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 Corrigendum 2 (05/2016) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS Access networks Metallic access networks Fast access to subscriber termin
2、als (G.fast) Physical layer specification Corrigendum 2 Recommendation ITU-T G.9701 (2014) Corrigendum 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 ANALO
3、GUE CARRIER-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 COORD
4、INATION 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 U
5、SER-RELATED 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.9
6、899 In premises networks G.9900G.9999 For further details, please refer to the list of ITU-T Recommendations. Rec. ITU-T G.9701 (2014)/Cor.2 (05/2016) i Recommendation ITU-T G.9701 Fast access to subscriber terminals (G.fast) Physical layer specification Corrigendum 2 Summary Recommendation ITU-T G.
7、9701 specifies 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 dist
8、ribution 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 nece
9、ssary functionality to support far-end crosstalk (FEXT) cancellation between multiple wire-pairs, and facilitates low power operation. Corrigendum 1 (2014) provides clarifications and corrects various errors in the Recommendation, and in particular includes a change to the definition of DFT output s
10、amples. This Corrigendum 2 to Recommendation ITU-T G.9701 (2014) 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. History Edition Recommendatio
11、n 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 1.3 ITU-T G.9701 (2014) Cor. 2 2016-05-07 15 11.1002/1000/12817 1.4 ITU-T G.9701 (2014) Amd. 1 2016-05-07 15 11.1002/1000/12542 _ * To access the Recomm
12、endation, 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 G.9701 (2014)/Cor. 2 (05/2016) FOREWORD The International Telecommunication Union (ITU) is the Unit
13、ed 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 responsible for studying technical, operating and tariff questions and issuing Recommend
14、ations 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 study groups which, in turn, produce Recommendations on these topics. The appr
15、oval 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 basis with ISO and IEC. NOTE In this Recommendation, the expression “Administrat
16、ion“ 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 mandatory provisions (to ensure, e.g., interoperability or applicability) and complian
17、ce 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 use of such words does not suggest that compliance with the Recommendation is r
18、equired of any party. INTELLECTUAL PROPERTY RIGHTSITU 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 no position concerning the evidence, validity or applicability of claimed Intell
19、ectual 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 received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. Howe
20、ver, 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 2016 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the pr
21、ior written permission of ITU. Rec. ITU-T G.9701 (2014)/Cor.2 (05/2016) iii Table of Contents Page 1 Scope . 1 2 References . 3 3 Definitions 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.
22、1 System reference models 11 5.2 Application reference models . 14 5.3 FTU protocol reference model . 19 5.4 FTU functional model 21 5.5 INP system requirements 23 6 Profiles 23 6.1 Definition 23 6.2 Profile compliance 24 7 Transmission medium interface characteristics 25 7.1 Duplexing method 25 7.2
23、 Frequency band 25 7.3 Power spectral density 26 7.4 Out-of-band PSD limit . 39 7.5 Termination impedance 39 7.6 Maximum aggregate transmit power 39 8 Transport protocol specific transmission convergence (TPS-TC) function . 40 8.1 Functional reference model 40 8.2 Generic DTU format . 48 8.3 Packet-
24、based TPS-TC (PTM-TC) 50 8.4 Network timing reference (NTR) . 53 8.5 Time-of-day (ToD) . 54 9 Physical media specific transmission convergence (PMS-TC) sub-layer 59 9.1 Functional reference model 59 9.2 DTU scrambler . 62 9.3 DTU encoder 62 9.4 Interleaver . 63 9.5 Data frame multiplexer . 64 9.6 RM
25、C . 67 9.7 Acknowledgement 77 9.8 Retransmission function . 79 iv Rec. ITU-T G.9701 (2014)/Cor. 2 (05/2016) Page 10 Physical media dependent (PMD) function 87 10.1 PMD functional reference model . 87 10.2 Symbol encoder 91 10.3 Precoder (downstream vectoring) . 113 10.4 Modulation . 128 10.5 TDD fra
26、me structure . 131 10.6 Superframe structure 134 10.7 Normal and discontinuous operation intervals . 135 10.8 Alignment of transmissions in vectored group . 140 11 Operation and maintenance (OAM) . 140 11.1 OAM functional model . 140 11.2 Management functions and procedures over eoc . 143 11.3 OAM p
27、rimitives 180 11.4 OAM parameters 183 12 Link activation methods and procedures 191 12.1 Overview 191 12.2 Special operations channel (SOC) 206 12.3 Initialization procedure . 210 12.4 Loop diagnostics mode . 273 13 Online reconfiguration (OLR) 273 13.1 Overview 273 13.2 Eoc-based procedures . 274 1
28、3.3 RMC-based procedures 287 13.4 Low power states 292 14 Electrical requirements . 292 14.1 Balance . 292 14.2 Differential port impedance 293 Appendix I Wiring topologies and reference loops 294 I.1 Wiring topologies . 294 I.2 Reference loops 294 Appendix II Example OLR use cases . 303 II.1 Transm
29、itter initiated gain adjustment (TIGA) 303 Appendix III Motivation of MTBE accelerated test . 305 Appendix IV Upstream dynamic resource reports 307 Appendix V Retransmission buffer size and the achievable bit-rate 309 V.1 Case 1: NSYMret+NSYMack+1 Mus 309 V.2 Case 2: NSYMret+NSYMack+1Mus. 310 V.3 Ca
30、se 3: Lower bound for the achievable net data rate 310 V.4 Memory size example . 311 Rec. ITU-T G.9701 (2014)/Cor.2 (05/2016) v Page Appendix VI Example applications of discontinuous operation 312 VI.1 Discontinuous operation with vectoring disabled 312 VI.2 Examples of discontinuous operation with
31、vectoring enabled . 313 Bibliography. 319 Rec. ITU-T G.9701 (2014)/Cor.2 (05/2016) 1 Recommendation ITU-T G.9701 Fast access to subscriber terminals (G.fast) Physical layer specification Editorial note: This is a complete-text publication. Modifications introduced by this corrigendum are shown in re
32、vision marks relative to Recommendation ITU-T G.9701 (2014) plus Erratum 1 and Corrigendum 1. 1 Scope This Recommendation supports transmission at an aggregate net data rate (the sum of upstream and downstream rates) up to approximately 1 Gbit/s on twisted wire-pairs. This Recommendation specifies t
33、he 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 line transceivers 2 (ADSL2) extended bandwidth (ADSL2plus) uses approximately 2 MHz of the
34、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 necessary functionality to support the use of far-end crosstalk (FEXT) cancellation between
35、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 very near
36、 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. This R
37、ecommendation 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 compliant with
38、 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 the profile for in-band spectral usage of up to 106 MHz at 4dBm maximu
39、m 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. As do ITU-T Recommendations in the ITU-T G.99x series, this Recommendation uses ITU-T G.99
40、4.1 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 Recommendations (e.g., b-ITU-T G.993.2 defining VDSL2) is identified. For reasons of interoper
41、ability, 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 negotiation during the initialization, U interface compatibility and interoperability between tran
42、sceivers complying with this Recommendation, including transceivers that support different combinations of options. The technology specified in this Recommendation provides the following key application features: Best aspects of fibre to the home (FTTH): up to one gigabit per second aggregate net da
43、ta rate; Best aspects of ADSL2: customer self-install and operation in the presence of bridged taps, avoiding operator truck-rolls to the customer premises for installation and activation of the broadband access service; 2 Rec. ITU-T G.9701 (2014)/Cor. 2 (05/2016) Coexistence with ADSL2 and VDSL2 on
44、 adjacent wire-pairs; Low power modes 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 environmental conditions (e.g., temperature); Management capabilities allowing transceivers to opera
45、te 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 time to adapt net data rates to the needs of the business and the residential customers; Vector
46、ing (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; Netwo
47、rk timing reference (NTR) and time-of-day (ToD) transport for network frequency and time synchronization between network and customer premises equipment; Configuration of spectrum use, including configuration of the transmit power spectral density (PSD) limitations and notches to meet electromagneti
48、c compatibility (EMC) requirements. The technology specified in this Recommendation uses the following key functionalities and capabilities: Transparent transport of data packets (e.g., Ethernet packets) at an aggregate (sum of upstream and downstream) data rate of up to 1 Gbit/s; In-band spectral u
49、sage up to 212 MHz, with this edition of the Recommendation specifying one profile up to 106 MHz at 4dBm transmit power; Configurable start and stop frequencies, PSD shaping and notching; Discrete multitone (DMT) modulation (2 048/4 096 subcarriers with 51.75 kHz subcarrier spacing); Time-division duplexing (sharing time between upstream and downstream transmission); Low latency retransmission, facilitating impulse noise protection (INP) be
