1、 International Telecommunication Union ITU-T J.281TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (03/2005) SERIES J: CABLE NETWORKS AND TRANSMISSION OF TELEVISION, SOUND PROGRAMME AND OTHER MULTIMEDIA SIGNALS Digital transmission of television signals Requirements for multichannel video signal tran
2、smission over IP-based fibre network ITU-T Recommendation J.281 ITU-T Rec. J.281 (03/2005) i ITU-T Recommendation J.281 Requirements for multichannel video signal transmission over IP-based fibre network Summary Recent mass deployments of broadband optical access networks allow general consumers to
3、use 100 Mbit/s or more bandwidth at affordable costs. This bandwidth has potential of transmitting high-quality video signals up to HDTV. Internet Protocol is generally employed on the broadband fibre networks. This Recommendation provides the requirements of multichannel video transmission system o
4、ver IP-based fibre network including cable television networks with high-level architecture. It is assumed that the television services are provided in the same way as the current CATV system. The unicast based VoD, which involves a unicast session, is not taken into consideration. However, the broa
5、dcast based VoD, which has been integrated into the CATV broadcasting system, is taken into account. In this Recommendation, the broadcast based VoD is assumed to be provided by a multicast stream instead of a broadcast signal, and can be treated as a broadcasting service. Source ITU-T Recommendatio
6、n J.281 was approved on 1 March 2005 by ITU-T Study Group 9 (2005-2008) under the ITU-T Recommendation A.8 procedure. ii ITU-T Rec. J.281 (03/2005) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications. The ITU Telecommun
7、ication 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 on a worldwide basis. The World Telecommunication Standardization Assemb
8、ly (WTSA), 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 laid down in WTSA Resolution 1. In some areas of information technology which
9、 fall within ITU-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 thi
10、s Recommendation 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 languag
11、e such as “must“ 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 Rec
12、ommendation may involve 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 a
13、pproval of this Recommendation, ITU had not 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 T
14、SB patent database. ITU 2005 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. J.281 (03/2005) iii CONTENTS Page 1 Scope 1 2 References. 1 2.1 Normative. 1 3 Definitions 2 4 Abbreviations 2 5 System as
15、sumption . 3 5.1 Headend 3 5.2 Core Network . 3 5.3 Access Network 3 5.4 Connection with the Internet 4 5.5 STB. 4 6 Requirements 5 6.1 Transmission and service . 5 6.2 Packet format 5 6.3 Multiplexing and programme selection 6 6.4 Network QoS and bandwidth . 6 6.5 STB. 6 6.6 Security. 6 6.7 Coordin
16、ation with other services and technologies 7 ITU-T Rec. J.281 (03/2005) 1 ITU-T Recommendation J.281 Requirements for multichannel video signal transmission over IP-based fibre network 1 Scope This Recommendation defines the requirements for a multichannel video signal transmission system over IP-ba
17、sed fibre network. The video service is expected to be the same as the current digital broadcasting service in which high-quality video programmes including HDTV are provided as a part of a set of services, such as data services, conditional access system and electric programme guide. 2 References 2
18、.1 Normative The following ITU-T Recommendations and other references contain provisions which, through reference 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 revisio
19、n; users of this Recommendation are therefore encouraged to investigate 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 Re
20、commendation does not give it, as a stand-alone document, the status of a Recommendation. ITU-T Recommendation H.222.0 | ISO/IEC 13818-1 (2000), Information technology Generic coding of moving pictures and associated audio information: Systems. ITU-T Recommendation G.983.1 (2005), Broadband optical
21、access systems based on Passive Optical Networks (PON). ITU-T Recommendation G.983.3 (2001), A broadband optical access system with increased service capability by wavelength allocation. ITU-T Recommendation G.984.1 (2003), Gigabit-capable Passive Optical Networks (GPON): General characteristics. IT
22、U-T Recommendation J.183 (2001), Time-division multiplexing of multiple MPEG-2 transport streams over cable television systems. ITU-T Recommendation J.193 (2004), Requirements for the next generation of set-top boxes. IEEE Std. 802.3AH (2004), Technology Telecommunications and Information Exchange B
23、etween Systems LAN/MAN Specific Requirements Part 3: Carrier Sense Multiple Access with Collision Detection (CSMA/CD) Access Method and Physical Layer Specifications Amendment: Media Access Control Parameters, Physical Layers and Management Parameters for Subscriber Access Networks. 2 ITU-T Rec. J.2
24、81 (03/2005) 3 Definitions This Recommendation defines the following term: 3.1 transport stream (TS): A data structure defined in ITU-T Rec. H.222.0 | ISO/IEC 13818-1. 4 Abbreviations This Recommendation uses the following abbreviations: CATV Cable Television ECM Entitlement Control Message EMM Enti
25、tlement Management Message EPG Electronic Programme Guide FTTH Fibre to the Home FTTB Fibre to the Building HDTV High Definition TeleVision IP Internet Protocol MAC Media Access Control MPEG Moving Picture Experts Group NIT Network Information Table OLT Optical Line Terminal ONU Optical Network Unit
26、 PES Packetized Elementary Stream PSI Programme-Specific Information PHY Physical Layer QoS Quality of Service RTP Real-time Transport Protocol STB Set-Top Box TS Transport Stream UDP User Datagram Protocol VoD Video on Demand ITU-T Rec. J.281 (03/2005) 3 5 System assumption To help to understand th
27、e requirement of the system described in the following clause, this clause describes the system assumptions and the reference architecture. The presented system consists of mainly four components: Headend, Core network, Access network and STB. These components are briefly explained in Figure 1. Figu
28、re 1/J.281 Examples of system configuration 5.1 Headend Headend plays a similar role to CATVs headend. It coordinates video signal and produces transport streams. Encapsulation into IP packets also takes place here. At least one Headend must exist on the system. Two or more Headends on the same syst
29、em are also possible. 5.2 Core Network Core Network is responsible for transporting the injected IP packets to each Access Network with sufficient transfer quality. It has appropriate bandwidth, QoS functions and/or network architecture so as to guarantee the quality needed for video transmission se
30、rvices, against the traffic generated by the conventional Internet applications, such as WWW, e-mail. 5.3 Access Network Access Network connecting STB and Core Network provides sufficient bandwidth for video services. It also provides connectivity between customer premises equipment and the Internet
31、. This Recommendation assumes that the Access Network is an FTTx network. Several FTTx architectures are available, and the similarity among these architectures may cause confusion. This Recommendation focuses on FTTH, which is defined that ONU is installed in/outside the houses, and FTTB, which is
32、defined that ONU is installed in a building. 4 ITU-T Rec. J.281 (03/2005) Figure 2 shows examples of Access Network. Access Network consists of OLT, ONU and Optical Fibre connecting them. In some cases, a splitter may be inserted between ONU and OLT. In some Recommendations or standards, particularl
33、y G-series Recommendations of ITU-T such as ITU-T Recs G.983 and G.984, the optical fibre network between OLT and ONU is called the Optical Distribution Network (ODN). Figure 2/J.281 Examples of Access Network A number of optical access network technologies have been developed, and several carriers
34、have deployed some of them. The following are technologies relevant to this Recommendation at the time of publication. ITU-T Rec. G.983.1; ITU-T Rec. G.983.3; ITU-T Rec. G.984.1; IEEE Std. 802.3AH. 5.4 Connection with the Internet Connectivity with the Internet can be provided on this system. Severa
35、l connecting points can be prepared for Internet services. The connecting point between Access Network and Core Network, as depicted in Figure 1-a, is one example. Locating the connecting point as Figure 1-a makes it easier to maintain the quality of service within Core Network. A connecting point c
36、an be located within Headend or Core Network as depicted in Figure 1-b. In this case, the Core Network should offer a measure that can maintain transmission quality of video services. 5.5 STB STB is responsible for terminating all network functions in all layers as well as providing conventional STB
37、 functions such as video decoding. An example of protocol stack is shown in Figure 3. The protocol stack is divided into two parts: 1) the group of layers below RTP layer, that is primarily responsible for transmission; 2) the group of layers above MPEG-2 TS layer that is primarily responsible for s
38、ervices. These two groups of layers are not closely related; therefore, the service operation and the network operation are expected to be less dependent of each other. ITU-T Rec. J.281 (03/2005) 5 Figure 3/J.281 An example of protocol stack The following are the assumptions regarding the protocol s
39、tructure: Services are operated over MPEG-2 TS system. Multiple programmes are provided. Several hundreds of programmes may be provided. IP multicast is employed for distribution of video contents. 6 Requirements 6.1 Transmission and service The following are the requirements regarding the transmiss
40、ion and service: IP network should rigidly control the distribution area. If multiple broadcasters provide TSs independently, each TS should retain its independence. IP network should eliminate or reduce the jitter caused in the network. High transmission efficiency should be realized. TS that has b
41、een transmitted through networks must be compliant with ITU-T Rec. H.222.0 | IEC/ISO 13818-1. IP network should minimize transmission latency. NOTE Future Recommendations will define a tolerable value of transmission latency for FTTx-based IP video services. Although transmission latency is for furt
42、her study, hundreds of milliseconds is suggested as an appropriate value for latency in some documents. 6.2 Packet format The following are the requirements regarding the packet format: Error protection encoding that is performed on either MPEG-2 TS packets or RTP packets should work against IP-leve
43、l packet-loss while keeping the transmission latency low enough as described in 6.1. Packet header should enable STB to recognize the sequence of transmitted IP packets. 6 ITU-T Rec. J.281 (03/2005) 6.3 Multiplexing and programme selection The following are the requirements regarding the multiplexin
44、g and programme selection issues: Programmes should be received on transport stream basis. The information regarding the multiplexing should be provided by PSI, which is defined in ITU-T Rec. H.222.0 | IEC/ISO 13818-1. NIT should contain the sufficient information to specify the logical location of
45、programmes. The multiplexing scheme defined in ITU-T Rec. J.183 should be employed. STB should minimize the programme selection time, which is desired to be the same degree as a conventional cable television STB. 6.4 Network QoS and bandwidth The following are the requirements regarding the network
46、QoS and bandwidth issues: Core Network should provide sufficient bandwidth to enable all programmes to be distributed simultaneously. Access Network must provide sufficient bandwidth that enables to distribute at least one programme for each user. Quality classification should be defined for Core Ne
47、twork and Access Network. NOTE It is necessary to consider the allocation of bandwidth and priority to other services as a total network management policy. Priority of a video service over a telephone service, for example, is up to the operator and the broadcaster. This Recommendation does not defin
48、e total network management issues while the quality of video service is maintained. 6.5 STB The following are the requirements regarding STB: IP address should be assigned automatically. STB should support services based on additional information attached to MPEG-2 TS. STB should provide copy contro
49、l. Headend and/or IP network should prevent unauthorized STB from receiving any programme. STB should meet requirements defined in ITU-T Rec. J.193 except definitions regarding physical layer and analogue video/audio services. NOTE ITU-T Rec. J.193 defines functional requirements for the Next Generation STB. Some requirements can be applied to the STB of this Recommendation, although requirements associated with physical layer and analogue video/audio services should not be applied. 6.6 Security The
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