1、 International Telecommunication Union ITU-T J.382TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (01/2014) SERIES J: CABLE NETWORKS AND TRANSMISSION OF TELEVISION, SOUND PROGRAMME AND OTHER MULTIMEDIA SIGNALS Digital transmission of television signals Advanced digital downstream transmission system
2、s for television, sound and data services for cable distribution Recommendation ITU-T J.382 Rec. ITU-T J.382 (01/2014) i Recommendation ITU-T J.382 Advanced digital downstream transmission systems for television, sound and data services for cable distribution Summary Recommendation ITU-T J.382 provi
3、des 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 covers the common definition of framing
4、 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 2014-01-13 9 11.1002/1000/12104-en Keywords
5、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 unique ID. For example, http:/handle.itu.int/11.1002/1000/11830-en. ii Rec. ITU-T J.382
6、(01/2014) FOREWORD The International Telecommunication Union (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 responsibl
7、e 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 years, establishes the topics for study by the ITU-T
8、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 necessary standards are prepared on a collaborative ba
9、sis 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 Recommendation is voluntary. However, the Recommendation may contain certain mandator
10、y 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 language such as “must“ and the negative equivalents are used to express requirements. The u
11、se of such words does not suggest 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 n
12、o 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 Recommendation, ITU had not received notice of intellectual property,
13、 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 TSB patent database at http:/www.itu.int/ITU-T/ipr/. ITU 2014 All rights reserved. No
14、part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. Rec. ITU-T J.382 (01/2014) 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
15、 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 Appendix I A digital video broadcasting (DVB); Frame structure channel coding and modulation f
16、or 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 concept . 10 Bibliography. 12 iv Rec. ITU-T J.382 (01/2014) Introduction As the demand of hi
17、gh quality broadcast and multicast services from consumers side is increasing, cable operators seriously search for more efficient ways to transmit those services through hybrid fibre coax (HFC) based networks. Modulation and coding schemes for global use in cable industry are based on b-ITU-T J.83,
18、 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 256 QAM modulation scheme and thus do not serve demands for advanced digital downstream transmission systems. In the near future, advanced digital t
19、ransmission systems including enhanced coding and modulation, can replace digital cable transmission systems defined in b-ITU-T J.83. Rec. ITU-T J.382 (01/2014) 1 Recommendation ITU-T J.382 Advanced digital downstream transmission systems for television, sound and data services for cable distributio
20、n 1 Scope The scope of this Recommendation is to define a globally common specification for framing structure, channel coding and modulation schemes for television, sound and data services including high quality broadcast and multicast services for downstream distributed through hybrid fibre coax (H
21、FC) based networks to provide high spectral efficiency. This Recommendation will contribute to the development of common products for cable broadcast and telecommunication downstream physical layer (PHY). The specifications included in this Recommendation are based on the requirements defined in ITU
22、-T J.381. 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
23、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-T Recommendations is regularly published. The reference to a document with
24、in 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), Requirements for advanced digital transmission technologies. ETSI EN 302 769 ETSI EN 302 769 V1.2.1 (2011), Digital Video Broadcasting (DVB); Frame struc
25、ture channel coding and modulation for a second generation digital transmission system for cable systems (DVB-C2). 3 Definitions 3.1 Terms defined elsewhere This Recommendation uses the following term defined elsewhere: 3.1.1 HFC-based networks ITU-T J.381: HFC-based networks include legacy cable ne
26、tworks such as hybrid fibre coax; recent technology deployments such as radio frequency over glass (RFoG) and cable network technologies that may be deployed in the near future. 3.2 Terms defined in this Recommendation None. 4 Abbreviations and acronyms This Recommendation uses the following abbrevi
27、ations and acronyms: 16-QAM 16-ary Quadrature Amplitude Modulation 64-QAM 64-ary Quadrature Amplitude Modulation 256-QAM 256-ary Quadrature Amplitude Modulation 2 Rec. ITU-T J.382 (01/2014) 1024-QAM 1024-ary Quadrature Amplitude Modulation 4096-QAM 4096-ary Quadrature Amplitude Modulation ACM Adapti
28、ve Coding and Modulation ADC Analogue-to-Digital Converter AWGN Additive White Gaussian Noise BB Baseband BCH Bose-Chaudhuri-Hocquenghem multiple error correction binary block code CCM Constant Coding and Modulation CENELEC Comit Europeen de Normalisation lectrotechnique CNR Carrier-to-Noise Ratio C
29、RC Cyclic Redundancy Check dB decibel DEMUX De-Multiplexer DS Data Slice DVB Digital Video Broadcasting project DVB-C DVB system for cable transmission DVB-C2 DVB system for second generation cable transmission EBU European Broadcasting Union ETSI European Telecommunications Standards Institute FEC
30、Forward 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 ISO/IEC International Organization for Standardization/International Electrotechnical Commission JTC Joint Technical C
31、ommittee LDPC Low Density Parity Check (codes) MATV Master Antenna Television Mbit 220= 1,048,576 bits Mbit/s Mbit per second MHz 106Hertz MPEG Moving Pictures Experts Group NA Not Applicable OFDM Orthogonal Frequency Division Multiplex Rec. ITU-T J.382 (01/2014) 3 PAPR Peak to Average Power Ratio P
32、HY Physical Layer PLP Physical Layer Pipe QAM Quadrature Amplitude Modulation QoS Quality of Service RF(oG) Radio Frequency (over Glass) SMATV Satellite Master Antenna Television SNR Signal-to-Noise Ratio TDM Time Division Multiplex TI Time Interleaver TS Transport Stream VCM Variable Coding and Mod
33、ulation 5 Conventions None. 6 Advanced digital downstream transmission systems for cable distribution 6.1 System concept A downstream framer, capable of receiving multiple formats of streams, such as MPEG-2 transport streams and Ethernet packet streams, has the function of framing these streams for
34、efficient transmission. A downstream forward error correction (FEC) encoder, followed by a downstream framer, adds an encoding function to protect information data from channel noise through HFC based networks. The downstream modulator covers functions of mapping high order quadrature amplitude modu
35、lation (QAM) constellation in order to improve spectral efficiency, as well as interleaving mechanisms for the protection of information data from burst noise in time and frequency domain. The basic block diagram of advanced digital transmission processing is shown in Figure 1. Input stream does not
36、 only represent a single stream, but instead can consist of multiple independent data streams, containing signals and components of advanced digital downstream transmission systems for television, sound and data services for cable distribution. The channel model of HFC-based networks is primarily a
37、bandwidth-limited linear channel, with a balanced combination of white noise, interference and multi-path distortion. Orthogonal frequency division multiplex (OFDM) technique with channel coding can have advantages to minimize the loss due to typical channel distortions in HFC-based networks. The ad
38、vanced digital downstream transmission system shall be fully transparent with respect to the different transmitter input and related receiver output signals. Upstream advanced digital transmission technologies are not covered by this Recommendation. 4 Rec. ITU-T J.382 (01/2014) J.382(14)_F01Input st
39、reamMPEG-TS orother streams(LDPC/BCH)DownstreamFEC encoderDownstreamdeframerDownstreamframerDownstreammodulator(OFDM)DownstreamdemodulatorDownstreamFEC decoderOutput streamReceiverTransmitterHFC based networksFigure 1 System concept for advanced digital downstream transmission system 6.2 Specificati
40、ons 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. Fundamental framework is described in Table 1 and extended parameters are defined
41、 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 TDM structure: physical layer pipes (PLPs) and data slice (DS) Signalling method Embedde
42、d 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 frame scrambling (1 + X14 + X15) FEC LDPC/BCH I
43、nterleaving 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 Rec. ITU-T J.382 (01/2014) 5 Table 2 Extended p
44、arameters 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-related robustness Robustness parameters (modulation
45、 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): individual modulation parameters data slice (DS): Gr
46、oup 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 on guard interval (GI) choice Peak-to-average-po
47、wer-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 usage of the frequency space. The text of ETSI EN
48、 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 Recommendation. 6 Rec. ITU-T J.382 (01/2014) Appendix I A dig
49、ital 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 Project (DVB). 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 Union (EBU), Comit Europen d
