1、ETSI EN 300 960 V8.0.1 (2000-11) European Standard (Telecommunications series) Digital cellular telecommunications system (Phase 2+); Full rate speech; Processing functions (GSM 06.01 version 8.0.1 Release 1999) COPYRIGHT European Telecommunications Standards InstituteLicensed by Information Handlin
2、g Services(GSM 06.01 version 8.0.1 Release 1999) 2 ETSI EN 300 960 V8.0.1 (2000-1 1) Reference REN/SMG-110601 Q8 Keywords Digital cellular telecommunications system, Global System for Mobile communications (GSM) ETSI 650 Route des Lucioles F-O6921 Sophia Antipolis Cedex - FRANCE Tel.: +33 4 92 94 42
3、 O0 Fax: +33 4 93 65 47 16 Siret No 348 623 562 00017 - NAF 742 C Association but non lucratif enregistre la Sous-prfecture de Grasse (06) No 7803/88 Important notice Individual copies of the present document can be downloaded from: htti3:lwww. etsi I oq The present document may be made available in
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6、: editor etsi.fr Copyright Notification No part may be reproduced except as authorized by written permission. The copyright and the foregoing restriction extend to reproduction in all media. 8 European Telecommunications Standards Institute 2000. All rights reserved. ETSI COPYRIGHT European Telecomm
7、unications Standards InstituteLicensed by Information Handling Services(GSM 06.01 version 8.0.1 Release 1999) 3 ETSI EN 300 960 V8.0.1 (2000-1 1) Contents Intellectual Property Rights 4 Foreword 4 1 Scope 5 2 References 5 3 Abbreviations . 6 4 Introduction 6 5 Full rate speech transcoding (GSM 06.10
8、) . 6 6 Full rate Discontinuous Transmission (DTX) (GSM 06.31) . 6 7 Full rate Voice Activity Detection (VAD) (GSM 06.32) 7 8 Full rate comfort noise insertion (GSM 06.12) 7 9 Full rate lost speech frame substitution and muting (GSM 06.11) 7 10 Full Rate codec homing (GSM 06.10, optional feature) .
9、8 11 Speech transmission functions of the half rate traffic channel 8 Annex A (informative): Change Request History 10 History . 11 ETSI COPYRIGHT European Telecommunications Standards InstituteLicensed by Information Handling Services(GSM 06.01 version 8.0.1 Release 1999) 4 ETSI EN 300 960 V8.0.1 (
10、2000-1 1) Intellectual 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-members, and can be found in ETSI SR O00 314: “Intellectua
11、l 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 ClattD:/www.etsP.c/iDr. Pursuant to the ETSI IPR Policy, no investigation, including I
12、PR searches, has been carried out by ETSI. No guarantee can be given as to the existence of other IPRs not referenced in ETSI SR O00 314 (or the updates on the ETSI Web server) which are, or may be, or may become, essential to the present document. Foreword This European Standard (Telecommunications
13、 series) has been produced by ETSI Technical Committee Special Mobile Group (SMG). The present document describes in general terms the speech processing functions within the digital cellular telecommunications system. The contents of the present document may be subject to continuing work within SMG
14、and may change following formal SMG approval. Should SMG modify the contents of the present document it will then be re-submitted for formal approval procedures by ETSI with an identifying change of release date and an increase in version number as follows: Version 8.x.y where: 8 GSM Phase 2+ Releas
15、e 1999. x the second digit is incremented for changes of substance, i.e. technical enhancements, corrections, updates, etc.; y the third digit is incremented when editorial only changes have been incorporated in the specification. National transposition dates Date of adoption of this EN Date of late
16、st announcement of this EN (doa): Date of latest publication of new National Standard or endorsement of this EN (dop/e): Date of withdrawal of any conflicting National Standard (dow): 3 November 2000 28 February 2001 31 August 2001 31 August 2001 ETSI COPYRIGHT European Telecommunications Standards
17、InstituteLicensed by Information Handling Services(GSM 06.01 version 8.0.1 Release 1999) 5 ETSI EN 300 960 V8.0.1 (2000-1 1) 1 Scope The present document is an introduction to the 06 series of the GSM technical specifications dealing with the Full rate speech processing functions in the GSM system.
18、A general overview of the speech processing parts is given with reference to the technical specifications where each part is specified in detail. 2 References The following documents contain provisions which, through reference in this text, constitute provisions of the present documen t. References
19、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 latest version applies. A non-specific reference to an ETS shall also be taken to refer to lat
20、er versions published as an EN with the same number. For this Release 1999 document, references to GSM documents are for Release 1999 versions (version 8.x.y). 141 151 171 191 u31 GSM 01.04: “Digital cellular telecommunications system (Phase 2+); Abbreviations and acronyms“. GSM 03 SO: “Digital cell
21、ular telecommunications system (Phase 2+); Transmission planning aspects of the speech service in the GSM Public Land Mobile Network (PLMN) system“. GSM 06.10: “Digital cellular telecommunications system (Phase 2+); Full rate speech; Transcoding “ . GSM 06.11: “Digital cellular telecommunications sy
22、stem (Phase 2+); Full rate speech; Substitution and muting of lost frames for full rate speech channels“. GSM 06.12: “Digital cellular telecommunications system (Phase 2+); Full rate speech; Comfort noise aspect for full rate speech traffic channels“. GSM 06.3 1 : “Digital cellular telecommunication
23、s system (Phase 2+); Full rate speech; Discontinuous Transmission (DTX) for full rate speech traffic channels“. GSM 06.32: “Digital cellular telecommunications system (Phase 2+); Voice Activity Detector (VAD) for full rate speech traffic channels“. GSM 06.02: “Digital cellular telecommunications sys
24、tem (Phase 2+); Half rate speech; Half rate speech processing functions“. 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 speech; Substitution and muting
25、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+); Half rate speech; Discontinuou
26、s 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“. ETSI COPYRIGHT European Telecommunications Standards InstituteLicensed by Informati
27、on Handling Services(GSM 06.01 version 8.0.1 Release 1999) 6 ETSI EN 300 960 V8.0.1 (2000-1 1) 3 Abbreviations Abbreviations used in the present document are listed in GSM 01.04 i. 4 Introduction Figure 1 presents a reference configuration where the various speech processing functions are identified
28、. In this figure, the relevant technical specifications 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 inpudoutput in the Mobile Station (MS) and the d
29、igital interface to the PSTN. The specification of the audio parts are contained in GSM 03.50 2 (Transmission plan aspects of the speech service in the GSM PLMN system). These aspects are only considered in the GSM 06-series to the extent that the performance of the audio parts affect the performanc
30、e of the speech transcoder. 5 Full rate speech transcoding (GSM 06.1 O) As shown in figure 1, the speech encoder takes its input as a 13 bit uniform PCM signal either ftom the audio part of the mobile station or on the network side, from the PSTN via an 8 bidA-law or y-law (PCS 1900) to 13 bit unifo
31、rm PCM conversion. The encoded speech at the output of the speech encoder is delivered to the channel coding function defined in GSM 05.03 to produce an encoded block consisting of 456 bits leading to a gross bit rate of 22,s kbids. In the receive direction, the inverse operations take place. GSM 06
32、.10 3 describes the detailed mapping between input blocks of 160 speech samples in 13 bit uniform PCM format to encoded blocks of 260 bits and from encoded blocks of 260 bits to output blocks of 160 reconstructed speech samples. The sampling rate is 8 O00 sample/s leading to an average bit rate for
33、the encoded bit stream of 13 kbids. The coding scheme is the so-called Regular Pulse Excitation - Long Term prediction - Linear Predictive Coder, here-after referred to as WE-LTP. The technical specification describes the codec down to the bit level, thus enabling the verification of compliance to t
34、he technical specification to a high degree of confidence by use of a set of digital test sequences. These test sequences are also described and are available on floppy disks. 6 Full rate Discontinuous Transmission (DTX) (GSM 06.31) During a normal conversation, the participants alternate so that, o
35、n the average, each direction of transmission is occupied 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: 1) in the MS, batt
36、ery life will be prolonged or a smaller battery could be used for a given operational duration; 2) the average interference level on the “air“ is reduced, leading to better spectrum efficiency. The overall DTX mechanism is implemented in the DTX handlers (TX and Rx) described in GSM 06.31 6 and requ
37、ires the following functions which are described in separate technical specifications: - - a Voice Activity Detector on the transmit side; evaluation of the background acoustic noise on the transmit side, in order to transmit characteristic parameters to the receive side; - generation on the receive
38、 side of a similar noise, called comfort noise, during periods where the radio transmission is cut. ETSI COPYRIGHT European Telecommunications Standards InstituteLicensed by Information Handling Services(GSM 06.01 version 8.0.1 Release 1999) 7 ETSI EN 300 960 V8.0.1 (2000-1 1) The transmission of co
39、mfort noise information to the receive side is achieved by means of a special kame (Silence descriptor = SID). This frame is transmitted at the end of speech bursts and serves as an end of speech marker for the receive side. In order to update the comfort noise characteristics at the receive side, S
40、ID kames are transmitted at regular intervals also during speech pauses. This also serves the purpose of improving the measurement of the radio link quality by the radio subsystem. For the overall DTX functionality, the DTX handlers interwork via various flags with the Radio Subsystem, which is in c
41、ontrol of the actual transmitter keying on the TX side and which performs various pre-processing functions on the Rx side. This is also described in GSM 06.31 6. A common terminology used throughout the GSM 06-series of technical specifications is also defined in the present documen t. 7 Full rate V
42、oice Activity Detection (VAD) (GSM 06.32) The input to the VAD is a set of parameters computed by the full-rate speech encoder defined in GSM 06.10 3. 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 ha
43、ndler and does not control the transmitter keying directly. The technical specification describes the VAD algorithm down to the bit level. The conventions used in the bit-exact specification are the same as those used in GSM 06.10 3. The verification of compliance to the technical specification is a
44、chieved by use of digital test sequences applied to the same interface as the test sequences for the speech codec. These test sequences are also described and are available on floppy disks. 8 Full rate comfort noise insertion (GSM 06.1 2) When switching the transmission on and off during DTX operati
45、on, the effect would be a modulation of the background noise at the receiving end if no precautions were taken. When transmission is on, the background noise is transmitted together with the speech to the receiving end. As the speech burst ends, the connection is off and the perceived noise would dr
46、op to a very low level. This step modulation of noise is perceived as very annoying and may reduce the intelligibility of speech if presented to a listener without modification. This so-called “noise contrast effect“ is reduced in the GSM system by inserting an artificial noise, termed comfort noise
47、, at the receiving end when speech is absent. GSM 06.12 5 deals with the detailed aspects of the comfort noise process: - - - the evaluation of the acoustic background noise in the transmitter; the noise parameter encoding (SID frames) and decoding; and the generation of comfort noise in the receive
48、r. The algorithm for updating the noise parameters during speech pauses is also defined. The comfort noise mechanism is based on the full rate speech codec defined in GSM 06.10 3. 9 Full rate lost speech frame substitution and muting (GSM 06.1 1) In the receiver, frames may be lost due to transmissi
49、on errors or kame stealing. GSM 06.11 4 describes the actions to be taken in these cases, both for lost speech frames and for lost SID-frames in DTX operation. In order to mask the effect of an isolated lost kame, a scheme is used, where the lost speech frame is substituted by a predicted frame based on previous frames. Insertion of silence frames is not allowed. For several lost frames in a row, some muting technique must be used to indicate to the customer that transmission is interrupted. ETSI COPYRIGHT European Telecommunications Standards InstituteLicensed
