1、 ETSI TR 146 076 V15.0.0 (2018-07) Digital cellular telecommunications system (Phase 2+) (GSM); Adaptive Multi-Rate (AMR) speech codec; Study phase report (3GPP TR 46.076 version 15.0.0 Release 15) TECHNICAL REPORT GLOBAL SYSTEM FOR MOBILE COMMUNICATIONSRETSI ETSI TR 146 076 V15.0.0 (2018-07)13GPP T
2、R 46.076 version 15.0.0 Release 15Reference RTR/TSGS-0446076vf00 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-Prfecture de Grasse (
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9、15.0.0 (2018-07)23GPP TR 46.076 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 information pertaining to these essential IPRs, if any, is publicly available for ETSI members
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15、webapp.etsi.org/key/queryform.asp. Modal verbs terminology In the present document “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
16、 “must not“ are NOT allowed in ETSI deliverables except when used in direct citation. ETSI ETSI TR 146 076 V15.0.0 (2018-07)33GPP TR 46.076 version 15.0.0 Release 15Contents Intellectual Property Rights 2g3Foreword . 2g3Modal verbs terminology 2g3Foreword . 5g3Executive summary and recommendations 6
17、g3Introduction . 6g3Benefits 6g3Performance 6g3Risk areas 7g3Codec development and selection . 7g3Recommendations . 8g30 Scope 9g31 Goals of AMR codec 9g32 Terminology . 9g33 Overview of the AMR system and its applications 9g33.1 Basic operation . 9g33.2 Application scenarios . 9g34 Development Time
18、-scales 10g35 Baseline description and working assumptions 10g35.1 Generic operation . 11g35.2 Constraints 11g35.3 Speech and channel codecs 12g35.4 Rate adaptation . 12g35.4.1 Channel mode adaptation 12g35.4.2 Codec mode adaptation . 13g35.5 Support of TFO 13g35.6 Support of DTX 13g35.7 Support of
19、8 and 16 kbit/s A-ter sub-multiplexing . 13g35.8 Active noise suppression 14g36 Feasibility issues 14g36.1 Codec performance. 14g36.1.1 Basic, error and background noise performance . 14g36.1.2 Tandeming 15g36.1.3 Seamless codec mode bit-rate changes . 15g36.1.4 Complexity . 16g36.2 Quality and Capa
20、city benefits of AMR 16g36.2.1 General AMR performance. 16g36.2.2 Improved coverage from the improved robustness in FR mode . 17g36.2.3 Capacity benefits from the improved robustness in FR mode 17g36.2.4 Quality/capacity trade-offs by use of the HR mode 18g36.2.5 System aspects of capacity/quality .
21、 20g36.2.6 MS penetration 21g36.3 Codec adaptation 21g36.3.1 Codec mode 21g36.3.2 Channel mode . 22g36.3.3 Channel metrics (accuracy, update rate) . 22g36.3.4 Channel dynamics, effects on performance 22g36.3.5 Location of codec mode and channel mode control 23g36.3.6 Radio resource allocation 23g36.
22、4 Support of other features 24g36.4.1 TFO . 24g36.4.2 DTX 24g3ETSI ETSI TR 146 076 V15.0.0 (2018-07)43GPP TR 46.076 version 15.0.0 Release 156.4.3 Power control 24g36.4.4 Handover 25g36.4.5 8 and 16 kbit/s A-ter sub-multiplexing . 25g36.5 Wideband service option 25g37 Requirements specification 26g3
23、8 Implementation factors . 26g39 Codec development and selection 26g39.1 Test and selection methodologies . 26g39.2 Asymmetry of up and down links 27g39.3 Speech traffic channel simulation model 27g39.4 Schedule . 28g39.5 Programme management 28g310 Open issues and risks . 28g311 Recommendations 29g
24、3Annex A: Terminology 31g3Annex B: Application scenarios 34g3Annex C: Codec requirement specification . 35g3C.1 Static conditions . 35g3C.2 Dynamic conditions 36g3Annex D: AMR implementation requirements . 37g3D.1 Network 37g3D.2 MS 39g3Annex E: Speech traffic channel simulator . 41g3Annex F: Schedu
25、le for AMR development 43g3Annex G: Work Item Description for AMR 45g3Annex H: Change history 47g3History 48g3ETSI ETSI TR 146 076 V15.0.0 (2018-07)53GPP TR 46.076 version 15.0.0 Release 15Foreword This Technical Specification has been produced by the 3rdGeneration Partnership Project (3GPP). The pr
26、esent technical report contains the GSM Adaptive Multi-Rate (AMR) speech codec Study Phase Report. 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 r
27、e-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 or greater indicates TSG approved document under change control. y the second
28、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 document. ETSI ETSI TR 146 076 V15.0.0 (2018-07)63GPP TR 46.076 version 15.0.0 Release 15Executive sum
29、mary and recommendations Introduction As tasked by SMG in October 1996, SMG11 and SMG2 have conducted a study into the feasibility of the AMR codec concept. The study not only addressed technical feasibility but also the benefits of AMR in realistic applications, the development plan, time-scales an
30、d the resources needed to take the AMR codec and associated network support to completion of the standards. Benefits Unlike previous GSM speech codecs which operate at a fixed rate with a fixed level of error protection, the AMR system adapts to local radio channel and traffic conditions and selects
31、 the optimum channel (half- or full- rate) and codec mode (speech and channel bit rates) to deliver the best combination of speech quality and capacity. This flexibility provides a number of important benefits: - improved speech quality in both half-rate and full-rate modes by means of codec mode ad
32、aptation i.e. varying the balance between speech and channel coding for the same gross bit-rate; - ability to trade speech quality and capacity smoothly and flexibly by a combination of channel and codec mode adaptation; this can be controlled by the network operator on a cell by cell basis; - impro
33、ved robustness to channel errors under marginal radio signal conditions in full-rate mode. This increased robustness to errors and hence to interference may instead be used to increase capacity by operating a tighter frequency re-use pattern; - ability to tailor AMR operation to meet the many differ
34、ent needs of operators; - potential for improved handover and power control resulting from additional signaling transmitted rapidly in-band. To investigate the feasibility of realizing these benefits, a wide-ranging study has been carried out. This has considered not only speech and channel codec pe
35、rformance, but perhaps more critically, channel and codec mode adaptation, the associated signaling and the operation of AMR in realistic radio environments. The one-year timeframe allowed for the Study Phase has prevented a thorough assessment of all aspects. However, it has been possible to assess
36、 expected performance (quality and capacity) and to identify and assess the risks of the critical areas from a feasibility perspective. Performance The performance benefits have been estimated for some of the main applications of AMR, assuming certain system assumptions such as frequency hopping and
37、 making a number of simplifications: - in full-rate mode only, the robustness to high error levels is substantially increased such that the quality level of EFR at a C/I of 10dB is extended down to a C/I of 4 dB, measured at the input to the channel equalizer. This will give coverage in-fill advanta
38、ges in areas of marginal radio coverage. This equates to an improvement of sensitivity of between 4 dB and 6 dB depending on the robustness of the signaling channels; - quality and capacity can be traded against each other in a controlled manner. Using as a reference an EFR/HR combination with a con
39、ventional resource allocation, for the same capacity improvement, AMR will give an average quality improvement corresponding to about 70 % of the difference between FR and EFR. This improvement is relatively insensitive to C/I. It has also been estimated that for a capacity improvement of about 30 %
40、 (relative to FR only), 80 % of calls would have G.728 quality of better, i.e. “wireline“ quality. This tradeoff between % capacity improvement and % of mobiles having wireline quality is sensitive to the local C/I distributions. These have proved to be difficult to estimate reliably. Other individu
41、al estimates have shown more optimistic results and the figures quoted probably represent the lower end of the range. - In half-rate mode only which gives the maximum capacity advantage (in excess of 100 % as for normal half-rate), quality improvements are also given (deriving from codec mode adapta
42、tion) especially in background noise conditions and at low errors. Under these conditions, the quality level will be at least as good as that of FR. ETSI ETSI TR 146 076 V15.0.0 (2018-07)73GPP TR 46.076 version 15.0.0 Release 15- The increased resilience channel errors in full-rate mode may allow a
43、tighter frequency re-use giving capacity improvements estimated at up to 30 %, but at the expense of lower speech quality. However, it is unclear at present how terminals without AMR e.g. with FR or EFR codecs or data terminals should be handled, as they do not have the improved resilience to errors
44、 and the speech quality would be degraded. This application requires further study. Risk areas The main performance limitations and technical risk areas have been identified as follows: - codec performance: to achieve the wireline quality benchmark of G.728 in HR mode, the C/I threshold had to be in
45、creased from 10 dB to about 18 dB. This will allow the speech quality target still to be achieved but at the expense of lower capacity gain. This is already reflected in the performance results above. - background noise: the original performance objective in HR mode was G.728 is better than EFR. Thi
46、s is too demanding and was relaxed to “the better of GSM-FR or G.729“ quality for each type of background noise (vehicle, street, office). This still represents a substantial improvement over the existing HR codec. - the difficulties of measuring C/I distributions representative of high capacity net
47、works using other capacity enhancing techniques (e.g. power control, frequency hopping) has made it difficult to make accurate estimates of capacity and quality. Pessimistic forecasts have therefore been made to illustrate the lower limit. Risk: medium. - channel and codec mode adaptation algorithms
48、. These are crucial to the success of AMR operation and improvements to initial implementations will be possible to optimize performance for real network operating conditions. Risk: medium. - channel quality metric. It is important that the estimate of the channel quality is sufficiently accurate to
49、 ensure that the optimum codec mode is selected. While some solutions have been considered, the feasibility of providing such an accurate metric remains a risk. Risk assessment by SMG2, high; by SMG11, medium. - TFO. Although some potential candidate TFO solutions for AMR have been identified, effective solutions will require significant development. Risk to TFO: medium. - AMR system complexity. The AMR system is relatively complex and introduces new techniques. Risk level: medium. At the conclusion of the Study Phase, there remain open design issues. However, working assump
