1、INTERNATIONAL TELECOMMUNICATION UN ION ITU=T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU 1.375.3 (03/2000) SERIES I: INTEGRATED SERVICES DIGITAL NETWORK Overall network aspects and functions - General network requirements and functions Network capabilities to support multimedia services: Example
2、 of multimedia distribution service class - Switched digital broadcasting (SW ITU-T Recommendation 1.375.3 (Formerly CCITT Recommendation) STD-ITU-T RECMN I*375-3-ENGL 2000 4862593 Ob88726 553 ITU-T I-SERJES RECOMMENDATIONS INTEGRATED SERVICES DIGITAL NETWORK GENERAL STRUCTURE Terminology I. 1 10-1.
3、1 19 Description of ISDNs 1.120-1.129 General modelling methods I. 130-1.139 Telecommunication network and service atributes I. 140-1.149 General description of asynchronous transfer mode I. 150-1.199 Scope 1.200-1.209 General aspects of services in ISDN 1.2 10-1.219 Common aspects of services in th
4、e ISDN 1.220-1.229 Bearer services supported by an ISDN 1.230-1.239 Teleservices supported by an ISDN 1.240-1.249 Supplementary services in ISDN 1.250-1.299 Network functional principles 1.3 10-1.319 Reference models 1.320-1.329 Numbering, addressing and routing 1.330-1.339 Connection spes 1.340-1.3
5、49 Performance objectives 1.350-1.359 Protocol layer requirements 1.360-1.369 SERVICE CAPABILITIES OVERALL NETWORK ASPECTS AND FUNCTIONS ISDN USER-NETWORK INTERFACES Application of I-series Recommendations to ISDN user-network interfaces 1.420-1.429 Layer 1 Recommendations 1.430-1.439 Layer 2 Recomm
6、endations 1.440-1.449 Layer 3 Recommendations 1.450-1.459 Multiplexing, rate adaption and support of existing interfaces 1.460-1.469 Aspects of ISDN affecting terminal requirements 1.470-1.499 INTERNETWORK INTERFACES 1.500-1.599 MAINTENANCE PRINCIPLES I. 600-1.699 ATM equipment 1.730-1.739 Transport
7、 functions 1.740-1.749 Management of ATM equipment 1.750-1.799 B-ISDN EQUIPMENT ASPECTS For further details, please refer to the list of ITU-T Recommendations. Network capabilities to support multimedia services: Example of multimedia distribution service class - Switched digital broadcasting (SDB)
8、Summary This ITU-T Recommendation specifies the network capabilities required to support the switched digital broadcast service (SDB). The service requires a point-to-multipoint function that can be provided either by the access network topology or by the addition of a specific Replication Unit (RU)
9、. Another new functional element, the Broadcast Control Unit (BCU) instructs the RU which programs have to be delivered to a specific end user. This ITU-T Recommendation provides the service architecture and the reference configuration and then specifies the different functional elements and their i
10、nterfaces. Source ITU-T Recommendation 1.375.3 was prepared by ITU-T Study Group 13 (1997-2000) and approved under the WTSC Resolution 1 procedure on 10 March 2000. STD-ITU-T RECMN 1.375.3-ENGL 2000 W 486259L 0688728 326 FOREWORD The International Telecommunication Union (ITU) is the United Nations
11、specialized agency in the field of telecommunications. The ITU Telecommunication Standardization 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
12、 on a worldwide basis. The World Telecommunication Standardization Conference (WTSC), which 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 l
13、aid down in WTSC Resolution 1. In some areas of information technology which fall within ITU-Ts purview, the necessary standards are prepared on a collaborative basis with IS0 and IEC. NOTE In this Recommendation, the expression “Administration“ is used for conciseness to indicate both a telecommuni
14、cation administration and a recognized operating agency. INTELLECTUAL PROPERTY RIGHTS ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. takes no position concerning the evidence, validity or
15、 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 Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to
16、 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. o ITU 2001 All rights reserved. No part of this publication may be reproduced or utilized in any form or by any
17、means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the ITU. 1 2 3 4 5 5.1 6 6.1 6.2 6.3 6.4 6.5 6.6 7 STD*ITU-T RECRN I.375.3-ENGL 2000 m 4862593 0688729 262 m CONTENTS Page Scope References Ab brevi ations . Description . The reference configur
18、ation . Functional elements 5.1.1 Customer premises equipment functions 5.1.2 Network functions . Interfaces Content server . core network management system Core network management system - access network management system . Access network management system - BCU . Core network management system . R
19、EMUX STB - access network BCU . RU Logical interrelations 7.1.1 Zapping channel 7.1.2 Standby channel 7.1.3 Audiovisual channel 7.1.4 Return channel . 1 1 1 2 ITU-T Recommendation 1.375.3 Network capabilities to support multimedia services: Example of multimedia distribution service class - Switched
20、 digital broadcasting (SDB) 1 Scope This ITU-T Recommendation specifies network requirements for the switched digital broadcast service using ATM based network. 2 References The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute
21、provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; all users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Reco
22、mmendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. - ITU-T Recommendation G.902 (1 999, Framework Recommendation on functional access networks -Architecture and functions, access types, management and service node aspects. - ITU
23、-T Recommendation H.222.0 (2000) I ISO/EC 1381 8-1 2000, Information technology - Generic coding of moving pictures and associated audio information: Systems. ITU-T Recommendation H.222.1 (1 996), Multimedia multiplex and synchronization for audiovisual communication in ATM environments. - ITU-T Rec
24、ommendation 1.375.1 (1998), Network capabilities to support multimedia services - General aspects. ITU-T Recommendation 1.375.2 (1 998), Network capabilities to support multimedia services - Example of multimedia retrieval service class - Video-on-demand service using ATM-based network. ITU-T Recomm
25、endation 1.414 (1997), Overview Recommendations on layer I for ISDN and B-ISDN customer accesses. ITU-T Recommendation J.82 (1 996), Transport of MPEG-2 constant bit rate television signals in B-ISDN. - - - - 3 Abbreviations This ITU-T Recommendation uses the following abbreviations: BCU Broadcast C
26、ontrol Unit CPE Customer Premises Equipment POTS Plain Old Telephony Service REMUX Re-multiplexer RU Replication Unit SDB Switched Digital Broadcasting STD-ITU-T RECMN 1.375-3-ENGL 2000 H 4862591 0688733 910 STB Set-top Box TE Terminal Equipment 4 Description The SDB service offers access to a large
27、 number of broadcast programs over access networks with a relatively low capacity requirement per end-user. The service requires that the end-user has control capabilities for program selection and the network provides replication and routing functions for the selected programs. Unlike the existing
28、TV broadcasting or CATV services, broadcast programs are delivered to a Replication Unit (RU), generally located in the access network, and from there the programs are distributed to the end-users according to their selection. Figure 1 below shows the architecture of the switched digital broadcast s
29、ervice. End-user(s) select a desired program from the program menu downloaded fi-om a content server. Broadcast programs are delivered to the RU via appropriate protocols before the program selection is performed. Given the end-users program selection, the Broadcast Control Unit (BCU) instructs the
30、RU to deliver the program to the end-user(s). The RU can be implemented either in the Access Network or in the Core Network by network operators or service providers. T1315350-99 Access Network Core Network Content server 1 + - - - -+ Broadcast Control - BroadcastProgram Figure 1D.375.3 - Switched D
31、igital Broadcast Service Architecture 5 The reference configuration Figure 2 provides the reference configuration. The functions of access network and their interfaces are specified in ITU-T Recommendation G.902. The access network can provide the replication function for the SDB basically in two wa
32、ys. If the access network topology provides point-to- multipoint communication, the signals are replicated implicitly. If this is not the case a specific RU has to be provided in the access network or in the core network. The core network performs a re- multiplexer (REMUX) function to adapt program
33、transport streams for transport and delivery by the network (i.e. Access Network plus Core Network).The core network also performs a transport function. In general, the REMUX function is done by several devices distributed geographically. The REMUX function can also be located in the Content Server,
34、 and deliver the program streams directly in the appropriate form. In this case, there is no REMUX in the core network. The BCU function, can be implemented by one device or by more devices working in cascade and can be located either in the access network or in the core network. STD-ITU-T RECMN 1-3
35、75.3-ENGL 2000 E 4862573, Ob88732 857 The management systems of access and core networks can be two different systems, but both networks can also be managed by one system. In case of two separate management systems, there is an interface between them. The interfaces for network element management be
36、tween the management systems and their networks are not drawn in the figure. The customer premises equipment (CPE) consists in its minimal form of one STB and a terminal (e.g. television set). But the CPE can also contain several STBs and/or terminals. Access Network Management System I I - Core Net
37、work Management - System CPE ISTBj Core Network UNINNIhon-ATM Content 1 NOTE - There are several alternatives of RU implementation. RUS can be provided in the Access Network andor the Core Network. Figure 24.375.3 - Reference configuration for SDB service 5.1 Functional elements 5.1.1 Customer premi
38、ses equipment functions The CPE provides the functions of devices at the end-users home used to provide SDB. The functions of the CPE for SDB includes the functions of Set-top Box (STB) and functions of the Terminal Equipment (TE). The TE may be a TV set. The STB functions present to the user variou
39、s forms of menus and selection objects for desired program and other control purposes such as e.g. authentication, on-line program purchase, etc. They contain the necessary hardware and software functions to provide SDB service in the home. The STB acts as an interface and an adaptation unit between
40、 the NT and the TE. The STB functions provide the platform on which the services user application runs, and the infrastructure for user applications to offer sophisticated user interfaces. 5.1.2 Network functions For the SDB service, the network functions are replication and broadcasting of program
41、transport streams, and on-demand delivery of program transport streams to end-users. The network (i.e. Access Network plus Core Network) does not perform authorization, nor authentication, nor conditional access. However, the network can evolve to perform some or all of these functions. 5.1.2.1 Broa
42、dcast control unit The BCU interprets end-users selections sent by means of the zapping protocol, and directs the RU to send the selected program transport stream to the STB. STD=ITU-T RECMN 1.375-3-ENGL 2000 D 48bZ593 Ob88733 793 = To this end the BCU needs for all the program transport streams tha
43、t can be selected in the domain of the access network, the relation between the identifier of the program transport stream (simply called “program identifier“) and the identifiers (VPI+VCI) of the VC on which this identified program transport stream is delivered to the access network, plus the bandw
44、idth of this VC. At the time VCs with program transport streams are set up, it is necessary that the management system provides the BCU the needed information about the relation between the program identifiers and the VC parameters. 5.1.2.2 Replication unit An RU function is an important function fo
45、r switched digital broadcast (SDB). It replicates “broadcast“ multimedia signals to a group of CPEs. The replication function is performed by one or more devices, or implicitly by the transport function of the access network. For example, if the access network is based on bus architecture like coax
46、CATV, the replication function is implicitly implemented by the coax cable. The coax bus cable replicates electronic signal and delivers to signal receivers. It automatically provides point-to- multipoint signal transport, therefore, there is no explicit physical entity dedicated for replication. On
47、 the other hand, if the access network architecture is a star topology like a traditional optical fibre network, there is no implicit replication function in the access network. The fibre provides only point-to-point signal transport and it requires the replication function to have point-to-multipoi
48、nt capability. In this case, there are two possible alternatives of RU functions location, one is in the access network, and the other is in the core network. An access network is based on a transmission network and has no explicit switching function. The RU function that is located in the access ne
49、twork replicates “broadcast“ signals to a set of subscribers. It is a simple point-to-multipoint function. The access network with RU function might lose flexibility, for example, instead of gaining point-to-multipoint capability, the network might lose point-to-point signalling capability or bidirectional signalling capability. The RU function is also able to be located in the core network. For example, if the core network is based on ATM switches, it is possible the switches have the replication function. In this case, the access network can transpo
