1、 International Telecommunication Union ITU-T G.992.3TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU Amendment 3(11/2010) 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 3: Scale factor for downstream transmitter referred virtual noise, and corrigenda Recommendation ITU-T G.992.3 (2009) Amendment 3 ITU-T G-SERIES RECOMMENDATIONS TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS G.100G.199 G
3、ENERAL CHARACTERISTICS COMMON 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 INTERCONNE
4、CTION WITH METALLIC LINES G.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.90
5、9 Parameters for optical fibre 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 Di
6、gital line systems G.950G.959 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 Access networks G.990G.999MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE
7、 GENERIC AND USER-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
8、.992.3 (2009)/Amd.3 (11/2010) i Recommendation ITU-T G.992.3 Asymmetric digital subscriber line transceivers 2 (ADSL2) Amendment 3 Scale factor for downstream transmitter referred virtual noise, and corrigenda Summary Amendment 3 to Recommendation ITU-T G.992.3 covers the following functionalities:
9、Channel initialization policies (corrigendum). Upstream optional D0 values (corrigendum). Scale factor for downstream transmitter referred virtual noise (new functionality). Loop diagnostics procedures (editorial). History Edition Recommendation Approval Study Group 1.0 ITU-T G.992.3 2002-07-29 15 1
10、.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 G.992.3
11、 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 ITU-T G.9
12、92.3 (2009) Cor. 1 2009-11-13 15 3.2 ITU-T G.992.3 (2009) Amend. 1 2010-03-01 15 3.3 ITU-T G.992.3 (2009) Amend. 2 2010-07-29 15 3.4 ITU-T G.992.3 (2009) Amend. 3 2010-11-29 15 ii Rec. ITU-T G.992.3 (2009)/Amd.3 (11/2010) FOREWORD The International Telecommunication Union (ITU) is the United Nations
13、 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 Recommendations on
14、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 approval of IT
15、U-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 “Administration“ is us
16、ed 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 compliance with th
17、e 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 required of
18、 any party. INTELLECTUAL 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 Pr
19、operty 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. However, impl
20、ementers 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 2011 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior writt
21、en permission of ITU. Rec. ITU-T G.992.3 (2009)/Amd.3 (11/2010) iii CONTENTS Page 1) Channel initialization policies (correction) 1 2) Upstream optional D0 values (correction) 1 3) Scale factor for TXREFVNds (new functionality) . 6 4) Loop diagnostics procedures 11 Rec. ITU-T G.992.3 (2009)/Amd.3 (1
22、1/2010) 1 Recommendation ITU-T G.992.3 Asymmetric digital subscriber line transceivers 2 (ADSL2) Amendment 3 Scale factor for downstream transmitter referred virtual noise, and corrigenda 1) Channel initialization policies (correction) In ITU-T G.992.3 Amendment 1 clause 7.10.3, indicate the followi
23、ng paragraph as deleted text: This change also applies to ITU-T G.992.5 by normative reference to ITU-T G.992.3. 7.10.3 Exchange phase If the CO-MIB sets CIPOLICY (see clause 7.3.2.10 of ITU-T G.997.1) to ONE for a bearer channel, it shall have the minimum net data rate (see clause 7.3.2.1.1 of ITU-
24、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). 2) Upstream optional D0 values (correction) a) Change Table 7-8 in clause 7.6.2 as follows (align with ITU-T G.994.1): 7.6.2 V
25、alid framing configurations Table 7-8 Valid framing configurations Parameter Capability Dp For downstream latency paths: 1, 2, 4, 8, 16, 32, 64. For the downstream latency path #0, additional valid D0values are: 96, 128, 160, 192, 224, 256, 288, 320, 352, 384, 416, 448, 480, 511. For upstream latenc
26、y paths: 1, 2, 4, 8. For the upstream latency path #0, additional valid D0values are: 16, 32, 64. If Rp= 0 then Dp= 1 b) Change one paragraph in clause 7.7.1.5 as follows: (revision marks shown are relative to the change made in Corrigendum 1) This change also applies to ITU-T G.992.5 by normative r
27、eference to ITU-T G.992.3. 2 Rec. ITU-T G.992.3 (2009)/Amd.3 (11/2010) 7.7.1.5 Interleaver With Dpone of the mandatory values identified in Table 7-9, Table 7-10, Table 7-11 or Table 7-12, and with the above-defined rule, the output octets from the interleaver always occupy distinct time slots when
28、NFEC.pis odd and Dpis a power of 2. When NFEC.pis even, a dummy octet shall be added at the beginning of the codeword at the input to the interleaver. The resultant odd-length codeword is then convolutionally interleaved, and the dummy octet shall then be removed from the output of the interleaver.
29、With D0one of the optional (i.e., valid as identified in Table 7-8, but not mandatory as identified in Table 7-9 for downstream, or Table 7-10 for upstream, Table 7-11 or Table 7-12) values, the codeword length NFEC.0and D0shall be co-prime (i.e., have no common divisors except for 1). No dummy octe
30、ts shall be used, as with the above-defined rule, the output octets from the interleaver always occupy distinct time slots. c) Change clause 7.10.1.1 as follows (align with ITU-T G.994.1): 7.10.1.1 ITU-T G.994.1 capabilities list message The following information about the PMS-TC function shall be a
31、s defined in ITU-T G.994.1 as part of the CL and CLR messages. This information may be optionally requested and reported via ITU-T G.994.1 messages at the start of a session. However, the information shall be exchanged at least once between ATU-C and ATU-R but not necessarily at the start of each se
32、ssion. The information exchanged includes: capability to transport NTR (downstream only); support for erasure decoding reporting; minimum downstream message-based overhead channel data rate that is needed; minimum upstream message-based overhead channel data rate that is needed; maximum downstream n
33、et data rate of each latency path can be supported; maximum upstream net data rate of each latency path that can be supported; Rp maxon each optional latency path that can be supported; Dp maxon each optional latency path that can be supported. In addition, non-standard capabilities may be reported
34、through additional non-standard facility (NSF) messages. This information is represented using an ITU-T G.994.1 tree model of the information as in Table 7-18. An ATU provides both the upstream and downstream information in response to the capabilities request message. The latency paths supported sh
35、all start from 0 and increase by one. The capability list shall indicate that latency paths supported consists of #0, #0, #1, #0, #1, #2 or #0, #1, #2, #3 (there are only 4 cases). The number of latency paths supported may be different for upstream and downstream. Rec. ITU-T G.992.3 (2009)/Amd.3 (11
36、/2010) 3 Table 7-18 Format for PMS-TC capability list information Npar(2) bit Definition of Npar(2) bit NTR This bit is set to ONE if the ATU has the capability to transport the NTR signal in the downstream direction. Erasure decoding reporting This bit is set to ONE if the ATU supports reporting in
37、 R-PARAMS message as to whether or not erasure decoding is being used on the downstream latency paths. Spar(2) bit Definition of related Npar(3) octets Downstream overhead data rate Parameter block of 2 octets that describes the minimum message-based data rate that is needed by the ATU. The unsigned
38、 6-bit value is the data rate divided by 1000 bits per second minus 1 (covering the range 1 to 64 kbit/s) see Note. Upstream overhead data rate Parameter block of 2 octets that describes the minimum message-based data rate that is needed by the ATU. The unsigned 6-bit value is the data rate divided
39、by 1000 bits per second minus 1 (covering the range 1 to 64 kbit/s) see Note. Downstream PMS-TC latency path #0 supported (always set to 1) Parameter block of 6 octets that describes the maximum net_max downstream rate, downstream S0min, and downstream D0values supported in the latency path #0. The
40、unsigned 12-bit net_max value is the data rate divided by 4000. The net_max downstream rate shall be greater than or equal to the maximum required downstream data rate for each TPS-TC type that is supported by the ATU. The supported range of S0values shall be indicated by its lower bound S0min. S0mi
41、nshall equal 1/(n+1), with n coded as an unsigned 4-bit value in the 1 to 15 range. The D0values supported shall be individually indicated with 1 bit per value. Upstream PMS-TC latency path #0 supported (always set to 1) Parameter block of 3 octets that describes the maximum net_max upstream rate an
42、d downupstream D0maxvalues supported in the latency path #0. The unsigned 12-bit net_max value is the data rate divided by 4000. The net_max upstream rate shall be greater than or equal to the maximum required upstream data rate for each TPS-TC type that is supported by the ATU. D0maxis represented
43、as an unsigned 4-bit value n, with D0max= 8 + 4 n, and n = 0, 2, 6, or 14. The D0values supported shall be individually indicated with 1 bit per value. Downstream PMS-TC latency path #1 supported Parameter block of 4 octets that describes the maximum net_max downstream rate, downstream R1max, and do
44、wnstream D1max supported in the latency path #1. The unsigned 12-bit net_max value is the data rate divided by 4000. R1maxis an unsigned 4-bit value and shall be one of the valid Rpvalues divided by 2. D1maxis an unsigned 3-bit value and shall be the logarithm base 2 of one of the valid Dpvalues. Up
45、stream PMS-TC latency path #1 supported Parameter block of 4 octets that describes the maximum net_max upstream rate, upstream R1max, and upstream D1maxsupported in the latency path #1. The unsigned 12-bit net_max value is the data rate divided by 4000. R1maxis an unsigned 4-bit value and shall be o
46、ne of the valid Rpvalues divided by 2. D1maxis an unsigned 3-bit value and shall be the logarithm base 2 of one of the valid Dpvalues. Downstream PMS-TC latency path #2 supported Parameter block of 4 octets that describes the maximum net_max downstream rate, downstream R2max, and downstream D2maxsup
47、ported in the latency path #2. The unsigned 12-bit net_max value is the data rate divided by 4000. R2maxis an unsigned 4-bit value and shall be one of the valid Rpvalues divided by 2. D2maxis an unsigned 3-bit value and shall be the logarithm base 2 of one of the valid Dpvalues. Upstream PMS-TC late
48、ncy path #2 supported Parameter block of 4 octets that describes the maximum net_max upstream rate, upstream R2max, and upstream D2maxsupported in the latency path #2. The unsigned 12-bit net_max value is the data rate divided by 4000. R2maxis an unsigned 4-bit value and shall be one of the valid Rp
49、values divided by 2. D2maxis an unsigned 3-bit value and shall be the logarithm base 2 of one of the valid Dpvalues. 4 Rec. ITU-T G.992.3 (2009)/Amd.3 (11/2010) Table 7-18 Format for PMS-TC capability list information Spar(2) bit Definition of related Npar(3) octets Downstream PMS-TC latency path #3 supported Parameter block of 4 octets that describes the maximum net_max downstream rate, downstream R3max, and downstream D3maxsupported in the latency path #3. The unsigned 12-bit net_max va
