1、 International Telecommunication Union ITU-T G.993.2TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (12/2011) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS Digital sections and digital line system Access networks Very high speed digital subscriber line transceivers 2 (VDSL2)
2、 Recommendation ITU-T G.993.2 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 G.200G.299 INDIVIDUAL CHARACTERISTICS OF I
3、NTERNATIONAL 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 LINE TELEPHONY G.450G.499 TRANSMISSION MEDIA
4、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 hierarchical bit rates based on a bit rat
5、e 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 systems for customer access to ISDN G.960G.969
6、 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 CHARACTERISTICS G.6000G.6999 DATA OVER TRANSPORT GE
7、NERIC 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 (12/2011) i Recommendation ITU-T G.993.2 Very high speed digital subscriber line transceivers 2 (VDSL2) Summar
8、y Recommendation ITU-T G.993.2 specifies an access technology that exploits the existing infrastructure of copper wires that were originally deployed for POTS services. It can be deployed from central offices, from fibre-fed cabinets located near the customer premises, or within buildings. This Reco
9、mmendation is an enhancement to ITU-T G.993.1 that supports asymmetric and symmetric transmission at a bidirectional net data rate up to 200 Mbit/s on twisted pairs using a bandwidth up to 30 MHz. This version of this Recommendation integrates all of the previous amendments and corrigenda with the 2
10、006 version of Recommendation ITU-T G.993.2. 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) C
11、or. 2 2007-07-29 15 1.5 ITU-T 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 1.1
12、1 ITU-T G.993.2 (2006) Cor. 4 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 ii Rec. ITU-T G.993.2 (12/2011) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information
13、 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 view to standardizing telecommunications on a worldwide
14、 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 Recommendations is covered by the procedure laid down in WTSA R
15、esolution 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 administrat
16、ion 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 Recommendation is achieved when all of these mandatory provisions
17、 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. INTELLECTUAL PROPERTY RIGHTS ITU draws attention to the
18、 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, whether asserted by ITU members or others outside of
19、 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 cautioned that this may not represent the latest infor
20、mation and are therefore strongly urged to consult the TSB patent database at http:/www.itu.int/ITU-T/ipr/. ITU 2012 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.993.2 (12/2011) iii Table of Con
21、tents Page 1 Scope 1 2 References. 3 3 Definitions 4 4 Abbreviations and acronyms 8 5 Reference models 11 5.1 VTU functional model 11 5.2 User plane protocol reference model 13 5.3 Management plane reference model . 14 5.4 Application reference models . 15 6 Profiles 19 6.1 Definition 19 6.2 Profile
22、 parameter definitions 23 6.3 Profile compliance 26 7 Transmission medium interface characteristics 27 7.1 Duplexing method and band plan construction 27 7.2 Power spectral density (PSD) . 28 7.3 Termination impedance 44 7.4 Longitudinal conversion loss 44 8 Transport protocol specific transmission
23、convergence (TPS-TC) function . 45 8.1 The user data TPS-TC 45 8.2 Management TPS-TC (MPS-TC) . 47 8.3 Network timing reference TPS-TC (NTR-TC) 51 8.4 Time-of-day TPS-TC (ToD-TC) 52 9 Physical media specific transmission convergence (PMS-TC) sublayer . 59 9.1 PMS-TC functional model . 59 9.2 Scrambl
24、er 62 9.3 Forward error correction . 63 9.4 Interleaving . 63 9.5 Framing . 65 9.6 Impulse noise protection (INPp) . 75 9.7 Delay . 75 9.8 Bit error ratio (BER) . 76 9.9 Delay variation . 76 10 Physical media dependent (PMD) function 76 10.1 PMD functional model . 77 10.2 DMT superframe 77 10.3 Symb
25、ol encoder for data symbols 78 iv Rec. ITU-T G.993.2 (12/2011) Page 10.4 Modulation . 93 10.5 Symbol encoder for sync symbol . 97 10.6 Symbol encoder for initialization . 97 11 Operation and maintenance (OAM) . 98 11.1 OAM functional model . 98 11.2 VDSL2 management entity (VME) 100 11.3 OAM primiti
26、ves 129 11.4 OAM parameters 132 12 Link activation methods and procedures 164 12.1 Overview 164 12.2 Special operations channel (SOC) 172 12.3 Initialization procedure . 177 12.4 Loop diagnostic mode procedures 266 12.5 Fast start-up 275 13 On-line reconfiguration (OLR) . 275 13.1 Types of on-line r
27、econfiguration 275 13.2 Control parameters . 276 13.3 Timing of changes in subcarrier configuration 278 13.4 Receiver initiated procedure . 280 14 Electrical requirements . 284 14.1 Termination impedance model . 284 14.2 Service splitters 284 Annex A Region A (North America) 285 A.1 Band plan 285 A.
28、2 Limit PSD masks 285 A.3 UPBO reference PSDs 293 Annex B Region B (Europe) . 294 B.1 Band plans 294 B.2 Limit PSD mask options . 297 B.3 UPBO reference PSDs 311 B.4 Template PSD . 311 B.5 Compliance . 311 Annex C Region C (Japan) . 312 C.1 Band plan 312 C.2 Limit PSD masks 312 C.3 VDSL2 system with
29、 PSD reduction at frequencies below DPBOFMAX 321 C.4 Upstream power back-off (UPBO) PSD masks . 321 C.5 Service Splitter . 322 C.6 Test loops and crosstalk disturbers . 322 Rec. ITU-T G.993.2 (12/2011) v Page Annex D 324 Annex E 324 Annex F 324 Annex G 324 Annex H 324 Annex J 324 Annex K 324 Annex L
30、 TPS-TC functional descriptions . 325 L.1 STM transmission convergence (STM-TC) function . 325 L.2 ATM transmission convergence (ATM-TC) function . 331 L.3 Packet transmission convergence function (PTM-TC) 341 Annex M Time-of-day distribution over VDSL2 links 347 M.1 Time-of-day distribution operati
31、onal overview 347 M.2 Definitions 347 M.3 Abbreviations . 347 M.4 VTU functional model 347 M.5 TPS-TC function 347 M.6 eoc communication protocol 347 M.7 ToD TPS-TC (ToD-TC) . 347 M.8 Mapping of OH data . 347 M.9 eoc transmission protocol . 347 M.10 Frequency synchronization command 347 M.11 Time sy
32、nchronization command and responses . 349 M.12 Updates to initialization 349 Annex N ITU-T G.993.5-friendly ITU-T G.993.2 operation in the downstream direction 350 N.1 Power management commands and responses (clause 11.2.3.9) . 350 N.2 Initialization procedure (supplements clause 12.3) 351 Annex O F
33、ull ITU-T G.993.5-friendly ITU-T G.993.2 operation 358 O.1 Initialization procedure (supplements clause 12.3) 358 O.2 R-MSG1 (supplements clause 10.3.2.2 of ITU-T G.993.5) 359 O.3 O-TA_UPDATE (supplements clause 10.4.2.1 of ITU-T G.993.5) 360 O.4 R-P-VECTOR 2 (replaces clause 10.4.4.5 of ITU-T G.993
34、.5) . 360 O.5 O-PMS (supplements clause 10.5.2.1 of ITU-T G.993.5) . 360 O.6 eoc messages for backchannel configuration (replaces clause 8.1 of ITU-T G.993.5) 360 Appendix I Example values of DPBO parameters to protect ADSL2plus for clause C.3 361 I.1 Example PSD parameters . 361 I.2 Example Cable p
35、arameters . 361 I.3 Example frequency parameters 362 vi Rec. ITU-T G.993.2 (12/2011) Page Appendix II Impact of loop and VTU impedance mismatch on the Hlog accuracy . 363 Bibliography. 366 Rec. ITU-T G.993.2 (12/2011) 1 Recommendation ITU-T G.993.2 Very high speed digital subscriber line transceiver
36、s 2 (VDSL2) 1 Scope This Recommendation is an enhancement to ITU-T G.993.1 that supports transmission at a bidirectional net data rate (the sum of upstream and downstream rates) up to 200 Mbit/s on twisted pairs. This Recommendation is an access technology that exploits the existing infrastructure o
37、f copper wires that were originally deployed for POTS (plain old telephone service). This Recommendation specifies only discrete multi-tone (DMT) modulation and incorporates components from ITU-T G.993.1 (VDSL), ITU-T G.992.3 (ADSL2), and ITU-T G.992.5 (ADSL2 plus). Whilst POTS uses approximately th
38、e lowest 4 kHz and ADSL uses approximately 2 MHz of the copper wire spectrum, this Recommendation is defined to allow the use of up to 30 MHz of the spectrum. This Recommendation can be deployed from central offices, from fibre-fed cabinets located near the customer premises, or within buildings. Th
39、e availability of bandwidth up to 30 MHz allows ITU-T G.993.2 transceivers to provide reliable high data rate operation on short loops. Without the use of the US0 band, this Recommendation should operate reliably over loop lengths that are similar to those of ITU-T G.993.1, or slightly longer length
40、s due to the mandatory support of trellis coding. The addition of the US0 band and means to train echo cancellers and time-domain equalizers (TEQs) also allows this Recommendation to provide reliable operation on loops up to approximately 2 500 metres of 26 AWG (0.4 mm). This Recommendation defines
41、a wide range of settings for various parameters (such as bandwidth and transmitter power) that could potentially be supported by a transceiver. Therefore, this Recommendation specifies profiles to allow transceivers to support a subset of the allowed settings and still be compliant with the Recommen
42、dation. The specification of multiple profiles allows vendors to limit implementation complexity and develop implementations that target specific service requirements. Some profiles are better suited for asymmetric data rate services, whereas other profiles are better for symmetric data rate service
43、s. The annexes of this Recommendation include band plans and power spectral density (PSD) masks that address region-specific requirements. Like ITU-T G.993.1, this Recommendation defines upstream power back-off (UPBO) to mitigate far-end crosstalk (FEXT) caused by upstream transmissions on shorter l
44、oops to longer loops. The mechanism is the same as in ITU-T G.993.1. As do other ITU-T Recommendations in the G.99x series, this Recommendation uses ITU-T G.994.1 to initiate the transceiver training sequence. Changes in this Recommendation relative to ITU-T G.993.1 include: The definition of profil
45、es to support a wide range of deployment scenarios (e.g., central offices, fibre-fed cabinets located near the customer premises, and within buildings). For TPS-TC sublayer specifically, changes in this Recommendation relative to ITU-T G.993.1 include: Support for STM interfaces; Support for PTM int
46、erfaces based on IEEE 802.3 64/65 octet encapsulation; Support for ToD-TC functionality for transport of time-of-day over VDSL2 links. 2 Rec. ITU-T G.993.2 (12/2011) For PMS-TC sublayer specifically, changes in this Recommendation relative to ITU-T G.993.1 include: Improved framing (based on ITU-T G
47、.992.3); The definition of two latency paths and two bearer channels; Improved OLR mechanisms (based on ITU-T G.992.3), including optional SRA, SOS, and dynamic interleaver change; Control of delay variation; Improved overhead channel; Improved FEC capabilities, including a wider range of settings f
48、or the Reed-Solomon encoder and the interleaver; Improved interleaving with controlled memory-split between downstream and upstream; Support of all integer values of impulse noise protection (INP) up to 16 symbols; Optional impulse noise monitor function. For PMD sublayer specifically, changes in th
49、is Recommendation relative to ITU-T G.993.1 include: The definition, in annexes, of band plans up to 30 MHz to support a bidirectional net data rate up to 200 Mbit/s; Support for extension of the upper band edge of the US0 band to as high as 276 kHz (based on Annex M of ITU-T G.992.3); The definition of means to improve the performance of US0 (specifically, support in initialization for training of time dom
