1、 ETSI TS 126 192 V15.0.0 (2018-07) 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 15.0.0
2、 Release 15) TECHNICAL SPECIFICATION ETSI ETSI TS 126 192 V15.0.0 (2018-07)13GPP TS 26.192 version 15.0.0 Release 15Reference RTS/TSGS-0426192vf00 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. ETSI 2018. All rights reserved. D
8、ECTTM, PLUGTESTSTM, UMTSTMand the ETSI logo are trademarks of ETSI registered for the benefit of its Members. 3GPPTM and LTETMare trademarks of ETSI registered for the benefit of its Members and of the 3GPP Organizational Partners. oneM2M logo is protected for the benefit of its Members. GSMand the
9、GSM logo are trademarks registered and owned by the GSM Association. ETSI ETSI TS 126 192 V15.0.0 (2018-07)23GPP TS 26.192 version 15.0.0 Release 15Intellectual Property Rights Essential patents IPRs essential or potentially essential to normative deliverables may have been declared to ETSI. The inf
10、ormation pertaining to these essential 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 th
11、e ETSI Secretariat. Latest updates 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 t
12、he updates on the ETSI Web server) which are, or may be, or may become, essential to the present document. Trademarks The present document may include trademarks and/or tradenames which are asserted and/or registered by their owners. ETSI claims no ownership of these except for any which are indicat
13、ed as being the property of ETSI, and conveys no right to use or reproduce any trademark and/or tradename. Mention of those trademarks in the present document does not constitute an endorsement by ETSI of products, services or organizations associated with those trademarks. Foreword This Technical S
14、pecification (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 references to the corresponding ETSI deliv
15、erables. 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“, “can“ and “cannot“ are to be inter
16、preted 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 126 192 V15.0.0 (2018-07)33GPP TS 26.192 version 15.0.0 Release 15Contents Intell
17、ectual Property Rights 2g3Foreword . 2g3Modal verbs terminology 2g3Foreword . 4g31 Scope 5g32 Normative references . 5g33 Definitions, symbols and abbreviations . 6g33.1 Definitions 6g33.2 Symbols 6g33.3 Abbreviations . 6g34 General . 7g35 Functions on the transmit (TX) side . 7g35.1 ISF evaluation
18、7g35.2 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-frame encoding . 10g36 Functions on the receive (RX) side 10g36.1 Averaging and decoding of the LP a
19、nd 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 V15.0.0 (2018-07)43GPP TS 26.192 version 15.0.0 Release 15Foreword This Technical Specification has been
20、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 noise generation in the narrowband telephony speech service employing the Adaptive Multi-Rate Wideband (AM
21、R-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 contents of this TS, it will be re-released by the TSG with an identifying change of release date and
22、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 control. y the second digit is incremented for all changes of substance, i.e. technical enhancements,
23、corrections, updates, etc. z the third digit is incremented when editorial only changes have been incorporated in the specification; ETSI ETSI TS 126 192 V15.0.0 (2018-07)53GPP TS 26.192 version 15.0.0 Release 151 Scope This document gives the detailed requirements for the correct operation of the b
24、ackground 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 requirements described in this document are mandatory for implementation in all UEs capable of supporting
25、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 downlink SCR will be used. In case of discrepancy between the requirements described in this document a
26、nd 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, provisions from other publications. These normative references are cited at the appropriate places i
27、n 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 amendment or revision. For undated references, the latest edition of the publication referred to appli
28、es. 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 concealment of lost frames “. 4 3GPP TS 26.193 : “AMR Wideband Speech Codec; Source Controlled Rate operation “
29、. 5 3GPP TS 26.201 : “AMR Wideband Speech Codec; Frame Structure“. ETSI ETSI TS 126 192 V15.0.0 (2018-07)63GPP TS 26.192 version 15.0.0 Release 153 Definitions, symbols and abbreviations 3.1 Definitions For the purpose of this document, the following definitions apply. Frame: Time interval of 20 ms
30、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 information on the acoustic background noise or inform the decoder that it should start generating backgr
31、ound 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_TYPE: Classification of the received traffic frame (defined in 4). Other definitions of terms used in
32、 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 vector variables. 1621. fffT=f Unquantized ISF vector 1621.fffT=f Quantized ISF vector f()mUnquantized ISF
33、vector of frame m $f()mQuantized ISF vector of frame m Averaged ISF parameter vector enlogLogarithmic frame energy enmeanlogAveraged logarithmic frame energy ISF parameter prediction residual Quantized ISF parameter prediction residual 3.3 Abbreviations For the purpose of this document , the followi
34、ng abbreviations apply. AMR Adaptive Multi-Rate AMR-WB Adaptive Multi-Rate Wideband CN Comfort Noise SCR Source Controlled Rate operation ( aka source discontinuous transmission ) UE User Equipment SID SIlence Descriptorfmeane$exnnab()=() ( ) ( ) ()=+xa xa xb xb11KETSI ETSI TS 126 192 V15.0.0 (2018-
35、07)73GPP TS 26.192 version 15.0.0 Release 15LP Linear Prediction ISP Immittance Spectral Pair ISF Immittance Spectral Frequency RSS Radio Subsystem RX Receive TX TransmitVAD Voice Activity Detector 4 General A basic problem when using SCR is that the background acoustic noise, which is transmitted t
36、ogether 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 this effect can be very annoying for the listener - especially in a car environment with high background
37、 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 transmit (TX) side background noise. The comfort noise parameters are estimated on the TX side and transm
38、itted 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 comfort noise evaluation algorithm uses the following parameters of the AMR-WB speech encoder, defined in 2:
39、 - 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 = ; The algorithm computes the following parameters to assist in comfort noise generation: - the weig
40、hted 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 the eight most recent frames). These parameters give information on the level ( enmeanlog) and the spect
41、rum ( ) 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 hangover logic is used to enhance the quality of the silence descriptor frames. A hangover of seven fr
42、ames 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 from the quantized ISFs and the logarithmic frame energy of the decoded speech signal. Therefore, no co
43、mfort 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 inactive mode in a very short time period, no hangover is used. Instead the previously used comfort nois
44、e 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 speech burst, i.e., before the transmission is terminated. The scheduling of SID or speech frames on the n
45、etwork path is described in 4. 5.1 ISF evaluation The comfort noise parameters to be encoded into a SID frame are calculated over N=8 consecutive frames marked with VAD=0, as follows: fmeanfmeanfmeanETSI ETSI TS 126 192 V15.0.0 (2018-07)83GPP TS 26.192 version 15.0.0 Release 15Prior to averaging the
46、 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 noise on the transmit side. First, the spectral distances from each of the ISF parameter vectors ()f i
47、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 parameter of the ISF parameter vector ()f i at frame i. To find the spectral distance Siof the ISF paramete
48、r 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) for all i=0,.,7, ij. The ISF parameter vector ()f i with the smallest spectral distance Siof all the I
49、SF 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 parameter 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 median replacement thre
