1、 - STD-ITU-T RECMN V=5b TER-ENGL 177b Li8b257L Ob28388 778 = INTERNATIONAL TELECOMMUN CATION UN ION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU V.56 ter (08/96) SERIES V: DATA COMMUNICATION OVER THE TELEPHONE NETWORK Transmission quality and maintenance Test procedure for evaluation of 2-w
2、ire 4-kHz voiceband duplex modems ITU-T Recommendation V.56 ter (Previously “CCITT Recommendation“) ITU-T V-SERIES RECOMMENDATIONS DATA COMMUNICATION OVER THE TELEPHONE NETWORK 1 - General 2 - Interfaces and voiceband modems 3 - Widebandmodems 4 - Errorcontrol 6 - Interworking with other networks Il
3、 For further details, please refer to ITU-T List of Recommendations. FOREWORD The ITU-T (Telecommunication Standardization Sector) is a permanent organ of the International Telecommunication Union (ITU). The ITU-T is responsible for studying technical, operating and tariff questions and issuing Reco
4、mmen- 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 Study Groups which, in their turn, produce Recommendations on these t
5、opics. The approval of Recommendations by the Members of the ITU-T is covered by the procedure laid down in WTSC ResolutionNo. 1 (Helsinki, March 1-12, 1993). ITU-T Recommendation V.56fer was prepared by ITU-T Study Group 14 (1993-1996) and was approved under the WTSC Resolution No. 1 procedure on t
6、he 16th of August 1996. NOTES 1. telecommunication administration and a recognized operating agency. In this Recommendation, the expression “Administration” is used for conciseness to indicate both a 2. follows: The status of annexes and appendices attached to the Series V Recommendations should be
7、interpreted as - - an annex to a Recommendation forms an integral part of the Recommendation; an appendix to a Recommendation does not form part of the Recommendation and only provides some complementary explanation or information specific to that Recommendation. O ITU 1997 All rights reserved. No p
8、art 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 the ITU. Recommendation V.56 ter (08/96) 1 CONTENTS Page 1 Scope 1 2 Normative references . 1 3 Definitions 2 4 Requir
9、ements 4 4.1 Network simulator 4 4.2 DTEs . 4.2.1 Functions . 4.2.2 Interface requirements . 4.2.4 DTE transmission performance 4.2.5 Flow control 4.3 Modems . 4.3.2 Flow control 4.3.3 Forced modes of operation Indication of establishment of connection 4.2.3 Pori rate requirements . 4.3.1 Compressio
10、n mode 4.4 4 4 5 5 5 5 5 5 5 5 6 5 Network model coverage considerations . 6 6.1.2 6.1.3 6 Test procedures 6.1 Throughput versus network model coverage File-based with compression . 6.1 . 1 6.1.1.1 Overview . 6.1.1.2 DTE configuration 6.1.1.3 Modem configuration 6.1.1.5 Test procedure . 6.1.1.6 Resu
11、lts . File-based without compression 6.1.2.1 Overview . 6.1.2.2 DTE configuration 6.1.2.3 Modem configuration 6.1.2.4 Network simulator configuration 6.1.2.5 Test procedure . 6.1.2.6 Results . Pattem-based without compression 6.1.3.1 Overview . 6.1.3.2 DTE configuration 6.1.3.3 Modem configuration 6
12、.1.3.4 Network simulator configuration 6.1.3.5 Test procedure . 6.1.3.6 Results . Throughput versus file type 6.2.1 Overview . 6.2.2 DTE configuration 6.2.3 Modem configuration 6.2.4 Network simulator configuration 6.2.5 6.2.6 Test procedure -Two-way transfer 6.1.1.4 Network simulator configuration
13、6.2 Test procedure - One-way transfer . 6.2.7 Results . 6 7 7 7 8 8 8 8 8 8 8 9 9 9 9 9 9 9 10 10 10 10 10 10 10 11 11 11 11 11 12 11 Recommendation V.56 ter (08/96) 6.3 6.4 6.5 6.6 Error ratio versus network model coverage Bit- and block-mor ratio versus network model coverage . 6.3.1.1 Overview .
14、6.3.1.2 DTE configuration 6.3.1.3 Modem configuration 6.3.1.4 Network simulator configuration 6.3.1.5 Test procedure . 6.3.1.6 Results . Message-error ratio versus network model coverage 6.3.2.1 Overview . 6.3.2.2 DTE configuration 6.3.2.3 Modem configuration 6.3.1 6.3.2 6.3.2.4 Network simulator co
15、nfiguration 6.3.2.5 Test procedure . 6.3.2.6 Results . 6.4.1 Overview . 6.4.3 Connect reliability versus test loop combinations 6.4.2 DE configuration Modem configuration L. 6.4.4 Network simulator configuration 6.4.5 Test procedure . 6.4.6 Results . Character echo delay . 6.5.1 Overview . 6.5.2 DTE
16、 configuration 6.5.3 Modem configuration 6.5.4 Network simulator configuration 6.5.5 Test procedure . 6.5.6 Results . Block acknowledge delay . 6.6.1 Overview . 6.6.2 DTE configuration 6.6.3 Modem configuration 6.6.4 Network simulator configuration 6.6.5 Test procedure . 6.6.6 Results . Annex A . DT
17、E verification procedures Annex B . Description of data files . Appendix I . Characteristics of data files Appendix II . Determination of reference throughput values Appendix XII III . 1 111.2 111.3 111.4 111.5 111.6 111.7 . Error rate estimation Definitions Test duration . Application to bit-error
18、rate Application to block-error rate . Procedure Cautions Bibliography . Appendix IV . Data reporting format and interpretation of results . IV.1 Throughput versus network model coverage IV.2 IV.3 Error ratio versus network model coverage IV.4 Connect reliability versus test loop combinations IV.5 C
19、haracter echo delay . Throughput versus file fype IV.6 Block acknowledge delay . Recommendation V.56 ter (08196) Page 12 13 13 13 13 13 13 14 14 14 14 14 14 15 15 15 15 15 15 15 16 16 17 17 17 17 17 17 18 18 18 18 18 19 19 19 20 21 21 24 25 25 26 26 27 27 27 28 29 29 38 39 50 53 53 . 111 STDeITU-T R
20、ECMN V-5b TER-ENGL L77b m Lib257L b28373 035 Appendix V . Call initiation considerations v . 1 v . 2 v.3 Appendix VI Duplex bandsplitting modems Duplex echo-cancelling modems. . Normative test procedure rationale . - RTSKTS flow control . Appendix VI1 . Modem overview . VII . 1 vII.2 Operating modes
21、 . Review of modem functionality Appendix iv VII.2.1 Synchronous mode VII.2.2 Direct mode . VII.2.3 Buffered mode VII.2.4 Error control mode VII.2.5 Compression mode VIII - Circuit identification cross-reference Recommendation V.56 ter (08/96) Page 59 59 59 60 60 60 61 62 62 63 63 64 65 67 STD-ITU-T
22、 RECMN V*5b TER-ENGL L77b E 48b257L Ob28374 T7L Foreword This Recommendation is intended to provide a common basis for comparison of modem performance. Different test procedures described in this Recommendation emphasize different modem applications. The Throughput versus network model coverage test
23、 procedure, for example, is important for evaluating modem performance when used in asynchronous file transfer applications; the Error Rate versus Network Model Coverage test procedure is important for evaluating modem performance in synchronous or asynchronous network applications. No single test i
24、s comprehensive enough to determine which modem will perform best in all applications, but this series of tests permits the gathering of sufficient data on a modem to determine its strengths and weaknesses. Individual users shall decide which factors are important for their particular application or
25、 applications. There are two annexes and eight appendices in this Recommendation. Annexes A and B are normative and are considered part of this Recommendation; Appendices I through VI11 are informative and are not considered part of this Recommendation. Introduction Because of the lack of consistent
26、 test procedures and criteria for interpretation of results, modem performance evaluations historically have resulted in widely varying modem comparisons. This Recommendation was adopted from the ANSI TIA TSB-38 “Test Procedure for Evaluation of 2-wire 4-kilohertz voiceband duplex modems”, which was
27、 created by TIA TR-30.3 to resolve this problem. This Recommendation provides a consistent set of repeatable test procedures designed to characterize the performance of modems. This is achieved by stating the precise configuration of all the required test equipment, then giving step-by- step instruc
28、tions for performing each test. This Recommendation also suggests some formats for analysing, interpreting, and presenting the results. Recommendation V.56 ter (OW96) V STD=ITU-T RECMN V.5b TER-ENGL 177b Lib2571 b28375 908 I Recommendation V.56 ter TEST PROCEDURE FOR EVALUATION OF 2-WIRE 4- IrHZ VOI
29、CEBAND DUPLEX MODEMS (Geneva, 1996) 1 Scope This Recommendation specifies the procedures for testing 2-Wire 4-m Voiceband Duplex Modems that operate over the Public Switched Telephone Network (PSTN). These procedures apply regardless of the manufacturer, type, or implementation of the modem. Due to
30、ongoing developments within ITU Study Group (SG) 14 in the fields of modems, future enhancements of this Recommendation with regard to: - compression of synchronous data; - - DTE-DCE interface matters; and - startuptimes, simultaneous voice and data modems; are likely to take place. 2 Normative refe
31、rences The following Recommendations and other references contain provisions that, 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
32、of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent editions of the Recommendations and other references listed below. A list of currently valid ITU-T Recommendations is regularly published. CCITT Recommendation O. 15 1 ( 1992), Error performanc
33、e measuring equipment operating at the primary rate and above. CCITT Recommendation V. 1 (1972), Equivalence between binary notation symbols and the signcant conditions of a two-condition code. ITU-T Recommendation V. 14 (1993), Transmission of start-stop characters over synchronous bearer channels.
34、 ITU-T Recommendation V.24 (1993), List of dejnitions for interchange circuits between Data Terminal Equipment (DTE) and Data Circuit-Terminating Equipment (DCE). CCITT Recommendation V.25 bis (1988), Automatic calling andor answering equipment on the General Switched Telephone Network (GSTN) using
35、the 1 OO-series interchange circuits. ITU-T Recommendation V.25 ter (1995), Serial asynchronous automatic dialling and control. ITU-T Recommendation V.42 (1 993), Error-correcting procedures for DCEs using asynchronous-to- synchronous conversion. CCITT Recommendation V.42 bis (1 990), Data compressi
36、on procedures for Data Circuit-Terminating Equipment (DCE) using error correction procedures. - ITU-T Recommendation V. 56 bis (1995), Network transmission model for evaluating modem performance over 2-wire voice grade connections. ANSI X3.4-1986, Coded character set - 7-Bit American National Standa
37、rd Code for Information Interchange (referred to herein as 2SCIIy. ANSI X3.15-1976 (R1983), Bit Sequencing of the American National Standard Code for Information Interchange in serial-by-bit data transmission. ANSI X3.16-1976 (R1983), Character structure and character parity sense for serial-by-bit
38、data communication in the American National Standard Code for Information Interchange. - - - - - - - - - - - Recommendation V.56 ter (08/96) 1 - ANSIEIA/TIA-232-E-l99 1 , Interface between data terminal equipment and data circuit-terminating equipment employing serial binary data interchange. ANSIEI
39、A-404-A- 1986, Standard for start-stop signal quality for non-synchronous data terminal equipment. ANSVEIA-449-1984, General purpose 3 7-position and 9-position interface for data terminal equipment and data circuit-terminating equipment employing serial binary data interchange. ANSVEIAfIA-530-A-199
40、2, High speed 25-position interface for data terminal equipment and data circuit-terminating equipment, including alternative 26-position connector. ANSIEIAiTIA-56 1 - 1990, Simple BER Ratio of erroneous bits to total bits received at a DTE-to-modem interface. 3.4 block: Group of contiguous bits. 3.
41、5 block-error ratio; BLER: Ratio of erroneous blocks to total blocks received at a DTE-to-modem interface. 3.6 British Telecom Ziv-Lempel; BTLZ Compression algorithm used in Recommendation V.42 bis. NOTE - The order of the letters “LZ” and the name “Ziv-Lempel” is not a typographical error. 3.7 buff
42、ered mode; normal mode: Mode of data transmission whereby the V.24 circuits 103 (transmit data) and 104 (receive data) transfer data at a port rate independent of the line rate. The difference in transfer rates is compensated for by buffering data as required in the modem. Neither error correction p
43、rotocols nor data compression algorithms are used. For modem modulation methods which transfer data synchronously, V. 14 synchronoushsynchronous conversion is used within the modem. 3.8 byte: Group of 8 contiguous bits; octet. 3.9 character: For bit-serial interfaces, a group of five to eight contig
44、uous data bits that is preceded by one start (condition Z, space) bit and followed by at least one complete stop (condition A, mark) bit; a parity bit appearing between the final data bit and the first (or only) stop bit is optional. For bit-parallel interfaces, a character is equivalent to a byte.
45、3.10 compression mode: Mode of data transmission whereby the ITU-T circuits 103 (transmit data) and 104 (receive data) transfer characters of data at a DTE port rate independent of the modem-to-modem line rate, and the transferred information is then transformed inside the modem by a compression alg
46、orithm. information is transferred reliably between modems using V.42 error control, and is compressed by using V.42 bis compression. 3.11 compression ratio: Ratio of the size of the original data to the size of the compressed data. 3.12 may have two DTE ports and, therefore, constitute two DTEs. da
47、ta terminal equipment; DTE: Equipment comprising a data source and a data sink. A single computer 3.13 BTLZ coding dictionary. dictionary size: V.42 bis negotiated parameter Pl that specifies the maximum number of elements in the 2 Recommendation V.56 ter (08196) STD-ITU-T RECMN V-56 TER-ENGL 1776 =
48、 48b257L Ob28378 bL7 = 3.14 direct mode: Mode of data transmission whereby the V.24 circuits 103 (transmit data) and 104 (receive data) transfer data at a port rate equal to the line rate. The modem does not buffer data in either direction, nor does the modem implement flow control. For modem modula
49、tion methods that transfer data synchronously, this mode implies the use of V. 14 synchronous/asynchronous protocol within the modem. 3.15 data simultaneously over the modem-to-modem channel. duplex modem; full duplex modem: Modem classification denoting the modems ability to send and receive 3.1 6 end office-to-end office impairment combinations; EO-EO combinations; IC: Combinations of impair- ments that build together with the Test Loop Combinations (TLC) a test channel for the modem under test. The EO-EO combinations are specified in Recommenda
