1、INTERNATIONAL TELECOMMUNICATION UNION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU JA10 (04/97) SERIES J: TRANSMISSION OF TELEVISION, SOUND PROGRAMME AND OTHER MULTIMEDIA SIGNALS Interactive services Basic principles for a worldwide common family of systems for the provision of interactive
2、television services ITU-T Recommendation J.II.0 (Previously CCIlT Recommendation) STD-ITU-T RECMN J-110-ENGL li997 9 48b2591 Ob32855 290 ITU-T J-SERIES RECOMMENDATIONS TRANSMISSION OF TELEVISION, SOUND PROGRAMME AND OTHER MULTIMEDIA SIGNALS General Recommendations General Recommendations concerning
3、sound-programme transmissions Performance characteristics of sound-programme circuits Characteristics of equipment and lines used for setting up sound-programme circuits Characteristics of equipment for coding analogue sound-programme signals Digital transmission of sound-programme signals Character
4、istics of circuits for television transmissions Systems for television transmission over metallic lines and interconnection with radio-relay links Digital transmission of television signals Specific Recommendations for television transmission Transmission of signals with multiplexing of video, sound
5、 and data, and signals of new J. 1-J.9 J. 1O-J. 19 5.20-5.29 J.30-J.39 5.40-3.49 J.50-J.59 J. 60-5.69 J.70-J.79 J.80-J.89 J.90-J.99 J. 100-J. 109 systems Interactive services 5.110-5.119 For further details, please refer to ITU-T List of Recommendations. FOREWORD The IT-T (Telecommunication Standard
6、ization Sector) is a permanent organ of the International Telecommunication Union (ITLJ). The IT-T is responsible for studying technical, operating and tariff questions and issuing Recommen- dations on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunica
7、tion Standardization Conference (WTSC), which meets every four years, establishes the topics for study by the IT-T Study Groups which, in their turn, produce Recommendations on these topics. The approval of Recommendations by the Members of the ITLJ-T is covered by the procedure laid down in WTSC Re
8、solution No. 1 (Geneva, October 1996). IT-T Recommendation J.110 was prepared by IT-T Study Group 9 (1997-2000) and was approved under the WTSC Resolution No. 1 procedure on the 22nd of April 1997. NOTE In this Recommendation, the expression “Administration” is used for conciseness to indicate both
9、a telecommunication administration and a recognized operating agency. O ITU 1997 All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the ITLJ. Re
10、commendation 5.110 (04197) 1 CONTENTS 1 Scope 2 References 3 Terms and definitions . 4 Abbreviations . 5 Interactivity and the role of interaction paths . 6 Reference model for the interaction channel 7 Specification of the broadcast channel . 8 Specification of the interaction channel . 8.1 Interac
11、tion channel transport mechanisms 8.2 Interaction channel Characteristics 9 Management functions . Appendix I - Technical parameters under study . Page 1 1 1 2 2 2 2 4 4 5 5 5 ii Recommendation 5.110 (04197) STD-ITU-T RECMN J*110-ENGL 1777 t8b2591 Ob32858 TTT SUMMARY This Recommendation, which has b
12、een produced in conjunction with the broadcasting study groups of the Radiocommunication Sector of the ITU, gives general guidance for the harmonious development of interactive television services. It covers the subject areas of interaction channels, interactive services and transport mechanisms. IN
13、TRODUCTION The development of new digital technology has led to the convergence of broadcasting, telecommunications and computers. There has been rapid progress towards enhanced digital television broadcasting using HFC, SMATV, MMDS, LMDS, ISDN, ADSL, terrestrial over-air transmission, satellite del
14、ivery systems, etc. Reliance upon digital technology provides opportunities for the introduction of interactive services. Interactivity may be required at a number of levels, each having a variety of Quality of Service requirements for the interaction channel. The interaction channel, often referred
15、 to as the return channel, generally includes both upstream and downstream paths, but in some instances may use only an upstream path to the source of the service. Interactivity can be local only without a return path, or simple interactivity using a unidirectional interaction channel or in its full
16、est form using a bidirectional interaction channel to and from the source of the service. There is, thus, a need for the harmonization of systems for the provision of interactive services. Recommendation 5.110 (04/97) . 111 Recommendation 5.110 BASIC PRINCIPLES FOR A WORLDWIDE COMMON FAMILY OF SYSTE
17、MS FOR THE PROVISION OF INTERACTIVE TELEVISION SERVICES (Geneva, 1997) 1 Scope This Recommendion gives general guidance r a worldwide common family of systems for the provision of interactive television services to the public. It is a preliminary step towards facilitating the interoperability of int
18、eractive services. It is intended to assist in the preparation of future Recommendations for specific services which should take into account the output from other ITU groups dealing with multimedia services. This Recommendation is based on the following principles: a) There should be maximum common
19、ality in the techniques used for interactive television services delivered by HFC, SMATV, Mh4DS, LMDS, ISDN, ADSL, terrestrial over-air transmission, satellites, etc. The interaction channel should be designed as a “container” able to transport data services (including video, audio and the associate
20、d data signals) in a transparent and flexible way. b) Guidance for harmonizing the development of interactive television services can be found in the service architecture shown below. It is beyond the scope of this Recommendation to specify the technical details of the transport and access networks
21、used for media delivery and application interaction. A preliminary list of technical parameters under study which may affect such specifications is provided in informative Appendix I. 2 References The following ITU-T Recommendations and other references contain provisions which, through reference in
22、 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; all users of this Recommendation are therefore encouraged to investigate the possibility of applying the most rec
23、ent edition of the Recommendations and other references listed below. A list of the currently valid IT-T Recommendations is regularly published. il ITU-T Recommendation J.l (1997), Terminology far new services in television and sound-programme ransmission. ITU-T Recommendation J.83 (1997), Digital m
24、ulti-programme systems for television, sound and data services for cable distribution. ITU-T Recommendation J.84 (1 997), Distribution of digital multi-programme signals for television, sound and data services through SMATV networks. ITU-T M.3000-Series of Recommendations, Telecommunication manageme
25、nt network. ITU-T Recommendation 1.414 (1993), Overview of Recommendations on layer 1 for ISDN and B-ISDN customer accesses. Pl 31 41 51 3 Terms and definitions The terms and definitions in Recommendation J. 1 apply and are augmented by the definitions below for the purposes of this Recommendation.
26、3.1 broadcast channel: A unidirectional, broadband, point-to-multipoint channel, which may include video, audio and data. The broadcast channel is established from the services provider to the users. It may include the forward interaction path. Recommendation J.110 (04/97) 1 STDBITU-T RECMN J-110-EN
27、GL 1997 4Bb2591 Ob328b0 b58 3.2 interaction channel: A bidirectional channel between the user and the service provider for interaction purposes. In certain implementations the interaction channel could also carry a user selected broadcast service. In general, the interaction channel is formed by: -
28、return interaction path (return channel): A communication channel from the user to the service provider. It is multiple point-to-point. forward interaction path: An individual communications channel from the service provider to the user. It may be embedded into the broadcast channel. This channel ma
29、y not be present in all implementations. - 4 Abbreviations This Recommendation uses the following abbreviations: ADSL Asymmetric Digital Subscriber Line GSM HFC Hybrid Fibre Coax ISDN Integrated Services Digital Network LMDS Local Multipoint Distribution System MMDS Multichannel Multipoint Distribut
30、ion System SMATV Satellite Master Antenna Television TMN Telecommunications Management Network Global Systems for Mobile communication 5 Interactivity and the role of interaction paths The basic requirement of an interaction channel is that the user be able to respond in some way to the interactive
31、service. This response may take the form of “voting” for a particular participant in a competitor show, “purchasing” goods that are demonstrated or advertised in a shopping channel programme, etc. This would be achievable within a one-way (reverse direction) narrow-band path. A higher level of inter
32、activity might require that a user, who has made a response to an interactive service, be sent an acknowledgement, This might be the case where the consumer has made a credit card purchase from a shopping channel via the basic interaction channel. That consumer would expect to receive an acknowledge
33、ment that his or her credit card transaction had been accepted. This level of interactivity would require a two-way interaction channel, one in the reverse direction, the other the forward direction. A further level of interactivity would occur where, in response to information in the interactive se
34、rvice, the consumer requests further information on particular topics from the source of the service, or from a central database via the source of the interactive service. This could require that the forward channel be broadband. In this particular example, the reverse path would only need to be a n
35、arrow-band one, but it is possible that applications will arise whereby the consumer will need to make a broadband responseicontribution to the interactive service and also receive a broadband “answer” from the service source. 6 Reference model for the interaction channel A reference model for the s
36、ystem architecture of a narrow-band interaction channel in a broadcasting scenario is shown. In this reference model, two channels are established between the user and the service provider, as in Figure 1. The detailed reference model is presented in Figure 2. 7 Specification of the broadcast channe
37、l In Figure 2, the top section represents the unidirectional broadcast channel. This is fully specified by other relevant Recommendations of the ITU (e.g. Recommendation J.83 for HFC and Recommendation 5.84 for SMATV). 2 Recommendation 5.110 (04197) STD-ITU-T RECMN J*LLO-ENGL 1997 qBb2.591 Ob32Abl 5
38、94 Broadcast Broadcast channel service Interactive Interaction channel service provider Foward interaction path Return interaction path - T0903830-Wd01 Figure VJ.110 - Illustration of channel terminology in interactive television systems Broadcast - Transmission network channel A, independent - Tran
39、smission network independent Transmission network physical link Figure 2/J.110 - Functional reference model for interactive television services T0903840-9Wd02 3 Recommendation 5.110 (04/97) STD-ITU-T RECMN J-110-ENGL 1997 H 48b2571 Ob328b2 920 D 8 Specification of the interaction channel The lower p
40、art of Figure 2 represents the bidirectional interaction channel. Several interfaces exist within the interactive system. These are related to specific areas where it is proposed that standards should be developed. These are: A,: Set-top unit to interactive interface module. This can be either inter
41、nal or external to a set-top unit. This interface is network independent. Ao: Set-top unit to network interface unit. This can be either internal or external to a set-top unit. This interface is network independent. Ab: Interactive interface module to interaction media. This interface is network dep
42、endent. Al: Network interface unit to broadcast and interaction media. This interface is network dependent. A,: Interaction media to interactive network adaptor. This interface is network dependent. A4: Interaction media and broadcast media to interactive network and broadcast network adaptors. This
43、 interface is network dependent. A,: Interactive network adaptor to interactive service providers system. This can either be connected directly to a server or via a “core network”. This interface is network independent. Ag: Interactive and broadcast network adaptors to interactive service and broadc
44、ast service providers systems. This can either be connected directly to a server or via a “core network”. This interface is network independent. The detailed specification of the interfaces at the reference points shown in Figure 2 is likely to be the subject of future IT-T Recommendations. It is ex
45、pected that the interactive service control used will take advantage of modem design techniques, such as the use of layered protocols. Where more than one interaction network is required (e.g. SMATV to VSAT), several interaction media to interaction media interfaces may be used in series. Where the
46、broadcast channel and the interaction channel are camed over the same medium, - use of existing cable systems, by utilizing the return channel capability of the cable systems or of SMATV systems; - the use of satellite-based systems such as VSAT, to link the nodes which concentrate the signals from
47、a number of different users to a service provider; - a simplified version of mobile telephone equipment, using the same cellular stations as the mobile service, or possibly using separate receiving stations located at the television transmitter. In the case of using the same cellular mobile stations
48、, a more simplified version of the data transmission protocol may be used; - use of the existing public telephone (telecommunications) networks, including ISDNB-ISDN/ADSL (see Recommendation 1.4 i 4); 4 Recommendation 5.110 (04197) STD-ITU-T RECMN J-LLO-ENGL 1997 W 48b259L Ob328b3 3b7 = - - use of t
49、he Internet. a similar solution may be possible by using mobile service via low-Earth orbit satellites (LEOS); 8.2 Interaction channel characteristics 8.2.1 Data rate The preliminary studies for the return interaction path user bit rates have been grouped into three categories: a) Low data rate (L), implies a data rate of approximately 150 bids, or even less, for simple rem commands, including simple error correction. Medium data rate (M), implies a data rate of approximately 6 to 7 kbits/s for more complex applications and instru
