1、 ETSI TR 103 279 V1.1.1 (2014-08) End to End Network Architectures (E2NA); Location of Transcoders for voice and video communications TECHNICAL REPORT ETSI ETSI TR 103 279 V1.1.1 (2014-08) 2Reference DTR/E2NA-00006-Loc-Transcoders Keywords codec, interconnection, transcoding ETSI 650 Route des Lucio
2、les 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 notice The present document can be downloaded from: http:/www.etsi.org The pre
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5、urrent status of this and other ETSI documents is available at http:/portal.etsi.org/tb/status/status.asp If you find errors in the present document, please send your comment to one of the following services: http:/portal.etsi.org/chaircor/ETSI_support.asp Copyright Notification No part may be repro
6、duced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm except as authorized by written permission of ETSI. The content of the PDF version shall not be modified without the written authorization of ETSI. The copyright and the foregoing restrictio
7、n extend to reproduction in all media. European Telecommunications Standards Institute 2014. All rights reserved. DECTTM, PLUGTESTSTM, UMTSTMand the ETSI logo are Trade Marks of ETSI registered for the benefit of its Members. 3GPPTM and LTE are Trade Marks of ETSI registered for the benefit of its M
8、embers and of the 3GPP Organizational Partners. GSM and the GSM logo are Trade Marks registered and owned by the GSM Association. ETSI ETSI TR 103 279 V1.1.1 (2014-08) 3Contents Intellectual Property Rights 4g3Foreword . 4g3Modal verbs terminology 4g3Introduction 4g31 Scope 5g32 References 5g32.1 No
9、rmative references . 5g32.2 Informative references 5g33 Definitions and abbreviations . 5g33.1 Definitions 5g33.2 Abbreviations . 6g34 Background 6g35 Review of standards and technical specifications 6g35.1 Interconnection between service provider networks 6g35.1.1 Interconnection between circuit-sw
10、itched networks . 6g35.1.1.1 Direct interconnection between fixed service provider networks . 6g35.1.1.2 Direct interconnection between mobile service provider networks 7g35.1.1.3 Direct interconnection between a fixed and a mobile service provider network . 7g35.1.1.4 Non-direct interconnection bet
11、ween service provider networks . 7g35.1.2 Interconnection between a circuit-switched service provider network and an IP-based service provider network . 7g35.1.2.1 Direct interconnection between fixed service provider networks . 7g35.1.2.2 Direct interconnection between mobile service provider netwo
12、rks 7g35.1.2.3 Direct interconnection between a fixed and a mobile service provider network . 7g35.1.2.4 Non-direct interconnection between service provider networks . 7g35.1.3 Interconnection between IP-based service provider networks 8g35.1.3.1 Direct interconnection . 8g35.1.3.2 Non-direct interc
13、onnection 8g35.2 Location of transcoders inside networks 8g35.2.1 Circuit-switched service provider networks . 8g35.2.1.1 Fixed networks 8g35.2.1.2 Mobile Networks. 8g35.2.2 VoIP service provider networks 9g35.2.2.1 IMS . 9g35.2.2.2 Other networks 9g36 Gap Analysis 9g37 Recommendations 9g37.1 Guidan
14、ce for service providers . 9g37.2 Suggested additions to existing standards 10g3History 11g3ETSI ETSI TR 103 279 V1.1.1 (2014-08) 4Intellectual Property Rights IPRs essential or potentially essential to the present document may have been declared to ETSI. The information pertaining to these essentia
15、l IPRs, 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 ar
16、e available on the ETSI Web server (http:/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) whic
17、h are, or may be, or may become, essential to the present document. Foreword This Technical Report (TR) has been produced by ETSI Project End-to-End Network Architectures (E2NA). Modal verbs terminology In the present document “shall“, “shall not“, “should“, “should not“, “may“, “may not“, “need“, “
18、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 allowed in ETSI deliverables except when used in direct citation. Introduction As the number of
19、 voice and video codecs available on the market place increases, resorting to transcoding functions becomes unavoidable. There seems to be little guidance on where to implement and invoke these functions within and between networks. Which network (e.g. the originating, transit or terminating network
20、, the fixed or the mobile network) should be responsible for transcoding and which entity inside this network (e.g. home gateway, edge gateway, border gateway, trunking gateway, specialized media gateway in the core network, etc.) should perform transcoding are typical questions that have to be answ
21、ered to ensure successful call setup procedures with optimal end-to-end quality of experience. ETSI ETSI TR 103 279 V1.1.1 (2014-08) 51 Scope The present document provides a review of standardization activities on the location of transcoders for voice and video communications inside and across netwo
22、rks. It identifies issues that are not addressed in current standards and provides recommendations to fill these gaps. 2 References References are either specific (identified by date of publication and/or edition number or version number) or non-specific. For specific references, only the cited vers
23、ion applies. For non-specific references, the latest version of the referenced document (including any amendments) applies. Referenced documents which are not found to be publicly available in the expected location might be found at http:/docbox.etsi.org/Reference. NOTE: While any hyperlinks include
24、d in this clause were valid at the time of publication ETSI cannot guarantee their long term validity. 2.1 Normative references The following referenced documents are necessary for the application of the present document. Not applicable. 2.2 Informative references The following referenced documents
25、are not necessary for the application of the present document but they assist the user with regard to a particular subject area. i.1 GSMATMIN.24: “Voice IPX break in - out interworking scenarios recommendation on IPX Hubbing Quality“, Version 1.1, 12thFebruary 2013. i.2 i3 forum document: “Voice pat
26、h engineering in international IP-based networks“, Release 3, May 2011. i.3 ETSI TS 123 228: “Digital cellular telecommunications system (Phase 2+); Universal Mobile Telecommunications System (UMTS); LTE; IP Multimedia Subsystem (IMS); Stage 2 (3GPP TS 23.228)“. i.4 ETSI TS 123 153: “Digital cellula
27、r telecommunications system (Phase 2+); Universal Mobile Telecommunications System (UMTS); LTE; Out of band transcoder control; Stage 2 (3GPP TS 23.153)“. 3 Definitions and abbreviations 3.1 Definitions For the purposes of the present document, the following terms and definitions apply: direct inter
28、connection: interconnection without intermediate networks between two service providers networks non direct interconnection: interconnection with a least one intermediate network between service providers networks service provider: specific type of application service provider that provides voice re
29、lated services and optionally text and video-related services ETSI ETSI TR 103 279 V1.1.1 (2014-08) 63.2 Abbreviations For the purposes of the present document, the following abbreviations apply: AMR-WB Adaptive Multi Rate - WideBand ATM Asynchronous Transfer Mode CN Core Network CS Circuit Switched
30、CSCF Call Service Control Function GSMATMGlobal System for Mobile communications Association HD High DefinitionIBCF Interconnect Border Control Function IMS IP Multimedia Subsystem IP Internet Protocol IPX IP eXchangeITU-T International Telecommunication Union Telecommunication Standardization Secto
31、r MRFC Multimedia Resource Function Controller MSC Mobile services Switching Centre PCM Pulse Code Modulation P-CSCF Proxy CSCF SA System Architecture (Technical Specification Group of 3GPP) STQ ETSI technical committee for Speech, Transmission planning, and Quality of service TDM Time Division Mult
32、iplexing TTC Telecommunications Technology Committee (Japan) UE User Equipment UMTS Universal Mobile Telecommunications System 4 Background The review performed in the present document is a based on an analysis of standards and technical specifications from the following organizations and liaisons s
33、tatements received from these organizations: 3GPP SA ETSI STQ GSMATMIWG/IMQ i3 forum ITU-T SG16 TTC Media Coding 5 Review of standards and technical specifications 5.1 Interconnection between service provider networks 5.1.1 Interconnection between circuit-switched networks 5.1.1.1 Direct interconnec
34、tion between fixed service provider networks The present document has not identified any publicly available standards or technical specification providing guidelines on the location of transcoders for this configuration. ETSI ETSI TR 103 279 V1.1.1 (2014-08) 75.1.1.2 Direct interconnection between m
35、obile service provider networks According to ETSI TS 123 153 i.4, where no compatible codec type can be selected between the UEs then the default PCM coding is expected to be selected. The originating MSC is expected to insert a transcoder in the path from the originating UE. Codec selection for the
36、 terminating UE is then performed within the terminating MSC, independently of the originating MSC. In configurations where one service provider uses ATM or IP transport (i.e. bearer-independent CS core network) and the other service provider uses TDM transport, the capability to insert transcoder a
37、 (in cases where transcoder free operation is not possible) at the most appropriate location (i.e. to save bandwidth), should be located at the CN edge between an ATM or IP transport network and a TDM network. 5.1.1.3 Direct interconnection between a fixed and a mobile service provider network The p
38、resent document has not identified any publicly available standards or technical specification providing guidelines on the location of transcoders for this configuration. 5.1.1.4 Non-direct interconnection between service provider networks The present document has not identified any publicly availab
39、le standards or technical specification providing guidelines on the location of transcoders for this configuration. 5.1.2 Interconnection between a circuit-switched service provider network and an IP-based service provider network 5.1.2.1 Direct interconnection between fixed service provider network
40、s The present document has not identified any publicly available standards or technical specification providing guidelines on the location of transcoders for this configuration. 5.1.2.2 Direct interconnection between mobile service provider networks The present document has not identified any public
41、ly available standards or technical specification providing guidelines on the location of transcoders for this configuration. 5.1.2.3 Direct interconnection between a fixed and a mobile service provider network The present document has not identified any publicly available standards or technical spe
42、cification providing guidelines on the location of transcoders for this configuration. 5.1.2.4 Non-direct interconnection between service provider networks According to the i3 forum i.2, in general, intermediate networks are transparent and do not perform transcoding but, if under specific condition
43、s and/or commercial agreement they are requested to transcode, this function usually takes place in different locations: a) for the A-law/m-law conversion transcoding is performed by the m-law carrier; b) in case of conversion from IP to TDM transcoding is performed by the media gateway before passi
44、ng the media to the TDM carrier; c) in other cases, many different cases could be described depending on the architecture and network capabilities of the Service Providers and Carriers involved in the end-to-end communication. According to i.2, if the call is to be routed to a TDM network and if the
45、 originating terminal does not support G.711 interconnection, the carrier interconnecting to the TDM network is expected to perform transcoding. ETSI ETSI TR 103 279 V1.1.1 (2014-08) 85.1.3 Interconnection between IP-based service provider networks 5.1.3.1 Direct interconnection For IMS, there are n
46、o defined end to end mechanisms to determine the location of transcoding functions since there are many factors which would affect such decision which include specific call scenarios, network deployment, business agreement between operators and mobility cases. 5.1.3.2 Non-direct interconnection Acco
47、rding to the i3 forum i.2, in general, intermediate networks are transparent and do not perform transcoding but, if under specific conditions and/or commercial agreement they are requested to transcode, this function usually takes place in different locations: for the A-law/m-law conversion transcod
48、ing is performed by the m-law carrier; in other cases, many different cases could be described depending on the architecture and network capabilities of the Service Providers and Carriers involved in the end-to-end communication. According to GSMA i.1, only if no coincidences are met between the ser
49、vice providers codec lists, transcoding will be performed by the IPX Hub. This only will apply to break in/out scenarios: 1) IPXP1 and IPXP2 will negotiate on bilateral basis that will perform the transcoding when needed. 2) For all obligations described in the different scenarios, the cascading responsibility applies. In case the IPXP1 relies on the services of IPXP2 in regards to the IPX break in/out functionalities, IPXP1 needs to ensure that a proper contract with the IPXP2 is in place in order for IPXP1 to be able to make a commitme
