1、 ETSI TR 126 914 V15.0.0 (2018-07) Digital cellular telecommunications system (Phase 2+) (GSM); Universal Mobile Telecommunications System (UMTS); LTE; Multimedia telephony over IP Multimedia Subsystem (IMS); Optimization opportunities (3GPP TR 26.914 version 15.0.0 Release 15) TECHNICAL REPORT ETSI
2、 ETSI TR 126 914 V15.0.0 (2018-07)13GPP TR 26.914 version 15.0.0 Release 15Reference RTR/TSGS-0426914vf00 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 348 623 562 00017 - NAF 742 C Association but non
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9、ned by the GSM Association. ETSI ETSI TR 126 914 V15.0.0 (2018-07)23GPP TR 26.914 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 IP
10、Rs, 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 updates are av
11、ailable 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 server) which
12、are, or may be, or may become, essential to the present document. Trademarks The present document may include trademarks and/or tradenames which are asserted and/or registered by their owners. ETSI claims no ownership of these except for any which are indicated as being the property of ETSI, and con
13、veys no right to use or reproduce any trademark and/or tradename. Mention of those trademarks in the present document does not constitute an endorsement by ETSI of products, services or organizations associated with those trademarks. Foreword This Technical Report (TR) has been produced by ETSI 3rd
14、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 deliverables. The cross reference between GSM, UMTS,
15、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 in clause 3.2 of the ETSI Drafting Rules (Verbal f
16、orms for the expression of provisions). “must“ and “must not“ are NOT allowed in ETSI deliverables except when used in direct citation. ETSI ETSI TR 126 914 V15.0.0 (2018-07)33GPP TR 26.914 version 15.0.0 Release 15Contents Intellectual Property Rights 2g3Foreword . 2g3Modal verbs terminology 2g3For
17、eword . 4g3Introduction 4g31 Scope 5g32 References 5g33 Definitions and abbreviations . 6g33.1 Definitions 6g33.2 Abbreviations . 7g34 Overview 7g34.1 General . 7g34.2 System description . 8g35 Assumptions . 8g35.1 General assumptions. 8g35.2 Channels . 9g35.3 Media components . 9g35.4 Use scenarios
18、 10g36 Basic point-to-point call in Release 6 . 10g36.1 General . 10g36.2 Session setup 10g36.3 Media flow . 11g36.3.1 General 11g36.3.2 Voice . 12g36.3.3 Video 12g37 Areas of optimizations 13g37.1 General . 13g37.2 Delay jitter handling . 13g37.3 Packet-loss handling . 13g37.4 Handling of inter-wor
19、king with CS 14g37.5 Handling of inter-working between UTRAN and GERAN 14g37.6 Inter-media synchronization . 14g37.7 SDU segmentation in UTRAN/GERAN 14g37.8 Rate Adaptation 15g37.9 Packetization Overheads 15g37.10 End-2-End Signalling . 15g38 Conclusions and recommendations 15g3Annex A: Change histo
20、ry 16g3History 17g3ETSI ETSI TR 126 914 V15.0.0 (2018-07)43GPP TR 26.914 version 15.0.0 Release 15Foreword This Technical Report has been produced by the 3rdGeneration Partnership Project (3GPP). The contents of the present document are subject to continuing work within the TSG and may change follow
21、ing 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 to T
22、SG 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 docum
23、ent. Introduction Multimedia telephony over IP (3GPP TS 22.973 2) is a standardized IMS telephony service in 3GPP Release 7 that builds on the IMS capabilities already provided in 3GPP Releases 5 and 6. The objective of defining a service is to specify the minimum set of capabilities required in the
24、 IP Multimedia Subsystem to secure multi-vendor and multi-operator inter-operability for Multimedia Telephony and related Supplementary Services. While the user experience of Multimedia telephony is expected to have some similarity to existing telephony services, the richer capabilities of IMS is ex
25、ploited. In particular, multiple media components, such as voice and video, can be used and dynamically added or dropped during a call. ETSI ETSI TR 126 914 V15.0.0 (2018-07)53GPP TR 26.914 version 15.0.0 Release 151 Scope The present document: - identifies opportunities for optimization of service
26、quality and efficiency of Multimedia telephony over IP in a qualitative sense; - provides the basis for developing a set of optional backward-compatible tools implementing such optimizations. The optimized multimedia telephony targets many different system configurations and operating conditions, e.
27、g. GERAN, UTRAN, inter-working between GERAN, UTRAN, GAN, and different PLMNs. Of the various use cases for multimedia telephony, the main focus of the present document is on voice calls, but the focus also includes other core media components, such as video. In particular, areas with optimization o
28、pportunities include handling of degraded channels, delay jitter, packet losses, efficiency, inter-working with other voice systems, etc. The scope includes proposing solutions that maintain backward compatibility in order to ensure seamless inter-working with existing services available in the CS d
29、omain, such as CS voice telephony and 3G-324M, as well as with terminals of earlier 3GPP releases. Alignment with legacy media formats avoids transcoding and even allows realizing at least parts of the optimization gains. All optimizations are hence based on the default codecs specified in 3GPP TS 2
30、6.235 3 and 3GPP TS 26.141 6. The optimizations identified in the present document address mainly. media transport and signalling. Most of the SIP signalling is out of scope and is handled by other 3GPP groups. Issues regarding registration to the network and/or to IMS at power-on or at other occurr
31、ences are not included either. The optimization tools are not specified in the present document per se, but will be specified as amendments to existing (pre-Release 7) Technical Specifications (3GPP TS 26.235 3 and 3GPP TS 26.236 4) and possibly new Technical Specifications. Furthermore, a character
32、ization of the optimized multimedia telephony over IMS will be available in a separate Technical Report. 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
33、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. In the case of a reference to a 3GPP document (including a GSM document), a non-specific reference implici
34、tly refers to the latest version of that document in the same Release as the present document. 1 3GPP TR 21.905: “Vocabulary for 3GPP Specifications“. 2 3GPP TR 22.973: “IMS Multimedia Telephony Communication Enabler and supplementary services“. 3 3GPP TS 26.235: “Packet switched conversational mult
35、imedia applications; Default codecs“. 4 3GPP TS 26.236: “Packet switched conversational multimedia applications; Transport protocols“. 5 3GPP TR 26.935: “Packet Switched (PS) conversational multimedia applications; Performance characterization of default codecs“. 6 3GPP TS 26.141: “IP Multimedia Sys
36、tem (IMS) Messaging and Presence; Media formats and codecs“. 7 3GPP TS 43.318: “Generic access to the A/Gb interface; Stage 2“. 8 3GPP TR 45.912: “Feasibility study for evolved GSM/EDGE Radio Access Network (GERAN)“. ETSI ETSI TR 126 914 V15.0.0 (2018-07)63GPP TR 26.914 version 15.0.0 Release 159 IE
37、TF RFC 3550 (2003): “RTP: A Transport Protocol for Real-Time Applications“, H. Schulzrinne, S. Casner, R. Frederick and V. Jacobson. 10 IETF RFC 3551 (2003): “RTP Profile for Audio and Video Conferences with Minimal Control“, H. Schulzrinne and S. Casner. 11 IETF RFC 2327 (1998): “SDP: Session Descr
38、iption Protocol“, M. Handley M. and V. Jacobson. 12 3GPP TS 26.071: “AMR Speech Codec; General description“. 13 3GPP TS 26.090: “AMR Speech Codec; Transcoding functions“. 14 3GPP TS 26.073: “AMR Speech Codec; C-source code“. 15 3GPP TS 26.104: “ANSI-C code for the floating-point Adaptive Multi-Rate
39、(AMR) speech codec“. 16 3GPP TS 26.171: “AMR Speech Codec, wideband; General description“. 17 3GPP TS 26.190: “Speech codec speech processing functions; Adaptive Multi-Rate - Wideband (AMR-WB) speech codec; Transcoding functions“. 18 3GPP TS 26.173: “ANCI-C code for the Adaptive Multi Rate - Wideban
40、d (AMR-WB) speech codec“. 19 3GPP TS 26.204: “ANSI-C code for the floating-point Adaptive Multi-Rate Wideband (AMR-WB) speech codec“. 20 IETF RFC 3267 (2002): “Real-Time Transport Protocol (RTP) Payload Format and File Storage Format for the Adaptive Multi-Rate (AMR) Adaptive Multi-Rate Wideband (AM
41、R-WB) Audio Codecs“, J. Sjoberg, M. Westerlund, A. Lakaniemi and Q. Xie. 21 ITU-T Recommendation H.263 (1998): “Video coding for low bit rate communication“. 22 ITU-T Recommendation H.263 - Annex X (2004): “Profiles and levels definition“. 23 ISO/IEC 14496-2 (2004): “Information technology - Coding
42、of audio-visual objects - Part 2: Visual“. 24 ITU-T Recommendation H.264 (2005): “Advanced video coding for generic audiovisual services“ | ISO/IEC 14496-10:2005: “Information technology - Coding of audio-visual objects - Part 10: Advanced Video Coding“. 25 IETF RFC 3984 (2005): “RTP Payload Format
43、for H.264 Video“, S. Wenger, M.M. Hannuksela, T. Stockhammer, M. Westerlund and D. Singer. 26 3GPP TS 26.103: “Speech codec list for GSM and UMTS“. 27 IETF RFC 3095 (2001): “RObust Header Compression (ROHC): Framework and four profiles: RTP, UDP, ESP, and uncompressed“, C. Bormann and al. 28 3GPP TS
44、 26.234: “Transparent end-to-end Packet-switched Streaming Service (PSS); Protocols and codecs“. 3 Definitions and abbreviations 3.1 Definitions For the purposes of the present document, the following terms and definitions apply: example: text used to clarify abstract rules by applying them literall
45、y ETSI ETSI TR 126 914 V15.0.0 (2018-07)73GPP TR 26.914 version 15.0.0 Release 153.2 Abbreviations For the purposes of the present document, the abbreviations given in 3GPP TR 21.905 1 and the following apply: ARQ Automatic repeat ReQuest AS Application Server AVC Advanced Video Coding CSCF Call Ses
46、sion Control Function GAN Generic Access Network H-ARQ Hybrid - ARQ HSDPA High Speed Downlink Packet Access IMS IP Multimedia Subsystem IP Internet Protocol IPv4 Internet Protocol version 4 IPv6 Internet Protocol version 6 ITU-T International Telecommunications Union - Telecommunications MM MultiMed
47、ia MMS Multimedia Messaging Service QoS Quality of Service RTP Real-time Transport Protocol SDP Session Description Protocol SIP Session Initiation Protocol TBF Temporary Block Flow ToIP Telephony over IP TTI Transmission Time Interval URL Universal Resource Locator VoIP Voice over IP 4 Overview 4.1
48、 General The rest of the present document is divided into five main clauses. Clause 4 contains an architectural overview of the IMS system indicating the domain relevant to the work reported in the present document. Clause 5 provides the assumptions underlying the work of this report. General assump
49、tions refer to networks, codecs and backward compatibility, etc. The following subclauses give information relevant to the channels, media components as well as use scenarios for multimedia telephony that are relevant to the optimizations targeted by the present document. Clause 6 shows the current status in Release 6 for non-optimized multimedia telephony. The point-to-point voice call has been used as the basic “use case“. The goal for this use case is to show what is needed to create a VoIP telephony servic
