1、 ETSI TR 143 903 V14.0.0 (2017-04) Digital cellular telecommunications system (Phase 2+) (GSM); A-interface over IP study (AINTIP) (3GPP TR 43.903 version 14.0.0 Release 14) TECHNICAL REPORT GLOBAL SYSTEM FOR MOBILE COMMUNICATIONSRETSI ETSI TR 143 903 V14.0.0 (2017-04)13GPP TR 43.903 version 14.0.0
2、Release 14Reference RTR/TSGR-0643903ve00 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 (06) N 7803/88 Important
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9、TSI ETSI TR 143 903 V14.0.0 (2017-04)23GPP TR 43.903 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 member
10、s 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 available on the ETSI Web server (https:/ipr.etsi.o
11、rg/). 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 are, or may be, or may become, essential to the p
12、resent document. Foreword This Technical 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 referen
13、ces 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 “should“, “should not“, “may“, “need not“, “will“, “will not“, “can“ and “cannot“ ar
14、e 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 citation. ETSI ETSI TR 143 903 V14.0.0 (2017-04)33GPP TR 43.903 version 14.0.0 Release 14Co
15、ntents Intellectual Property Rights 2g3Foreword . 2g3Modal verbs terminology 2g3Foreword . 5g3Introduction 5g31 Scope 6g32 References 6g33 Definitions, symbols and abbreviations 7g33.1 Definitions 7g33.2 Symbols 8g33.3 Abbreviations . 9g34 Requirements 9g35 Overview 10g35.1 Background 10g35.2 Archit
16、ecture 11g35.2.1 Legacy Architecture 11g35.2.2 PCM encoded speech (G.711) over IP 12g35.2.3 Compressed speech over IP 13g35.2.4 Example Deployment Scenarios . 15g35.3 Functional Impacts . 19g35.3.1 G.711 and compressed speech over IP 19g35.3.2 Support for Data and Fax Services . 20g35.3.3 Functional
17、 Impacts for Migration . 20g36 Study Results, User Plane 20g36.1 User Plane Principles 20g36.1.1 Transport network User Plane for A over IP 20g36.1.1.1 PCM coded speech (G.711) over IP 20g36.1.1.2 Compressed speech and data/fax over IP 21g36.1.2 Transport network Control Plane for A over IP 21g36.1.
18、3 Potential impact on the Nb and Nc interfaces . 21g36.2 Payload Formats . 21g36.2.1 Existing TRAU Frames for Speech 21g36.2.2 RTP profiles for speech 25g36.2.2.1 RTP profiles for G.711 encoded speech on the A over IP interface 25g36.2.2.2 RTP profiles for compressed speech on the A over IP 25g36.2.
19、2.3 RTP profiles for compressed speech on Nb interface . 26g36.2.3 RTP profiles for data and fax calls . 26g36.2.3.1 RTP profiles for data and fax calls with rate adaptation in BSS . 26g36.2.3.2 RTP profiles for data and fax calls with rate adaptation in CN . 26g36.3 Transport Layer 27g36.3.1 Link L
20、ayer and Physical Layer . 27g36.3.2 UDP and IP . 27g36.3.3 RTP . 27g36.3.4 RTCP 27g36.3.5 IP Multiplexing . 27g36.4 Handover Procedure (User Plane) 28g36.4.1 Alternative 1 . 28g36.4.1.1 General Handover Procedure 28g36.4.1.2 Intra-BSC Handover to a compatible target cell . 28g36.4.1.3 Intra-BSC Hand
21、over to an incompatible target cell 28g36.4.1.4 Inter-BSC Handover 28g36.4.2 Alternative 2 . 28g3ETSI ETSI TR 143 903 V14.0.0 (2017-04)43GPP TR 43.903 version 14.0.0 Release 146.5 Time Alignment . 28g36.5.1 Introduction. 28g36.5.2 Time Alignment principles . 29g36.5.3 Time Alignment performances eva
22、luation 30g36.5.4 Proposed implementation . 31g36.5.5 Summary . 32g37 Study Results, Control Plane 33g37.1 Control Plane Principles . 33g37.1.1 Exchange of Transport Layer Information . 33g37.1.2 Need for a Call Identifier for IP-based calls . 34g37.1.3 Exchange of Codec Information . 35g37.1.3.1 Ex
23、change of Codec Information at Call Establishment 35g37.1.3.2 Exchange of Codec Information at Handover . 37g37.1.4 Location of Transcoder Resource in BSS or CN 38g37.1.5 Exchange of RTP Parameters . 38g37.2 Signalling Messages . 40g37.2.1 BSSMAP 40g37.2.1.1 Assignment Request 40g37.2.1.2 Assignment
24、 Complete . 40g37.2.1.3 Handover Required . 41g37.2.1.4 Handover Request . 42g37.2.1.5 Handover Request Acknowledge 43g37.2.1.6 Handover Performed . 43g37.2.1.7 Complete Layer 3 Information 44g37.2.1.8 BSC-SCL and MSC-PCL 44g37.2.1.9 Speech Codec (Chosen) 45g37.2.1.10 Speech Codec (Used) 45g37.2.1.1
25、1 Circuit Switched Data Codec (CSD Dummy Codec) 45g37.2.2 DTAP 46g37.2.3 VGCS/VBS Protocol 46g37.2.4 H.248 Protocol 46g37.3 Procedures 46g37.3.1 Codec Negotiation at Call Setup . 46g37.3.2 Codec Negotiation at Handover 48g37.3.2.1 Intra-BSC Handover to a Compatible Target Cell 49g37.3.2.2 Intra-BSC
26、Handover to an Incompatible Target Cell 49g37.3.2.3 Inter-BSC Handover 52g37.3.3 Codec Re-Negotiation after Inter-BSC Handover 54g37.4 Impacts on the A Interface Control Plane 56g37.4.1 New Information Element: BSC-SCL 56g37.4.2 New Information Element: MSC-PCL . 58g37.4.3 New Information Element: S
27、peech Codec (Chosen) 59g37.4.4 New Information Element: Speech Codec (Used) 59g38 Informative: Network Design Issues 60g38.1 Solution 1 . 60g38.2 Solution 2 . 60g39 Expected impacts to existing specifications . 60g310 Summary and Conclusion 60g3Annex A (informative): Change history . 62g3History 63g
28、3ETSI ETSI TR 143 903 V14.0.0 (2017-04)53GPP TR 43.903 version 14.0.0 Release 14Foreword 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 following formal TSG app
29、roval. 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 TSG for approval; 3
30、 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 document. Introduction
31、The present document captures the results of the feasibility study for introducing support for A-interface over IP. ETSI ETSI TR 143 903 V14.0.0 (2017-04)63GPP TR 43.903 version 14.0.0 Release 141 Scope The present document contains the result from the study of introduction of support for A-interfac
32、e over IP. High level areas that are studied are e.g. potential placement of transcoders in the core network, effective bandwidth utilisation at the A-interface, impact on call related messages, payload formats. The following items shall be covered in the study: square4 In the target solution it is
33、wanted to transfer compressed speech as far as possible end-to-end to achieve efficient transport and speech quality. The possibility to free GERAN from handling all kind of transcoders shall be studied, and the architecture might place Codecs in the core network. square4 Impacts/changes on current
34、A-interface procedures resulting from placing transcoders in the core network as well as in the BSS shall be studied, e.g. impacts on the assignment and handover procedures. square4 In addition to allow compressed speech over the A-interface the study shall provide further solution for effective ban
35、dwidth utilisation at the A interface, which means it shall describe multiplexing of RTP flows and how this will be negotiated between the BSS and CN nodes. square4 The study shall describe a solution for “true end-to-end Codec negotiation“, which considers on a call basis the preference/situation o
36、f the radio network. square4 It shall be studied how call related messages have to be adapted, e.g. transfer of Codec related information, identification of calls/sessions. square4 The study shall describe the wanted payload formats and other relevant user plane parameters like packetization time et
37、c. 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. For a specific reference, subsequ
38、ent 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 present document. 1 3GPP TR 21.
39、905: “Vocabulary for 3GPP Specifications“. 2 3GPP TS 23.205: “Bearer-independent circuit-switched core network“. 3 3GPP TS 25.415: “UTRAN Iu Interface User Plane Protocols“. 4 3GPP TS 48.006: “Signaling Transport Mechanism Specification for the Base Station System - Mobile-services Switching Centre
40、(BSS - MSC) Interface“. 5 3GPP TS 23.002: “Network architecture (Release 8)“. 6 3GPP TS 48.008: “Mobile Switching Centre - Base Station System (MSC-BSS) interface Layer 3 specification“. 7 3GPP TS 48.060: “In-band control for remote transcoders and rate adaptors for full rate traffic channels“. 8 3G
41、PP TS 48.061: “In-band control for remote transcoders and rate adaptors for half rate traffic channels“. 9 3GPP TS 26.103: “Speech Codec list for GSM and UMTS“. 10 3GPP TS 29.802: “(G)MSC-S - (G)MSC-S Nc Interface based on the SIP-I protocol“. ETSI ETSI TR 143 903 V14.0.0 (2017-04)73GPP TR 43.903 ve
42、rsion 14.0.0 Release 1411 3GPP TS 23.153: “Out of band transcoder control; Stage 2“. 12 3GPP TS 23.231: “SIP-I based circuit-switched core network; Stage 2“. 13 3GPP TS 29.414: “Core network Nb data transport and transport signalling“. 14 3GPP TS 25.415: “UTRAN Iu interface user plane protocols“. 15
43、 3GPP TS 29.415: “Core Network Nb Interface User Plane Protocols“. 16 3GPP TS 28.062: “Inband Tandem Free Operation (TFO) of speech codecs; Service description; Stage 3“. 17 3GPP TS 26.093: “Mandatory speech codec speech processing functions Adaptive Multi-Rate (AMR) speech codec; Source controlled
44、rate operation“. 18 IETF RFC 4040: “RTP Payload Format for a 64 kbit/s Transparent Call“. 19 IETF RFC 3551: “RTP Profile for Audio and Video Conferences with Minimal Control“. 20 IETF RFC 768: “User Datagram Protocol“. 21 IETF RFC 791: “Internet Protocol“. 22 IETF RFC 792: “Internet Control Message
45、Protocol“. 23 IETF RFC 2460: “Internet Protocol, Version 6 (IPv6) Specification“. 24 IETF RFC 4443: “Internet Control Message Protocol (ICMPv6) for the Internet Protocol Version 6 (IPv6) Specification“. 25 IETF RFC 4867: “RTP Payload Format and File Storage Format for the Adaptive Multi-Rate (AMR) a
46、nd Adaptive Multi-Rate Wideband (AMR-WB) Audio Codecs“. 3 Definitions, symbols and abbreviations 3.1 Definitions For the purposes of the present document, the terms and definitions given in TR 21.905 1 and the following apply. A term defined in the present document takes precedence over the definiti
47、on of the same term, if any, in TR 21.905 1. example: text used to clarify abstract rules by applying them literally. For the sake of easy explanation the following short terms are defined: Legacy MSC Server: The Legacy MSC server does not support AoIP. Legacy MGW: The Legacy MGW does not support Ao
48、IP. Legacy BSS: The Legacy BSS does not support AoIP. New MSC Server: The New MSC Server supports only the AoIP-interface. Legacy BSSes are not supported by a New MSC Server. Upgraded MSC Server: The Upgraded MSC Server supports both, the TDM A-interface and the IP A-interface. Both kinds of interfa
49、ces could work simultaneously for different BSSs. It is claimed by some companies (e.g. Ericsson) that it is necessary to support AoTDM and AoIP also for the same, Upgraded BSS. Also legacy BSS, i.e. without any change, is supported by an Upgraded MSC Server. ETSI ETSI TR 143 903 V14.0.0 (2017-04)83GPP TR 43.903 version 14.0.0 Release 14New MGW: The New MGW supports all UMTS and GSM Codecs as specified in 3GPP TS 26.103 18 and has only an IP interface towards the BSS. The New MGW does not support AoTDM, not TFO and
