WB AMR(GBSS14.0_01)

WB AMR GBSS14.0

Feature Parameter Description

Issue 01

Date 2012-04-28

HUAWEI TECHNOLOGIES CO., LTD.

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

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GSM BSS

WB AMR Contents

Issue 01 (2012-04-28) Huawei Proprietary and Confidential

Copyright Huawei Technologies Co.,

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Contents

1 Introduction to This Document ............................................................................................. 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

3.1 WB AMR Encoding and Decoding ................................................................................................ 3-1

3.2 Speech Rate Adjustment ............................................................................................................... 3-1

3.3 Rate Adjustment Threshold Adaptation ......................................................................................... 3-1

3.4 Power Control ................................................................................................................................ 3-2

3.5 TFO ............................................................................................................................................... 3-2

3.6 WB AMR in A over IP Mode .......................................................................................................... 3-2

3.7 Impact on KPIs .............................................................................................................................. 3-3

4 Engineering Guidelines ........................................................................................................... 4-1

5 Parameters.................................................................................................................................. 5-1

6 Counters ...................................................................................................................................... 6-1

7 Glossary ...................................................................................................................................... 7-1

8 Reference Documents ............................................................................................................. 8-1

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WB AMR 1 Introduction to This Document



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1 Introduction to This Document

1.1 Scope

This document describes the WB AMR feature. It describes Wide Band Adaptive Multi Rate Codec (WB AMR) speech encoding/decoding, rate adjustment threshold adaptation, WB AMR power control, enabling Tandem Free Operation (TFO) and Discontinuous Transmission (DTX) in the case of WB AMR. (GBFD-115507 WB AMR)

1.2 Intended Audience

Users of this document are assumed to be familiar with GSM basics and have a working knowledge of GSM telecommunication.

This document is intended for:

Personnel working on Huawei GSM products or systems

System operators who need a general understanding of this feature

1.3 Change History

This section provides information on 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 WB AMR feature of a specific product version.

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

Document Issues

The document issues are as follows:

01 (2012-04-28)

Draft A (2012-02-15)

01 (2012-04-28)

This is the first release of GBSS14.0.

Compared with issue draft A (2012-02-15) of GBSS14.0, issue 01 (2012-04-28) of GBSS14.0 has no change.

Draft A (2012-02-15)

This is a draft.

Compared with issue 01 (2011-03-31) of GBSS13.0, Draft A (2012-02-15) of GBSS14.0 incorporates the changes described in the following table.

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WB AMR 1 Introduction to This Document



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Change Type

Change Description Parameter Change

Feature change

Deleted the description for DTX. Deleted the following parameters:

FRDLDTX

FRULDTX

HRDLDTX

HRULDTX

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WB AMR 2 Overview



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2 Overview

The sampling frequency of the traditional narrowband speech signals is 8 kHz, and the speech frequency ranges from 200 Hz to 3400 Hz. With the development of communication technologies, users have higher requirements for speech quality. The narrowband speech signals, however, cannot always meet users' requirements for speech quality. WB AMR is introduced to provide high-grade speech quality.

The sampling frequency of WB AMR is 16 kHz, and the speech frequency ranges from 50 Hz to 7 kHz. Compared with AMR, WB AMR has wide high frequency extension and low frequency extension. Therefore, WB AMR can provide better speech quality.

In the GSM system, WB AMR specifies five speech encoding rates. In addition, WB AMR occupies only full-rate channels.

Currently, Huawei WB AMR supports only one Active Codec Set (ACS). The ACS contains three speech encoding rates: 6.60 kbit/s, 8.85 kbit/s, and 12.65 kbit/s. The BSC automatically selects an appropriate speech encoding rate from the ACS.

Table 2-1 lists the speech encoding rates supported by WB AMR.

Table 2-1 WB AMR speech encoding rates

Encoding Rate WB AMR

6.60 kbit/s

8.85 kbit/s

12.65 kbit/s

15.85 kbit/s -

23.85 kbit/s -

NOTE

-: not supported

: supported

WB AMR corresponds to full-rate speech version 5. That is, WB AMR is enabled only when VOICEVER is set to FULL_RATE_VER5. To enable WB AMR, the MSC must support full-rate speech version 5.

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WB AMR 3 Technical Description



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3 Technical Description

3.1 WB AMR Encoding and Decoding

Encoding

The sampling frequency of the Pulse Code Modulation (PCM) code stream on the A interface is 8 kHz, whereas the sampling frequency of WB AMR is 16 kHz. WB AMR takes samples of the speech data before encoding it. In addition, WB AMR raises the sampling frequency of the PCM code stream that is decompressed according to the A-law or -law to 16 kHz before encoding it.

Decoding

After decoding, the sampling frequency of the PCM code stream is 16 kHz. The standard sampling frequency of the PCM code stream on the A interface, however, is 8 kHz. Therefore, the sampling frequency of the decoded PCM code stream needs to be decreased and compressed according to A-law or -law before being sent over the A interface.

3.2 Speech Rate Adjustment

WB AMR speech rate adjustment refers to the process in which the AMR codec mode of a call on a channel frequently changes to adapt to the variations of the interference level in the radio environment.

Each WB AMR codec mode has an adjustment threshold, which is used to select the codec mode that best suits the C/I ratio of the interference level in the radio environment. The hysteresis is introduced to avoid the constant changes of the codec mode. The value of the threshold ranges from 0 to 63. Value 1 indicates 0.5 dB, and value 2 indicates 1 dB. The rest may be deduced by analogy. The value of the hysteresis ranges from 0 to 15. The hysteresis value complements the threshold.

INITCDMDWB specifies the initial WB AMR codec mode used for a call.

The speech rate adjustment policy of WB AMR is the same as the speech rate adjustment policy of AMR. For details, see AMR Feature Parameter Description.

The parameters related to WB AMR speech rate adjustment are listed as follows:

ULTHWB1

ULHYSTWB1

DLHYSTWB1

DLTHWB1

ULTHWB2

ULHYSTWB2

DLHYSTWB2

DLTHWB2

3.3 Rate Adjustment Threshold Adaptation

The WB AMR rate adjustment threshold adaptation function enables the BSC to monitor the speech quality in real time and to adaptively modify the threshold parameters. Therefore, an appropriate WB AMR codec mode can always be selected for the call. For details, see AMR Feature Parameter Description.

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3.4 Power Control

The procedure of power control for WB AMR calls is similar to the procedure of power control for AMR calls. For details, see AMR Feature Parameter Description.

3.5 TFO

Due to the high sampling frequency, WB AMR can provide more spectrum information on speech signals. The spectrum information, however, is partially lost on the A interface due to the decrease of the sampling frequency to 8 kHz. This affects the quality of services provided by WB AMR.

In A over TDM mode, the transcoder (TC) forcibly initiates TFO negotiation after a WB AMR call is set up, If both the calling and called MSs support TFO, TFO can be performed.

The TFO Message is transmitted in fixed bit spacing on the A interface. Specifically, the TFO Message is used to replace the least significant bit in the first byte of every 16 PCM bytes. In this way, the impact on speech quality is reduced to a negligible level. Messages that are transmitted in fixed bit spacing can only be transmitted on a 16 kbit/s subchannel. The TFO Frame and TFO Message are transmitted without encoding or decoding. When the TFO Frame and TFO Message are transmitted over the A interface, the sampling frequency need not be decreased. In this way, the spectrum information on speech signals can be saved and the speech quality can be ensured. Figure 3-1 shows the working mechanism of TFO.

Figure 3-1 Working mechanism of TFO

BSC

(TC)BTS MSC

BSC

(TC)BTS

Endcoding DecodingSpeech compression

PCM

PC

M

Speech

frameSpeech

frame

TFO TFODisable

Tandem

operation

Disable

Tandem

operation

Disable

Tandem

operation

Disable

Tandem

operation

The frame format used on the A interface is described as follows: The first six high bits carry the PCM frame, and the last two low bits carry the TFO Frame and TFO Message.

After TFO is performed, the TC combines the 48 kbit/s PCM frame compressed according to A-law or -law with 16 kbit/s TFO Frame and TFO Message. The TC then sends the combined frame over the A interface to the MSC.

In the downlink, the TC extracts the TFO Frame and TFO Message from the last two low bits, converts the TFO Frame and TFO Message to the TRAU frame, and sends the TRAU frame. The transmission of the TRAU frame does not involve decoding.

For details on TFO negotiation, see TFO Feature Parameter Description.

3.6 WB AMR in A over IP Mode

In A over IP mode, the BSC does not perform encoding or decoding, and the Media Gateway (MGW) performs the functions of the TC. In this case, the BSS performs encoding and decoding only on channels.

To enable WB AMR in A over IP mode that requires the support from the MSC or MGW, the CN must support Transcoder Free Operation (TrFO).

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3.7 Impact on KPIs

The encoding and decoding of WB AMR calls require a large number of resources. Therefore, when WB AMR is enabled, the number of speech paths supported by the BSC is reduced in A over TDM mode. In addition, like AMR, WB AMR also has an impact on the call drop rate, congestion rate, handover-related KPIs, and traffic volume. For details, see impact on KPIs in AMR Feature Parameter Description.

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WB AMR 4 Engineering Guidelines



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4 Engineering Guidelines

WB AMR cannot be used together with Voice Quality Enhancement (VQE) or Enhanced Packet Loss Concealment (EPLC).

The WB AMR feature requires support from MSs. Therefore, you are advised to enable the WB AMR feature in areas that have high penetration for WB AMR-capable MSs.

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WB AMR 5 Parameters



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5 Parameters

Table 5-1 Parameter description

Parameter ID

NE MML Command Description

INITCDMDWB

BSC6900 SET GCELLCCAMR

Meaning: Initial coding mode used for broadband AMR calls. The three values 0, 1 and 2 of this parameter respectively represent the lowest, low and highest coding rates in the ACS. This parameter does not take effect in A over IP mode. In A over IP mode, the TC is integrated into the UMG. The BSC6900 obtains the initial coding mode based on 3GPP TS 45.009 instead of parameter configuration.

GUI Value Range: 0~2

Actual Value Range: 0~2

Default Value: 2

Unit: None

VOICEVER

BSC6900 SET GCELLCCACCESS

Meaning: Speech version supported by a cell.

GUI Value Range: FULL_RATE_VER1(Full-rate VER 1), FULL_RATE_VER2(Full-rate VER 2), FULL_RATE_VER3(Full-rate VER 3), HALF_RATE_VER1(Half-rate VER 1), HALF_RATE_VER2(Half-rate VER 2), HALF_RATE_VER3(Half-rate VER 3), FULL_RATE_VER5(Full-rate VER 5)

Actual Value Range: FULL_RATE_VER1, FULL_RATE_VER2, FULL_RATE_VER3, HALF_RATE_VER1, HALF_RATE_VER2, HALF_RATE_VER3, FULL_RATE_VER5

Default Value: FULL_RATE_VER1-1&FULL_RATE_VER2-0&FULL_RATE_VER3-0&HALF_RATE_VER1-1&HALF_RATE_VER2-0&HALF_RATE_VER3-0&FULL_RATE_VER5-0

Unit: None

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WB AMR 6 Counters



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6 Counters

Table 6-1 Counter description

Counter ID

Counter Name Counter Description Feature ID

1282411447

CELL.INTRACEL.HO.REQ.TIMES.WBAMR.WB.NWB

H3006A:Internal Intra-Cell Handover Requests (WBAMR) (WB-NWB)

GBFD-115507

1282411448

CELL.INTRACEL.HO.REQ.TIMES.WBAMR.NWB.WB

H3006B:Internal Intra-Cell Handover Requests (WBAMR) (NWB-WB)

GBFD-115507

1282411449

CELL.INTRACELL.HO.CMD.TIMES.WBAMR.WB.NWB

H3016A:Internal Intra-Cell Handover Commands (WBAMR) (WB-NWB)

GBFD-115507

1282411450

CELL.INTRACELL.HO.CMD.TIMES.WBAMR.NWB.WB

H3016B:Internal Intra-Cell Handover Commands (WBAMR) (NWB-WB)

GBFD-115507

1282411451

CELL.INTRACELL.HO.FAIL.TIMES.WBAMR.WB.NWB

H3026A:Failed Internal Intra-Cell Handovers (WBAMR) (WB-NWB)

GBFD-115507

1282411452

CELL.INTRACELL.HO.FAIL.TIMES.WBAMR.NWB.WB

H3026B:Failed Internal Intra-Cell Handovers (WBAMR) (NWB-WB)

GBFD-115507

1282411478

CALL.CELL.DROP.WBAMR.CALL.FAIL.TIMES

M0121C:WBAMR Service Channel Call Drop Times

GBFD-115507

1282411479

CELL.CALL.SPEECH.VER.5.REQ.TIMES.TCHF

A0402D:Request Times Of Full Rate Speech Version 5

GBFD-115507

1282411481

CELL.CALL.OCCUPY.SUCC.TIMES.TCHF.WBAMR

A0409Q:WBAMR TCH Successful Call Occupancy Times (Service Channel)

GBFD-115507

1282411508

CELL.ASS.CMP.TIMES.SPEECH.VER.5.NOT.INCLUDE.DR.TCHF

A3113:Speech Version 5 Completed Assignments (Excluding Directed Retry) (TCHF)

GBFD-115507

1282411509

CELL.ASS.CMP.TIMES.SPEECH.VER.5.DIRECT.RETRY.DR.TCHF

A3114:Cell Assignment Complete Times of Speech Version 5 (Direct Retry) (TCHF)

GBFD-115507

1282423798

CELL.INTRACELL.HO.SUCC.RATE.WBAMR.WB.TO.NWB

TH3036A:Success Rate of Internal Intra-Cell Handover (WBAMR) (WB-NWB)

GBFD-115507

1282423799

CELL.INTRACELL.HO.SUCC.RATE.WBAMR.NWB.TO.WB

TH3036B:Success Rate of Internal Intra-Cell Handover

GBFD-115507

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Counter ID

Counter Name Counter Description Feature ID

(WBAMR) (NWB-WB)

1282423817

CELL.CHAN.BUSY.NUM.TCHF.WBAMR.TRAF.AVE

AR3556C:Traffic Volume on WBAMR TCHFs

GBFD-115507

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WB AMR 7 Glossary



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7 Glossary

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

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WB AMR 8 Reference Documents



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8 Reference Documents

[1] 3GPP TS 28.062 "Inband Tandem Free Operation (TFO) of speech codecs; Service description; Stage 3"

[2] 3GPP TS 48.060 "In-band control of remote transcoders and rate adaptors for full rate traffic channels"

[3] BSC6900 Feature List

[4] BSC6900 Optional Feature Description

[5] BSC6900 GSM Parameter Reference

[6] BSC6900 GSM MML Command Reference

[7] BSC6900 GSM Performance Counter Reference

[8] AMR Feature Parameter Description

[9] TFO Feature Parameter Description

[10] Discontinuous Transmission and Discontinuous Reception Feature Parameter Description

1 Introduction to This Document1.1 Scope1.2 Intended Audience1.3 Change HistoryDocument Issues01 (2012-04-28)Draft A (2012-02-15)

2 OverviewTable 2-1 WB AMR speech encoding rates

3 Technical Description3.1 WB AMR Encoding and DecodingEncodingDecoding

3.2 Speech Rate Adjustment3.3 Rate Adjustment Threshold Adaptation3.4 Power Control3.5 TFOFigure 3-1 Working mechanism of TFO

3.6 WB AMR in A over IP Mode3.7 Impact on KPIs

4 Engineering Guidelines5 ParametersTable 5-1 Parameter description

6 CountersTable 6-1 Counter description

7 Glossary8 Reference Documents[1] 3GPP TS 28.062 "Inband Tandem Free Operation (TFO) of speech codecs; Service description; Stage 3"[2] 3GPP TS 48.060 "In-band control of remote transcoders and rate adaptors for full rate traffic channels"[3] BSC6900 Feature List[4] BSC6900 Optional Feature Description[5] BSC6900 GSM Parameter Reference[6] BSC6900 GSM MML Command Reference[7] BSC6900 GSM Performance Counter Reference[8] AMR Feature Parameter Description[9] TFO Feature Parameter Description[10] Discontinuous Transmission and Discontinuous Reception Feature Parameter Description

WB AMR(GBSS14.0_01)

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