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 G.9701 TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU Amendment 4 (12/2017) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS Access networks Metallic access networks Fast access to subscriber terminal
2、s (G.fast) Physical layer specification Amendment 4 Recommendation ITU-T G.9701 (2014) Amendment 4 ITU-T G-SERIES RECOMMENDATIONS TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS G.100G.199 GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CA
3、RRIER-TRANSMISSION SYSTEMS G.200G.299 INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES G.300G.399 GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES G.400G.449 COORDINATIO
4、N OF RADIOTELEPHONY AND LINE TELEPHONY G.450G.499 TRANSMISSION MEDIA AND OPTICAL SYSTEMS CHARACTERISTICS G.600G.699 DIGITAL TERMINAL EQUIPMENTS G.700G.799 DIGITAL NETWORKS G.800G.899 DIGITAL SECTIONS AND DIGITAL LINE SYSTEM G.900G.999 MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE GENERIC AND USER-RE
5、LATED ASPECTS G.1000G.1999 TRANSMISSION MEDIA CHARACTERISTICS G.6000G.6999 DATA OVER TRANSPORT GENERIC ASPECTS G.7000G.7999 PACKET OVER TRANSPORT ASPECTS G.8000G.8999 ACCESS NETWORKS G.9000G.9999 Metallic access networks G.9700G.9799 Optical line systems for local and access networks G.9800G.9899 In
6、 premises networks G.9900G.9999 For further details, please refer to the list of ITU-T Recommendations. Rec. ITU-T G.9701 (2014)/Amd.4 (12/2017) i Recommendation ITU-T G.9701 Fast access to subscriber terminals (G.fast) Physical layer specification Amendment 4 Summary Recommendation ITU-T G.9701 spe
7、cifies a gigabit broadband access technology that exploits the existing infrastructure of wire-pairs that were originally deployed for plain old telephone service (POTS) services. Equipment implementing this Recommendation can be deployed from fibre-fed distribution points (fibre to the distribution
8、 point, FTTdp) located very near the customer premises, or within buildings (fibre to the building, FTTB). This Recommendation supports asymmetric and symmetric transmission at an aggregate net data rate up to 1 Gbit/s on twisted wire-pairs using spectrum up to 106 MHz and specifies all necessary fu
9、nctionality to support far-end crosstalk (FEXT) cancellation between multiple wire-pairs, and facilitates low power operation. Corrigendum 1 (2015) provides clarifications and corrects various errors in the Recommendation, and in particular includes a change to the definition of DFT output samples.
10、Corrigendum 2 (2016) increases the number of RFI bands from 16 to 32, and provides clarifying text on alignment between TIGA and SRA/FRA procedures, tone repetition, unavailable seconds, and byte order in SOC and eoc messages. Amendment 1 (2016) specifies test parameters, some of which had previousl
11、y been left for further study, and specifies support for low power operation. Amendment 2 (2016) includes a new annex on cross-layer traffic monitoring functions and link state control to support low power operation. It also includes a new 106 MHz profile with increased maximum transmit power, suppo
12、rt for increased bit loading, Hlog reporting in both directions, and Xlog reporting. Corrigendum 3 (2017) adds several clarifications, and fixes various errors and inconsistencies. Amendment 3 adds support for new functionality: full specification of the 212 MHz profile, Annex X Operation without mu
13、lti-line coordination intended for a crosstalk free environment (e.g., coaxial cable medium) including dynamic time assignment (DTA), Annex T higher layer control aspects of DTA, and Annex S software download to NTs. Amendment 4 supports new functionality for impulse noise monitoring (INM), robust m
14、anagement channel recovery (RMCR), and performance monitoring parameter ANDEFTR. History Edition Recommendation Approval Study Group Unique ID* 1.0 ITU-T G.9701 2014-12-05 15 11.1002/1000/12090 1.1 ITU-T G.9701 (2014) Cor. 1 2015-11-22 15 11.1002/1000/12541 1.2 ITU-T G.9701 (2014) Cor. 2 2016-05-07
15、15 11.1002/1000/12817 1.3 ITU-T G.9701 (2014) Amd. 1 2016-05-07 15 11.1002/1000/12542 1.4 ITU-T G.9701 (2014) Amd. 2 2016-07-22 15 11.1002/1000/12816 1.5 ITU-T G.9701 (2014) Cor. 3 2017-04-06 15 11.1002/1000/13069 1.6 ITU-T G.9701 (2014) Amd. 3 2017-04-06 15 11.1002/1000/13068 1.7 ITU-T G.9701 (2014
16、) Cor. 4 2017-12-07 15 11.1002/1000/13332 1.8 ITU-T G.9701 (2014) Amd. 4 2017-12-07 15 11.1002/1000/13331 _ * 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/11.100
17、2/1000/11830-en. ii Rec. ITU-T G.9701 (2014)/Amd.4 (12/2017) 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-
18、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 (WTSA), which meets every four ye
19、ars, 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 nec
20、essary 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 Recommendation is voluntary. Howev
21、er, 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 language such as “must“ and the negative
22、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 Recommendation may involve the use of
23、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 Recommendation, ITU
24、 had 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 TSB patent database at http:/www.itu.int
25、/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 G.9701 (2014)/Amd.4 (12/2017) iii Table of Contents Page 1 Scope . 1 2 References . 3 3 Definitions 3 3.1 Terms defined elsewhere
26、 3 3.2 Terms defined in this Recommendation . 3 4 Abbreviations and acronyms 7 5 Reference models and system requirements . 11 5.1 System reference models 11 5.2 Application reference models . 15 5.3 FTU protocol reference model . 20 5.4 FTU functional model 22 5.5 INP system requirements 24 6 Profi
27、les 24 6.1 Definition 24 6.2 Profile compliance 26 7 Transmission medium interface characteristics 27 7.1 Duplexing method 27 7.2 Frequency band 27 7.3 Power spectral density 27 7.4 Out-of-band PSD limit . 41 7.5 Termination impedance 41 7.6 Maximum aggregate transmit power 41 8 Transport protocol s
28、pecific transmission convergence (TPS-TC) function . 41 8.1 Functional reference model 41 8.2 Generic DTU format . 50 8.3 Packet-based TPS-TC (PTM-TC) 52 8.4 Network timing reference (NTR) . 55 8.5 Time-of-day (ToD) . 57 9 Physical media specific transmission convergence (PMS-TC) sub-layer 61 9.1 Fu
29、nctional reference model 61 9.2 DTU scrambler . 64 9.3 DTU encoder 64 9.4 Interleaver . 65 9.5 Data frame multiplexer . 66 9.6 RMC . 69 9.7 Acknowledgement 80 iv Rec. ITU-T G.9701 (2014)/Amd.4 (12/2017) Page 9.8 Retransmission function . 83 10 Physical media dependent (PMD) function 91 10.1 PMD func
30、tional reference model . 91 10.2 Symbol encoder 95 10.3 Precoder (downstream vectoring) . 117 10.4 Modulation . 132 10.5 TDD frame structure . 135 10.6 Superframe structure 138 10.7 Normal and discontinuous operation intervals . 139 10.8 Alignment of transmissions in vectored group . 144 11 Operatio
31、n and maintenance (OAM) . 144 11.1 OAM functional model . 144 11.2 Management functions and procedures over eoc . 148 11.3 OAM primitives 198 11.4 OAM parameters 202 12 Link activation methods and procedures 235 12.1 Overview 235 12.2 Special operations channel (SOC) 253 12.3 Initialization procedur
32、e . 257 12.4 Loop diagnostics mode . 327 13 Online reconfiguration (OLR) 328 13.1 Overview 328 13.2 Eoc-based procedures . 329 13.3 RMC-based procedures 344 13.4 Low power link states . 351 14 Electrical requirements . 369 14.1 Balance . 369 14.2 Differential port impedance 370 Annex A to Annex R 37
33、1 Annex S NT software upgrade 372 S.1 Scope 372 S.2 References 372 S.3 Reference model . 372 S.4 Software image management process 373 S.5 Message set . 378 S.6 Software upgrade (informative) . 389 Annex T Dynamic time assignment (DTA) higher-layer control aspects . 395 T.1 Scope 395 T.2 DTA control
34、 parameters . 395 Rec. ITU-T G.9701 (2014)/Amd.4 (12/2017) v Page T.3 Coordination between the link state request and the DTA request 397 Annex U to Annex W. 398 Annex X Operation without multi-line coordination intended for a crosstalk-free environment 399 X.1 Scope 399 X.2 Definitions 399 X.3 Abbr
35、eviations and acronyms 399 X.4 Reference model(s) . 399 X.5 Profiles 400 X.6 Dynamic time assignment (DTA) 402 X.7 Initialization messages 409 X.8 Discontinuous operation . 412 X.9 On-line reconfiguration 412 X.10 Initialization 413 X.11 Low power states 413 X.12 Adaptation to the coaxial cable medi
36、um 413 Annex Y Upstream dynamic resource reports 418 Annex Z Cross-layer traffic monitoring functions and link state control . 420 Z.0 Introduction 420 Z.1 Definition of Terms 420 Z.2 Abbreviations and acronyms 420 Z.3 Reference models . 421 Z.4 Generic traffic monitoring functions 422 Z.5 Generic i
37、nformation flows 424 Z.6 Link state specific functions . 427 Z.7 Link state management and reporting parameters 431 Appendix I Wiring topologies and reference loops 433 I.1 Wiring topologies . 433 I.2 Reference loops 433 Appendix II Example OLR use cases . 442 II.1 Transmitter initiated gain adjustm
38、ent (TIGA) 442 Appendix III Motivation of MTBE accelerated test . 444 Appendix IV . 446 Appendix V Retransmission buffer size and the achievable bit-rate 447 V.1 Case 1: NSYMret+NSYMack+1 Mus 447 V.2 Case 2: NSYMret+NSYMack+1Mus. 448 V.3 Case 3: Lower bound for the achievable net data rate 448 V.4 M
39、emory size example . 449 Appendix VI Example applications of discontinuous operation 450 vi Rec. ITU-T G.9701 (2014)/Amd.4 (12/2017) Page VI.1 Discontinuous operation with vectoring disabled 450 VI.2 Examples of discontinuous operation with vectoring enabled . 451 Appendix VII Calculation of loop at
40、tenuation (LATN) . 457 Appendix VIII Impulse noise monitoring detection and interpretation of impulse noise using clusters of corrupted DTUs 458 VIII.1 Overview 458 VIII.2 Expected accuracy of impulse noise events . 460 Bibliography. 462 Rec. ITU-T G.9701 (2014)/Amd.4 (12/2017) 1 Recommendation ITU-
41、T G.9701 Fast access to subscriber terminals (G.fast) Physical layer specification Amendment 4 Editorial note: This is a complete-text publication. Except for new Appendix VIII, changes introduced by this amendment are shown in revision marks relative to Recommendation ITU-T G.9701 (2014) plus Errat
42、um 1, Corrigenda 1, 2 and 3, Amendments 1, 2 and 3. 1 Scope This Recommendation specifies the operation of a broadband access technology that exploits the existing infrastructure of wire-pairs that were originally deployed for plain old telephone service (POTS) and, with Amendment 3, adds support fo
43、r operation over coaxial cables. This Recommendation supports transmission at an aggregate net data rate (the sum of upstream and downstream rates) up to approximately 2 Gbit/s. Whilst asymmetric digital subscriber line transceivers 2 (ADSL2) extended bandwidth (ADSL2plus) uses approximately 2 MHz o
44、f the spectrum, and very high speed digital subscriber line transceivers 2 (VDSL2) uses up to 35 MHz of the spectrum, this Recommendation defines profiles using spectrum up to 106 MHz and 212 MHz and specifies all necessary functionality to support the use of far-end crosstalk (FEXT) cancellation be
45、tween ITU-T G.9701 transceivers deployed on multiple wire-pairs. The availability of spectrum up to 106 MHz or 212 MHz allows ITU-T G.9701 transceivers to provide reliable high data rate operation on very short loops. This Recommendation can be deployed from fibre-fed distribution points located ver
46、y near the customer premises, or within the buildings. This Recommendation is optimized to operate over wire-pairs up to approximately 250 m of 0.5 mm diameter. However, it is capable of operation over wire-pairs up to at least 400 meters of 0.5 mm diameter, subject to some performance limitations.
47、This Recommendation defines a wide range of settings for various parameters (such as spectral usage and transmitter power) that may be supported by a transceiver. Therefore, this Recommendation specifies profiles to allow transceivers to support a subset of the allowed settings and still be complian
48、t with the Recommendation. The specification of multiple profiles allows vendors to limit the implementation complexity and develop implementations that target specific service requirements. This edition of the Recommendation specifies transmission profiles for in-band spectral usage of up to 212 MH
49、z and maximum transmit power up to +8 dBm. This Recommendation operates in compliance with the power spectral density (PSD) specification in ITU-T G.9700. As do ITU-T Recommendations in the ITU-T G.99x series, this Recommendation uses ITU-T G.994.1 to initiate the transceiver training sequence. Through negotiation during the handshake phase of the initialization, the capability of equipmen
