1、 International Telecommunication Union ITU-T G.113TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (11/2007) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS International telephone connections and circuits General Recommendations on the transmission quality for an entire intern
2、ational telephone connection Transmission impairments due to speech processing ITU-T Recommendation G.113 ITU-T G-SERIES RECOMMENDATIONS TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS G.100G.199 General definitions G.100G.109 General Rec
3、ommendations on the transmission quality for an entire international telephone connection G.110G.119 General characteristics of national systems forming part of international connections G.120G.129 General characteristics of the 4-wire chain formed by the international circuits and national extensio
4、n circuits G.130G.139 General characteristics of the 4-wire chain of international circuits; international transit G.140G.149 General characteristics of international telephone circuits and national extension circuits G.150G.159 Apparatus associated with long-distance telephone circuits G.160G.169 T
5、ransmission plan aspects of special circuits and connections using the international telephone connection network G.170G.179 Protection and restoration of transmission systems G.180G.189 Software tools for transmission systems G.190G.199 GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMI
6、SSION 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 RADIOTEL
7、EPHONY 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 QUALITY OF SERVICE AND PERFORMANCE GENERIC AND USER-RELATED ASPECTS G.1000G.19
8、99 TRANSMISSION MEDIA CHARACTERISTICS G.6000G.6999 DATA OVER TRANSPORT GENERIC ASPECTS G.7000G.7999 PACKET OVER TRANSPORT ASPECTS G.8000G.8999ACCESS NETWORKS G.9000G.9999 For further details, please refer to the list of ITU-T Recommendations. ITU-T Rec. G.113 (11/2007) i ITU-T Recommendation G.113 T
9、ransmission impairments due to speech processing Summary ITU-T Recommendation G.113 provides guidance regarding transmission impairments introduced by digital speech processing systems. The information provided is for use in conjunction with the transmission planning approach described in ITU-T Reco
10、mmendations G.107, G.108 and G.109. The impairment factor method, used by the E-model of ITU-T Recommendation G.107, is now recommended. The earlier method that used quantization distortion units is no longer recommended. Updated impairment factor values for various digital processing systems are pr
11、ovided in Appendix I. Appendix II contains guidance on how an advantage factor can be used to reflect the variation in user expectation of quality for different communications systems (e.g., mobile). Appendix III provides guidelines regarding individual transmission impairment parameters other than
12、qdu and equipment impairment factor, and Appendix IV gives provisional planning values for the wideband equipment impairment factor. Source ITU-T Recommendation G.113 was approved on 13 November 2007 by ITU-T Study Group 12 (2005-2008) under the ITU-T Recommendation A.8 procedure. ii ITU-T Rec. G.11
13、3 (11/2007) 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 permanent organ of ITU. ITU-T is responsi
14、ble 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 the ITU-
15、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 collaborative
16、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 Recommendation may contain certain mandat
17、ory 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 used to express requirements. The
18、use of such words does not suggest that compliance with the Recommendation is required of any party. INTELLECTUAL PROPERTY RIGHTS ITU 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
19、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 notice of intellectual property, pr
20、otected 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 2008 All rights reserved. No par
21、t of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. ITU-T Rec. G.113 (11/2007) iii CONTENTS Page 1 Scope 1 2 References. 1 3 Definitions 2 4 Abbreviations and acronyms 2 5 Conventions 2 6 Basic planning principle . 2 7 The impairment factor
22、method . 3 8 Equipment impairment factor, Ie 4 9 Quantization distortion unit (qdu) 4 Appendix I Provisional planning values for the equipment impairment factor, Ie, and packet-loss robustness factor, Bpl 7 Appendix II Considerations concerning the advantage factor A 11 II.1 Introduction 11 II.2 Com
23、ponents of user expectation 11 Appendix III Guidelines regarding individual transmission impairment parameters other than qdu and equipment impairment factor, Ie. 14 III.1 Attenuation distortion. 14 III.2 Group delay distortion 14 III.3 Talker echo . 14 III.4 One-way transmission time 14 III.5 Effec
24、t of random bit errors . 14 III.6 Effect of burst errors. 14 III.7 Effect of syllable speech clipping. 15 Appendix IV Provisional planning values for the wideband equipment impairment factor, Ie,wb 16 Bibliography. 18 ITU-T Rec. G.113 (11/2007) 1 ITU-T Recommendation G.113 Transmission impairments d
25、ue to speech processing 1 Scope This Recommendation provides guidance regarding transmission impairments introduced by digital speech processing systems. The information provided is for use in conjunction with the transmission planning approach described in ITU-T G.107, ITU-T G.108 and ITU-T G.109.
26、The impairment factor method, used by the E-model of ITU-T G.107, is now recommended. The earlier method that used quantization distortion units is no longer recommended. The E-model reflects the combined perceptual effects of different types of impairments on the end-to-end speech transmission perf
27、ormance by using impairment factors. Impairment factors represent the (degrading) contribution of one instrumentally measurable attribute of the connection (e.g., attenuation, loss), or of a complete piece of equipment (e.g., a low bit-rate coding and decoding process) on the overall quality as expe
28、rienced by the user. This degradation is called an “impairment factor“ in a general sense, and “equipment impairment factor“ when it is related to the degradations due to a specific piece of equipment. The E-model is highly useful because it combines the effects of different impairment factors. Netw
29、ork and service planners who are concerned with end-to-end speech transmission performance can use impairment factors with the E-model to assess the effects of introducing speech processing technologies. 2 References The following ITU-T Recommendations and other references contain provisions which,
30、through 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 apply
31、ing the most recent edition of the Recommendations and other 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
32、G.107 ITU-T Recommendation G.107 (2005), The E-model, a computational model for use in transmission planning. ITU-T G.108 ITU-T Recommendation G.108 (1999), Application of the E-model: A planning guide. ITU-T G.109 ITU-T Recommendation G.109 (1999), Definition of categories of speech transmission qu
33、ality. ITU-T G.168 ITU-T Recommendation G.168 (2007), Digital network echo cancellers. ITU-T G.711 ITU-T Recommendation G.711 (1988), Pulse code modulation (PCM) of voice frequencies. ITU-T G.712 ITU-T Recommendation G.712 (2001), Transmission performance characteristics of pulse code modulation cha
34、nnels. ITU-T O.132 ITU-T Recommendation O.132 (1988), Quantizing distortion measuring equipment using a sinusoidal test signal. ITU-T P.10 ITU-T Recommendation P.10/G.100 (2006), Vocabulary for performance and quality of service. 2 ITU-T Rec. G.113 (11/2007) ITU-T P.833 ITU-T Recommendation P.833 (2
35、001), Methodology for derivation of equipment impairment factors from subjective listening-only tests. ITU-T Q.551 ITU-T Recommendation Q.551 (2002), Transmission characteristics of digital exchanges. ITU-T Q.552 ITU-T Recommendation Q.552 (2001), Transmission characteristics at 2-wire analogue inte
36、rfaces of digital exchanges. ITU-T Q.553 ITU-T Recommendation Q.553 (2001), Transmission characteristics at 4-wire analogue interfaces of digital exchanges. ITU-T Q.554 ITU-T Recommendation Q.554 (1996), Transmission characteristics at digital interfaces of digital exchanges. ETSI ETR 250 ETSI ETR 2
37、50 (1996), Transmission and Multiplexing (TM); Speech communication quality from mouth to ear for 3,1 kHz handset telephony across networks. ETSI TR 102 356 ETSI TR 102 356 V1.1.1 (2004), Speech Processing, Transmission and Quality Aspects (STQ); Application and enhancements of the E-model (ETR 250)
38、; Overview of available documentation and ongoing work. 3 Definitions None. 4 Abbreviations and acronyms This Recommendation uses the following abbreviations and acronyms: GoB Good or Better MOS Mean Opinion Score PoW Poor or Worse qdu Quantization distortion unit 5 Conventions None. 6 Basic plannin
39、g principle The rapidly changing scenario in the field of multiple interconnected networks with increasing size and complexity in combination with new technologies and the constraint for more economical solutions requires more flexibility with respect to transmission planning. In general, the qualit
40、y of speech transmission via telephone channels is based on a subjective judgment by the users at both ends. Therefore, traditionally, transmission was in principle derived from an end-to-end consideration in conjunction with a partitioning of all relevant parameters between different networks or pa
41、rts of a network. As networks become more complex (e.g., the proliferation of digital mobile access networks and networks that transport voice calls as packets) this approach is no longer applicable. Accordingly, the recommended planning approach is to use the impairment factor method (see clause 8)
42、 in conjunction with the E-model (see ITU-T G.107). ITU-T Rec. G.113 (11/2007) 3 A fundamental purpose of network planning is to control the summation of transmission impairments caused by the different network elements in all possible configurations. It is not the task of network planning to limit
43、the transmission impairment of a specific network element. Unless indicated otherwise, it is assumed that transmission, switching and terminal elements in general are designed to meet all relevant requirements as given in ITU-T Recommendations and in international or national standards applicable fo
44、r this type of element. In auditory tests using human subjects estimates of the integral quality, thus covering different quality dimensions, are often expressed in terms of MOS, %GoB or %PoW. During transmission planning, however, it is not practical to perform subjective tests. Therefore, a method
45、 must be provided which enables the planner to combine by calculation all existing transmission impairments in the given connection to a total value of impairment. This calculation must be performed by using an algorithm based on subjective testing. In telephone connections consisting of a variety o
46、f network elements, different transmission parameters may also simultaneously contribute to the total impairment. Therefore, the planning method used must also incorporate combination effects. For all configurations, the planning of speech transmission quality should be based on an end-to-end consid
47、eration rather than on a specification of individual objective parameter limits. For the calculation of the different impairment values, particularly if the combined effect from the presence of more than one parameter needs to be considered, computational models are used for planning purposes. Sever
48、al such “rating-models“ have been developed and were contained and described in former ITU-T publications, which are no longer recommended for application and which today have bibliographic status only. Today, ITU-T G.107 gives the algorithm for the so-called E-model as the common ITU-T transmission
49、 rating model. Transmission planning based on the E-model as recommended provides a prediction of the expected quality as perceived by the user for an investigated connection. Based on an end-to-end assessment for each transmission parameter (including the type and number of low bit-rate codecs) impairment values are derived. This model accounts for low bit-rate coding devices as well as for impairments introduced by standard PCM coders and for impairments not directly related t
