1、 International Telecommunication Union ITU-T G.1029TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (02/2014) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS Multimedia Quality of Service and performance Generic and user-related aspects Voice service diagnosis framework Recomme
2、ndation ITU-T G.1029 ITU-T G-SERIES RECOMMENDATIONS TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS G.100G.199 GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS G.200G.299 INDIVIDUAL CHARACTERISTICS OF INTERNATIO
3、NAL 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 RADIOTELEPHONY AND LINE TELEPHONY G.450G.499 TRANSMISSION MEDIA AND OPTIC
4、AL 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 MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE GENERIC AND USER-RELATED ASPECTS G.1000G.1999TRANSMISSION MEDIA CHARACTERISTICS G.6000G.6999 DATA
5、 OVER TRANSPORT GENERIC ASPECTS G.7000G.7999 PACKET OVER TRANSPORT ASPECTS G.8000G.8999 ACCESS NETWORKS G.9000G.9999 For further details, please refer to the list of ITU-T Recommendations. Rec. ITU-T G.1029 (02/2014) i Recommendation ITU-T G.1029 Voice service diagnosis framework Summary Recommendat
6、ion ITU-T G.1029 provides a framework and guidelines that describe how ITU-T speech quality assessment models can be used to identify common voice quality problems in live networks and how these can aid in diagnosing the cause of such problems once detected. History Edition Recommendation Approval S
7、tudy Group Unique ID*1.0 ITU-T G.1029 2014-02-13 12 11.1002/1000/12121 Keywords Cause analysis, ITU-T objective model, problem diagnosis, voice service. _ *To access the Recommendation, type the URL http:/handle.itu.int/ in the address field of your web browser, followed by the Recommendations uniqu
8、e ID. For example, http:/handle.itu.int/11.1002/1000/11830-en. ii Rec. ITU-T G.1029 (02/2014) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunica
9、tion Standardization Sector (ITU-T) is a permanent organ of ITU. 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 basis. The World Telecommunication Standardization Assembly
10、(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 covered by the procedure laid down in WTSA Resolution 1. In some areas of information technology which fa
11、ll within ITU-Ts purview, the necessary standards are prepared on a collaborative 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 R
12、ecommendation is voluntary. However, the Recommendation may contain certain mandatory 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
13、 such as “must“ and the negative equivalents are used to express requirements. The 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 Reco
14、mmendation 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 of the date of ap
15、proval of this Recommendation, ITU had not received notice of intellectual property, protected 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 TS
16、B patent database at http:/www.itu.int/ITU-T/ipr/. ITU 2014 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. Rec. ITU-T G.1029 (02/2014) iii Table of Contents Page 1 Scope 1 2 References. 1 3 Definitions 2 3.1 T
17、erms defined elsewhere 2 3.2 Terms defined in this Recommendation . 2 4 Abbreviations and acronyms 2 5 Conventions 3 6 Framework concept and architecture 3 7 Introduction to speech quality measurement and assessment models 3 7.1 Subjective and objective testing . 3 7.2 Classes of objective models 5
18、7.3 Measurement configurations 7 8 Measurement data sources 8 8.1 Intrusive test probes 8 8.2 Non-intrusive test probes 8 8.3 Embedded probes . 8 8.4 Additional metrics 8 8.5 Multi-point measurements 9 8.6 Signalling related measurements 9 9 Decision process . 9 9.1 Thresholds 9 9.2 Analysing metric
19、s derived from live signals 9 9.3 Mapping basic diagnostic parameters into root cause analysis 10 Appendix I Example based on call clarity index 11 Bibliography. 13 Rec. ITU-T G.1029 (02/2014) 1 Recommendation ITU-T G.1029 Voice service diagnosis framework 1 Scope This Recommendation provides a fram
20、ework and guidelines that describe how ITU-T speech quality assessment models can be used to identify common voice quality problems in live networks and how these can aid in diagnosing the cause of such problems once detected. The scope of this Recommendation is limited to voice service only. The Re
21、commendation is intended to help non voice experts tasked with managing voice service and diagnosing voice quality problems, especially when voice is regarded as “just another IP application“ on the network. The scope of this Recommendation relates to the perceived quality of the media stream; it do
22、es not include factors such as billing, availability, customer service, etc. The primary focus is point-to-point voice services; however, the methods and approaches described can also be applied to the individual legs of multi-party voice applications such as audio-conferencing. 2 References The fol
23、lowing 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 Recommendations and other references are subject to revision; users of this Rec
24、ommendation 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 regularly published. The reference to a document within this Recommendation does no
25、t give it, as a stand-alone document, the status of a Recommendation. ITU-T P.561 Recommendation ITU-T P.561 (2002), In-service non-intrusive measurement device Voice service measurements. ITU-T P.562 Recommendation ITU-T P.562 (2004), Analysis and interpretation of INMD voice-service measurements.
26、ITU-T P.563 Recommendation ITU-T P.563 (2004), Single-ended method for objective speech quality assessment in narrow-band telephony applications. ITU-T P.564 Recommendation ITU-T P.564 (2007), Conformance testing for voice over IP transmission quality assessment models. ITU-T P.800 Recommendation IT
27、U-T P.800 (1996), Methods for subjective determination of transmission quality. ITU-T P.800.1 Recommendation ITU-T P.800.1 (2006), Mean Opinion Score (MOS) terminology. ITU-T P.800.2 Recommendation ITU-T P.800.2 (2013), Mean opinion score interpretation and reporting. ITU-T P.862 Recommendation ITU-
28、T P.862 (2001), Perceptual evaluation of speech quality (PESQ): An objective method for end-to-end speech quality assessment of narrow-band telephone networks and speech codecs. ITU-T P.862.1 Recommendation ITU-T P.862.1 (2003), Mapping function for transforming P.862 raw result scores to MOS-LQO. 2
29、 Rec. ITU-T G.1029 (02/2014) ITU-T P.862.2 Recommendation ITU-T P.862.2 (2007), Wideband extension to Recommendation P.862 for the assessment of wideband telephone networks and speech codecs. ITU-T P.863 Recommendation ITU-T P.863 (2011), Perceptual objective listening quality assessment. ITU-T Y.15
30、40 Recommendation ITU-T Y.1540 (2011), Internet protocol data communication service IP packet transfer and availability performance parameters. IETF RFC 3550 IETF RFC 3550 (2003), RTP: A Transport Protocol for Real-Time Applications. 3 Definitions 3.1 Terms defined elsewhere None. 3.2 Terms defined
31、in this Recommendation None. 4 Abbreviations and acronyms This Recommendation uses the following abbreviations and acronyms: CCI Call Clarity Index CQO Conversational Quality Objective ERL Echo Return Loss INMD In-line Non-intrusive Measurement Device IP Internet Protocol LQO Listening Quality Objec
32、tive LQONListening Quality Objective narrowband LQOWListening Quality Objective wideband LQOSWBListening Quality Objective super-wideband LQS Listening Quality Subjective MOS Mean Opinion Score PCM Pulse Code Modulation PLC Packet Loss Concealment PSTN Public Switched Telephone Network RMON Remote n
33、etwork Monitoring RTCP Real Time Control Protocol RTCP XR RTP Control Protocol extended Reports RTP Real time Transport Protocol SIP Session Initiation Protocol UDP User Datagram Protocol VOIP Voice Over IP Rec. ITU-T G.1029 (02/2014) 3 5 Conventions None. 6 Framework concept and architecture This R
34、ecommendation provides a set of high level guidelines. It provides an introduction to speech quality measurement and assessment models, measurement data sources and general considerations relating to defining decision thresholds and mapping diagnostic values to the root cause of voice service proble
35、ms. Appendix I is provided as an example and is used to illustrate some of the concepts described in this Recommendation. The ITU-T intends to provide two more Recommendations addressing, in detail, a framework for invoking diagnostic functions and a framework for mapping diagnostic parameters to ro
36、ot cause parameters, as follows: Framework for invoking diagnostic functions: Identification of decision parameters that can be used to detect the presence of a media quality problem in a network so that a diagnostic function can be invoked. Framework for mapping diagnostic parameters to root cause
37、parameters: This work item is concerned with mapping basic diagnostic parameters into root cause analysis parameters. Figure 1 shows the roadmap for the development of these two Recommendations. Figure 1 Roadmap for further development of framework Recommendations 7 Introduction to speech quality me
38、asurement and assessment models 7.1 Subjective and objective testing The perceived quality of a voice call is a subjective quantity. This means that the baseline for voice and audio quality is the subjective opinion of human listeners. One persons impression of “good“ may be quite different to anoth
39、er persons impression, but neither is incorrect. Communications systems are therefore designed and tested against an “average“ persons perception of voice quality. This is often summarized by the term mean opinion score (MOS). There are essentially two complementary approaches to measuring the quali
40、ty of a voice signal as it will be perceived by the end user. These are: 4 Rec. ITU-T G.1029 (02/2014) Subjective testing Objective testing These two approaches are described in the following clauses. 7.1.1 Subjective testing Subjective tests aim to find the average users perception of the voice qua
41、lity delivered by a communications system. This is done by asking a panel of users a directed question and providing them with a limited response choice. For example, to determine the listening quality of a voice signal, users are asked to rate “the quality of the speech“ on a five-point discrete sc
42、ale from bad to excellent as described in ITU-T P.800. The mean opinion score (MOS) for a particular test condition is calculated by averaging the votes of all subjects for that particular condition. A subjective test will typically contain many different conditions. Therefore, such tests take a lon
43、g time to perform and the results are influenced by a wide range of factors. 7.1.2 Objective testing Objective testing techniques measure physical properties of a system. Objective perceptual models map these physical properties to a predicted subjective score. In comparison with subjective testing,
44、 objective measurements are fast, inexpensive and repeatable. Significant work has led to objective prediction techniques that can be used in situations where it is impractical to perform formal subjective testing. 7.1.3 MOS notation Voice subjective experiments are generally designed to either meas
45、ure conversational quality or listening (one-way) quality. Conversational experiments investigate how effects such as delay, echo and level affect the ability of two people to carry out a conversation. Listening-only experiments are concerned with the perceived quality delivered by one side of a lin
46、k and take into account factors such as distortion due to voice compression and packet loss. This distinction is also true for objective speech quality models and they can be designed to predict either listening quality or conversational quality. The ITU-T has defined terms to denote the difference
47、between conversational and listening quality MOS values and the difference between MOS values from subjective experiments and MOS predictions made by objective models. The ITU-T notation defined in ITU-T P.800.1 is shown in Table 1. The suffixes N (narrowband), W (wideband) and SWB (super-wideband)1
48、are also sometimes added to the notation to denote whether the subjective experiment, or predicted experiment, was conducted in a narrowband (300-3 400 Hz), wideband (50-7 000 Hz) or super-wideband (50-14 000 Hz) context respectively. For example, listening quality assessed in a narrowband context s
49、ubjective experiment would be denoted as MOS-LQSN. The reader is also directed to ITU-T P.800.2, which introduces some of the more common types of mean opinion score (MOS) and describes the minimum information that should accompany MOS values to enable them to be correctly interpreted. _ 1The SWB suffix is not explicitly mentioned in ITU-T P.800.1, but the use of such extensions is encouraged where appropriate. Rec. ITU-T G.1029 (02/2014) 5 Table 1 ITU-T
