1、STDmITU-T RECMN V-70-ENGL 1798 48b2571 0655707 T77 INTERNATIONAL TELECOMMUNICATION UNION ITU=T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU v.90 SERIES V: DATA COMMUNICATION OVER THE TELEPHONE NETWORK Simultaneous transmission of data and other signals (O 9/98) A digital modem and analogue modem
2、pair for use on the Public Switched Telephone Network (PSTN) at data signalling rates of up to 56 O00 bitls downstream and up to 33 600 bitls upstream ITU-T Recommendation V.90 (Previously CCITT Recommendation) ITU-T V-SERIES RECOMMENDATIONS DATA COMMUNICATION OVER THE TELEPHONE NETWORK General Inte
3、rfaces and voiceband modems Wideband modems Error control I V.l-V.9 V. 10-V. 34 v.35-v.39 v.40-v.49 I Transmission quality and maintenance v.50-v.59 II Interworking with other networks Interface layer specifications for data communication Control procedures Modems on digital circuits v.lOO-v.199 V .
4、200-V .249 V.250-V.299 v.300-v.399 For further details, please refer to ITU-T List of Recommendations. ITU-T RECOMMENDATION V.90 A DIGITAL MODEM AND ANALOGUE MODEM PAIR FOR USE ON THE PUBLIC SWITCHED TELEPHONE NETWORK (PSTN) AT DATA SIGNALLING RATES OF UP TO 56000 bids DOWNSTREAM AND UP TO 33600 bis
5、 UPSTREAM Summary This Recommendation specifies the operation of a digital modem and analogue modem pair for use on the Public Switched Telephone Network (PSTN) at data signalling rates of up to 56 O00 bit/s in the downstream direction and up to 33 600 bit/s in the upstream direction. The two modems
6、 are specified herein in terms of coding, start-up signals and sequences, operating procedures and DTE-DCE interface functionalities. The network interface of the digital modem and the signalling rate that is used to connect the digital modem locally to a digital switched network are considered to b
7、e national matters and are hence not specified herein. Source ITU-T Recommendation V.90 was prepared by ITU-T Study Group 16 (1997-2000) and was approved under the WTSC Resolution No. 1 procedure on the 25th of September 1998. Recommendation V.90 (09/98) 1 STD-ITU-T RECMN V-SO-ENGL 1798 48b2571 Ob55
8、710 581 D 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 IIU. The ITU-T is responsible for studying technical, operating and tarif
9、f 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 the ITU-T Study Groups which, in their turn, produce
10、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 standards are prepared on a collaborative basis with IS
11、0 and IEC. NOTE In this Recommendation the term recognized operating agency (ROA) includes any individual, company, corporation or governmental organization that operates a public correspondence service. The terms Administration, ROA and public correspondence are defined in the Constitution of ihe I
12、TU (Geneva, 1992). INTELLECTUAL PROPERTY RIGHTS The ITLJ draws attention to the possibility 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
13、 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 intellectual property, protected by patents, which may be required to implement this Recommend
14、ation. 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 1999 All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mech
15、anical, including photocopying and microfilm, without permission in writing from the ITU. _. 11 Recommendation V.90 (09/98) STD-ITU-T RECMN V-SO-ENGL 1978 i8b2591 Ob55911 414 1 2 3 4 5 6 7 8 CONTENTS Scope References Definitions Abbreviations . Digital modem 5.1 Data signalling rates 5.2 Symbol rate
16、 . 5.3 Scrambler 5.4 Encoder . 5.4.1 Mapping parameters 5.4.2 input bit parsing 5.4.3 Modulus encoder . 5.4.4 Mapper 5.4.5 Spectral shaping 5.4.6 Sign assignment . 5.4.7 Mux . Analogue modem 6.1 Data signalling rates 6.3 Carrier frequencies 6.4 Pre-emphasis . 6.6 Framing . interchange circuits . 6.2
17、 Symbol rates 6.5 Scrambler 6.7 Encoder . 7.1 List of interchange circuits 7.2 Asynchronous character-mode interfacing Start-up signals and sequences . 8.1 8.2 8.3 8.4 Phase 1 Phase 2 8.2.1 A 8.2.2 B 8.2.3 INFO sequences Phase 3 signals for the analogue modem 8.3.2 MD 8.3.3 PP 8.3.4 S . 8.3.5 SCR .
18、8.3.6 TRN . Phase 3 signals for the digital modem . 8.4.1 DIL 8.4.2 Jd . 8.4.3 JA . 8.4.5 TRNld . 8.2.4 Line probing signals 8.3.1 Ja . 8.4.4 sd . Recommendation V.90 (09/98) Page 1 1 2 4 5 5 5 5 5 5 6 6 7 7 10 10 10 11 11 11 11 11 11 11 11 11 11 11 12 12 12 12 12 16 16 17 20 20 20 20 20 20 20 21 21
19、 21 22 . 111 8.5 Phase 4 signals for the analogue modem 8.5.1 B1 8.5.2 CP 8.5.3 E Phase 4 signals for the digital modem . 8.6.1 Bld 8.6.2 Ed 8.6.3 MP . 8.6.4 R 8.6.5 TRN2d . 8.6 9 Operating procedures 9.1 9.2 9.3 9.4 9.5 9.6 9.7 Phase 1 . Network interaction 9.1.1 Use of bits in Recommendation V.8 9
20、.1.2 Call modem . 9.1.3 Answer modem Phase 2 - Probinglranging 9.2.1 Digital modem . 9.2.2 Analogue modem Phase 3 - Equaliser and echo canceller training and digital impairment learning 9.3.1 Digital modem . 9.3.2 Analogue modem 9.4.1 Digital modem . 9.4.2 Analogue modem Phase 4 - Final training . R
21、etrains . 9.5.1 Digital modem . 9.5.2 Analogue modem Rate renegotiation . 9.6.1 Digital modem . 9.6.2 Analogue modem Cleardown . 1 O Testing facilities . 1 1 Gloss asr Appendix I - Overview Page 22 22 22 25 25 26 26 26 27 28 28 28 28 29 29 29 30 31 32 32 34 34 35 36 36 36 36 37 37 38 39 39 40 41 iv
22、Recommendation V.90 (09/98) STDVITU-T RECMN V*SO-ENGL 1978 111 48b259L Ob55713 290 W Recommendation V.90 A DIGITAL MODEM AND ANALOGUE MODEM PAIR FOR USE ON THE PUBLIC SWITCHED TELEPHONE NETWORK (PSTN) AT DATA SIGNALLING RATES OF UP TO 56000 bith DOWNSTREAM AND UP TO 33600 bis UPSTREAM (Geneva, 1998)
23、 1 Scope This Recommendation specifies the operation between two different modems, one a digitai modem and the other an analogue modem, both as defined in clause 3. The two modems are specified herein in terms of coding, start-up signais and sequences, operating procedures and DTE-DCE interface func
24、tionalities. The network interface of the digitai modem and the signalling rate that is used to connect the digital modem locally to a digital switched network are considered to be national matters and are hence not specified herein. The principal Characteristics of these modems are as follows: dupl
25、ex mode of operation on the PSTN; channel separation by echo cancellation techniques; PCM modulation in the downstream direction at a symbol rate of 8000; synchronous channel data signalling rates in the downstream direction from 28 O00 bids to 56 O00 bivs in increments of 8000/6 bids; V.34 modulati
26、on in the upstream direction; synchronous channel data signalling rates in the upstream direction from 4800 bih to 28 800 bids in increments of 2400 bids, with optional support for 3 1 200 bids and 33 600 bids; adaptive techniques that enable the modems to achieve close to the maximum data signallin
27、g rates the channel can support on each connection; negotiate full duplex V.34 operation if a connection will not support V.90 operation; exchange of rate sequences during start-up to establish the data signalling rate; automoding to V-series modems supported by V.32 bis automode procedures and grou
28、p 3 facsimile machines; use of V.8, and optionally V.8 bis, procedures during modem start-up or selection. References The following Recommendations contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicat
29、ed were valid. All Recommendations are subject to revision; all users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent editions of the Recommendations listed below. A list of currently valid ITU-T Recommendations is regularly published. - - C
30、CITT Recommendation G.711(1988), Pulse Code Modulation (PCM) of voicefiequencies. ITU-T Recommendation T.30 (1996), Procedures for document facsimile transmission in the general switched telephone network. IT-T Recommendation V.8 (1998), Procedures for starting sessions of data transmission over the
31、 public swiiched telephone network. ITU-T Recommendation V.8 bis (1996), Procedures for the identification and selection of common modes of operation between Data Circuit-terminating Equipments (DCEs) and between Data Terminal Equipments (DTEs) over the public switched telephone network and on lease
32、dpoint-to-point telephone-type circuits. - - Recommendation V.90 (09/98) 1 STD-ITU-T RECMN V-70-ENGL 1778 48b2571 Ob557L4 127 ITU-T Recommendation V. 14 (1993), Transmission of start-stop characters over synchronous bearer channels. ITU-T Recommendation V.24 (1998), List of definitions for interchan
33、ge circuits between Data Terminal Equipment PTE) and Data Circuit-terminating Equipment (DCE). ITU-T Recommendation V.25 (1 996), Automatic answering equipment and general procedures for automatic calling equipment on the general switched telephone network including procedures for disabling of echo
34、control devices for both manually and automatically established calls. CCITT Recommendation V.32 bis (1991), A duplex modem operating at data signalling rates of up to 14 400 bith for use on the general switched telephone network and on leased point-to-point 2-wire telephone-Vpe circuits. ITU-T Reco
35、mmendation V.34 (1998), A modem operating at data signalling rates of up to 33 600 bids 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-synchr
36、onous conversion. - ITU-T Recommendation V.43 (1998), Dataflow control. - IT-T Recommendation V.80 (1996), In-band DCE control and synchronous data modes for asynchronous DTE. 3 Definitions This Recommendation defines the following terms: 3.1 analogue modem: The analogue modem is the modem of the pa
37、ir that, when in data mode, generates V.34 signals and receives G.711 signals that have been passed through a G.711 decoder. The modem is typically connected to a PSTN. 3.2 digital modem: The digital modem is the modem of the pair that, when in data mode, generates G.711 signals and receives V.34 si
38、gnals that have been passed through a G.711 encoder. The modem is connected to a digital switched network through a digital interface, e.g. a Basic Rate Interface (BRI) or a Primary Rate Interface (PRI). 3.3 downstream: Transmission in the direction from the digital modem towards the analogue modem.
39、 3.4 nominal transmit power: Reference transmit power that is configured by the user. 3.5 16 to 3 1; . . .; and Uchords contains Ucodes 1 12 to 127. Uchord: Ucodes are grouped into eight Uchords. Uchordi contains Ucodes O to 15; Uchord2 contains Ucodes 3.6 Ucode: The universal code used to describe
40、both a p-law and an A-law PCM codeword. All universal codes are given in decimal notation in Table 1. The p-law and A-law codewords are the octets to be passed to the digital interface by the digital modem and are given in hexadecimal notation. All modifications defined in Recommen- dation G.7 11 ha
41、ve already been made. The MSB in the p-law PCM and A-law PCM columns in Table 1 corresponds to the polarity bit of the G.711 character signals. A linear representation of each PCM codeword is also given. 3.7 upstream: Transmission in the direction from the analogue modem towards the digital modem. 2
42、 Recommendation V.90 (09/98) Table 1N.90 - The universal set of PCM codewords 37 DA 556 FO 688 1 o1 9A 10876 BO 11008 38 D9 588 F3 720 102 99 11388 B3 11 520 39 D8 620 F2 752 103 98 1 1900 B2 12032 Recommendation V.90 (09/98) 3 STD-ITU-T RECMN V*SO-ENGL 1798 = 48b2571 Ob5571ib TTT = 61 c2 1756 62 c1
43、 1820 63 CO 1884 E8 1888 125 82 30076 A8 30208 EB 1952 126 81 31100 Al3 31232 EA 201 6 127 80 32124 AA 32256 4 Abbreviations This Recommendation uses the following abbreviations: BRI Basic Rate Interface DCE Data Circuit-terminating Equipment DIL Digital Impairment Learning sequence DTE Data Termina
44、i Equipment PRI Primary Rate Interface PSTN Public Switched Telephone Network RMS Root Mean Square RTDEa RTDEd UINFO Round-Trip Delay Estimate - Analogue modem Round-Trip Delay Estimate - Digital modem The Ucode given by bits 2531 of INFO1, 4 Recommendation V.90 (09/98) STD.ITU-T RECMN V-SO-ENGL 179
45、8 48b25SL Ob55917 93b m 5 Digital modem 5.1 Data signalling rates Synchronous channel data signaijing rates from 28 O00 bids to 56 O00 bids in increments of 8000/6 bids shall be supported. The data signalling rate shall be determined during Phase 4 of modem start-up according to the procedures descr
46、ibed in 9.4. 5.2 Symbol rate The downstream symbol rate shall be 8000 established by timing from the digital network interface. The digital modem shall support the upstream symbol rates 3000 and 3200. It may also support the optional upstream symbol rate 3429 as defined in Recommendation V.34. 5.3 S
47、crambler The digital modem shall include a self-synchronizing scrambler as specified in clause 7N.34, using the generating polynomial, GPC, in equation 7-1N.34. 5.4 Encoder The block diagram in Figure 1 is an overview of the encoder and represents one data fiame. Data frames in the digital modem hav
48、e a six-symbol structure. Each symbol position within the data frame is called a data frame interval and is indicated by a time index, i = O, . . ., 5, where i = O is the first in time. Frame synchronization between the digital modem transmitter and analogue modem receiver is established during trai
49、ning procedures. Modulus M;,-p$nt Assign Mux encoder signs - parser Bit I Serial PCM octets Figure 1N.90 - Digital modem encoder block diagram 5.4.1 Mapping parameters Mapping parameters, established during training or rate renegotiation procedures, are: - - - - six PCM code sets, one for each data fiame interval O to 5, where data frame interval i has Mi members; K, the number of modulus encoder input data bits per data frame; S, the number of PCM code sign bits per data fiame used as redundancy for spectral shaping; and S, the number of spectral shaper input data bits per data fra
