1、 INTERNATIONAL TELECOMMUNICATION UNION ITU-T J.184 TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (03/2001) SERIES J: CABLE NETWORKS AND TRANSMISSION OF TELEVISION, SOUND PROGRAMME AND OTHER MULTIMEDIA SIGNALS Miscellaneous Digital broadband delivery system: Out-of-band transport ITU-T Recommendati
2、on J.184 (Formerly CCITT Recommendation) ITU-T J-SERIES RECOMMENDATIONS CABLE NETWORKS AND TRANSMISSION OF TELEVISION, SOUND PROGRAMME AND OTHER MULTIMEDIA SIGNALS General Recommendations J.1J.9 General specifications for analogue sound-programme transmission J.10J.19 Performance characteristics of
3、analogue sound-programme circuits J.20J.29 Equipment and lines used for analogue sound-programme circuits J.30J.39 Digital encoders for analogue sound-programme signals J.40J.49 Digital transmission of sound-programme signals J.50J.59 Circuits for analogue television transmission J.60J.69 Analogue t
4、elevision transmission over metallic lines and interconnection with radio-relay links J.70J.79 Digital transmission of television signals J.80J.89 Ancillary digital services for television transmission J.90J.99 Operational requirements and methods for television transmission J.100J.109 Interactive s
5、ystems for digital television distribution J.110J.129 Transport of MPEG-2 signals on packetised networks J.130J.139 Measurement of the quality of service J.140J.149 Digital television distribution through local subscriber networks J.150J.159 IPCablecom J.160J.179 Miscellaneous J.180J.199 Application
6、 for Interactive Digital Television J.200J.209 For further details, please refer to the list of ITU-T Recommendations. ITU-T J.184 (03/2001) i ITU-T Recommendation J.184 Digital broadband delivery system: Out-of-band transport Summary This Recommendation specifies the Physical Layer and the Data Lin
7、k Layer (including the MAC Layer) of two out-of-band cable system transport protocols, denoted as Mode A and Mode B, which are currently in operation. Source ITU-T Recommendation J.184 was prepared by ITU-T Study Group 9 (2001-2004) and approved under the WTSA Resolution 1 procedure on 9 March 2001.
8、 ITU-T J.184 (03/2001) iiFOREWORD 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, operating
9、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, produce
10、 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 this R
11、ecommendation, the expression “Administration“ is used for conciseness to indicate both a telecommunication 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
12、 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 approval of this Recommendat
13、ion, 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 TSB patent database. ITU 200
14、2 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 ITU. ITU-T J.184 (03/2001) iii CONTENTS Page 1 Scope. 1 2 Definitions 1 3 Requirements 2 3.
15、1 Forward Data Channels (FDC) . 2 3.2 Reverse Data Channels (RDC) . 2 Annex A Digital broadband delivery system: Out-of-band transport Mode A . 3 A.1 Introduction. 3 A.2 Acronyms 3 A.3 References. 4 A.4 Out-of-band system specifications 5 A.5 Physical layer specification 5 A.5.1 Physical layer For O
16、OB transmission . 5 A.5.2 Physical layer for return-path transmission. 11 A.5.3 Extended practice for return-path transmission (Informative) 14 A.6 Data link layer. 15 A.6.1 Application PDU Processing. 15 A.6.2 Link layer headers/trailers . 17 A.6.3 Segmentation and reassembly . 19 A.6.4 MAC informa
17、tion transport. 20 A.6.5 MAC signalling messages . 23 Annex B Digital broadband delivery system: Out-of-band transport Mode B 39 B.1 Introduction. 39 B.1.1 Revision history. 39 B.1.2 Acronyms. 39 B.1.3 References . 41 B.2 DAVIC out-of-band and upstream signalling. 42 B.2.1 Downstream physical interf
18、ace specification 43 B.2.2 Upstream physical interface specification. 56 B.2.3 Media access control functionality 64 ITU-T J.184 (03/2001) 1 ITU-T Recommendation J.184 Digital broadband delivery system: Out-of-band transport 1 Scope This Recommendation describes the Physical Layer and Data Link Laye
19、r (including the MAC Layer) used in cable networks which employ an Out-Of-Band channel architecture. There are two methods used for Out-of-band (OOB) transport in cable systems. These two methods are denoted as Mode A and Mode B, respectively. Their detailed specifications are described in this Reco
20、mmendation. 2 Definitions This Recommendation defines the following terms: 2.1 forward data channel: A data channel carried from the headend to the terminal device in a modulated channel at a rate of 1.544 to 3.088 Mbit/s. The FDC carries IP traffic only for: Conditional access for analogue signals.
21、 Entitlement management messages for digital signals. General messaging. Application download. PC data services. Variable bit rate (VBR) download. Broadcast data. Network management. 2.2 reverse data channel: A data channel transmitted from the terminal device to the headend in a modulated channel a
22、t a rate of 0.256 to 3.088 Mbit/s. The RDC carries IP traffic only for: Messaging. Personal computer data services. Network management. 2.3 upstream: Transmission from terminal device to Headend. 2.4 downstream: Transmission from Headend to terminal device. 2.5 (OOB) Out-of-band: Outside of the prog
23、ramming channels band. The OOB channels provide communication channels between the network and the terminal. 2.6 QPSK/differential coding: A special QPSK system that uses differential encoding scheme to resolve the 90 ambiguity in the detection of the QPSK signal at the demodulator. ITU-T J.184 (03/
24、2001) 23 Requirements In the implementation of digital services over cable television networks, there is a need for messaging and signalling between the cable system headend and the subscriber terminal device in both the forward channel in the downstream direction and the reverse channel in the upst
25、ream direction. These functions are implemented through the use of appropriate transport protocols and of an auxiliary transport stream of adequate data capacity. This auxiliary data stream can be transported in the multiplex that carries the main transport stream for the main programme channel (in-
26、band transmission). It can also be transported as a separate data channel that fits in the lower part of the frequency spectrum, below the one allocated to programme channels in cable television systems (out-of-band transmission). This Recommendation describes out-of-band transport protocols for mes
27、saging and signalling between the cable system headend and subscriber terminal devices in the forward data channel in the downstream direction and the reverse data channel in the upstream direction. Two alternatives are described for the out-of-band transport protocol: Mode A and Mode B. They are sp
28、ecified in Annexes A and B, respectively. Each mode consists of specifications for the forward data channel in the downstream direction and the reverse data channel in the upstream direction. 3.1 Forward Data Channels (FDC) Mode A Forward Data Channel supports a data rate of 2.048 Mbit/s and Mode B
29、supports data rates of 1.544 and 3.088 Mbit/s. Table 1 shows the lower layer protocol stacks for these out-of-band FDCs. It should be noted that in Mode B, time critical aspects of the Media Access Control (MAC) protocol sublayer are implemented in the SL-ESF Frame Payload Structure. The remainder o
30、f the MAC sublayer is implemented via the MAC message in the Payload. Table 1/J.184 Out-of-band forward data channel lower layer protocols Mode A Mode B Payload Payload Data Link Layer ATM Cell Format MAC Sublayer: MAC Packet MPEG-2 TS OOB FDC Lower Layer Protocols Physical Layer: Randomizer Reed-So
31、lomon Interleaving QPSK/differential coding Link/Physical Layer: Reed-Solomon Interleaving SL-ESF Frame Payload Structure SL-ESF Format Randomizer QPSK/differential coding 3.2 Reverse Data Channels (RDC) The RDCs may be present anywhere within the network-supported passband. There are two alternativ
32、es for the out-of-band RDCs as defined in Mode A and Mode B. Table 2 shows the lower layer protocol stacks for the out-of-band RDCs. ITU-T J.184 (03/2001) 3 Table 2/J.184 Out-of-band reverse data channel lower layer protocols Mode A Mode B Payload Payload Data link Layer/AAL5 Data link Layer/AAL5 MA
33、C Sublayer: MAC Packet Sublayer ATM Cell Format MAC Sublayer: MAC Signalling Message ATM Cell Format OOB RDC Lower Layer Protocols Physical Layer: Randomizer Reed-Solomon Burst QPSK/differential coding Physical Layer: Reed-Solomon Randomizer Burst QPSK/differential coding Detailed protocols for FDCs
34、 and RDCs for Mode A and B are specified in Annexes A and B, respectively. ANNEX A Digital broadband delivery system: Out-of-band transport Mode A A.1 Introduction This annex describes a transport protocol used in the cable network which employs the Out-Of-Band channel architecture. The physical lay
35、er is specified for the transport mechanism for the Out-Of-Band (OOB) cable system currently in practice in North America. Specifications of the MAC Layer and the Link Layer are also provided as “Informative sections“. These Informative sections may be updated in the future, recognizing the potentia
36、l adaptation of DOCSIS MAC Layer Specification 3. A.2 Acronyms This annex uses the following acronyms: AAL ATM Adaptation Layer ATM Asynchronous Transfer Mode AWGN Additive White Gaussian Noise BW BandWidth CBD Connection Block Descriptor CRC Cyclic Redundancy Check CW ClockWise DAVIC Digital Audio
37、Video Council DCM Default Configuration Message DLL Data Link Layer DOCSIS Data Over Cable System Interface Specification FEC Forward Error Correction GF Galois Field ITU-T J.184 (03/2001) 4IB In-Band IBTM In-Band Timebase Message ID IDentification IE Information Element IP Internet Protocol LFSR Li
38、near Feedback Shift Register MAC Media Access Control MAP Map of Bandwidth Allocation MCNS Multimedia Cable Network System MPEG Moving Picture Experts Group Msymb/s Mega symbols per second NRC Network Related Control OBTM Out-of-Band Timebase Message OOB Out-of-Band PDU Protocol Data Unit PER Packet
39、 Error Rate PN Pseudo-random Number PT Payload Type QAM Quadrature Amplitude Modulation QPSK Quadrature Phase Shift Keying R-S Reed-Solomon Coding SDU Service Data Unit SER Symbol Error Rate TDMA Time Division Multiple Access TS Transport Stream UPM UPstream MAC A.3 References Normative references T
40、he 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 revision; users of th
41、is 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. ITU-T J.184 (03/2001) 5 Normative reference list 1 IEEE
42、0802-1990, Local and Metropolitan Area Networks: Overview and Architecture, and ISO/IEC 10039:1991, Information technology Open Systems Interconnection Local area networks Medium Access Control (MAC) service definition. 2 ITU-T H.222.0 (2000) | ISO/IEC 13818-1:2000, Information technology Generic co
43、ding of moving pictures and associated audio information: Systems. Bibliography 3 CableLabs: Data-Over-Cable-Service Interface Specifications (DOCSIS): Radio Frequency Interface Specification, SP-RFIv1.1.I01-990311 (1999). . 4 Digital Audio Visual Council 1.4 Specification Part 8, Lower Layer Protoc
44、ols and Physical Interfaces. (http:/www.davic.org/.) 5 CLARK (G.C.), CAIN (J.B.): Error-Correction Coding for Digital Communications, Plenum Press, (1981). A.4 Out-of-band system specifications This annex specifies the Physical Layer and the Data Link Layer (including the MAC Layer) of the Out-of-Ba
45、nd cable system transport. Clause A.5 describes the Physical Layer protocol. Clause A. 6 describes the Data Link Layer protocol. The MAC Layer specification refers to the DOCSIS 3. However, not all DOCSIS specifications for the MAC Layer are required. The minimum set is specified. Future enhancement
46、s toward full DOCSIS compliance might be expected. This annex assumes that the reader has some: 1) fundamental understanding of the conventional cable frequency plan; and 2) familiarity with the Ethernet specification and the Reed-Solomon Coding of Error Correction Schemes. Also, use of the referenc
47、es denoted in A.3 is highly recommended for a full understanding of this annex. A.5 Physical layer specification This clause describes the physical layer of the Out-Of-Band downstream and upstream channels. A.5.1 Physical layer For OOB transmission The aggregate information rate of the Out-Of-Band (
48、OOB) channel is 2.048 Mbit/s. Up to 1.544 Mbit/s may be utilized for access control and other control information as well as application data, application program downloads, program guides, etc. The OOB data channel provides continuous communication from a Headend to Digital Terminals. The Digital T
49、erminal typically remains powered-up even when it is in the “off“ state. The OOB channel remains active independent of the tuned video channel, whether the received TV channel is analogue or digital, and whether the Digital Terminal box is turned “on“ or “off“. Thus, whenever the Digital Terminal connected to the coaxial cable and AC power, the OOB channel is active for downstream communication. A.5.1.1 OOB transmission format Table A.1 summarizes the physical attributes
