1、 International Telecommunication Union ITU-T G.993.2TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU Amendment 2(12/2012) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS Digital sections and digital line system Access networks Very high speed digital subscriber line transceiver
2、s 2 (VDSL2) Amendment 2 Recommendation ITU-T G.993.2 (2011) 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-TRANSMISSION SYSTEMS
3、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 RADIOTELEPHONY AND LIN
4、E 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 Digital sections at
5、 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 transmission syst
6、ems 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 TRANSMISSION MEDIA CHARACTER
7、ISTICS 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.993.2 (2011)/Amd.2 (12/2012) i Recommendation ITU-T G.993.2 Very high spee
8、d digital subscriber line transceivers 2 (VDSL2) Amendment 2 Summary Amendment 2 to Recommendation ITU-T G.993.2 (2011) covers the following functionalities: 1. Electrical length estimation method (corrigendum). 2. INPMIN-ROC (corrigendum). 3. Accuracy of test parameters (adding functionality). 4. I
9、NM facility (corrigendum). 5. O-SIGNATURE field for Upstream FDPS descriptor (new functionality). 6. SRA after SOS (corrigendum). 7. Annex B (Region B Europe) (corrigendum and adding functionality). 8. Annex Y with optional “pilot sequence length multiple of 4“ (corrigendum) and optional FDPS (new f
10、unctionality). History Edition Recommendation Approval Study Group 1.0 ITU-T G.993.2 2006-02-17 15 1.1 ITU-T G.993.2 (2006) Cor. 1 2006-12-14 15 1.2 ITU-T G.993.2 (2006) Amd. 1 2007-04-06 15 1.3 ITU-T G.993.2 (2006) Amd. 1 Cor. 1 2007-07-29 15 1.4 ITU-T G.993.2 (2006) Cor. 2 2007-07-29 15 1.5 ITU-T
11、G.993.2 (2006) Amd. 2 2008-02-06 15 1.6 ITU-T G.993.2 (2006) Amd. 3 2008-08-22 15 1.7 ITU-T G.993.2 (2006) Amd. 4 2009-01-13 15 1.8 ITU-T G.993.2 (2006) Cor. 3 2009-06-29 15 1.9 ITU-T G.993.2 (2006) Amd. 5 2010-04-22 15 1.10 ITU-T G.993.2 (2006) Amd. 6 2010-11-29 15 1.11 ITU-T G.993.2 (2006) Cor. 4
12、2011-04-13 15 1.12 ITU-T G.993.2 (2006) Amd. 7 2011-06-22 15 2.0 ITU-T G.993.2 2011-12-16 15 2.1 ITU-T G.993.2 (2011) Amd. 1 2012-04-06 15 2.2 ITU-T G.993.2 (2011) Cor. 1 2012-06-13 15 2.3 ITU-T G.993.2 (2011) Amd. 2 2012-12-07 15 ii Rec. ITU-T G.993.2 (2011)/Amd.2 (12/2012) FOREWORD The Internation
13、al Telecommunication Union (ITU) is the United 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, operatin
14、g and tariff questions and issuing Recommendations 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, produ
15、ce Recommendations on these topics. The approval 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
16、 Recommendation, the expression “Administration“ 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., int
17、eroperability or applicability) and compliance 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
18、that compliance with the Recommendation is required of 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
19、, validity or applicability of claimed Intellectual 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 re
20、quired to implement this Recommendation. However, 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 2013 All rights reserved. No part of this publication may be reprod
21、uced, by any means whatsoever, without the prior written permission of ITU. Rec. ITU-T G.993.2 (2011)/Amd.2 (12/2012) iii Table of Contents Page 1) Electrical length estimation method . 1 1.1) Clause 7.2.1.3.2.1 . 1 2) INPMIN-ROC 1 2.1) Clause 10.4.4 1 2.2) Clause 12.3.5.2.1.1 . 2 2.3) Clause 9.6 .
22、2 2.4) Clause 11.4.1.1.10 3 2.5) Clause 12.3.5.2.1.1 . 3 3) Accuracy of test parameters 4 3.1) Clause 11.4.1.2 . 4 4) INM facility 7 4.1) Clause 11.2.3.13 . 7 4.2) Clause 11.3.4.1 . 10 4.3) Clause 11.4.2.2.6 10 4.4) Clause 12.3.5.2.1.1 . 11 4.5) Clause 12.3.5.2.2.1 . 13 5) O-SIGNATURE field for Upst
23、ream FDPS descriptor . 14 5.1) Table 12-21, Fields #23 and #24 14 5.2) Table 12-21, Fields #20 and #21 14 5.3) Table 12-21, Field #24 . 15 6) SRA following SOS 16 6.1) Clause 13.4.4 16 7) Annex B 16 8) Annex O 36 8.1) Clause O.1 36 Rec. ITU-T G.993.2 (2011)/Amd.2 (12/2012) 1 Recommendation ITU-T G.9
24、93.2 Very high speed digital subscriber line transceivers 2 (VDSL2) Amendment 2 1) Electrical length estimation method 1.1) Clause 7.2.1.3.2.1 Change clause 7.2.1.3.2.1 as follows: 7.2.1.3.2.1 Electrical length estimation method Two methods are defined for deriving the electrical length autonomously
25、: ELE-M0 the default method ELE-M1 the alternative method Implementation of ELE-M0 is mandatory. Implementation of ELE-M1 is optional. The ELE-M1 shall be used if the CO-MIB parameter “Alternative Electrical Length Estimation Mode“ (AELE-MODE) is set to a value of 1 or higher, and the mode is suppor
26、ted by the VTU-O and by the VTU-R. Otherwise, the ELE-M0 shall be used. The actual AELE-MODE used shall be reported in CO-MIB parameter “Actual Alternative Electrical Length Estimation Mode“ (ACT-AELE-MODE). If the VTU-O supports the optional ELE-M1 and the ELE-M0 is used, then the ACT-AELE-MODE par
27、ameter shall be set to a value of 0. 2) INPMIN-ROC 2.1) Clause 10.4.4 Change clause 10.4.4 as follows: 10.4.4 Cyclic extension and windowing For a given setting of the CE length and window length , the DMT symbols will be transmitted at a symbol rate equal to: CECSCPDMTLNfNLLNfNf+=+=2222If the CE le
28、ngth corresponds to m = 5, this results in symbol rates of 4 ksymbols/s for f = 4.3125 kHz and 8 ksymbols/s for f = 8.625 kHz, independent of the sampling rate used. The data symbol rate is equal to: 25725622+=CSCPsLLNfNfThe equivalent 4k DMT symbol length (denoted as T4k) is defined as: 2 Rec. ITU-
29、T G.993.2 (2011)/Amd.2 (12/2012) DMTkfT14= for f = 4.3125 kHz, and DMTkfT24= for f = 8.625 kHz. If the CE length corresponds to m = 5, this results in an equivalent 4k DMT symbol length of 250 s, independent of the subcarrier spacing and sampling rate used. 2.2) Clause 12.3.5.2.1.1 Change clause 12.
30、3.5.2.1.1 as follows: 12.3.5.2.1.1 O-MSG 1 Field #23 contains the value of INPMIN-ROC-ds as specified in the MIB. The parameter is defined as the required INP_no_erasure value for the ROC (see clause 9.6). INPMIN-ROC-ds is an integer in the range from 0 to 8 and is expressed in multiples of T4k, wit
31、h T4kdefined in clause 10.4.4. 2.3) Clause 9.6 Modify clause 9.6 as follows: 9.6 Impulse noise protection (INPp) INPp(impulse noise protection for latency path p) is defined as the number of consecutive DMT symbols or fractions thereof, as seen at the input to the de-interleaver, for which errors ca
32、n be completely corrected by the error correcting code, regardless of the number of errors within the errored DMT symbols. NOTE 1 This is equivalent to the number of consecutive errored octets within any block of (Ip 1)Dp+ 1 octets, as seen at the input to the de-interleaver, for which errors can be
33、 completely corrected by the error correcting code, divided by Lp/8, the number of octets loaded in a DMT symbol for latency path p. The interleaver block length, Ip, and interleaver depth, Dp, are defined in clause 9.4, and the number of bits from latency path p loaded into a DMT symbol, Lp, is def
34、ined in clause 9.5.4. NOTE 2 The value of INPpis given in terms of DMT symbols. The time span of impulse noise protection, in ms, varies with subcarrier spacing as determined by the profile (see clause 6) and with the CE length (see clause 10.4.4). The actual impulse noise protection INP_actnof bear
35、er channel #n shall always be set to the value of the derived parameter INPpof the underlying PMS-TC path function (see Annex L). The receiver shall always ensure INP_actn INP_minnaccording to the definition of INPpregardless of any vendor-discretionary techniques including, for example, the use of
36、erasure decoding. When the Reed-Solomon decoder in the receiver does not use erasure decoding, the INPpshall be computed as: symbolsDMT228_FECppppppppppNqRDSLqRDerasurenoINP= where parameters Dp, Rp, Lp, and qpare defined in clauses 9.4 and 9.5.4. When erasure decoding is used, INPpmight not equal I
37、NP_no_erasurep. Rec. ITU-T G.993.2 (2011)/Amd.2 (12/2012) 3 For single latency with ROC mode, the value INP_no_erasurepfor latency path #0 (the ROC) shall comply with: INP_no_erasure0 INPMIN-ROC (see clause 12.3.5.2.1.1) Within this equation, INPMIN-ROC is expressed in DMT symbols. The VTU-O shall c
38、alculate INPMIN-ROCus (in DMT symbols) from the CO-MIB value INPMIN-ROC-us (defined in clause 7.3.1.10.12 of ITU-T G.997.1 in multiples of T4k), and the VTU-R shall calculate INPMIN-ROCds (in DMT symbols) from the O-MSG 1 parameter INPMIN-ROC-ds value (defined in field #23 in multiples of T4k) as fo
39、llows: For 4.3125 kHz subcarrier spacing: INPMIN-ROC in DMT symbols = INPMIN-ROC in multiples of T4k. For 8.625 kHz subcarrier spacing: INPMIN-ROC in DMT symbols = 2 (INPMIN-ROC in multiples of T4k). with T4kas defined in clause 10.4.4. During initialization, the VTU-O, under direction from the CO-M
40、IB, can set a bit in initialization to require that the VTU-R receiver select framing parameters so that INPp= INP_no_erasurepon both latency paths. Regardless of whether this bit is set, the receiver shall always ensure INP_actn INP_minn. This bit is referred to as “INP_no_erasure_required“, bit 8
41、in the “Impulse noise protection“ field in Table 12-51, clause 12.3.5.2.1.1. During initialization, the VTU-R declares if it is using erasure decoding on either latency path. This field is referred to as “Erasure decoding used“ in Table 12-64, clause 12.3.5.2.2.3. Erasure decoding is vendor discreti
42、onary at both VTUs. 2.4) Clause 11.4.1.1.10 Change clause 11.4.1.1.10 as follows: 11.4.1.1.10 Actual impulse noise protection of the ROC (INP_act-ROC) The INP_act-ROC is the actual impulse noise protection of the ROC, as defined in clause 9.1, Figure 9-2. It shall be computed as INP_act-ROC = INP_no
43、_erasure0(see clause 9.6). The format shall be identical to that of the actual impulse noise protection INP_act of the bearer channels (see clause 11.4.1.1.9). The parameter INP_act-ROC is expressed in DMT symbols. The parameter ACTINP-ROC in the CO-MIB is expressed in multiples of T4k. The value is
44、 coded in fractions of T4kperiods with a granularity of 0.1 of a period. The range is from 0 to 25.4. At the Q-reference point, a special value indicates an ACTINP-ROC higher than 25.4. The T4kis defined in clause 10.4.4. The VTU-O shall calculate ACTINP-ROC as follows: For 4.3125 kHz subcarrier spa
45、cing: ACTINP-ROC = MIN( 10 INP_act-ROC / 10; 25.5). For 8.625 kHz subcarrier spacing: ACTINP-ROC = MIN( 5 INP_act-ROC / 10; 25.5). 4 Rec. ITU-T G.993.2 (2011)/Amd.2 (12/2012) 2.5) Clause 12.3.5.2.1.1 Change text for field #23 in clause 12.3.5.2.1.1 as follows: 12.3.5.2.1.1 O-MSG 1 Field #23 contains
46、 the value of INPMIN-ROCds expressed in multiples of T4Kas specified in the MIB. The value of INPMIN-ROCds expressed in DMT symbols (as to be used by the VTU-R receiver as specified in clause 9.6), is calculated as follows: For 4.3125 kHz subcarrier spacing: INPMIN-ROCds in DMT symbols = INPMIN-ROCd
47、s in multiples of T4k. For 8.625 kHz subcarrier spacing: INPMIN-ROCds in DMT symbols = 2 (INPMIN-ROCds in multiples of T4k). with T4kas defined in clause 10.4.4. The parameter INPMIN-ROCds (in DMT symbols) is defined as the required INP_no_erasure value for the ROC (see clause 9.6). INPMIN-ROC The v
48、alue of field #23 is an integer in the range from 0 to 8. If the CO does not support a robust overhead channel in the downstream direction, the fields #22 and #23 shall contain a value within the specified valid range for each of the parameters. These values shall be ignored at the receiver. 3) Accu
49、racy of test parameters 3.1) Clause 11.4.1.2 Change the following subclauses of clause 11.4.1.2 as indicated: 11.4.1.2 Accuracy of test parameters . 11.4.1.2.1 Accuracy of channel characteristics function per sub-carrier group (CCF-ps) 11.4.1.2.1.1 Accuracy of Hlog(k G f) Requirements for the Mean Absolute Error of the upstream Hlog(k G f) is for further study. 11.4.1.2.1.2 Accuracy of Hlin(k G f) The Hlin(k G f) reference values and Hlin(k G
