1、 INTERNATIONAL TELECOMMUNICATION UNION ITU-T G.769/Y.1242TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (06/2004) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS Digital terminal equipments Principal characteristics of transcoder and digital multiplication equipment SERIES Y:
2、 GLOBAL INFORMATION INFRASTRUCTURE, INTERNET PROTOCOL ASPECTS AND NEXT GENERATION NETWORKS Internet protocol aspects Architecture, access, network capabilities and resource management Circuit multiplication equipment optimized for IP-based networks ITU-T Recommendation G.769/Y.1242 ITU-T G-SERIES RE
3、COMMENDATIONS TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS G.100G.199 GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS G.200G.299 INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METAL
4、LIC LINES G.300G.399 GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES G.400G.449 COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY G.450G.499 TESTING EQUIPMENTS G.500G.599 TRANSMISSION MEDIA CHARACTERISTICS G
5、.600G.699 DIGITAL TERMINAL EQUIPMENTS G.700G.799 General G.700G.709 Coding of analogue signals by pulse code modulation G.710G.719 Coding of analogue signals by methods other than PCM G.720G.729 Principal characteristics of primary multiplex equipment G.730G.739 Principal characteristics of second o
6、rder multiplex equipment G.740G.749 Principal characteristics of higher order multiplex equipment G.750G.759 Principal characteristics of transcoder and digital multiplication equipment G.760G.769 Operations, administration and maintenance features of transmission equipment G.770G.779 Principal char
7、acteristics of multiplexing equipment for the synchronous digital hierarchy G.780G.789 Other terminal equipment G.790G.799 DIGITAL NETWORKS G.800G.899 DIGITAL SECTIONS AND DIGITAL LINE SYSTEM G.900G.999 QUALITY OF SERVICE AND PERFORMANCE - GENERIC AND USER-RELATED ASPECTS G.1000G.1999 TRANSMISSION M
8、EDIA CHARACTERISTICS G.6000G.6999 DIGITAL TERMINAL EQUIPMENTS G.7000G.7999 DIGITAL NETWORKS G.8000G.8999 For further details, please refer to the list of ITU-T Recommendations. ITU-T Rec. G.769/Y.1242 (06/2004) i ITU-T Recommendation G.769/Y.1242 Circuit multiplication equipment optimized for IP-bas
9、ed networks Summary This Recommendation contains principles and examples of multiplication schemes of voice, facsimile and voiceband data between the International Switching Centre (ISC) (exchanges) which are connected via IP-based networks. Source ITU-T Recommendation G.769/Y.1242 was approved on 1
10、3 June 2004 by ITU-T Study Group 15 (2001-2004) under the ITU-T Recommendation A.8 procedure. ii ITU-T Rec. G.769/Y.1242 (06/2004) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications. The ITU Telecommunication Standardi
11、zation Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Assembly (WTSA), which
12、meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. In some areas of information technology which fall within ITU-
13、Ts purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. NOTE In this Recommendation, the expression “Administration“ is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. Compliance with this Recommendation
14、is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure e.g. interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words “shall“ or some other obligatory language such as “must“
15、and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. INTELLECTUAL PROPERTY RIGHTS ITU draws attention to the possibility that the practice or implementation of this Recommendation may i
16、nvolve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. As of the date of approval of this R
17、ecommendation, ITU had received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementors are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database. I
18、TU 2004 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. ITU-T Rec. G.769/Y.1242 (06/2004) iii CONTENTS Page 1 Scope 1 2 Normative references 1 3 Definitions 3 4 Abbreviations 4 5 Target services to be supported
19、 5 6 Network reference model . 5 6.1 Connection configuration . 5 6.2 Interfaces 6 7 Functions of the IP-CME 7 7.1 Packetized transmission modes and their functions related to stream handling function 7 7.2 Trunk I/F access function . 9 7.3 ISC signalling I/F control function. 9 7.4 IP transmission
20、channel I/F access function. 10 7.5 Packetized IP-CME control signalling function. 11 7.6 Transport of call control signalling function 12 7.7 Multiplexing function. 12 7.8 Application transmission function 15 7.9 Multiplexing load control function. 15 7.10 System operation management function 16 7.
21、11 QoS policy management function 16 7.12 Network management function 16 8 Structure of the multiplexed packet 16 8.1 PL indicator bit (X) 17 8.2 Payload Length (PL). 17 8.3 IPP-ID indicator bit (Y) 17 8.4 IP port ID (IPP-ID). 17 Annex A IP transmission channel control procedure for packetized trans
22、mission mode A . 18 A.1 Conditions. 18 A.2 Parameters 18 A.3 Procedure 20 Annex B IP transmission channel control procedure for packetized transmission mode B 23 B.1 Introduction 23 B.2 Approach 23 B.3 Multiplexing structure 24 B.4 Short packet format for typical applications (details are for furthe
23、r study) . 25 iv ITU-T Rec. G.769/Y.1242 (06/2004) Page Appendix I Functional architecture. 27 I.1 Functional implementation. 27 ITU-T Rec. G.769/Y.1242 (06/2004) 1 ITU-T Recommendation G.769/Y.1242 Circuit multiplication equipment optimized for IP-based networks 1 Scope This Recommendation contains
24、 principles and examples of multiplication schemes of voice, facsimile and voiceband data between the International Switching Centre (ISC) (exchanges) (see Note) which are connected via IP-based networks. Circuit multiplication equipment may have integral echo control and A/-law converter functions.
25、 The information in this Recommendation is compatible with the control procedures for such devices. NOTE As circuit multiplication equipment may also be used in national networks, the signalling described here could not only be used in International switching centres but also in national exchanges.
26、This Recommendation applies to digital circuit multiplication equipment optimized for IP-based networks (IP-CME) and specifies the following aspects for IP-CME in order to achieve interworking between them. a) Network interface requirements connection configuration; trunk and bearer facility interfa
27、ce; IP-based networks interface; call control signalling; IP-CME control signalling which includes definition of coding types; echo control. b) Functional requirements multiplication schemes optimized for IP-based networks; handling of the call signalling transmission between the ISCs; handling of t
28、he IP-CME control signalling between IP-CMEs; multiplexing load control of IP-transmission channels over IP-based networks; dynamic load control of calls in PSTN side; network management; management of voice, facsimile and voiceband data quality transported over IP-based networks; system operation (
29、capacity, overload strategy, maintenance, alarm). c) Performance criteria of IP-CME system elements speech detector; facsimile detector; voiceband data detector; signalling detector. 2 Normative references The following ITU-T Recommendations and other references contain provisions which, through ref
30、erence in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; 2 ITU-T Rec. G.769/Y.1242 (06/2004) users of this Recommendation are therefore encouraged to investigate
31、 the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of
32、 a Recommendation. ITU-T Recommendation G.109 (1999), Definition of categories of speech transmission quality. ITU-T Recommendation G.168 (2004), Digital network echo cancellers. ITU-T Recommendation G.177 (1999), Transmission planning for voiceband services over hybrid Internet/PSTN connections. IT
33、U-T Recommendation G.701 (1993), Vocabulary of digital transmission and multiplexing and pulse code modulation (PCM) terms. ITU-T Recommendation G.703 (2001), Physical/electrical characteristics of hierarchical digital interfaces. ITU-T Recommendation G.704 (1998), Synchronous frame structures used
34、at 1544, 6312, 2048, 8448 and 44 736 kbit/s hierarchical levels. ITU-T Recommendation G.711 (1988), Pulse code modulation (PCM) of voice frequencies. ITU-T Recommendation G.711 Appendix I (1999), A high quality low-complexity algorithm for packet loss concealment with G.711. ITU-T Recommendation G.7
35、11 Appendix II (2000), A comfort noise payload definition for ITU-T G.711 use in packet-based multimedia communication systems. ITU-T Recommendation G.723.1 (1996), Speech coders: Dual rate speech coder for multimedia communications transmitting at 5.3 and 6.3 kbit/s. ITU-T Recommendation G.723.1 An
36、nex A (1996), Silence compression scheme. ITU-T Recommendation G.726 (1990), 40, 32, 24, 16 kbit/s Adaptive Differential Pulse Code Modulation (ADPCM). ITU-T Recommendation G.729 (1996), Coding of speech at 8 kbit/s using conjugate-structure algebraic-code-excited linear prediction (CS-ACELP). ITU-T
37、 Recommendation G.729 Annex B (1996), A silence compression scheme for G.729 optimized for terminals conforming to Recommendation V.70. ITU-T Recommendation G.763 (1998), Digital circuit multiplication equipment using G.726 ADPCM and digital speech interpolation. ITU-T Recommendation G.957 (1999), O
38、ptical interfaces for equipments and systems relating to the synchronous digital hierarchy. ITU-T Recommendations I.233.x (1991), Frame mode bearer services. ITU-T Recommendation I.363.1 (1996), B-ISDN ATM Adaptation Layer specification: Type 1 AAL. ITU-T Recommendation I.363.2 (2000), B-ISDN ATM Ad
39、aptation Layer specification: Type 2 AAL. ITU-T Recommendation I.363.5 (1996), B-ISDN ATM Adaptation Layer specification: Type 5 AAL. ITU-T Recommendation P.862 (2001), Perceptual evaluation of speech quality (PESQ): An objective method for end-to-end speech quality assessment of narrow-band telepho
40、ne networks and speech codecs. ITU-T Rec. G.769/Y.1242 (06/2004) 3 ITU-T Recommendation Q.2 (1988), Signal receivers for automatic and semi-automatic working, used for manual working. ITU-T Recommendation Q.50 (2001), Signalling between Circuit Multiplication Equipment (CME) and International Switch
41、ing Centres (ISC). ITU-T Recommendation Q.50.1 (2001), Signalling between International Switching Centres (ISC) and Digital Circuit Multiplication Equipment (DCME) including the control of compression/decompression. ITU-T Recommendation Q.52 (2001), Signalling between international switching centres
42、 and stand-alone echo control devices. ITU-T Recommendation Q.400 (1988), Forward line signals. ITU-T Recommendation Q.931 (1998), ISDN user-network interface layer 3 specification for basic call control. ITU-T Recommendation T.30 (2003), Procedures for document facsimile transmission in the general
43、 switched telephone network. IETF RFC 1661 (1994), The Point-to-Point Protocol (PPP). IETF RFC 1812 (1995), Requirements for IP Version 4 Routers. IETF RFC 2131 (1997), Dynamic Host Configuration Protocol. IETF RFC 2427 (1998), Multiprotocol Interconnect over Frame Relay. IETF RFC 2460 (1998), Inter
44、net Protocol, Version 6 (IPv6) Specification. IETF RFC 2719 (1999), Framework Architecture for Signalling Transport. IETF RFC 2833 (2000), RTP Payload for DTMF Digits, Telephony Tones and Telephony Signals. IETF RFC 2960 (2000), Stream Control Transmission Protocol. IETF RFC 3550 (2003), RTP: A Tran
45、sport Protocol for Real-Time Applications. IEEE 802 (2001), IEEE Standards for Local and Metropolitan Area Networks: Overview and Architecture. 3 Definitions Definitions relating to the IP-CME are as follows: 3.1 IP-based CME (IP-CME): IP-CME constitutes a general class of equipment that permits con
46、centration of a number of IP ports on a reduced number of transmission channels over IP-based networks. 3.2 low rate encoding (LRE): The speech-coding methods with bit rates less than 64 kbit/s, e.g., the 32 kbit/s transcoding process defined in ITU-T Rec. G.726 applied to speech coded according to
47、ITU-T Rec. G.711. Furthermore, in VoIP systems, coding-decoding device (“codec“) that generate encoded blocks of voice signals in each periodical frame are usually adopted. For example, codecs such as the G.729 Annexes and G.723.1 are common in the VoIP field, and the basic intervals of their frames
48、 are usually multiples of 10 ms. 3.3 speech activity ratio: The ratio of the time speech and corresponding hangover occupies the trunk to the total measuring time, averaged over the total number of trunks carrying speech. 4 ITU-T Rec. G.769/Y.1242 (06/2004) 3.4 trunk: A bidirectional connection cons
49、isting of a forward channel and a backward channel between the SW (the International Switching Centre). Each channel in the trunk interface is identified by Trunk channel ID. 3.5 IP port: A bidirectional call stream between the IP-CMEs. An IP port in an IP transmission channel is distinguished by the IP port ID (IPP-ID) based on UDP port number and mapped to correspondent trunk. 3.6 IP transmission channel: A bidirectional multiplexed IP/UDP/RT
