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.998.4 TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (01/2015) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS Digital sections and digital line system Metallic access networks Improved impulse noi
2、se protection for digital subscriber line (DSL) transceivers Recommendation ITU-T G.998.4 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-TRA
3、NSMISSION 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 COORDINATION OF RADI
4、OTELEPHONY 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.910G.919 D
5、igital 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 and digital
6、 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-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.998.4 (01/2015) i Recommendation ITU-T G.998.4
8、 Improved impulse noise protection for digital subscriber line (DSL) transceivers Summary Recommendation ITU-T G.998.4 specifies techniques beyond those defined in the existing ITU-T digital subscriber line (DSL) Recommendations ITU-T G.992.3, ITU-T G.992.5 and ITU T G.993.2 to provide enhanced prot
9、ection against impulse noise or to increase the efficiency of providing impulse noise protection (INP). This version of this Recommendation integrates all of the previous amendments and corrigenda with the 2010 version of Recommendation ITU-T G.998.4. History Edition Recommendation Approval Study Gr
10、oup Unique ID* 1.0 ITU-T G.998.4 2010-06-11 15 11.1002/1000/10418 1.1 ITU-T G.998.4 (2010) Cor. 1 2010-11-29 15 11.1002/1000/11017 1.2 ITU-T G.998.4 (2010) Cor. 2 2011-04-13 15 11.1002/1000/11132 1.3 ITU-T G.998.4 (2010) Amd. 1 2011-06-22 15 11.1002/1000/11131 1.4 ITU-T G.998.4 (2010) Cor. 3 2011-12
11、-16 15 11.1002/1000/11399 1.5 ITU-T G.998.4 (2010) Amd. 2 2012-04-06 15 11.1002/1000/11505 1.6 ITU-T G.998.4 (2010) Cor. 4 2012-06-13 15 11.1002/1000/11646 1.7 ITU-T G.998.4 (2010) Cor. 5 2013-03-16 15 11.1002/1000/11894 1.8 ITU-T G.998.4 (2010) Amd. 3 2014-01-13 15 11.1002/1000/12092 1.9 ITU-T G.99
12、8.4 (2010) Amd. 4 2015-05-22 15 11.1002/1000/12377 2.0 ITU-T G.998.4 2015-01-13 15 11.1002/1000/12376 _ * To access the Recommendation, type the URL http:/handle.itu.int/ in the address field of your web browser, followed by the Recommendations unique ID. For example, http:/handle.itu.int/11.1002/10
13、00/11830-en. ii Rec. ITU-T G.998.4 (01/2015) FOREWORD The International 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 permanen
14、t 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 Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes
15、 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 areas of information technology which fall within ITU-Ts purview, the necessary standards
16、 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 operating agency. Compliance with this Recommendation is voluntary. However, the Recommen
17、dation 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 “shall“ or some other obligatory language such as “must“ and the negative equivalents are
18、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 possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intell
19、ectual 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 development process. As of the date of approval of this Recommendation, ITU had received no
20、tice 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 therefore strongly urged to consult the TSB patent database at http:/www.itu.int/ITU-T/ipr/. ITU
21、 2015 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.998.4 (01/2015) iii Table of Contents Page 1 Scope . 1 2 References . 1 3 Definitions 2 4 Abbreviations and acronyms 2 5 Overview . 3 6 Functio
22、nal reference model 4 7 TPS-TC function . 6 7.1 ATM TPS-TC . 6 7.2 PTM TPS-TC with 64/65-octet encapsulation . 8 8 Retransmission functions 9 8.1 DTU framer 9 8.2 Retransmission multiplexer 14 8.3 Transmitter retransmission state machine 14 8.4 Retransmission return channel (RRC) 14 8.5 Roundtrip 16
23、 8.6 Retransmission control parameters . 17 9 PMS-TC function 19 9.1 Scrambler 19 9.2 FEC . 19 9.3 Latency paths multiplexer 20 9.4 Framing parameters 20 9.5 Impulse noise protection . 25 10 PMD function . 26 10.1 Definition of MTBE . 26 10.2 General definition of signal-to-noise ratio margin . 27 1
24、0.3 Definition of MTBE_min . 27 10.4 Accelerated testing of MTBE . 27 11 Operation, administration and maintenance (OAM) management function 28 11.1 Configuration parameters . 28 11.2 Test parameters . 31 11.3 OAM line-related primitives 33 11.4 Performance monitoring parameters 34 11.5 Channel init
25、ialization policies 36 12 DTU counters 37 13 On-line reconfiguration (OLR) . 37 13.1 Bit swapping . 37 13.2 Seamless rate adaptation (SRA) . 37 iv Rec. ITU-T G.998.4 (01/2015) Page 13.3 SOS . 37 13.4 Transition mechanism for type 5 and type 6 modified OLR commands . 37 Annex A Support of ITU-T G.998
26、.4 with ITU-T G.992.3 . 39 A.1 Specific requirements . 39 A.2 Initialization 39 A.3 Management plane procedures . 48 A.4 OLR timing of changes in control parameters . 51 Annex B Support of ITU-T G.998.4 with ITU-T G.992.5 52 B.1 Specific requirements . 52 B.2 Initialization 52 B.3 Management plane p
27、rocedures . 53 B.4 OLR timing of changes in control parameters . 54 Annex C Support of ITU-T G.998.4 with ITU-T G.993.2 55 C.1 Specific requirements . 55 C.2 Initialization 58 C.3 Management plane procedures . 71 C.4 Timing of changes in control parameters . 76 Annex D Support of ITU-T G.998.4 with
28、ITU-T G.993.5 . 78 Annex E VDSL2 low power mode operation . 82 E.1 Scope 82 E.2 Functionality . 82 E.3 Link states and link state diagram 83 E.4 CO-MIB configuration and status reporting . 99 E.5 Coordination of link state transitions between VTU-O and VTU-R 102 E.5.7 L2.2-RX-Exit-Request command an
29、d responses . 108 Appendix I Transmit state machine 110 I.1 Reference transmit state machine . 110 I.2 Last chance retransmission state machine 111 Appendix II Motivation of MTBE accelerated test 112 Bibliography. 114 Rec. ITU-T G.998.4 (01/2015) 1 Recommendation ITU-T G.998.4 Improved impulse noise
30、 protection for digital subscriber line (DSL) transceivers 1 Scope This Recommendation specifies techniques beyond those defined in the existing ITU-T digital subscriber line (DSL) ITU-T G.992.3, ITU-T G.992.5 and ITU-T G.993.2 to provide enhanced protection against impulse noise or to increase the
31、efficiency of providing impulse noise protection (INP). Impulse noise is a noise event of limited duration that can degrade one or more transmitted symbols. Unlike the various types of continuous noise found on DSLs, impulse noise has a short duration and may repeat, either randomly or periodically.
32、 Impulse noise that does not appear to repeat periodically but occurs as unpredictable events is termed SHINE (single high impulse noise event). Impulse noise caused by noise from electrical mains and that thus repeats at a constant period related to the local AC power frequency is termed REIN (repe
33、titive electrical impulse noise). Impulse noise protection techniques are, in general, techniques used by a DSL transceiver to protect against the effects of impulse noise on the transmitted signal. Existing ITU-T DSL Recommendations specify techniques to ameliorate impulse noise effects. Among thes
34、e methods are the use of forward error correction (FEC) coding and interleaving. This Recommendation specifies a physical layer retransmission method for enhancing INP, with annexes specifically providing the details required for implementation of these techniques for transceivers supporting ITU-T G
35、.992.3, ITU-T G.992.5 and ITU-T G.993.2. Methods for enhancing INP by techniques other than physical layer retransmission are for further study. 2 References The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of th
36、is 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 edition of the Recommendations and othe
37、r 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.992.3 Recommendation ITU-T G.992.3 (2009), Asymmetric dig
38、ital subscriber line transceivers 2 (ADSL2). ITU-T G.992.5 Recommendation ITU-T G.992.5 (2009), Asymmetric digital subscriber line 2 transceivers (ADSL2) Extended bandwidth ADSL2 (ADSL2plus). ITU-T G.993.2 Recommendation ITU-T G.993.2 (2015), Very high speed digital subscriber line transceivers 2 (V
39、DSL2). ITU-T G.993.5 Recommendation ITU-T G.993.5 (2015), Self-FEXT cancellation (vectoring) for use with VDSL2 transceivers. 2 Rec. ITU-T G.998.4 (01/2015) 3 Definitions This Recommendation defines the following terms: 3.1 aggregate data rate (ADR): This is the sum of aggregate data rates per laten
40、cy over all latency paths and over the retransmission return channel (RRC). If retransmission is enabled, the aggregate data rate in the latency path #1 is the sum of the net data rate plus the overhead rate due to the data transfer unit (DTU) framer and the aggregate data rate in the latency path #
41、0 is the overhead rate. The aggregate data rate of the RRC is the rate excluding the overhead of the Golay code. The aggregate data rate is the rate at the A-reference point. 3.2 expected throughput (ETR): This is the rate available in Showtime at the /-reference point, assuming full protection agai
42、nst an impulse noise environment corresponding to the impulse noise environment as described by parameters in the MIB. 3.3 forward direction: This is the direction of transmission of the DTUs. 3.4 impulse noise protection (INP): This is the number of consecutive DMT symbols as seen at the -reference
43、 point, for which errors can be completely corrected by the retransmission function, regardless of the number of errors within the errored discrete multi-tone (DMT) symbols. 3.5 impulse protection against repetitive electrical impulse noise (INP_REIN): This is the number of consecutive DMT symbols t
44、hat are corrupted by REIN, as seen at the -reference point, for which errors can be completely corrected by the retransmission function, regardless of the number of errors within the errored DMT symbols. 3.6 line rate (LR): This is the data rate at the U-interface. 3.7 net data rate (NDR): This is t
45、he data rate at the /-reference point of the bearer channel mapped in latency path #1, assuming that no retransmissions occur. 3.8 overhead rate (OR): This is the rate assigned to the overhead channel carried in latency path #0. 3.9 repetitive electrical impulse noise (REIN): This is a type of elect
46、rical noise encountered on digital subscriber lines. It is evident as a continuous and periodic stream of short impulse noise events. Individual REIN impulses commonly have durations of less than 1 millisecond. REIN is commonly coupled from electrical power cable appliances drawing power from the AC
47、 electrical power network, having a repetition rate of twice the AC power frequency (100 or 120 Hz). 3.10 return direction: This is the direction of transmission of acknowledgements (in the RRC) of received DTUs. 3.11 single high impulse noise event (SHINE): This is a type of electrical noise encoun
48、tered on digital subscriber lines. SHINE generally arises as a periodic stream of impulses with effectively random inter-arrival time and impulse length both inversely related to intensity. Generally the term SHINE is associated with large impulses with durations in the range of milliseconds to seco
49、nds. 3.12 total data rate (TDR): This is the sum of total data rate per latency over all latency paths and the rate of the RRC including its forward error correction (FEC) overhead (Golay). This is the rate at the C-reference point. 4 Abbreviations and acronyms This Recommendation uses the following abbreviations and acronyms: ATM Asynchronous Transfer Mode ATTNDR Attainable Net Data Rate ATU-C Central office ADSL2/ADSL2plus Transceiver Unit Rec. ITU-T G.998.4 (01/2015)
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