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.993.5 TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU Amendment 1 (12/2016) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS Digital sections and digital line system Metallic access networks Self-FEX
2、T cancellation (vectoring) for use with VDSL2 transceivers Amendment 1 Recommendation ITU-T G.993.5 (2016) Amendment 1 ITU-T G-SERIES RECOMMENDATIONS TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS G.100G.199 GENERAL CHARACTERISTICS COMMO
3、N TO ALL ANALOGUE 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.
4、400G.449 COORDINATION 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 General G.900G.909 Parameters for optical fib
5、re cable systems G.910G.919 Digital 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.95
6、9 Digital section and digital transmission 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-
7、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 For further details, please refer to the list of ITU-T Recommendations. Rec. ITU-T G.993.5 (2016)/Amd.
8、1 (12/2016) i Recommendation ITU-T G.993.5 Self-FEXT cancellation (vectoring) for use with VDSL2 transceivers Amendment 1 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 improveme
9、nt depends on the channel characteristics. 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
10、cancellation, in which FEXT generated 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
11、Recommendation is intended to be implemented in conjunction with Recommendation ITU-T G.993.2. This version of this Recommendation integrates all of the previous amendments and corrigenda with the 2010 version 1.0 of Recommendation ITU-T G.993.5. This Amendment 1 defines the following new functional
12、ity: 1. Transceiver O-DEACTIVATING state 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
13、.5 (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 11.1002/1
14、000/12095 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 _ * To access the Recommendation, type the URL http:/handle.itu.int/ in the address field of your web browser,
15、 followed by the Recommendations unique ID. For example, http:/handle.itu.int/11.1002/1000/11830-en. ii Rec. ITU-T G.993.5 (2016)/Amd.1 (12/2016) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and comm
16、unication 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 view to standardizing telecommunications on a worldwide basis. T
17、he 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 Recommendations is covered by the procedure laid down in WTSA Resolution
18、 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 conciseness to indicate both a telecommunication administration and a
19、 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 Recommendation is achieved when all of these mandatory provisions are met.
20、 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. INTELLECTUAL PROPERTY RIGHTSITU draws attention to the possibili
21、ty 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, whether asserted by ITU members or others outside of the Recom
22、mendation 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 cautioned that this may not represent the latest information and
23、 are therefore strongly urged to consult the TSB patent database at http:/www.itu.int/ITU-T/ipr/. ITU 2017 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.993.5 (2016)/Amd.1 (12/2016) iii Table of
24、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 4 5.1 General . 4 5.2 Downstream vectoring 5 5.3 Upstream vectoring 6 6 CO-side requirements in a vectored group . 6
25、 6.1 General . 6 6.2 Downstream vectoring requirements for the VTU-O . 8 6.3 Upstream vectoring requirements for the VTU-O 13 6.4 Requirements for the VCE . 13 7 CP-side requirements in a vectored group 13 7.1 General . 14 7.2 Downstream vectoring requirements for the VTU-R . 15 7.3 Upstream vectori
26、ng requirements for the VTU-R 26 7.4 Requirements for the NT system 27 8 Vectoring-specific eoc messages 28 8.1 eoc messages for backchannel configuration . 29 8.2 Pilot sequence update command and response . 33 8.3 Power management commands and responses . 35 9 Activation and deactivation of pairs
27、in a vectored group . 36 9.1 Orderly shutdown event . 36 9.2 Disorderly shutdown event . 36 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 phase 57 10.5 Channel Analysis and Exchange phase 67 10.6 Tran
28、sition from initialization to Showtime 67 10.7 Loop diagnostic mode procedures 68 iv Rec. ITU-T G.993.5 (2016)/Amd.1 (12/2016) Page 11 Configuration and test parameters 70 11.1 Configuration parameters . 70 11.2 Test parameters . 72 Appendix I Crosstalk channel modelling 77 I.1 Scope 77 I.2 Purpose
29、. 77 I.3 MIMO crosstalk channel model A . 77 I.4 MIMO crosstalk channel model C . 77 Appendix II Examples of VCE control of initialization process in the activation of multiple lines in the vectored group . 81 II.1 Introduction 81 II.2 VCE handling two groups of initializing lines . 81 II.3 VCE usin
30、g handshake capabilities . 84 Appendix III SNR-based FEXT channel estimation method 85 III.1 Tools . 85 III.2 Estimation of FEXT channels from a new line into existing lines . 85 III.3 Estimation of FEXT channels from existing lines into a new line . 91 Bibliography. 96 Rec. ITU-T G.993.5 (2016)/Amd
31、.1 (12/2016) 1 Recommendation ITU-T G.993.5 Self-FEXT cancellation (vectoring) for use with VDSL2 transceivers Amendment 1 Editorial note: This is a complete-text publication. Modifications introduced by this amendment are shown in revision marks relative to Recommendation ITU-T G.993.5 (2015) plus
32、its Corrigendum 1. 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 users ben
33、efit. 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 transceivers a
34、nd 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 ITU-T G.99
35、3.2. 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 cable or ca
36、ble 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 relative to tha
37、t 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 system has ac
38、cess 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 dominant s
39、elf-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 reference in t
40、his 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 recent ed
41、ition 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 Recommendation
42、 ITU-T G.993.2 (2006), Very high speed digital subscriber line transceivers 2 (VDSL2). ITU-T G.994.1 Recommendation ITU-T G.994.1 (2007), Handshake procedures for digital subscriber line transceivers, plus Amd. 5 (2010). 2 Rec. ITU-T G.993.5 (2016)/Amd.1 (12/2016) ITU-T G.997.1 Recommendation ITU-T
43、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 Telecommunications
44、 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 adopts the defi
45、nitions 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 pa
46、rt 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 lines, the channel matrix characterizes the FEXT couplings on each subcarrier frequency between the line and all
47、 other lines in the group. 3.2.4 clipped error sample: A (B_max+1)-bit 2s complement representation of a normalized error sample through multiplying each component by 2N_max1, flooring and clipping to the 2B_max, 2B_max 1 interval (with N_max a fixed value, and B_max a value controlled by the VCE).
48、3.2.5 expected throughput (ETR): see clause 3.2 of ITU-T G.998.4. 3.2.6 flag tones: All subcarriers of a sync symbol with indices equal to 10n+1 or 10n+7, with n an integer value. Flag tones are used to signal OLR transitions during Showtime. 3.2.7 flooring: Rounding to the nearest lower integer, de
49、noted as x . 3.2.8 normalized error sample: The complex error measured by the VTU-R, being the distance between the received signal vector and the decision constellation point referred to the input of the constellation descrambler, expressed in units equal to half the distance between two adjacent constellation points. 3.2.9 pilot sequence: A binary sequence set by the VCE. When the pilot sequence is transmitted during initialization and in Showtime, each bit of the
