00-WCDMA HSDPA Principles
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Transcript of 00-WCDMA HSDPA Principles
www.huawei.com
Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Giới thiệu HSDPA
ISSUE 1.0
Page2Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Contents
1.1. Khái niệm về HSDPA Khái niệm về HSDPA
2. Các kỹ thuật cho HSDPA
Page4Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Phiên bản 99 Dữ liệu gói Dữ liệu gói được xử lý thế nào trong phiên bản 99 (FDD)
DCH ( Kênh được gán ) Mã trải phổ được gán cho mỗi người dùng Vòng điều khiển công suất kín Chuyển giao mềm
FACH ( Kênh chung ) Mã trải phổ chung Không có vòng điều khiển công suất kín Không có chuyển giao mềm
Page5Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
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
Page6Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
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
Page7Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
High Speed Downlink Packet Access (HSDPA) 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 )
Page8Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
High Speed Downlink Packet Access (HSDPA) Comparison Summary
Page9Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Contents
1. HSDPA Concepts
2.2. HSDPA Key TechniquesHSDPA Key Techniques
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HSDPA Key Techniques
AMC (Adaptive Modulation & Coding)
Data rate adapted to radio condition on 2ms
Fast Scheduling based on CQI and fairness
Scheduling of user on 2ms
HARQ( Hybrid automatic repeat request ) with Soft com
bing Reduce round trip time
16QAM16QAM in complement to
QPSK for higher peak bit rates
SF16, 2ms and CDM/TDMDynamic shared in Time and code
domain
3 New Physical Channels
Block 1
Block 2
Block 1
Block 1?
Block 1
Block 1? +
Page11Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
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
Page12Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
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 every 2ms or more cycle
NodeB selects modulation scheme ,data block size based on CQI
Bad channel condition→ More power Node B Node B
Power Control
Rate Adaptation
Good channel condition
Bad channel condition
Good channel condition
→ less power
→ low data rate
→ high data rate
Page13Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
CQI mapping table for UE category 10
CQI valueCQI valueTransport Transport Block SizeBlock Size
Number of Number of HS-PDSCHHS-PDSCH
ModulationModulationReference power Reference power
adjustment adjustment
00 N/AN/A Out of rangeOut of 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 16-QAM16-QAM 00
1717 41894189 55 16-QAM16-QAM 00
1818 46644664 55 16-QAM16-QAM 00
………… ………… ………… ………… …………
2828 2337023370 1515 16-QAM16-QAM 00
2929 2422224222 1515 16-QAM16-QAM 00
3030 2555825558 1515 16-QAM16-QAM 00
Page14Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
HSDPA UE CategoriesUE Category Maximum
Number of HS-DSCH Codes Received
Minimum Inter-TTI Interval
Maximum Number of Bits of an HS-DSCH Transport Block Received Within an
HS-DSCH TTI
Total Number of Soft Channel Bits
Category 1 5 3 7298 19200Category 2 5 3 7298 28800Category 3 5 2 7298 28800Category 4 5 2 7298 38400Category 5 5 1 7298 57600Category 6 5 1 7298 67200Category 7 10 1 14411 115200Category 8 10 1 14411 134400Category 9 15 1 20251 172800Category 10 15 1 27952 172800Category 11 5 2 3630 14400Category 12 5 1 3630 28800
Page15Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
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 applied to the combined signal.
Page16Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
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
Page17Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
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 the receiver
In case of Chase combining ( CC ) each retransmission is an identical copy of the original transmission
In case of Incremental Redundancy ( IR ) each retransmission may add new redundancy
Page18Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Hybrid Automatic Repeat reQuest ( HARQ ) Example for Chase Combining ( CC ) Scheme
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Hybrid Automatic Repeat reQuest ( HARQ ) Example for Incremental Redundancy ( IR ) Scheme
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Fast Scheduling Fast scheduling is about to decided to which terminal the shared channel transmission should be directed at any given moment
Page21Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
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
Page22Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
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
Page23Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
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 utilizationAll
channelizationcodes availablefor HSDPA
Tim e
Channelizationcode
UE1 data UE2 data UE3 data
Page25Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
HSDPA New Physical Channels
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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
Page27Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
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
Page28Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Implementation of MAC-hs
HS-DPCCH demodulation and decode
SRNC(MAC-d)
power monitor
CQI adjustmen
tScheduler
Queues/flow control
HARQ
TFRC
Power managemen
t
Coding and modulation
OM parameters Power limitation
Power for HSDPA
CQI Value
Stat. Of ACK/NACKACK/NACK
Waiting time
Queue filling info Queue priority
CQI ValueCode allocation
Code available
Data flowControl signal