01 hspa system overview in umts network-libre

8/10/2019 01 HSPA System Overview in UMTS Network-libre

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Nokia Siemens Networks Author Presentation Department 1

HSPA System Overview


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Objective

At the end of the module the participant will be able to:

Describe UMTS network and Radio Access Network.

Explain aspects of UMTS Release 99 air interface.

Briefly introduce HSPA system and key elements of HSPA.

Briefly introduce HSPA+ system and key elements of HSPA+.


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Content

UMTS evolution and HSPA

UMTS Release 99 environment Network

Air Interface

HSDPA introduction and advantages

HSUPA introduction and advantages

HSPA+ introduction and advantages

LTE introduction


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HSPA or HSxPA

Consists of:

HSDPA = High Speed Downlink Packet Access Introduced in Release 5

Up to 14.4 Mbps in downlink

HSUPA = High Speed Uplink Packet Access Introduced in Release 6

Up to 5.76 Mbps in uplink

Future enhancements to HSPA will lead to even higher datarates.


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Rel 99

( = Rel 3)Rel 4 Rel 5

Rel 98

(EGPRS)

RAN

CORE

UTRANQoS

HSDPA

VoIPMGW

QoSIMS

Rel 6

HSUPA

Evolution of UMTS


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Evolution of UMTS (Continued)

Rel 7 Rel 8 Rel 9Rel 6

RAN

CORE

HSPA+Rel 7

SAEDirectTunnel

HSPA+ Rel 8,LTE

???


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UMTS Release 99 Environment

Core Network: Same as GSM/GPRS/EDGE

Radio Access Network:

User Equipment (UE) = Mobile phone + USIM

Node B Base station supporting WCDMA

Radio Network Controller (RNC) Controller in 3G RAN

Unlike 2G, Iur interface exists between neighbor RNCs.


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UMTS Network

Iur

IuCS

IuPS

Iub

E

Gn Gi

UE

Uu

The picture shows Release 99 core network. In release 4 core networks, MSC is splitted into

MSC Server (MSS) and Media Gateway (MGW).


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UMTS Release 99 Air Interface

Large 5 MHz bandwidth.

FDD: Simultaneous transmit and receive using different band.

CDMA Spreading: creating signal through unique user code to create multiple

bandwidth.

Despreading: reobtaining original signal by correlating signal with usercode.


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FrequencyTime

PN code

FDMATDMA

CDMA

frequency f

time t

power

TS 1

TS 2

TS 3

TDMA

frequency f

time t

power

1 2 3

FDMA

frequency f

time t

power

1

23

CDMA

Multiplex

method

BS & MS with common

know-how regarding:

P

P P

For coordinating limited frequency

resources to different users


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-1

User data:100

0 01

T Bit

Spreading code:0110

+1

+1

-1

+1

-1

Coded signal T chip

t

t

t

SF = 4

0 0 0 0 0 01 1 1 1 1 1

0 0 0 01 1 1 11 10 0


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Spreading

CodeGenerator

WidebandModulation

CarrierGenerator

De-Spreading

CodeGenerator

De-Modulation

RB

Air

Interface

RB

RC

Time

synchronization

RB: Bit Rate

RC: Chip Rate

fT: Carrier frequency

RCfT

bits chips symbol

Transmitter Receiver


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Role of Channelization and Scrambling Code inDownlink Direction

Channelization codesdistinguish user within acell.

Each cell has the samechannelization code tree two users in differentcells can have the samechannelization codeassigned.

Therefore the differentcells must becharacterized by a

Scrambling code.

Code 3

Code 3Code 2

Code 1

Code 2

Code 1


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Code Comparison between Uplink and Downlink

4, 8, 16, 32, 64, 128, 256,

5124, 8, 16, 32, 64, 128, 256

Available

Channelisation Codes

FDD

Channelisation Code x Scrambling CodeSpreading Code

Users within a cellData and control channels

from same UEChannelisation Codes

Cell separationUser separationScrambling Codes

DownlinkUplink


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In the uplink direction theuser signals are not

synchronised due to timedelay.

In case of different timedelays ChannelizationCodes are not orthogonalany more.

Scrambling Codes: Highautocorrelation ifsynchronized, almost zerocorrelation between differentcodeseven ifunsynchronized.

Chann. Code

= (1,-1,-1,1)

Chann. Code

= (1,1,-1,-1)

T=0

1 1 -1 -1 1 1 -1 -1 1 1 -1 -1

1 -1 -1 1 1 -1 -1 1 1 -1 -1 1

Delay

t

Role of Scrambling Code in Uplink Direction


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Reserved for

signaling

2 voice

connections

7 dataconnections

3.4 kbps

SF=64

SF=8

SF=16

SF=32

SF=4

12.2 kbps

384 kbps

SF=128

SF=256

144 kbps

64 kbps

OVSF Code Tree Usage


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2560 chipsTimeslot TS

2/3 ms

Frame TS#0 TS#i TS#14

10 ms

f#1 f#i f#72 Superframe

720 ms

1/3,840,000 s 0.2604 s

ChipShortest information unit in CDMA

(of the spreading code)

Periodic repetition ofcontrol information (e.g. TPC)

Shortest transmission durationand data rate adaption

Counting period for:

Definition of physical channels Handover to GSM (120 ms frame)

Chip, Timeslot, Frame, Superframe


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HSDPA

Introduced in Release 5.

Can coexist with non-HSDPA in the same cell. Improve downlink direction. Uplink still relies on Rel '99.

Advantages:

Higher data rate: up to 14.4 Mbps with practical rate 10.8Mbps.

Reduce latency: especially with TCP Slow Start and Congestion Avoidance. Retransmission and HARQ in Node B.

Spectral efficiency: TTI=2ms schedule of shared channels.


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TCP Window Size

8,760

congestion occurs

receivers window seize

cwnd

slow start threshold, start value = 65535

slow start threshold, readjusted value

readjustment

of slow start

thresholdthird phase:

congestion voidance,

linear growth

second phase:

slow start,

eponential growthfirst phase:

slow start,

exponential growth


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Rel99 DCH

RNC RNC

Packet

Node B

Packet

Retransmission

L1 ACK / NACK

RLC ACK / NACK

Retransmission

Retransmission Cycle in HSDPA

Rel5 HS-DSCH


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HSDPA Scheduling

10 msDedicated

DCH

SharedHS-DSCH Big shared pipe

Time

Code

HSDPA

wasted bandwidth!

2 ms

inefficient usage!

Rel '99


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HSUPA

Introduced in Release 6.

Improve uplink direction. Rely on HSDPA in downlink.

Advantages:

Higher data rate: up to 5.76 Mbps with practical rate 1.44Mbps in first version.

Reduce latency: retransmission request by Node B.

Increased coverage and capacity: efficient handling of uplinkinterference problem.


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Improved Performance with HSUPA

User data rate

Round triptime, delays

Cell throughput

Coverage

20 100% improvementdepending on the channelconditions

Round trip timeapproximately 50milliseconds

Cell throughput improved by20 50%

Coverage gain 0.5 1.5dB


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HSPA+

Also called Evolved HSPA (eHSPA), HSPA Evolution

Corresponds to HSPA in Release 7 and 8

Some key features: MIMO

64QAM in downlink

16QAM in uplink

Direct tunnel

etc.


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New Features in HSPA+

64QAMModulation

TX RX

Tx Rx

MIMO

Channel

MIMO

= control plane

= user plane

GGSN

SGSN

RNC

Node-B

Direct tunnel in Rel 7


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Data Rate Evolution

Performance with 2x2 MIMO and 16QAM for Rel 7

With 2x2 MIMO and 64QAM for Rel 8LTE requires 20 MHz bandwidth for 173/58 Mbps

14 Mbps

0.4 Mbps

14 Mbps

5.7 Mbps

28 Mbps

11 Mbps

Downlinkpeakrat

e

Uplinkpeakrate

3GPP Rel5 3GPP Rel6 3GPP Rel7 3GPP Rel8

42 Mbps

11 Mbps

173 Mbps

58 Mbps

HSPA+ LTE


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HSPA+ Features and Benefits

HSPA+ is not only about the peak data rates!

Extended battery time

Continuous connectivity

Peak data rate improvements

Continuous Packet Connectivity(DTX/DRX)

CS voice over HSPA

HS-FACH, HS-RACH

Cell throughput and typicalthroughput improvements

System capacity, E2E andarchitecture efficiency

64QAM DL, MIMO2x2, MC-HSDPA, 16QAM UL

Flexible RLC in DL and UL

SRNS Relocation Enhancement,Enhancement for HSPA Arch.

Faster set-up times

3GPP Rel7/Rel8 item Impact on end userexperience


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LTE

LTE = Long Term Evolution

Part of 3GPP Release 8

Only packet switched

Intend to coexist with existing 2G/3G/HSPA networks

Major changes to: Air interface

Network architecture: SAE (System Architecture Evolution)


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LTE Principles

Flat Overall Architecture

2-node architecture

All-IP

Simplified protocol structure

Improved Radio Principles peak data rates [Mbps ]: 173 DL , 58 UL

Scalable BW: 1.4, 3, 5, 10, 15, 20 MHz

Short latency: 10 20 ms

OFDMA

Direct tunnel

Internet

Evolved Node B

MME S-GW/

PDN-GW

01 hspa system overview in umts network-libre

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