SIST ETS 300 581-4 E1:2003

European digital cellular telecommunications system; Half rate speech; Part 4: Comfort noise aspects for the half rate speech traffic channels (GSM 06.22)

..

Evropski digitalni celični telekomunikacijski sistem – Govor s polovično hitrostjo – 4. del: Vidiki znosnega šuma v prometnih kanalih z govorom s polovično hitrostjo (GSM 06.22)

General Information

• Status: Published
• Publication Date: 30-Nov-2003
• ICS: 33.070.50 - Global System for Mobile Communication (GSM)
• Technical Committee: SS EIT - Technical Board for the electrotechnical, information technology and telecommunications fields
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 01-Dec-2003
• Due Date: 01-Dec-2003
• Completion Date: 01-Dec-2003
• Mandate: T-172
• Ref Project: ETSI ETS 300 581-4 ed.1 (1995-12) - European digital cellular telecommunications system; Half rate speech; Part 4: Comfort noise aspects for the half rate speech traffic channels (GSM 06.22)

Standards Content (Sample)

SLOVENSKI STANDARD
SIST ETS 300 581-4 E1:2003
01-december-2003
(YURSVNLGLJLWDOQLFHOLþQLWHOHNRPXQLNDFLMVNLVLVWHP±*RYRUVSRORYLþQRKLWURVWMR±
GHO9LGLNL]QRVQHJDãXPDYSURPHWQLKNDQDOLK]JRYRURPVSRORYLþQRKLWURVWMR
*60
European digital cellular telecommunications system; Half rate speech; Part 4: Comfort
noise aspects for the half rate speech traffic channels (GSM 06.22)
Ta slovenski standard je istoveten z: ETS 300 581-4 Edition 1
ICS:
33.070.50 Globalni sistem za mobilno Global System for Mobile
telekomunikacijo (GSM) Communication (GSM)
SIST ETS 300 581-4 E1:2003 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST ETS 300 581-4 E1:2003

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SIST ETS 300 581-4 E1:2003
EUROPEAN ETS 300 581-4
TELECOMMUNICATION November 1995
STANDARD
Source: ETSI TC-SMG Reference: DE/SMG-020622
ICS: 33.060.50
European digital cellular telecommunications system, Global System for Mobile communications
Key words:
(GSM)
European digital cellular telecommunications system;
Half rate speech
Part 4: Comfort noise aspects for the half rate
speech traffic channels
(GSM 06.22)
ETSI
European Telecommunications Standards Institute
ETSI Secretariat
F-06921 Sophia Antipolis CEDEX - FRANCE
Postal address:
650 Route des Lucioles - Sophia Antipolis - Valbonne - FRANCE
Office address:
c=fr, a=atlas, p=etsi, s=secretariat - [e-mail]
X.400: Internet:
Tel.: [phone] - Fax: [phone]
*
Copyright Notification: No part may be reproduced except as authorized by written permission. The copyright and the
foregoing restriction extend to reproduction in all media.
© European Telecommunications Standards Institute 1995. All rights reserved.

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ETS 300 581-4: November 1995 (GSM 06.22 version 4.1.1)
Whilst every care has been taken in the preparation and publication of this document, errors in content,
typographical or otherwise, may occur. If you have comments concerning its accuracy, please write to
"ETSI Editing and Committee Support Dept." at the address shown on the title page.

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ETS 300 581-4: November 1995 (GSM 06.22 version 4.1.1)
Contents
Foreword .5
1 Scope .7
2 Normative references.7
3 Definitions, symbols and abbreviations.7
3.1 Definitions .7
3.2 Symbols .8
4 General.9
5 Functions on the transmit (TX) side .9
5.1 Background acoustic noise evaluation .9
5.2 Modification of the speech encoding algorithm during SID frame generation .11
5.3 SID-frame encoding.12
6 Functions on the receive (RX) side .12
6.1 Averaging of the GS parameters .12
6.2 Comfort noise generation and updating.13
7 Computational details.14
History.15

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ETS 300 581-4: November 1995 (GSM 06.22 version 4.1.1)
Foreword
This European Telecommunication Standard (ETS) has been produced by the Special Mobile Group
(SMG) Technical Committee of the European Telecommunications Standards Institute (ETSI).
This ETS specifies the half rate speech traffic channels for the European digital cellular
telecommunications system. This ETS corresponds to GSM technical specification, GSM 06.22, version
4.1.1 and is part 4 of a multi-part ETS covering the half rate speech traffic channels as described below:
GSM 06.02 ETS 300 581-1: "European digital cellular telecommunications system;
Half rate speech Part 1: Half rate speech processing functions".
GSM 06.20 ETS 300 581-2: "European digital cellular telecommunications system;
Half rate speech Part 2: Half rate speech transcoding".
GSM 06.21 ETS 300 581-3: "European digital cellular telecommunications system;
Half rate speech Part 3: Substitution and muting of lost frames for half rate
speech traffic channels".
GSM 06.22 ETS 300 581-4: "European digital cellular telecommunications system;
Half rate speech Part 4: Comfort noise aspects for half rate speech traffic
channels".
GSM 06.41 ETS 300 581-5: "European digital cellular telecommunications system;
Half rate speech Part 5: Discontinuous Transmission (DTX) for half rate speech
traffic channels".
GSM 06.42 ETS 300 581-6: "European digital cellular telecommunications system;
Half rate speech Part 6: Voice Activity Detection (VAD) for half rate speech
traffic channels".
GSM 06.06 ETS 300 581-7: "European digital cellular telecommunications system;
Half rate speech Part 7: ANSI-C code for the GSM half rate speech codec".
GSM 06.07 ETS 300 581-8: "European digital cellular telecommunications system;
Half rate speech Part 8: Test vectors for the GSM half rate speech codec".
NOTE: TC-SMG has produced documents which give the technical specifications for the
implementation of the European digital cellular telecommunications system.
Historically, these documents have been identified as GSM Technical Specifications
(GSM-TS). These TSs may have subsequently become Interim European
Telecommunication Standards (I-ETSs), (Phase 1), or European Telecommunication
Standards (ETSs), (Phase 2), whilst others may become ETSI Technical Reports
(ETRs).
Transposition dates
Date of adoption of this ETS: 27 October 1995
Date of latest announcement of this ETS (doa): 28 February 1996
Date of latest publication of new National Standard
or endorsement of this ETS (dop/e): 31 August 1996
Date of withdrawal of any conflicting National Standard (dow): 31 August 1996

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ETS 300 581-4: November 1995 (GSM 06.22 version 4.1.1)
1 Scope
This European Telecommunication Standard (ETS) gives the detailed requirements for the correct operation
of the background acoustic noise evaluation, noise parameter encoding/decoding and comfort noise
generation in GSM Mobile Stations (MS)s and Base Station Systems (BSS)s during Discontinuous
Transmission (DTX) on half rate speech traffic channels.
The requirements described in this ETS are mandatory for implementation in all GSM MSs capable of
supporting the half rate speech traffic channel.
The receiver requirements are mandatory for implementation in all GSM BSSs capable of supporting the
half rate speech traffic channel, the transmitter requirements are only for those where downlink DTX will
be used.
2 Normative references
This ETS incorporates by dated and undated reference, provisions from other publications. These
normative references are cited at the appropriate places in the text and the publications are listed
hereafter. For dated references, subsequent amendments to or revisions of any of these publications
apply to this ETS only when incorporated in it by amendment or revision. For undated references, the
latest edition of the publication referred to applies.
[1] GSM 01.04 (ETR 100): "European digital cellular telecommunication system
(Phase 2); Abbreviations and acronyms".
[2] GSM 06.20 (ETS 300 581-2): "European digital cellular telecommunications
system; Half rate speech Part 2: Half rate speech transcoding".
[3] GSM 06.41 (ETS 300 581-5): "European digital cellular telecommunications
system; Half rate speech Part 5: Discontinuous transmission (DTX) for half rate
speech traffic channels".
[4] GSM 06.42 (ETS 300 581-6): "European digital cellular telecommunications
system; Half rate speech Part 6: Voice Activity Detector (VAD) for half rate
speech traffic channels".
[5] GSM 06.06 (ETS 300 581-7): "European digital cellular telecommunications
system; Half rate speech Part 7: ANSI-C code for the GSM half rate speech
codec".
3 Definitions, symbols and abbreviations
3.1 Definitions
For the purpose of this ETS, the following definition apply.
frame: Time interval of 20 ms corresponding to the time segmentation of the half rate speech transcoder,
also used as a short term for a traffic frame.
SID frame: Rame characterised by the SID (Silence Descriptor) codeword. It conveys information on the
acoustic background noise.
SID codeword: Fixed bit pattern for labelling a traffic frame as a SID frame.
SID field: The bit positions of the SID codeword within a SID frame.
speech frame: Traffic frame that cannot be classified as a SID frame.
VAD flag: Voice Activity Detector flag.
SP flag: SPeech flag.

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ETS 300 581-4: November 1995 (GSM 06.22 version 4.1.1)
W(Z): Spectral weighting filter of the GSM half rate speech codec.
H(Z): Combination of the short term (spectral) filter A(z) and the spectral weighting filter W(z).
Other definition of terms used in this ETS can be found in GSM 06.20 (ETS 300 581-2) [2] and
GSM 06.41 (ETS 300 581-5) [3]. The overall operation of DTX is described in
GSM 06.41 (ETS 300 581- 5) [3].
3.2 Symbols
For the purpose of this ETS, the following symbols apply.
GS Energy tweak parameter.
R0 Frame energy value.
R(i) Unquantised (normalised) autocorrelation sequence.
r Optimal reflection coefficient.
j
  b
SUM ( x(n) ) = x(a) + x(a+1) + . + x(b-1) + x(b);  (Accumulation)
n=a
GSP0 codeword Vector quantization index, joint vector quantization of the parameters GS and
P0.
P0 Power contribution of the first excitation vector as a fraction of the total
excitation power at a subframe.
3.3 Abbreviations
For the purpose of this ETS, the following abbreviations apply:
AFLAT Autocorrelation Fixed Point LAttice Technique (used in the GSM half rate
speech codec for the vector quantization of the LPC coefficients)
BSS Base Station System
DTX Discontinuous Transmission
ETS European Telecommunication Standard
GSM Global System for Mobile communications
MS Mobile Station
SID SIlence Descriptor
RX Receive
TX Transmit
VAD Voice Activity Detector
VQ Vector Quantization
For abbreviations not given in this subclause, see GSM 01.04 (ETR 100) [1].

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4 General
A problem when using DTX is that the background acoustic noise, which is transmitted together with the
speech, would disappear when the radio transmission is switched off, resulting in a modulation of the
background noise. Since the DTX switching can take place rapidly, it has been found that this effect may be
annoying for the listener, especially in a car environment with high background noise levels. In bad cases,
the speech may be hardly intelligible.
This ETS specifies a solution to overcome this problem by generating s
...