Adaptive Adjustment of HSUPA Small Target Retransmissions(RAN14.0_Draft a)

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Adaptive Adjustment of HSUPA Small TargetRetransmissionsRAN14.0

Feature Parameter Description

Issue Draft A

Date 2012-02-15

HUAWEI TECHNOLOGIES CO., LTD.



Copyright © Huawei Technologies Co., Ltd. 2012. All rights reserved.

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WCDMA RAN

Adaptive Adjustment of HSUPA Small Target

Retransmissions Contents

Issue Draft A (2012-02-15) Huawei Proprietary and Confidential

Copyright © Huawei Technologies Co., Ltd.

i

Contents

1 Introduction ................................................................................................................................ 1-1

1.1 Scope ............................................................................................................................................ 1-1

1.2 Intended Audience ........................................................................................................................ 1-1

1.3 Change History .............................................................................................................................. 1-1

2 Overview ..................................................................................................................................... 2-1

3 Technical Description .............................................................................................................. 3-1

4 Related Features ....................................................................................................................... 4-1

4.1 Required Features ........................................................................................................................ 4-1

4.2 Mutually Exclusive Features ......................................................................................................... 4-1

4.3 Affected Features .......................................................................................................................... 4-1

5 Impact on the Network ............................................................................................................ 5-1

6 Engineering Guidelines ........................................................................................................... 6-1

6.1 When to Use HSUPA Small Target Adaptive Retransmissions ..................................................... 6-1

6.2 Feature Deployment ...................................................................................................................... 6-1

6.3 Performance Monitoring ................................................................................................................ 6-1

7 Parameters ................................................................................................................................. 7-1

8 Counters ...................................................................................................................................... 8-1

9 Glossary ...................................................................................................................................... 9-1

10 Reference Documents ......................................................................................................... 10-1



WCDMA RAN


Retransmissions 1 Introduction



1-1

1 Introduction

1.1 Scope

This document describes the feature Adaptive Adjustment of HSUPA Small Target Retransmissions interms of how the feature works, how to set parameters for it, how it relates to other features, and whatimpact it has on the network. This document also provides engineering guidelines for this feature.

This feature is known as WRFD-140222 Adaptive Adjustment of HSUPA Small Target Retransmissions(Try) in presale activities.

You are advised to read HSUPA Feature Parameter Description before reading this document.

1.2 Intended Audience

This document is intended for:

Personnel who are familiar with WCDMA basics Personnel who need to understand Adaptive Adjustment of HSUPA Small Target Retransmissions

Personnel who work with Huawei WCDMA products

1.3 Change History

This section provides information about the changes in different document versions.

There are two types of changes, which are defined as follows:

Feature change: refers to a change in the feature Adaptive Adjustment of HSUPA Small TargetRetransmissions.

Editorial change: refers to a change in wording or the addition of information that was not described inthe earlier version.

Document Issues

The document issue is as follows:

Draft A (2012-02-15)

Draft A (2012-02-15)

This is the first draft of the document for RAN14.0.

This is a new document.

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WCDMA RAN


Retransmissions 2 Overview



2-1

2 Overview

The hybrid automatic repeat request (HARQ) entity for High Speed Uplink Packet Access (HSUPA) islocated on the NodeB side and used to receive MAC-e protocol data units (PDUs). When a cell cannot

correctly receive MAC-e PDUs from a UE, the HARQ entity requires the UE to retransmit MAC-e PDUs.The average number of retransmissions on the NodeB side needs to converge to a target number ofretransmissions on the RNC side. This target number on the RNC side is dynamically adjusted by thefeature HSUPA Adaptive Retransmission.

With the HSUPA adaptive retransmission feature, a small target number of retransmissions is usedunder normal circumstances. When the uplink load or the UE transmit power is limited, one UE isselected to use a large target number of retransmissions during each period. Without this feature, asmall target number of retransmissions is always used. For details about the HSUPA adaptiveretransmission feature, see HSUPA Feature Parameter Description.

In versions earlier than RAN14.0, the small target number of retransmissions is specified by theEdchTargetLi t t leRetransNum parameter and cannot be adaptively adjusted. When the uplink load is

limited, a small target number of retransmissions will require a high signal-to-interference ratio (SIR) onthe Dedicated Physical Control Channel (DPCCH), and the DPCCH must have a higher power. Thisleads to decreased available power on the Enhanced Dedicated Channel (E-DCH) andEnhanced Dedicated Physical Data Channel (E-DPDCH), a lower UE throughput, and a lower cellthroughput. To address these problems, RAN14.0 introduced the feature Adaptive Adjustment of HSUPASmall Target Retransmissions. This feature supports an alternative small target number ofretransmissions for each typical type of service. The actual small target number of retransmissions candynamically shift between the original fixed number and the alternative number based on the cell uplinkload and UE rates, which are configured by the EdchTargetLitt leRetransNum andEdchAltTarLitt leRetransNum parameters, respectively. This improves the system capacity when theuplink load is limited.

Figure 2-1 shows the relationship between the features HSUPA Adaptive Retransmission and Adaptive

Adjustment of HSUPA Small Target Retransmissions.

Figure 2-1 Relationship between the features HSUPA Adaptive Retransmission and Adaptive Adjustment ofHSUPA Small Target Retransmissions

The features HSUPA Adaptive Retransmission and Adaptive Adjustment of HSUPA Small Target

Retransmissions are independent of each other. With the HSUPA Adaptive Retransmission feature, only




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WCDMA RAN


Retransmissions 2 Overview



2-2

one UE is selected to use the large target number of retransmissions during each period. With the Adaptive Adjustment of HSUPA Small Target Retransmissions feature, when the uplink load is limited,multiple UEs are selected for adjustment to the small target number of retransmissions. This furtherimproves the cell throughput.



WCDMA RAN


Retransmissions 3 Technical Description



3-1

3 Technical Description

Without the feature Adaptive Adjustment of HSUPA Small Target Retransmissions, the RNC setsdifferent target numbers for different typical types of services through the EdchTargetLi t t leRetransNum

parameter. This feature is intended to further improve the cell throughput. An alternative small targetnumber of retransmissions is available for each typical type of service. This alternative small number isconfigured by the EdchAltTarLi t t leRetransNum parameter. The original small number is configured bythe EdchTargetLi t t leRetransNum parameter. The small target number of retransmissions dynamicallyshifts between EdchTargetLitt leRetransNum and EdchAltTarLitt leRetransNum .

Figure 3-1 shows the procedure for dynamically adjusting the small target number of retransmissions.

Figure 3-1 Procedure for dynamically adjusting the small target number of retransmissions

As shown in Figure 3-1, the feature Adaptive Adjustment of HSUPA Small Target Retransmissionsdynamically adjusts the small target number of retransmissions for each single BE service over HSUPA.

When the UE attempts to access the network, the larger value between EdchTargetLitt leRetransNum

and EdchAltTarLitt leRetransNum is used as the small target number of retransmissions if

PC_HSUPA_LITRETNUM_INIT_SEL_SWITCH under the PcSwitch parameter is selected, or




















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WCDMA RAN


Retransmissions 3 Technical Description



3-2

EdchTargetLi t t leRetransNum is used if PC_HSUPA_LITRETNUM_INIT_SEL_SWITCH under thePcSwitch parameter is not selected.

After the UE accesses the network, the following rules apply ifPC_HSUPA_LITRETNUM_AUTO_ADJUST_SWITCH under the PcSwitch parameter is selected:

If the UE rate is above the upper threshold and the uplink load of the cell has not reachedMaxTargetUlLoadFactor multiplied by RelRatioforUlRTWP , the RNC adjusts the small targetnumber of retransmissions to the smaller one between EdchTargetLitt leRetransNum andEdchAltTarLitt leRetransNum in order to raise the UE throughput. The upper threshold equals theminimum bit rate (MBR) of uplink services multiplied by an unconfigurable factor .

If the UE rate is below the lower threshold and the uplink load of the cell has reachedMaxTargetUlLoadFactor multiplied by TrigRatioforUlRTWP , the RNC adjusts the small targetnumber of retransmissions to the larger one between EdchTargetLitt leRetransNum andEdchAltTarLitt leRetransNum in order to raise the cell throughput on the uplink. The lower thresholdequals the MBR of uplink services multiplied by an unconfigurable factor .

In other cases, the RNC does not make any adjustments.

Table 3-1 lists the unconfigurable factors for different MBRs.

Table 3-1 Unconfigurable factors for different MBRs

MBR (Mbit/s)Unconfigurable Factor for theUpper Threshold

Unconfigurable Factor for theLower Threshold

< 1 90% 60%

≥ 1, excluding thefollowing:Services with

Quadrature Phase ShiftKeying (QPSK) modulation

and a 5.44 Mbit/s MBR Services with 16QAM

modulation and an 11.52Mbit/s MBR

90% 70%

5.44 (QPSK modulation) 75% 70%

11.52 (16QAM modulation) 75% 70%

If the features HSUPA Adaptive Retransmission and Adaptive Adjustment of HSUPA Small TargetRetransmissions are both enabled and the air interface resources or UE transmit power on the uplink islimited, the Adaptive Adjustment of HSUPA Small Target Retransmissions feature selects one UE to usethe large target number of retransmissions during each period. If the selected UE later meets theconditions for using the small target number of retransmissions, the larger one betweenEdchTargetLitt leRetransNum and EdchAltTarLitt leRetransNum is used. For details about theseconditions, see the HSUPA Feature Parameter Description.







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WCDMA RAN


Retransmissions 4 Related Features



4-1

4 Related Features

4.1 Required Features

This feature depends on WRFD-010612 HSUPA Introduction Package.

4.2 Mutually Exclusive Features

A cell can be simultaneously configured with the feature Adaptive Adjustment of HSUPA Small TargetRetransmissions and the feature DC-HSUPA. However, if DC-HSUPA is enabled for a UE, Adaptive Adjustment of HSUPA Small Target Retransmissions will not work for this UE.

4.3 Affected Features

None



WCDMA RAN


Retransmissions 5 Impact on the Network



5-1

5 Impact on the Network

Impact on System Capacity

When the uplink load of the cell is limited, the feature Adaptive Adjustment of HSUPA Small TargetRetransmissions increases system capacity.

Impact on Network Performance

None.



WCDMA RAN


Retransmissions 6 Engineering Guidelines



6-1

6 Engineering Guidelines

6.1 When to Use HSUPA Small Target Adaptive

Retransmissions

This feature is recommended if HSUPA is deployed.

6.2 Feature Deployment

For details about how to activate, verify, and deactivate this feature, see Configuring Adaptive Adjustment of HSUPA Small Target Retransmissions.

When configuring the parameter EdchAltTarLi t t leRetransNum , the default value for this parameter isrecommended. An inappropriate value for this parameter may lead to decreased cell throughput. Forservices with a 5.44 Mbit/s MBR and a 2 ms transmission time interval (TTI), this parameter’s defaultvalue is 0.02. For other services with a 2 ms TTI, this parameter’s default value is 0.01. For services with

a 10 ms TTI, this parameter’s default value is 0.1.

6.3 Performance Monitoring

When the uplink load is limited and there are multiple HSUPA UEs, this feature improves the cellthroughput. To verify the effect of this feature, check the value of the counterVS.HSUPA.MeanChThroughput.TotalBytes, which indicates the number of packets received in theHSUPA MAC-d flow in a cell. With the traffic pattern unchanged, this feature is supposed to increase thevalue of this counter.

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WCDMA RAN


Retransmissions 7 Parameters



7-1

7 Parameters

Table 7-1 Parameter description

Parameter ID NE MML Command Description

EdchAltTarLittleRetransNum

BSC6900 ADD UTYPRABOLPC

MOD UTYPRABOLPC

Meaning: Alternative target number of timesthat the MAC-ES flow carrying a service isretransmitted in the small retransmissionstate. This parameter, when used with"EdchTargetLittleRetransNum", increasesthroughput of a single UE or cell throughput.

GUI Value Range: 0~15000

Actual Value Range: 0~15, step: 0.001

Unit: None

Default Value: None

EdchTargetLittleRetransNum

BSC6900 ADD UTYPRABOLPC

MOD UTYPRABOLPC

Meaning: Target number of E-DCH PDUr etransfer when small probabilityretransmission is applied to this service. Thesmall probability retransmission is used toimprove the throughput of a single UE whenthe cell load is in the normal state.


Actual Value Range: 0~15, step: 0.001

Unit: None

Default Value: None

MaxTargetUlLoadFactor

BSC6900 ADD UCELLHSUPA

MOD UCELLHSUPA

Meaning: The parameter specifies the targetvalue of the uplink load. HSUPA powercontrol on the NodeB side keeps uplink loadclose to the target value. For details aboutthis parameter, refer to 3GPP TS 25.433.


Actual Value Range: 0~1

Unit: %

Default Value: 75

RelRatioforUlRTWP BSC6900 ADD UCELLLDM

MOD UCELLLDM

Meaning: UL load restricted releasethreshold ratio.If the state of the load for theTTI switchover algorithm is restricted andthe realtime uplink load factor of cell issmaller than the product of "MaximumTarget Uplink load Factor" and "UL loadrestricted release threshold ratio", then thestate of the load for the TTI switchoveralgorithm is set to normal.



Unit: %




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WCDMA RAN


Retransmissions 7 Parameters



7-2

Parameter ID NE MML Command Description

Default Value: 60

TrigRatioforUlRTWP BSC6900 ADD UCELLLDM

MOD UCELLLDM

Meaning: UL load restricted trigger

threshold ratio.If the state of the load for theTTI switchover algorithm is normal and therealtime uplink load factor of cell is greaterthan the product of "Maximum Target Uplinkload Factor" and "UL load restricted triggerthreshold ratio", then the state of the load forthe TTI switchover algorithm is set torestricted.



Unit: %

Default Value: 73












WCDMA RAN


Retransmissions 8 Counters



8-1

8 Counters

There are no specific counters associated with this feature.



WCDMA RAN


Retransmissions 9 Glossary



9-1

9 Glossary

For the acronyms, abbreviations, terms, and definitions, see the Glossary .

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WCDMA RAN


Retransmissions 10 Reference Documents



10-1

10 Reference Documents

[1] HSUPA Feature Parameter Description


