1、 ETSI TR 102 356 V1.1.1 (2004-04)Technical Report Speech Processing, Transmission and Quality Aspects (STQ);Application and enhancements of the E-Model (ETR 250);Overview of available documentation and ongoing workETSI ETSI TR 102 356 V1.1.1 (2004-04) 2 Reference DTR/STQ-00056 Keywords e-model, plan
2、ning, transmission ETSI 650 Route des Lucioles F-06921 Sophia Antipolis Cedex - FRANCE Tel.: +33 4 92 94 42 00 Fax: +33 4 93 65 47 16 Siret N 348 623 562 00017 - NAF 742 C Association but non lucratif enregistre la Sous-Prfecture de Grasse (06) N 7803/88 Important notice Individual copies of the pre
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7、fit of its Members. 3GPPTM is a Trade Mark of ETSI registered for the benefit of its Members and of the 3GPP Organizational Partners. ETSI ETSI TR 102 356 V1.1.1 (2004-04) 3 Contents Intellectual Property Rights4 Foreword.4 Introduction 4 1 Scope 5 2 References 5 3 Definition .5 4 Related documents
8、.6 5 Further improvement of the E-Model 9 History 12 ETSI ETSI TR 102 356 V1.1.1 (2004-04) 4 Intellectual Property Rights IPRs essential or potentially essential to the present document may have been declared to ETSI. The information pertaining to these essential IPRs, if any, is publicly available
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11、ay become, essential to the present document. Foreword This Technical Report (TR) has been produced by ETSI Technical Committee Speech Processing, Transmission and Quality Aspects (STQ). Introduction In 1996 ETSI launched with an unprecedented effort a unique transmission rating model which famously
12、 combined all available knowledge in the field of transmission planning. Under the leadership of Nils Olof Johannesson (1923-1997) a very concise document was elaborated by a special ETSI rapporteurs group and it was finally published as ETR 250 1. In the time thereafter this transmission rating mod
13、el was promoted to many other organization in the field, including the ITU-T, where Recommendation G.175 12 recommended for the first time in 1997, the use of the method described in ETR 250 1 for the transmission planning of Corporate and Enterprise Networks. After reconciliation and positive feedb
14、ack from users of ITU-T Recommendation G.175 12, the ITU-T, Study Group 12, in 1998 approved ITU-T Recommendation G.107 3 giving the principles and the algorithm of the now so-called “E-Model“ as the ITU-Ts unique and global transmission planning tool. Consequently, revisions and new recommendations
15、 with respect to the E-Model were launched and are currently being maintained. In appreciation of the tremendous success of the “E-Model“ in the ITU-T and based thereon in many other organizations, ETSI has never attempted, to parallelize this development by means of re-publishing documents from the
16、se organizations. The present document is intended to keep track of the development of the “E-Model“ outside ETSI. ETSI ETSI TR 102 356 V1.1.1 (2004-04) 5 1 Scope The present document provides an overview of the application and enhancements of the E-Model taking place in various standardization bodi
17、es; in addition it points to the most recent version of the E-Model. 2 References For the purposes of this Technical Report (TR), the following references apply: 1 ETSI ETR 250: “Transmission and Multiplexing (TM); Speech communication quality from mouth to ear for 3,1 kHz handset telephony across n
18、etworks“. 2 ETSI EG 201 050 (V1.2.2): “Speech Processing, Transmission and Quality Aspects (STQ); Overall Transmission Plan Aspects for Telephony in a Private Network“. 3 ITU-T Recommendation G.107 (2003): “The E-Model, a computational model for use in transmission planning“. 4 ITU-T Recommendation
19、G.108 (1999): “Application of the E-model: A planning guide“. 5 ITU-T Recommendation G.108.1 (2000): “Guidance for assessing conversational speech transmission quality effects not covered by the E-model“. 6 ITU-T Recommendation G.109 (1999): “Definition of categories of speech transmission quality“.
20、 7 ITU-T Recommendation G.113 (2001): “Transmission impairments due to speech processing“. 8 ITU-T Recommendation G.114 (2003): “One-way transmission time“. 9 ITU-T Recommendation G.131 (2003): “Talker echo and its control“. 10 TIA/EIA/TSB32-A (1998, reaffirmed 2002): “Overall Transmission Plan Aspe
21、cts for Telephony in a Private Network“. 11 TIA/EIA/TSB116 (2001): “Telecommunications - IP Telephony - Voice Quality Recommendations for IP Telephony“. 12 ITU-T Recommendation G.175: “Transmission planning for private/public network interconnection of voice traffic“. 13 ITU-T Recommendation P.562:
22、“Analysis and interpretation of INMD voice-services measurements“. 14 ITU-T Recommendation P.833: “Methodology for derivation of equipment impairment factors from subjective listening-only tests“. 3 Definition For the purposes of the present document, the following definition applies: E-Model: model
23、 based on the equipment impairment factor method, following previous transmission rating models NOTE 1: It was developed by an ETSI ad hoc group called “Voice Transmission Quality from Mouth to Ear“. ETSI ETSI TR 102 356 V1.1.1 (2004-04) 6 NOTE 2: The reference connection is split into a send side a
24、nd in a receive side. The model estimates the conversational quality from mouth to ear as perceived by the user at the receive side, both as listener and talker. According to the equipment impairment factor method, the fundamental principle of the E-model is based on a concept given in the descripti
25、on of the OPINE model (see Supplement 3 to ITU-T Series P Recommendations (1988), Models for predicting transmission quality from objective measurements.): square4 Psychological Factors on the psychological scale are additive. The result of any calculation with the E-model in a first step is a trans
26、mission rating factor R, which combines all transmission parameters relevant for the considered connection. This rating factor R is composed of: AeffIeIdIsRoR += , (1) Ro represents in principle the basic signal-to-noise ratio, including noise sources such as circuit noise and room noise. The factor
27、 Is is a combination of all impairments which occur more or less simultaneously with the voice signal. Factor Id represents the impairments caused by delay and the effective equipment impairment factor Ie,eff represents impairments caused by low bit rate codecs. It also includes impairment due to pa
28、cket-losses of random distribution. The advantage factor A allows for compensation of impairment factors when there are other advantages of access to the user. 4 Related documents ETR 250: “Transmission and Multiplexing (TM); Speech communication quality from mouth to ear for 3,1 kHz handset telepho
29、ny across networks“ 1. ETR 250 1 applies to mouth to ear narrowband (nominally 3,1 kHz) telephony connections via handsets across one or more telecommunications networks of any type, public or private, fixed or mobile. ETR 250 1 provides: a) a compendium of established and well recognized transmissi
30、on planning information on individual parameters, including limits for satisfactory performance and information on equipment with special transmission characteristics; b) a new simple computational planning method to consider the combination effect of transmission parameters when evaluating transmis
31、sion impairments for telephony services, including estimation of users opinion using the scales percentage poor or worse, percentage good or better, percentage terminating early and mean opinion score. The computational planning method is an adaptation of computation models published in ITU-T (forme
32、r CCITT) documentation, complemented with the result from some recently presented results of subjective tests. The objective is to assist network operators in ensuring that users will be satisfied with the transmission performance whilst avoiding over-engineering of the networks. The aim is to give
33、realistic, practical guidance rather than a scientifically exact treatment of quality factors. It should be noted that the computational planning method, which is described in clause 9, has not yet been fully verified and may give incorrect results. Until this verification has been completed, predic
34、tions resulting from the use of this planning method should therefore be treated with caution. ETSI ETSI TR 102 356 V1.1.1 (2004-04) 7 EG 201 050 (V1.2.2): “Speech Processing, Transmission and Quality Aspects (STQ); Overall Transmission Plan Aspects for Telephony in a Private Network“ 2. EG 201 050
35、2 represents a joint effort between TIA Subcommittee TR-41.1 (Multi-line Telecommunications Systems) and ETSI Technical Committee CN7 (Corporate Telecommunication Networks) (see note) to develop a global private network transmission planning guide. The intent of the document is to provide the planne
36、r of multi-national and transcontinental private networks with the transmission planning principles and planning examples which will enable the planner to design a loss and level plan for the network, optimized to the desired level of voice quality between any two users of the network as well as bet
37、ween the network and other - e.g. public networks. NOTE: The main effort on the part of ETSI in the development of EG 201 050 2 occurred during the existence of CN7. That working group was a successor to the transmission working group in ETSI working group BTC2. Working group CN7 has since closed do
38、wn and the work now continues as part of the program of ETSI Technical Committee STQ (Speech Processing, Transmission and Quality Aspects). The text of EG 201 050 2 was largely generated by ETSI as an update to an earlier ETSI Technical Report, ETR 004. Concurrent with that effort, TIA TR-41.1 start
39、ed a project to update the document “DPBX Loss Plan Application Guide“ (TSB-32-1989). TIA TR-41.1 and ETSI CN7 agreed in 1997 that there was a need for a common global transmission planning guide for private networks; therefore TIA TR-41.1 elected to work with the ETR 004 update project to generate
40、the present document by adding text (network characteristics, pertinent regional parameters, planning examples, and references) which would be of value to planners in both the North American and European regions. For North American users, the document is designated as the update of TSB-32-1989. Mean
41、while, ETSI published the document as ETSI Guide, EG 201 050 2. The underlying foundation for the planning guidelines in EG 201 050 2 is the ETSI E-Model for calculating and evaluating end-to-end connection voice quality. The E-Model is gaining universal acceptance as the tool for transmission plann
42、ing. It is expected that the E-Model will undergo refinements over time; the present document may require updating accordingly. As a component of the TSB-32-1989 update project, TIA TR-41.1 also undertook to examine a number of connection scenarios specific to North America for the illustration of l
43、oss design based on the E-Model. The rationale for this work was to provide continuity from the presentation in the initial publication of the TSB. Rather than including these scenarios in the document, it is intended to separately publish these scenarios as a companion document for demonstrating pr
44、actical applications of loss design for a variety of connection scenarios. ITU-T Recommendation G.107 (2003): “The E-Model, a computational model for use in transmission planning“ 3. ITU-T Recommendation G.107 3 gives the algorithm for the so-called E-model as the common ITU-T Transmission Rating Mo
45、del. This computational model can be useful to transmission planners, to help ensure that users will be satisfied with end-to-end transmission performance. The primary output of the model is a scalar rating of transmission quality. A major feature of this model is the use of transmission impairment
46、factors that reflect the effects of modern signal processing devices. In the year 2000 revision, an enhanced version of the E-model was provided, in order to better take into account the effects of room noise at the send side, and quantizing distortion. With the year 2002 revision, the impairment du
47、e to random packet-loss has been included in a parametric way for different codecs. The current version (2003) provides an enhanced modelling of the quality in case of low talker sidetone levels. ITU-T Recommendation G.108 (1999): “Application of the E-model: A planning guide“ 4. The intent of ITU-T
48、 Recommendation G.108 4 is to demonstrate how the E-Model (described in ITU-T Recommendation G.107 3) can be used in end-to-end transmission planning for a wide range of networks - local, national, multinational and transcontinental. ITU-T Recommendation G.108.1 (2000): “Guidance for assessing conve
49、rsational speech transmission quality effects not covered by the E-model“ 5. ITU-T Recommendation G.108.1 5 provides guidance for transmission planners on how to evaluate those effects impacting end-to-end speech transmission performance which are not covered by the E-model (ITU-T Recommendation G.107 3) and its associated Planning Guide (ITU-T Recommendation G.108 4). Procedures for informal subjective and objective evaluations that can be used to complement the E-model are provided here. ETSI ETSI
