amr sq field trial guidelines

Site Cairo Mobile Networks Division

Originator M. Sobhi H. Ghali

AMR Speech Quality field trial guidelines

Domain : Network Optimization

Division : Methods

Rubric : General

Type : Test specification

Distribution codes : IDDL-PCS, ISC Manager, BR Operation Manager

Pre-distribution:

Abstract: The aim of this document is to present the tests that may be carried out during an Adaptive Multi Rate field trial. For a better understanding, the document starts with a presentation of the feature that will be studied on the field.

Approval

Name

Signature

F. Jarreau N. George F. Colin

Name

Signature

Alcatel File Reference Date Edition Page

AMR_SQ_Field_Trial_Guidelines 3DF019062712QTZZA 3/11/2003 1.0 1

All rights reserved. Passing on and copying of this document, use and communication of its contents not permitted without written authorization.

Table of Contents

1 INTRODUCTION...............................................................................................................................................4

2 AMR FEATURE OVERVIEW..........................................................................................................................5

3 AMR FEATURE DESCRIPTION ....................................................................................................................8

3.1 CODEC MODE ADAPTATION ..................................................................................................................................8

3.2 CHANNEL MODE ADAPTATION ............................................................................................................................11

4 PARAMETERS AND COUNTERS ................................................................................................................17

4.1 PARAMETERS .......................................................................................................................................................17

4.2 PM COUNTERS ....................................................................................................................................................24

5 INTER-OPERABILITY AND LIMITATIONS.............................................................................................26

5.1 HARDWARE COVERAGE.......................................................................................................................................26

5.2 FIRMWARE COVERAGE ........................................................................................................................................27

5.3 LIMITATIONS AND AMR MOBILES .......................................................................................................................27

6 TEST PLAN ......................................................................................................................................................28

6.1 AIM OF THE TEST .................................................................................................................................................28

6.2 TOOLS..................................................................................................................................................................28

A. Available Tools ...................................................................................................................................................28

B. Use of VoiceTool for AMR tests ..........................................................................................................................29

6.3 MEASUREMENTS STRATEGY ................................................................................................................................30

A. Measurements preparation .................................................................................................................................30

B. Post-processing...................................................................................................................................................30

6.4 RESULTS OF PREVIOUS PLATFORM TESTS .............................................................................................................31

6.5 TESTS DESCRIPTION.............................................................................................................................................32

A. AMR-FR [VQAMR001].......................................................................................................................................32

B. AMR-HR [VQAMR002] ......................................................................................................................................32

6.6 MAIN ACTIVITIES AND MANPOWER .....................................................................................................................33




History:

Edition Date Originators Comments

Draft 06-10-03 M.Sobhi , H.Ghali Draft for Cegetel

1.0 29-10-03 M.Sobhi , H.Ghali Released for approval

Edition changes:

References:

[1] 3BK 10204 0479 DTZZA SFD : Adaptive Multi-Rate Speech Codec (AMR)

[2] 3BK 10204 0470 DTZZA SFD : B7 counters improvements

[3] 3BK 11203 0062 DSZZA BSS Telecom Parameter catalogue Release B7

[4] 3DF 01906 2712 VAZZA Voice Quality in Release B7




1 Introduction

This document is dedicated to provide the basic guidelines for the field trials of the GSM B7 feature: Adaptive Multi Rate represented as AMR throughout the document.

This document is organized as follows:

• Part Two is dedicated to the presentation of the mechanism and algorithm of AMR.

• Part Three describes the impact of such feature on the telecom functions.

• Part Four presents the set of parameters and counters impacted with the AMR.

• Part Five presents the inter-operability and limitations in terms of HW, FW or external equipments.

• Part Six presents the test plan that is proposed to be carried out on field.




2 AMR Feature Overview

Adaptive Multi-Rate codec is a new codec defined by ETSI in GSM release 98. This codec provides an enhanced speech quality in all radio conditions and the opportunity to extend the capacity by offering a good Half Rate solution.

AMR is a codec able to adapt the sharing speech information / speech protection to current radio conditions.

AMR is also able to change the channel type (full time-slot to half time-slot), in order to save capacity if radio conditions allow it. Speech information / speech protection adaptation (“codec adaptation”) is made on each speech frame.

This adaptation is illustrated hereafter:

The AMR principle is to have a set of codecs and, for any radio conditions, to use the one with the best speech quality.

Under good radio conditions, a codec with a high bit-rate is used. Speech is encoded with more information so the quality is better. In the channel coding, only little place is left for redundancy.

Under poor radio conditions, a codec with a low bit-rate is chosen. Speech is encoded with less information, but this information can be well protected due to redundancy in the channel coding.

The BSS adapts dynamically the codec in uplink direction and in downlink direction, taking into account the C/I measured by the BTS (for uplink adaptation) and by the MS (for downlink adaptation). The codec used in uplink and used in downlink can be different: the adaptation is independent in each direction. This permits to use an optimal codec for each C/I value of each direction.




The following figure illustrates the concept behind the AMR improvement of the Voice Quality.

C/I [dB]

SpeechQuality[dBQ]

or[MOS]

High bit rate (for example 12.2 kbit/s: EFR)

Medium bit rate (for example 7.95 kbit/s)

Low bit rate (for example 5.90 kbit/s)

AMR-FR with codec subset (12.2, 7.95, 5.90)

List of AMR codecs Codec bit-rate Full

Rate Half Rate

12.2 kbit/s (EFR) X 10.2 kbit/s X 7.95 kbit/s X X (*) 7.40 kbit/s (IS-641)

X X (EFR codec for D-AMPS standard)

6.70 kbit/s X X 5.90 kbit/s X X 5.15 kbit/s X X 4.75 kbit/s X X

(*) : Not supported by the Alcatel BSS.

During a call, a subset of 1 to 4 codecs is used, configured by O&M on a per BSS basis. A different number of codecs and different subsets may be defined for FR (1 to 4 codecs out of the 8 codecs available) and for HR (1 to 4 codecs out of the 5 codecs available).




The AMR feature can be divided in 2 parts:

The channel mode adaptation

The Channel Mode in AMR could be AMR FR or AMR HR.

Two new-defined causes for intracell handover (Causes 26 and 27) ensure the channel mode adaptation for AMR calls. Depending on the quality averages, flags and the type of the channel (Changes must be allowed), an intracell handover is triggered to change an AMR HR into an AMR FR channel or vice versa.

The codec mode adaptation

The codec mode in AMR could be 1 of 8 codecs in AMR FR or 1 of 5 codecs in AMR HR.

During a call, a subset of 1 to 4 AMR codecs is used. They are configured by O&M on a per BSS basis. Depending on the quality of the link, the codec is adapted. A different codec can be used in uplink and downlink. BTS and MS measure the quality of the link and compare it to thresholds given by O&M. A certain hysteresis is built in and is also configured by O&M.

MS

BTS

Codec adaptation

BSC

Channel mode

adaptation

A Short description of impact on the BSC due to codec mode adaptation is given below:

After checking the MS and cell capability for AMR the same AMR-related information must be delivered towards the BTS and the MS to make the codec adaptation possible. This information consists out of:

The subset of codecs for FR/HR configured by O&M on a BSS basis; the threshold values and the hysteresis values to allow codec mode changes

The initial codec or start mode used at the beginning of an AMR call Other than that, the BSC does not interfere in the process of codec mode adaptation. It is the MS (DL) and BTS (UL) who take the codec mode adaptation decision while it is the MS (UL) and TC (DL) who actually perform the adaptation.

A Short description of impact on the BSC due to channel mode adaptation is given below:

For the intra-cell handovers, two new causes will be defined to check the possibility of adapting HR to FR (Cause 26) and FR to HR (Cause 27) for AMR calls. Also, two existing intracell handovers (Cause 15 for UL interference and Cause 16 for DL interference) get specific parameters for AMR calls.




3 AMR Feature Description

3.1 Codec Mode Adaptation

This section describes the codec mode adaptation algorithm.

Inband signaling

MS

BTS

Radiolinkadaptation

Channelcoding &decoding

TC

- Codec Mode Command- Codec Mode Indication

- Codec Mode Request- Codec Mode Indication - Codec Mode Request

- Codec Mode Indication

- Codec Mode Request (1)- Codec Mode Indication

(1) When TFO is not active, Codec Mode Request from the TC to the BTS contains no valid information and is ignored by the BTS.

Codec Mode Indication (uplink and downlink): indicates the codec of the codec subset that has been used to encode the current speech frame and the next speech frame.

Code Mode Command (downlink): after analysis of the uplink radio link, the BTS commands the more optimal codec of the codec subset. The MS shall apply this command for the next uplink speech frame containing Codec Mode Indication.

Codec Mode Request (uplink): after having analyzed the downlink quality of the radio link, the MS requests the more optimal codec of the codec subset. The BTS may apply this request for the next downlink speech frame containing Codec Mode Indication. The BTS may also override the request from the mobile considering possible constraints from network control or BTS hardware. In this case, the BTS keeps unchanged the Codec Mode Indication in the next downlink frame.

Link quality estimation

The quality of the radio link is estimated by evaluating the carrier to interference ratio C/I. The normalized value of the metric is called C/Inorm. The C/I is estimated in the demodulator by comparing the received Training sequence with the expected Training sequence.

When uplink DTX is active,

- the C/Inorm computation is stopped, - it resumes upon reception of a valid frame, by filling in the missing samples with the C/Iest of the received frame.

With uplink DTX active, the MS sends:

- for FR, one SID_UPDATE every 8th frame, - for HR, one SID_UPDATE every 8th frame. This allows the BTS to update the C/Iest regularly.




Threshold comparison

For each pair of adjacent codecs, a threshold and an hysteresis is given by O&M. The figure below shows the case where four codecs are included in the subset.

AMR_THR_3 + AMR_HYST

High

Low

CODEC_MODE_4(less robust)

C/Inorm

AMR_THR_3

CODEC_MODE_3

CODEC_MODE_2

CODEC_MODE_1(most robust)


AMR_THR_2


AMR_THR_1

If only three codecs are present in the subset, then CODEC_MODE_4 is not used and AMR_(FR/HR)_THR_3 is not defined. If only two codecs are present, then CODEC_MODE_3 is also not used and AMR_(FR/HR)_THR_2 is also not defined.

If only one codec is present in the subset, then no threshold is defined because no adaptation is possible. The codec remains fixed. For more details, please refer to the parameters section.




Uplink Codec mode adaptation

The BTS evaluates the C/Inorm and compares it to the thresholds sent by the BSS in the layer 3 message CHANNEL ACTIVATION. If the BTS evaluates that the uplink codec shall be changed, then the BTS sends a Codec Mode Command to the MS in the in-band signaling.

The TC receives a frame with the new codec indicated in Codec Mode Indication field and is able to decode the speech.

Codec Mode Command(new codec mode)

MS BTS TC

C/I evaluation &thresholds comparison

Codec Mode Indication(new codec mode) Codec Mode Indication

(new codec mode)

Downlink Codec Mode Adaptation

The MS evaluates C/Inorm and compares it to the thresholds sent by the BSC to the BTS in the layer 3 messages “Assignment Command” or “Handover Command”. If the MS evaluates that the downlink codec shall be changed, then the MS sends a Codec Mode Request to the BTS in the in-band signaling.

If the BTS agrees to change the downlink codec (no errors in CMI/CMR, the requested codec is present in the codec subset and is adjacent to the current codec), then the BTS forwards immediately the Codec Mode Request to the TC. The TC changes its downlink codec at the next TRAU frame containing a Codec Mode Indication.

Codec Mode Request(new codec mode)

MS BTS TC

C/I evaluation &thresholds comparison

Codec Mode Request(new codec mode)

Codec Mode Indication(new codec mode)

Codec Mode Indication(new codec mode)




3.2 Channel Mode Adaptation

At call setup, if the MS supports AMR HR and the cell is enabled for AMR HR then the AV_LOAD for the cell is calculated and compared with the threshold values THR_FR_LOAD_L_SV3 and THR_FR_LOAD_U_SV3 to determine the variable LOAD_SV3, otherwise the LOAD_SV3 is set to FALSE.

If LOAD_SV3 is found to be TRUE (High Load and AMR HR enabled), then an AMR HR channel is allocated. If LOAD_SV3 is found to be FALSE (Low Load or AMR HR disabled), the an AMR FR channel is allocated.

Two new handover causes are introduced for AMR channel mode adaptation (changing from FR to HR and vice-versa) of AMR calls :

Cause 26: HR to FR channel adaptation due to low radio quality Cause 27: FR to HR channel adaptation due to high radio quality

These two causes are enabled by a single flag: EN_AMR_CA. These two causes of intracell handover belong to a new family called "Channel adaptation HO".

As such,

They are checked after intercell emergency handover causes. While cause 26 (HR-FR) is checked before intracell interference handovers, Cause 27 is checked after them.

That is because while Cause 27 is considered a handover to optimize the resource usage. Cause 26 is considered as considered as urgent in order to save the call from the bad speech quality.

Their trigger is based on radio quality criteria. Cause 26 (HR to FR channel adaptation) must satisfy the intra-cell interference HO level condition.

Order HO family HO cause HO cause reference

1 Emergency HO - Consecutive bad SACCH frames Cause = 7 2 Emergency HO - Level uplink microcell - high threshold Cause = 17 3 Emergency HO - Level downlink microcell - high threshold Cause = 18 4 Emergency HO - Too low quality Uplink Cause = 2 5 Emergency HO - Too low quality Downlink Cause = 4 6 Emergency HO - Too low level Uplink Cause = 3 7 Emergency HO - Too low level Downlink Cause = 5 8 Emergency HO - Too long MS-BS distance Cause = 6 9 Emergency HO - Too short MS-BS distance Cause = 22 10 Emergency HO - Inner zone too low level Uplink Cause = 10 11 Emergency HO - Inner zone too low level Downlink Cause = 11 12 Channel adapt. HO - HR-to-FR channel adaptation due to bad quality Cause = 26 13 Emergency HO - Too high interference intracell Uplink Cause = 15 14 Emergency HO - Too high interference intracell Downlink Cause = 16 15 Better conditions HO - high level in neighbor cell in the preferred band Cause = 21 Better conditions HO - high level in neighbor lower layer cell for slow MS Cause = 14 Better conditions HO - General capture handover Cause = 24 Better conditions HO - Power budget Cause = 12 Better conditions HO - Traffic handover Cause = 23 16 Better conditions HO - Outer zone level Uplink & Downlink Cause = 13 17 Channel adaptation - FR-to-HR channel adaptation due to good quality Cause = 27 18 Better conditions HO - Forced Directed Retry Cause = 20 19 Better conditions HO - Fast traffic handover Cause = 28




There are two ways to trigger Cause 26.

The first way consists in triggering Cause 26 only if a previous intracell handover Cause 15 or 16 has been previously detected in the serving cell for the current MS. This way is intended to non-hopping channels for which an intracell handover Cause 15 or 16 is sometimes sufficient to improve the quality of the call. If the quality is not sufficient after an intracell HO cause 15 or 16 due to a too high interference level, instead of continuing triggering intracell handover Cause 15 or 16, a HR-to-FR channel adaptation is triggered thanks to Cause 26.

The second way applies when the intracell handover Causes 15 and 16 are both disabled for AMR calls (EN_INTRA_DL_AMR = EN_INTRA_UL_AMR = DISABLE). If a too high level of interference is detected in the serving cell for the current MS, Cause 26 is then triggered directly. This second way intends to improve the quality of hopping channels which quality is generally not much improved after an intracell handover Cause 15 or 16. Since AMR is performing well in interference conditions, the thresholds for cause 15 & 16 are replaced especially for AMR (L_RXQUAL_UL/DL_H replaced by L_RXQUAL_UL/DL_H_AMR) , see parameter section.

The Cause 27 channel adaptation handover aims to reduce the number of busy FR TCH when the radio quality is very good and the serving cell becomes loaded. The channel adaptation consists in changing the current full rate TCH (AMR FR) to a half rate TCH (AMR HR).




Detailed trigger of channel adaptation cause 26 / 27

If the following cause is true, then an intra-cell handover from HR to FR is triggered.

CAUSE = 26 (HR-to-FR channel adaptation due to bad radio quality) Current rate is Half Rate (HO-27) AND The current channel is dual rate and changes allowed AND EN_AMR_FR = enable AND { {AV_RXQUAL_UL_CA_HR_FR > THR_RXQUAL_CA+ OFFSET_CA + OFFSET_RXQUAL_FH and AV_RXLEV_UL_HO > RXLEV_UL_IH } OR {AV_RXQUAL_DL_CA_HR_FR > THR_RXQUAL_CA + OFFSET_CA + OFFSET_RXQUAL_FH and AV_RXLEV_DL_HO > RXLEV_DL_IH } } AND EN_AMR_CA = enable AND { (a previous intracell HO Cause 15 or 16 has been raised for this call in the serving cell) OR (EN_INTRA_UL_AMR = disable and EN_INTRA_DL_AMR = disable) }

On A interface, this handover cause is mapped to "Uplink quality".

If the following cause is true, then an intra-cell handover from FR to HR is triggered.

Cause = 27 (FR to HR channel adaptation due to good radio quality) Current channel is Full Rate and EN_AMR_HR = enabled AND Channel type is “dual rate, changes allowed” AND AV_RXQUAL_UL_CA_FR_HR <= THR_RXQUAL_CA + OFFSET_RXQUAL_FH AND AV_RXQUAL_DL_CA_FR_HR <= THR_RXQUAL_CA + OFFSET_RXQUAL_FH AND EN_AMR_CA = enabled

On A interface, this handover cause is mapped to "Better cell”.




AV_RXQUAL_UL_CA_HR_FR and AV_RXQUAL_DL_CA_HR_FR are the averages of, respectively, the uplink and downlink RxQual measured by the MS/BTS, averaged over A_QUAL_CA_HR_FR measurements (Default:8). Similarly, AV_RXQUAL_UL_CA_FR_HR and AV_RXQUAL_DL_CA_FR_HR are the averages of, respectively, the uplink and downlink RxQual measured by the MS/BTS, averaged over A_QUAL_CA_FR_HR measurements (Default:61). Having 2 different averaging window parameters for causes 26 and 27 makes the algorithm more dynamic and makes it possible to facilitate the Quality HO cause 26 while delaying the Better Cell HO cause 27 to avoid a ping pong of channel modes. According to the load of the serving cell, the variables THR_RXQUAL_CA and OFFSET_CA are set as follows: If LOAD_SV3(0) = false

THR_RXQUAL_CA = THR_RXQUAL_CA_NORMAL OFFSET_CA = OFFSET_CA_NORMAL

If LOAD_SV3(0) = true THR_RXQUAL_CA = THR_RXQUAL_CA_HIGH OFFSET_CA = OFFSET_CA_HIGH

The following figure illustrates the Channel Mode Adaptation algorithm.

THR_RXQUAL_CA_NORM

THR_RXQUAL_CA_HIGH

good quality: 0

bad quality: 7

THR_RXQUAL_CA_NORM +OFFSET_CA_NORM

THR_RXQUAL_CA_HIGH +OFFSET_CA_HIGH

Load = FALSE Load = TRUE

HO cause 26

HO cause 27

Full Rate

Half Rate

Quality

HO cause 26

HO cause 27

Full Rate

Half Rate




Interaction with intracell quality handover (causes 15 & 16)

To control the interaction between causes 15/16 and channel adaptation, specific flags are introduced to activate separately causes 15 and 16 for AMR calls.

To take into account AMR specific robustness to interference, specific thresholds are introduced for causes 15 & 16.

CAUSE = 15 (too high interference level on the uplink)

AV_RXQUAL_UL_HO > THR_RXQUAL_CAUSE_15 + OFFSET_RXQUAL_FH and AV_RXLEV_UL_HO > RXLEV_UL_IH and EN_CAUSE_15 = ENABLE and (no previous intracell handover for this connection failed or EN_INTRACELL_REPEATED = ENABLE )


Two sets of parameters are defined to control Cause 15 whether the current call is AMR or not: If the current call is not an AMR call,

EN_CAUSE_15 = EN_INTRA_UL, THR_RXQUAL_CAUSE_15 = L_RXQUAL_UL_H. If the current call is an AMR call,

EN_CAUSE_15 = EN_INTRA_UL_AMR, THR_RXQUAL_CAUSE_15 = L_RXQUAL_UL_H_AMR. CAUSE = 16 (too high interference level on the downlink) AV_RXQUAL_DL_HO > THR_RXQUAL_CAUSE_16 + OFFSET_RXQUAL_FH and AV_RXLEV_DL_HO > RXLEV_DL_IH and EN_CAUSE_16 = ENABLE and (no previous intracell handover for this connection failed or EN_INTRACELL_REPEATED = ENABLE ) Two sets of parameters are defined to control Cause 16 whether the current call is AMR or not: If the current call is not an AMR call,

EN_CAUSE_16 = EN_INTRA_DL, THR_RXQUAL_CAUSE_16 = L_RXQUAL_DL_H. If the current call is an AMR call,

EN_CAUSE_16 = EN_INTRA_DL_AMR, THR_RXQUAL_CAUSE_16 = L_RXQUAL_DL_H_AMR. Note:

EN_CAUSE_15, EN_CAUSE_16, THR_RXQUAL_CAUSE_15 and THR_RXQUAL_CAUSE_16 are HOP internal parameters. They take their values according to whether the call is AMR or not. They are not Omc-R changeable parameters.



Interaction with inter-cell handover

The cause 26 is checked after cause 2 (too low quality on the uplink) and cause 4 (too low quality on the downlink). That means that in case of bad quality and bad level, if an adjacent cell is available then an inter-cell handover will be triggered before any channel mode adaptation.

Interaction with power control

The cause 26 is triggered even if the MS or the BTS does not transmit at maximum power. If the quality decreases, power control may be increasing the transmit power of the MS or the BTS just when the handover cause 26 (HR to FR) is triggered.

The causes 26/27 are triggered independently from the power control algorithm. However, the quality thresholds permit the synchronization between the two algorithms.

Examples of configurations

An operator who wants to have: Under normal load, only AMR FR calls, Under high load, AMR HR calls for qualities 0 to 3, with an hysteresis of 1, will set:

THR_RXQUAL_CA_NORMAL = 0.0 THR_RXQUAL_CA_HIGH = 2.0 OFFSET_CA_NORMAL = 0.0 OFFSET_CA_HIGH = 1.0 An operator who wants to have: Under normal load, AMR HR calls for qualities 0 and 1, with an hysteresis of 1, Under high load, AMR HR calls for qualities 0 to 4, with an hysteresis of 2,

will set: THR_RXQUAL_CA_NORMAL = 0.0 THR_RXQUAL_CA_HIGH = 2.0 OFFSET_CA_NORMAL = 1.0 OFFSET_CA_HIGH = 2.0




4 Parameters and counters

4.1 Parameters

GENERAL AMR PARAMETERS

EN_AMR_FR EN_AMR_HR Instance Cell (Omc-R changeable)

These 2 flags control whether AMR full rate or AMR half rate are allowed in the cell.

Enable Allows AMR full rate/half rate in the cell.

Disable Forbids AMR full rate/half rate in the cell.

Notes To obtain the same behavior as in B6, this parameter should be disabled. For AMR activation, this parameter should be enabled.

EN_INTRA_UL_AMR EN_INTRA_DL_AMR

Instance Cell (Omc-R changeable)

These flags enable / disable the detection of intracell uplink HO (cause 15) and intracell downlink HO (cause 16) respectively for AMR calls. They replace the parameters EN_INTRA_UL and EN_INTRA_DL only for AMR calls.

Enable Enable the detection of intracell UL/DL handover (Causes 15/16).

Disable Disable the detection of intracell UL/DL handover (Causes 15/16).

Notes These parameters are put in place specifically to be able to have different intracell handover strategies for AMR and non AMR calls [E.g. Allow intracell handover causes 15 and 16 for non AMR calls and Disable them for AMR calls].

L_RXQUAL_UL_H_AMR L_RXQUAL_DL_H_AMR


Uplink [Downlink] quality thresholds for handover cause 15 [16]. They are used instead of the parameters L_RXQUAL_UL_H and L_RXQUAL_DL_H only for Handover causes 15 and 16 and strictly for AMR calls. These parameters do not affect the algorithms of quality handover causes 2 and 4.

0 – 7 [Step size 0.1]

Default value: 4.5

Notes These parameters are put in place in order to have the freedom of setting different intracell handover strategies for AMR and non AMR calls.




Downlink_DTX_enable_AMR_FR Downlink_DTX_enable_AMR_HR

Instance BSC (Omc-R changeable)

This flag Enables / disables the use of downlink DTX for AMR FR (or HR respectively) speech calls.

Enable Enables the use of downlink DTX for AMR FR (or HR respectively) speech calls.

Disable Disables the use of downlink DTX for AMR FR (or HR respectively) speech calls.

Notes ___

DTX_INDICATOR_FR_AMR DTX_INDICATOR_HR_AMR


This flag Controls uplink DTX usage for GSM phase 2 MS. Applies only to AMR FR and AMR HR respectively. It replaces the parameter DTX_INDICATOR_FR / DTX_INDICATOR_HR for AMR calls.

0 MAY use DTX 1 SHALL use DTX 2 SHALL NOT use DTX Default value: 2

Notes The following combinations between DTX_INDICATOR_FR / DTX_INDICATOR_HR are possible (FR/HR): may/shall, may/shall not, may/may, shall/shall, shall/shall not, shall/may, shall not/shall and shall not/shall not.

The only combination that is NOT allowed is: DTX_INDICATOR_FR = shall not and DTX_INDICATOR_HR = may, I.e. shall not/may.

FORBID_AMR_NS Instance BSC (Omc-R changeable)

Enable/Disable Noise Suppression in the MS with the AMR codec

Enable The MS can use AMR NS [Default]

Disable The MS can not use AMR NS

Notes ___




CODEC MODE ADAPTATION PARAMETERS

AMR_FR_SUBSET Instance BSS (Omc-R changeable)

Bitmap (8 bits) defining the codec subset that shall be used for AMR FR calls (1 to 4 codecs to be specified from 8 available codecs in AMR FR).

Bit 8 (most significant)=1: 12,2 kbit/s is part of the subset; Bit 7=1: 10.2 kbit/s is part of the subset; Bit 6=1: 7,95 kbit/s is part of the subset; Bit 5=1: 7,40 kbit/s is part of the subset; Bit 4=1: 6,70 kbit/s is part of the subset; Bit 3=1: 5,90 kbit/s is part of the subset; Bit 2=1: 5,15 kbit/s is part of the subset; Bit 1 (least significant)=1: 4,75 kbit/s is part of the subset A minimum of 1 codec and a maximum of 4 codecs must be set mandatory.

Notes The default values of the codec subset should depend on the best speech quality performance viewed under all radio conditions. As viewed in Voice Quality platform tests, the default value is [12.2 kbit/s , 7.95 kbit/s , 5.90 kbit/s]

AMR_HR_SUBSET Instance BSS (Omc-R changeable)

Bitmap (6 bits) defining the codec subset that shall be used for AMR HR calls (1 to 4 codecs to be specified from 5 available codecs in AMR HR).

Bit 8 = Bit 7=0; Bit 6=1: 7,95 kbit/s is part of the subset; [7.95 kbit/s is not supported by Alcatel] Bit 5=1: 7,40 kbit/s is part of the subset; Bit 4=1: 6,70 kbit/s is part of the subset; Bit 3=1: 5,90 kbit/s is part of the subset; Bit 2=1: 5,15 kbit/s is part of the subset; Bit 1 (least significant)=1: 4,75 kbit/s is part of the subset A minimum of 1 codec and a maximum of 4 codecs must be set mandatory.

Notes Mandatory rule: the list should not contain only the 7.40 kbit/s codec mode alone, other codecs should be added in order to have more robust alternatives in case of degraded radio conditions. The default value of the codec subset should depend on the best speech quality performance viewed under all radio conditions.

Default value: [7.40 kbit/s , 5.90 kbit/s , 4.75 kbit/s]




AMR_START_MODE_FR AMR_START_MODE_HR

Instance BSS (Omc-R changeable)

This parameter indicates the codec used at the beginning of a FR (respectively HR) AMR call, until codec mode adaptation is started by the BTS.

0 Implicit rule is used for initial codec mode

1 Lowest codec mode of the subset

2 Second lowest codec mode (used only if the subset contains more than one codec mode)

3 Third lowest codec mode (used only if the subset contains more than two codec modes)

4 Highest codec mode (used only if the subset contains four codec modes)

Notes By lowest codec mode, it is meant the lowest in terms of speech coding bitrate (e.g. the 5.90 kbit/s codec is lower than the 12.2 kbit/s codec) For AMR_START_MODE_HR, 7.40 kbit/s is not permitted as a start codec mode, also 6.7 kbit/s should be avoided as a start codec mode. [3] The implicit rule is defined as follows: If the Active Codec Set contains: 1 mode, then this shall be the Initial Codec Mode; 2 or 3 modes, then the Initial Codec mode shall be the most robust mode of the set (lowest bit rate); 4 modes, then the Initial Codec Mode shall be the second most robust mode of the set (with second lowest bit rate).

AMR_FR_THR_1 AMR_FR_THR_2 AMR_FR_THR_3


Thresholds for AMR FR codec mode adaptation These thresholds are in C/I (the C/I is estimated in the demodulator by comparing the received Training sequence with the expected Training sequence)

0 - 31.5 dB (step size 0.5 dB) Default value: corresponds to the optimal voice quality performance for each codec mode in the FR codec subset. From conducted platform tests, with the default FR codec subset [12.2, 7.95, 5.90 kbit/s] the optimum thresholds were found to be [AMR_FR_THR_2 = 7.5 dB , AMR_FR_THR_1 = 5.5 dB].

Please refer to section 6.4 for more details.

Notes Mandatory rule: AMR_FR_THR_1 <= AMR_FR_THR_2 <= AMR_FR_THR_3 AMR_FR_THR_1 is used between the lowest and the second lowest codec modes (ex: 5.90 and 7.40 kbit/s). It is not used if the number of codec modes in the FR codec subset < 2 AMR_FR_THR_2 is used between the second lowest and the third lowest codec modes (ex: 7.40 and 7.95 kbit/s). It is not used if the number of codec modes in the FR codec subset < 3 AMR_FR_THR_3 is used between the third lowest and the fourth lowest codec modes (ex: 7.95 and 12.2 kbit/s). It is not used if the number of codec modes in the FR codec subset < 4




AMR_HR_THR_1 AMR_HR_THR_2 AMR_HR_THR_3


Thresholds for AMR HR codec mode adaptation These thresholds are in C/I (the C/I is estimated in the demodulator by comparing the received Training sequence with the expected Training sequence)

0 - 31.5 dB (step size 0.5 dB) Default value: corresponds to the optimal voice quality performance for each codec mode in the HR codec subset. The setting of the AMR HR thresholds based on Voice Quality performance requires further tests.

Notes Mandatory rule: AMR_HR_THR_1 <= AMR_HR_THR_2 <= AMR_HR_THR_3 AMR_HR_THR_1 is used between the lowest and the second lowest codec modes (example: 4.75 and 5.15 kbit/s). It is not used if the number of codec modes in the HR codec subset < 2. AMR_HR_THR_2 is used between the second lowest and the third lowest codec modes (example: 5.15 and 5.90 kbit/s). It is not used if the number of codec modes in the HR codec subset < 3. AMR_HR_THR_3 is used between the third lowest and the fourth lowest codec modes (example: 5.90 and 7.40 kbit/s). It is not used if the number of codec modes in the HR codec subset < 4.

AMR_FR_HYST AMR_HR_HYST


Hysteresis for AMR FR/HR codec mode adaptation.

0 – 7.5 dB [step size 0.5 dB] Default value: 2 dB

Notes These hysteresis are only applied when adapting from the lower codec mode (more robust) to the higher codec mode (less robust). [E.g. when adapting the codec mode from 5.15 kbit/s to 5.90 kbit/s the hysteresis is added]. That is to avoid fluctuating back and forth between 2 codecs when the calculated C/I is close to the threshold separating them.




CHANNEL MODE ADAPTATION PARAMETERS

EN_AMR_CA Instance Cell (Omc-R changeable)

This flag Enables/Disables intracell HO for AMR channel adaptation (Handover Causes 26, 27).

Enable Enables intracell HO for AMR channel adaptation. Handover Causes 26, 27 are checked by HOP (HO Preparation process).

Disable Disables intracell HO for AMR channel adaptation. Handover Causes 26, 27 are not checked by HOP.

Notes This parameter can only be enabled if both EN_AMR_FR and EN_AMR_HR are enabled. Handover causes 26 and 27 (AMR HR-AMR FR and AMR FR-AMR HR) are only valid for AMR calls.

A_QUAL_CA_HR_FR A_QUAL_CA_FR_HR


These two parameters are the Quality Averaging window sizes for HR-FR (and FR-HR respectively) channel adaptation. These parameters are used to calculate the AV_RXQUAL_UL/DL_CA in Handover causes 26 and 27.

1 – 61. Unit: SACCH multi frame. Default: A_QUAL_CA_HR_FR = 8 , A_QUAL_CA_FR_HR = 61 according to Ref [3]

Notes Mandatory rule: A_QUAL_CA_FR_HR >= A_QUAL_CA_HR_FR. The averaging window size A_QUAL_CA_HR_FR shouldn’t be greater than the averaging window size for quality handover (A_QUAL_CA_HR_FR > A_QUAL_HO) in order to avoid the inhibition of channel mode adaptation in case of activation of the intra-cell Handovers. The proposed value is to have A_QUAL_CA_HR_FR = A_QUAL_HO The value of 61 (~29 sec) for A_QUAL_CA_FR_HR is a relatively high value and could be optimized during field trials according to the required aggressiveness of usage of HR.

W_QUAL_CA Instance Cell (Omc-R changeable)

Averaging weight applicable for Full Quality for channel adaptation.

1 – 3 Default value: 1

Notes The averaging weighting algorithm works the same as for other weighting factors (E.g. W_LEV_HO , W_QUAL_HO , W_PBGT_HO,…).




THR_RXQUAL_CA_NORMAL THR_RXQUAL_CA_HIGH


Threshold for channel adaptation under normal/High load.

0 – 7 (step size 0.1) Default: 0

Notes Mandatory rule: THR_RXQUAL_CA_HIGH >= THR_RXQUAL_CA_NORMAL THR_RXQUAL_CA_XX is used for FR to HR (Cause 27) adaptation.

While THR_RXQUAL_CA_XX + OFFSET_CA_XX is used for HR to FR (Cause 26) adaptation.

OFFSET_CA_NORMAL OFFSET_CA_HIGH


Offset for channel adaptation hysteresis under normal/high load (cause 26).

0 – 7 (step size 0.1) Default: 4.5

Notes Mandatory rule: OFFSET_CA_HIGH >= OFFSET_CA_NORMAL

THR_FR_LOAD_L_SV3 THR_FR_LOAD_U_SV3


Load thresholds for allocation policy of (Speech Version 3) AMR HR in a dual rate cell supporting AMR HR.

0 – 100%

Default value: Depends on the required degree of HR usage and the number of TRX

Notes Mandatory rules: THR_FR_LOAD_L_SV3 <= THR_FR_LOAD_U_SV3 ,

THR_FR_LOAD_L_SV3 <= THR_FR_LOAD_L_SV1.

The load evaluation algorithm for SV3 works the same way as for the load evaluation algorithm for SV1, only with these different thresholds.




4.2 PM Counters

C701d Measurement Type 1 Traffic Measurements. [Not in Measurement type 110] NB_TCH_AMR_REQ Counter definition: Number of TCH normal assignment requests from AMR mobiles. Trigger condition: Receipt of 08.08 ASSIGNMENT REQUEST from the MSC for speech call with GSM speech coding algorithm version 3 full rate or half rate allowed. History: New in B7 C704a Measurement Type 1 Traffic Measurements. NB_TCH_NOR_AMR_FR_ALLOC Counter definition: Number of TCH normal assignment/mode modify in FR AMR usage - whose channel is allocated in the BSC. Trigger condition: 08.58 CHANNEL ACTIVATION/ MODE MODIFY about to be sent to the BTS, indicating a FR channel with GSM speech coding algorithm version 3, not related to handover. History: New in B7 C704b Measurement Type 1 Traffic Measurements. NB_TCH_NOR_AMR_HR_ALLOC Counter definition: Number of TCH normal assignment/mode modify in HR AMR usage - whose channel is allocated in the BSC. Trigger condition: 08.58 CHANNEL ACTIVATION/ MODE MODIFY about to be sent to the BTS, indicating a HR channel with GSM speech coding algorithm version 3, not related to handover. History: New in B7




MC704 Measurement Type 110 Overview Measurements NB_TCH_NOR_AMR_ALLOC Counter definition: MC704 = C704a + C704b History: New in B7 C447 Measurement type 6. TCH handover measurements NB_TCH_HO_ATPT_26_BadQualHR Counter definition: Number of intracell handover attempts, with the cause 26: "HR to FR channel adaptation due to bad radio quality" on a TCH channel. Trigger condition: Whenever 04.08 ASSIGNMENT COMMAND is sent to the MS via the BTS because of cause 26 on TCH. History: New in B7

C448 Measurement type 6. TCH handover measurements NB_TCH_HO_ATPT_27_GoodQualFR


Counter definition: Number of intracell handover attempts, with the cause 27: "FR to HR channel adaptation due to good radio quality" on a TCH channel. Trigger condition: Whenever 04.08 ASSIGNMENT COMMAND is sent to the MS via the BTS because of cause 27 on TCH. History: New in B7 MC447 Measurement type 110. Overview Measurements NB_TCH_HO_ATPT_QUAL_AMR Counter definition: MC447 = C447 + C448 History: New in B7



5 Inter-operability and limitations

5.1 Hardware Coverage

Supported (Y/N)

BTS Generation: BTS Mk1 N

BTS Mk2 with FUMO N

BTS Mk2 with DRFU Y

BTS G2 with FUMO N

BTS G2 with DRFU Y

Micro-BTS Y

BTS G3 Y

Evolution Y

BSC Generation: BSC G1 N

BSC G2 Y

Evolution Y

Transcoder: TRAU TC16 N

TRAU DT16 Y

TRAU MT120 Y

MSC: MSC E10-R6 Y




5.2 Firmware Coverage

BSS Release: BSS Release B7.2 MR1 onwards

TC Firmware: Only TC with “B7 firmware” (ATxx) e.g. ATI8

NSS Release: (Alcatel) MSC E10-R6 onwards

5.3 Limitations and AMR mobiles

The only limitations on the application of the AMR is:

- That the NSS or core network supports the AMR codec.

- The TC firmware is retrofitted to the B7 platform ATxx

- Unlike TFO, there are no limitations imposed from the other party in the call. [You could have an AMR call while the other party is not using AMR]

AMR requires that the Mobile Station supports the AMR codec. Hence, AMR will only work with AMR supporting mobiles.

Here are some examples on the AMR supporting mobiles in the market:

- Phillips. Fisio 120, 620 and 820 onwards.

- Motorola 720 onwards.

- Alcatel OT 535, 735 onwards

- Siemens SL55 onwards.

- Nokia 1100 and 2300 onwards.

- Sony Ericsson. Up till the P800, AMR is not supported.




6 Test plan

6.1 Aim of the Test

The aim of the tests is to assess the improvement in Voice Quality brought by the introduction of the AMR feature for the end user.

This improvement should especially be assessed in the case of bad radio conditions in order to be able to see the advantage brought by the codec adaptation.

6.2 Tools

This section describes the different tools to be used in order to make the required measurements.

A. Available Tools

Up till present day, there are no commercial tools available capable of measuring the Speech quality for AMR.

1. The PESQ/PSQM Alcatel VoiceTool from Evolium. It calculates the PESQ and PSQM Voice Quality evaluation notes and is mobile independent. It was already configured to work with the Philips AMR mobile. However, measurements performed with this tool should be complemented with any other air interface tool (TEMS, Agilent…) because this tool does not provide GPS information nor any information on the radio conditions (RxLev, RxQual…). Moreover it is a lab tool not really intended for field tests and is really difficult to get out of Evolium.

2. ASCOM QVoice tool. It calculates the PACE notes. However, ASCOM does not have an AMR capable MS configured with the QVoice to date, although it should be introduced in the very near future.

Because the ASCOM QVoice tool is not available yet with AMR mobiles, the Alcatel VoiceTool will be used in the current release of this document. A new release of this document is foreseen with the introduction of the QVoice AMR tool chain.




B. Use of VoiceTool for AMR tests

PC+VoiceTool Software

Audio in Attenuator


Audio out Attenuator Core Network

MS

BSS


Audio in Attenuator


Audio out Attenuator Core Network

MS

BSS

The VoiceTool is composed of a PC installable software and an impedance adaptation device or “attenuator”.

The MS to be used in this case should be an AMR capable MS preferably the Philips MS since it was already used for AMR testing in the platform and validated with the VoiceTool.

The measurements configuration used above is used for DownLink speech quality testing. The DownLink is more interesting to us because we can correlate the DL speech quality with the other DL radio measurements. (RxLev, RxQual, serving cell…).

The VoiceTool does not provide any information about the air interface (RxLev, RxQual, serving cell…). Hence, it should be used in parallel with another air interface tool.

Synchronization between the two tools is essential in order to provide a reliable correlation between the radio conditions and the speech quality. This synchronization will be manually performed by noting the exact time of the launch of the measurements. Since the synchronization accuracy is required only to be within the limit of 1 sec, manual synchronization should be sufficient.

VoiceTool transmits a speech sample between the source and the target PCs. This speech sample is continuously repeated in order to have a continuous assessment of the speech quality.

An example of the VoiceTool text output is shown below.

This output is further processed with Excel macros in order to obtain the statistics required and the correlation with the radio conditions obtained from other tools.




6.3 Measurements Strategy

A. Measurements preparation

− The measurements route should be identified in order to obtain the worst possible radio quality with the least handover rate.

That is in order to be able to assess the benefits brought by AMR, which are especially obvious in bad radio conditions. Intercell handovers should be avoided as much as possibly because we already know their negative effect on the speech quality and this is not the focus of our tests.

− The measurements with/without AMR should be performed in similar traffic conditions, same time of the day and exactly on the same route.

− At least 3000 samples are necessary for each test for reliable statistical distribution. [5-6 hours of measurements]

B. Post-processing

− The synchronized measurements will be treated by Excel macros along with the other radio measurements.

− The final report should include the following:

o Average PESQ/PSQM note and standard deviation.

o Repartition of the PESQ/PSQM notes.

o Other radio measurements (RxQual, RxLev…) and their correlation with the speech quality.

− Below are examples of the output of the Voice Quality evaluation. [Figures below are just examples and not actual values for AMR.]

3

3.1

3.2

3.3

3.4

3.5

3.6

3.7

3.8

PESQ PSQM

Average Speech Quality

EFRAMR




6.4 Results of previous platform tests

Tests were conducted in 2002 in the Evolium platform for AMR validation using the VoiceTool. Below are some of the positive results:

AMR codecs performances

2.22.32.42.52.62.72.82.9

33.13.2

20 8.5 7.5 7 6 5Estimated C/I

PESQ

EFR12.210.27.956.75.94.75

AMR Performance

1.51.71.92.12.32.52.72.93.13.3

20 8.5 7.5 7 6 5

Estimated C/I

PESQ EFR

AMR




6.5 Tests Description

A. AMR-FR [VQAMR001]

Title: Assessment of the VQ gain brought by AMR-FR.

Description: Comparison between AMR-FR and EFR speech quality performances using the VoiceTool.

Preparation: Synchronization of the VoiceTool should be performed at the start of the measurements. Another air interface measurement tool should be used in parallel for radio measurements. AMR should be disabled during the EFR campaign and enabled during the AMR-FR campaign; while HR and AMR-HR should be disabled during both campaigns.

Output:

Comparison of the average PESQ/PSQM values for both campaigns.

Comparison of the PESQ/PSQM histogram.

Comparison of samples with/without handover for the above 2 aspects.

Comparison of the average radio conditions.

Comparison of the map representation of the Good/Bad areas regarding Voice Quality.

B. AMR-HR [VQAMR002]

Title: Assessment of the VQ gain brought by AMR-HR.

Description: Comparison between AMR-HR and HR speech quality performances using the VoiceTool.

Preparation: !!! THIS TEST MAY BE HARD TO PERFORM FOR SOME OPERATORS!!!

A small measurement route should be defined. During the first campaign (HR) all cells should have HR enabled. THR_FR_LOAD_L_SV1 and THR_FR_LOAD_U_SV1 set to 0% hence forcing all mobiles to acquire HR channels! This should be done during the measurements duration only. In the second campaign (AMR-HR), AMR-HR should be enabled with THR_FR_LOAD_L_SV3 and THR_FR_LOAD_U_SV3 set to 0% hence forcing all AMR mobiles to acquire AMR-HR channels.

Output:

Comparison of the average PESQ/PSQM values for both campaigns.

Comparison of the PESQ/PSQM histogram.

Comparison of samples with/without handover for the above 2 aspects.

Comparison of the average radio conditions.

Comparison of the map representation of the Good/Bad areas regarding Voice Quality.




6.6 Main activities and Manpower

The following table gives the manpower, the tools and the duration of each activity performed during the test.

Activity Manpower Tools Duration

1 Measurements preparation and route definition 1 Radio Engineer 1 day

2 Speech Quality measurements EFR/HR without AMR 1 Measurements Technician

VoiceTool+ AMR Mobile+GPS

3 days

3 Speech Quality measurements with AMR-FR/AMR-HR

1 Measurements Technician VoiceTool+

AMR Mobile+GPS 3 days

4 Post processing 1 Radio Engineer Excel macros 2 days

5 Generating a Report 1 Radio Engineer

1 day

N.B For Voice Quality measurements a car, driver and SIM cards are needed.




END OF DOCUMENT




amr sq field trial guidelines

Documents

amr mobiles

amr feature overview

amr feature description

test plan

codec mode adaptation

channel mode adaptation

isc manager

guidelines 3df019062712qtzza