1、 International Telecommunication Union ITU-T G.993.5 TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU Amendment 2 (12/2017) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS Digital sections and digital line system Metallic access networks Self-FEXT cancellation (vectoring) for u
2、se with VDSL2 transceivers Amendment 2 Recommendation ITU-T G.993.5 (2015) 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 CARRIER- TRANS
3、MISSION 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 COORDINATION OF RADIOT
4、ELEPHONY 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 General G.900G.909 Parameters for optical fibre cable systems G.910G.919 Dig
5、ital sections at hierarchical bit rates based on a bit rate of 2048 kbit/s G.920G.929 Digital line transmission systems on cable at non-hierarchical bit rates G.930G.939 Digital line systems provided by FDM transmission bearers G.940G.949 Digital line systems G.950G.959 Digital section and digital t
6、ransmission systems for customer access to ISDN G.960G.969 Optical fibre submarine cable systems G.970G.979 Optical line systems for local and access networks G.980G.989 Metallic access networks G.990G.999 MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE GENERIC AND USER- RELATED ASPECTS G.1000G.1999 T
7、RANSMISSION 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 For further details, please refer to the list of ITU-T Recommendations. Rec. ITU-T G.993.5 (2015)/Amd.2 (12/2017) i Recommendation I
8、TU-T G.993.5 Self-FEXT cancellation (vectoring) for use with VDSL2 transceivers Amendment 2 Summary Vectoring is a transmission method that employs the coordination of line signals for reduction of crosstalk levels and improvement of performance. The degree of improvement depends on the channel char
9、acteristics. Vectoring may be for a single user or for multiple users benefit. Recommendation ITU-T G.993.5 is specifically limited to the self-far-end crosstalk (self-FEXT) cancellation in the downstream and upstream directions. It defines a single method of self-FEXT cancellation, in which FEXT ge
10、nerated by a group of near-end transceivers and interfering with the far-end transceivers of that same group is cancelled. This cancellation takes place between very high-bit-rate digital subscriber line 2 (VDSL2) transceivers, not necessarily of the same profile. This Recommendation is intended to
11、be implemented in conjunction with Recommendation ITU-T G.993.2. ITU-T G.993.5 (2015) consolidates ITU-T G.993.5 (2010) with all its amendments and corrigenda. Amendment 1 defines the following new functionality: Transceiver O-DEACTIVATING state. Amendment 2 adds Annex A: Mitigating strong FEXT; and
12、 Annex B: Vectored Long Reach VDSL2. History Edition Recommendation Approval Study Group Unique ID *1.0 ITU-T G.993.5 2010-04-22 15 11.1002/1000/10414 1.1 ITU-T G.993.5 (2010) Cor. 1 2011-06-22 15 11.1002/1000/11128 1.2 ITU-T G.993.5 (2010) Amd. 1 2011-12-16 15 11.1002/1000/11396 1.3 ITU-T G.993.5 (
13、2010) Cor. 2 2012-06-13 15 11.1002/1000/11643 1.4 ITU-T G.993.5 (2010) Amd. 2 2012-10-29 15 11.1002/1000/11796 1.5 ITU-T G.993.5 (2010) Amd. 3 2013-04-22 15 11.1002/1000/11889 1.6 ITU-T G.993.5 (2010) Amd. 4 2013-08-29 15 11.1002/1000/11993 1.7 ITU-T G.993.5 (2010) Amd. 5 2014-04-04 15 11.1002/1000/
14、12095 2.0 ITU-T G.993.5 2015-01-13 15 11.1002/1000/12372 2.1 ITU-T G.993.5 (2015) Cor. 1 2016-11-13 15 11.1002/1000/13089 2.2 ITU-T G.993.5 (2015) Amd. 1 2016-12-22 15 11.1002/1000/13121 2.3 ITU-T G.993.5 (2015) Amd. 2 2017-12-07 15 11.1002/1000/13307 _ *To access the Recommendation, type the URL ht
15、tp:/handle.itu.int/ in the address field of your web browser, followed by the Recommendations unique ID. For example, http:/handle.itu.int/11.1002/1000/11 830-en. ii Rec. ITU-T G.993.5 (2015)/Amd.2 (12/2017) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized a
16、gency 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 Recommendations on them with a vi
17、ew 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 approval of ITU-T Recommenda
18、tions 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 “Administration“ is used for concise
19、ness 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 compliance with the Recommendati
20、on 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 required of any party. IN
21、TELLECTUAL 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 no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights,
22、 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. However, implementers are c
23、autioned 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 2018 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission
24、of ITU. Rec. ITU-T G.993.5 (2015)/Amd.2 (12/2017) iii Table of Contents Page 1 Scope . 1 2 References . 1 3 Definitions 2 3.1 Terms defined elsewhere 2 3.2 Terms defined in this Recommendation . 2 4 Abbreviations and acronyms 3 5 Reference models 5 5.1 General . 5 5.2 Downstream vectoring 6 5.3 Upst
25、ream vectoring 7 6 CO-side requirements in a vectored group . 7 6.1 General . 7 6.2 Downstream vectoring requirements for the VTU-O . 9 6.3 Upstream vectoring requirements for the VTU-O 14 6.4 Requirements for the VCE . 14 7 CP-side requirements in a vectored group 14 7.1 General . 15 7.2 Downstream
26、 vectoring requirements for the VTU-R . 16 7.3 Upstream vectoring requirements for the VTU-R 27 7.4 Requirements for the NT system 28 8 Vectoring-specific eoc messages 29 8.1 eoc messages for backchannel configuration . 30 8.2 Pilot sequence update command and response . 34 8.3 Power management comm
27、ands and responses . 36 9 Activation and deactivation of pairs in a vectored group . 37 9.1 Orderly shutdown event . 37 9.2 Disorderly shutdown event . 37 10 Initialization of a vectored group 37 10.1 Overview 37 10.2 ITU-T G.994.1 Handshake phase . 41 10.3 Channel Discovery phase . 47 10.4 Training
28、 phase 57 10.5 Channel Analysis and Exchange phase 67 10.6 Transition from initialization to Showtime 67 10.7 Loop diagnostic mode procedures 68 iv Rec. ITU-T G.993.5 (2015)/Amd.2 (12/2017) Page 11 Configuration and test parameters 70 11.1 Configuration parameters . 70 11.2 Test parameters . 72 Anne
29、x A Mitigating strong FEXT 77 A.1 Introduction 77 A.2 Control parameters for the minimum message overhead data rate (amends clause 9.5.4 of ITU-T G.993.2) . 77 A.3 Clipped error samples . 77 A.4 OLR commands 78 A.5 ITU-T G.994.1 Handshake phase (amends clause 10.2) 79 A.6 TIGAV functionality 80 A.7
30、Main body amendments related to MREFPSD 89 A.8 Management . 102 Annex B Vectored long reach VDSL2 . 104 B.1 Introduction 104 B.2 Overview of the initialization procedure 104 B.3 ITU-T G.994.1 Handshake phase . 106 B.4 Signals sent by the VTU-O during the Channel Discovery and Training phase . 112 B.
31、5 Signals sent by the VTU-R during the Channel Discovery and Training phase . 115 B.6 O/R-P-PROBING-LR signal exchange 117 B.7 O/R-P-TRAINING-LR signal exchange 123 B.8 ITU-T G.993.5 Channel Discovery phase and Training phase in long loop operation . 130 B.9 Definition of limit PSD masks . 132 B.10
32、Management . 133 B.11 Nominal aggregate transmit power (NOMATP) (replaces clause 10.3.4.2.1 of ITU-G.993.2) 136 Appendix I Crosstalk channel modelling 137 I.1 Scope 137 I.2 Purpose . 137 I.3 MIMO crosstalk channel model A . 137 I.4 MIMO crosstalk channel model C . 137 Appendix II Examples of VCE con
33、trol of initialization process in the activation of multiple lines in the vectored group . 141 II.1 Introduction 141 II.2 VCE handling two groups of initializing lines . 141 II.3 VCE using handshake capabilities . 144 Rec. ITU-T G.993.5 (2015)/Amd.2 (12/2017) v Page Appendix III SNR-based FEXT chann
34、el estimation method 145 III.1 Tools . 145 III.2 Estimation of FEXT channels from a new line into existing lines . 145 III.3 Estimation of FEXT channels from existing lines into a new line . 151 Bibliography. 156 Rec. ITU-T G.993.5 (2015)/Amd.2 (12/2017) 1 Recommendation ITU-T G.993.5 Self-FEXT canc
35、ellation (vectoring) for use with VDSL2 transceivers Amendment 2 Editorial note: This is a complete-text publication that includes ITU-T G.993.5 (2015) plus its Amendment 1 (2016), Corrigendum 1 (2016) and Amendment 2 (2017). Annexes A and B, introduced by Amendment 2, are not shown in revision mark
36、s for readability purposes. 1 Scope Vectoring is a transmission method that employs the coordination of line signals for reduction of crosstalk levels and improvement of performance. The degree of improvement depends on the channel characteristics. Vectoring may be for a single user or for multiple
37、users benefit. This Recommendation is specifically limited to the self-far-end crosstalk (self-FEXT) cancellation in the downstream and upstream directions. This Recommendation defines a single method of self- FEXT cancellation, in which far-end crosstalk (FEXT) generated by a group of near-end tran
38、sceivers and interfering with the far-end transceivers of that same group is cancelled. This cancellation takes place between very high-bit-rate digital subscriber line 2 (VDSL2) transceivers, not necessarily of the same profile. This Recommendation is intended to be implemented in conjunction with
39、ITU-T G.993.2. Multi-pair digital subscriber line (DSL) bonding (b-ITU-T G.998.1, b-ITU-T G.998.2 and b-ITU-T G.998.3) may be implemented in conjunction with vectoring. The techniques described in this Recommendation provide means of reducing self-FEXT generated by the transceivers in a multi-pair c
40、able or cable binder. Self-FEXT cancellation techniques are particularly beneficial with short cable lengths ( 1 km) and limited near-end crosstalk (NEXT), background noise, and FEXT from systems which are not a part of the vectored group (alien noise). The level of non-self-FEXT noise sources relat
41、ive to that of self-FEXT sources determines the degree to which self-FEXT reduction can improve performance. Another significant factor is the degree to which the self-FEXT cancelling system has access to the disturbing pairs of the cable. Maximum gains are achieved when the self-FEXT cancelling sys
42、tem has access to all of the pairs of a cable carrying broadband signals. For multi-binder cables, significant gains are possible when the self-FEXT cancelling system has access to all of the pairs of the binder group(s) in which it is deployed and has the ability to cancel at least the majority of
43、dominant self-FEXT disturbers within the binder. When multiple self-FEXT cancelling systems are deployed in a multi-binder cable without binder management, gains may be significantly reduced. 2 References The following ITU-T Recommendations and other references contain provisions which, through refe
44、rence 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 to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most
45、 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 within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. ITU-T G.993.2 Reco
46、mmendation ITU-T G.993.2 (2006), Very high speed digital subscriber line transceivers 2 (VDSL2). 2 Rec. ITU-T G.993.5 (2015)/Amd.2 (12/2017) ITU-T G.994.1 Recommendation ITU-T G.994.1 (2007), Handshake procedures for digital subscriber line transceivers, plus Amd. 5 (2010). ITU-T G.997.1 Recommendat
47、ion ITU-T G.997.1 (2009), Physical layer management for digital subscriber line transceivers, plus Amd. 1 (2010). ITU-T G.998.4 Recommendation ITU-T G.998.4 (2010), Improved impulse noise protection for DSL transceivers. IEEE 802.3 IEEE 802.3 (2008), IEEE Standard for Information technology Telecomm
48、unications and information exchange between systems Local and metropolitan area networks Specific requirements Part 3: Carrier Sense Multiple Access with Collision Detection (CSMA/CD) Access Method and Physical Layer Specifications. 3 Definitions 3.1 Terms defined elsewhere This Recommendation adopt
49、s the definitions of ITU-T G.993.2. 3.2 Terms defined in this Recommendation This Recommendation defines the following terms: 3.2.1 backchannel: The channel through which the VTU-R sends clipped error samples to the vectoring control entity (VCE). The backchannel may be implemented as part of the eoc or as part of the Ethernet data stream from the VTU-R to the VTU-O. 3.2.2 ceiling: Rounding to the nearest higher integer, denoted as x . 3.2.3 channel matrix: For a particular line in a group of
