1、INTERNATIONAL TELECOMMUNICATION UNION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU G.116 (09/99) 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 performance objectives a p pl ica bl e to end -to-e n d i n te rn a t io n a I connections ITU-T Recommendation G. I 16 (Previously CCITT Recommendation) ITU-T RECOMMENDATION G.116 TRANSMISSION PERFORMANCE OBJECTIVES APPLICABLE TO END-TO-END INTERNATIONAL CO
3、NNECTIONS Summary This Recommendation is intended to provide guidance to network and service planners who are concerned with the performance of international connections, and to network element designers who are responsible for the equipment specification. Information relating to analogue, digital,
4、and analogue/digital terminal and network elements is provided. Additionally, this information is provided in the context of hybrid networks, i.e. networks built using analogue and digital network elements; integrated digital networks, i.e. networks with digital core network elements and analogue ac
5、cesses; and integrated services digital networks, i.e. networks which have only digital network, digital access and digital terminal elements. The transmission systems used to create these connections may operate as analogue or digital systems. Digital switches and transport systems may operate as A
6、TM, fiame relay, plesiochronous digital hierarchy (PDH), synchronous digital hierarchy (SDH), systems. The current regulatory operating environment in certain countries has made allowance for other networks to interconnect with the PSTN, e.g. private networks and digital cellular networks, and for c
7、ustomers to provision their own terminal equipment. The information in this Recommendation will provide guidance for all parties that wish to operate in this changing environment. Source ITU-T Recommendation G.116 was prepared by ITU-T Study Group 12 (1997-2000) and was approved under the WTSC Resol
8、ution No. 1 procedure on 30 September 1999. Recommendation G.116 (09/99) i STD-ITU-T RECMN G*LLbENGL 1777 llBb2571 ObbB083 Ullb FOREWORD ITU (International Telecommunication Union) is the United Nations Specialized Agency in the field of telecommunications. The ITU Telecommunication Standardization
9、Sector (ITU-T) is a permanent organ of the ITU. The 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 Conference (WTSC), whi
10、ch meets every four years, establishes the topics for study by the ITU-T Study 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. In some areas of informatio
11、n technology which fall within ITU-Ts purview, the necessary standards are prepared on a collaborative basis with IS0 and IEC. NOTE In this Recommendation the term recognized operating agency (ROA) includes any individual, company, corporation or governmental organization that operates a public corr
12、espondence service. The terms Administration, ROA and public correspondence are defrned in the Constitution of the ITU (Geneva, 1992). INTELLECTUAL PROPERTY RIGHTS The ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed I
13、ntellectual Property Right. The 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 approval of this Recommendation, the ITU ha
14、d not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementors are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database. O ITU 2000 All rig
15、hts reserved. No part of 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 Com the ITU. ii Recommendation G. 116 (09/99) 1 2 3 4 5 6 6.1 6.2 6.3 7 7.1 7.2 8 9 9.1 9.2 9.3 9.4 10 11
16、 12 13 13.1 13.2 13.3 14 15 15.1 15.2 CONTENTS Preamble., Introduction . Approach . Normative references . Attenuation (overall loudness rating) Attenuation distortion General Circuits Digital terminals . Clipping . Power level clipping . Temporal clipping Companders Echo General Circuits Digital te
17、rminals . Private networks Error on the reconstituted frequency Group delay . Linear crosstalk . Non-linear distortion Analogue non-linear distortion . Quantization distortion Distortion from low bit rate codecs Noise . Noise interference Single tone or narrow-band noise interference Wideband noise
18、interference 16 Variation of transmission loss with time . Recommendation G.116 (09199) Page 1 1 2 2 3 3 3 4 4 4 5 5 5 5 5 7 7 7 7 7 7 8 8 8 8 8 9 9 9 9 . 111 STD-ITU-T RECMN G-LLb-ENGL 1999 m q8b2591 Obb8085 717 m Recommendation G.116 TRANSMISSION PERFORMANCE OBJECTIVES APPLICABLE TO (Geneva, 1999)
19、 END-TO-END INTERNATIONAL CONNECTIONS 1 Preamble This Recommendation is intended to provide guidance to network and service planners who are concerned with the performance of international connections, and to network element designers who are responsible for the equipment specification. Information
20、relating to analogue, digital, and analogue/digital terminal and network elements is provided. Additionally, this information is provided in the context of hybrid networks, i.e. networks built using analogue and digital network elements; integrated digital networks, i.e. networks with digital core n
21、etwork elements and analogue accesses; and integrated services digital networks, i.e. networks which have only digital network, digital access and digital terminal elements. The transmission systems used to create these connections may operate as analogue or digital systems. Digital switches and tra
22、nsport systems may operate as ATM, fiame relay, plesiochronous digital hierarchy (PDH), synchronous digital hierarchy (SDH), systems. The current regulatory operating environment in certain countries has made allowance for other networks to interconnect with the PSTN, e.g. private networks and digit
23、al cellular networks, and for customers to provision their own terminal equipment. The information in this Recommendation will provide guidance for all parties that wish to operate in this changing environment. Digital technology has matured and it is recommended that all new switches, i.e. those us
24、ed for national and international switching, should be of digital design. Additionally, it is recommended that all new large private automatic branch exchanges (PBXs) should be digital and that interconnection with the PSTN should be digital, if practical, especially in those cases where the PBX per
25、forms a tandem fiinction. It is also recommended that all new international circuits be implemented on digital transmission systems, e.g. SDH. It is recognized that while it is desirable that national transmission systems should trend to digital operation, there may be a need to increment existing a
26、nalogue systems and guidance in this regard has been provided. It is also recognized that private networks may operate using PDWSDH, ATM, fiame relay, or other digital types of transport systems and may incorporate use of digital circuit multiplication equipment. Recommendation G.107 presents the E-
27、model, which is a computational model, that can be used for transmission planning. This Recommendation provides a model which can be used to determine the collective impact of impairments on overall connection performance. 2 Introduction Networks are in various stages of evolution towards being all-
28、digital. Thus, there will be instances where: connections will be routed utilizing all-digital components (end-to-end including the terminals); other connections will use all-digital network components and analogue access facilities; and still other connections will use portions of the network which
29、 are analogue while other network components may be digital. This Recommendation is intended to address each of these scenarios. Because the trend is towards digital, the masking benefits of significant channel noise for certain impairments found in analogue networks can no longer be assumed. As a r
30、esult, the guidance provided in this Recommendation will reflect this new environment. Recommendation G.116 (09/99) 1 3 Approach This Recommendation is intended to serve as the basis for all the transmission guidance available for end-to-end international connections. In this regard the hypothetical
31、 reference connections presented in Recommendation G.103 are used as a basis of this Recommendation. As digital technology continues to be implemented, the number of network connections over digital connections will increase while the number of connections over analogue systems will decrease. Thus,
32、this Recommendation will tend to focus on Connections similar to those shown in Figures UG.103, 2/G.103 and 31G.103. The end-to-end international connections can be considered to be comprised of two access facilities, two national extensions, and an international link composed of one or more interna
33、tional circuits. Additionally, this Recommendation makes the assumption that only digital exchanges and digital transport systems will be used in future international network segments. In the national extensions it is recognized that analogue elements will exist for years. 4 Normative references The
34、 following 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; all users of
35、this Recommendation 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. ITU-T Recommendation G. 1 O 1 (1 996), The transmissio
36、n plan. ITU-T Recommendation G. 103 (1 998), Hypothetical reference connections. ITU-T Recommendation G.107 (1998), The E-Model, a computational model for use in transmission planning. ITU-T Recommendation G. 1 13 (1 996), Transmission impairments. ITU-T Recommendation G. 1 14 (1 996), One-way trans
37、mission time. ITU-T Recommendation G. 120 (1 998), Transmission characteristics of national networks. ITU-T Recommendation G. 12 1 (1993), Loudness ratings (LRs) of national systems. ITU-T Recommendation G. 122 (1 993), Influence of national systems on stability and talker echo in international conn
38、ections. ITU-T Recommendation G. 126 (1993), Listener echo in telephone networks. ITU-T Recommendation G. 13 1 (1 996), Control of talker echo. ITU-T Recommendation G. 142 (1 998), Transmission characteristics of exchanges. ITU-T Recommendation G. 165 (1 993), Echo cancellers. ITU-T Recommendation G
39、. 168 (1 997), Digital network echo cancellers. ITU-T Recommendation G. 173 (1993), Transmission planning aspects of the speech service in digital public land mobile networks. ITU-T Recommendation G. 174 (1994), Transmission perjormance objectives for terrestrial digital wireless systems using porta
40、ble terminals to access the PSW. ITU-T Recommendation G. 175 (1997), Transmission planning for private/public network interconnection of voice traffic. ITU-T Recommendation G.176 (1997), Planning guidelines for the integration of ATM technology into networks supporting voiceband services. Recommenda
41、tion G.116 (09/99) ITU-T Recommendation G.711 (1988), Pulse code modulation (PCW of voice frequencies. ITU-T Recommendation G.722 (1988), 7 Idiz audio-coding within 64 kbith. ITU-T Recommendation G.723.1 (1996), Speech coders: Dual rate speech coder for multimedia communications transmitting at 5.3
42、and 6.3 kbith. ITU-T Recommendation G.726 (1 990), 40, 32, 24, 16 kbith adaptive differential pulse code modulation (ADPCIY). ITU-T Recommendation G.727 (1990), 5-, 4-, 3- and 2-bitshample embedded adaptive differential pulse code modulation (ADPCIY). ITU-T Recommendation G.728 (1992), Coding of spe
43、ech at 16 kbith using low-delay code excited linear prediction. ITU-T Recommendation G.729 (1996), Coding of speech at 8 kbith using Conjugate- Structure Algebraic- Code-Excited L inear-Prediction (CS-A CELP) . ITU-T Recommendation P. 1 1 (1993), Effect of transmission impairments. ITU-T Recommendat
44、ion P. 16 (1988), Subjective effects of direct crosstalk; thresholds of audibility and intelligibility. ITU-T Recommendation P.3 10 (1 996), Transmission characteristics for telephone band (300-3400 Hz) digital telephones. ITU-T Recommendation P.3 1 1 (1998), Transmission characteristics for wideban
45、d (I 50- 7000 Hz) digital handset telephones. ITU-T Recommendation P.340 (1 996), Transmission characteristics of hands-free telephones, ITU-T Recommendation P.34 1 (1 9929, Transmission characteristics for wideband (1 50-7000 Hz) digital hands-free telephony terminals. ITU-T Recommendation P.342 (1
46、 996), Transmission characteristics for telephone band (300-3400 Hz) digital loudspeaking and hands-free telephony terminals. Attenuation (overall loudness rating) The long-term objective for overall loudness rating is 8-12 dB. Additional guidance can be found in Recommendation P. 1 1. Apparatus ass
47、ociated with long-distance telephone circuits, e.g. network elements specified in the G. 160-series of Recommendations, should operate in compliance with Recommendations G. 1 O 1, G.121 and G.122. 6 Attenuation distortion 6.1 General The following Recommendations give guidance about attenuation dist
48、ortion for connections using specific operating arrangements: - - - - - Recommendation G. 120: for circuits; Recommendation P.3 1 O: for voiceband (300-3400 Hz) digital telephones; Recommendation P.3 1 1 : for wideband handset telephones; Recommendation P.340: for voiceband hands-ftee telephones; Re
49、commendation P.34 1 : for wideband hands-fiee telephones; and Recommendation G.116 (09199) 3 - Recommendation P.342: for voiceband digital loudspeaking and hands-fiee telephony In general, the intention of the ITU-T Recommendations for normal telephony, is to result in international connections, between electrical interfaces on an end-to-end concatenation of circuits1, whose effectively transmitted eequency band (i.e. the band in which the attenuation distortion does not exceed 9 dE3 compared with the value for 1020 Hz), will be a little wider than the 300-3400 Hz band. Although the ITU-T
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