1、 International Telecommunication Union ITU-T J.210 TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (11/2006) SERIES J: CABLE NETWORKS AND TRANSMISSION OF TELEVISION, SOUND PROGRAMME AND OTHER MULTIMEDIA SIGNALS Interactive systems for digital television distribution Downstream RF interface for cable
2、 modem termination systems ITU-T Recommendation J.210 ITU-T Rec. J.210 (11/2006) i ITU-T Recommendation J.210 Downstream RF interface for cable modem termination systems Summary This Recommendation defines the downstream radio frequency interface (DRFI) specifications for: an edgeQAM (EQAM) modular
3、device; or an integrated cable modem termination system (CMTS) with multiple downstream channels per RF port; or an integrated CMTS beyond DOCSIS 2.0. Source ITU-T Recommendation J.210 was approved on 29 November 2006 by ITU-T Study Group 9 (2005-2008) under the ITU-T Recommendation A.8 procedure. i
4、i ITU-T Rec. J.210 (11/2006) FOREWORD The International Telecommunication Union (ITU) is the United Nations 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, operat
5、ing 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 meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, pro
6、duce 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-Ts purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. NOTE In th
7、is Recommendation, the expression “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. int
8、eroperability 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“ and the negative equivalents are used to express requirements. The use of such words does not suggest
9、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 involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence
10、, 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 Recommendation, ITU had not received notice of intellectual property, protected by patents, which may b
11、e required to implement this 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 2007 All rights reserved. No part of this publication may be re
12、produced, by any means whatsoever, without the prior written permission of ITU. ITU-T Rec. J.210 (11/2006) iii CONTENTS Page 1 Scope 1 1.1 Scope 1 1.2 World wide use. 1 2 References. 2 2.1 Normative references 2 2.2 Informative References 3 2.3 Reference acquisition. 3 3 Terms and definitions . 3 4
13、Acronyms, abbreviations and conventions. 5 4.1 Acronyms and abbreviations 5 4.2 Conventions 5 5 Functional assumptions 6 5.1 Broadband access network . 6 5.2 Equipment assumptions 6 5.3 Downstream plant assumptions 7 6 Physical media dependent sublayer specification. 8 6.1 Scope 8 6.2 EdgeQAM (EQAM)
14、 differences from CMTS 9 6.3 Downstream 9 7 Downstream transmission convergence sublayer. 18 7.1 Introduction 18 7.2 MPEG packet format 18 7.3 MPEG header for DOCSIS data-over-cable. 19 7.4 MPEG payload for DOCSIS data-over-cable. 19 7.5 Interaction with the MAC sublayer 20 7.6 Interaction with the
15、physical layer . 21 Annex A Additions and modifications for European specification 22 A.1 Scope and purpose 22 A.2 References 22 A.3 Terms and definitions. 22 A.4 Acronyms and abbreviations 22 A.5 Functional assumptions 22 A.6 Physical media dependent sublayer specification 24 A.7 Downstream transmi
16、ssion convergence sublayer. 31 Annex B Additions and modifications for Japanese specification . 32 B.1 Scope and purpose 32 B.2 References 32 B.3 Terms and definitions. 32 iv ITU-T Rec. J.210 (11/2006) Page B.4 Acronyms and abbreviations 32 B.5 Functional assumptions 32 B.6 Physical media dependent
17、sublayer specification 33 B.7 Downstream transmission convergence sublayer. 41 ITU-T Rec. J.210 (11/2006) 1 ITU-T Recommendation J.210 Downstream RF interface for cable modem termination systems 1 Scope 1.1 Scope The DOCSIS Rec. J.112 and ITU-T J.122 define the requirements for the two fundamental c
18、omponents that comprise a high-speed data-over-cable system: the cable modem (CM) and the cable modem termination system (CMTS). This Recommendation provides physical layer requirements for CMTS transmitters in the DOCSIS architecture. It applies to head-end components built according to the M-CMTS
19、architecture (ITU-T J.212 and ITU-T J.211) as well as integrated CMTS systems. This Recommendation defines the downstream radio frequency interface (DRFI) specifications for: an edgeQAM (EQAM) modular device; or an integrated cable modem termination system (CMTS) with multiple downstream channels pe
20、r RF port; or an integrated CMTS beyond DOCSIS 2.0. 1.2 World wide use There are differences in the cable spectrum planning practices adopted for different networks in the world. Therefore three options for physical layer technology are included, which have equal priority and are not required to be
21、interoperable. One technology option is based on the downstream multi-program television distribution that is deployed in the Americas using 6 MHz channels. The second technology option is based on the corresponding European multi-program television distribution using 8 MHz channels. The third techn
22、ology option is based on the corresponding Japanese multi-program television distribution using 6 MHz channels. All options have the same status, notwithstanding that the document structure does not reflect this equal priority. The first of these options is defined in clauses 5, 6, 7, whereas the se
23、cond and the third are defined by replacing the content of those clauses with the content of Annexes A and B respectively. Correspondingly, ITU-T J.83-B and CEA-542-B apply only to the first option, ETSI EN 300 429 applies only to the second, and ITU-T J.83-C applies only to the third option. Compli
24、ance with this Recommendation requires compliance with at least one of these implementations, not necessarily with more than one. It is not required that equipment built to one option shall interoperate with equipment built to the others. A DRFI-compliant device may be a single-channel only device,
25、or it may be a multiple-channel device capable of generating one or multiple downstream RF carriers simultaneously on one RF output port. An EQAM may be a module of a modular cable modem termination system (M-CMTS) and be used for delivering a high-speed data service or it may serve as a component o
26、f a digital video or video-on-demand (VoD) system, delivering high quality digital video to subscribers. These specifications are crafted to enable an EQAM to be used without restriction in either or both service delivery scenarios simultaneously. “Simultaneous“ in the early deployments means that i
27、f a RF output port has multiple QAM channels, some channel(s) may be delivering high-speed data while some other channel(s) may be delivering digital video. This specification enables future uses, wherein a single QAM channel may share bandwidth between high-speed data and digital video in the same
28、MPEG transport stream. Conceptually, an EQAM will accept input via an Ethernet link, integrate the incoming data into an MPEG transport stream, modulate one of a plurality of RF carriers, per these specifications, and deliver the carrier to a single RF output connector shared in common with all modu
29、lators. 2 ITU-T Rec. J.210 (11/2006) Conceivably, a single EQAM RF channel could be used for data and video simultaneously. The reason that an EQAM RF channel can be used for either is that both digital video and DOCSIS data downstream channels are based on ITU-T J.83-B for cable networks in the Ame
30、ricas, ETSI EN 300 429 for cable networks deployed in Europe and ITU-T J.83-C for cable networks in Japan. On downstream channels complying to ITU-T J.83-B, typically, the only difference between an EQAM RF channel operating in a video mode and an EQAM RF channel operating in DOCSIS data mode is the
31、 interleaver depth (see clauses 6.3.1 and 6.3.3). DOCSIS data runs in a low latency mode using a shallow interleaver depth at the cost of some burst protection. DOCSIS data can do this because if a transmission error occurs, the higher layer protocols will request retransmission of the missing data.
32、 For video, the sequence of frames in the program is both time sensitive and order sensitive and cannot be retransmitted. For this reason, video uses a deeper interleaver depth to provide more extensive burst protection and deliver more of the program content without loss. The penalty video pays is
33、in latency. The entire program content is delayed by a few milliseconds, typically, and is invisible to the viewers of the program. The conflicting demands for interleaver depth are what prevent a single EQAM RF channel from being used optimally for video and DOCSIS data simultaneously. A traditiona
34、l integrated CMTS, however, is used solely for DOCSIS data. 2 References 2.1 Normative 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
35、indicated were valid. All Recommendations and other references are subject to revision; 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
36、-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 a Recommendation. ITU-T H.222.0 ITU-T Recommendation H.222.0 (2006) | ISO/IEC 13818-1:2006, Information technology Generic coding of moving pic
37、tures and associated audio information: Systems. ITU-T J.83-B ITU-T Recommendation J.83 (1997), Digital multi-programme systems for television, sound and data services for cable distribution. Annex B: Digital multi-programme System B. ITU-T J.83-C ITU-T Recommendation J.83 (1997), Digital multi-prog
38、ramme systems for television, sound and data services for cable distribution. Annex C: Digital multi-programme System C. ITU-T J.122 ITU-T Recommendation J.122 (2002), Second-generation transmission systems for interactive cable television services IP cable modems. ITU-T J.211 ITU-T Recommendation J
39、.211 (2006), Timing interface for cable modem termination systems. ETSI EN 300 429 ETSI EN 300 429 V1.2.1 (1998), Digital Video Broadcasting (DVB); Framing structure, channel coding and modulation for cable systems. IEC 60169-24 IEC 60169-24 (1991), Radio-frequency connectors Part 24: Radio-frequenc
40、y coaxial connectors with screw coupling, typically for use in 75 ohm cable distribution systems (Type F). ITU-T Rec. J.210 (11/2006) 3 2.2 Informative References ITU-T J.212 ITU-T Recommendation J.212 (2006), Downstream external physical layer interface for modular cable modem termination systems.
41、NSI Cable Modem Termination System Network Side Interface, SP-CMTS-NSI-I01-960702, 2 July 1996, Cable Television Laboratories, Inc. M-OSSI Modular CMTS Operations Support System Interface, CM-SP-M-OSSI-I02-051209, 9 December 2005, Cable Television Laboratories, Inc. CEA-542-B CEA-542-B: CEA Standard
42、: Cable Television Channel Identification Plan, July 2003. CMCI Cable Modem to Customer Premises Equipment Interface, CM-SP-CMCI-I10-050408, 8 April 2005, Cable Television Laboratories, Inc. ERMI Edge Resource Manager Interface, CM-SP-ERMI-I02-051209, 9 December 2005, Cable Television Laboratories,
43、Inc. Article 23-(1) Regulations for Enforcement of the Cable Television Article 23-(1), Ministry of Internal Affairs and Communications (MIC), Japan. 2.3 Reference acquisition Cable Television Laboratories, Inc., http:/ EIA: Electronic Industries Alliance, http:/www.eia.org/new_contact/ ETSI: Europe
44、an Telecommunications Standards Institute, http:/www.etsi.org/services_products/freestandard/home.htm ITU: International Telecommunication Union (ITU), http:/www.itu.int/home/contact/index.html ISO: International Organization for Standardization (ISO), http:/www.iso.org/iso/en/xsite/contact/contact.
45、html MIC: Ministry of Internal Affairs and Communications (MIC), http:/www.soumu.go.jp/joho_tsusin/eng/index.html 3 Terms and definitions This Recommendation defines the following terms: 3.1 ceiling (ceil): The ceiling function rounds a number up to the nearest integer or nearest multiple of signifi
46、cance. Use: Ceiling (number, significance). 3.2 cable modem (CM): A modulator-demodulator at subscriber locations intended for use in conveying data communications on a cable television system. 3.3 customer premises equipment (CPE): Equipment at the end users premises; may be provided by the service
47、 provider. 3.4 carrier-to-noise ratio (C/N or CNR): The ratio of signal power to noise power in a defined measurement bandwidth. For digital modulation, CNR = E s /N 0 , the energy-per symbol to noise-density ratio; the signal power is measured in the occupied bandwidth, and the noise power is norma
48、lized to the modulation-rate bandwidth. For analog NTSC video modulation, the noise measurement bandwidth is 4 MHz. 3.5 decibels (dB): Ratio of two power levels expressed mathematically as dB = 10log 10 (P OUT /P IN ). 4 ITU-T Rec. J.210 (11/2006) 3.6 decibel-millivolt (dBmV): Unit of RF power expre
49、ssed in decibels relative to 1 millivolt over 75 ohms, where dBmV = 20log 10 (value in mV/1 mV). 3.7 decibel-microvolt (dBV): Unit of RF power expressed in decibels relative to 1 microvolt over 75 ohms, where dBV = 20log 10 (value in V/1 V). 3.8 Electronic Industries Alliance (EIA): A voluntary body of manufacturers which, among other activities, prepares and publishes standards. 3.9 edgeQAM modulator (EQAM): A head end or hub device that receives packets of digital video or dat
