1、COVERING NOTE GENERAL SECRETARIAT INTERNATIONAL TELECOMMUNICATION UNION Geneva, 3 1 January 2003 ITU -TELECOMMUNICATION STANDARDIZATION SECTOR Subject: Erratum 1 (01/2003) to ITU-T Recommendation G.996.1 (02/2001), Test procedures for digital subscriber line (DSL) transceivers Correction to Clause 7
2、.5 In the equation of clause 7.5 the sin term should be squared. The corrected equation is: X Union internationale des tlcommunications Place des Nations 121 1 GENVE 20 Suisse - Switzerland - Suiza INTERNATIONAL TELECOMMUNICATION UNION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU G.996.1 (0
3、2/2001) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS Digital sections and digital line system - Access networks Test procedures for digital subscriber line (DSL) transceivers ITU-T Recommendation G.996.1 (Formerly CCITT Recommendation) ITU-T G-SERIES RECOMMENDATIONS TRANSMI
4、SSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER- TRANSMISSION SYSTEMS INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES GENERAL CHARACTERISTICS OF INTER
5、NATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY TESTING EQUIPMENTS TRANSMISSION MEDIA CHARACTERISTICS DIGITAL TEWAL EQUIPMENTS DIGITAL NETWORKS DIGITAL SECTIONS AND DIGITAL LINE SYSTEM GfXl
6、eral Parameters for optical fibre cable systems Digital sections at hierarchical bit rates based on a bit rate of 2048 kbitk Digital line transmission systems on cable at non-hierarchical bit rates Digital line systems provided by FDM transmission bearers Digital line systems Digital section and dig
7、ital transmission systems for customer access to ISDN Optical fibre submarine cable systems Optical line systems for local and access networks G. 1 Offi. 199 G.20ffi.299 G.30ffi.399 G.40ffi.449 G.45ffi.499 G.50ffi.599 G.60ffi.699 G.70ffi.799 G.80ffi.899 G.90ffi.999 G.90ffi.909 G. 9 1 04.9 1 9 G.92ff
8、i.929 G.93 04.93 9 G.94ffi.949 G.95ffi.959 G.96ffi.969 G.97ffi.979 G.98ffi.989 Forjrther deaik, plme rejr to the list of ITU-TRecommendations. ITU-T Recommendation G.996.1 Test procedures for digital subscriber line SL) transceivers Summary This Recommendation describes the testing procedures for IT
9、U-T Digital Subscriber Line SL) Recommendations. The testing procedures described herein include methods for testing DSL transceivers in the presence of crosstalk fiom other services, Radio Frequency ingress, impulse noise and POTS signalling. Test loops and in-home wiring models are specified for d
10、ifferent regions of the world for use during DSL performance testing. Other DSL Recommendations reference this Recommendation for testing procedures and configurations. This Recommendation does not specie performance requirements for these other Recommendations; it only specifies the procedures for
11、measuring the performance requirements for a particular Recommendation. Source ITU-T Recommendation G.996.1 was revised by ITU-T Study Group 15 (2001-2004) and approved under the WTSA Resolution 1 procedure on 9 February 2001. ITU-T G.996.1(02/2001) 1 FOREWORD The International Telecommunication Uni
12、on (ITU) is the United Nations specialized agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tam questions and issuing Recommendations on them with a view to stan
13、dardizing 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 ITU-T Recommendations is c
14、overed 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 IS0 and IEC. NOTE In this Recommendation, the expression “Administration“ is used for conciseness to in
15、dicate both a telecommunication administration and a recognized operating agency. INTELLECTUAL, PROPERTY RIGHTS IT 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 concern
16、ing 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 notice of intellectual property, protected by patents,
17、 which may be required to implement this Recommendation However, implementors are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database. o ITU 2002 All rights reserved. No part of this publication may be reproduced or utilize
18、d in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing fkom ITU. ii ITU-T 6.996.1 (02/2001) CONTENTS Page 1 Scope 1 2 References . 3 Definit ions 4 Abbreviations 5 5.1 Test procedures and laboratory setup . DSL operation with spli
19、tters 5.1.1 Laboratory setup . 5.1.2 Crosstalk and RFI test . 5.1.3 Impulse noise test . 5.1.4 POTS interference test DSL operation without a splitter at the ATU-R 5.2.1 Laboratory setup . 5.2.2 Crosstalk and RFI test . 5.2.3 Impulse noise test . 5.2.4 POTS interference test 5.2 5.3 POTS QoS testing
20、 . 5.3.1 Telephone circuitry . 5.3.2 Test conditions . 5.3.3 Summary of test procedure . 6 Test loops.,. . 6.1 Local loop configurations European local test loops Test loops in an environment coexisting with TCM-ISDN DSL 6.1.1 6.1.2 6.1.3 North American test loops 6.2 In-home wlrmg models In-home wi
21、ring model #1 In-home wiring model #2: Daisy Chain 4-conductor, 24 AWG. non- paired station wire In-home wiring model #3: Star - 152.4 m (500 fi), 4-pair Category 3 wire . In-home wiring model for TCM-ISDN DSL environment . 6.2.1 6.2.2 6.2.3 6.2.4 7 7.1 7.2 7.3 Power spectral density of crosstalk di
22、sturbers Simulated DSL PSD and induced NEXT . Simulated HDSL PSD and induced NEXT Simulated Ti line PSD and induced NEXT 1 2 3 3 5 8 8 9 9 11 11 11 12 12 13 14 14 14 14 17 23 31 31 32 33 34 36 36 37 38 ITU-T G.996.1(02/2001) iii 7.4 7.5 7.6 7.7 7.8 7.9 8 9 9.1 9.2 9.3 Simulated G.992.1 downstream PS
23、D and induced NEXT and FEXT . 7.4.1 FEXT . 7.4.2 NEXT . Simulated G.992.1 upstream PSD and induced NEXT and FEXT 7.5.1 FEXT . 7.5.2 NEXT . Simulated G.992.2 downstream NEXT and FEXT . 7.6.1 FEXT . 7.6.2 NEXT . Simulated G.992.2 upstream NEXT and FEXT . 7.7.1 FEXT . 7.7.2 NEXT . ETSI A, ETSI B and Eu
24、ro-K crosstalk . Power spectral density of crosstalk disturbers in an environment coexisting with 7.9.1 Crosstalk disturber type 7.9.2 Crosstalk test parameters 7.9.3 Simulated TCM-ISDN DSL PSD and induced NEXT and FEXT 7.9.4 Simulated HDSL PSD and induced NEXT . 7.9.5 Simulated ADSL downstream PSD
25、and induced NEXT and FEXT . 7.9.6 Simulated ADSL upstream PSD and induced NEXT and FEXT . TCM-ISDN DSL . Characteristics of impulse noise waveforms Phone model structures or testing DSL systems without a splitter at the ATU-R Off-hook phone model #1 Off-hook phone model #2 On-hook phone model . Anne
26、x A . Primary constants of polyethylene-insulated cable (PIC) Page 40 40 41 42 43 43 44 44 45 46 46 47 48 50 50 51 52 55 57 60 62 70 70 71 72 75 iv ITU-T G.996.1(02/2001) ITU-T Recommendation G.996.1 Test procedures for digital subscriber line (DSL) transceivers 1 Scope This Recommendation describes
27、 the testing procedures for ITU-T DSL Recommendations. The testing procedures described in this Recommendation include methods for testing DSL transceivers in the presence of crosstalk fom other services, Radio Frequency ingress, impulse noise and POTS signalling. Test loops and in-home wiring model
28、s are specified for different regions of the world for use during DSL performance testing. Other DSL Recommendations reference this Recommendation for testing procedures and configurations. This Recommendation does not specie performance requirements for these other Recommendations. This Recommendat
29、ion only specifies the procedures for measuring the performance requirements for a particular Recommendation. An overview of Digital Subscriber Line (DSL) transceivers can be found in ITU-T G.995.1. 2 References The following ITU-T Recommendations and other references contain provisions which, throu
30、gh reference in this text, constitute provisions of this 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 t
31、he most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. - - ITU-T G.992.1 (1999), Asymmetric digital subscriber line (ALISL) transceivers. ITU-T G.992.2 (1 999), Splitterless asymmetric digital subsc
32、riber line (ADSL) transceivers. 3 Definitions This Recommendation defines the following terms: 3.1 downstream: ATU-C to ATU-R direction. 3.2 upstream: ATU-R to ATU-C direction. 3.3 splitter: A filter that separates the high fiequency signals (DSL) fiom the voiceband signals. 3.4 voiceband: The feque
33、ncy band fiom O to 4 kHz. 3.5 voiceband services: POTS and all data services that use the voiceband. 4 Abbreviations This Recommendation uses the following abbreviations: ADC Analogue-to-Digital Converter ADSL Asymmetric Digital Subscriber Line ATU-C ATU-R BER Bit Error Rate CO Central Ofice DAC Dig
34、ital-to-Analogue Converter ADSL Transceiver Unit, Central office end ADSL Transceiver Unit, Remote terminal end ITU-T G.996.1(02/2001) 1 DMT Discrete multitone DSL Digital Subscriber Line ES Errored Seconds FEXT Far-End crosstalk kbit/s kilobits per second NEXT Near-End crosstalk POTS Plain Old Tele
35、phone Service PSD Power Spectral Density QOS Quality of Service RF Radio Frequency RFI Radio Frequency Ingress RMS Root-Mean-Square RT Remote Terminal exclusive-or; modulo-2 addition xDSL XT Crosstalk xTU-C xTU-R Any of the various types of Digital Subscriber Lines (DSL) xDSL Transceiver Unit - Cent
36、ral office end xDSL Transceiver Unit - Remote Terminal end 5 The methods in this Recommendation test DSL system transmission performance. These laboratory methods evaluate a systems ability to minimize digital bit errors caused by interference fiom - - - background noise; - impulse noise; - POTS sig
37、nalling. These potential sources of impairment are simulated in a laboratory setup that includes test loops, test sets, and interference injection equipment, as well as the test system itself. The crosstalk and impulse noise interfering signals are simulations that are derived from a consideration o
38、f real loop conditions and measurements. The test procedure is to inject the interference into the test loops and measure the effect on system performance by a bit error test simultaneously run on the system information channels. For crosstalk an initial, or reference, power level for the interferen
39、ce represents the expected worst case. If the interference power can be increased without exceeding a specified error threshold, the system has a positive performance margin. Performance margin, expressed in dB, is the difference between the interference level at which the error threshold is reached
40、, and the reference (or O dB) level. In the case of impulse noise, an increasing interference level is similarly applied up to the error threshold, and the estimated performance is computed om this information. Because the impulse noise characteristics of the loop plant are not completely understood
41、, the estimation method is based on measured data fiom several sites. The estimated number of error-causing impulses is compared to a specified errored-seconds (ES) criterion. The test procedure makes separate determinations of Test procedures and laboratory setup crosstalk coupling fiom other syste
42、ms; differential and common mode Radio Frequency (RF) ingress 2 ITU-T G.996.1 (02/2001) crosstalk margins and impulse error thresholds, although a background crosstalk interference is applied during impulse tests. The POTS measurement uses a number of signalling and alerting activities done with rea
43、l phones and CO lines, and also has crosstalk interference present. The BER test sets check for ES or a BER thresh0 Id. 5.1 DSL operation with Splitters 5.1.1 Laboratory setup Figure 1 shows the test setup for measuring performance margins for the downstream channel in DSL systems with splitters. Fi
44、gure 2 shows the test setup for measuring performance margins for the upstream channel in DSL systems with splitters. The test setup permits differential and common mode signals to be superimposed on a working link, to simulate ingress situations. The test system consists of a central ofice transcei
45、ver (ATU-C), a remote end transceiver (ATU-R), and associated splitters. The two transceivers are connected together by the test loop. Crosstalk, impulses and Radio Frequency ingress (RFI) are injected at the ATU-R for downstream tests, and at the ATU-C for upstream channel tests. For downstream tes
46、ting, as shown in Figure 1 , pseudo-random binary data from the transmitter of the bit error rate (BER) test set is presented at the downstream channel input of the ATU-C. The downstream channel output from the ATU-R is connected to the receiver of the same or a similar BER test set. The test set me
47、asures BER or errored seconds (ES), as needed. Similar error testing is done in the upstream direction at the rate needed for the particular system under test (see Figure 2). A telephone set is connected to the telephone jack of the splitter at the ATU-R, and a working telephone line circuit is conn
48、ected to the telephone jack on the splitter at the AW-C. Figure UG.996.1- Laboratory test setup for measuring performance margins for the downstream channel with splitters ITU-T G.996.1(02/2001) 3 ,n UP- Channel Error Test - T, I 2 upstream ATU-R - Channel Error Test - ATU-C Splitter CO Line circuit
49、 attenuator f o 100 C.2 baiand 50 R unbalanced 50 R unbalanced 100 Q balanced POTS Set Hi-Z + I Simdated crosstalk 1 Noise I Q attenuator Simulated T1542170M) Figure 2/6.996.1- Laboratory test setup for measuring performance margins for the upstream channel with splitters The test set is essentially transparent in both directions between the transformers TI and Tz, so a normal working connection can be set up in the presence or absence of ingress. TI is a precision balun transformer. This minimizes the effects of any ingress that may be present. Note, however, that it will no
