1、 International Telecommunication Union ITU-T G.161.1TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (01/2014) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS International telephone connections and circuits Apparatus associated with long-distance telephone circuitsDo-no-harm t
2、esting Recommendation ITU-T G.161.1 ITU-T G-SERIES RECOMMENDATIONS TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS G.100G.199 Transmission planning and the E-model G.100G.109 General Recommendations on the transmission quality for an enti
3、re 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 extension circuits G.130G.139 General characteristics of the
4、 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.169Transmission plan aspects of special circuits and conn
5、ections 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-TRANSMISSION SYSTEMS G.200G.299 INDIVIDUAL CHARACTERISTICS O
6、F 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 RADIOTELEPHONY AND LINE TELEPHONY G.450G.499 TRANSMISSION MED
7、IA 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 MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE GENERIC AND USER-RELATED ASPECTS G.1000G.1999 TRANSMISSION MEDIA CHARACTERISTICS G.60
8、00G.6999 DATA 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.161.1 (01/2014) i Recommendation ITU-T G.161.1 Do-no-harm testing Summary Recommendat
9、ion ITU-T G.161.1 defines do-no-harm (DNH) tests for network-based and terminal-based voice quality enhancement (VQE) functions and non-VQE functions. Conventionally, performance specifications are written for telecommunication equipment to specify their performance characteristics in their intended
10、 application. Do-no-harm testing is a concept that has been introduced to specify tests which may be carried out to evaluate situations where the equipment, although meeting its performance specifications in its intended application, may cause some other unexpected performance degradation. Specific
11、DNH tests which relate to “fixed de-jitter buffer operation“ and “long-term media path delay stability“ are described in the annexes of this Recommendation. Where appropriate, these tests are backed up by case studies which are described in the appendices. It is anticipated that additional annexes c
12、overing other DNH scenarios will be added in the future. History Edition Recommendation Approval Study Group Unique ID*1.0 ITU-T G.161.1 2014-01-13 16 11.1002/1000/12053-en Keywords De-jitter buffer; delay stability; do no harm; media path delay; testing; voiceband data; 2100 Hz answering tone. _ *T
13、o access the Recommendation, type the URL http:/handle.itu.int/ in the address field of your web browser, followed by the Recommendations unique ID. For example, http:/handle.itu.int/11.1002/1000/11830-en. ii Rec. ITU-T G.161.1 (01/2014) FOREWORD The International Telecommunication Union (ITU) is th
14、e 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 responsible for studying technical, operating and tariff questions and issuing Rec
15、ommendations 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-T study groups which, in turn, produce Recommendations on these topics. Th
16、e 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 basis with ISO and IEC. NOTE In this Recommendation, the expression “Admin
17、istration“ 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 mandatory provisions (to ensure, e.g., interoperability or applicability) and co
18、mpliance 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 use of such words does not suggest that compliance with the Recommendatio
19、n 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 no position concerning the evidence, validity or applicability of claimed
20、 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 not received notice of intellectual property, protected by patents, which may be required to implement this Recommend
21、ation. 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 2014 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, wit
22、hout the prior written permission of ITU. Rec. ITU-T G.161.1 (01/2014) iii Table of Contents Page 1 Scope 1 2 References. 2 3 Definitions 2 3.1 Terms defined elsewhere 2 3.2 Terms defined in this Recommendation . 2 4 Abbreviations and acronyms 3 5 Conventions 3 6 General considerations for DNH testi
23、ng 3 7 Structure of do-no-harm tests . 4 7.1 Mandatory tests 4 7.2 Optional tests 4 7.3 Interoperability . 4 Annex A Fixed de-jitter buffer operation . 5 A.1 Introduction 5 A.2 Test purpose 5 A.3 Test method 5 A.4 Expected results 7 A.5 Requirements 8 Annex B Long-term media path delay stability 9 B
24、.1 Introduction 9 B.2 Test purpose 9 B.3 Test method 9 B.4 Expected results 10 B.5 Unacceptable delay variation on the end-to-end path 11 B.6 Requirements 12 Appendix I Case study relating to the performance of voiceband data applications over a Voice over Internet Protocol (VoIP) service . 13 I.1 B
25、ackground . 13 I.2 The problem 13 I.3 Test set-up 14 I.4 The cause of the problem . 16 I.5 Summary and conclusions 16 Bibliography. 17 Rec. ITU-T G.161.1 (01/2014) 1 Recommendation ITU-T G.161.1 Do-no-harm testing 1 Scope This Recommendation defines do-no-harm (DNH) tests for network-based and termi
26、nal-based voice quality enhancement (VQE) functions and non-VQE functions. These tests are applicable to functions used in both fixed and mobile networks and are independent of transport technology (e.g., TDM, ATM and IP). Where necessary, this Recommendation takes into account any similar tests tha
27、t already exist in other Recommendations (e.g., b-ITU-T G.160, b-ITU-T G.168 and b-ITU-T G.169) and is applicable to both stand-alone VQE and non-VQE functions and VQE and non-VQE functions connected in tandem. Where possible, the DNH tests defined in this Recommendation use standardized performance
28、 evaluation criteria (e.g., ITU-T P.862 and b-ITU-T P.863) and cover all possible in-band audio signals including speech, voiceband data and network signalling tones. Each test has a well-defined test configuration and a set of requirements that allow repeatability and consistency of results between
29、 different test laboratories. The following VQE and non-VQE functions are included in the scope for DNH: VQE functions: Echo cancellers including comfort noise injection Noise reduction/cancellation functions Automatic gain/level control Non-VQE functions: De-jitter buffers Codecs Voice activity det
30、ection Silence suppression Other functions which may be included are: Send or ingress (entering the network): Microphone array processing (MAP) High-frequency encoding (HFE) Equalization (EQ) Limiting (LM) Receive or egress (exiting the network): Bandwidth extension (BWE) Equalization (EQ) Noise com
31、pensation (NC; also referred to as ALE) Limiting (LM) This Recommendation provides guidance on how to conduct DNH testing, including case studies, as specific examples. 2 Rec. ITU-T G.161.1 (01/2014) 2 References The following ITU-T Recommendations and other references contain provisions which, thro
32、ugh 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 applying
33、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 P.50
34、1 Recommendation ITU-T P.501 (2012), Test signals for use in telephonometry. ITU-T P.862 Recommendation ITU-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 V.8 Recom
35、mendation ITU-T V.8 (2000), Procedures for starting sessions of data transmission over the public switched telephone network. ITU-T V.25 Recommendation ITU-T V.25 (1996), Automatic answering equipment and general procedures for automatic calling equipment on the general switched telephone network in
36、cluding procedures for disabling of echo control devices for both manually and automatically established calls. ETSI TS 102 929 ETSI TS 102 929 (V2.1.2) (2013-03), Speech and multimedia Transmission Quality (STQ); Procedures for the identification and selection of common modes of de-jitter buffers a
37、nd echo cancellers. 3 Definitions 3.1 Terms defined elsewhere This Recommendation uses the following terms defined elsewhere: 3.1.1 answering tone ITU-T V.25: The tone transmitted from the called end. NOTE 1 The answering tone is an uninterrupted 2100 15 Hz tone with a duration, except when truncate
38、d as described in clause 4.3 of ITU-T V.25, of 3.3 0.7 s. NOTE 2 Recommendation ITU-T V.8 specifies, for the purpose of starting sessions of data transmission, an amplitude modulated answering tone, ANSam. 3.1.2 de-jitter buffer b-ITU-T G.1020: A buffer designed to remove the delay variation (i.e.,
39、jitter) in packet arrival times. Data is put into the de-jitter buffer at a variable rate (i.e., whenever they are received from the network) and taken out at a constant rate. 3.1.3 phase reversals ITU-T V.25: Reversals (180) in the phase of the answering tone at intervals of 425 to 475 ms. The reve
40、rsal in phase shall be accomplished such that the phase is within 180 10 degrees in 1 ms, and that the amplitude of the answering tone is not more than 3 dB below its steady state value for more than 400 ms. 3.2 Terms defined in this Recommendation This Recommendation defines the following terms: 3.
41、2.1 do-no-harm (DNH): DNH is an attribute of a network-based or terminal-based function which states that if the function is included in the transmission path it does not degrade the performance of the media signal (e.g., speech or voiceband data) as measured using a stated metric. Note that dependi
42、ng on the metric, a tolerance may be necessary to allow some measureable degradation that is not significant for the user or application. For example, if the stated metric for voiceband data is the bit error rate (BER), then the requirement for DNH may be “zero increase in Rec. ITU-T G.161.1 (01/201
43、4) 3 BER when the specified function is enabled“. The stated metrics and their associated DNH tolerances for different media types are for further study. 4 Abbreviations and acronyms This Recommendation uses the following abbreviations and acronyms: ALE Automatic Listener Enhancement ANS Answering t
44、one ANSam Answering tone with amplitude modulation ATA Analogue Terminal Adapter ATM Asynchronous Transfer Mode BER Bit Error Rate BERT Bit Error Rate Tester BWE Bandwidth Extension DJB De-Jitter Buffer DNH Do No Harm EQ Equalization HFE High Frequency Encoding IP Internet Protocol LM Limiting MAP M
45、icrophone Array Processing MGW Media Gateway NC Noise Compensation PSTN Public Switched Telephone Network QoS Quality of Service RTP Real-time Transport Protocol SIP Session Initiation Protocol TDM Time Division Multiplex VoIP Voice over Internet Protocol VQE Voice Quality Enhancement 5 Conventions
46、None. 6 General considerations for DNH testing In general, do-no-harm (DNH) testing may be carried out on equipment at several different times in the product life-cycle, and this may require different test equipment and procedures, although for a given test the underlying test methodology should not
47、 change. 1) During product development in the laboratory, including integration of sub-modules into the final product: 4 Rec. ITU-T G.161.1 (01/2014) The main goal of DNH testing at this time is to evaluate certain DNH aspects of the performance of equipment, which should take into account anticipat
48、ed worst-case operational scenarios, and modify the design as necessary. Typically at this stage, some form of network simulator will be used to simulate the expected range of real-life operational parameters. 2) During field-trials, including integration with other equipment in the field, prior to
49、actual in-service operation: The main goal of DNH testing at this time is to confirm certain DNH aspects of the performance of the equipment in a real-world situation, particularly under practical performance conditions which are not always entirely under control, and when integrated with other equipment. 3) During in-service operation The main goal of DNH testing at this time is to diagnose the root cause of performance issue
