1、INTERNATIONAL TELECOMMUNICATION UN ION ITU=T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU v.34 SERIES V: DATA COMMUNICATION OVER THE TELEPHONE NETWORK Interfaces and voiceband modems (02/98) A modem operating at data signalling rates of up to 33 600 bitls for use on the general switched telephone
2、 network and on leased point-to-point 2-wire telephone-type circuits ITU-T Recommendation V.34 (Previously CCITT Recommendation) - STDmITU-T RECMN V.34-ENGL 1998 W 48b2591 Ob50733 760 ITU-T V-SERIES RECOMMENDATIONS DATA COMMUNICATION OVER THE TELEPHONE NETWORK General V.1-V.9 I Wideband modems v.35-
3、v.39 Error control Transmission quality and maintenance I v.40-v.49 v.50-v.59 Simultaneous transmission of data and other signals Interworking with other networks V.lOeV.199 V.60-V.99 Interface layer specifications for data communication Control procedures Modems on digital circuits V.200-V.249 V.25
4、0-V.299 v.300-v.399 For firrther details, please refer to ITU-T List of Recommendations. ITU-T RECOMMENDATION V.34 A MODEM OPERATING AT DATA SIGNALLING RATES OF UP TO 33600 bit/s FOR USE ON THE GENERAL SWITCHED TELEPHONE NETWORK AND ON LEASED POINT-TO-POINT 2-WIRE TELEPHONE-TYPE CIRCUITS Source ITU-
5、T Recommendation V.34 was revised by IT-T Study Group 16 (1997-2000) and was approved under the WTSC Resolution No. 1 procedure on the 6th of February 1998. Recommendation V.34 (02/98) - STD-ITU-T RECMN V.34-ENGL 1998 W 4862593 Ob50735 533 H FOREWORD IT (International Telecommunication Union) is the
6、 United Nations Specialized Agency in the field of telecommuni- cations. The IT Telecommunication Standardization Sector (IT-T) is a permanent organ of the IT. The IT-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardiz
7、ing telecommunications on a worldwide basis. The World Telecommunication Standardization Conference (WTSC), which meets every four years, establishes the topics for study by the IT-T Study Groups which, in their turn, produce Recommendations on these topics. The approval of Recommendations by the Me
8、mbers 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 ITLJ-Ts purview, the necessary standards are prepared on a collaborative basis with IS0 and IEC. NOTE In this Recommendation, the expression “Administration“ i
9、s used for conciseness to indicate both a telecommunication administration and a recognized operating agency. 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 Intellectual Property Righ
10、t. 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 had received notice of inte
11、llectual 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 1998 All rights reserved. No part of this
12、 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. 11 Recommendation V.34 (02/98) STD-ITU-T RECMN V.34-ENGL 1998 4862591 0650736 V7T CONTENTS Page 1 Scope 1 2 References 2
13、 3 Definitions 2 4 Abbreviations . 3 5 Line signals . 4 5.1 Data signalling rates 4 5.2 Symbol rates 4 5.3 Carrier frequencies 4 5.4 Pre-emphasis . 5 6 DTE interfaces 7 6.1 Synchronous interfacing (primary channel only) 8 6.2 Asynchronous character-mode interfacing 8 6.3 Haif-duplex mode interfacing
14、 . 9 6.4 Electrical characteristics of interchange circuits . 9 6.5 Fault condition on interchange circuits . 9 6.6 Thresholds and response times of Circuit 109 9 7 Scrambler 10 8 Framing . 10 . 8.1 Overview . 10 8.2 Mapping fiame switching . 11 8.3 Multiplexing of primary and auxiliary channel bits
15、 11 9 Encoder . 13 9.1 Signal constellations 13 9.2 Mapping parameters 14 9.3 Parser . 17 9.4 Shell mapper . 18 9.5 Differential encoder 20 9.6 Mapper, precoder and trellis encoder 20 9.7 Non-linear encoder 24 10 Start-up signals and sequences . 25 1 O . 1 Signals and sequences used in duplex operat
16、ion . 25 10.2 Signals and sequences used in half-duplex operation . 36 11 Duplex operating procedures 11.1 Phase 1 -Network interaction 1 1.2 Phase 2 - Probindranging 11.3 Phase 3 - Equalizer and echo canceller training . 11.4 Phase 4 - Final training . 11.5 Retrains . 1 1.6 Rate renegotiation . 11.
17、7 Cleardown . 11.8 Two-wire leased line operation . 40 40 41 44 46 49 49 52 52 . Recommendation V.34 (02/98) 111 12 Half-duplex operating procedures 12.1 Phase 1 -Network interaction 12.2 Phase 2 - Probing 12.3 Phase 3 - Primary channel equalizer training . 12.5 Primary channel resynchronization pro
18、cedure . i 12.6 Control channel resynchronization procedure . 12.7 Primary channel retrains . 12.8 Control channel retrains 12.4 Control channel start-up 13 Testing facilities . 14 Glossary Variables and Parameters used in Data mode (clauses 5 to 9) A.l Introduction . A.2 MP sequences for modem cont
19、rol channel compatibility . A.3 Auxiliary channel protocol for modem control . A.4 Items for further study . 14.1 Annex A - V.34 modem control channel procedures Page 53 53 53 57 57 60 61 63 63 64 64 64 66 66 66 67 72 iv Recommendation V.34 (02/98) Recommendation V.34 A MODEM OPERATING AT DATA SIGNA
20、LLING RATES OF UP TO 33600 bit/s FOR USE ON THE GENERAL SWITCHED TELEPHONE NETWORK AND ON LEASED POINT-TO-POINT 2-WIRE TELEPHONE-TYPE CIRCUITS (revised in 1998) 1 Scope This modem is intended for use on connections on General Switched Telephone Networks (GSTNs) and on point-to- point 2-wire leased t
21、elephone-type circuits. The principal characteristics of the modem are as follows: duplex and half-duplex modes of operation on GSTN and point-to-point 2-wire leased circuits; channel separation by echo cancellation techniques; Quadrature Amplitude Modulation (QAM) for each channel with synchronous
22、line transmission at selectable symbol rates including the mandatory rates of 2400, 3000, and 3200 symbolsh and the optional rates of 2743, 2800 and 3429 symbolds; synchronous primary channel data signalling rates of: - 33 600 bids (Optional); - 3 1 200 bids (Optional); - 28 800bids; - 26400 bids; -
23、 24000bids; - 21 600 bids; - 19 200 bids; - 16 800 bids; - 14 400 bids; - 12000bids; - 9600 bids; - 7200 bids; - 4800 bids; - 2400 bids; trellis coding for all data signalling rates; an optional auxiliary channel with a synchronous data signalling rate of 200 bids, a portion of which may be provided
24、 to the user as an asynchronous secondary channel; adaptive techniques that enable the modem to achieve close to the maximum data signalling rate the channel can support on each connection; exchange of rate sequences during start-up to establish the data signalling rate; automoding to V-Senes modems
25、 supported by V.32 bis automode procedures and Group 3 facsimile machines. Recommendation V.34 (02/98) 1 STDmITU-T RECMN V.34-ENGL 1998 4862591 Ob50739 189 2 References The following Recommendations and other references contain provisions which, through reference in this text, constitute provisions
26、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 this Recommendation are therefore encouraged to investigate the possibility of applying the most recent editions of the Recommendatio
27、ns and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. ITU-T Recommendation T.30 (1996), Procedures for document facsimile transmission in the general switched telephone network. IW-T Recommendation V.8 (1998), Procedures for starting sessio
28、ns of data transmission over the public switched telephone network. ITU-T Recommendation V. 1 O (1 993), Electrical characteristics for unbalanced double-current interchange circuits operating at data signalling rates nominally up to 1 O0 kbitls. ITU-T Recommendation V. 1 1 (1 996), Electrical chara
29、cteristics for balanced double-current interchange circuits operating at data signalling rates up to 1 O Mbitls. ITU-T Recommendation V. 14 (1 993), Transmission of start-stop characters over synchronous bearer channels. CCITT Recommendation V.21 (1984), 300 bits per second duplex modem standardized
30、 for use in the general switched telephone network. IT-T Recommendation V.24 (1 996), List of definitions for interchange circuits between Data Terminal Equipment (DTE) and Data Circuit-terminating Equipment (DCE). IT-T Recommendation V.25 (1 996), Automatic answering equipment and general procedure
31、s for automatic calling equipment on the general switched telephone network including procedures for disabling of echo control devices for both manually and automatically established calls. ITU-T Recommendation V.28 (1 993), Electrical characteristics for unbalanced double-current interchange circui
32、ts. ITU-T Recommendation V.32 (1993), A family of 2-wire, duplex modems operating at data signalling rates of up to 9600 bids for use on the general switched telephone network and on leased telephone-type circuits. CCITT Recommendation V.32 bis (1991), A duplex modem operating at data signalling rat
33、es of up to 14400 bits for use on the general switched telephone network and on leasedpoint-to-point 2-wire telephone-type circuits. ITU-T Recommendation V.42 (1 996), Error-correcting procedures for DCEs using asynchronous-to-synchronous conversion. CCITT Recommendation V.54 (1988), Loop test devic
34、es for modems. IS0 21 10: 1989, Information technology - Data communication - 25-pole DTE/DCE interface connector and contact number assignments. ISO/IEC 1 1569: 1993, Information technology - Telecommunications and information exchange between systems - 26-pole interface connector mateability dimen
35、sions and contact number assignments. Definitions This Recommendation defines the following terms. 3.1 auxiliary channel: A 200 bids data channel which, along with the primary channel, is multiplexed into the bit stream transmitted by the modem. Data conveyed in the auxiliary channel is independent
36、from the primary channel and may consist of secondary channel data and modem control data. Modem control channel procedures that may be used between consenting modems are detailed in Annex A. 3.2 constellation shaping: A method for improving noise immunity by introducing a non-uniform two- dimension
37、al probability distribution for transmitted signal points. The degree of constellation shaping is a function of the amount of constellation expansion. 2 Recommendation V.34 (02/98) 3.3 transmission. data mode modulation parameters: Parameters determined during start-up and used during data mode 3.4
38、frame switching: A method for sending .a fractional number of bits per mapping frame, on average, by alternating between sending an integer b - 1 bits per mapping frame and b bits per mapping frame according to a periodic switching pattern. 3.5 analysed by the modem and used to determine data mode m
39、odulation parameters. 3.6 nominal transmit power: Reference transmit power that is configured by the user. A modem that has negotiated a transmit power reduction in Phase 2 of the start-up procedures is said to be transmitting below the Nominal Transmit Power. line probing: A method for determining
40、channel characteristics by sending periodic signals, which are 3.7 by introducing a non-uniform two-dimensional (2D) signal point spacing. non-linear encoding: A method for improving distortion immunity near the perimeter of a signal constellation 3.8 distortion. Equalization is performed at the tra
41、nsmitter using precoding coefficients provided by the remote modem. precoding: A non-linear equalization method for reducing equalizer noise enhancement caused by amplitude 3.9 amplitude distortion. The pre-emphasis filter is selected using a filter index provided by the remote modem. 3.10 stream tr
42、ansmitted by the modem. pre-emphasis: A linear equalization method where the transmit signal spectrum is shaped to compensate for primary channel: The main data channel which, together with auxiliary channel data, constitutes the bit 3.11 recipient modem: The modem which receives primary channel dat
43、a in half-duplex mode. 3.12 3.13 which involves partitioning a two-dimensional signal constellation into rings containing an equal number of points. 3.14 secondary channel: A portion of the auxiliary channel that is made available to the user. shell mapping: A method for mapping data bits to signal
44、points in a multi-dimensional signal constellation, source modem: The modem which transmits primary channel data in half-duplex mode. 3.15 trellis encoding: A method for improving noise immunity using a convolutional coder to select a sequence ofsubsets in a partitioned signal constellation. The tre
45、llis encoders used in this Recommendation are all four-dimensional (4D) and they are used in a feedback structure where the inputs to the trellis encoder are derived from the signal points. 4 Abbreviations This Recommendation uses the following abbreviations: abs 1 AMP CCITT CME CRC DCE DPSK DTE GPA
46、 GPC GSTN IEC Absolute value Auxiliary channel Multiplexing Pattern International Telegraph and Telephone Consultative Committee Circuit Multiplication Equipment Cyclic Redundancy Check Data Circuit-terminating Equipment Differential Phase Shift Keying Data Terminal Equipment Generating Polynomial -
47、 Answer modem Generating Polynomial - Call modem General Switched Telephone Network International Electrotechnical Commission Recommendation V.34 (02/98) 3 IS0 ITU-T LSB MSB QAM QPSK RTDEa RTDEc SWP 5 5.1 International Organization for Standardization Intemational Telecommunication Union - Telecommu
48、nication Standardization Sector Least Significant Bit Most Significant Bit Quadrature Amplitude Modulation Quadrature Phase Shift Keying Round Trip Delay Estimate - Answer modem Round Trip Delay Estimate - Call modem Switching Pattern Line signals Data signalling rates The primary channel shall supp
49、ort synchronous data signalling rates of 2400 bids to 33 600 bitfs in multiples of 2400 bids. An auxiliary channel with a synchronous data signalling rate of 200 bids may also be optionally supported. The primary and auxiliary data signalling rates shall be determined during Phase 4 of modem start-up according to the procedures described in 11.4 or 12.4. The auxiliary channel shall be used only when the call and answer modems have both declared this capability. The primary channel data signalling rates can be asymmetric. 5.2 Symbol rates The symbol rate shall be
