1、 I n t e r n a t i o n a l T e l e c o m m u n i c a t i o n U n i o n ITU-T J.1105 TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (10/2016) SERIES J: CABLE NETWORKS AND TRANSMISSION OF TELEVISION, SOUND PROGRAMME AND OTHER MULTIMEDIA SIGNALS Switched digital video over cable networks Requirement o
2、f channel switching service over hybrid fibre and coaxial based network Recommendation ITU-T J.1105 Rec. ITU-T J.1105 (10/2016) i Recommendation ITU-T J.1105 Requirement of channel switching service over hybrid fibre and coaxial based network Summary Recommendation ITU-T J.1105 describes the require
3、ment of channel switching service over Hybrid fibre and coaxial based network. The cable broadcasting system has been changed to use resources efficiently and transmits it to easily accommodate the varying needs of subscribers. Therefore, it is necessary to define the requirement of channel switchin
4、g service using bandwidth effectively on HFC network environment. This Recommendation contains descriptions for requirement of channel switching service over hybrid fibre coaxial (HFC) based networks. History Edition Recommendation Approval Study Group Unique ID* 1.0 ITU-T J.1105 2016-10-14 9 11.100
5、2/1000/13057 * To access the Recommendation, type the URL http:/handle.itu.int/ in the address field of your web browser, followed by the Recommendations unique ID. For example, http:/handle.itu.int/11.1002/1000/11830-en. ii Rec. ITU-T J.1105 (10/2016) FOREWORD The International Telecommunication Un
6、ion (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions
7、and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on t
8、hese 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-Ts purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. NOTE In this Recommendation, the ex
9、pression “Administration“ is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applic
10、ability) 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“ and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with th
11、e Recommendation is required of any party. INTELLECTUAL PROPERTY RIGHTSITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicabil
12、ity 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 received notice of intellectual property, protected by patents, which may be required to implement this
13、 Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at http:/www.itu.int/ITU-T/ipr/. ITU 2017 All rights reserved. No part of this publication may be reproduced, by any means whats
14、oever, without the prior written permission of ITU. Rec. ITU-T J.1105 (10/2016) iii Table of Contents Page 1 Scope . 1 2 References . 1 3 Definitions 1 3.1 Terms defined elsewhere 1 3.2 Terms defined in this Recommendation . 1 4 Abbreviations and acronyms 1 5 Conventions 2 6 Overview . 2 7 Requireme
15、nts 3 7.1 Control function 3 7.2 Channel switching function 3 7.3 Transmission function 3 7.4 Subscriber function . 4 Annex A Example of channel switching service 5 Bibliography. 7 Rec. ITU-T J.1105 (10/2016) 1 Recommendation ITU-T J.1105 Requirement of channel switching service over hybrid fibre an
16、d coaxial based network 1 Scope The proposed channel switching service is possible to share and provide the same frequency bandwidth for communication and broadcasting service without implementing a complicated system. The proposed channel switching service is required to support downstream service
17、only. 2 References 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 r
18、evision; 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 t
19、his Recommendation does not give it, as a stand-alone document, the status of a Recommendation. ITU-T J.210 Recommendation ITU-T J.210 (2006), Downstream RF interface for cable modem termination systems. ITU-T J.222.1 Recommendation ITU-T J.222.1 (2007), Third-generation transmission systems for int
20、eractive cable television services IP cable modems: Physical Layer specification. ITU-T J.222.2 Recommendation ITU-T J.222.2 (2007), Third-generation transmission systems for interactive cable television services IP cable modems: MAC and Upper Layer protocols. 3 Definitions 3.1 Terms defined elsewhe
21、re None. 3.2 Terms defined in this Recommendation None. 4 Abbreviations and acronyms This Recommendation uses the following abbreviations and acronyms: CM Cable Modem CMTS Cable Modem Termination System DOCSIS Data Over Cable Service Interface Specifications HFC Hybrid Fibre Coaxial MAC Media Access
22、 Control QAM Quadrature Amplitude Modulation 2 Rec. ITU-T J.1105 (10/2016) 5 Conventions In this Recommendation: The keywords “is required to“ indicate a requirement which must be strictly followed and from which no deviation is permitted if conformance to this Recommendation is to be claimed. The k
23、eywords “is recommended“ indicate a requirement which is recommended but which is not absolutely required. Thus this requirement need not be present to claim conformance. The keywords “is prohibited from“ indicate a requirement which must be strictly followed and from which no deviation is permitted
24、 if conformance to this Recommendation is to be claimed. The keywords “can optionally“ indicate an optional requirement which is permissible, without implying any sense of being recommended. This term is not intended to imply that the vendors implementation must provide the option and the feature ca
25、n be optionally enabled by the network operator/service provider. Rather, it means the vendor may optionally provide the feature and still claim conformance with the specification. In the body of this Recommendation and its annexes, the words shall, shall not, should, and may sometimes appear, in wh
26、ich case they are to be interpreted, respectively, as is required to, is prohibited from, is recommended, and can optionally. The appearance of such phrases or keywords in an appendix or in material explicitly marked as informative are to be interpreted as having no normative intent. 6 Overview Chan
27、nel switching service over HFC-based network can be provided on a cable channel switching system as shown in Figure 1. The cable channel switching system includes control function, channel switching function, multiplexing and transmission function, and receiver function. Figure 1 Channel switching s
28、ervice and system It is possible that one or more broadcasting services is contained in one physical channel (i.e., 6 or 8 MHz). The frequency allocation of broadcasting service and communication service is shown in Figure 2. Rec. ITU-T J.1105 (10/2016) 3 Figure 2 Frequency allocation of channel swi
29、tching service 7 Requirements 7.1 Control function The control function of the channel switching service system is required to collect the subscribers selected broadcasting service channel information in real time. The control function of the channel switching service system is required to update th
30、e subscribers selected broadcasting service channel information in real time. 7.2 Channel switching function The channel switching function of the channel switching service system is required to distinguish a packet of selected broadcasting channel. It is required to send only packets of selected br
31、oadcasting channel as well as to drop packets of non-selected broadcasting channel. 7.3 Transmission function 7.3.1 Physical channel Each physical channel of the channel switching service system is required to include one and/or more broadcasting service data. The broadcasting and communication hybr
32、id service channel switching service system is required to be provided in the broadcasting channels. The communication data of the channel switching service system is required to transmit using the non-selected broadcasting channels. 7.3.2 Service stream Identifier in service packet header of the ch
33、annel switching service system is required to distinguish the broadcasting service data from the communication service data. 4 Rec. ITU-T J.1105 (10/2016) Communication service data of channel switching service system is required to change media access control (MAC) frame to MPEG-2 TS packet. 7.3.3
34、Multiplexing The broadcasting data stream and communication data stream of the channel switching service system is required to multiplex in order to create a hybrid transmission data stream. In addition, the broadcasting data stream is required to be multiplexed prior to the communication data strea
35、m. 7.3.4 Transmission The input data format of quadrature amplitude modulation (QAM) modulator of channel switching service system is required to support the MPEG-2 TS. The selected broadcasting channels of the channel switching service system are required to be transmitted. Data stream for communic
36、ation service of the channel switching service system is required to be transmitted according to transmission scheduling for each physical channels. Channel bonding of the channel switching service system is recommended to be supported for communication data service. 7.4 Subscriber function The sele
37、cted channel of the channel switching service system is required to be received without any change. The information of channel switching of the channel switching service system is required to be transmitted to the transmission system. The cable modem (CM) of the channel switching service system is r
38、equired to obtain communication data by removing the broadcasting data in case of hybrid transmission data stream. Channel bonding of the channel switching service system is required to combine several distributed communication data. Rec. ITU-T J.1105 (10/2016) 5 Annex A Example of channel switching
39、 service (This annex forms an integral part of this Recommendation.) Every cable broadcasting service operator may have a different channel allocation, but in most cases, the channel allocation is divided into an upstream transmission frequency and a downstream transmission frequency. The downstream
40、 transmission frequency is further divided into analogue broadcasting, digital broadcasting and communication data transmission. For example, channel switching service in cable TV uses a 6 MHz channel bandwidth and 256 QAM. This supposes that several logical channels are included in a physical chann
41、el. The transmission data rates of a physical channel is about 38.8 Mbit/s. Therefore, if the frequency bandwidth of a channel is 8 MHz or uses 64 QAM or 1024 QAM, an additional analysis may be requested. Channel switching in digital broadcasting is the transmission of the subscribers selected chann
42、els only and not the unilateral transmission of all broadcasting channels. This is a service to increase the efficiency of frequency use by transmitting subscribers selected channels only and using other channel bands for communication service. Figure A.1 shows an example of switching in typical dig
43、ital cable broadcasting. In typical cable broadcasting, the broadcast channel band is distinguished from the communication channel band, and there are selected channels and non-selected channels of subscribers as shown in Figure A.1(a). The example in Figure A.1(c) shows only selected channels that
44、are re-multiplexed and redistributed and other channels are used as data over cable service interface specifications (DOCSIS) channel for data communication However, it is very difficult to implement switching system and operate channels in real time. Whenever a selected channel is changed in real t
45、ime, the channel should be re-multiplexed. So re-multiplexer for each physical channel is requested. Devices to input logical channel data to the physical channel are requested because logical data to each physical channel is continuously changed to currently selected channels. The data of signallin
46、g information and program specific information by re-multiplexing should be updated in real time as logical channel of physical channel is changed. Consideration should be given on how to improve the efficiency of frequency use by providing a system that implements broadcast channel switching withou
47、t introducing unnecessary complications. Figure A.2 shows how to increase the efficiency of frequency use by combining communication data with broadcasting data, and transmitting them to idle bandwidth by each channel, without transmitting those channels that were not selected. This does not need to
48、 re-multiplex broadcast channels transmitting after broadcast channel switching and also to change channel signalling information because physical channels transmitting broadcast channels are not changed. If adding communication data to idle bandwidth of the physical channel and transmitting them by
49、 transmitting only broadcasting data watched now from a physical channel through broadcast channel switching in real time against subscribers channel switching continuously, it is possible to get the same efficiency of frequency use. 6 Rec. ITU-T J.1105 (10/2016) Figure A.1 Figure A.2 Rec. ITU-T J.1105 (10/2016) 7 Bibliography b-ANSI/SCTE 133 2010 ANSI/SCTE 133 (2010), Downstream RF interface for Cable Modem Termination Systems. b-ANSI/SCTE 135-1 2008 ANSI/SCTE 135-1(2008), DOCSIS 3.0 Part 1: Physical Layer Specification. b-ANSI/SCTE 135-2 2008 ANS
