1、INTERNATIONAL TELECOMMUNICATION UNION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU G.992.1 Corrigendum 2 (0712002) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS Digital sections and digital line system - Access networks Asymmetric digital subscriber line (ADSL) tran
2、sceivers Corrigendum 2 ITU-T Recommendation G.992.1 (1 999) - Corrigendum 2 ITU-T G-SERIES RECOMMENDATIONS TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS TRANSMISSION SYSTEMS INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE
3、SYSTEMS ON METALLIC LINES GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER- GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY TESTING EQUIPMENTS TRANSMIS
4、SION MEDIA CHARACTERISTICS DIGITAL TERMINAL, EQUIPMENTS DIGITAL NETWORKS DIGITAL SECTIONS AND DIGITAL LINE SYSTEM General Parameters for optical fibre cable systems Digital sections at hierarchical bit rates based on a bit rate of 20 8 kbit/s Digital line transmission systems on cable at non-hierarc
5、hical bit rates Digital line systems provided by FDM transmission bearers Digital line systems Digital section and digital transmission systems for customer access to ISDN Optical fibre submarine cable systems G. 1 00-G. 199 G.200-G.299 G.300-G.399 G.400-G.449 G.450-G.499 G.50M.599 G.60W.699 G.700-G
6、.799 G.800-G.899 G.900-G.999 G.900-G.909 G.910-G.9 19 G.920-G.929 G.930-G.939 G.940-G.949 G.950-G.959 G.960-G.969 G.970-G.979 Optical line systems for local and access networks G.980-G.989 Access netw$rks G.99o-G.999 QUALITY OF SERVI AND PERFORMANCE G. 160-G.1999 TRANSMISSION MEDIA CHARACTERISTICS G
7、.6000-G.6999 DIGITAL TERMINAL EQUIPMENTS G.7000-G.7999 DIGITAL NETWORKS G.8000-G.8999 ForJUrther details, please refer to the list of ITU-T Recommendations. ITU-T Recommendation G.992.1 Asymmetric digital subscriber line (ADSL) transceivers Corrigendum 2 Summary This corrigendum addresses interopera
8、bility issues identified with the operation of ADSL in the TCM-ISDN environment as defined in Annex C. The corrigendum clarifies two things to improve interoperability : - the definition of the dummy bit insertion for the fast data using single latency path - the PRD sequence generator in single bit
9、map operation. The corrigendum also corrects an editorial mistake on Figure C.20, which should be replaced with Figure C.17 of ITU-T Rec. G.992.2. Source Corrigendum 2 to ITU-T Recommendation G.992.1 (1 999) was prepared by ITU-T Study Group 15 (200 1-2004) and approved under the WTSA Resolution 1 p
10、rocedure on 29 July 2002. ITU-T Rec. G.992.1(1999)/Cor.2 (07/2002) 1 FOREWORD The International Telecommunication Union (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 re
11、sponsible 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 the topics for study by th
12、e 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 are prepared on a collabor
13、ative basis with IS0 and IEC. NOTE In this Recommendation, the expression “Administration“ is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. INTELLECTUAL, PROPERTY RIGHTS IT draws attention to the possibility that the practice or implement
14、ation 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 the Recommendation development process. As
15、 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, implementors are cautioned that this may not represent the latest information and are therefore strongly urged to
16、consult the TSB patent database. o ITU 2002 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. 11 ITU-T Rec. G.992.1(1999)/Cor.2 (07/2002) ITU-T Recommendation G.992.1 Asymmetric digital subscriber line (ADSL) tra
17、nsceivers Corrigendum 2 The following changes should be made to Annex C: 1) Clause C.4.4.2 Replace the last paragraph (and mathematical expression) as follows: If the fast data buffer uses single latency only, &e additional dummy bits are inserted at the tail of each FEXT symbol in the 4 Bitmap-FR c
18、onstructed subframe. The number of the additional dummy bits inserted at the tail of each FEXT symbol shall be as follows: dmYSRf = fR - fRf4 The receiver shall determine Bitmap-FR and Bitmap-NR so that dummyRj is less than 126, dummyf4 is less than 4 and dummyRp is less than 3 in the initialization
19、 sequence. At the receiver, the inserted dummy bits shall be removed. 2) Clause C.5.2.2 Replace the last paragraph (and mathematical expression) as follows: If the fast data buffer uses single latency only, additional dummy bits are inserted at the tail of each FEXT symbol in the 4 Bitmap-Fc constru
20、cted subframe. The number of the additional dummy bits inserted at the tail of each FEXT symbol shall be as follows: . - ic 2n -348 JG 14- JCFJvl 1 dWYSCf = fcf3 - fCf4 “C 1 “ The receiver shall determine Bitmap-Fc and Bitmap-Nc so that dummyci is less than 126, dummycp is less than 4 and dummycp is
21、 less than 3 in the initialization sequence. At the receiver, the inserted dummy bits shall be removed. 3) Clause C.7.6.2 Add the following Note: NOTE - At the transmitter, the PRD sequence generator is either always updated or always stopped during NEXTR symbol when Bitmap-NR is disabled (FEXT Bitm
22、ap mode). The receiver should be able to support both modes of transmitter operation. 4) Clause C.7.8.3 Add the following Note: NOTE - At the transmitter, the PRD sequence generator is either always updated or always stopped during NEXTR symbol when Bitmap-NR is disabled (FEXT Bitmap mode). The rece
23、iver should be able to support both modes of transmitter operation. 5) Figure C.20 Replace Figure C.20 with Figure C. I7 of ITU-T Rec. G.992.2. ITU-T Rec. G.992.1(1999)/Cor.2 (07/2002) 1 SERIES OF ITU-T RECOMMENDATIONS Series A Series B Series C Series D Series E Series F Series G Series H Series I
24、Series J Series K Series L Series M Series N Series O Series P Series Q Series R Series S Series T Series U Series V Series X Series Y Series Z Organization of the work of ITU-T Means of expression: definitions, symbols, classification General telecommunication statistics General tariE principles Ov
25、erall network operation, telephone service, service operation and human factors Non-telephone telecommunication services Transmission systems and media, digital systems and networks Audiovisual and multimedia systems Integrated services digital network Cable networks and transmission of television,
26、sound programme and other multimedia signals Protection against interference Construction, installation and protection of cables and other elements of outside plant TMN and network maintenance: international transmission systems, telephone circuits, telegraphy, facsimile and leased circuits Maintena
27、nce: international sound programme and television transmission circuits Specifications of measuring equipment Telephone transmission quality, telephone installations, local line networks Switching and signalling Telegraph transmission Telegraph services terminal equipment Terminals for telematic services Telegraph switching Data communication over the telephone network Data networks and open system communications Global information infrastructure and Internet protocol aspects Languages and general software aspects for telecommunication systems Printed in Switzerland Geneva, 2002
