1、 ETSI TS 146 051 V14.0.0 (2017-04) Digital cellular telecommunications system (Phase 2+) (GSM); Enhanced Full Rate (EFR) speech processing functions; General description (3GPP TS 46.051 version 14.0.0 Release 14) TECHNICAL SPECIFICATION GLOBAL SYSTEM FOR MOBILE COMMUNICATIONSRETSI ETSI TS 146 051 V1
2、4.0.0 (2017-04)13GPP TS 46.051 version 14.0.0 Release 14Reference RTS/TSGS-0446051ve00 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 Sous
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9、S 146 051 V14.0.0 (2017-04)23GPP TS 46.051 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/). Purs
11、uant 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 doc
12、ument. 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 references
13、 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“, “c
14、an“ 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 146 051 V14.0.0 (2017-04)33GPP TS 46.051 version
15、14.0.0 Release 14Contents Intellectual Property Rights 2g3Foreword . 2g3Modal verbs terminology 2g3Foreword . 4g31 Scope 5g32 References 5g33 Definitions and abbreviations . 5g33.1 Definitions 5g33.2 Abbreviations . 6g34 General . 6g35 Enhanced Full Rate speech channel transcoding 7g36 Enhanced Full
16、 Rate speech channel discontinuous transmission (DTX) . 7g37 Enhanced Full Rate speech channel Voice Activity Detection (VAD) 8g38 Enhanced Full Rate speech channel comfort noise insertion . 8 g39 Enhanced Full Rate speech channel lost speech frame substitution and muting 9g310 Enhanced Full Rate co
17、dec homing . 9g311 Alternative Enhanced Full Rate implementation using the Adaptive Multi Rate 12.2 kbit/s mode. 9g3Annex A (informative): Change History 11g3History 12g3ETSI ETSI TS 146 051 V14.0.0 (2017-04)43GPP TS 46.051 version 14.0.0 Release 14Foreword This Technical Specification has been prod
18、uced by the 3rdGeneration Partnership Project (3GPP). 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 cha
19、nge 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 or greater indicates TSG approved document under change control. y the second digit is incremented for all changes of subst
20、ance, i.e. technical enhancements, corrections, updates, etc. z the third digit is incremented when editorial only changes have been incorporated in the document. ETSI ETSI TS 146 051 V14.0.0 (2017-04)53GPP TS 46.051 version 14.0.0 Release 141 Scope The present document is an introduction to GSM 06.
21、60 6, GSM 06.61 7, GSM 06.62 8, GSM 06.81 9 and GSM 06.82 10 ENs dealing with the speech processing functions in the Enhanced Full Rate channel of the GSM system. A general overview of the speech processing functions is given, with reference to the ENs where each function is specified in detail. 2 R
22、eferences The following 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 re
23、visions do not apply. For 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: “Digit
24、al cellular telecommunications system (Phase 2+); Abbreviations and acronyms“. 2 GSM 03.50: “Digital cellular telecommunications system (Phase 2+); Transmission planning aspects of the speech service in the GSM Public Land Mobile Network (PLMN) system“. 3 GSM 05.03: “Digital cellular telecommunicati
25、ons system (Phase 2+); Channel coding“. 4 GSM 06.53: “Digital cellular telecommunications system (Phase 2+); ANSI-C code for the GSM Enhanced Full Rate (EFR) speech codec“. 5 GSM 06.54: “Digital cellular telecommunications system (Phase 2+); Test vectors for the GSM Enhanced Full Rate (EFR) speech c
26、odec“. 6 GSM 06.60: “Digital cellular telecommunications system (Phase 2+); Enhanced Full Rate (EFR) speech transcoding“. 7 GSM 06.61: “Digital cellular telecommunications system (Phase 2+); Substitution and muting of lost frame for Enhanced Full Rate (EFR) speech traffic channels“. 8 GSM 06.62: “Di
27、gital cellular telecommunications system (Phase 2+); Comfort noise aspects for Enhanced Full Rate (EFR) speech traffic channels“. 9 GSM 06.81: “Digital cellular telecommunications system (Phase 2+); Discontinuous transmission (DTX) for Enhanced Full Rate (EFR) speech traffic channels“. 10 GSM 06.82:
28、 “Digital cellular telecommunications system (Phase 2+); Voice Activity Detector (VAD) for Enhanced Full Rate (EFR) speech traffic channels“. 3 Definitions and abbreviations 3.1 Definitions Definition of terms used in the present document can be found in GSM 06.60 6, GSM 06.61 7, GSM 06.62 8, GSM 06
29、.81 9 and GSM 06.82 10. ETSI ETSI TS 146 051 V14.0.0 (2017-04)63GPP TS 46.051 version 14.0.0 Release 143.2 Abbreviations For the purposes of the present document, the following abbreviations apply: ACELP Algebraic Code Excited Linear Prediction BFI Bad Frame Indication BSS Base Station System CCITT
30、Comit Consultatif International Tlgraphique et Tlphonique DTX Discontinuous Transmission ETS European Telecommunication Standard GSM Global System for Mobile communications MS Mobile StationPCM Pulse Code Modulated PLMN Public Land Mobile Network PSTN Public Switched Telephone Network RF Radio Frequ
31、ency RSS Radio SubSystem RX Receive SACCH Slow Associated Control CHannel SID SIlence Descriptor SP flag SPeech flag TAF Time Alignment Flag TX TransmitFor abbreviations not given in this subclause, see GSM 01.04 1. 4 General Figure 1 presents a reference configuration where the various speech proce
32、ssing functions are identified. In this figure, the relevant Standards for each function are also indicated. In figure 1, the audio parts including analogue to digital and digital to analogue conversion are included, to show the complete speech path between the audio input/output in the Mobile Stati
33、on (MS) and the digital interface of the PSTN. The detailed specification of the audio parts are contained in GSM 03.50 2. These aspects are only considered to the extent that the performance of the audio parts affect the performance of the speech transcoder. An alternative and fully interoperable i
34、mplementation using as a basis the 12.2 kbit/s mode of the Adaptive Multi Rate speech coder is described in section 11. ETSI ETSI TS 146 051 V14.0.0 (2017-04)73GPP TS 46.051 version 14.0.0 Release 141) 8-bit /A-law or -law (PCS 1900) PCM (CCITT recommendation G.711), 8 000 samples/s. 2) 13-bit unifo
35、rm PCM, 8 000 samples/s. 3) Voice Activity Detector (VAD) flag. 4) Encoded speech frame, 50 frames/s, 244 bits/frame. 5) SIlence Descriptor (SID) frame, 244 bits/frame. 6) SPeech (SP) flag, indicates whether information bits are speech or SID information. 7) Information bits delivered to the radio s
36、ubsystem. 8) Information bits received from the radio subsystem. 9) Bad Frame Indication. 10) SIlence Descriptor (SID) flag. 11) Time Alignment Flag (TAF), marks the position of the SID frame within the Slow Associated Control CHannel (SACCH) multiframe. Figure 1: Overview of audio processing functi
37、ons 5 Enhanced Full Rate speech channel transcoding As shown in figure 1, the speech encoder takes its input as a 13-bit uniform Pulse Code Modulated (PCM) signal either from the audio part of the Mobile Station or on the network side, from the Public Switched Telephone Network (PSTN) via an 8-bit/A
38、-law or -law (PCS 1900) to 13-bit uniform PCM conversion. The encoded speech at the output of the speech encoder is delivered to the channel coding function defined in GSM 05.03 3 to produce an encoded block consisting of 456 bits leading to a gross bit rate of 22,8 kbit/s. In the receive direction,
39、 the inverse operations take place. GSM 06.60 6 describes the detailed mapping between input blocks of 160 speech samples in 13-bit uniform PCM format to encoded blocks of 244 bits and from encoded blocks of 244 bits to output blocks of 160 reconstructed speech samples. The sampling rate is 8 000 sa
40、mple/s leading to a bit rate for the encoded bit stream of 12,2 kbit/s. The coding scheme is the so-called Algebraic Code Excited Linear Prediction, hereafter referred to as ACELP. GSM 06.60 6 describes the codec and GSM 06.53 4 defines the C code, thus enabling the verification of compliance to GSM
41、 06.60 6 to a high degree of confidence by use of a set of digital test sequences given in GSM 06.54 5. 6 Enhanced Full Rate speech channel discontinuous transmission (DTX) During a normal phone conversation, the participants alternate so that, on the average, each direction of transmission is occup
42、ied about 50 % of the time. Discontinuous transmission (DTX) is a mode of operation where the transmitters are switched on only for those frames which contain useful information. This may be done for the following two purposes: ETSI ETSI TS 146 051 V14.0.0 (2017-04)83GPP TS 46.051 version 14.0.0 Rel
43、ease 141) In the MS, battery life will be prolonged or a smaller battery could be used for a given operational duration. 2) The average interference level over the air interface is reduced, leading to better Radio Frequency (RF) spectrum efficiency. The overall DTX mechanism is implemented in the DT
44、X handlers (Transmit (TX) and Receive (RX) described in GSM 06.81 9 and requires the following functions: - a Voice Activity Detector (VAD) on the TX side, see GSM 06.82 10; - evaluation of the background acoustic noise on the TX side, in order to transmit characteristic parameters to the RX side, s
45、ee GSM 06.62 8; - generation of comfort noise on the RX side during periods where the radio transmission is turned off, see GSM 06.62 8. The transmission of comfort noise information to the RX side is achieved by means of a Silence Descriptor (SID) frame. The SID frame is transmitted at the end of s
46、peech bursts and serves as an end of speech marker for the RX side. In order to update the comfort noise characteristics at the RX side, SID frames are transmitted at regular intervals also during speech pauses. This also serves the purpose of improving the measurement of the radio link quality by t
47、he Radio SubSystem (RSS). The DTX handlers interwork with the RSS using flags. The RSS is in control of the actual transmitter keying on the TX side, and performs various pre-processing functions on the RX side. This is described in GSM 06.81 9. The speech flag (SP) indicates whether information bit
48、s are speech or SID information. The SP flag is calculated from the VAD flag by the TX DTX handler. When SID information is transmitted (SP=“0“) the operation of the speech encoder is modified to reduce the remaining computation for that frame. This is described in GSM 06.62 8. 7 Enhanced Full Rate
49、speech channel Voice Activity Detection (VAD) The Enhanced Full Rate VAD function is described in GSM 06.82 10. The input to the VAD is a set of parameters computed by the Enhanced Full Rate speech encoder defined in GSM 06.60 6. The VAD uses this information to decide whether each 20 ms speech coder frame contains speech or not. Note that the VAD flag is an input to TX DTX handler and does not control the transmitter keying directly. GSM 06.82 10 describes the VAD algorithm and GSM 06.53
