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 2 (07/2016) 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 2 Recommendation ITU-T G.9701 (2014) Amendment 2 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.2 (07/2016) i Recommendation ITU-T G.9701 Fast access to subscriber terminals (G.fast) Physical layer specification Amendment 2 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 specified test parameters, some of which had previously been
11、left for further study, and specifies support for low power operation. This amendment 2 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, support for in
12、creased bit loading, Hlog reporting in both directions, and Xlog reporting. 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 11
13、.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 _ * 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. F
14、or example, http:/handle.itu.int/11.1002/1000/11830-en. ii Rec. ITU-T G.9701 (2014)/Amd.2 (07/2016) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecom
15、munication 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 Ass
16、embly (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 wh
17、ich fall 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
18、this 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 la
19、nguage 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
20、 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 the Recommendation development process. As of the date
21、of approval of this Recommendation, ITU 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 T
22、SB patent database at http:/www.itu.int/ITU-T/ipr/. ITU 2016 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.2 (07/2016) iii Table of Contents Page 1 Scope . 1 2 References . 3 3 De
23、finitions 3 3.1 Terms defined elsewhere 3 3.2 Terms defined in this Recommendation . 3 4 Abbreviations and acronyms 6 5 Reference models and system requirements . 11 5.1 System reference models 11 5.2 Application reference models . 14 5.3 FTU protocol reference model . 19 5.4 FTU functional model 21
24、 5.5 INP system requirements 23 6 Profiles 23 6.1 Definition 23 6.2 Profile compliance 25 7 Transmission medium interface characteristics 26 7.1 Duplexing method 26 7.2 Frequency band 26 7.3 Power spectral density 26 7.4 Out-of-band PSD limit . 40 7.5 Termination impedance 40 7.6 Maximum aggregate t
25、ransmit power 40 8 Transport protocol specific transmission convergence (TPS-TC) function . 40 8.1 Functional reference model 40 8.2 Generic DTU format . 49 8.3 Packet-based TPS-TC (PTM-TC) 51 8.4 Network timing reference (NTR) . 54 8.5 Time-of-day (ToD) . 56 9 Physical media specific transmission c
26、onvergence (PMS-TC) sub-layer 60 9.1 Functional reference model 60 9.2 DTU scrambler . 63 9.3 DTU encoder 63 9.4 Interleaver . 64 9.5 Data frame multiplexer . 65 9.6 RMC . 68 9.7 Acknowledgement 79 9.8 Retransmission function . 81 iv Rec. ITU-T G.9701 (2014)/Amd.2 (07/2016) Page 10 Physical media de
27、pendent (PMD) function 89 10.1 PMD functional reference model . 89 10.2 Symbol encoder 93 10.3 Precoder (downstream vectoring) . 115 10.4 Modulation . 129 10.5 TDD frame structure . 132 10.6 Superframe structure 135 10.7 Normal and discontinuous operation intervals . 136 10.8 Alignment of transmissi
28、ons in vectored group . 141 11 Operation and maintenance (OAM) . 141 11.1 OAM functional model . 141 11.2 Management functions and procedures over eoc . 144 11.3 OAM primitives 188 11.4 OAM parameters 191 12 Link activation methods and procedures 217 12.1 Overview 217 12.2 Special operations channel
29、 (SOC) 234 12.3 Initialization procedure . 238 12.4 Loop diagnostics mode . 305 13 Online reconfiguration (OLR) 306 13.1 Overview 306 13.2 Eoc-based procedures . 307 13.3 RMC-based procedures 321 13.4 Low power link states . 326 14 Electrical requirements . 344 14.1 Balance . 344 14.2 Differential p
30、ort impedance 345 Annex A to Annex X . 346 Annex Y Upstream dynamic resource reports 347 Annex Z Cross-layer traffic monitoring functions and link state control . 349 Z.0 Introduction 349 Z.1 Definition of Terms 349 Z.2 Abbreviations and acronyms 349 Z.3 Reference models . 350 Z.4 Generic traffic mo
31、nitoring functions 351 Z.5 Generic information flows 353 Z.6 Link state specific functions . 356 Z.7 Link state management and reporting parameters 360 Appendix I Wiring topologies and reference loops 362 Rec. ITU-T G.9701 (2014)/Amd.2 (07/2016) v Page I.1 Wiring topologies . 362 I.2 Reference loops
32、 362 Appendix II Example OLR use cases . 371 II.1 Transmitter initiated gain adjustment (TIGA) 371 Appendix III Motivation of MTBE accelerated test . 373 Appendix IV . 375 Appendix V Retransmission buffer size and the achievable bit-rate 376 V.1 Case 1: NSYMret+NSYMack+1 Mus 376 V.2 Case 2: NSYMret+
33、NSYMack+1Mus. 377 V.3 Case 3: Lower bound for the achievable net data rate 377 V.4 Memory size example . 378 Appendix VI Example applications of discontinuous operation 379 VI.1 Discontinuous operation with vectoring disabled 379 VI.2 Examples of discontinuous operation with vectoring enabled . 380
34、Appendices VII to YX . 386 Appendix YY Calculation of loop attenuation (LATN) . 387 Bibliography. 388 Rec. ITU-T G.9701 (2014)/Amd.2 (07/2016) 1 Recommendation ITU-T G.9701 Fast access to subscriber terminals (G.fast) Physical layer specification Amendment 2 Editorial note: This is a complete-text p
35、ublication. Modifications introduced by this amendment are shown in revision marks relative to Recommendation ITU-T G.9701 (2014) plus Erratum 1, Corrigenda 1 and 2, and Amendment 1. 1 Scope This Recommendation supports transmission at an aggregate net data rate (the sum of upstream and downstream r
36、ates) up to approximately 1 Gbit/s on twisted wire-pairs. 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). Whilst asymmetric digital subscriber li
37、ne transceivers 2 (ADSL2) extended bandwidth (ADSL2plus) uses approximately 2 MHz of the spectrum, and very high speed digital subscriber line transceivers 2 (VDSL2) uses up to 30 MHz of the spectrum, this Recommendation defines profiles using spectrum up to 106 MHz and 212 MHz and specifies all nec
38、essary functionality to support the use of far-end crosstalk (FEXT) cancellation between 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.
39、 This Recommendation can be deployed from fibre-fed distribution points located very 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 t
40、o at least 400 meters of 0.5 mm diameter, subject to some performance limitations. 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 a
41、llow transceivers to support a subset of the allowed settings and still be compliant 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 Recomm
42、endation specifies the profile for in-band spectral usage of up to 106 MHz at 4dBm maximum transmit power. A second profile for in-band spectral usage up to 212 MHz is for further study. This Recommendation operates in compliance with the power spectral density (PSD) specification in ITU-T G.9700. A
43、s 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 equipment to support this Recommendation and/or ITU-T G.99x series Recom
44、mendations (e.g., b-ITU-T G.993.2 defining VDSL2) is identified. For reasons of interoperability, equipment may support multiple Recommendations such that it is able to adapt to the operating mode supported by the far-end equipment. It is the intention of this Recommendation to provide, by negotiati
45、on during the initialization, U interface compatibility and interoperability between transceivers complying with this Recommendation, including transceivers that support different combinations of options. The technology specified in this Recommendation provides the following key application features
46、: Best aspects of fibre to the home (FTTH): up to one gigabit per second aggregate net data rate; 2 Rec. ITU-T G.9701 (2014)/Amd.2 (07/2016) Best aspects of ADSL2: customer self-install and operation in the presence of bridged taps, avoiding operator truck-rolls to the customer premises for installa
47、tion and activation of the broadband access service; Coexistence with ADSL2 and VDSL2 on adjacent wire-pairs; Low power operation and all functionality necessary to allow transceivers to be deployed as part of reverse powered (and possibly battery operated) network equipment and to adapt to environm
48、ental conditions (e.g., temperature); Management capabilities allowing transceivers to operate in a zero touch deployment, avoiding truck-rolls to the network equipment for installation and activation of new or upgraded broadband access service; Control of the upstream vs downstream transmission tim
49、e to adapt net data rates to the needs of the business and the residential customers; Vectoring (self-crosstalk cancellation) for increased net data rates on wire-pairs that experience far-end crosstalk from ITU-T G.9701 transceivers in the same vectored group operating on other wire-pairs in the same cable or operating on other wire-pairs originating from the same network equipment; Network timing reference (NTR) and time-of-day (ToD) transport
