1、GENERAL SECRETARIAT INTERNATIONAL TELECOMMUNICATION UNION Subject: Erratum Geneva. 7 December 2000 Recommendation ITU-T G.108 (09/99) TE LEC0 M M U N I CATI ON STANDARDIZATION SECTOR OF ITU ITU-T Recommendation G . 108 (09/99) Application of the E-model: A planning guide 1 . The following Table of F
2、igures and Table of Tables should be inserted under “Contents“ . TABLE OF FIGURES Figure UG.108 . Basic configuration for the interconnection between private and public network . Figure 2/G.108 . Standard configuration with a fully digital routing within the private network . Figure 3/G.108 . Privat
3、e Network with 4-wiren-wi1-e Conversion . Figure 4/G.108 . Digitally connected wireless telephone set Figure 5/G.108 . Basic connection between the PSTN and an IP network with its H.323 terminal and a PBX connected via an IWF . Figure 6/G.108 . The E-Model in the environment of subjective and object
4、ive testing Figure 7/G.108 . General configuration for calls via public networks Figure WG.108 . Example for the addition of impairments on a “Psychological scale“ . Figure 9/G . 108 . Relation between OLR and E-Model Rating R . Figure lO/G.108 . E-Model Rating R due to talker echo Figure 1 UG.108 .
5、 Relation between absolute delay (Ta) and E-Model Rating R . Figure 12/G.108 . Relation between the number of qdu and E-Model Rating R Figure 13/G.108 -Reference connection for the calculation of SLR and RLR . Figure 14/G.108 . Reference connection for echo calculations with one echo path . Figure 1
6、5/G . 108 . Reference connection for echo calculations with two echo paths Figure 16/G.108 . Details inside a cordless telephone with respect to echo control . Figure 17/G.108 . Basic reference configuration ofthe E-Model . Figure 1 WG.108 . Working configuration for 2-wire/2-wire connections Figure
7、 19/G.108 . Working configuration for 4-wire/2-wire connections Page 12 13 14 14 15 17 17 18 21 22 23 26 36 39 40 41 44 45 47 Union internationale des tlcommunications Place des Nations 121 1 GENVE 20 Suisse . Switzerland . Suiza COPYRIGHT International Telecommunications Union/ITU Telecommunication
8、sLicensed by Information Handling ServicesFigure 20/G.108 . Working configuration for 2-wire/4-wire connections Figure 2UG.108 . Working configuration for fully digital connections . Figure 22/G . 108 . Echo canceller Figure 23/G.108 . Application of a pair of echo cancellers within the private netw
9、ork Figure 24/G . 108 . Options for the location of an echo canceller Figure 25/G.108 . Use of echo cancellers in an internetwork or international connection . Figure 26/G.108 . Judgement of a connection on a linear quality scale Figure A.l/G.108 . Echo cancellers in a private network and their echo
10、 paths . Figure A.2/G.108 . Access and routing in public networks Figure A.3dG.108 . Configurations and transmission characteristics for the far-end termination . Europe . Figure A.3b/G.108 . Configurations and transmission characteristics for the far-end Termination . North America Figure B.UG.108
11、. Basic structure ofthe private network Figure B.2/G.108 . Reference configuration 1 Figure B.3/G.108 . Reference configuration 2 Figure B.4/G.108 . Reference configuration 3 Figure B.5/G. 108 . Use of low bit-rate equipment for a leased line Figure B.6/G.108 . Basis for calculation of reference con
12、figuration 1 . Figure B.7/G.108 . Basis for calculation of reference configuration 2 . Figure B.WG . 108 . Basis for calculation of reference configuration 3 . Figure B.9/G.108 . Application of echo control devices in the private network . Figure B . 1 O/G . 108 . Reference configuration 1 Figure B
13、. 1 1/G . 108 . Reference configuration 2 Figure B . 12/G . 108 . Reference configuration 3 Figure B . 13/G . 108 . Basis for calculation for reference configuration 1 a Figure B . 13dG . 108 . Analogue set A international transit General characteristics of international telephone circuits and natio
14、nal extension circuits Apparatus associated with long-distance telephone circuits Transmission plan aspects of special circuits and connections using the intemational telephone connection network Protection and restoration of transmission systems Software tools for transmission systems INTERNATIONAL
15、 ANALOGUE CARRIER SYSTEM TRANSMISSION SYSTEMS INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE WITH METALLIC LINES COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY TESTING EQUIPMENTS TRANSMISSION MEDIA
16、 CHARACTERISTICS DIGITAL TRANSMISSION SYSTEMS TERMINAL EQUIPMENTS DIGITAL NETWORKS DIGITAL SECTIONS AND DIGITAL LINE SYSTEM GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER- SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION G. 1 00-G. 199 G .I 0- .I O9 G.110-G.119 G.120-G. 129 G. 1
17、 30-G. 1 39 G. 140-G.149 G. 1504.159 G.160-G.169 G.170-G.179 G.180-G.189 G. 1 90-G. 199 G.20-G.299 G.300-G .399 G.400-G.449 G.45O-G.499 G .600-G .699 G .700-G .799 G.800-G.899 G .900-G .999 For furher details, please refer to ITU-T List of Recommendations. COPYRIGHT International Telecommunications
18、Union/ITU TelecommunicationsLicensed by Information Handling Services- STD.1TU-T RECflN Ge308-ENGL 3999 N 4862593 Obb9863 4T2 N ITU-T RECOMMENDATION Gel08 APPLICATION OF THE E-MODEL: A PLANNING GUIDE Summary The intent of this Recommendation is to demonstrate how the E-Model (described in Recommenda
19、tion G.107 3) can be used in end-to-end transmission planning for a wide range of networks - local, national, multinational and transcontinental. Source ITU-T Recommendation G.108 was prepared by IT-T Study Group 12 (1997-2000) and was approved under the WTSC Resolution No. 1 procedure on 30 Septemb
20、er 1999. Keywords E-Model, end-to-end, interconnection, Internet, network, PBX, planning, quality, speech, terminal, transmission. Recommendation G.108 (09/99) 1 COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling ServicesSTDmITU-T RECMN G-108-ENGL
21、 1997 W 11862591 Obb98b4 339 W FOREWORD ITU (International Telecommunication Union) is the United Nations Specialized Agency in the 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,
22、operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Conference (WTSC), which meets every four years, establishes the topics for study by the ITU-T Study Groups which, in t
23、heir turn, produce Recommendations on these topics. The approval of Recommendations by the Members of the ITU-T is covered by the procedure 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 collabor
24、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 The ITU draws attention to the possibility that the practice or imple
25、mentation 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 pro
26、cess. 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 therefore st
27、rongly urged to consult the TSB patent database. O ITU 2000 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. 11 Recommendation G.108
28、(09/99) COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling ServicesCONTENTS Page 1 Scope . 1 2 References . 2 3 Abbreviations 6 4 Definitions 4.1 Private network . 4.2 Public network 4.3 Quality aspects 4.4 IP based network . 9 10 4.5 Network elem
29、ents . 10 4.5.1 Terminal elements . 10 4.5.2 Connection elements 10 4.5.3 Transmission elements 11 4.6 Types of connections 11 5 Reference configurations 12 6 Basic planning principle . the impairment factor method in conjunction with the E-Model 7 Parameters subject to planning and their limits 20
30、7.1 Overall Loudness Rating . 20 7.2 Echo 7.3 Transmission time in echofree connections 7.3.1 General considerations . 7.3.2 Considerations with respect to low bit-rate coders 7.4 Stability . 7.5 Quantization distortion units . 7.6 Equipment impairment factor . 7.6.1 Equipment impairment factor for
31、codecs under conditions of packet loss 7.7 Delay variation versus time . 7.8 Advantage factor A . 7.9 Limits at the public/private interface with respect to echo . 7.9.1 Publidprivate network interfaces - Europe . 7.9.2 Public/private network interfaces - North America Parameters not directly subjec
32、t to transmission planning . 7.10.1 Frequency response 7.10.2 Circuit noise . 7.10.3 Listener echo 7.10 21 23 23 24 25 26 27 28 29 30 31 31 31 32 32 33 33 . Recommendation G.108 (09/99) 111 COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling Servic
33、es7.10.4 Sidetone . 7.10.5 Room noise 7.10.6 Comfort noise. voice activity detection . 7.10.7 Forward error correction 7.11 Synchronization 8 Calculation of end-to-end parameters . 8.1 Overall loudness rating . 8.2.1 Calculation for connections with one echo path 8.2.2 Calculation for connections wi
34、th two echo paths Transmission time in echofree connections 8.4 Quantization distortion units . 8.5 Equipment impairment factor . 8.2 Talker echo 8.3 8.6 8.7 Equipment impairment factor for codecs under conditions of packet loss . Delay variation versus time . 9 9.1 9.2 9.3 9.4 9.5 9.6 9.7 Applicati
35、on of the E-Model in planning practice . General Reference configurations Handling of the input parameters Interpretation of the results . Application of the E-Model for configurations with two echo paths . Use of computer programs Default values and parameter ranges 10 1 O . 1 10.2 10.3 10.4 10.5 R
36、ules for the insertion of echo cancellers . Introduction . Characteristics of the echo cancellers . Limits for the application of echo cancellers Determination of the location . Handling of echo cancellers in the E-Model . 11 Realization of planning . Determination of the specific requirements Defin
37、ition of the reference configurations End-to-end calculation with the E-Model . Analysis of the results . 11.1 General 11.2 1 1.3 11.4 1 1.5 1 1.6 Determination of the transmission parameters . Page 33 33 34 34 35 35 36 38 39 40 42 42 43 43 43 43 43 44 49 50 50 52 53 55 55 56 56 57 59 60 60 60 61 62
38、 62 63 iv Recommendation G.108 (09199) COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling Services - STDmITU-T RECMN GmLOB-ENGL 1997 11862591 Obb78b7 048 9 Annex A . Transmission parameters for specific elements . A . 1 A.2 A.3 Elements in private
39、 andor Il based networks A.l.l Wired telephone sets A . 1.2 Wireless telephone sets (including cordless) . A . 1.3 Switching equipment . Leased lines and tie trunks . A.1.4 IP gateways A . 1.5 A . 1.6 Privately owned cable links . A.1.7 Satellite links . A . 1.8 Low bit-rate coding A . 1.9 Packetize
40、d voice A . 1.10 Echo cancellers Transmission parameters of public networks . A.2.1 A.2.2 A.2.3 A.2.4 A.2.5 A.2.6 A.2.7 Loss Mean one-way delay Echo loss Insertion of echo cancellers . Quantization distortion units (qdu) Equipment impairment values (Ie) IP transmission related parameters Transmissio
41、n parameter of the far-end termination A.3.1 European far-end termination scenarios A.3.2 North American far-end termination scenarios . Annex B . Planning examples . B . 1 B.2 Planning example for the European scenario B . 1.1 Description of the network and users demand B.1.2 Definition of referenc
42、e configurations . B.1.3 B . 1.4 End-to-end calculation with the E-Model B . 1.5 Analysis of the results B . 1.6 Planning example or the North American scenario . B.2.1 Definition of reference configurations . B.2.2 Determination of the transmission parameters B.2.3 End-to-end calculation with the E
43、-Model B.2.4 Reference configuration la (analogue set A, analogue set B) B.2.5 Reference configuration lb (digital set A, analogue set B) B.2.6 Reference configuration 2 (portable connection scenario) Determination of the transmission parameters Application of echo cancellers . Recommendation G.108
44、(09199) Page 64 64 64 66 67 70 70 71 72 72 73 73 75 77 77 77 77 78 78 78 78 79 80 82 82 82 83 85 88 97 97 100 100 101 101 102 106 111 V COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling Services STDmITU-T RECMN G-LOB-ENGL 1999 m 4862593 0669868 T
45、84 m B.2.7 Reference configuration 3a (analogue set B) B.2.8 Planning example for IP transmission based scenarios Reference configuration 3b (digital set side B) . Annex C - Echo control in specific applications . Effective echo paths Echo path 1 : for talker at the cordless telephone . Echo path 2:
46、 for talker at the cordless telephone . Echo path 3: for talker at the cordless telephone . Echo path 4: for talker of the public network Echo path 5: for talker of the public network Echo path 6: for talker of the public network in an international call . B.3 C . 1 C . 1.1 C . 1.2 C . 1.3 C . 1.4 C
47、 . 1.5 (2.1.6 Operation of echo cancellers and soft suppressors . Provision of echo control for the talker of the public network . C.2 C.3 Page 116 120 125 127 127 127 127 127 128 128 128 129 130 vi Recommendation G.108 (09/99) COPYRIGHT International Telecommunications Union/ITU TelecommunicationsL
48、icensed by Information Handling ServicesIntroduction Network transmission planning has, historically, been based on scenarios reflecting the then-current (mainly analogue) technology, and the components (terminals, switches, facilities) available to the network. Today, the global telephone network t
49、ransmission environment is rapidly changing. Factors which are impacting this change are the no longer rigidly regulated network interconnections, liberalization of private network transmission parameters (particularly in Europe), increasing competition in the public networks, globalization of private networks, and the use of modern technology within private networks, driven by the customers need for economical and flexible network solutions. In North America, this traditional approach to planning had to take into account the industry- presc
