umt irc app 016664 - hsdpa engineering guide v01.06 ext nortel

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HSDPA Engineering Guide

Document number: UMT/IRC/APP/016664Document issue: 01.06 / ENDocument status: Preliminary

Date: 20/Jan/2006

External Document

Copyright 2005 Nortel Networks, All Rights Reserved.

Printed in France

NORTEL CONFIDENTIAL

The information contained in this document is the property of Nortel Networks. Except as specifically authorized in

writing by Nortel Networks, the holder of this document shall keep the information contained herein confidential

and shall protect same in whole or in part from disclosure and dissemination to third parties and use same forevaluation, operation and maintenance purposes only.

The content of this document is provided for information purposes only and is subject to modification. It does not

constitute any representation or warranty from Nortel Networks as to the content or accuracy of the information

contained herein, including but not limited to the suitability and performances of the product or its intended

application.

This is the Way. This is Nortel, Nortel, the Nortel logo, and the Globemark are trademarks of Nortel Networks. All

other trademarks are the property of their owners.


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UMT/IRC/APP/016664 01.06 / EN Preliminary 20/Jan/2006 Page 2/141

PUBLICATION HISTORY

20/Jan/2005

Issue 01.06 / EN, Preliminary

Document update / UA4.2 CuR

25/Nov/2005

Issue 01.05 / EN, Draft

Document update / External Version

18/Oct/2005


Document updated after review for external version / External Version

04/Oct/2005


Document updated for W.39 Load / External Version

02/Sep/2005


Document updated after review

19/Aug/2005


Document Creation


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CONTENTS

1 INTRODUCTION............................................................................................................................88H

91.1 OBJECT....................................................................................................................................89H9

1.2 SCOPE OF THIS DOCUMENT .......................................................................................................90H9

1.3 NOMENCLATURE.......................................................................................................................91H9

2 RELATED DOCUMENTS............................................................................................................92H11

2.1 REFERENCE DOCUMENTS ........................................................................................................93H11

3 HSDPA OVERVIEW ....................................................................................................................94H12

3.1 SYSTEM OVERVIEW .................................................................................................................95H

123.1.1 New transport and physical channels ...........................................................................96H143.1.2 Fast link adaptation.......................................................................................................97H163.1.3 Fast Retransmission Mechanism (HARQ)....................................................................98H173.1.4 Fast scheduling.............................................................................................................99H22

3.2 DEPLOYEMENT SCENARIOS .....................................................................................................100H26

3.2.1 Dual Carrier ...................................................................................................................101H263.2.2 Single carrier.................................................................................................................102H27

3.3 HSDPARESOURCES..............................................................................................................103H27

3.3.1 OVSF Codes.................................................................................................................104H273.3.2 Power ............................................................................................................................105H283.3.3 HSDPA Channels & CQI...............................................................................................106H29

3.4 UECATEGORIES ....................................................................................................................107H36

3.5 CALL MANAGEMENT................................................................................................................108H37

3.5.1 Traffic segmentation......................................................................................................109H383.5.2 HSDPA CAC .................................................................................................................110H413.5.3 Call Setup (Dataflow) ....................................................................................................111H433.5.4 Call Release (Dataflow) ................................................................................................112H453.5.5 HSDPA related Transitions ...........................................................................................113H46

4 HSDPA CONFIGURATION .........................................................................................................114H51

4.1 RANMODEL AND PARAMETERS ..............................................................................................115H51

4.1.1 RRM Impact ..................................................................................................................116H

514.1.2 BTS Impact....................................................................................................................117H644.1.3 IuB Impact.....................................................................................................................118H65

4.2 HSDPAACTIVATION...............................................................................................................119H66

6 UA4.2 HSDPA SPECIFIC FEATURES & IMPACT ON EXISTING ALGORITHMS...................120H68

6.1 ALWAYS ON ...........................................................................................................................121H68

6.1.1 Mechanism....................................................................................................................122H686.1.2 Activation & Mode .........................................................................................................123H686.1.3 Reminder for timer usage..............................................................................................124H726.1.4 Parameters Settings and Recommendations ...............................................................125H72

6.2 IRMALGORITHMS...................................................................................................................126H73

6.2.1 Irm Scheduling Downgrade/Upgrade Interworking .......................................................127H736.2.2 iRM Cac/iRM Pre-Emption Interworking .......................................................................128H73


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6.2.3 RB Adaptation Interworking ..........................................................................................129H736.3 MOBILITY PROCEDURES ..........................................................................................................130H73

6.3.1 Intra-Frequency Mobility................................................................................................131H746.3.2 Inter-Frequency Mobility................................................................................................132H766.3.3

Inter-System Mobility.....................................................................................................133H76

6.3.4 U-Plane Traffic Handling...............................................................................................134H776.3.5 Summary of inter-frequency and inter-RAT scenarios..................................................135H78

6.4 POWER MANAGEMENT ............................................................................................................136H78

6.4.1 Introduction....................................................................................................................137H786.4.2 Flexible power management feature.............................................................................138H786.4.3 HS-SCCH power control feature...................................................................................139H946.4.4 Parameters Settings and Recommendations ...............................................................140H95

6.5 TRANSPORT ...........................................................................................................................141H98

6.5.1 Iub Bandwidth Limitation: Why this feature is needed?................................................142H986.5.2 Feature Description.......................................................................................................143H996.5.3 Case of Drift Iur .......................................................................................................... 144H101

6.5.4 Parameters Settings and Recommendations ............................................................145H

102

7 HSDPA THROUGHPUT OPTIMIZATION ................................................................................ 146H108

7.1 POWERALLOCATION AND USER THROUGHPUT...................................................................... 147H108

7.2 CQISELECTION AT UE ........................................................................................................ 148H111

7.3 CQI ADJUSTMENT BASED ON BLER...................................................................................... 149H111

7.4 BTS CREDIT ALLOCATION ..................................................................................................... 150H113

7.5 HARQ RETRANSMISSIONS ................................................................................................... 151H113

7.6 RLCSETTINGS FOR ULDCH............................................................................................... 152H114

7.7 DLRLC SETTINGS FOR HSDPA........................................................................................... 153H117

7.8 OPTIMISED TCP SETTINGS ................................................................................................... 154H117

7.9 PARAMETERS SETTINGS ...................................................................................................... 155H118

8 HSDPA CAPACITY ASPECTS ................................................................................................ 156H119

8.1 CEMCAPACITY ................................................................................................................... 157H119

8.1.1 Product limits.............................................................................................................. 158H1198.1.2 Capacity analysis ....................................................................................................... 159H119

9 PRODUCT RECOMMENDATIONS.......................................................................................... 160H129

9.1 HSDPA COMPATIBILITY WITH UTRANNETWORK ELEMENTS .................................................161H

1299.1.1 RNC............................................................................................................................ 162H1299.1.2 BTS ............................................................................................................................ 163H129

9.2 HSDPA COMPATIBILITY WITH MODULES ............................................................................... 164H130

9.2.1 RNC............................................................................................................................ 165H1309.2.2 BTS ............................................................................................................................ 166H130

9.3 HSDPASYSTEMIMPACT................................................................................................ 167H131

9.3.1 RNC functions............................................................................................................ 168H1319.3.2 BTS functions............................................................................................................. 169H131

9.4 HSDPA AND UTRANINTERFACES ...................................................................................... 170H135

9.4.1 Radio Interface........................................................................................................... 171H135

9.4.2 IuB..............................................................................................................................172H

1359.4.3 Iu-CS .......................................................................................................................... 173H1369.4.4 Iu-PS .......................................................................................................................... 174H136


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9.4.5 Iu-R............................................................................................................................. 175H1369.4.6 Iu-PC .......................................................................................................................... 176H136

10 ABBREVIATIONS AND DEFINITIONS.................................................................................... 177H137

10.1 ABBREVIATIONS

...................................................................................................................178H

13710.2 DEFINITIONS........................................................................................................................ 179H140


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TABLES

0HTable 1: Number of processes per UE category 180H171H

Table 2: RV coding for 16QAM181H

182HTable 3: RV coding for QPSK 182H183HTable 4: RV update table in the MIR case (Trv[i]) 183H194HTable 5: RV update table in the PIR case (Trv[i]) 184H195HTable 6: UE capabilities 185H376HTable 7: RB Configuration and system behaviour 186H387HTable 8: RRC Connection Request and suitable layer 187H408HTable 9: HSDPA related Transitions 188H479HTable 10 : Always-on timer usage 189H7210HTable 11: CQI update summary 190H9111HTable 12: CQI Mapping 191H9212HTable 13: HS-SCCH power offset table according the averaged CQI 192H9513HTable 14: UL rate required vs. DL rate 193H11714HTable 15: Parameters summary for optimized throughput 194H11815HTable 16: H-BBU limitations 195H119


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FIGURES

16HFigure 1: R99 principle .......................................................... ................................................................... ............ 196H1217H

Figure 2: HSDPA principle...................................................................................................................................197H

1218HFigure 3: HSDPA layer2/layer1 flows ............................................................ ...................................................... 198H1319HFigure 4: Mac-hs entity on UTRAN side.............................................................................................................. 199H1320HFigure 5: Transport channel configuration............................................................................................................ 200H1521HFigure 6: HSDPA channels and associated R99 channels..................................................................................... 201H1522HFigure 7: Example of AMC : Throughput versus Ior/Ioc (radio condition) .......................................................... 202H1623HFigure 8: RV parameters assignment algorithm.................................................................................................... 203H2024HFigure 9: ACK/NACK/DTX management for HARQ processes.......................................................... ................ 204H2125HFigure 10: Scheduler overview ................................................................. ............................................................ 205H2326HFigure 11: HSDPA on dedicated layer.................................................................................................................. 206H2627HFigure 12: Example of OVSF tree usage with HSDPA ............................................................................ ............ 207H2728HFigure 13: OVSF allocation strategy..................................................................................................................... 208H2829HFigure 14: Timing relationship at NodeB between physical channels ................................................................. . 209H2930HFigure 15: HS-SCCH structure ............................................................................ ................................................. 210H3031HFigure 16: HS-PDSCH structure........................................................................................................................... 211H3032HFigure 17: HS-DPCCH structure ................................................................... ....................................................... 212H3133HFigure 18: CQI Processing.................................................................................................................................... 213H3234HFigure 19: CQI offset computation based on BLER ..................................................................... ........................ 214H3435HFigure 20: Scheduler and Flow Control disabled.................................................................................................. 215H3636HFigure 21: HSDPA Call setup / initial connection (Cell_DCH)............................................................................ 216H4337HFigure 22: HSDPA Call setup / RAB allocation phase (call establishment done on DCH).................................. 217H4438HFigure 23: Call release (RAB release case)........................................................................................................... 218H4639HFigure 24: RRM new HSDPA subtree ................................................................ .................................................. 219H5140HFigure 25: FDDCell HSDPA Related new objects ................................................................... ............................ 220H5141HFigure 26: HSDPARncConf subtree ....................................................................... .............................................. 221H5342HFigure 27: HSDPA Radio Bearer subtree .................................................................. ........................................... 222H5543HFigure 28: HSDSCHx4SRBDCCH3_4K subtree......................................................................................... ......... 223H5844HFigure 29: HSDPA RLC subtree........................................................................................................................... 224H6045HFigure 30: HSDPA UsHoConf subtree ..................................................................... ............................................ 225H6146HFigure 31: HSDPA BTS new object ...................................................................... ............................................... 226H6447HFigure 32: IuB HSDPA new object....................................................................................................................... 227H6548HFigure 33: Always-on for HSDPA (degraded2AlwaysOn mode) .................................................................... ..... 228H7049HFigure 34: Always-on for HSDPA (releaseOnly mode)........................................................................................ 229H7150HFigure 35: HS-DSCH link is deleted and re-established on new primary (nominal case) .................................... 230H7551HFigure 36: Summary of Inter-freq/inter-RAT mobility......................................................................................... 231H7852HFigure 37: Power allocation at RNC level ................................................................... ......................................... 232H7953HFigure 38: Physical shared channel reconfiguration message............................................................................... 233H8154HFigure 39: Power allocation at NodeB level ................................................................. ........................................ 234H8155H

Figure 40: Transmitted carrier power (on the left) and averaged HSDPA power (on the right)...........................235H

8356HFigure 41: Common measurement .............................................................. .......................................................... 236H8457HFigure 42: Power measurement process................................................................................................................ 237H8558HFigure 43: Power distribution between HS-DSCH and HS-SCCH channels........................................................ 238H8659HFigure 44: measurementPowerOffset transmission......................... ..................................................................... . 239H8760HFigure 45: HS-DSCH power management for 1st transmission............................................................................ 240H8961HFigure 46: Mac-hs transport block adaptation according to the number of Mac-d PDU to transmit .................... 241H9162HFigure 47: HS-DSCH power management for retransmission................................................................. ............. 242H9363HFigure 48: Remaining power for multi-users per TTI scheduling......................................................... ................ 243H9464HFigure 49: HS-SCCH power control overview .................................................................... ................................. 244H9565HFigure 50: discard and backpressure thresholds.................................................................................................... 245H9966HFigure 51: example of traffic regulation with backpressure................................................................................ 246H10167HFigure 52: feature behaviour on Iur ........................................................................ ............................................ 247H10268HFigure 53: example of transport topologies "with ATM priority"....................................................................... 248H10269HFigure 54: example of transport topology "without ATM priority".................................................................... 249H10370HFigure 55: User multiplexing in Code and Time domains .................................................................... .............. 250H108


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71HFigure 56: User throughput vs. HSDPA power, UE cat 6................................................. .................................. 251H10972HFigure 57: HARQ BLER vs. User RLC Throughput, UE cat 12, drive test........ ................................................ 252H11173HFigure 58: User throughput vs. BLER on HS-PDSCH, UE cat 12 ................................................................. .... 253H11274HFigure 59: User throughput vs. status prohibit timer, UE cat 6........................................................................... 254H11575HFigure 60: User throughput vs. polling timer vs. UL BLER............................................................................... 255H11576HFigure 61: User throughput vs. receive window size at UE........ ............................................................... ......... 256H11677HFigure 62: H-BBU resource allocation modes.................................................................. .................................. 257H12078HFigure 63: iCEM consumption for a PS RB DL 128 kbps / UL 384 kbps (R99 Case) ....................................... 258H12179HFigure 64: iCEM consumption for a PS RB HSDPA / UL 128 kbps (HSDPA Case)......................................... 259H12280HFigure 65 : Comparison between the CEM R99 Capacity and the CEM HSDPA Capacity for same input traffic

and same CEM configuration (same hardware) ................................................................. ......................... 260H12281HFigure 66: CEM Capacity vs. HSDPA Penetration.................................................. ........................................... 261H12382HFigure 67: CEM Admission Blocking type (R99 or HSDPA) versus HSDPA Penetration Factor..................... 262H12483HFigure 68: CEM Capacity figures for different configurations depending on the HSDPA penetration factor (UL

64 kbps)....................................................................................................................................................... 263H12484HFigure 69: Admission blocking by service vs HSDPA penetration factor.......................................................... 264H12685HFigure 70: CEM Capacity figures for different configurations depending on the HSDPA penetration factor (UL

128 kbps)..................................................................................................................................................... 265H127


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Parameter Object

Range & Unit

User

Class

Granularity

Value

The protocol messages are written in CAPITAL LETTERS.

The Information Elements (IE) contained in the protocol messages are written the

following way: TPC_DL_Step_Size .

The datafill rules are presented as the following:

Rule:

The system restrictions are presented as the following:

Restriction:

The engineering recommendations on parameter value are presented as the

following:

Engineering Recommendation:

Some parameters values can not be provided in this document; in that case, the

following abbreviations are used:

o N.A.: Not Applicable.

o N.S.: Not Significant.

o O.D.: Operator Dependant (depends on operator network specific

configuration. Example: addressing parameters).


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2 RELATED DOCUMENTS

2.1 REFERENCE DOCUMENTS

[R1] UMT/DCL/DD/0020 UTRAN Parameters User Guide

[R2] 3GPP TS 25.308 UTRA High Speed Downlink Packet Access

(HSPDA); Overall description; Stage 2

[R3] 3GPP TS 34.108 Common Test Environments for User Equipment

(UE) Conformance Testing

[R4] 3GPP TS 25.212 Multiplexing and channel coding (FDD)

[R5] 3GPP TS 25.214 Physical layer procedures (FDD)

[R6] UMT/BTS/DD/012447 NodeB HSDPA functional specification

Commercial release

[R7] UMT/BTS/DD/008196 Mac-hs Scheduler

[R8] UMT/BTS/DD/012545 Variable Length CQI averaging

[R9] UMT/IRC/APP/0164 Iub transport Engineering Guide

[R10] NTP 411-8111-575 HSDPA Feature Activation Procedure

[R11] UMT/SYS/DD/013319 HSDPA System Specification


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3 HSDPA OVERVIEW

3.1 SYSTEM OVERVIEW

3GPP has standardized HSDPA in Release 5 [ 279HR2] in order to increase maximum user

throughput for downlink packet data (streaming, interactive and background traffic

classes) and decrease downlink packet transmission delay. This Release 5 is fully

compatible with the previous Release 99 (R99).

In R99, data are transmitted on a dedicated channel with a given user throughput and

a downlink transmitted power controlled according to the radio conditions:

PowerPower

ControlControl

Data Power

Unused Power Data

Unused

Same Throughput

Figure 1: R99 principle

In HSDPA, data are transmitted on a shared channel by using all the available power

and by controlling the downlink user throughput according to the radio conditions:

RateRate

AdaptationAdaptation 100% Power

100%

Figure 2: HSDPA principle

Typically, a user in good radio conditions will receive his data with a high bit rate

whereas a user in bad radio conditions will receive his data with a lower bit rate.

The efficiency of this rate adaptation is due to a new MAC entity, the Mac-hs layer,

located in the NodeB (see the two following figures), near the physical channel, which

allows a high reactivity in the resource allocation according to the RF conditions


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changes. This Mac-hs layer manages the scheduling of users and the retransmissions

of packets.

HS-DSCH

AssociatedUplink

Signaling

AssociatedDownlink

Signaling

DCCH DTCHDTCHMAC Control MAC ControlCCCH CTCHBCCHPCCHMAC Control

RRC (RNC)RRC (RNC)

RLC (RNC)RLC (RNC)

HS-PDSCH

FACH

S-CCPCH

FACH

S-CCPCH

RACH

PRACH

RACH

PRACH

DSCH

PDSCH

DSCH

PDSCH

DCH

DPCH

CPCH

PCPCH

CPCH

PCPCH

PCH

S-CCPCH

PCHPCH

S-CCPCHHS-DPCCHHS-SCCH

MAC-c/sh

(C-RNC)

MAC-c/sh

(C-RNC)

DCH

DPDCH/DPCCH

R99 L1: Channel Coding / Multiplexing (NodeB)R99 L1: Channel Coding / Multiplexing (NodeB)R5 L1: HSDPA (NodeB)R5 L1: HSDPA (NodeB)

MAC-d

(S-RNC)MAC-hs

(NodeB)

MAC-hs

(NodeB)

Figure 3: HSDPA layer2/layer1 flows

Figure 4: Mac-hs entity on UTRAN side

HSDPA benefits are based on:

New transport and physical channels.


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Fast link adaptation.

Fast retransmission mechanism (HARQ).

Fast scheduling.

3.1.1 NEW TRANSPORT AND PHYSICAL CHANNELS

In R99, downlink data are sent on a DCH (Dedicated CHannel) which is mapped on

the DPDCH (Dedicated Physical Data CHannel). In HSDPA, downlink data are sent

on a HS-DSCH (High Speed Downlink Shared CHannel) which is mapped on one or

several HS-PDSCH (High Speed Physical Downlink Shared CHannel). Users are

multiplexed on the HS-DSCH channel in time and code. Transmission is based on

shorter sub-frames of 2ms (TTI) instead of 10ms in R99.

In downlink, the HS-PDSCH are transmitted with the HS-SCCH (High Speed Shared

Control CHannel) channel. This channel is broadcasted over the cell but his

information concerned only the user who has to receive the HS-PDSCH. The HS-

SCCH allows the user to know if the HS-PDSCH are for him and to decode them

correctly.

Radio conditions information and acknowledgement are reported by the UE to the

NodeB through the HS-DPCCH channel. This channel allows the NodeB to adapt the

downlink data rate and to manage retransmission process. The HS-DPCCH is dividedin two parts. The first one is the Channel Quality Indicator (CQI) which is a value

between 1 and 30 characterizing the radio conditions (1 = bad radio conditions and 30

= good radio conditions). The second one is the acknowledgement information: if data

are well received by the UE, the UE sends to the NodeB an Ack, otherwise a Nack.

HS-DSCH channel is always associated to a DCH. This induces the following

transport channel configuration for any UE established in HSDPA (see the following

figure):

one DCH handling the signaling in both UL and DL,

one DCH transporting the UL traffic,

one HS-DSCH for the DL traffic.


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Figure 5: Transport channel configuration

The following figure summarizes the different channels needed for a HSDPA call:

NodeB

HSDPA UE

HS-PDSCH for data (I/B) trafficHS-PDSCH for data (I/B) traffic

HSDPA channelsHSDPA channels

HS-SCCH signaling part (UE id, ) associated

to HS-PDSCH

HS-SCCH signaling part (UE id, ) associated

to HS-PDSCH

HS-DPCCH Feedback informationHS-DPCCH Feedback information

Associated DPCH for data, speech + SRB trafficAssociated DPCH for data, speech + SRB traffic

Figure 6: HSDPA channels and associated R99 channels

In this release of HSDPA, UE categories 6 and 12 are supported, allowing a maximum

data rate in downlink of respectively 3.65Mbit/s and 1.8Mbit/s. As a consequence the

following radio bearers are be supported:

Interactive or background / UL:8 DL: [max bit rate for UE categories 12 and 6]

/ PS RAB + UL:3.4 DL:3.4 kbps SRBs for DCCH (see below)

Interactive or background / UL:32 DL: [max bit rate for UE categories 12 and

6] / PS RAB + UL:3.4 DL:3.4 kbps SRBs for DCCH





Interactive or background / UL:384 DL: [max bit rate for UE categories 12 and6] / PS RAB + UL:3.4 DL:3.4 kbps SRBs for DCCH


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The maximum bit rate that can be achieved in the UL can be the bottleneck for the

maximum bit rate achievable in the DL. For instance, excessive delay of RLC/TCP

acknowledgements due to low bandwidth in the UL will limit the DL throughput, even if

the RF conditions would allow more.

In UA04.2, Nortel implements the RB adaptation feature that dynamically adapts the

UL bit rate to the amount of traffic carried over the RB. UL adaptation ranges from

32kbps up to 384kbps, but 8kbps is not eligible. Therefore, although UL:8 DL:[max bit

rate for UE categories 12 and 6] will be allocated by the RNC if UL:8 is explicitly

requested in the RAB assignment, it is not recommended to do so, otherwise the user

will experience low throughput in the DL.

3.1.2 FAST LINK ADAPTATION

Every TTI, Adaptive Modulation and Coding (AMC) is updated according to the radio

conditions experienced by the UE and his category (see UE categories section).

AMC (number of codes, code rate and modulation type) is chosen among 30

possibilities corresponding to one CQI in order to reach the maximum bit rate while

guarantying a certain QoS (10% BLER for example). All UE categories have to

support QPSK and 16QAM modulation except categories 11 and 12 which only

support QPSK (16QAM modulation allowing higher bit rate). The following figure

illustrates the AMC by showing the throughput versus the radio conditions (Ior/Ioc):

QPSK

QPSK

QPSK

16QAM

16QAM

-20 -15 -10 -5 0 50

100

200

300

400

500

600

700

800

Ior/Ioc (dB)

Throughput(kbps)

AMC Illustration

QPSK

QPSK

QPSK

16QAM

16QAM

QPSK

QPSK

QPSK

16QAM

16QAM

-20 -15 -10 -5 0 50

100

200

300

400

500

600

700

800

Ior/Ioc (dB)

Throughput(kbps)

AMC Illustration

Figure 7: Example of AMC : Throughput versus Ior/Ioc (radio condition)


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3.1.3 FAST RETRANSMISSION MECHANISM (HARQ)

The HARQ (Hybrid Automatic Repeat Query) is a retransmission mechanism which

consists in:

retransmitting by the NodeB the data blocks not received or received with

errors by the UE;

combining by the UE the transmission and the retransmissions in order to

increase the probability to decode correctly the information.

3.1.3.1 NUMBER OF HARQ PROCESSES

There is an HARQ process assigned per transport block for all the transmissions. The

number of processes per UE is limited and depends on its category. The number of

processes per UE category is the one given in [ 280HR3]:

Ue Category 1 2 3 4 5 6 7 8 9 10 11 12

Number of HARQ Processes 2 2 3 3 6 6 6 6 6 6 3 6

Table 1: Number of processes per UE category

Once this number is reached, the UE should not be eligible by the scheduler for new

transmissions unless one of them is reset (ACK reception, discard timer expiration,max number of retransmissions reached).

3.1.3.2 RV PARAMETERS

The IR (Incremental Redundancy) and modulation parameters necessary for the

channel coding and modulation steps are: the r, s and b values. The r and s

parameters (Redundancy Version or RV parameters) are used in the second rate

matching stage, while the b parameter is used in the constellation rearrangement step

(see [281HR4] for details):

s is used to indicate whether the systematic bits (s=1) or the non-systematic

bits (s=0) are prioritized in transmissions.

r(range 0 to rmax-1) changes the initialization Rate Matching parameter value

in order to modify the puncturing or repetition pattern.

The b parameter can take 4 values (0, , 3) and determines which operations

are produced on the 4 bits of each symbol in 16QAM. This parameter is not

used in QPSK and constitutes the 16QAM constellation rotation for averaging

LLR at the turbo decoder input.


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These three parameters are indicated to the UE by the Xrv value sent on the HS-

SCCH (see section 282H3.3.3 "283HHSDPA Channels & CQI). The coding tables of Xrv are

given hereafter:

Xrv (Value) s r b

0 1 0 0

1 0 0 0

2 1 1 1

3 0 1 1

4 1 0 1

5 1 0 2

6 1 0 3

7 1 1 0

Table 2: RV coding for 16QAM

Xrv (Value) s r

0 1 0

1 0 0

2 1 1

3 0 1

4 1 2

5 0 2

6 1 3

7 0 3

Table 3: RV coding for QPSK

The determination of the s, r and b parameters will be based on the Xrv update, but

not necessarily in the increasing order. The update indeed follows a predefined order

stored in a table (called hereafter Trv). The only requirement to fill this table is that

Trv[0] = 0 for QPSK, or Trv[0] = 0, 4, 5 or 6 for 16QAM (s = 1 and r = 0 must be the

nominal configuration).

A configurable parameter (CC/PIR/MIR) indicates the possibility of switching between

Chase Combining, a Partial IR or a mix between Partial and Full IR sequence. Itimplies that 3 different tables must be stored (see below), chosen accordingly:


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The Chase Combining option corresponds to the first redundancy version

always applied for all (re)transmissions.

The PIR indicates that for all redundancy versions, the systematic bits must

be transmitted (blocks are self-decodable). Only the RV with s = 1 must be

taken into account.

The MIR corresponds to a sequence where both systematic and

nonsystematic bits can be punctured. All possible redundancy versions are

assumed and it corresponds to default Nortels version.

i 1 2 3 4 5 6 7 8

Xrv(QPSK) 0 2 5 6 1 3 4 7

Xrv(16QAM) 6 2 1 5 0 3 4 7

Table 4: RV update table in the MIR case (Trv[i])

i 1 2 3 4 5 6

Xrv(QPSK) 0 2 4 6

Xrv(16QAM) 6 2 5 0 4 7

Table 5: RV update table in the PIR case (Trv[i])

The rules to compute the Xrv parameters then are (see the following figure):

For the first transmission, Xrv is initialized to Trv[0].

Upon reception of a NACK, Xrv is assigned the next value in the table (once

the last value of the table, Nmax, has been set, the next value should be the

first one again).

In case of no reception of ACK/NACK (DTX indication), the parameters must

not be updated so that the same information not received by the UE should be

sent again (this ensure no systematic bits are lost, because all blocks may not

be self-decodable).


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New transmission ?Xrv = Trv[0]

k = 0

Y

N

DTX indication ? Xrv(n) = Xrv(n-1)Y

N

k = k + 1

Xrv(n) = Trv[k mod Nmax]Nmax = 1 (CC)

= 4 (PIR - QPSK)

= 6 (PIR 16QAM)

= 8 (MIR)

Figure 8: RV parameters assignment algorithm

3.1.3.3 STATE OF HARQ PROCESSES

The following figure describes the different states of HARQ processes and possible

actions related to these.


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ACK/NACK/DTX ?

HARQ process assigned

by the scheduler

Y

Update of RV parameters

Data transmission

Wait for ACK/NACK

reception

Insertion of DTX

indication

Reset HARQ processRemove Mac-d PDU

Update structures

Nret = Nret +1

Nret > Nret_max ?

Wait for

retransmission

NACK

DTX

N

WACK state

NACK/DTX state

ACK

Figure 9: ACK/NACK/DTX management for HARQ processes

Once a UE is scheduled, an HARQ process is assigned that may correspond to either

a new Transport Block or a retransmission. The RV parameters are computed

accordingly as described before (see RV PARAMETERS section) and data is

transmitted. The HARQ process is then waiting for feedback information

(ACK/NACK/DTX) and is set in the so-called WACK state (Waiting for

Ack/Nack/DTX). The exact timing for reception of the feedback information must be

computed thanks to the chip offset and relatively to the TTI corresponding to the

transmission.

Upon reception of the feedback information, three behaviors occur:

In case of an ACK, the HARQ process is reset and corresponding Mac-d

PDUs are removed from memory. This HARQ process can now be used for a

new transmission.

In case of a NACK, the number of retransmissions must be incremented. If the

maximum number of retransmissions is not reached, the HARQ process is set

in the so-called NACK state and then inserted in the NACK list of HARQ

processes.

In case of a DTX indication, the same actions as for a NACK reception aredone, except that a parameter must be updated to notify DTX detection (this


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changes the RV parameter update, see RV PARAMETERS section). The

process is then set in the DTX state.

The processes in the NACK or DTX state are just waiting for being re-scheduled for anew retransmission.

3.1.4 FAST SCHEDULING

3.1.4.1 PRINCIPLES

The aim of the Mac-hs scheduler is to optimize the radio resources occupancy

between users. Every TTI, it must then select Queue IDs for which data is going to be

transmitted and the amount of corresponding Mac-d PDUs to transmit.

The scheduler first receives as input every TTI the number of codes available and the

remaining power for HS-PDSCH and HS-SCCH (see POWER MANAGEMENT

section). The received ACK/NACK and CQI must also be provided to the scheduler

when available. Thanks to this information, UE capabilities, configuration parameters

provided by the RNC and taking into account the previously scheduled data, the

scheduler can select the subflows of the users to schedule in order to optimally use

available resources. The main concepts of the scheduler are:

Retransmissions are of higher priority than new transmissions and should be

scheduled first.

Users with higher priority (CmCH-PI) and better CQI are favoured and get

most part of the bandwidth.

The transport blocks should always be optimized according to the transmitted

CQI when possible (if enough codes and power are available and if theres no

CPU limitation).

No queue ID should be left starving, i.e. the scheduler should always allocate

even a small part of radio resources to all users (even those with low priority

and bad CQI).

3.1.4.2 ALGORITHM

The architecture of the scheduler is presented hereafter (see [284HR7] for more details on

the algorithm):


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Figure 10: Scheduler overview

Before entering the scheduler, the Mac-d PDUs for each queue ID of each user are

classified according to their corresponding priority (CmCH-PI). Every TTI, the

scheduler is launched in order to efficiently assign the available resources (number of

codes and remaining power) to the different users.

The first step consists in managing the retransmissions. The NACKed blocks are

scheduled first, in a FIFO order when possible (in case the UE capabilities prevent

from receiving data in the corresponding TTI, it is not retransmitted in that TTI). Then,

once retransmissions are handled, the remaining number of codes and power are

computed and constitute the input of the next step.

The scheduling of first-transmitted data is based on a two-stage solution:

The first stage selects one priority queue among the active ones.

The second stage consists in selecting the user(s) within the chosen priority

queue to schedule.

These two steps are repeated as long as some resources remain (codes, power and

CPU) and if data can be scheduled for the corresponding TTI.

3.1.4.3 FIRST STAGE

The following paragraph describes the general behavior. In this version, as only onepriority queue is available, this first stage is transparent.


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The selection of a priority queue is based on a cost function that takes into account

credits assigned to each priority queue and the number of Mac-d PDUs already

transmitted in the last TTI for these queues. The aim is to provide some throughput

per queue according to its priority: the higher the priority, the higher the allocated

bandwidth.

The credits per queue then depend on their respective priority, on the number of

active priority queues but shall also be proportional to the number of active QIDs per

priority queue (in order to ensure the bandwidth of high priority QIDs remains more

important that low priority ones independently on the number of UEs per priority

queue).

The credits per priority queues are recomputed any time the status of a priority queue

changes (active/inactive) or if the number of active QIDs in a queue changes. When

credits are recomputed, the ratio between queues initially setup is kept.

3.1.4.4 SECOND STAGE

Once a priority queue has been selected, one or more users within that queue are

scheduled. The selection of one QID is done according to another cost function that

takes into account the processed CQI (noted CQIprocessed in CQI section) and the

number of Mac-d PDUs transmitted in the last TTI. This ensures that all users areselected but that the bandwidth allocated to the priority queue is separated between

users according to their CQI (the higher the CQI, the higher the available throughput).

A user can only be considered as candidate if it is allowed to receive some data in the

current TTI, i.e. if several criteria are respected (CQIprocessed 0, min inter TTI distance,

AckNack repetition factor, one HARQ process available, UE not already scheduled for

retransmissions).

For each candidate user, HS-SCCH power is determined (see POWER

MANAGEMENT section) and power checking is done on both the current TTI and the

previous one (HS-SCCH and corresponding HS-PDSCH only overlap by 1 slot). If

there is not enough power to transmit the HS-SCCH in the current TTI, the user is not

selected.

Then for the UE with the lowest cost within the remaining candidates UEs, the number

of PDU to transmit as well as the number of codes and the transmitted power are

chosen according to the processed CQI in order to fit as well as possible to what the

UE can correctly receive (see POWER MANAGEMENT section for more details on

the algorithm):


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If there doesnt remain enough power to transmit the HS-PDSCH, another

configuration requiring less power is selected if possible (transport block size

reduced, corresponding to a smaller CQI referred as CQIapplied in Section 285H6.4

286HPower Management.

If there doesnt remain enough codes to transmit the HS-PDSCH, the

configuration is changed (transport block size reduced, corresponding to a

smaller CQI) to use the remaining codes. The power is then updated

accordingly.

Anytime a UE is scheduled, its cost is recomputed according to the transmitted

number of MAC-d PDUs.

Another priority queue must be selected when no more QID in the current priority

queue can be scheduled (all HARQ processes used for the corresponding UE, min

inter TTI distance not compliant with that TTI, no other QID). As only one priority

queue is available in this version, the first stage is not recalled and the TTI processing

is considered as complete.

The cost of each QID of the selected priority queue is updated anytime another queue

must be selected (according to previous criteria) or at the end of a TTI (no more HS-

SCCH/HS-PDSCH code, power or CPU).


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3.2 DEPLOYEMENT SCENARIOS

3.2.1 DUAL CARRIER

The preferred scenario is to deploy a new layer dedicated to HSDPA on a new

frequency. This layer may be deployed either widely or restricted to some hot-spots.

Layer with HSDPA configured

Layer without HSDPA

Figure 11: HSDPA on dedicated layer

The advantage of this scenario is that there is no impact of HSDPA on the layer that is

already deployed. A Node B can handle HSDPA and non-HSDPA cells at the same

time so there is no need for dedicated NodeB to HSDPA. However if no PA are added

then HSDPA layer will use part of the current power capacity and this will reduce the

coverage of the existing cells. Mobiles are spread over the two layers thanks to the

Traffic Segmentation feature at RRC connection establishment, based on the release

of the mobile and potentially on the traffic class indicated in the establishment cause.

An HSDPA cell is not restricted to HSDPA services: it offers all UA4.2 services (on

Cell_DCH and Cell_FACH) so there is no need to handover to the R99 layer to

establish these services. However mobility between the two layers is managed

through a cell reselection when the mobile is in an HSDPA call. This cell reslection is

not based on quality criteria like in R99. Indeed, mobiles leaving the coverage of the

HSDPA layer will lost his session from a UTRAN point of view but keep his PDP

context from a core network point of view, so that it will perform a cell reselection on

R99 layer.. It is also possible to configure a handover towards 2G (GPRS/EDGE)

when alarm conditions are triggered but it will be a blind handover if the mobile is not

able to perform measurements without compressed mode. For mobiles in Cell_DCH

or Cell_FACH state, mobility is managed as usual even if they are on the HSDPA

layer.


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Another possible scenario is to deploy HSDPA on a separate cluster (managed or not

by a dedicated RNC) but in this case Traffic Segmentation cannot be used as it

assumes a twin-cell topology (see 3.5.1 for more details on Traffic Segmentation).

3.2.2 SINGLE CARRIER

Even though deploying HSDPA on a separate layer is the preferred option, HSDPA

can be configured on any cell and shared his resources with R99. The drawback of

this scenario is that HSDPA traffic may impact R99 traffic by generating high

interferences and may need to re-engineer the layer. If HSDPA is not deployed

everywhere in the layer then an automatic channel type switching between DCH and

HSDPA is performed when the UE enters in or leaves an HSDPA cell.

3.3 HSDPA RESOURCES

3.3.1 OVSF CODES

3.3.1.1 CELL CONFIGURATION

The following figure presents the cell configuration. This configuration provides up to

15 SF16 codes for HS-PDSCH and up to 4 SF128 for HS-SCCH. The common

channels (CPICH, P-CCPCH, S-CCPCH, ) take the equivalent of a SF32. All

remaining OVSF codes can be used for non-HSDPA services (speech, multi-RABs..):

Figure 12: Example of OVSF tree usage with HSDPA


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3.3.1.2 HSDPA CODE ALLOCATION

In the OVSF code tree, all the common channels are allocated in the top of the tree,

as illustrated by the figure below. In Nortel implementation, the HS-PDSCH SF16

codes are allocated and reserved by the RNC at the bottom of the tree. Immediatelyabove, the HS-SCCH SF128 codes are allocated. These codes are allocated at cell

setup and cannot be used or preempted for other services.

SF = nSF = 4SF = 2SF = 1

Cn,n-1

Cn,0

C4,3 = (1,-1,-1,1)

C2,1 = (1,-1)

C4,2 = (1,-1,1,-1)

C1,0 = (1)

C4,1 = (1,1,-1,-1)

C2,0 = (1,1)

C4,0 = (1,1,1,1)

SF = nSF = 4SF = 2SF = 1

Cn,n-1

Cn,0

C4,3 = (1,-1,-1,1)

C2,1 = (1,-1)

C4,2 = (1,-1,1,-1)

C1,0 = (1)

C4,1 = (1,1,-1,-1)

C2,0 = (1,1)

C4,0 = (1,1,1,1) Common channels

n SF128 HS-SCCH

m SF16 HS-PDSCH

Figure 13: OVSF allocation strategy

All the remaining codes are therefore contiguous and left for further DCH allocations.

This includes associated DCH as well as any other calls mapped on DCH (e.g. speech

calls, streaming, etc).

Note that the maximum configuration (15 HS-PDSCH codes and 4 HS-SCCH codes)

is not a valid one as it will leave no room in the OVSF tree for DCH (due to CCH

occupancy) so it would not even be possible to allocate associated SRB for HSDPA

calls.

Note that OCNS code allocation is done before HSDPA configuration and it may lead

to a conflict as HSDPA codes are always allocated from the bottom and need to be

contiguous. In this case the HSDPA configuration will fail. The operator has to modify

OCNS configuration to make it use non-conflicting codes.

3.3.2 POWER

In HSDPA, PA power has to be shared between common channels, DCH channels

and HSDPA channels. In order to manage correctly this new power partition, some

new margins or thresholds are added at RNC and NodeB level:

At RNC level, a minimum power can be reserved for HSDPA.

At NodeB level, a DCH margin allows to take into account the R99 power

fluctuation due to power control.

For more details, see section 287H6.4 288HPower Management.


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3.3.3 HSDPA CHANNELS & CQI

3.3.3.1 PHYSICAL CHANNELS

The following flowchart describes the timing relations between the different physical

channels:

HS-SCCH#2

ACK ACK ACK

7,5 slots

HS-SCCH#1

HS-PDSCH

N_acknack_transmit = 2

2 ms

HS-DPCCH

2 slots

Figure 14: Timing relationship at NodeB between physical channels

The mobile receives a HS-SCCH subframe (see the following figure) containing

control information among which:

Channelization-code-set information (7 bits slot #0 of subframe)

Modulation scheme information (1 bit slot #0 of subframe), i.e.

QPSK/16QAM

Transport-block size information (6 bits slots #1 & #2 of subframe)

Hybrid-ARQ process information (3 bits slots #1 & #2 of subframe)

Redundancy and constellation version (3 bit slots #1 & #2 of subframe)

New data indicator (1 bit slots #1 & #2 of subframe)

UE identity (16 bits used as a mask in slots #0, #1 & #2 of subframe), i.e.

subset of the HRNTI

The SF is fixed to 128. It indicates to which UE data is intended to, on which codes

and with which parameters. There are as many HS-SCCH transmitted during a TTI as

scheduled user number.


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Data

Slot #0 Slot #1 Slot #2

1 HS-SCCH subframe = 2ms

Tslot = 2560 chips = 40 bits

Figure 15: HS-SCCH structure

A mobile decoding its identity in the slot #0 of an HS-SCCH knows that it has been

assigned resources on the HS-PDSCH channels (as indicated, with modulation, in this

slot #0, other information are given in slots #1 and 2): the mobile receives a transportblock on one or several HS-PDSCH (see the following figure).

M= 2 for QPSK

(960 coded bits per TTI)

M = 4 for 16QAM

(1920 coded bits per TTI)

Data

Slot #0 Slot #1 Slot #2

1 HS-PDSCH subframe = 2ms

Tslot = 2560 chips = M*10*2k bits (k = 4, SF16)

Figure 16: HS-PDSCH structure

The HS-PDSCH on which is mapped the HS-DSCH carries only the data payload. The

SF is equal to 16 and up to 15 codes can be reserved to HS-PDSCH per cell. One

HS-DSCH can be mapped onto one or several HS-PDSCH (the maximum number of

codes is given by UE capabilities).

When addressed on HS-SCCH, the UE will then send feedback frame(s) on HS-

DPCCH (SF = 256), roughly 7.5slots after HS-PDSCH frame, containing (see the

following figure):

The HARQ Ack/Nack;

The CQI (Channel Quality Indication).


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CQI

Subframe #0 Subframe #i Subframe #4

1 radio frame = 10ms

Tslot = 2560 chips

= 10 bits

ACK/NACK

2.Tslot = 5120 chips

= 20 bits

Figure 17: HS-DPCCH structure

The HARQ Ack is possibly repeated in consecutive HS-DPCCH subframes using the

N_acknack_transmit parameter, as specified in [ 289HR5] 6A.1.1. The CQI is only sent in

some specific subframes, as specified in [ 290HR5] 6A.1.1, depending on the following

parameters:

The CQI feedback cycle: k,

the repetition factor of CQI: N_cqi_transmit.

For more details on physical channel management, see [291HR6].

3.3.3.2 CQI

The HS-DPCCH channel contains the CQI computed by the mobile from P-CPICH

power measurements. This CQI after demodulation and decoding by the NodeB

(noted CQIreported) is not directly used by the scheduler. As shown by the following

figure, the CQIreported undergoes two processing: a CQI averaging and a CQI

adjustment based on BLER and DTX.


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HS-DPCCH demodulation

and CQI decoding

CQI averaging over several TTI

in order to improve the reliability

of this measurement.

CQI provides to scheduler every TTI

CQI adjustment based on BLER

(to reach a BLER target)

and DTX (in order to deactivate deficient ueby artificially setting its CQI to 0)

CQIreported

CQIaveraged

CQIprocessed

Figure 18: CQI Processing

3.3.3.2.1 CQI AVERAGING

An averaging over several TTI must be done on the CQI values (CQIreported) in order to

improve the reliability of this measurement. The resulting value (CQIaveraged) should

nevertheless be provided to entities needing this information (scheduler, etc) every

TTI (the default CQI feedback cycle is equal to 2 ms). The chosen algorithm consists

in a flexible averaging window which length will be based on CQI correlation

estimation without noise level estimation (see [292HR8] for details).

3.3.3.2.2 CQI ADJUSTMENT

Two algorithms have been introduced to handle bad UE behaviors that would

dramatically disrupt the system. Note that in the nominal case, these algorithmsshould not have any impact.

The purpose of these algorithms is respectively to:

Adjust the received CQI (CQIaveraged) in order to maintain an acceptable BLER

on first transmission.

Isolate a deficient UE which never responds (constant DTX detection).

Both algorithms are processed just after the CQI averaging and can be processed inany order. The resulting CQI from both steps (referred as CQIprocessed in the document)


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constitutes the input of both flow control and scheduler algorithms (except HS-SCCH

power control).

3.3.3.2.3 CQI ADJUSTMENT ACCORDING TO BLER

The first algorithm works on ACK/NACK statistics. The purpose is to correct some bias

on the reported CQI that would lead to excessive BLER. Note that according to the

specifications, the target on the first transmission when applying the reported CQI

would be a 10% BLER. The idea is then to continuously compute the BLER and

modify the reported CQI accordingly in order to reach such target.

It then just consists in computing an offset to apply to the reported CQI (after

averaging), referred in the following as CQI (CQIoutput = CQIaveraged + CQI). In case

the input CQI equals 0, the offset doesnt apply even if positive and the CQI remains

equal to 0. In case CQIoutput becomes inferior or equal to 0, the UE is not scheduled. In

case CQIoutput becomes higher than 30, it is processed as a CQI 30.

It is continuously updated with the following rules:

A buffer of fixed size (= BufferSize) is created for each UE to compute the

BLER.

Anytime an ACK/NACK is received related to the 1st transmission of a

transport block, the buffer is updated to store this information.

o DTX is not taken into account in the buffer.

o The feedback for retransmissions is not either taken into account.

The buffer is filled in a circular manner (i.e. the new value replaces the oldest

one when the buffer is full).

When at least BufferSize stats have been received (the buffer is full), the

number of NACK (NackNb) indication within the last BufferSize ones is

computed. The offset is then updated according to the following rules:

o If NackNb NackNbMin, the system is too good and bandwidth

efficiency could be improved (throughput increase and/or powerreduction). CQI is increased by 1 and the buffer is reinitialized.

o If NackNb > NackNbmax, the BLER is too high. Performances are

then degraded. CQI is decreased by 1 and the buffer is reinitialized.

o In all other cases, the system is considered in its stationary state and

then behaves satisfactorily. CQI is not updated and the buffer is not

reinitialised.

Note that the buffer is only reinitialized when CQI is updated. This allows waiting for

a certain time (BufferSize) before taking a new decision, and thus really evaluating theeffect of the new offset value. If the offset has not been updated, the buffer remains


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filled in a circular manner in order to react as soon as the situation changes (and not

wait for a new period before identifying the problem). The offset is bounded and fits in

the range [-30.. +30].

This is illustrated by the following flowchart.

ACK or NACK received (DTX are

not taken into account

End

Y

Isit the

acknowledgement

of a 1st

transmission ?

Update of statistics buffer

(sliding window like)

StatNb = min(StatNb +1, BufferSize)

N

CQI : offset to apply to averaged CQINackNb : number of Nack in the Stats buffer

StatNb =

BufferSize ?

NackNb

NackNbmin ?

NackNb >

NackNbmax ?CQI = CQI + 1

CQI = CQI - 1No CQI update

Reinit buffer

StatNb = 0

N

N

N

Y

Y

Y

Y

Figure 19: CQI offset computation based on BLER

The default values assumed in a first approach are:

BufferSize = 100

NackNbmin = 0

NackNbmax = 30


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Tests must be done to tune these values. The higher the BufferSize the better the

statistic but the longer the decision. A compromise must then be done between good

precision (BufferSize high and NackNbmax/min close to 10%) and reactivity.

3.3.3.2.4 DEFENSE BASED ON DTX DETECTION

The second algorithm is more a defense mechanism against a deficient UE which

would systematically not detect the HS-SCCH. The purpose is that upon detection of

such UE (based on DTX statistic), it is deactivated by artificially setting its post-

processed CQI to 0. That disables both the scheduler and the flow control algorithm.

The UE would then be released by higher layers as its throughput equals 0.

More in detail, the following steps are processed (see the following figure):

As before, a buffer of fixed size (BufferSize) is created for each UE.

Anytime a feedback information is received, the buffer is updated:

o ACK, NACK and DTX are taken into account.

o Feedback of all transmissions is considered (1st and retransmissions)

as based on the HS-SCCH only.

The buffer is also filled in a circular manner.

As soon as the buffer is full, the evaluation may begin.

If the buffer only contains DTX indications, the UE is considered as deficientand its CQI is set to 0. No recovery is then possible.

If at least one ACK/NACK has been received in the last BufferSize

transmissions, the UE is considered as valid and nothing is done.


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ACK/NACK/DTX received

Permanently set the CQI ofcorresponding UE to 0

(scheduler and flow control disable

N

Only DTX in

the buffer ?

Y

Update of statistics buffer

(sliding window like)StatNb = min(StatNb +1, BufferSize)

StatNb =

BufferSize ?

End

N

Y

Figure 20: Scheduler and Flow Control disabled

Default value:

BufferSize = 100

Note: buffers of both algorithms are independent!

3.4 UE CATEGORIES

3GPP has standardized several UE categories to accommodate a large spectrum of

HSDPA mobile implementations (See [293HR5]). The UE category provides the mobile

capabilities like max number of HS-PDSCH codes supported, modulation schemes

(16QAM, QPSK), MAC-HS transport block size, etc. Each UE category has a tablewith 30 CQI (channel quality indicator) values. Each CQI value provides complete

information regarding the HS-DSCH to be received by UE in DL in the next TTI as

shown below:


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Category 9

Category 10

Category 1-6

Category 11-12

15

...

12

10

...

5

...

5

5

4

...

2

2

2

1

1

1

1

1

1

Number of

HS-PDSCH

16-QAM0.89121602555830

...

16-QAM0.7581601723726

16-QAM0.7567201441125

...

16-QAM0.753360716822

...

16-QAM0.371660356516

QPSK0.691440331915

QPSK0.671120258314

...

QPSK0.483209319*

QPSK0.413207928

QPSK0.341606507*

QPSK0.481604616*

QPSK0.391603775

QPSK0.3303174*

QPSK0.2402333*

QPSK0.1801732*

QPSK0.1401371*

ModulationCode rateThroughput

RLC level

kb/s

Transport Block

SizeCQI value

15

...

12

10

...

5

...

5

5

4

...

2

2

2

1

1

1

1

1

1

Number of

HS-PDSCH

16-QAM0.89121602555830

...

16-QAM0.7581601723726

16-QAM0.7567201441125

...

16-QAM0.753360716822

...

16-QAM0.371660356516

QPSK0.691440331915

QPSK0.671120258314

...

QPSK0.483209319*

QPSK0.413207928

QPSK0.341606507*

QPSK0.481604616*

QPSK0.391603775

QPSK0.3303174*

QPSK0.2402333*

QPSK0.1801732*

QPSK0.1401371*

ModulationCode rateThroughput

RLC level

kb/s

Transport Block

SizeCQI value

Category 7-8

Table 6: UE capabilities

At the high end, UE category 10 can achieve a max RLC throughput = 12 Mbps using

16QAM modulation and 15 OVSF codes SF16 (i.e. entire code tree). At the low end,

UE category 12 achieves a max RLC throughput = 1.4 Mbps with QPSK modulation

and using 5 OVSF codes SF16.

3.5 CALL MANAGEMENT

HSDPA only applies to the PS domain meaning that all the CS domain RABs are

supported on dedicated channels.

The Utran supports only the Traffic Classes Interactive & Background on HSDPA. So,

the TC Streaming is served on DCH.

Moreover, only the mono RB PS I/B are mapped on HSDPA implying that anycombination of RB PS I/B with RB CS call or with any other RB PS I/B (Multi PS) is

served on DCH.


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RB configuration System behavior

All RABs DCH available in HSDPA Cell

Supported: no impact coming from HSDPA. All RAB

combinations existing in this release are available on

DCH in an HSDPA cell (either for a mobile that doesnot support HSDPA or for a RAB combination that is

not supported on HSDPA)

PS I/B on HSDPA Supported on HSDPA

PS Streaming on HSDPA

Speech on DCH + PS I/B on HSDPA

CSD/DCH + PS I/B on HSDPA

(PS I/B+PS I/B) on HSDPA

(PS I/B+PS Streaming) on HSDPA

Speech on DCH + (PS+PS) on HSDPA

Not supported on HSDPA all channels are mapped

on DCH

Table 7: RB Configuration and system behaviour

3.5.1 TRAFFIC SEGMENTATION

In case HSDPA is deployed on one frequency layer on top of the R99 layer, it shall be

possible to re-direct UEs on the proper frequency layer at call setup depending on its

capabilities and requested establishment cause:

an HSDPA capable UE camping on a R99 cell is re-directed to the HSDPA

layer

similarly, a R99 UE camping on a HSDPA cell can be re-directed to the R99

layer.

This feature impacts the choice of the target cell and the frequency layer at the call

establishment.

The main benefits are to allow HSDPA capable mobiles to benefit from HSDPA

service and to avoid loading the HSDPA layer with R99 mobiles.

3.5.1.1 TRAFFIC SEGMENTATION MECHANISM

The redirection is performed by the RNC at the call setup phase based on the twin-

cells configuration which is not compatible in this case with the f1/f2 mobility-capacity

inter-frequency hard hand over.

No redirection is performed by the RNC during the call meaning for example that

even if a mobile, initially on HSDPA layer, reselects the R99 layer in AO cell_fach

state for traffic resuming, it will be served using the DCH layer.

Emergency calls are never redirected and are served on the layer selected by themobile to limit the probability of call setup failure.


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3.5.1.1.1 TRAFFIC SEGMENTATION CRITERIA:

Two filtering can be operated in order to execute the redirection on the suitable layer:

First criterion is based on the Access Stratum Release Indication IE in the

RRC Connection Request message for the identification of the R99/R4

mobiles versus the R5 mobiles

Second optional criterion is based on the Establishment Cause IE in the RRC

Connection Request message to distinguish the calls I/B potentially served on

HSDPA from the others.

This filtering is not necessarily representative of the services setup

during the life of the RRC connection (for example the addition of a

CS call on top of a hsdpa connection implies the switching of the PS

connection on dch channel in the hsdpa layer).

3.5.1.2 TRAFFIC SEGMENTATION PROCEDURE

At the reception of the RRC Connection Request, the RNC identifies:

the UE Release via the Access Stratum Release indicator IE knowing that

R99/R4 mobiles dont support HSDPA configuration

the requested service via the Establishment Cause IE knowing that traffic

class Conversational and Streaming cant be served on HSDPA. This filteringis optional depending on the setting of the parameter

isRedirectionBasedOnEstablishmentCause

So, based on the information of Access Stratum Release indicator and Establishment

Cause IE, the RNC can start the redirection procedure for the R5 mobiles requesting a

PS I/B session.

The redirection consists in indicating the target frequency in the RRC Connection

Setup message via the Frequency Info IE, frequency corresponding to the one of the

twin cell.

The UE will send the RRC Connection Setup Complete towards the twin cell on the

right layer.

Hereafter the static mapping between the Establishment cause sent by the mobile in

the RRC Connection Request and the suitable layer pointed by the RNC :


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Cause Suitable layer Meaning

Originating Conversational Call DCH

Originating Streaming Call DCH

Originating Interactive Call HSDPA

Originating Background Call HSDPA

Originating Subscribed traffic Call HSDPA

Request for access following a request forservice expressed by the mobile user

Terminating Conversational Call DCH

Terminating Streaming Call DCH

Terminating Interactive Call HSDPA

Terminating Background Call HSDPA

Request for access, following a pagingindication received by the mobile.

Emergency CallDCH or HSDPA

(i.e. no re-direction)Speech emergency mobile originated call

Inter-RAT cell re-selectionDCH or HSDPA

(i.e. no re-direction)User location registration following an inter-

system cell reselection

Inter-RAT cell change orderDCH or HSDPA

(i.e. no re-direction)

User location registration following an inter-system cell change commanded by the

source system

Registration HSDPARequest for user registration, following a

mobile power-on

DetachDCH or HSDPA

(i.e. no re-direction)Request for user de-registration, following a

mobile power-off

Originating High PrioritySignalling

HSDPA

Originating Low Priority

Signalling

DCH or HSDPA


Access request for signalling exchange, e.g.SMS,...

Call re-establishment CS caseDCH or HSDPA


Access requested for service re-establishment (due to loss of radio

connection)

Call re-establishment PS caseDCH or HSDPA

(i.e. no re-direction)Routing Area update due to "directed

signalling call re-establishment" RRC release

Terminating High PrioritySignalling

DCH or HSDPA(i.e. no re-direction)

Terminating Low PrioritySignalling

DCH or HSDPA(i.e. no re-direction)

Access request for network initiated signallingexchange, e.g. SMS, ...

Terminating cause unknownDCH or HSDPA

(i.e. no re-direction)This cause is received when no paging cause

is provided from the Core Network.

Table 8: RRC Connection Request and suitable layer


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3.5.1.2.1 PARAMETERS:

isRedirectionForTrafficSegmentation : This parameter is used by the traffic

segmentation feature, in order to redirect mobiles to the adequate layer according to

the UE release indicator.

Parameter isRedirectionForTrafficSegmentation Object InterFreqHhoFddCell

Range & Unit Boolean{True, False}

User Customer

Class 3

Granularity FDDCell

Value

isRedirectionBasedOnEstablishmentCause : This parameter is used by the traffic

segmentation feature in order to take into the establishment cause if the redirection

algorithm.

Parameter isRedirectionBasedOnEstablishmentCause Object InterFreqHhoFddCell

Range & Unit Boolean{True, False}

User Customer

Class 3

Granularity FDDCell

Value

3.5.2 HSDPA CAC

3.5.2.1 RAB MATCHING

Any PS RAB request with Interactive or Background traffic class is matched to the

HSDPA Radio Bearer configuration if the mobile is HSDPA capable and the primary

cell of the active set supports HSDPA. If it is not the case, the request is mapped on

DCH as usual (iRM CAC is performed).

3.5.2.2 ADMISSION PHASE

As today, this mechanism is triggered by the reception of RAB Assignment Request

and follows the RAB matching process.

In this implementation, the specific CAC admission process in the RNC for HSDPA is

based on the number of simultaneous authorized users per cell to limit the

degradation of the quality of service. So, iRM CAC is not played for HSDPA RAB.

Any Interactive/background RAB request is admitted on HSDPA until the maximum

number of simultaneous users allowed on HSDPA is reached for the cell. Unlike the

iRM CAC performed for the RB mapped on DCH channels, the admission on hsdpa

doesnt take into account any other criterion like RF power,


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In case the admission process fails, there is no fallback on DCH. The RAB request will

be rejected.

Once HSDPA CAC has been done, the RNC performs the admission on theassociated DCHs :

Regarding DL SRB admission, CAC is performed as usual

Regarding UL admission, CAC is performed as usual.

3.5.2.2.1 PARAMETER

maximumNumberOfUsers : Used for the HSDPA CAC done by the RNC. The

number of users is per cell

Parameter maximumNumberOfUsers Object HsdpaCellClass

Range & Unit Integer[0..50]

User customer

Class 0

Granularity RNC

Value 20


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3.5.3 CALL SETUP (DATAFLOW)

3.5.3.1 INITIAL CONNECTION PHASE:

There is nothing specific to HSDPA in this phase.

In the scenario of a mobile being redirected due to the traffic segmentation feature, the

target frequency is indicated in the RRC Connection Setup (frequency info IE) but the

call flow is the same.

SGSNNode B RNCUE

RRC/ RACH / RRC connection Request

SCCP/ Connection Request (Initial UE msg (Activate PDP Context Request))

SCCP/ Connection Confirm

RRC/ FACH / RRC Connection Setup (DCCH, U-RNTI,

RRC state = CELL_DCH, [frequency info])

RRC/ RACH / RRC Connection Setup Complete

RRC/ RACH / Initial Direct Transfer (Activate PDP Context Request, PS domain)

The RRC Connection Setup message contains the

signalling bearers (DCCH) definition. A UTRAN

Radio Network Temporary Identity is also

allocated to the UE.

The target RRC state is set to CELL_DCH by the

RNC

If the mobile is redirected for traffic segmentation

reason then frequency info is included

In addition to the initial NAS message, the Initial Direct Transfer message

also contains the CN domain identity, used by the RNC to route the NAS

message to the relevant CN domain (i.e. CS or PS)

The RRC Connection Request message initiated

by the UE contains the establishment cause.

The initial UE message is piggybacked in the

SCCP connection resquest

NBAP/ RL Setup Request)

NBAP / RL Setup

Figure 21: HSDPA Call setup / initial connection (Cell_DCH)


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3.5.3.2 RAB ALLOCATION PHASE:

In this phase, only the NBAP Radio Link Reconfiguration procedure and RRC Radio

Bearer Reconfiguration are modified because of HSDPA.

SGSNNode B RNCUE

SM/Activate PDP Context

GMM/ Authentication and Ciphering

GMM/ Authentication and Ciphering

The UE is authenticated by the SGSN

RANAP/ Security Mode Command

RANAP/ Security Mode

RRC/ Security Mode Command

RRC/ Security Mode Complete

The ciphering and integrity procedures are activa

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