1、 ETSI TS 126 192 V14.0.0 (2017-04) Digital cellular telecommunications system (Phase 2+) (GSM); Universal Mobile Telecommunications System (UMTS); LTE; Speech codec speech processing functions; Adaptive Multi-Rate - Wideband (AMR-WB) speech codec; Comfort noise aspects (3GPP TS 26.192 version 14.0.0
2、 Release 14) TECHNICAL SPECIFICATION ETSI ETSI TS 126 192 V14.0.0 (2017-04)13GPP TS 26.192 version 14.0.0 Release 14Reference RTS/TSGS-0426192ve00 Keywords GSM,LTE,UMTS 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
3、562 00017 - NAF 742 C Association but non lucratif enregistre 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
4、 any electronic and/or print versions of the present document shall not be modified without the prior written authorization of ETSI. In case of any existing or perceived difference in contents between such versions and/or in print, the only prevailing document is the print of the Portable Document F
5、ormat (PDF) version kept on a specific network drive within ETSI Secretariat. Users of the present document should be aware that the document may be subject to revision or change of status. Information on the current status of this and other ETSI documents is available at https:/portal.etsi.org/TB/E
6、TSIDeliverableStatus.aspx If you find errors in the present document, please send your comment to one of the following services: https:/portal.etsi.org/People/CommiteeSupportStaff.aspx Copyright Notification No part may be reproduced or utilized in any form or by any means, electronic or mechanical,
7、 including photocopying and microfilm except as authorized by written permission of ETSI. The content of the PDF version shall not be modified without the written authorization of ETSI. The copyright and the foregoing restriction extend to reproduction in all media. European Telecommunications Stand
8、ards Institute 2017. All rights reserved. DECTTM, PLUGTESTSTM, UMTSTMand the ETSI logo are Trade Marks of ETSI registered for the benefit of its Members. 3GPPTM and LTE are Trade Marks of ETSI registered for the benefit of its Members and of the 3GPP Organizational Partners. GSM and the GSM logo are
9、 Trade Marks registered and owned by the GSM Association. ETSI ETSI TS 126 192 V14.0.0 (2017-04)23GPP TS 26.192 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 es
10、sential IPRs, if any, is publicly available for ETSI members 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 upda
11、tes are available on the ETSI Web server (https:/ipr.etsi.org/). 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 serv
12、er) which are, or may be, or may become, essential to the present 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 identiti
13、es or GSM identities. These should be interpreted as being references 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 no
14、t“, “should“, “should not“, “may“, “need not“, “will“, “will 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 cit
15、ation. ETSI ETSI TS 126 192 V14.0.0 (2017-04)33GPP TS 26.192 version 14.0.0 Release 14Contents Intellectual Property Rights 2g3Foreword . 2g3Modal verbs terminology 2g3Foreword . 4g31 Scope 5g32 Normative references . 5g33 Definitions, symbols and abbreviations . 6g33.1 Definitions 6g33.2 Symbols 6g
16、33.3 Abbreviations . 6g34 General . 7g35 Functions on the transmit (TX) side . 7g35.1 ISF evaluation 8g35.2 Frame energy calculation . 9g35.3 Analysis of the variation and stationarity of the background noise 9g35.4 Modification of the speech encoding algorithm during SID frame generation 9g35.4 SID
17、-frame encoding . 10g36 Functions on the receive (RX) side 10g36.1 Averaging and decoding of the LP and energy parameters 10g36. 2 Comfort noise generation and updating 11g37 Computational details and bit allocation 12g3Annex A (informative): Change history . 13g3History 14g3ETSI ETSI TS 126 192 V14
18、.0.0 (2017-04)43GPP TS 26.192 version 14.0.0 Release 14Foreword This Technical Specification has been produced by the 3GPP. The present document defines the detailed requirements for the correct operation of the background acoustic noise evaluation, noise parameter encoding/decoding and comfort nois
19、e generation in the narrowband telephony speech service employing the Adaptive Multi-Rate Wideband (AMR-WB) speech coder within the 3GPP 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
20、contents of this TS, 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 presented to TSG for information; 2 presented to TSG for approval; 3 Indicates TSG approved document under change
21、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 only changes have been incorporated in the specification; ETSI ETSI TS 126 192 V14.0.0 (2017-04)53GPP TS 26.192 version 14.
22、0.0 Release 141 Scope This document gives the detailed requirements for the correct operation of the background acoustic noise evaluation, noise parameter encoding/decoding and comfort noise generation for the AMR Wideband (AMR-WB) speech codec during Source Controlled Rate (SCR) operation. The requ
23、irements described in this document are mandatory for implementation in all UEs capable of supporting the AMR-WB speech codec. The receiver requirements are mandatory for implementation in all networks capable of supporting the AMR-WB speech codec, the transmitter requirements only for those where d
24、ownlink SCR will be used. In case of discrepancy between the requirements described in this document and the fixed point computational description of these requirements contained in 1, the description in 1 will prevail. 2 Normative references This document incorporates by dated and undated reference
25、, 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 document only when incorporated in it by
26、amendment or revision. For undated references, the latest edition of the publication referred to applies. 1 3GPP TS 26.173 : “AMR Wideband Speech Codec; ANSI-C code“. 2 3GPP TS 26.190 : “AMR Wideband Speech Codec; Transcoding functions“. 3 3GPP TS 26.191 : “AMR Wideband Speech Codec; Error concealme
27、nt of lost frames “. 4 3GPP TS 26.193 : “AMR Wideband Speech Codec; Source Controlled Rate operation “. 5 3GPP TS 26.201 : “AMR Wideband Speech Codec; Frame Structure“. ETSI ETSI TS 126 192 V14.0.0 (2017-04)63GPP TS 26.192 version 14.0.0 Release 143 Definitions, symbols and abbreviations 3.1 Definit
28、ions For the purpose of this document, the following definitions apply. Frame: Time interval of 20 ms corresponding to the time segmentation of the adaptive multi-rate wideband speech transcoder, also used as a short term for traffic frame. SID frames: Special Comfort Noise frames. It may convey inf
29、ormation on the acoustic background noise or inform the decoder that it should start generating background noise. Speech frame: Traffic frame that cannot be classified as a SID frame. VAD flag: Voice Activity Detection flag. TX_TYPE: Classification of the transmitted traffic frame (defined in 4). RX
30、_TYPE: Classification of the received traffic frame (defined in 4). Other definitions of terms used in this document can be found in 2 and 4. The overall operation of SCR is described in 4. 3.2 Symbols For the purpose of this document, the following symbols apply. Boldface symbols are used for vecto
31、r variables. 1621. fffT=f Unquantized ISF vector 1621.fffT=f Quantized ISF vector f()mUnquantized ISF vector of frame m $f()mQuantized ISF vector of frame m Averaged ISF parameter vector enlogLogarithmic frame energy enmeanlogAveraged logarithmic frame energy ISF parameter prediction residual Quanti
32、zed ISF parameter prediction residual 3.3 Abbreviations For the purpose of this document , the following abbreviations apply. AMR Adaptive Multi-Rate AMR-WB Adaptive Multi-Rate Wideband CN Comfort Noise SCR Source Controlled Rate operation ( aka source discontinuous transmission ) fmeane$exnnab()=()
33、 ( ) ( ) ()=+xa xa xb xb11KETSI ETSI TS 126 192 V14.0.0 (2017-04)73GPP TS 26.192 version 14.0.0 Release 14UE User Equipment SID SIlence DescriptorLP Linear Prediction ISP Immittance Spectral Pair ISF Immittance Spectral Frequency RSS Radio Subsystem RX Receive TX TransmitVAD Voice Activity Detector
34、4 General A basic problem when using SCR is that the background acoustic noise, which is transmitted together with the speech, would disappear when the transmission is cut, resulting in discontinuities of the background noise. Since the SCR switching can take place rapidly, it has been found that th
35、is 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. This document specifies the way to overcome this problem by generating on the receive (RX) side synthetic noise similar to the tra
36、nsmit (TX) side background noise. The comfort noise parameters are estimated on the TX side and transmitted to the RX side at a regular rate when speech is not present. 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 comfor
37、t noise evaluation algorithm uses the following parameters of the AMR-WB speech encoder, defined in 2: - the unquantized Linear Prediction (LP) parameters, using the Immittance Spectral Pair (ISP) representation, where the unquantized Immittance Spectral Frequency (ISF) vector is given by 1621fffT.f
38、 = ; The algorithm computes the following parameters to assist in comfort noise generation: - the weighted averaged ISF parameter vector (weighted average of the ISF parameters of the eight most recent frames); - the averaged logarithmic frame energy enmeanlog(average of the logarithmic energy of th
39、e eight most recent frames). These parameters give information on the level ( enmeanlog) and the spectrum ( ) of the background noise. The evaluated comfort noise parameters ( and enmeanlog) are encoded into a special frame, called a Silence Descriptor (SID) frame for transmission to the RX side. A
40、hangover logic is used to enhance the quality of the silence descriptor frames. A hangover of seven frames is added to the VAD flag so that the coder waits with the switch from active to inactive mode for a period of seven frames, during that time the decoder can compute a silence descriptor frame f
41、rom the quantized ISFs and the logarithmic frame energy of the decoded speech signal. Therefore, no comfort noise description is transmitted in the first SID frame after active speech. If the background noise contains transients which will cause the coder to switch to active mode and then back to in
42、active mode in a very short time period, no hangover is used. Instead the previously used comfort noise frames are used for comfort noise generation. The first SID frame also serves to initiate the comfort noise generation on the receive side, as a first SID frame is always sent at the end of a spee
43、ch burst, i.e., before the transmission is terminated. The scheduling of SID or speech frames on the network path is described in 4. fmeanfmeanfmeanETSI ETSI TS 126 192 V14.0.0 (2017-04)83GPP TS 26.192 version 14.0.0 Release 145.1 ISF evaluation The comfort noise parameters to be encoded into a SID
44、frame are calculated over N=8 consecutive frames marked with VAD=0, as follows: Prior to averaging the ISF parameters over the CN averaging period, a median replacement is performed on the set of ISF parameters to be averaged, to remove the parameters which are not characteristic of the background n
45、oise on the transmit side. First, the spectral distances from each of the ISF parameter vectors ()f i to the other ISF parameter vectors ()f j , i=0,.,7, j=0,.,7, ij, within the CN averaging period are approximated according to the equation: () ()=1612kjiijkfkfR , (1) where ()fkiis the kth ISF param
46、eter of the ISF parameter vector ()f i at frame i. To find the spectral distance Siof the ISF parameter vector ()f i to the ISF parameter vectors ()f j of all the other frames j=0,.,7, ji, within the CN averaging period, the sum of the spectral distances Rijis computed as follows: ,7,0=ijjijiRS (2)
47、for all i=0,.,7, ij. The ISF parameter vector ()f i with the smallest spectral distance Siof all the ISF parameter vectors within the CN averaging period is considered as the median ISF parameter vector fmedof the averaging period, and its spectral distance is denoted as Smed. The median ISF paramet
48、er vector is considered to contain the best representation of the short-term spectral detail of the background noise of all the ISF parameter vectors within the averaging period. If there are ISF parameter vectors ()f j within the CN averaging period with SSTHjmedmed , (3) where THmed= 225. is the m
49、edian replacement threshold, then at most two of these ISF parameter vectors (the ISF parameter vectors causing THmedto be exceeded the most) are replaced by the median ISF parameter vector prior to computing the averaged ISF parameter vector fmean. The set of ISF parameter vectors obtained as a result of the median replacement are denoted as () f ni, where n is the index of the current frame, and i is the averaging period index (i=0,.,7). When the median replacement is performed at the end of the hangover perio
