1、INTERNATIONAL TELECOMMUNICATION UNION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU G.103 (1 2/98) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS International telephone connections and circuits - General def i n it ions Hypothetical reference connections ITU-T Recomm
2、endation G. 103 (Previously CCITT Recommendations) COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling ServicesITU-T G-SERIES RECOMMENDATIONS TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS 11 INTERNATIONAL TELEPHONE CONNECTIONS AND CI
3、RCUITS G . I 00-G. 199 G.100-G.109 General Recommendations on the transmission quality for an entire international G. 1 1 O-G. I I9 telephone connection General characteristics of national systems forming part of international connections General Characteristics of the 4-wire chain formed by the int
4、ernational circuits and national extension circuits General characteristics of the 4-wire chain of international circuits; international transit circuits Transmission plan aspects of special circuits and connections using the international telephone connection network G. 120-G.129 G.130-G.139 G. 140
5、-G. 149 General characteristics of international telephone circuits and national extension Apparatus associated with long-distance telephone circuits G. 150-G. 159 G. 1 60-G. 1 69 G. 170-G.179 Protection and restoration of transmission systems Software tools for transmission systems G. 180-G.189 G.1
6、90-G.499 INTERNATIONAL ANALOGUE CARRIER SYSTEM TRAN SM ISS1 ON SYSTEMS SYSTEMS ON METALLIC LINES GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER- G ,200-G.299 INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE G.300-G.399 GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE S
7、YSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION G.400-G.449 WITH METALLIC LINES COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY G.450-G.499 TESTING EQUIPMENTS TRANSMISSION MEDIA CHARACTERISTICS DIGITAL TRANSMISSION SYSTEMS TERMINAL EQUIPMENTS DIGITAL NETWORKS DIGITAL SECTIONS AND DIGI
8、TAL LINE SYSTEM G.600-G.699 G.700-G.799 G.800-G.899 G. 900-G. 999 ForjfUrther details, please refer to ITU-T List of Recommendations. COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling Services- - STD-ITU-T RECMN G.103-ENGL 1996 m 4862571 Ob56231
9、T39 m ITU-T RECOMMENDATION G.103 HYPOTHETICAL REFERENCE CONNECTIONS Summary This Recommendation was revised to introduce Integrated Services Digital Network and Integrated Digital Network Hypothetical Reference Connections, and also to allow for the introduction of ATM Technology into the PSTN. This
10、 Recommendation provides a number of Hypothetical Reference Connections that can be used to perform transmission impairment studies. Source ITU-T Recommendation G.103 was revised by ITU-T Study Group 12 (1997-2000) and was approved under the WTSC Resolution No. 1 procedure on the 3d of December 1998
11、. Recommendation G.103 (12/98) 1 COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling ServicesSTDOITU-T RECMN G.LO3-ENGL 1998 YB62593 Ob56232 975 E FOREWORD ITU (International Telecommunication Union) is the United Nations Specialized Agency in the
12、field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of the ITU. The 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 ba
13、sis. The World Telecommunication Standardization Conference (WTSC), which meets every four years, establishes the topics for study by the ITU-T Study Groups which, in their turn, produce Recommendations on these topics. The approval of Recommendations by the Members of the ITU-T is covered by the pr
14、ocedure laid down in WTSC Resolution No. 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 term recognized operating agency (ROA) includes any individual, compan
15、y, corporation or governmental organization that operates a public correspondence service. The terms Administration, ROA and public correspondence are defined in the Constitution of the ITU (Geneva, I992). INTELLECTUAL PROPERTY RIGHTS The ITU draws attention to the possibility that the practice or i
16、mplementation of this Recommendation may involve the use of a claimed Intellectual Property Right. The 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
17、 process. As of the date of approval of this Recommendation, the ITU had not 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 therefor
18、e strongly urged to consult the TSB patent database. O ITU 1999 All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the ITU. II Recommendation G.
19、103 (12/98) COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling Services - - STD-ITU-T RECMN G-L3-ENGL 1998 m 4b259L Ob56233 BOL E CONTENTS Page 1 Scope 2 Purpose . 3 References 4 Composition of hypothetical reference connections L. . 5 Number of m
20、odulation and demodulation equipments 6 Developments arising from the ongoing introduction of PCM digital processes Annex A - An explanation of how hypothetical reference connections can be drawn assuming all send switching levels are O dBr . I 1 1 2 12 12 13 Recommendation G.103 (12/98) iii COPYRIG
21、HT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling ServicesSTD-ITU-T RECMN Ge103-ENGL 1998 I 48b2573i Ob56214 748 9 Recommendation G.103 HYPOTHETICAL REFERENCE CONNECTIONS (Mar del Plata, 1968; amended at Geneva, 1972, 1976 and 1980; at Malaga-Torremolin
22、os, 1984; revised in I998) 1 Scope This Recommendation provides a number of Hypothetical Reference Connections. In particular, connections involving hybrid, i.e. analoguedigital networks, and wholly digital networks are addressed. The ongoing transitional problems associated with the conversion of h
23、ybrid networks to wholly digital networks are addressed in clause 6. 2 Purpose A hypothetical reference connection for transmission impairment studies is a model in which the impairments contributed by circuits and exchanges are described. Such a model may be used by an Administration: - to examine
24、the effect on transmission quality of possible changes of routing structure, noise allocations, signal processing impairments and transmission losses in national networks; and to test national planning rules for prima facie compliance with any statistical impairment criteria which may be recommended
25、 by the ITU-T for national systems. For these purposes, several models are desirable. In each model, the international circuits and exchanges are assumed to be digital. The one wholly digital hypothetical reference connection and the five hybrid reference connections described below should encompass
26、 most of the studies required to be undertaken. - Hypothetical reference connections are not to be regarded as recommending particular values of loss or noise or other impairments, although the various values quoted are in many cases recommended values. Hypothetical reference connections are not int
27、ended to be used for the design of transmission systems. 3 References The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Re
28、commendations and other references are subject to revision; all users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is re
29、gularly published. 11 2 3 4 ITU-T Recommendation G. 1 1 1 (1 993), Loudness Ratings (LRs) in an international Transmission planning of switched telephone networks, ITU, Geneva, 1976. CCITT Recommendation E. 171 (1988), International telephone routingplan. ITU-T Recommendation G.lO1 (1996), The trans
30、mission plan. connection. Recommendation G.103 (12/9S) 1 COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling ServicesSTD.ITU-T RECMN Gm103-ENGL 1798 48b259L Ob5b2L5 b84 m ITU-T Recommendation G. 1 13 (1 996), Transmission impairments. ITU-T Recomme
31、ndation G. 1 14 (1 996), One-way transmission time. ITU-T Recornmendation G. 120 (1998), Transmission characteristics of national networks. ITU-T Recommendation G. 121 (1993), Loudness Ratings (LRs) of national systems. CCITT Recommendation G.726 (1990), 40, 32, 24, 16 kbit/s Adaptive Differential P
32、ulse Code Modulation (ADPCM). ITU-T Recommendation M.60 (1 993), Maintenance terminology and defznitions. ITU-T Recommendation P.3 1 O (1 996), Transmission characteristics for telephone-band (300 - 3400 Hz) digital telephones. Composition of hypothetical reference connections The composition of the
33、 various connections is defined in Figures 1,2,3,4,5 and 6. Figure I - The longest wholly digital Integrated Services Digital Network (ISDN) international connection with the maximum number of international and national circuits expected to occur in practice. Figure 2 - The longest Integrated Digita
34、l Network (IDN) international connection comprising the maximum number of international and national circuits expected to occur in practice. Figure 3 - An integrated digital network international connection comprising the maximum number of international circuits and the least number of national circ
35、uits expected to occur in practice. Figure 4 - An international connection comprising the maximum number of digital international circuits and the least number of analogue national circuits expected to occur in practice. Figure 5 - An international connection of moderate length (Le. not longer than
36、2000 km) comprising the most frequent number of international and analogue national circuits. In such a connection, the noise contribution of the national systems would be expected to predominate. Figuue 6 - The longest international connection with the maximum number of digital international and an
37、alogue national circuits expected to occur in practice. In such a connection, the noise contribution of the national systems would be expected to predominate. The attenuation distortion, group delay, and group-delay distortion would also be higher than for the IDN case. Such connections are expected
38、 to be extremely rare. 4.2 General remarks applicable to Figures I, 2, 3, 4, 5 and 6. 4.2.1 The hypothetical reference connections show the international circuits connected together at O dBr and O dBr virtual switching points, as they are digital switching points interconnected by digital facilities
39、, instead of -3.5 dBr and -4 dBr points, the values normally assigned to analogue ISC switches. This was felt to be more directly useful to those who might have to use the reference connections in their studies. It might be felt that it is somewhat inconsistent that the hypothetical reference connec
40、tions do not use “conventional“ analogue ISC -3 .Y-4 dBr virtual switching points. However, if the reference connections are drawn using that convention, the noise power figures appearing on the diagram can no longer be the familiar ones that appear elsewhere in other Recommendations. Annex A gives
41、further explanations. 4.2.2 The nomenclature is based on the international routing plan recommended in Recommendation E. 171 , i.e. ISC = International Switching Centre. 2 Recommendation G.103 (12/98) COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Hand
42、ling ServicesSTD-ITU-T RECMN G-LO3-ENGL 3998 4862593 Ob562Lb 510 D 4.2.3 In each case, only one direction of transmission is shown. 4.2.4 The design objectives for the mean noise powers are indicated according to current national recommendations. For long-distance national analogue carrier circuits
43、they are proportional to length, the appropriate noise power rate, 4 pWh or 1 pWh, being used according to whether the basic hypothetical reference circuit is one 2500 km long or 7500 km long. 4.2.5 The abbreviation pWOp stands for picowatts psophometric referred to a point of zero relative level. I
44、n the case of analogue exchange noise, the point referred to is considered to be in the circuit immediately downstream, of the exchange. The noise powers for circuits are referred to points of zero relative level in the circuits themselves and not to some point on the connection. 4.2.6 This Recommen
45、dation was prepared using the assumption that Plesiochronous Digital Hierarchy/Synchronous Digital Hierarchy (PDWSDH) technology and ATM digital technology may be used in the PSTN. 4.2.7 It is recommended that the E-Model be used to evaluate the transmission performance of specific configurations, e
46、specially when speech compression technology, e.g. G.726 compliant Digital Circuit Multiplication Equipment (DCME), is used. Recommendation G.103 (12/98) 3 COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling ServicesSTD-ITU-T RECMN G-103-ENGL 1998
47、48b2591 0656217 ir57 m -LE IIk 9 t+- T 9 t ISC k b 4-i ISC k b H ISC I I I ISC I ISC * I I LE I 4 4- 100 pwp (500 pWp) (Note 8) 4- O dB (T Pad) (Note 9) 4- O pWOp (Note 3) 4- O pWOp (Note 4) 4- O dB, o= O dB (Note 5) 4- O pWOp (Note 3) 4- O pWOp (Note 4) 4- O dB, o= O dB (Note 5) 4- O pWOp (Note 3)
48、f- O pWOp (Note 4) 4- O dB, o= O dB (Note 5) 4- O pWOp (Note 3) 4-. O pWOp (Note 4) 4-, O dB, o= O dB (Note 5) 4-. O pWOp (Note 3) 4- O pWOp (Note 4) 4- O dB, o= O dB (Note 5) e- O pWOp (Note 3) t- O pWOp (Note 4) t- t- e- - e- - O dB, o= O dB (Note 5) O pWOp (Note 3) O pWOp (Note 4) O dB, o= O dB (
49、Note 5) O pWOp (Note 3) O pWOp (Note 4) O pWOp (Note 3) 7 dB (R Pad) (Note 10) 3 dB at 1600 Hz. Root-f law for unloaded line plant 4- 100 pWp (500 pWp) (Note 8) see Note 16 for maximum value and length 5.5 dB, o= O or 3 dB, o= 1 (Note 17) 100 pWOp (200 pWOp) (Note 1 I) I * I I I I lscl 500 pWOp (2000 pWOp) (Note 18) 0.5 dB, o= 1; length 2500 km (Note 13) 4- O pWOp (Note 3) O pWOp (Note 4) O dl3, o= O dB (Note 5) O pWOp (Note 3) 500 pWOp (2000 pWOp) (Note 17) $ 40dB, o= 1 (Note 13) 100 pWOp (2000 pWOp) (Note i 1) Zero or 500 pWOp (Note 18)
