1、 ETSI TR 146 076 V14.0.0 (2017-04) Digital cellular telecommunications system (Phase 2+) (GSM); Adaptive Multi-Rate (AMR) speech codec; Study phase report (3GPP TR 46.076 version 14.0.0 Release 14) TECHNICAL REPORT GLOBAL SYSTEM FOR MOBILE COMMUNICATIONSRETSI ETSI TR 146 076 V14.0.0 (2017-04)13GPP T
2、R 46.076 version 14.0.0 Release 14Reference RTR/TSGS-0446076ve00 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、7-04)23GPP TR 46.076 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-members, and can be fo
10、und 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/). Pursuant to the ETSI IPR P
11、olicy, 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 document. Foreword This T
12、echnical Report (TR) 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 de
13、liverables. 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 “should“, “should not“, “may“, “need not“, “will“, “will not“, “can“ and “cannot“ are to be interpreted as described
14、 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 TR 146 076 V14.0.0 (2017-04)33GPP TR 46.076 version 14.0.0 Release 14Contents Intellectual Property Rig
15、hts 2g3Foreword . 2g3Modal verbs terminology 2g3Foreword . 5g3Executive summary and recommendations 6g3Introduction . 6g3Benefits 6g3Performance 6g3Risk areas 7g3Codec development and selection . 7g3Recommendations . 8g30 Scope 9g31 Goals of AMR codec 9g32 Terminology . 9g33 Overview of the AMR syst
16、em and its applications 9g33.1 Basic operation . 9g33.2 Application scenarios . 10g34 Development Time-scales 10g35 Baseline description and working assumptions 11g35.1 Generic operation . 11g35.2 Constraints 11g35.3 Speech and channel codecs 12g35.4 Rate adaptation . 13g35.4.1 Channel mode adaptati
17、on 13g35.4.2 Codec mode adaptation . 13g35.5 Support of TFO 13g35.6 Support of DTX 14g35.7 Support of 8 and 16 kbit/s A-ter sub-multiplexing . 14g35.8 Active noise suppression 14g36 Feasibility issues 14g36.1 Codec performance. 14g36.1.1 Basic, error and background noise performance . 15g36.1.2 Tand
18、eming 16g36.1.3 Seamless codec mode bit-rate changes . 16g36.1.4 Complexity . 16g36.2 Quality and Capacity benefits of AMR 17g36.2.1 General AMR performance. 17g36.2.2 Improved coverage from the improved robustness in FR mode . 17g36.2.3 Capacity benefits from the improved robustness in FR mode 18g3
19、6.2.4 Quality/capacity trade-offs by use of the HR mode 18g36.2.5 System aspects of capacity/quality . 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 performanc
20、e 22g36.3.5 Location of codec mode and channel mode control 23g36.3.6 Radio resource allocation 23g36.4 Support of other features 24g36.4.1 TFO . 24g3ETSI ETSI TR 146 076 V14.0.0 (2017-04)43GPP TR 46.076 version 14.0.0 Release 146.4.2 DTX 24g36.4.3 Power control 24g36.4.4 Handover 25g36.4.5 8 and 16
21、 kbit/s A-ter sub-multiplexing . 25g36.5 Wideband service option 25g37 Requirements specification 26g38 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 27g
22、39.4 Schedule . 28g39.5 Programme management 29g310 Open issues and risks . 29g311 Recommendations 30g3Annex A: Terminology 31g3Annex B: Application scenarios 34g3Annex C: Codec requirement specification . 35g3C.1 Static conditions . 35g3C.2 Dynamic conditions 37g3Annex D: AMR implementation require
23、ments . 38g3D.1 Network 38g3D.2 MS 40g3Annex E: Speech traffic channel simulator . 42g3Annex F: Schedule for AMR development 44g3Annex G: Work Item Description for AMR 46g3Annex H: Change history 48g3History 49g3ETSI ETSI TR 146 076 V14.0.0 (2017-04)53GPP TR 46.076 version 14.0.0 Release 14Foreword
24、This Technical Specification has been produced by the 3rdGeneration Partnership Project (3GPP). The present 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 f
25、ollowing 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 information; 2 presented
26、 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 incorporated in the
27、document. ETSI ETSI TR 146 076 V14.0.0 (2017-04)63GPP TR 46.076 version 14.0.0 Release 14Executive summary 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 fe
28、asibility but also the benefits of AMR in realistic applications, the development plan, time-scales and 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 leve
29、l of error protection, the AMR system adapts to local radio channel and traffic conditions and selects 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 importa
30、nt benefits: - improved speech quality in both half-rate and full-rate modes by means of codec mode adaptation 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
31、codec mode adaptation; this can be controlled by the network operator on a cell by cell basis; - improved 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 o
32、perating a tighter frequency re-use pattern; - ability to tailor AMR operation to meet the many different 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 benefit
33、s, a wide-ranging study has been carried out. This has considered not only speech and channel codec performance, 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 S
34、tudy Phase has prevented a thorough assessment of all aspects. However, it has been possible to assess 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 s
35、ome of the main applications of AMR, assuming certain system assumptions such as frequency hopping and 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
36、a C/I of 4 dB, measured at the input to the channel equalizer. This will give coverage in-fill advantages 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 t
37、raded against each other in a controlled manner. Using as a reference an EFR/HR combination with a conventional 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 r
38、elatively insensitive to C/I. It has also been estimated that for a capacity improvement of about 30 % (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
39、to the local C/I distributions. These have proved to be difficult to estimate reliably. Other individual estimates have shown more optimistic results and the figures quoted probably represent the lower end of the range. ETSI ETSI TR 146 076 V14.0.0 (2017-04)73GPP TR 46.076 version 14.0.0 Release 14-
40、 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 adaptation) especially in background noise conditions and at low errors. Under these conditions, the quality level will be at
41、 least as good as that of FR. - The increased resilience channel errors in full-rate mode may allow a 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
42、 EFR codecs or data terminals should be handled, as they do not have the improved resilience to errors 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 perf
43、ormance: to achieve the wireline quality benchmark of G.728 in HR mode, the C/I threshold had to be increased 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 abov
44、e. - background noise: the original performance objective in HR mode was G.728 is better than EFR. This 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 ex
45、isting HR codec. - the difficulties of measuring C/I distributions representative of high capacity networks 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
46、 been made to illustrate the lower limit. Risk: medium. - channel and codec mode adaptation algorithms. 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. - channe
47、l quality metric. It is important that the estimate of the channel quality is sufficiently accurate to 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 SMG
48、11, 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 conc
49、lusion of the Study Phase, there remain open design issues. However, working assumptions have been reached for most critical areas and other open issues can be resolved in due course without prejudice. Codec development and selection It is recommended that the optimum AMR solution be selected from a number of candidate proposals. To promote integrated solutions with the greatest flexibility for innovative techniques, designers should submit complete solutions including not only the speech and channel codecs, but also the control and signaling system, subject to agreed constra
