1、 INTERNATIONAL TELECOMMUNICATION UNION ITU-T J.112TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU Annex C(02/2002) SERIES J: CABLE NETWORKS AND TRANSMISSION OF TELEVISION, SOUND PROGRAMME AND OTHER MULTIMEDIA SIGNALS Interactive systems for digital television distribution Transmission systems for in
2、teractive cable television services Annex C: Data-over-cable service interface specifications: Radio-frequency interface specification using QAM technique ITU-T Recommendation J.112 Annex C ITU-T J-SERIES RECOMMENDATIONS CABLE NETWORKS AND TRANSMISSION OF TELEVISION, SOUND PROGRAMME AND OTHER MULTIM
3、EDIA SIGNALS General Recommendations J.1J.9 General specifications for analogue sound-programme transmission J.10J.19 Performance characteristics of analogue sound-programme circuits J.20J.29 Equipment and lines used for analogue sound-programme circuits J.30J.39 Digital encoders for analogue sound-
4、programme signals J.40J.49 Digital transmission of sound-programme signals J.50J.59 Circuits for analogue television transmission J.60J.69 Analogue television transmission over metallic lines and interconnection with radio-relay links J.70J.79 Digital transmission of television signals J.80J.89 Anci
5、llary digital services for television transmission J.90J.99 Operational requirements and methods for television transmission J.100J.109 Interactive systems for digital television distribution J.110J.129 Transport of MPEG-2 signals on packetised networks J.130J.139 Measurement of the quality of servi
6、ce J.140J.149 Digital television distribution through local subscriber networks J.150J.159 IPCablecom J.160J.179 Miscellaneous J.180J.199 Application for Interactive Digital Television J.200J.209 For further details, please refer to the list of ITU-T Recommendations. ITU-T Rec. J.112/Annex C (02/200
7、2) i ITU-T Recommendation J.112 Transmission systems for interactive cable television services Annex C Data-over-cable service interface specifications: Radio-frequency interface specification using QAM technique Summary This annex includes descriptions of 256-QAM for downstream and 16-QAM for upstr
8、eam in Physical Layer. These modulation functions enable cable television networks to transmit high speed programme data and IP Packets as well. However, the most significant change of this revised annex is an enhancement of MAC Layer the descriptions for QoS oriented services such as Voice over IP,
9、 Video over IP. The enhancement includes Extension of MAC Frame Format, Extension for QoS Control Function, Payload Header Suppression and Multicast Extension. Source Annex C to ITU-T Recommendation J.112 was revised by ITU-T Study Group 9 (2001-2004) and approved under the WTSA Resolution 1 procedu
10、re on 13 February 2002. Keywords must, must not, should, should not, may ii ITU-T Rec. J.112/Annex C (02/2002) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T
11、) 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 Assembly (WTSA), which meets every four yea
12、rs, 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 fall within ITU-Ts purview, the nece
13、ssary 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. INTELLECTUAL PROPERTY RIGHTS ITU draws attention to the
14、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 applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of
15、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 Recommendation. However, implementors are cautioned that this may not represent the latest inform
16、ation and are therefore strongly urged to consult the TSB patent database. ITU 2003 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.112/Annex C (02/2002) iii CONTENTS Page C.1 Scope 1 C.1.1 General
17、 Scope. 1 C.1.2 Background. 1 C.2 References. 3 C.3 Definitions and Abbreviations 5 C.3.1 Definitions 5 C.3.2 Abbreviations . 12 C.3.3 Conventions 13 C.4 Functional assumptions 14 C.4.1 Broadband access network . 14 C.4.2 Equipment assumptions 14 C.4.3 RF channel assumptions. 15 C.4.4 Transmission l
18、evels 17 C.4.5 Frequency inversion . 17 C.5 Communication protocols. 18 C.5.1 Protocol stack . 18 C.5.2 The MAC forwarder. 21 C.5.3 Network layer . 23 C.5.4 Above the network layer 25 C.5.5 Data link layer 25 C.5.6 Physical layer 26 C.6 Physical layer specification 26 C.6.1 Upstream. 26 C.6.2 Downst
19、ream 31 C.7 Downstream transmission convergence sublayer. 33 C.7.1 Introduction 34 C.7.2 MPEG packet format 34 C.7.3 MPEG header for Annex C/J.112 data-over-cable. 34 C.7.4 MPEG payload for Annex C/J.112 data-over-cable. 35 C.7.5 Interaction with the MAC sublayer 35 C.7.6 Interaction with the physic
20、al layer . 37 C.7.7 MPEG header synchronization and recovery. 37 C.8 Media access control specification . 37 C.8.1 Introduction 37 iv ITU-T Rec. J.112/Annex C (02/2002) Page C.8.2 MAC frame formats . 39 C.8.3 MAC management messages . 57 C.9 Media access control protocol operation 99 C.9.1 Upstream
21、bandwidth allocation 99 C.9.2 Support for multiple channels 106 C.9.3 Timing and synchronization. 106 C.9.4 Upstream transmission and contention resolution 108 C.9.5 Data link encryption support 110 C.10 Quality of Service for video it is 4 MHz). C.3.1.17 classifier: Set of criteria used for packet
22、matching according to TCP, UDP, IP, LLC, and/or 802.1P/Q packet fields. A classifier maps each packet to a Service Flow. A Downstream Classifier is used by the CMTS to assign packets to downstream service flows. An Upstream Classifier is used by the CM to assign packets to upstream service flows. C.
23、3.1.18 Composite Second Order Beat (CSO): The peak of the average level of distortion products due to second-order non-linearities in cable system equipment. C.3.1.19 Composite Triple Beat (CTB): The peak of the average level of distortion components due to third-order non-linearities in cable syste
24、m equipment. C.3.1.20 cross-modulation: Form of television signal distortion where modulation from one or more television channels is imposed on another channel or channels. C.3.1.21 customer: See End User (C.3.1.29). C.3.1.22 Customer Premises Equipment (CPE): Equipment at the end users premises; M
25、AY be provided by the end user or the service provider. C.3.1.23 data link layer: Layer 2 in the Open System Interconnection (OSI) architecture; the layer that provides services to transfer data over the transmission link between open systems. C.3.1.24 distribution hub: Location in a cable televisio
26、n network which performs the functions of a Headend for customers in its immediate area, and which receives some or all of its television program material from a Master Headend in the same metropolitan or regional area. C.3.1.25 downstream: In cable television, the direction of transmission from the
27、 headend to the subscriber. C.3.1.26 drop cable: Coaxial cable that connects to a residence or service location from a directional coupler (tap) on the nearest coaxial feeder cable. C.3.1.27 Dynamic Host Configuration Protocol (DHCP): Internet protocol used for assigning network-layer (IP) addresses
28、. C.3.1.28 dynamic range: The ratio between the greatest signal power that can be transmitted over a multichannel analog transmission system without exceeding distortion or other performance limits, and the least signal power that can be utilized without exceeding noise, error rate or other performa
29、nce limits. C.3.1.29 end user: Human being, organization, or telecommunication system that accesses the network in order to communicate via the services provided by the network. C.3.1.30 errored second: Any 1-second interval containing at least one bit error. ITU-T Rec. J.112/Annex C (02/2002) 7 C.3
30、.1.31 feeder cable: Coaxial cables that run along streets within the served area and connect between the individual taps which serve the customer drops. C.3.1.32 Fiber Distributed Data Interface (FDDI): Fiber-based LAN standard. C.3.1.33 fiber node: Point of interface between a fiber trunk and the c
31、oaxial distribution. C.3.1.34 forward channel: The direction of RF signal flow away from the headend toward the end user; equivalent to Downstream. C.3.1.35 group delay: The difference in transmission time between the highest and lowest of several frequencies through a device, circuit or system. C.3
32、.1.36 guard time: Minimum time allocated between bursts in the upstream referenced from the symbol center of the last symbol of a burst to the symbol center of the first symbol of the following burst. The guard time be at least the duration of five symbols plus the maximum system timing error. C.3.1
33、.37 Harmonic Related Carrier (HRC): Method of spacing television channels on a cable television system in exact 6 MHz increments, with all carrier frequencies harmonically related to a common reference. C.3.1.38 headend: The central location on the cable network that is responsible for injecting bro
34、adcast video and other signals in the downstream direction. See also Master Headend, Distribution Hub. C.3.1.39 header: Protocol control information located at the beginning of a protocol data unit. C.3.1.40 High Frequency (HF): Used in this annex to refer to the entire subsplit (5 MHz to 30 MHz) an
35、d extended subsplit (5 MHz to 42 MHz) band used in reverse channel communications over the cable television network. C.3.1.41 high return: Frequency division scheme that allows bi-directional traffic on a single coaxial cable. Reverse channel signals propagate to the headend above the downstream pas
36、sband. C.3.1.42 hum modulation: Undesired modulation of the television visual carrier by the fundamental or low-order harmonics of the power supply frequency, or other low-frequency disturbances. C.3.1.43 Hybrid Fiber/Coax (HFC) system: Broadband bidirectional shared-media transmission system using
37、fiber trunks between the headend and the fiber nodes, and coaxial distribution from the fiber nodes to the customer locations. C.3.1.44 Incremental Related Carriers (IRC): Method of spacing NTSC television channels on a cable television system in which all channels except 5 and 6 correspond to the s
38、tandard channel plan, used to reduce composite triple beat distortions. C.3.1.45 Institute of Electrical and Electronic Engineers (IEEE): Voluntary organization which, among other things, sponsors standards committees and is accredited by the American National Standards Institute. C.3.1.46 Internati
39、onal Electrotechnical Commission (IEC): International standards body. C.3.1.47 International Organization for Standardization (ISO): International standards body, commonly known as the International Standards Organization. C.3.1.48 Internet Control Message Protocol (ICMP): Internet network-layer pro
40、tocol. C.3.1.49 Internet Engineering Task Force (IETF): Body responsible, among other things, for developing standards used in the Internet. C.3.1.50 Internet Group Management Protocol (IGMP): Network-layer protocol for managing multicast groups on the Internet. 8 ITU-T Rec. J.112/Annex C (02/2002)
41、C.3.1.51 impulse noise: Noise characterized by non-overlapping transient disturbances. C.3.1.52 information element: The fields that make up a MAP and define individual grants, deferred grants, etc. C.3.1.53 Internet Protocol (IP): Internet network-layer protocol. C.3.1.54 interval usage code (IUC):
42、 Field in MAPs and UCDs to link burst profiles to grants. C.3.1.55 latency: The time, expressed in quantity of symbols, taken for a signal element to pass through a device. C.3.1.56 layer: Subdivision of the Open System Interconnection (OSI) architecture, constituted by subsystems of the same rank.
43、C.3.1.57 Local Area Network (LAN): Non-public data network in which serial transmission is used for direct data communication among data stations located on the users premises. C.3.1.58 Logical Link Control (LLC) procedure: In a local area network (LAN) or a Metropolitan Area Network (MAN), that par
44、t of the protocol that governs the assembling of data link layer frames and their exchange between data stations, independent of how the transmission medium is shared. C.3.1.59 master headend: Headend which collects television program material from various sources by satellite, microwave, fiber and
45、other means, and distributes this material to Distribution Hubs in the same metropolitan or regional area. A Master Headend MAY also perform the functions of a Distribution Hub for customers in its own immediate area. C.3.1.60 Mean Time to Repair (MTTR): In cable television systems, the MTTR is the
46、average elapsed time from the moment a loss of RF channel operation is detected up to the moment the RF channel operation is fully restored. C.3.1.61 Media Access Control (MAC) address: The “built-in“ hardware address of a device connected to a shared medium. C.3.1.62 Media Access Control (MAC) proc
47、edure: In a subnetwork, that part of the protocol that governs access to the transmission medium independent of the physical characteristics of the medium, but taking into account the topological aspects of the subnetworks, in order to enable the exchange of data between nodes. MAC procedures includ
48、e framing, error protection, and acquiring the right to use the underlying transmission medium. C.3.1.63 Media Access Control (MAC) sublayer: The part of the data link layer that supports topology-dependent functions and uses the services of the Physical Layer to provide services to the logical link
49、 control (LLC) sublayer. C.3.1.64 micro-reflections: Echoes in the forward transmission path due to departures from ideal amplitude and phase characteristics. C.3.1.65 mid split: Frequency division scheme that allows bidirectional traffic on a single coaxial cable. Reverse channel signals propagate to the headend. Forward path signals go from the headend. C.3.1.66 mini-slot: “Mini-slot“ is an integer multiple of 64/9.216 microsecond increments. The relationship between mini-slots, bytes and time ticks is described in C.9.3.4. C.3.1.67 Moving Picture Experts Group (MPEG
