00-WCDMA HSDPA Principles[1]

8/7/2019 00-WCDMA HSDPA Principles[1]

1/29

www.huawei.com

Copyright 2006 Huawei Technologies Co., Ltd. All rights reserved.

Gii thiu HSDPA

ISSUE 1.0


2/29

Copyright 2006 Huawei Technologies Co., Ltd. All rights reserved. Page1

Contents

1.1. Khi nim v HSDPAKhi nim v HSDPA

2. Cc k thut cho HSDPA


3/29


WCDMA Evolution


4/29


Phin bn 99 D liu gi

D liu gi c x l th no trong phin bn 99 (FDD)

DCH ( Knh c gn )

M tri ph c gn cho mi ngi dng

Vng iu khin cng sut kn

Chuyn giao mm

FACH ( Knh chung )

M tri ph chung

Khng c vng iu khin cng sut kn

Khng c chuyn giao mm


5/29


Release 99 Downlink Limitation

Dedicated Channel Features ( DCH )

Maximum implemented downlink of 384kbps

OVSF code limitation for high data rate users

Rate switching according to burst throughput is slow

Outer loop power control responds slowly to channel

Common Channel Features ( FACH )

Good for burst data application

Only low data rates supported Fixed transmit power


6/29


High Speed Downlink Packet Access (HSDPA)

The differences between HSDPA and R99

Set of high data rate channel

Channels are shared by multiple users

Each user may be assigned all or part of the resource every 2 ms

Node B

HS-PDSCH


7/29



How will HSDPA figure out the limitations of R99

Adaptive modulation and coding

Fast feedback of Channel condition

QPSK and16QAM Channel coding rate from 1/3 to 1

Multi-code operation

Multiple codes allocated per user

Fixed spreading factor

NodeB fast Scheduling

Physical Layer HARQ ( Hybrid Automatic Repeat reQuest )


8/29



Comparison Summary


9/29


Contents

1. HSDPA Concepts

2.2. HSDPA Key TechniquesHSDPA Key Techniques


10/29


HSDPA Key Techniques

AMC (AdaptiveModulation & Coding)

Data rateadaptedto radio conditionon 2ms

Fast Scheduling basedonCQI and fairness

Schedulingofuseron 2ms

HARQHybridautomatic repeat

request with Soft combing

Reduce roundtriptime

16QAM

16QAMin complementto QPSKfor higherpeak bit rates

SF16, 2ms and CDM/TDM

Dynamic sharedinTimeand codedomain

3New Physical Channels

Block 1 Block 2Block 1

Block 1?

Block 1Block 1?

+


11/29


Adaptive Modulation and Coding ( AMC )

AMC ( Adaptive Modulation and Coding ) based on CQI ( Channel

Quality Indicator )

Adjust data rate to compensation channel condition

Good channel condition higher data rate

Bad channel condition lower data rate

Adjust channel coding rate to compensation channel condition

Good channel condition channel coding rate is higher e.g. 3/4

Bad channel condition channel coding rate is lower e.g. 1/3 Adjust the modulation scheme to compensation channel condition

Good channel condition high order modulation scheme e.g. 16QAM

Bad channel condition low order modulation scheme e.g. QPSK


12/29


Adaptive Modulation and Coding ( AMC )

AMC ( Adaptive Modulation and Coding ) based on CQI

( Channel Quality Indicator )

CQI ( channel quality indicator )

UE measures the channel quality and reports to NodeB every2ms or more cycle

NodeB selects modulation scheme ,data block size based on CQI

Bad channel condition

MorepowerNode B Node B

Power Control RateAdaptation

Good channel condition

Bad channel condition

Good channel condition less power

lowdata rate

high data rate


13/29


CQI mapping table for UE category 10

CQIvalueCQIvalueTransportTransport

Block SizeBlock Size

Number ofNumber of

HSHS--PDSCHPDSCHModulationModulation

Reference powerReference power

adjustmentadjustment((

00 N/AN/A Outof rangeOutof range

11 137137 11 QPSKQPSK 00

22 173173 11 QPSKQPSK 00

1313 22792279 44 QPSKQPSK 00

1414 25832583 44 QPSKQPSK 00

1515 33193319 55 QPSKQPSK 00

1616 35653565 55 1616--QAMQAM 00

1717 41894189 55 1616--QAMQAM 00

1818 46644664 55 1616--QAMQAM 00

2828 2337023370 1515 1616--QAMQAM 00

2929 2422224222 1515 1616--QAMQAM 00

3030 2555825558 1515 1616--QAMQAM 00


14/29


HSDPA UE Categories

UE Category MaximumNumberof HS-

DSCH CodesReceived

Minimum Inter-TTI Interval

Maximum Numberof Bits ofanHS-DSCH Transport Block

Received Withinan HS-DSCHTTI

TotalNumberof SoftChannel Bits

Category 1 5 3 7298 19200

Category 2 5 3 7298 28800

Category 3 5 2 7298 28800

Category 4 5 2 7298 38400

Category 5 5 1 7298 57600

Category 6 5 1 7298 67200

Category 7 10 1 14411 115200

Category 8 10 1 14411 134400

Category 9 15 1 20251 172800

Category 10 15 1 27952 172800

Category 11 5 2 3630 14400

Category 12 5 1 3630 28800


15/29


Hybrid Automatic Repeat reQuest( HARQ ) Conventional ARQ

In a conventional ARQ scheme, received data blocks that can not be

correctly decoded are discarded and retransmitted data blocks are

separately decoded

Hybrid ARQ

In case of Hybrid ARQ with soft combining, received data blocks that

can not be correctly decoded are not discarded. Instead the

corresponding received signal is buffered and soft combined with later

received retransmission of information bits. Decoding is then appliedto the combined signal.


16/29


Hybrid Automatic Repeat reQuest( HARQ ) Example for HARQ

The use of HARQ with soft combining increases the effective

received Eb/Io for each retransmission and thus increases the

probability for correct decoding of retransmissions, compare to

conventional ARQ


17/29


Hybrid Automatic Repeat reQuest( HARQ ) There are many different schemes for HARQ with soft

combining.

These scheme differ in the structure of retransmissions and

in the way by which the soft combining is carried out at thereceiver

In case of Chase combining ( CC ) each retransmission is an

identical copy of the original transmission

In case of Incremental Redundancy ( IR ) each retransmissionmay add new redundancy


18/29


Hybrid Automatic Repeat reQuest( HARQ ) Example for Chase Combining ( CC ) Scheme


19/29


Hybrid Automatic Repeat reQuest( HARQ ) Example for Incremental Redundancy ( IR ) Scheme


20/29


Fast Scheduling

Fast scheduling is about to decided to which terminal the sharedchannel transmission should be directed at any given moment


21/29


Short TTI (2ms)

Shorter TTI ( Transmission Time Interval ) is to reduce RTT

( round trip time )

Shorter TTI is necessary to benefit from other functionalities

such as AMC, scheduling algorithm and HARQ


22/29


In HSDPA, a new DL transport channel is introduced call

HS-DSCH. The idea is that a part of the total downlink code

resource is dynamically shared between a set of HSDPA

users

Shared Channel Transmission


23/29


Shared Channel Transmission

The codes are assigned to HSDPA user only when they are

actually to be used for transmission, which leads to efficient

code and power utilization

Allchannelization

codes availablefor HSDPA

Time

Channelizationcode

data 2 data data


24/29


Higher-Order Modulation


25/29


HSDPA New Physical Channels


26/29


HSDPA Physical Layer Channels

New HSDPA Channels

High Speed Downlink shared Channel ( HS-DSCH )

Downlink Transport Channel

High Speed Shared Control Channel ( HS-SCCH )

Downlink Control Channel

High Speed Physical Downlink Shared Channel ( HS-PDSCH )

Downlink Physical Channel

High Speed Dedicated Physical Control Channel ( HS-DPCCH )

Uplink Control Channel


27/29


Theoretical HSDPA Maximum Data Rate

Theoretical HSDPA Maximum data rate is 14.4Mbps

How do we get to 14.4Mbps ?

Multi-code transmission

NodeB must allocate all 15 OVSF codes ( SF =16 ) to one UE

Consecutive assignments using multiple HARQ process

NodeB must allocate all time slots to one UE

UE must decode all transmission correctly on the first transmission

Low channel coding gain

Effective code rate = 1 Requires very good channel conditions to decode

16QAM

Requires very good channel condition


28/29


Implementation of MAC-hs

HS-DPCCHdemodulation anddecode

SRNC(MAC-d)

power monitor

CQI adjustment

Scheduler

Queues/flowcontrol

HARQ

TFRC

Power

management

Codingandmodulation

OMparameters

Power limitation

Power for HSDPA

CQI Value

Stat. Of ACK/NACK

ACK/NACKWaiting time

Queue filling infoQueue priority

CQI ValueCodeallocation

Code available

Data flow

Control signal


29/29

Thank YouThank You

00-WCDMA HSDPA Principles[1]

Documents

Transcript of 00-WCDMA HSDPA Principles[1]