1、 International Telecommunication Union ITU-T G.992.3TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU Amendment 1(03/2010) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS Digital sections and digital line system Access networks Asymmetric digital subscriber line transceivers 2 (
2、ADSL2) Amendment 1: Channel initialization policies Recommendation ITU-T G.992.3 (2009) 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 COMMON TO ALL ANALOGUE C
3、ARRIER-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 COORDINATI
4、ON 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 fibre cable systems G.
5、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.959 Digital section a
6、nd 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 Access networks G.990G.999MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE GENERIC AND USER-RELATED ASPECTS G.1000G.1999
7、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.992.3 (2009)/Amd.1 (03/2010) i Recommendation
8、ITU-T G.992.3 Asymmetric digital subscriber line transceivers 2 (ADSL2) Amendment 1 Channel initialization policies Summary Amendment 1 to Recommendation ITU-T G.992.3 contains initialization policies (new functionality). History Edition Recommendation Approval Study Group 1.0 ITU-T G.992.3 2002-07-
9、29 15 1.1 ITU-T G.992.3 (2002) Amend. 1 2003-05-22 15 1.2 ITU-T G.992.3 (2002) Cor. 1 2003-12-14 15 1.3 ITU-T G.992.3 (2002) Cor. 2 2004-02-22 15 1.4 ITU-T G.992.3 (2002) Amend. 2 2004-04-30 15 1.5 ITU-T G.992.3 (2002) Amend. 3 2004-06-13 15 1.6 ITU-T G.992.3 (2002) Amend. 4 2004-06-13 15 2.0 ITU-T
10、G.992.3 2005-01-13 15 2.1 ITU-T G.992.3 (2005) Amend. 1 2005-09-22 15 2.2 ITU-T G.992.3 (2005) Amend. 2 2006-03-29 15 2.3 ITU-T G.992.3 (2005) Amend. 3 2006-12-14 15 2.4 ITU-T G.992.3 (2005) Amend. 4 2007-07-29 15 2.5 ITU-T G.992.3 (2005) Amend. 5 2008-06-22 15 3.0 ITU-T G.992.3 2009-04-22 15 3.1 IT
11、U-T G.992.3 (2009) Cor. 1 2009-11-13 15 3.2 ITU-T G.992.3 (2009) Amend. 1 2010-03-01 15 ii Rec. ITU-T G.992.3 (2009)/Amd.1 (03/2010) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication tec
12、hnologies (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. The World Tele
13、communication 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 1. In some a
14、reas 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 recognized o
15、perating 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. The words “sh
16、all“ 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 RIGHTS ITU draws attention to the possibility that the p
17、ractice 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 Recommendation dev
18、elopment 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 are therefor
19、e strongly urged to consult the TSB patent database at http:/www.itu.int/ITU-T/ipr/. ITU 2010 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.992.3 (2009)/Amd.1 (03/2010) 1 Recommendation ITU-T G.9
20、92.3 Asymmetric digital subscriber line transceivers 2 (ADSL2) Amendment 1 Channel initialization policies Change clause 7.10.3 (Exchange phase) as follows: 7.10.3 Exchange phase Within these constraints, the receiver shall select the values so as to optimize in the priority configured through the C
21、O-MIB channel initialization policy parameter (CIPOLICY, see clause 7.3.2.10 of ITU-T G.997.1). The channel initialization policy applies only for the selection of the values exchanged in the PARAMS message during initialization, and does not apply during showtime. The following channel initializati
22、on policies are defined: Policy ZERO: if CIpolicyn= 0, then: 1) Maximize net data rate for bearer channel #n, per the allocation of the net data rate, in excess of the sum of the minimum net data rates over all bearer channels (see clause 7.10.2). 2) Minimize excess margin with respect to the maximu
23、m noise margin MAXSNRM through gain scalings (see clause 8.6.4). Other control parameters may be used to achieve this (e.g., PCB see clause 8.13.3). Policy ONE: if CIpolicyn= 1, then: a) If the minimum net data rate (see clause 7.3.2.1.1 of ITU-T G.997.1) is set equal to the maximum net data rate (s
24、ee clause 7.3.2.1.3 of ITU-T G.997.1), then: 1) Maximize INP_actnfor the bearer channel #n. b) If the minimum net data rate (see clause 7.3.2.1.1 of ITU-T G.997.1) is not set equal to the maximum net data rate (see clause 7.3.2.1.3 of ITU-T G.997.1), then: 1) Maximize net data rate for all the beare
25、r channels, per the allocation of the net data rate, in excess of the sum of the minimum net data rates over all bearer channels (see clause 7.10.2). 2) If such maximized net data rate is equal to the maximum net data rate (see clause 7.3.2.1.3 of ITU-T G.997.1), maximize INP_actnfor the bearer chan
26、nel #n. 3) Minimize excess margin with respect to the maximum noise margin MAXSNRM through gain scalings (see clause 8.6.4). Other control parameters may be used to achieve this (e.g., PCB, see clause 8.13.3). Policy TWO if CIpolicyn= 2, then: 1) Maximize net data rate for all the bearer channels, p
27、er the allocation of the net data rate, in excess of the sum of the minimum net data rates over all bearer channels (see clause 7.10.2). 2 Rec. ITU-T G.992.3 (2009)/Amd.1 (03/2010) 2) If such maximized net data rate is equal to the maximum net data rate (see clause 7.3.2.1.3 of ITU-T G.997.1), maxim
28、ize SNRMnfor the bearer channel #n. 3) Minimize excess margin with respect to the maximum noise margin MAXSNRM through gain scalings (see clause 8.6.4). Other control parameters may be used to achieve this (e.g., PCB, see clause 8.13.3). If the CO-MIB sets CIPOLICY (see clause 7.3.2.10 of ITU-T G.99
29、7.1) to ONE for a bearer channel, it shall have the minimum net data rate (see clause 7.3.2.1.1 of ITU-T G.997.1) set equal to the maximum net data rate (see clause 7.3.2.1.3 of ITU-T G.997.1) and shall have the MAXSNRM set to infinity (see clause 7.3.1.3.3 of ITU-T G.997.1). If only a single bearer
30、 channel is configured through the CO-MIB, then the CIPOLICY shall be set to ZERO, or ONE or TWO for the bearer channel. If multiple bearer channels are configured through the CO-MIB, then the CIPOLICY shall be set to ZERO for each of the bearer channels. The use of channel initialization policy ONE
31、 or TWO with multiple bearer channels is for further study. Support of channel initialization policy ZERO is mandatory. Support of channel initialization policy ONE and TWO is optional. Additional channel initialization policies are for further study. The CIpolicynparameter values other than 0, and
32、1 and 2 are reserved for use by ITU-T. Printed in Switzerland Geneva, 2010 SERIES OF ITU-T RECOMMENDATIONS Series A Organization of the work of ITU-T Series D General tariff principles Series E Overall network operation, telephone service, service operation and human factors Series F Non-telephone t
33、elecommunication services Series G Transmission systems and media, digital systems and networks Series H Audiovisual and multimedia systems Series I Integrated services digital network Series J Cable networks and transmission of television, sound programme and other multimedia signals Series K Prote
34、ction against interference Series L Construction, installation and protection of cables and other elements of outside plant Series M Telecommunication management, including TMN and network maintenance Series N Maintenance: international sound programme and television transmission circuits Series O S
35、pecifications of measuring equipment Series P Terminals and subjective and objective assessment methods Series Q Switching and signalling Series R Telegraph transmission Series S Telegraph services terminal equipment Series T Terminals for telematic services Series U Telegraph switching Series V Data communication over the telephone network Series X Data networks, open system communications and security Series Y Global information infrastructure, Internet protocol aspects and next-generation networks Series Z Languages and general software aspects for telecommunication systems
