1、 ETSI TR 143 903 V15.0.0 (2018-07) Digital cellular telecommunications system (Phase 2+) (GSM); A-interface over IP study (AINTIP) (3GPP TR 43.903 version 15.0.0 Release 15) TECHNICAL REPORT GLOBAL SYSTEM FOR MOBILE COMMUNICATIONSRETSI ETSI TR 143 903 V15.0.0 (2018-07)13GPP TR 43.903 version 15.0.0
2、Release 15Reference RTR/TSGR-0643903vf00 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、 43.903 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 and non-members, and ca
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13、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 Generation Partnership Project (3GPP). The present document may refer to t
14、echnical 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, 3GPP and ETSI identities can be found under http:/webapp.etsi.org/key/quer
15、yform.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 “must not“ are NOT allo
16、wed in ETSI deliverables except when used in direct citation. ETSI ETSI TR 143 903 V15.0.0 (2018-07)33GPP TR 43.903 version 15.0.0 Release 15Contents Intellectual Property Rights 2g3Foreword . 2g3Modal verbs terminology 2g3Foreword . 5g3Introduction 5g31 Scope 6g32 References 6g33 Definitions, symbo
17、ls and abbreviations 7g33.1 Definitions 7g33.2 Symbols 8g33.3 Abbreviations . 8g34 Requirements 9g35 Overview 10g35.1 Background 10g35.2 Architecture 11g35.2.1 Legacy Architecture 11g35.2.2 PCM encoded speech (G.711) over IP 11g35.2.3 Compressed speech over IP 12g35.2.4 Example Deployment Scenarios
18、. 14g35.3 Functional Impacts . 18g35.3.1 G.711 and compressed speech over IP 18g35.3.2 Support for Data and Fax Services . 19g35.3.3 Functional Impacts for Migration . 19g36 Study Results, User Plane 19g36.1 User Plane Principles 19g36.1.1 Transport network User Plane for A over IP 19g36.1.1.1 PCM c
19、oded speech (G.711) over IP 19g36.1.1.2 Compressed speech and data/fax over IP 19g36.1.2 Transport network Control Plane for A over IP 20g36.1.3 Potential impact on the Nb and Nc interfaces . 20g36.2 Payload Formats . 20g36.2.1 Existing TRAU Frames for Speech 20g36.2.2 RTP profiles for speech 24g36.
20、2.2.1 RTP profiles for G.711 encoded speech on the A over IP interface 24g36.2.2.2 RTP profiles for compressed speech on the A over IP 24g36.2.2.3 RTP profiles for compressed speech on Nb interface . 24g36.2.3 RTP profiles for data and fax calls . 24g36.2.3.1 RTP profiles for data and fax calls with
21、 rate adaptation in BSS . 24g36.2.3.2 RTP profiles for data and fax calls with rate adaptation in CN . 25g36.3 Transport Layer 25g36.3.1 Link Layer and Physical Layer . 25g36.3.2 UDP and IP . 26g36.3.3 RTP . 26g36.3.4 RTCP 26g36.3.5 IP Multiplexing . 26g36.4 Handover Procedure (User Plane) 26g36.4.1
22、 Alternative 1 . 26g36.4.1.1 General Handover Procedure 26g36.4.1.2 Intra-BSC Handover to a compatible target cell . 26g36.4.1.3 Intra-BSC Handover to an incompatible target cell 26g36.4.1.4 Inter-BSC Handover 27g36.4.2 Alternative 2 . 27g36.5 Time Alignment . 27g3ETSI ETSI TR 143 903 V15.0.0 (2018-
23、07)43GPP TR 43.903 version 15.0.0 Release 156.5.1 Introduction. 27g36.5.2 Time Alignment principles . 27g36.5.3 Time Alignment performances evaluation 28g36.5.4 Proposed implementation . 30g36.5.5 Summary . 31g37 Study Results, Control Plane 32g37.1 Control Plane Principles . 32g37.1.1 Exchange of T
24、ransport Layer Information 32g37.1.2 Need for a Call Identifier for IP-based calls . 33g37.1.3 Exchange of Codec Information . 34g37.1.3.1 Exchange of Codec Information at Call Establishment 34g37.1.3.2 Exchange of Codec Information at Handover . 36g37.1.4 Location of Transcoder Resource in BSS or C
25、N 37g37.1.5 Exchange of RTP Parameters . 37g37.2 Signalling Messages . 39g37.2.1 BSSMAP 39g37.2.1.1 Assignment Request 39g37.2.1.2 Assignment Complete . 39g37.2.1.3 Handover Required . 40g37.2.1.4 Handover Request . 41g37.2.1.5 Handover Request Acknowledge 42g37.2.1.6 Handover Performed . 42g37.2.1.
26、7 Complete Layer 3 Information 43g37.2.1.8 BSC-SCL and MSC-PCL 43g37.2.1.9 Speech Codec (Chosen) 44g37.2.1.10 Speech Codec (Used) 44g37.2.1.11 Circuit Switched Data Codec (CSD Dummy Codec) 44g37.2.2 DTAP 45g37.2.3 VGCS/VBS Protocol 45g37.2.4 H.248 Protocol 45g37.3 Procedures 45g37.3.1 Codec Negotiat
27、ion at Call Setup . 45g37.3.2 Codec Negotiation at Handover 47g37.3.2.1 Intra-BSC Handover to a Compatible Target Cell 48g37.3.2.2 Intra-BSC Handover to an Incompatible Target Cell 48g37.3.2.3 Inter-BSC Handover 51g37.3.3 Codec Re-Negotiation after Inter-BSC Handover 53g37.4 Impacts on the A Interfa
28、ce Control Plane 55g37.4.1 New Information Element: BSC-SCL 55g37.4.2 New Information Element: MSC-PCL . 56g37.4.3 New Information Element: Speech Codec (Chosen) 58g37.4.4 New Information Element: Speech Codec (Used) 58g38 Informative: Network Design Issues 59g38.1 Solution 1 . 59g38.2 Solution 2 .
29、59g39 Expected impacts to existing specifications . 59g310 Summary and Conclusion 59g3Annex A (informative): Change history . 61g3History 62g3ETSI ETSI TR 143 903 V15.0.0 (2018-07)53GPP TR 43.903 version 15.0.0 Release 15Foreword This Technical Report has been produced by the 3rdGeneration Partnersh
30、ip Project (3GPP). 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 re-released by the TSG with an identifying change of release date and an increase
31、 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 digit is incremented for all changes of substance, i.e. technical enhancements,
32、corrections, updates, etc. z the third digit is incremented when editorial only changes have been incorporated in the document. Introduction The present document captures the results of the feasibility study for introducing support for A-interface over IP. ETSI ETSI TR 143 903 V15.0.0 (2018-07)63GPP
33、 TR 43.903 version 15.0.0 Release 151 Scope The present document contains the result from the study of introduction of support for A-interface 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-interfac
34、e, impact on call related messages, payload formats. The following items shall be covered in the study: - In the target solution it is 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
35、 kind of transcoders shall be studied, and the architecture might place Codecs in the core network. - Impacts/changes on current 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 procedure
36、s. - In addition to allow compressed speech over the A-interface the study shall provide further solution for effective bandwidth 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. - The study shall de
37、scribe a solution for “true end-to-end Codec negotiation“, which considers on a call basis the preference/situation of the radio network. - It shall be studied how call related messages have to be adapted, e.g. transfer of Codec related information, identification of calls/sessions. - The study shal
38、l describe the wanted payload formats and other relevant user plane parameters like packetization time etc. 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 da
39、te 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 impl
40、icitly 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 TS 23.205: “Bearer-independent circuit-switched core network“. 3 3GPP TS 25.415: “UTRAN Iu Interface User Plane Protocols“. 4 3GPP TS 48.00
41、6: “Signaling Transport Mechanism Specification for the Base Station System -Mobile-services Switching Centre (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 3
42、GPP TS 48.060: “In-band control for remote transcoders and rate adaptors for full rate traffic channels“. 8 3GPP 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
43、- (G)MSC-S Nc Interface based on the SIP-I protocol“. ETSI ETSI TR 143 903 V15.0.0 (2018-07)73GPP TR 43.903 version 15.0.0 Release 1511 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
44、 Nb data transport and transport signalling“. 14 3GPP TS 25.415: “UTRAN Iu interface user plane protocols“. 15 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:
45、“Mandatory speech codec speech processing functions Adaptive Multi-Rate (AMR) speech codec; Source controlled 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 76
46、8: “User Datagram Protocol“. 21 IETF RFC 791: “Internet Protocol“. 22 IETF RFC 792: “Internet Control Message 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) Spe
47、cification“. 25 IETF RFC 4867: “RTP Payload Format and File Storage Format for the Adaptive Multi-Rate (AMR) and 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
48、TR 21.905 1 and the following apply. A term defined in the present document takes precedence over the definition 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:
49、Legacy MSC Server: The Legacy MSC server does not support AoIP. Legacy MGW: The Legacy MGW does not support AoIP. 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 interfaces could work simultaneously for different BSSs. It is claimed by some companies (e.g. Ericsson) that it is necessary
