amr voice quality improvement based on plva(ran15.0_01)

WCDMA RAN

AMR Voice Quality ImprovementBased on PLVA Feature ParameterDescription

Issue 01

Date 2013-04-28

HUAWEI TECHNOLOGIES CO., LTD.

Copyright © Huawei Technologies Co., Ltd. 2013. All rights reserved.

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and other Huawei trademarks are trademarks of Huawei Technologies Co., Ltd.All other trademarks and trade names mentioned in this document are the property of their respective holders. NoticeThe purchased products, services and features are stipulated by the contract made between Huawei and thecustomer. All or part of the products, services and features described in this document may not be within thepurchase scope or the usage scope. Unless otherwise specified in the contract, all statements, information,and recommendations in this document are provided "AS IS" without warranties, guarantees or representationsof any kind, either express or implied.

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Website: http://www.huawei.com

Email: [email protected]

Issue 01 (2013-04-28) Huawei Proprietary and ConfidentialCopyright © Huawei Technologies Co., Ltd.

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mailto:[email protected]

Contents

1 About This Document..................................................................................................................11.1 Scope..............................................................................................................................................................................11.2 Intended Audience..........................................................................................................................................................11.3 Change History...............................................................................................................................................................1

2 Overview.........................................................................................................................................3

3 Technical Description...................................................................................................................43.1 AMR Speech Encoding and Decoding...........................................................................................................................43.2 AMR Speech Decoding Using the Viterbi Algorithm....................................................................................................53.3 AMR Speech Decoding Using the PLVA......................................................................................................................6

4 Related Features.............................................................................................................................8

5 Network Impact.............................................................................................................................9

6 Engineering Guidelines.............................................................................................................106.1 When to Use AMR Voice Quality Improvement Based on PLVA..............................................................................106.2 Planning........................................................................................................................................................................106.2.1 RF Planning...............................................................................................................................................................106.2.2 Network Planning......................................................................................................................................................106.2.3 Hardware Planning....................................................................................................................................................106.3 Deployment..................................................................................................................................................................116.3.1 Requirements.............................................................................................................................................................116.3.2 Activation..................................................................................................................................................................116.3.3 Activation Observation..............................................................................................................................................126.3.4 Deactivation...............................................................................................................................................................126.4 Performance Monitoring...............................................................................................................................................126.5 Parameter Optimization................................................................................................................................................136.6 Troubleshooting............................................................................................................................................................13

7 Parameters.....................................................................................................................................14

8 Counters........................................................................................................................................15

9 Glossary.........................................................................................................................................16

WCDMA RANAMR Voice Quality Improvement Based on PLVA FeatureParameter Description Contents


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10 Reference Documents...............................................................................................................17

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1 About This Document

1.1 ScopeThis document describes WRFD-140201 AMR Voice Quality Improvement Based on PLVA,including its technical principles, related features, network impact, and engineering guidelines.

1.2 Intended AudienceThis document is intended for personnel who:

l Need to understand the features described herein

l Work with Huawei products

1.3 Change HistoryThis section provides information about the changes in different document versions. There aretwo types of changes, which are defined as follows:

l Feature change

Changes in features of a specific product version

l Editorial change

Changes in wording or addition of information that was not described in the earlier version

01 (2013-04-28)

This issue does not include any changes.

Draft A (2013-01-30)

Compared with issue 02 (2012-07-20) for RAN14.0, Draft A (2013-01-30) of RAN15.0 includesthe following changes.

WCDMA RANAMR Voice Quality Improvement Based on PLVA FeatureParameter Description 1 About This Document


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Change Type Change Description Parameter Change

Feature change None None

Editorial change Optimized engineeringguidelines. For details, seechapter 6 EngineeringGuidelines.

None

WCDMA RANAMR Voice Quality Improvement Based on PLVA FeatureParameter Description 1 About This Document


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2 Overview

Adaptive Multi-rate(AMR) audio codec is a patented speech coding scheme adopted by the3GPP as the standard codec for UMTS. Channel encoding for AMR voice services usesconvolutional codes. In RAN14.0, Huawei introduces the Parallel List Viterbi Algorithm(PLVA) to decode convolutional codes. The PLVA outperforms the Viterbi algorithm used bymost vendors and previous Huawei products, and it improves the voice service quality withoutaffecting power control or compromising system capacity. The feature introduces morerobustness to the voice service which is more noticeable in poor radio condition.

AMR Voice Quality Improvement Based on PLVA does not depend on any other feature andcan be used with any other feature.

WCDMA RANAMR Voice Quality Improvement Based on PLVA FeatureParameter Description 2 Overview


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3 Technical Description

3.1 AMR Speech Encoding and DecodingAt the UMTS physical layer, convolutional codes are used to perform channel encoding forAMR voice services and power control is used to ensure AMR voice quality. Figure 3-1 showschannel encoding and power control for UMTS AMR voice services in the uplink.

Figure 3-1 Channel encoding and power control for UMTS AMR voice services in the uplink

As shown in Figure 3-1, the UE uses convolutional codes to encode AMR voice data and sendsthe encoded data to the NodeB. The NodeB decodes the received data and performs a cyclicredundancy check (CRC) on the decoded data. The NodeB then sends the decoded data and aCRC indicator (CRCI) to the RNC. The RNC calculates the block error rate (BLER) for outer-loop power control based on all the CRCIs received. The RNC also sends the decoded data andthe CRCI to the Core Network (CN) for AMR voice data decoding (source decoding).

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NOTE

The RNC calculates the BLER for outer-loop power control based on the ratio of CRCIs indicating CRCfailures to all CRCIs.

AMR voice services include narrowband and wideband AMR voice services. There are threeclasses of narrowband AMR voice services: A, B, and C. There are two classes of widebandAMR voice services: A and B. The Viterbi algorithm and PLVA apply to both narrowband andwideband AMR voice services. The following description is based on narrowband AMR voiceservices. Of the three classes of narrowband AMR voice services, class A is of high importanceand includes a 12-bit number used for CRC. The other classes are of low importance and CRCis not performed on them. 3.1 AMR Speech Encoding and Decoding shows the separatechannel encoding for classes A, B, and C of narrowband AMR services.

Figure 3-2 Channel encoding for classes A, B, and C of narrowband AMR services

3.2 AMR Speech Decoding Using the Viterbi AlgorithmThe Viterbi algorithm is adopted by most vendors to decode convolutional codes. Figure 3-3shows the working mechanism of the Viterbi algorithm.

Figure 3-3 Working mechanism of the Viterbi algorithm

The Viterbi algorithm selects the optimal path based on the maximum likelihood theory andexports the data decoded on the optimal path. If the data decoded on the optimal path fails theCRC, the AMR speech codec discards the data. As a result, voice quality deteriorates.

Figure 3-4 shows the narrowband AMR speech decoding using the Viterbi algorithm.



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Figure 3-4 Narrowband AMR speech decoding using the Viterbi algorithm

As shown in Figure 3-4, the three AMR voice classes are separately decoded by the Viterbidecoder, and the CRC is performed only on the decoded data of class A. The CRCI is used as areference for outer loop power control (OLPC) and is also sent as a bad frame indication (BFI)to the AMR speech codec on the CN. If a BFI indicates that a speech frame is erroneous, theAMR speech codec on the CN discards the speech frame to prevent noise.

3.3 AMR Speech Decoding Using the PLVAHuawei PLVA is an enhanced CRC-assisted Viterbi algorithm. Figure 3-5 shows the workingmechanism of the PLVA.

Figure 3-5 Working mechanism of the PLVA

Instead of selecting only the most optimal path, the PLVA selects the top N optimal paths andperforms CRC on the data decoded on these paths. The PLVA only exports data that passes theCRC. If the data decoded on these paths fails the CRC, the PLVA exports the data decoded onthe optimal path, which is the same path selected by the Viterbi algorithm. The PLVAoutperforms the Viterbi algorithm because it chooses the data decoded on multiple paths, whichinclude the optimal one selected by the Viterbi algorithm. Therefore, when the data decoded bythe Viterbi algorithm is correct, the data decoded by the PLVA is also correct. However, whenthe data decoded by the PLVA is correct, the data decoded by the Viterbi algorithm is notnecessarily correct because there are occasions when the data decoded on the optimal path isincorrect whereas the data decoded on other paths selected by the PLVA is correct. In simulations



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where the PLVA selects four paths, the signal-to-noise ratio (SNR) is 0.2 to 0.8 dB better thanthat produced by the Viterbi algorithm.

Figure 3-6 shows the narrowband AMR speech decoding using the PLVA.

Figure 3-6 Narrowband AMR speech decoding using the PLVA

As shown in Figure 3-6, CRC is performed on the AMR voice data of class A and therefore thedata can be decoded using the PLVA. The mean opinion score (MOS) of class A AMR voicedata is improved by reducing the BLER. CRC is not performed on classes B and C AMR voicedata and therefore classes B and C AMR voice data can only be decoded by using the Viterbialgorithm. The PLVA exports and sends the decoded data, Viterbi CRCI, and PLVA CRCI tothe RNC. The Viterbi CRCI is used for OLPC. The PLVA CRCI serves as the BFI, indicatingwhether a speech frame is erroneous.

The Viterbi CRCI is used for OLPC and the PLVA CRCI serves as the BFI. This dual-CRCImechanism does not affect power control. Note that this feature decreases the uplink BLER andimproves the MOS of AMR voice service by using PLVA, it has no impact on the downlink.



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4 Related Features

Prerequisite FeaturesNone

Mutually Exclusive FeaturesNone

Impacted FeaturesNone

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5 Network Impact

System CapacityNo impact.

Network PerformanceThis feature improves the MOS of AMR voice services, especially the MOS of AMR voiceservices in weak coverage areas.

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6 Engineering Guidelines

6.1 When to Use AMR Voice Quality Improvement Basedon PLVA

This feature can improve the AMR voice quality in the uplink, so it can be applied in any scenariothat meets the deployment requirements. For details about deployment requirements, see section6.3.1 Requirements.

6.2 Planning

6.2.1 RF PlanningRF planning is not required.

6.2.2 Network PlanningNetwork planning is not required.

6.2.3 Hardware PlanningThis feature sets the following requirements on NodeB hardware:

l The BTS3812E, BTS3812A and BTS3812AE must be configured with the EULPd board.

l The DBS3800 must be configured with the EBBCd board.

l The 3900 series base station must be configured with the WBBPd or WBBPf board.

NOTE

Currently, for baseband boards, only the EULPd, EBBCd, WBBPd and WBBPf boards support the PLVAfeature. When the EULPd, EBBCd, WBBPd or WBBPf board is inserted together with other types ofbaseband boards, AMR services cannot obtain the PLVA gain if the AMR services are set up on other typesof baseband boards.

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6.3 Deployment

6.3.1 Requirementsl Operating environment and hardware requirements

– This feature depends on NodeB hardware. For details, see 6.2.3 Hardware Planning.

– The uplink resource group of the cell must contain a baseband board that supports thisfeature. To check whether such a baseband board is contained, perform the followingsteps:

1. For the V200R015 NodeB, run the LST ULOCELL command to check for UL BasebandEquipment ID to obtain the uplink resource group of the cell; for the V100R015 NodeB,run the LST LOCELL command to check for UL BB Resource Group No. to obtain theuplink resource group of the cell.

2. For the V200R015 NodeB, run the LST BASEBANDEQM command to check forBaseband Equipment ID, Cabinet No., Subrack No., and Slot No. to obtain theinformation about the target baseband board; for the V100R015 NodeB, run the LSTULGROUP command to check for UL BB Resource Group No., Cabinet No. of ULProcess Unit, Subrack No. of UL Process Unit, and Slot No. of UL Process Unit toobtain the information about the target baseband board.

3. Verify that the baseband board meets the requirements specified in section 6.2.3 HardwarePlanning.

l Dependencies on other Features

None

l License

The license has been activated. For details about how to activate the license, see LicenseManagement Feature Parameter Description.

Feature ID FeatureName

License Control Item NE Sales Unit

WRFD-140201

AMR VoiceQualityImprovementBased onPLVA

AMR Voice QualityImprovement Based onPLVA (Per Cell)

NodeB Per cell

l Other NEs as well as for network equipment and transmission devices from other vendors

None

6.3.2 ActivationAfter the license is activated, this feature has been activated.



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6.3.3 Activation ObservationThe VS.PLVA.User counter informs operators of the number of UEs using this feature. If thevalue of VS.PLVA.User counter is not 0, this feature is effective.

6.3.4 DeactivationThis feature can be disabled after the license for this feature has been deactivated.

6.4 Performance MonitoringThe gain produced by this feature is reflected by a noticeable increase in the MOS. Take 12.2kbit/s AMR voice services as an example. In the uplink simulations, if the BLER is 1%, theMOS is increased by about 0.08; if the BLER is greater than 10%, the MOS is increased byabout 0.35. (The BLER increase is generally caused by UE power limitation, fast channel change,or strong interference.) In addition, the MOS increase is generally the same under differentchannel fading conditions.

Figure 6-1 describes the MOS comparison for AMR 12.2k voice (Simulation Result in theuplink).

Figure 6-1 MOS comparison for AMR 12.2k voice (simulation result in the uplink)

The MOS gain produced by this feature needs to be tested using the MOS test instrument. End-to-end MOS tests can be performed for this feature. However, this feature provides uplink gains.In this case, the test is recommended only for the uplink MOS.

Fixed-point test in the lab and drive test are available, which are described as follows:

l Fixed-point test in the lab

To conduct a fixed-point test in the lab, perform the following steps:

1. Deactivate this feature and calculate the MOS.

2. Under the same conditions, reactivate this feature and calculate the MOS in the same way.



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The MOS gain is obtained by the average value calculated in step 2 minus that calculated in step1. The MOS gain is about 0.2.

l Drive test

To conduct a drive test in the lab, perform the following steps:

1. Determine a test route, deactivate this feature, and calculate the MOS.2. Under the same conditions, reactivate this feature and calculate the MOS in the same route.

The MOS gain is obtained by the average value calculated in step 2 minus that calculated in step1. The MOS gain is over 0.1.

NOTE

In a drive test, the BLER fluctuates significantly. Therefore, the MOS gain obtained in a drive test isdifferent from that obtained in a fixed-point test in the lab.

6.5 Parameter OptimizationParameter optimization is not required.

6.6 TroubleshootingNone.



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7 Parameters

There are no specific parameters associated with this feature.

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8 Counters

Table 8-1 Counter description

Counter ID Counter Name CounterDescription

NE Feature ID Feature Name

50332258 VS.PLVA.User Numbers of plvauser in one cell

NodeB Multi-mode:NoneGSM: NoneUMTS:WRFD-140201LTE: None

AMR VoiceQualityImprovementBased on PLVA

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9 Glossary

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

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10 Reference Documents

1. 3GPP TS 25.101, "User Equipment (UE) radio transmission and reception (FDD)"2. 3GPP TS 25.212, "Channel Coding and Multiplexing"3. 3GPP TS 26.090, "AMR Speech Codec; Speech transcoding," December 20094. License Management Feature Parameter Description

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amr voice quality improvement based on plva(ran15.0_01)

Documents

huawei trademarks

huawei proprietary

huawei industrial basebantian

amr speech decoding

amr speech encoding

thepurchase scope

usage scope

related features