ITU-T G 174-1994 Transmission Performance Objectives for Terrestrial Digital Wireless Systems Using Portable Terminals to Access the PSTN - General Characteristics of Internationalphon.pdf

1、INTERNATIONAL TELECOMMUNICATION UNION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU G.174 (06/94) GENERAL CHARACTERISTICS OF INTERNATIONAL TELEPHONE CONNECTIONS AND INTERNATIONAL TELEPHONE CIRCUITS TRANSMISSION PERFORMANCE OBJECTIVES FOR TERRESTRIAL DIGITAL WIRELESS SYSTEMS USING PORTABLE TE

2、RMINALS TO ACCESS THE PSTN ITU-T Recommendation G.174 (Previously “CCITT Recommendation“) ITU-T RECMN*G-L74 94 m 48b259L 0595b44 9b5 m FOREWORD The ITU-T (Telecommunication Standardization Sector) is a permanent organ of the International Telecommunication Union (IT). The ITU-T is responsible for st

3、udying technical, operating and tariff questions and issuing Recommen- dations 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 Stud

4、y Groups which, in their 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 (Helsinki, March 1-12, 1993). IT-T Recommendation G.174 was prepared by ITU-T Study Group 12 (1993-1996)

5、and was approved under the WTSC Resolution No. 1 procedure on the 21th of June 1994. NOTE In this Recommendation, the expression “Administration” is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. O ITU 1995 All rights reserved. No part of

6、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. ITU-T RECMN*G-L74 94 = 4Bb257L 0595645 8TL CONTENTS 1 Scope 2 Normative References 3 Abbreviations and Definitions .

7、 4 Reference Configuration PSTN Quality of Service Perspective . PSTN Transmission Performance Perspective . Transmission Effects of the Digital Radio Channel . Speech Transmission Performance Objectives 5 Overall PSTN Quality Perspective . 5.1 5.2 6 7 7.1 7.2 7.3 7.4 7.5 7.6 7.7 7.8 7.9 7.10 7.11 7

8、.12 7.13 7.14 General Loudness Ratings Weighted Terminal Coupling Loss . Delay and Echo Response Variations . Control of Echo from Outside the Wireless System . Idle Channel Noise . Noise Contrast and Comfort Noise . Random Bit Errors and Bursts of Errors Bandwidth . Stability Loss (Minimum Echo Pat

9、h Loss) . Quantization Distortion . Speech Coder Performance . Delay . Clipping (temporal) 8 Voiceband Data and Other Non-Speech Transmission 8.2 Application Requirements 8.3 Performance Suitability 8.4 Interworking . 8.6 Cali Progress Signals 8.1 General 8.5 DTMF . Page 1 1 2 2 3 3 4 4 5 5 6 6 7 7

10、8 8 9 9 10 10 10 10 10 10 10 11 11 11 12 12 Recommendation 6.174 (06/94) 1 ITU-T RECMN*G*L74 94 D 4862593 059564b 738 D SUMMARY This Recommendation provides transmission performance objectives that, if realized, should facilitate widespread user acceptance of emerging wireless technologies. These ob

11、jectives apply to terrestrial digital wireless systems that use portable terminals to access the PSTN. Additionally, this Recommendation reinforces the fact that “comparable PSTN quality” encompasses, among many other considerations, a broad set of transmission performance criteria, all of which nee

12、d to be considered to achieve the robustness and interworking capabilities of the PSTN. INTRODUCTION Next generation wireless personal communication systems, such as the Future Public Land Mobile Telecommunication System (FPLMTS) being standardized by the -R, are expected to be globally deployed by

13、the year 2000. A clearly stated objective of FPLMTS is to have its quality of service, which includes transmission performance, be comparable to that of the PSTN. It is widely recognized that this objective should be satisfied in order for these wireless access systems to achieve the general utility

14、 and wide acceptance that has been realized by the PSTN. Accordingly, this recommendation was developed with the goal of providing transmission performance objectives that should be met by a wireless system in order to be considered comparable to the PSTN. These objectives were derived to be generic

15、, and may or may not be directly applicable to FPLMTS, which may require other specific requirements. Because wireless personal communication systems can in effect replace the national extension part of an international connection, all the Recommendations dealing with the national extensions can als

16、o be applied to these wireless systems, unless this Recommendation gives other guidelines for planning the system. The objectives given here were derived in recognition of the fact that they should be specific enough to meaningfully guide sub-system development, yet flexible enough to accommodate th

17、e well-established need to tradeoff between quality and capacity in a variety of realistic radio operating environments. Finally, this Recommendation highlights the diversity of transmission performance criteria that need to be considered in order for the “comparable to PSTN” quality goal to be real

18、ized. 11 Recommendation G.174 (06/94) ITU-T RECMN*G=L74 94 D 4862591 0595b47 b74 Recommendation 6.174 TRANSMISSION PERFORMANCE OBJECTIVES FOR TERRESTRIAL DIGITAL WIRELESS SYSTEMS USING PORTABLE TERMINALS TO ACCESS THE PSTN (Geneva, 1994) 1 Scope This Recommendation provides transmission performance

19、objectives for terrestrial digital wireless systems that use portable terminals to access the PSTN (or the PSTN network interface).While satellite access to a base station is not within the scope of this Recommendation, interconnection with the PSTN, which may involve satellite access, or a satellit

20、e link within the PSTN, is not excluded. In this Recommendation, these portable terminals are generically referred to as wireless personal communication systems; however, there is no intent that the objectives herein necessarily apply to any specific wireless personal communication system. The objec

21、tives provided here have been derived with the explicit assumption that the switching and transmission systems used in the PSTN, above and including the local exchanges, are digital, with subscriber lines being either analogue or digital. This assumption allows for more pertinent guidance for the ti

22、me frame in which these future wireless systems are expected to be deployed. Such wireless systems are not expected to introduce, during stable operation, any significant transmission quality degradation relative to PSTN links covered by the G.100-Series of Recommendations. Currently, Recommendation

23、 G.173 exists for established mobile technologies that may not comply with this Recommendation for economic reasons. This Recommendation has two major purposes: first, to provide, in a single document, transmission performance objectives that, if realized, should facilitate widespread user acceptanc

24、e of emerging wireless technologies. The second major purpose of this Recommendation is to reinforce the fact that “comparable PSTN quality” encompasses, among many other considerations, a broad set of transmission Performance criteria, all of which need to be considered to achieve the robustness an

25、d interworking capabilities of the PSTN. 2 Normative References Recommendation E.430 Quality of Service Framework Recommendation E.800 Recommendation G. 1 13 Recommendation G. 1 14 Quality of Service and Dependability Vocabulary Transmission Impairments One-way Transmission Time Recommendation G.131

26、 Stability and Echo Recommendation G. 165 Echo Cancellers Recommendation G. 173 Transmission Planning Aspects of Speech Service in Digital Public Land Mobile Networks Recommendation G.7 11 Recommendation G.7 12 Recommendation G.726 Recommendation G.728 RecommendationP.3 1 Recommendation P.79 Recomme

27、ndation Q. 1001 Pulse Code Modulation (PCM) of Voice Frequencies Transmission Peiformance Characteristics of Pulse Code Modulation 40,32, 24, 16 kbit/s Adaptive Differential Pulse Code Modulation (ADPCM) Coding of Speech at 16 kbit/s Using Low Delay-Code Excited Linear Prediction Transmission Charac

28、teristics of Digital Telephone Sets Determination of Loudness Ratings General Aspects of Public Land Mobile Network Recommendation G.174 (O94) 1 ITU-T RECMN*G=L74 94 4862591 0595648 500 3 Abbreviations and Definitions For the purposes of this Recommendation, the following abbreviations apply: ADPCM

29、BER BLER DTMF EPL FFLMTS LD-CELP PCM PCS PLMN PSTN QDU RLR SLR TCL, Adaptive Differential Pulse Code Modulation Bit Error Ratio Block Error Ratio Dual Tone Multiple Frequency Echo Path Loss Future Public Land Mobile Telecommunication Systems Low Delay-Code Excited Linear Prediction Pulse Code Modula

30、tion Personal Communications Systems Public Land Mobile Network Public Switched Telephone Network Quantization Distortion Unit Receiving Loudness Rating Sending Loudness Rating Terminal Coupling Loss (weighted) Where possible, definition sources have been included in brackets : base station: The com

31、mon name for ail the radio equipment located at one and the same place used for serving one or several cells. See Recommendation Q.1001 .I handoff: The action of switching a call in progress from one cell to another (or between radio channels in the same cell), to allow established calls to continue

32、 when mobile stations move from one cell to another (or as a method to minimize Co-channel interference). See Recommendation Q. 100 1 . public land mobile network (PLMN): A network established and operated by an Administration or Recognized Operating Agency (ROA) for the specific purpose of providin

33、g land mobile telecommunication services to the public. A PLMN may be regarded as an extension of a fixed network (e.g. PSTN) or as an integral part of the PSTN. See Recommendation Q.100I.J PSTN: In this Recommendation, this term is intended to represent a fully digital path in the switched network,

34、 local exchange to local exchange, that is terminated at the far end (from the wireless access system) by either an analogue subscriber line and terminal or by a digital line and terminal. wireless access: Terminal access to the network using wireless technology. Examples are: digital mobile phones,

35、 digital cordless phones, and FPLMTS personal stations. wireline access: Terminal access to the network which uses wireline technology (e.g. conventional telephone sets and subscriber lines). wireless terminal: A general term used for any mobile station, personal station or personal terminal, with w

36、hich non- fixed access to the network is used. 4 Reference Configuration Figure 1 gives the general configuration of digital wireless personal access system to which the performance objectives of this Recommendation apply. When the network interface is digital, it should have a relative level of O d

37、Br in both directions of transmission. When an analogue line is used to interconnect the base station to the digital paths in the PSTN, other considerations apply (see for example Figure 4). 2 Recommendation G.174 (OtY94) ITU-T RECMN*G-174 94 = 4862571 0575647 447 Privacy coding Network Network inte

38、rface Interface I I I I Terrestrial radio Speech processing: Speech coding Speech interpolation Echo cancellation Analogue OT digital terminal RF Interface Wireless terminai (O dBr) Channel coding Example of pocsible base station cystern functions: TI 20740-94/dOI FIGURE VG.174 Reference configurati

39、on for wireless access systems 5 Overall PSTN Quality Perspective 5.1 PSTN Quality of Service Perspective Quality of Service is defined by ITU-T Recommendation E.800 as the collective effect of service performances which determine the satisfaction of a user of a service. Quality of service is charac

40、terized by the combined aspects of performance factors applicable to all services, such as: service support performance; service operability performance; service accessibility performance; service retainability performance; service integrity performance; and other factors specific to a given service

41、. Network performance is defined as the ability of a network or network portion to provide the functions related to communications between users; it contributes to service accessibility, service retainability and service integrity. Network performance parameter values are usually derived from qualit

42、y of service parameter values. ITU-T Recommendation E.430 gives a high-level 3 x 3 matrix as the prime structure for identifying all quality of service sources and relationships relevant to network performance. This high-level matrix, summarized below in Table 1, recommends using the criteria of spe

43、ed, accuracy and dependability to judge the quality with which the basic user functions of connection Set-up, user information transfer, and connection release are performed. Developers of wireless personal communication systems are advised to refer to Recommendation E.430 for the list of specific I

44、T-T Recommendations that apply to each cell of this matrix. Careful consideration of this framework of telecommunication service quality should facilitate user acceptance. Recommendation G.174 (06/94) 3 ITU-T RECflNUG.174 94 4862593 0595650 169 TABLE UG.174 High-level 3 x 3 matrix for quaiity of ser

45、vice User functions r -1 I I Connection Set-up User information transfer Connection release 5.2 PSTN Transmission Performance Perspective This subclause gives high-level requirements that should be satisfied by wireless personal communications systems, if such systems are to be part of an end-to-end

46、 connection with transmission performance similar (in terms of user expectations) to that of the PSTN. Following the general descriptions given in this subclause, more specific transmission performance objectives are given. If these performance objectives are met, then it is highly likely that a lev

47、el of performance would result that should satisfy the high-level requirements given now. Connections including the wireless system should, under error-free conditions, achieve subjective ratings comparable to those of connections in the ordinary PSTN. This is a necessary, but in no way sufficient,

48、condition for being considered “PSTN quality” or “toll quality.” To realize the widespread acceptance, from a quality perspective, of the PSTN, many other requirements should be satisfied by wireless systems. For example, the received speech should sound natural, and users should be able to recogniz

49、e the voices of people with whom they are familiar. In addition, wireless systems should be robust to transcodings (such as when used in tandem with a far-end wireless system); robust to a reasonable level of bit and frame errors; and robust to the wide variety of ambient noise conditions (e.g. offices, outdoors, motorways) under which such systems will be used. The list continues: highly interactive conversations should be possible with minor effort, meaning that excessive delays cannot be introduced; no annoying effects should be imposed on call progress tones, network a