1、 ETSI TS 146 022 V14.0.0 (2017-04) Digital cellular telecommunications system (Phase 2+) (GSM); Half rate speech; Comfort noise aspects for the half rate speech traffic channels (3GPP TS 46.022 version 14.0.0 Release 14) TECHNICAL SPECIFICATION GLOBAL SYSTEM FOR MOBILE COMMUNICATIONSRETSI ETSI TS 14
2、6 022 V14.0.0 (2017-04)13GPP TS 46.022 version 14.0.0 Release 14Reference RTS/TSGS-0446022ve00 Keywords GSM ETSI 650 Route des Lucioles F-06921 Sophia Antipolis Cedex - FRANCE Tel.: +33 4 92 94 42 00 Fax: +33 4 93 65 47 16 Siret N 348 623 562 00017 - NAF 742 C Association but non lucratif enregistre
3、 la Sous-Prfecture de Grasse (06) N 7803/88 Important notice The present document can be downloaded from: http:/www.etsi.org/standards-search The present document may be made available in electronic versions and/or in print. The content of any electronic and/or print versions of the present document
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9、I ETSI TS 146 022 V14.0.0 (2017-04)23GPP TS 46.022 version 14.0.0 Release 14Intellectual Property Rights IPRs essential or potentially essential to the present document may have been declared to ETSI. The information pertaining to these essential IPRs, if any, is publicly available for ETSI members
10、and non-members, and can be found in ETSI SR 000 314: “Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in respect of ETSI standards“, which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web server (https:/ipr.etsi.org
11、/). Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web server) which are, or may be, or may become, essential to the pre
12、sent document. Foreword This Technical Specification (TS) has been produced by ETSI 3rd Generation Partnership Project (3GPP). The present document may refer to technical specifications or reports using their 3GPP identities, UMTS identities or GSM identities. These should be interpreted as being re
13、ferences to the corresponding ETSI deliverables. The cross reference between GSM, UMTS, 3GPP and ETSI identities can be found under http:/webapp.etsi.org/key/queryform.asp. Modal verbs terminology In the present document “shall“, “shall not“, “should“, “should not“, “may“, “need not“, “will“, “will
14、not“, “can“ and “cannot“ are to be interpreted as described in clause 3.2 of the ETSI Drafting Rules (Verbal forms for the expression of provisions). “must“ and “must not“ are NOT allowed in ETSI deliverables except when used in direct citation. ETSI ETSI TS 146 022 V14.0.0 (2017-04)33GPP TS 46.022
15、version 14.0.0 Release 14Contents Intellectual Property Rights 2g3Foreword . 2g3Modal verbs terminology 2g3Foreword . 4g31 Scope 5g32 References 5g33 Definitions, symbols and abbreviations . 5g33.1 Definitions 5g33.2 Symbols 6g33.3 Abbreviations . 6g34 General . 6g35 Functions on the transmit (TX) s
16、ide . 7g35.1 Background acoustic noise evaluation . 7g35.2 Modification of the speech encoding algorithm during SID frame generation 8g35.3 SID-frame encoding . 9g36 Functions on the receive (RX) side 10g36.1 Averaging of the GS parameters 10g36.2 Comfort noise generation and updating 11g37 Computat
17、ional details . 11g3Annex A (informative): Change Request History 12g3History 13g3ETSI ETSI TS 146 022 V14.0.0 (2017-04)43GPP TS 46.022 version 14.0.0 Release 14Foreword This Technical Specification has been produced by the 3rdGeneration Partnership Project (3GPP). The present document gives the det
18、ailed requirements for the correct operation of the background acoustic noise evaluation, noise parameter encoding/decoding and comfort noise generation within the digital cellular telecommunications system. The present document is part of a series covering the half rate speech traffic channels as d
19、escribed below: GSM 06.02 “Digital cellular telecommunications system (Phase 2+); Half rate speech; Half rate speech processing functions“. GSM 06.06 “Digital cellular telecommunications system (Phase 2+); Half rate speech; ANSI-C code for the GSM half rate speech codec“. GSM 06.07 “Digital cellular
20、 telecommunications system (Phase 2+); Half rate speech; Test sequences for the GSM half rate speech codec“. GSM 06.20 “Digital cellular telecommunications system (Phase 2+); Half rate speech; Half rate speech transcoding“. GSM 06.21 “Digital cellular telecommunications system (Phase 2+); Half rate
21、speech; Substitution and muting of lost frames for half rate speech traffic channels“. GSM 06.22 “Digital cellular telecommunications system (Phase 2+); Half rate speech; Comfort noise aspects for half rate speech traffic channels“. GSM 06.41 “Digital cellular telecommunications system (Phase 2+); H
22、alf rate speech; Discontinuous Transmission (DTX) for half rate speech traffic channels“. GSM 06.42 “Digital cellular telecommunications system (Phase 2+); Half rate speech; Voice Activity Detector (VAD) for half rate speech traffic channels“. The contents of the present document are subject to cont
23、inuing work within the TSG and may change following formal TSG approval. Should the TSG modify the contents of the present document, it will be re-released by the TSG with an identifying change of release date and an increase in version number as follows: Version x.y.z where: x the first digit: 1 pr
24、esented to TSG for information; 2 presented to TSG for approval; 3 or greater indicates TSG approved document under change control. y the second digit is incremented for all changes of substance, i.e. technical enhancements, corrections, updates, etc. z the third digit is incremented when editorial
25、only changes have been incorporated in the document. ETSI ETSI TS 146 022 V14.0.0 (2017-04)53GPP TS 46.022 version 14.0.0 Release 141 Scope The present document gives the detailed requirements for the correct operation of the background acoustic noise evaluation, noise parameter encoding/decoding an
26、d 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 the present document are mandatory for implementation in all GSM MSs capable of supporting the half rate
27、 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 References The following documents contain provisions whi
28、ch, through reference in this text, constitute provisions of the present document. References are either specific (identified by date of publication, edition number, version number, etc.) or non-specific. For a specific reference, subsequent revisions do not apply. For a non-specific reference, the
29、latest version applies. In the case of a reference to a 3GPP document (including a GSM document), a non-specific reference implicitly refers to the latest version of that document in the same Release as the present document. 1 GSM 01.04: “Digital cellular telecommunication system (Phase 2+); Abbrevi
30、ations and acronyms“. 2 GSM 06.20: “Digital cellular telecommunications system (Phase 2+); Half rate speech transcoding“. 3 GSM 06.41: “Digital cellular telecommunications system (Phase 2+); Half rate speech; Discontinuous Transmission (DTX) for half rate speech traffic channels“. 4 GSM 06.42: “Digi
31、tal cellular telecommunications system (Phase 2+); “Half rate speech; Voice Activity Detector (VAD) for half rate speech traffic channels“. 5 GSM 06.06: “Digital cellular telecommunications system (Phase 2+); Half rate speech; ANSI-C code for the GSM half rate speech codec“. 3 Definitions, symbols a
32、nd abbreviations 3.1 Definitions For the purposes of the present document, the following terms and definitions 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. H(Z): combination of the short
33、 term (spectral) filter A(z) and the spectral weighting filter W(z). SID codeword: fixed bit pattern for labelling a traffic frame as a SID frame. SID field: bit positions of the SID codeword within a SID frame. SID frame: frame characterized by the SID (Silence Descriptor) codeword. It conveys info
34、rmation on the acoustic background noise. ETSI ETSI TS 146 022 V14.0.0 (2017-04)63GPP TS 46.022 version 14.0.0 Release 14SP flag: speech flag. speech frame: traffic frame that cannot be classified as a SID frame. VAD flag: Voice Activity Detector flag. W(Z): spectral weighting filter of the GSM half
35、 rate speech codec. Other definitions of terms used in the present document can be found in GSM 06.20 2 and GSM 06.41 3. The overall operation of DTX is described in GSM 06.41 3. 3.2 Symbols For the purposes of the present document, the following symbols apply: GS Energy tweak parameter. R0 Frame en
36、ergy value. R(i) Unquantised (normalized) autocorrelation sequence. rjOptimal reflection coefficient. 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 fir
37、st excitation vector as a fraction of the total excitation power at a subframe. 3.3 Abbreviations For the purposes of the present document, the following abbreviations apply: AFLAT Autocorrelation Fixed Point LAttice Technique (used in the GSM half rate speech codec for the vector quantization of th
38、e LPC coefficients) BSS Base Station System DTX Discontinuous Transmission ETS European Telecommunication Standard GSM Global System for Mobile communications MS Mobile StationSID SIlence Descriptor RX Receive TX TransmitVAD Voice Activity Detector VQ Vector QuantizationFor abbreviations not given i
39、n this subclause, see GSM 01.04 1. 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
40、 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. The present document specifies a solution to overcome this problem by generating synthetic nois
41、e similar to the transmit (TX) side background noise on the receive (RX) side. The comfort noise parameters are estimated on the TX side and transmitted to the RX side before the radio transmission is switched off and at a regular low rate afterwards. This allows the comfort noise to adapt to the ch
42、anges of the noise on the TX side. ETSI ETSI TS 146 022 V14.0.0 (2017-04)73GPP TS 46.022 version 14.0.0 Release 145 Functions on the transmit (TX) side The comfort noise evaluation algorithm uses the following parameters of the GSM half rate speech encoder, defined in GSM 06.20 2: - the unquantized
43、frame energy value R0; - the unquantized (normalized) autocorrelation sequence R(i) derived from the optimal reflection coefficients rj; - the quantized energy tweak parameter GS. These parameters give information on the level (R0 and GS) and the spectrum (R(i) of the background noise. Two of the ev
44、aluated comfort noise parameters (R0 and R(i) are encoded into a special frame, called a SIlence Descriptor (SID) frame, for transmission to the RX side. While the energy tweak parameter GS can be evaluated in the encoder and decoder in the same way as given in subclause 5.1, therefore no transmissi
45、on of GS is necessary. The SID frame also serves to initiate the comfort noise generation on the RX side, as a SID frame is always sent at the end of a speech burst, i.e. before the radio transmission is terminated. The scheduling of SID or speech frames on the radio path is described in GSM 06.41 3
46、. 5.1 Background acoustic noise evaluation The comfort noise parameters to be encoded into a SID frame are calculated over 8 consecutive frames marked with Voice Activated Detector (VAD) flag = “0“, as follows: The frame energy values shall be averaged according to the equation: 7 mean (R0j) = 1/8 S
47、UM R0j-n; n=0 where: R0j is the frame energy value of the current frame j (n=0); R0j-n is the frame energy of the previous frames (n=1,.,7); n is the averaging period index n=0,1,.,7; j is the frame index. The averaged value mean(R0j) is encoded using the same encoding table that is also used by the
48、 GSM half rate speech codec for the encoding of the non-averaged R0 values in ordinary speech encoding mode. The (normalized) autocorrelation sequence R(i) shall be averaged according to the equation: 7 mean (Rj(i) = 1/8 SUM Rj-n(i) i = 0,1,2.,10; n=0 where: Rj(i) is the ith autocorrelation value of
49、 the current frame j (n=0); Rj-n(i) is the ith autocorrelation value of one of the previous frames (n=1,.,7); n is the averaging period index n=0,1.,7; j is the frame index. ETSI ETSI TS 146 022 V14.0.0 (2017-04)83GPP TS 46.022 version 14.0.0 Release 14The averaged values mean(Rj(i) are used as input parameters of the Autocorrelation Fixed Point LAttice Technique (AFLAT) recursion algorithm which calculates the Vector Quantization (VQ) indices of the reflection coefficients, see GSM 06.20 2. The SID frame containing t
