1、 ETSI TS 146 062 V14.0.0 (2017-04) Digital cellular telecommunications system (Phase 2+) (GSM); Comfort noise aspects for Enhanced Full Rate (EFR) speech traffic channels (3GPP TS 46.062 version 14.0.0 Release 14) TECHNICAL SPECIFICATION GLOBAL SYSTEM FOR MOBILE COMMUNICATIONSRETSI ETSI TS 146 062 V
2、14.0.0 (2017-04)13GPP TS 46.062 version 14.0.0 Release 14Reference RTS/TSGS-0446062ve00 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 la Sou
3、s-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 shall
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9、TS 146 062 V14.0.0 (2017-04)23GPP TS 46.062 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 and non
10、-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/). Pur
11、suant 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 present do
12、cument. 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 reference
13、s 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 not“, “
14、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 146 062 V14.0.0 (2017-04)33GPP TS 46.062 version
15、 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 . 7g35 Functions on the transmit (TX) side . 7
16、g35.1 Background acoustic noise evaluation . 8g35.2 Modification of the speech encoding algorithm during SID frame generation 11g35.3 SID-frame encoding . 11g36 Functions on the receive (RX) side 12g36.1 Averaging and decoding of the LP and fixed codebook gain parameters 12g36.2 Comfort noise genera
17、tion and updating 14g37 Computational details . 15g3Annex A (informative): Change history . 16g3History 17g3ETSI ETSI TS 146 062 V14.0.0 (2017-04)43GPP TS 46.062 version 14.0.0 Release 14Foreword This Technical Specification has been produced by the 3rdGeneration Partnership Project (3GPP). The pres
18、ent document defines operation of the background acoustic noise evaluation, noise parameter encoding/decoding and comfort noise generation in Mobile Stations (MSs) and Base Station Systems (BSSs) during Discontinuous Transmission (DTX) on Enhanced Full Rate speech traffic channels within the digital
19、 cellular telecommunications system. The contents of the present document are subject to continuing 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 da
20、te and an increase in version number as follows: Version x.y.z where: x the first digit: 1 presented 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. techni
21、cal enhancements, corrections, updates, etc. z the third digit is incremented when editorial only changes have been incorporated in the document. ETSI ETSI TS 146 062 V14.0.0 (2017-04)53GPP TS 46.062 version 14.0.0 Release 141 Scope The present document gives the detailed requirements for the correc
22、t operation of the background acoustic noise evaluation, noise parameter encoding/decoding and comfort noise generation in Mobile Stations (MSs) and Base Station Systems (BSSs) during Discontinuous Transmission (DTX) on Enhanced Full Rate speech traffic channels. The requirements described in the pr
23、esent document are mandatory for implementation in all GSM MSs capable of supporting the Enhanced Full Rate speech traffic channel. The receiver requirements are mandatory for implementation in all GSM BSSs capable of supporting the Enhanced Full Rate speech traffic channel, the transmitter requirem
24、ents only for those where downlink DTX will be used. In case of discrepancy between the requirements described in the present document and the fixed point computational description of these requirements contained in GSM 06.53 2, the description in GSM 06.53 2 will prevail. 2 References The following
25、 documents contain provisions which, 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. F
26、or a non-specific reference, the 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 telecommuni
27、cations system (Phase 2+); Abbreviations and acronyms“. 2 GSM 06.53: “Digital cellular telecommunications system (Phase 2+); ANSI-C code for the GSM Enhanced Full Rate (EFR) speech codec“. 3 GSM 06.60: “Digital cellular telecommunications system (Phase 2+); Enhanced Full Rate (EFR) speech transcodin
28、g“. 4 GSM 06.61: “Digital cellular telecommunications system (Phase 2+); Substitution and muting of lost frame for Enhanced Full Rate (EFR) speech traffic channels“. 5 GSM 06.81: “Digital cellular telecommunications system (Phase 2+); Discontinuous transmission (DTX) for Enhanced Full Rate (EFR) spe
29、ech traffic channels“. 3 Definitions, symbols and 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 Enhanced Full Rate speech transcoder, also used as a short
30、term traffic frame. SID frame: frame characterized 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: bit positions of the SID codeword within a SID frame. ETSI ET
31、SI TS 146 062 V14.0.0 (2017-04)63GPP TS 46.062 version 14.0.0 Release 14speech frame: traffic frame that cannot be classified as a SID frame. VAD flag: Voice Activity Detection flag. SP flag: SPeech flag. Other definitions of terms used in the present document can be found in GSM 06.60 3 and GSM 06.
32、81 5. The overall operation of DTX is described in GSM 06.81 5. 3.2 Symbols For the purposes of the present document, the following symbols apply. Boldface symbols are used for vector variables. fTff f=12 10. Unquantized LSF vector $ $.$fTff f=12 10Quantized LSF vector f()mmth unquantized LSF vector
33、 of the frame $f()mmth quantized LSF vector of the frame $frefReference LSF parameter vector fmeanAveraged LSF parameter vector gcUnquantized fixed codebook gain $gcQuantized fixed codebook gain $gcrefReference fixed codebook gain gcmeanAveraged fixed codebook gain eLPLinear prediction residual sign
34、al e Computed LSF parameter prediction residual $e Quantized LSF parameter prediction residual Computed fixed codebook gain correction factor $ Quantized fixed codebook gain correction factor xnnab()=() ( ) ( ) ()=+xa xa xb xb11K 3.3 Abbreviations For the purposes of the present document, the follow
35、ing abbreviations apply: BSS Base Station Subsystem DTX Discontinuous Transmission LP Linear PredictionLSF Line Spectral Frequency LSP Line Spectral Pair ETSI ETSI TS 146 062 V14.0.0 (2017-04)73GPP TS 46.062 version 14.0.0 Release 14MS Mobile Station RX Receive SID SIlence Descriptor TX Transmit VAD
36、 Voice Activity Detector For abbreviations not given in this clause, see GSM 01.04 1. 4 General A basic problem when using DTX is that the background acoustic noise, which is transmitted together with the speech, would disappear when the radio transmission is cut, resulting in discontinuities of the
37、 background noise. Since the DTX switching can take place rapidly, it has been found that this effect can be very 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 the way
38、 to overcome this problem by generating on the receive (RX) side synthetic noise similar to the transmit (TX) side background noise. 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 afterw
39、ards. This allows the comfort noise to adapt to the changes of the noise on the TX side. 5 Functions on the transmit (TX) side The comfort noise evaluation algorithm uses the following parameters of the GSM Enhanced Full Rate speech encoder, defined in GSM 06.60 3: - the unquantized and quantized Li
40、near Prediction (LP) parameters, using the Line Spectral Pair (LSP) representation, where the unquantized Line Spectral Frequency (LSF) vector is given by fTff f=12 10. , the quantized LSF vector is given by $ $.$fTff f=12 10, and the two sets of unquantized and quantized LSF vectors (one for each h
41、alf of a frame) are given by f()1, f()2, $f()1and $f()2, respectively; - the quantized fixed-codebook gain $gc. The algorithm also computes the following parameters to assist in comfort noise generation: - the reference LSF parameter vector $fref(average of the quantized LSF parameters of the hangov
42、er period); - the averaged LSF parameter vector fmean(average of the LSF parameters of the eight most recent frames); - the reference fixed codebook gain $gcref(average of the quantized fixed codebook gain values of the hangover period); - the averaged fixed codebook gain gcmean(average of the fixed
43、 codebook gain values of the eight most recent frames); - the unquantized fixed codebook gain gc. These parameters give information on the level ( gc, $gc, $gcref, gcmean) and the spectrum ( f()1, f()2, $f()1, $f()2, $fref, fmean) of the background noise. Two of the evaluated comfort noise parameter
44、s ( fmeanand gcmean) are encoded into a special frame, called a Silence Descriptor (SID) frame, for transmission to the RX side. Since the reference LSF parameter vector $frefand the reference fixed codebook gain $gcrefcan be evaluated in the same way in the encoder and decoder, as given in clause 5
45、.1, no transmission of these parameters is necessary. ETSI ETSI TS 146 062 V14.0.0 (2017-04)83GPP TS 46.062 version 14.0.0 Release 14The averaged LSF parameter and fixed codebook gain values, fmeanand gcmean, are computed in the encoder using both quantized and unquantized parameter values if the pe
46、riod of the eight most recent frames (the SID averaging period) is overlapping with the hangover period (the parameters from the frames overlapping with the hangover period have quantized values, while the parameters of the more recent frames of the SID averaging period have unquantized values). If
47、the period of the eight most recent frames is non-overlapping with the hangover period, the averaged LSF parameter and fixed codebook gain values are computed using only unquantized parameter values. The SID frame also serves to initiate the comfort noise generation on the receive side, as a SID fra
48、me 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 06.81 5. 5.1 Background acoustic noise evaluation The comfort noise parameters to be encoded into a SID frame are calculated
49、 over N = 8 consecutive frames marked with VAD = 0, as follows: The averaged LSF parameter vector ()fmeani of the frame i shall be computed according to the equation: () ()ffmean mmniin=18121207()(1) where: ()f()mi is the mth (unquantized) LSF parameter vector of the current frame i (n = 0); ()f()min is the mth (quantized or unquantized) LSF parameter vector of one of the last frames (n = 1,., 7); n is the averaging period index (n = 0, 1,., 7); m is the LSF parameter vector index within a frame (1 or 2); i is th
