMobility AspectsOutlook beyond Release 5

14.06.2006 37

Mobility management

Only hard handover hard handover for HSDPA transmissionsfor HSDPA transmissions

HSDPA handover types:- Intra NodeB handover- Inter NodeB handover- HS-DSCH to Dedicated Channel handover

14.06.2006 38

Intra-NodeB HSDPA handover

UESource Serving HS-DSCH Cell Target Serving HS-DSCH Cell

NodeB

No need to reset MAC-hs entity

If necessary, the radio bearer reconfiguration procedure

should be performed

At activation time

HS-DSCHHS-DSCH

DC

H

HS-SCCH

HS-S

CCH

S-RNC

S-RNC commands NodeB to prepare for the serving HS-DSCH cell change at the activation time

14.06.2006 39

Inter-NodeB HSDPA handover

HS-DSCH HS-DSCH

DCH DCH

HS-SCCH HS-SCCH

At activation time

NodeBNodeB

RLC for a transmission reception on HS-DSCH is stopped both at UE and UTRAN prior to and until the reconfiguration is completed

UESource Serving HS-DSCH Cell Target Serving HS-DSCH Cell

Transport channel reconfiguration message includes MAC-hs reset flag

S-RNC

14.06.2006 40

HSDPA - Agenda

GSM and UMTS evolutionTechnological approachHDSPA channels in UTMS Release 5Protocol architecturePhysical layer modificationsOutlook beyond Release 5Outlook beyond Release 5

14.06.2006 41

High speed downlink broadcast channel

NodeB

Service aspect:Higher data rated for users in favourable positionsDecrease delays

Network aspect:Increase throughput in the uplinkDownward compatibility to Rel’99, Rel’4 and Rel’5Soft handover

HSUPA- capableUEs

Need to deploy an Enhanced Dedicated Channel (EE--DCHDCH) in UL/DL for UE for scheduling and H-ARQ operations

Major objectives:Major objectives:

14.06.2006 42

MIMO example

Despread

Despread

Despread

Spread

Spread

Spread

DeMUX MUX

Detector

Detector

Detector

Space-time rake combiner……

Sender Receiver

IN OUT

MIMO technique allows to achieve higher data rates either:

when using the same spreading code on different antennasattaining better channel quality by improved antenna transmit and receive diversity

14.06.2006 43

HSPDA in Germany, Sample March 2006

Commercial offer T-Mobile (1,8 Mbit/s),large city coverageTariff example:

5 € p.m. Data Connect +35 € p.m. Option web'n'walk i.e. incl. 5 GB (quasi-flat)+1 € p.d. used

Notebook card 1 €24 month contract

UEs availability:

Today:Only notebook cards(1,8 Mbit/s)

HSDPA Mobiles announced for Summer: e.g. BenQ EF 91(3,6 Mbit/s)

Vodafone: - Home zone DSL-like tariff e.g. 36 €, incl.5 GB p.m.- Surcharge for mobility

14.06.2006 44

Questions and Discussion

Thank youThank you

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