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.382 TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (03/2018) SERIES J: CABLE NETWORKS AND TRANSMISSION OF TELEVISION, SOUND PROGRAMME AND OTHER MULTIMEDIA SIGNALS Digital transmission of television signals Part 3 Advance
2、d digital downstream transmission systems for television, sound and data services for cable distribution Recommendation ITU-T J.382 Rec. ITU-T J.382 (03/2018) i Recommendation ITU-T J.382 Advanced digital downstream transmission systems for television, sound and data services for cable distribution
3、Summary Recommendation ITU-T J.382 provides specifications that should be considered for advanced digital cable downstream transmission technologies to provide high spectral efficiency schemes saving transmission resources for downstream in hybrid fibre coax (HFC) based networks. This Recommendation
4、 covers the common definition of framing structure, channel coding and modulation for television, sound and data services including high quality broadcast and multicast services distributed through HFC based networks. History Edition Recommendation Approval Study Group Unique ID* 1.0 ITU-T J.382 201
5、4-01-13 9 11.1002/1000/12104 2.0 ITU-T J.382 2018-03-16 9 11.1002/1000/13563 Keywords Advanced transmission systems, cable distribution, DVB-C2, HFC, OFDM. * To access the Recommendation, type the URL http:/handle.itu.int/ in the address field of your web browser, followed by the Recommendations uni
6、que ID. For example, http:/handle.itu.int/11.1002/1000/11830-en. ii Rec. ITU-T J.382 (03/2018) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunic
7、ation 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 Assembly
8、 (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 f
9、all 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 this
10、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 RIGHTSITU draws attention to the possibility that the practice or implementation of this Reco
12、mmendation 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 ap
13、proval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be 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 TS
14、B patent database at http:/www.itu.int/ITU-T/ipr/. ITU 2018 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. Rec. ITU-T J.382 (03/2018) iii Table of Contents Page 1 Scope . 1 2 References . 1 3 Definitions 1 3.1
15、 Terms defined elsewhere 1 3.2 Terms defined in this Recommendation . 1 4 Abbreviations and acronyms 1 5 Conventions 3 6 Advanced digital downstream transmission systems for cable distribution . 3 6.1 System concept . 3 6.2 Specifications of advanced digital downstream transmission systems 4 Appendi
16、x I A digital video broadcasting (DVB); Frame structure channel coding and modulation for a second generation digital transmission system for cable systems (DVB-C2) . 6 I.1 Introduction 6 I.2 Main building blocks of a DVB-C2 modulator 7 I.3 Summary of the key DVB-C2 features 9 I.4 Cable system conce
17、pt . 10 Bibliography. 12 iv Rec. ITU-T J.382 (03/2018) Introduction As the demand for high quality broadcast and multicast services from the consumers side is increasing, cable operators are diligently researching more efficient ways to transmit those services through hybrid fibre coax (HFC) based n
18、etworks. Modulation and coding schemes for global use in cable industry are based on b-ITU-T J.83, which was developed and deployed in the 1990s. These technologies, specified in b-ITU-T J.83, can support up to 38 Mbit/s per 6 MHz channel when using a 256 quadrature amplitude modulation (QAM) modula
19、tion scheme and thus do not serve demands for advanced digital downstream transmission systems. In the near future, advanced digital transmission systems including enhanced coding and modulation, can replace digital cable transmission systems defined in b-ITU-T J.83. Rec. ITU-T J.382 (03/2018) 1 Rec
20、ommendation ITU-T J.382 Advanced digital downstream transmission systems for television, sound and data services for cable distribution 1 Scope The scope of this Recommendation is to define a globally common specification for framing structure, channel coding and modulation schemes for television, s
21、ound and data services including high quality broadcast and multicast services for downstream transmission distributed through hybrid fibre coax (HFC) based networks to provide high spectral efficiency. This Recommendation will contribute to the development of common products for cable broadcast and
22、 telecommunication downstream physical layer (PHY). The specifications included in this Recommendation are based on the requirements defined in ITU-T J.381. 2 References The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute prov
23、isions of this Recommendation. At the time of publication, the editions 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 Recommendati
24、ons and other references listed below. A list of the currently valid ITU-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 J.381 Recommendation ITU-T J.381 (2012), Requir
25、ements for advanced digital transmission technologies. ETSI EN 302 769 ETSI EN 302 769 V1.3.1 (2015), Digital Video Broadcasting (DVB) Frame structure channel coding and modulation for a second generation digital transmission system for cable systems (DVB-C2). 3 Definitions 3.1 Terms defined elsewhe
26、re This Recommendation uses the following term defined elsewhere: 3.1.1 HFC-based networks ITU-T J.381: HFC-based networks include legacy cable networks such as hybrid fibre coax; recent technology deployments such as radio frequency over glass (RFoG) and cable network technologies that may be deplo
27、yed in the near future. 3.2 Terms defined in this Recommendation None. 4 Abbreviations and acronyms This Recommendation uses the following abbreviations and acronyms: 16-QAM 16-ary Quadrature Amplitude Modulation 64-QAM 64-ary Quadrature Amplitude Modulation 256-QAM 256-ary Quadrature Amplitude Modu
28、lation 2 Rec. ITU-T J.382 (03/2018) 1024-QAM 1024-ary Quadrature Amplitude Modulation 4096-QAM 4096-ary Quadrature Amplitude Modulation ACM Adaptive Coding and Modulation ADC Analogue-to-Digital Converter AWGN Additive White Gaussian Noise BB Baseband BCH Bose-Chaudhuri-Hocquenghem multiple error co
29、rrection binary block code CCM Constant Coding and Modulation CNR Carrier-to-Noise Ratio CRC Cyclic Redundancy Check dB decibel DEMUX De-Multiplexer DS Data Slice DVB Digital Video Broadcasting DVB-C DVB system for cable transmission DVB-C2 DVB system for second generation cable transmission FEC For
30、ward Error Correction FFT Fast Fourier Transform GI Guard Interval GSE Generic Stream Encapsulation HFC Hybrid Fibre Coax IFFT Inverse Fast Fourier Transform IP Internet Protocol LDPC Low Density Parity Check (codes) MATV Master Antenna Television Mbit 220 = 1,048,576 bits Mbit/s Mbit per second MHz
31、 106 Hertz MPEG Moving Pictures Experts Group OFDM Orthogonal Frequency Division Multiplex PAPR Peak to Average Power Ratio PHY Physical Layer PLP Physical Layer Pipe QAM Quadrature Amplitude Modulation QoS Quality of Service RFoG Radio Frequency over Glass SMATV Satellite Master Antenna Television
32、Rec. ITU-T J.382 (03/2018) 3 SNR Signal-to-Noise Ratio TDM Time Division Multiplex TI Time Interleaver TS Transport Stream VCM Variable Coding and Modulation 5 Conventions None. 6 Advanced digital downstream transmission systems for cable distribution 6.1 System concept A downstream framer, capable
33、of receiving multiple formats of streams, such as MPEG-2 transport streams and Ethernet packet streams, has the function of framing these streams for efficient transmission. A downstream forward error correction (FEC) encoder, followed by a downstream framer, adds an encoding function to protect inf
34、ormation data from channel noise through HFC based networks. The downstream modulator covers functions for mapping the high order quadrature amplitude modulation (QAM) constellation in order to improve spectral efficiency, as well as interleaving mechanisms for the protection of information data fro
35、m burst noise in the time and frequency domain. The basic block diagram of advanced digital transmission processing is shown in Figure 1. Input stream does not only represent a single stream, but instead can consist of multiple independent data streams, containing signals and components of advanced
36、digital downstream transmission systems for television, sound and data services for cable distribution. The channel model of HFC-based networks is primarily a bandwidth-limited linear channel, with a balanced combination of white noise, interference and multi-path distortion. The orthogonal frequenc
37、y division multiplex (OFDM) technique with channel coding can have advantages to minimize the loss due to typical channel distortions in HFC-based networks. The advanced digital downstream transmission system shall be fully transparent with respect to the different transmitter inputs and related rec
38、eiver output signals. Upstream advanced digital transmission technologies are not covered by this Recommendation. 4 Rec. ITU-T J.382 (03/2018) J . 3 8 2 ( 1 4 ) _ F 0 1I npu t s t r e a mM P E G - T S orot he r s t r e a m s( L D P C / B C H )D ow ns t r e a mF E C e nc ode rD ow ns t r e a mde f r
39、a m e rD ow ns t r e a mf r a m e rD ow ns t r e a mm odu l a t or( O F D M )D ow ns t r e a mde m odu l a t orD ow ns t r e a mF E C de c ode rO ut put s t r e a mR e c e i ve rT r an s m i t t e rH F C b as e d n e t w or k sFigure 1 System concept for advanced digital downstream transmission syst
40、em 6.2 Specifications of advanced digital downstream transmission systems Advanced digital downstream transmission systems are required to support the following technical specifications regarding framing, channel coding and modulation. The fundamental framework is described in Table 1 and extended p
41、arameters are defined in Table 2. Table 1 PHY downstream specifications in summary form indicating fundamental framework Item Specification Input signals MPEG-TS, any packetized or continuous stream Framing structure Two dimensional time division multiplex (TDM) structure: physical layer pipes (PLPs
42、) and data slice (DS) Signalling method Embedded in the TDM framing structure Modulation scheme OFDM FFT size 4096 for 8 MHz channel (2.232 kHz carrier spacing) or 4096 for 6 MHz channel (1.674 kHz carrier spacing) Number of payload carriers 3408 for a 8 MHz channel Channel coding Randomization FEC
43、frame scrambling (1 + X14 + X15) FEC LDPC/BCH Interleaving Bit-, time and frequency interleaving Modulation Bandwidth 6 or 8 MHz basis, flexibility for wider bandwidth (up to 450 MHz) Constellation 16/64/256/1024/4096 QAM Pilots Scattered, continual and edge-pilots Guard interval (GI) 1/64 or 1/128
44、Rec. ITU-T J.382 (03/2018) 5 Table 2 Extended parameters Item Specification Channel coding Bit-Interleaving Parity- and column twist Interleaving Time-Interleaving At data slice (DS) level: Block interleaving with 0, 4, 8,16 symbols interleaving depth Frequency-Interleaving At DS level Service-relat
45、ed robustness Robustness parameters (modulation scheme and FEC parameters) can be chosen per PLP Variable coding and modulation (VCM) Modulation parameters may be changed each DVB-C2 Frame Adaptive coding and modulation (ACM) Possible Two layer multiplexing structure Physical layer pipe (PLP): indiv
46、idual modulation parameters data slice (DS): Group of PLPs with individual time-/frequency interleaving settings Modulation Byte to symbol mapping Depending on modulation scheme and FEC code rate Roll-off factor Not defined Baseband filter characteristics Not defined Pilots Pilot density depending o
47、n guard interval (GI) choice Peak-to-average-power-ratio (PAPR) Reduction of PAPR is possible by reserved tones Hooks for extensions Available The frequency allocation is not specified in this Recommendation, however the system is recommended to allow flexibility in order to reflect each countrys us
48、age of the frequency space. The text of ETSI EN 302 769 is applied with the modifications as given below: Un-numbered clauses “Intellectual Property Rights“ and “Foreword“ The introductory clauses labelled “Intellectual Property Rights“ and “Foreword“ do not apply in the context of this Recommendati
49、on. 6 Rec. ITU-T J.382 (03/2018) Appendix I A digital video broadcasting (DVB); Frame structure channel coding and modulation for a second generation digital transmission system for cable systems (DVB-C2) (This appendix does not form an integral part of this Recommendation.) I.1 Introduction This appendix derives from work done by the Digital Video Broadcasting (DVB) Project. The specification of the second generation DVB cable transmission system (i.e., DVB-C2) has been adopted by the Joint Technical Committee (JTC) of the European Broadcasting
