1、 STDmITU-T RECMN E.450-ENGL It978 m 4862591 Ob470bY YTO w INTERNATIONAL TELECOMMUNICATION UN ION ITU=T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU E.450 (O 3/98) SERIES E: OVERALL NETWORK OPERATION, TELEPHONE SERVICE, SERVICE OPERATION AND HUMAN FACTORS Quality of service, network management and
2、 traffic engineering - Network management - Checking the quality of the international telephone service Facsimile quality of service on public networks - General aspects ITU-T Recommendation E.450 (Previously CCIlT Recommendation) ITU-T E-SERIES RECOMMENDATIONS OVERALL NETWORK OPERATION, TELEPHONE S
3、ERVICE, SERVICE OPERATION AND HUMAN FACTORS )PERA TION, NUMBERING, ROUTING AND MOBILE SERVICES NTERNATIONAL OPERATION OPERATIONAL PROVISIONS RELATING TO CHARGING AND ACCOUNTING IN THE I“AT1ONAL TELEPHONE SERVICE UTILIZATION OF THE INTERNATIONAL TELEPHONE NETWORK FOR NON- TELEPHONY APPLICATIONS ISDN
4、PROVISIONS CONCERNING USERS ZUALITY OF SERVICE, NETWORK UANAGEMENT AND TRAFFIC ENGINEERING NETWORK MANAGEMENT International service statistics International network management Checking the quality of the international telephone service TRAFFIC ENGINEERING Measurement and recording of traffic Forecas
5、ting of traffic Determination of the number of circuits in manual operation Determination of the number of circuits in automatic and semi-automatic operation Grade of service Definitions ISDN traffic engineering Mobile network traffic engineering QUALITY OF TELECOMMUNICATIC SERVICES : CONCEPTS, OBJE
6、CTIVES AND DEPENDABILITY PLANNING ODELS, E.330-E.399 E.400-E.409 E.410-E.4 19 E.420-E.489 E.490-ES05 E.506-ES09 E.510-ES19 E.520-ES39 E.540-ES99 E.600-E.699 E.700-E.749 E.750-E.799 For further details, please refer to ITU-T List ofRecommendations. STD-ITU-T RECMN E-450-ENGL 3778 4862573 0b470bb 273
7、W ITU-T RECOMMENDATION E.450 FACSIMILE QUALITY OF SERVICE ON PUBLIC NETWORKS - GENERAL ASPECTS Summary Facsimile is the most important non-voice application on international PSTN and the most widely used standard is group 3 facsimile. This Recommendation is aimed at forming a framework for Recommend
8、ations on facsimile qualiy of service on PSTN. A roadmap of the E.450-series Recommendations is shown in Figure 1. Source ITU-T Recommendation E.450 was revised by ITU-T Study Group 2 (1997-2000) and was approved under the WTSC Resolution No. 1 procedure on the 9th of March 1998. Recommendation E.45
9、0 (03/98) 1 STD-ITU-T RECNN E.450-ENGL 1998 4Bb2591 0647067 LOT FOREWORD ITU (international Telecommunication Union) is the United Nations Specialized Agency in the field of telecommuni- cations. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of the ITU. The IT-T is re
10、sponsible 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), which meets every four years, establishes the topics for study by
11、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 information technology which fall within ITU-Ts purview, the necessary st
12、andards are prepared on a collaborative basis with IS0 and IEC. NOTE In this Recommendation, the expression “Administration” is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. INTELLECTUAL PROPERTY RIGHTS The ITU draws attention to the poss
13、ibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual 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
14、the Recommendation development process. As of the date of approval of this Recommendation, the ITU had 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 lates
15、t information and are therefore strongly urged to consult the TSB patent database. O ITU 1998 All tights 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 from
16、 the ITU. 11 Recommendation E.450 (03198) - STD-ITU-T RECMN E.450-ENGL 1778 4862591 0647068 046 CONTENTS Page 1 Scope 1 2 Introduction 1 3 Connection establishment and disconnection . 2 2 3.1 Start dial signal delay and post dialling delay 3.2 Facsimile phase A completion rate . 2 4 Message transmis
17、sion . 2 Annex A - Glossary of terms and abbreviations for E.450-Series Recommendations . 3 Recommendation E.450 (03/98) . 111 STD-ITU-T RECMN E.450-ENGL 1998 4862571 Ob47069 T82 Recommendation E.450 FACSIMILE QUALITY OF SERVICE ON PUBLIC NETWORKS - GENERAL ASPECTS (Helsinki, 1993; revised in 1998)
18、1 Scope Facsimile is the most important non-voice application on international PSTN and the most widely used standard is group 3 facsimile. This Recommendation is aimed at forming a framework for Recommendations on facsimile quality of service on PSTN. A roadmap of the E.450-Series Recommendations i
19、s shown in Figure 1. I E.451 I cut-Offs t E.452 Speed E453 Image quality E.454 E.458 Figure of merit E.450 General aspects E.456 Test transactions Metrics methodologies E.457 Measurement methodologies T0206790-971d01 Figure 1E.450 - Roadmap for E.450-Series Recommendations - Facsimile quality of ser
20、vice 2 Introduction The following aspects of facsimile performance issues are considered: i) connection establishment and disconnection; 2) message transmission; 3) Facsimile terminal performance issues not related to the network are not considered in this Recommendation. Uniformly, the terminology
21、of Recommendations T.30 and T.4 have been employed. In the following clauses, each of these major issues are considered in detail. methods and procedures for facsimile performance characterization. Recommendation E.450 (03/98) 1 - - STD*ITU-T RECMN E.450-ENGL 1998 m 48b2591 Ob47070 7T9 3 Connection
22、establishment and disconnection Facsimile connection establishment is described as phase A in clauses 2lT.30 and 3l.30. Usually in the PSTN (see Notes 1 and 2) no distinction is made between the connection establishment and the disconnection performance for voice and facsimile calls. NOTE 1 - Certai
23、n Administrations give special treatment to facsimile by special numbering or access methods. Such special treatments could produce performance issues that are different from those of normal PSTN facsimile calls. These special treatments are not considered here. NOTE 2 - It is assumed that in manual
24、 operation at the receive terminai there are no operator errors or equipment malfunction after off-hook and that the CED is transmitted as specified in Recommendation T.30. In automatic operation, it is assumed that the machine is working and goes off-hook and transmits the CED signal. It is further
25、 assumed that the terminals operate in accordance with all other aspects of Recommendation T.30. The following parameters can be studied under connection establishment: 1) start dial signal delay and post dialling delay (using the terminology in Recommendation E.431 for calls on PSTN); 2) facsimile
26、phase A completion rate. 3.1 Start dial signal delay and post dialling delay Start Dial Signal Delay (SDSD) and Post Dialling Delay (PDD) issues for voice and facsimile are similar for PSTN calls (see Note 1 in clause 3). At present, we shall follow Recommendation E.431 for these parameters. 3.2 Fac
27、simile phase A completion rate Usually the facsimile phase A completion rate is the same as the call completion rate for voice calls (see Notes 1 and 2 in clause 3 and see the Note below). NOTE - There could be facsimile phase A completion failures because of interaction between the network and facs
28、imile protocol. The phase A completion rate depends on such factors as end-to-end blocking, dialling of the correct number by the customer (see Notes 1 and 2 in clause 3), the ability of the network to deliver the call to the correct B-party number without wrong numbers, etc. Voice call completion r
29、ates are extensively studied in other E-Series Recommendations and will therefore not be studied separately except in those cases where there is a facsimile specific issue. 4 Message transmission The key performance parameters considered under message transmission are: 1) facsimile call cut-Offs (ph
30、ases B through D, as described in clauses 2m.30 and 3lT.30); 2) facsimile modem speed and transaction times; 3) facsimile image quality as impacted by transmission impairments. Facsimile call cut-Offs (phases B through D) are discussed in detail in Recommendation E.451. In that Recommendation a set
31、of rules for facsimile test calls are formulated. Based on these test calls, certain types of call failure modes are discussed and cut-off ratios defined. Facsimile modem speed metrics and transaction times are studied under Recommendation E.452. Facsimile modem speed reductions and increased transa
32、ction time are important parameters when measuring the performance of networks carrying group 3 facsimile. The purpose of Recommendation E.452 is to develop modem speed and transaction time metrics that can be used to describe the performance of transmission networks with respect to group 3 facsimil
33、e. 2 Recommendation E.450 (03/98) - STD*ITU-T RECMN E.450-ENGL 1398 = 4862593 Ob47073 630 Recommendation E.453 defines metics for facsimile image quality based on the impact of transmission impairment induced scan line errors. Page and transaction metics are defined based on the number and distribut
34、ion of errored scan lines. Recommendation E.458 defines a figure of ment. In that Recommendation, facsimile transaction types have been classified in seven categories depending on whether the transaction was completed without cut-Offs, whether or not the speed dropped down and whether or not there w
35、as degradation in image quality. Recommendation E.454 defines several transmission mettics for error correction mode facsimile. Performance parameters defined in Recommendations E.451, E.452 and E.453 have been modified to accommodate the error correction and partial page characteristics of ECM facs
36、imile. Recommendation E.456 defines test transactions for characterizing facsimile transmission performance. Recommendation E.457 provides an overview of various measurement methodologies for G3 facsimile transmission performance. That Recommendation evaluates the advantages and disadvantages of tes
37、t-call based, non-intrusive, mixed-mode and terminal based measurements. Test planning aspects including planning approach, measurement topology, test location points, and some statistical aspects are described. Recommendation E.45 9 defines measurements and metrics for characterizing facsimile tran
38、smission performance using non-intrusive techniques. Non-intrusive measurements are typically made from within a network and derive data from the signals exchanged by the communicating fax terminals. Large amounts of data can be collected providing a broad view of network performance. Non-intrusive
39、data may be impacted by customer behaviour and networlterminal interactions. Annex A Glossary of terms and abbreviations for E.450-Series Recommendations CED CFR CIG CNG CPE CRP CSI CTC CTR DCN DCS DIS DTC ECM EOM EOP EOR ERR Called Station Identification Confirmation to Receive Calling Subscriber I
40、dentification Calling Tone Customer Premises Equipment Command Repeat Called Subscriber Identification Continue to Correct Response to Continue to Correct Disconnect Digital Command Signal Digital Identification Signal Digital Transmit Command Error Correction Mode End-of-Message End-of-Procedure En
41、d-O f-Retransmission Response for End-of-Retransmission Recommendation E.450 (03/98) 3 - STD-ITU-T RECMN E.450-ENGL IT98 4862593 Ob47072 577 FCF FCS FIF FTT HDLC LCS MCF MPS NSC NSF NSS PACR PDD PIN PIP PIS PPR PPS PFU PSTN RNR RTN RTP Facsimile Control Field Frame Check Sequence Facsimile Informati
42、on Field Failure to Train High-level Data Link Control Line Conditioning Signals Message Confirmation Multipage Signal Non-Standard Facilities Command Non-Standard Facilities Non-Standard facilities Set-up Phase A Completion Rate Post Dialling Delay Procedure Interrupt Negative Procedure Interrupt P
43、ositive Procedure Interrupt Signal Partial Page Request Partial Page Signal Procedure Interrupt Public Switched Telephone Network Receiver Not Ready Retrain Negative Retrain Positive 4 Recommendation E.450 (03/98) ienes A ienes B ieries C ieries D ;cries E ;enes F Series G Series H Series I Series J
44、 Series K Series L Series M Series N Series O Series P Series Q Series R Series S Series T Series U Series V Series X Series Y Series 2 ITU-T RECOMMENDATIONS SERIES Organization of the work of the ITU-T Means of expression: definitions, symbols, classification General telecommunication statistics Ge
45、neral tariff principles Overall network operation, telephone service, service operation and human factors Non-telephone telecommunication services Transmission systems and media, digital systems and networks Audiovisual and multimedia systems Integrated services digital network Transmission of telev
46、ision, sound programme and other multimedia signals Protection against interference Construction, installation and protection of cables and other elements of outside plant TMN and network maintenance: international transmission systems, telephone circuits, telegraphy, facsimile and leased circuits M
47、aintenance: international sound programme and television transmission circuits Specifications of measuring equipment Telephone transmission quality, telephone installations, local line networks Switching and signalling Telegraph transmission Telegraph services terminal equipment Terminals for telematic services Telegraph switching Data communication over the telephone network Data networks and open system communications Global information infrastructure Programming languages Printed in Switzerland Geneva, 1998
