1、 ETSI TS 126 094 V14.0.0 (2017-04) Digital cellular telecommunications system (Phase 2+) (GSM); Universal Mobile Telecommunications System (UMTS); LTE; Mandatory speech codec speech processing functions; Adaptive Multi-Rate (AMR) speech codec; Voice Activity Detector (VAD) (3GPP TS 26.094 version 14
2、.0.0 Release 14) TECHNICAL SPECIFICATION ETSI ETSI TS 126 094 V14.0.0 (2017-04)13GPP TS 26.094 version 14.0.0 Release 14Reference RTS/TSGS-0426094ve00 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
3、623 562 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 conten
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8、tandards 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
9、 are Trade Marks registered and owned by the GSM Association. ETSI ETSI TS 126 094 V14.0.0 (2017-04)23GPP TS 26.094 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 thes
10、e 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 the ETSI Secretariat. Latest
11、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 the updates on the ETSI Web
12、server) 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 iden
13、tities 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“, “shal
14、l not“, “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
15、 citation. ETSI ETSI TS 126 094 V14.0.0 (2017-04)33GPP TS 26.094 version 14.0.0 Release 14Contents Intellectual Property Rights 2g3Foreword . 2g3Modal verbs terminology 2g3Foreword . 4g31 Scope 5g32 References 5g33 Technical Description of VAD Option 1 5g33.1 Definitions, symbols and abbreviations 5
16、g33.1.1 Definitions 5g33.1.2 Symbols 5g33.1.2.1 Variables . 5g33.1.2.2 Constants. 6g33.1.2.3 Functions . 7g33.1.3 Abbreviations 7g33.2 General . 7g33.3 Functional description 7g33.3.1 Filter bank and computation of sub-band levels . 8g33.3.2 Pitch detection 10g33.3.3 Tone detection 10g33.3.4 Correla
17、ted Complex Signal Analysis (and detection) . 11g33.3.5 VAD decision . 11g33.3.5.1 Hangover addition . 12g33.3.5.2 Background noise estimation 14g34 Technical Description of VAD Option 2 16g34.1 Definitions, symbols and abbreviations 16g34.1.1 Definitions 16g34.1.2 Symbols 16g34.1.2.1 Variables . 16
18、g34.1.2.2 Constants. 17g34.1.2.3 Functions . 17g34.1.3 Abbreviations 18g34.2 General . 18g34.3 Functional description 18g34.3.1 Frequency Domain Conversion 19g34.3.2 Channel Energy Estimator 19g34.3.3 Channel SNR Estimator 20g34.3.4 Voice Metric Calculation 20g34.3.5 Frame SNR and Long-Term Peak SNR
19、 Calculation . 20g34.3.6 Negative SNR Sensitivity Bias . 21g34.3.7 VAD Decision 21g34.3.8 Spectral Deviation Estimator 22g34.3.9 Sinewave Detection 22g34.3.10 Background Noise Update Decision . 23g34.3.10 Background Noise Estimate Update . 23g35 Computational details . 24g3Annex A (informative) : Ch
20、ange history . 25g3History 26g3ETSI ETSI TS 126 094 V14.0.0 (2017-04)43GPP TS 26.094 version 14.0.0 Release 14Foreword This Technical Specification has been produced by the 3rdGeneration Partnership Project (3GPP). The contents of the present document are subject to continuing work within the TSG an
21、d 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 date and an increase in version number as follows: Version x.y.z where: x the first digit: 1 presented to TSG for informatio
22、n; 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. technical enhancements, corrections, updates, etc. z the third digit is incremented when editorial only changes have been incorp
23、orated in the document. ETSI ETSI TS 126 094 V14.0.0 (2017-04)53GPP TS 26.094 version 14.0.0 Release 141 Scope The present document specifies two alternatives for the Voice Activity Detector (VAD) to be used in the Discontinuous Transmission (DTX) as described in 3. Implementors of mobile station an
24、d infrastructure equipment conforming to the AMR specifications can choose which of the two VAD options to implement. There are no interoperability factors associated with this choice. The requirements are mandatory on any VAD to be used either in User Equipment (UE) or Base Station Systems (BSS)s t
25、hat utilize the AMR speech codec. 2 References 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. Fo
26、r a specific reference, subsequent revisions 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
27、present document. 1 3GPP TS 26.073: “Adaptive Multi-Rate (AMR); ANSI C source code“. 2 3GPP TS 26.090: “Transcoding functions“. 3 3 GPP TS 26.093: “Source Controlled Rate operation“. 4 ITU, The International Telecommunications Union, Blue Book, Vol. III, Telephone Transmission Quality, IXth Plenary
28、Assembly, Melbourne, 14-25 November, 1988, Recommendation G.711, Pulse code modulation (PCM) of voice frequencies. 3 Technical Description of VAD Option 1 3.1 Definitions, symbols and abbreviations 3.1.1 Definitions For the purposes of the present document, the following terms and definitions apply:
29、 frame: time interval of 20 ms corresponding to the time segmentation of the speech transcoder 3.1.2 Symbols For the purposes of the present document, the following symbols apply. 3.1.2.1 Variables bckr_estn background noise estimate burst_count counts length of a speech burst, used by VAD hangover
30、addition hang_count hangover counter, used by VAD hangover addition complex_hang_count hangover counter, used by CAD hangover addition complex_hang_timer hangover initator, used fo Complex Activity Estimation ETSI ETSI TS 126 094 V14.0.0 (2017-04)63GPP TS 26.094 version 14.0.0 Release 14lagcount pit
31、ch detection counter leveln signal level new_speech pointer of the speech encoder, points a buffer containing last received samples of a speech frame 2 noise_level average level of the background noise estimate oldlagcount lagcount of the previous frame pitch flag indicating presence of a periodic s
32、ignal complex_warning flag indicating the presence of a complex signal. best_corr_hp normalized and limited value from maximum HP filtered correlation vector corr_hp filtered best_corr_hp values pow_sum power of the input frame s(i) samples of the input framer snr_sum measure between input frame and
33、 noise estimate stat_count stationarity counter stat_rat measure indicating stationary T_opn open-loop lags 2 t0 autocorrelation maxima calculated by the open-loop pitch analysis 2 t1 signal power related to the autocorrelation maxima t0 2 tone flag indicating the presence of a tone vad_thr VAD thre
34、shold VAD_flag boolean VAD flag vadreg intermediate VAD decision complex_low intermediate complex signal decisions complex_high intermediate complex signal decisions 3.1.2.2 Constants ALPHA_UP1 constant for updating noise estimate (see clause 3.3.5.2) ALPHA_DOWN1 constant for updating noise estimate
35、 (see clause 3.3.5.2) ALPHA_UP2 constant for updating noise estimate (see clause 3.3.5.2) ALPHA_DOWN2 constant for updating noise estimate (see clause 3.3.5.2) ALPHA3 constant for updating noise estimate (see clause 3.3.5.2) ALPHA4 constant for updating average signal level (see clause 3.3.5.2) ALPH
36、A5 constant for updating average signal level (see clause 3.3.5.2) BURST_LEN_HIGH_NOISE constant for controlling VAD hangover addition (see clause 3.3.5.1) BURST_LEN_LOW_NOISE constant for controlling VAD hangover addition (see clause 3.3.5.1) COEFF3 coefficient for the filter bank (see clause 3.3.1
37、) COEFF5_1 coefficient for the filter bank (see clause 3.3.1) COEFF5_2 coefficient for the filter bank (see clause 3.3.1) HANG_LEN_HIGH_NOISE constant for controlling VAD hangover addition (see clause 3.3.5.1) HANG_LEN_LOW_NOISE constant for controlling VAD hangover addition (see clause 3.3.5.2) HAN
38、G_NOISE_THR constant for controlling VAD hangover addition (see clause 3.3.5.2) L_FRAME size of a speech frame, 160 L_NEXT length for the lookahead of the speech encoder, 40 LTHRESH threshold for pitch detection (see clause 3.3.2) NOISE_MAX maximum value for noise estimate (see clause 3.3.5.2) NOISE
39、_MIN minimum value for noise estimate (see clause 3.3.5.2) NTHRESH threshold for pitch detection (see clause 3.3.2) POW_PITCH_THR threshold for pitch detection (see clause 3.3.5) POW_COMPLEX_THR threshold for complex detection (see clause 3.3.5) STAT_COUNT threshold for stationary detection (see cla
40、use 3.3.5.2) CAD_MIN_STAT_COUNT minimum threshold after complex warning STAT_THR threshold for stationary detection (see clause 3.3.5.2) STAT_THR_LEVEL threshold for stationary detection (see clause 3.3.5.2) TONE_THR threshold for tone detection (see clause 3.3.3) VAD_P1 constant of computation for
41、VAD threshold (see clause 3.3.5.2) VAD_POW_LOW constant for controlling VAD hangover addition (see clause 3.3.5.1) VAD_SLOPE constant of computation for VAD threshold (see clause 3.3.5) VAD_THR_HIGH constant of computation for VAD threshold (see clause 3.3.5) CVAD_THRESH_ADAPT_HIGH constant for upda
42、ting complex_high ETSI ETSI TS 126 094 V14.0.0 (2017-04)73GPP TS 26.094 version 14.0.0 Release 14CVAD_THRESH_ADAPT_LOW constant for updating complex_low CVAD_THRESH_HANG constant for updating complex_hang_timer CVAD_HANG_LIMIT constant for initiating complex_hang_count CVAD_HANG_LENGTH constant for
43、resetting complex_hang_count 3.1.2.3 Functions + addition- subtraction * multiplication / division | x | absolute value of x AND Boolean ANDOR Boolean ORxnnab()=MIN(x,y) = MAX(x,y) = 3.1.3 Abbreviations For the purposes of the present document, the following abbreviations apply: ANSI American Nation
44、al Standards Institute DTX Discontinuous Transmission VAD Voice Activity Detector CAD Complex Activity Detection CNG Comfort Noise Generation 3.2 General The function of the VAD algorithm is to indicate whether each 20 ms frame contains signals that should be transmitted, i.e. speech, music or infor
45、mation tones. The output of the VAD algorithm is a Boolean flag (VAD_flag) indicating presence of such signals. 3.3 Functional description The block diagram of the VAD algorithm is depicted in figure 1. The VAD algorithm uses parameters of the speech encoder to compute the Boolean VAD flag (VAD_flag
46、). Samples of the Input frame (s(i) are divided into sub-bands and level of the signal in each band (leveln) is calculated. Input for the pitch detection function are open-loop lags (T_opn), which are calculated by open-loop pitch analysis of the speech encoder. The pitch detection function computes
47、 a flag (pitch) which indicates presence of pitch. Tone detection function calculates a flag (tone), which indicates presence of an information tone. Tones are detected based on pitch gain of the open-loop pitch analysis The pitch gain is estimated using autocorrelation values (t0 and t1) received f
48、rom the pitch analysis. Complex Signal Detection function calculates a flag (complex_warning), which indicates presence of a correlated complex signal such as music. Correlate complex signals are detected based on analysis of the correlation vector available in the open-loop pitch analysis.The VAD d
49、ecision function estimates background noise levels. Intermediate VAD decision is calculated based on the comparison of the background noise estimate and levels of the input frame (leveln). Finally, the VAD flag is calculated by adding hangover to the intermediate VAD decision. () ( ) ( ) ()=+xa xa xb xb11Kxyyyxx,ETSI ETSI TS 126 094 V14.0.0 (2017-04)83GPP TS 26.094 version 14.0.0 Release 14Figure 3.1: Simplified block diagram of the VAD algorithm: Op
