1、INTERNATIONAL TELECOMMUNICATION UNIONITU-T V.92TELECOMMUNICATIONSTANDARDIZATION SECTOROF ITU(11/2000)SERIES V: DATA COMMUNICATION OVER THETELEPHONE NETWORKSimultaneous transmission of data and other signalsEnhancements to Recommendation V.90ITU-T Recommendation V.92(Formerly CCITT Recommendation)ITU
2、-T V-SERIES RECOMMENDATIONSDATA COMMUNICATION OVER THE TELEPHONE NETWORKGeneral V.1V.9Interfaces and voiceband modems V.10V.34Wideband modems V.35V.39Error control V.40V.49Transmission quality and maintenance V.50V.59Simultaneous transmission of data and other signals V.60V.99Interworking with other
3、 networks V.100V.199Interface layer specifications for data communication V.200V.249Control procedures V.250V.299Modems on digital circuits V.300V.399For further details, please refer to the list of ITU-T Recommendations.ITU-T V.92 (11/2000) iITU-T Recommendation V.92Enhancements to Recommendation V
4、.90SummaryDigital and analogue modems for use on the Public Switched Telephone Network (PSTN) at datasignalling rates up to 56 000 bit/s downstream and up to 48 000 bit/s upstream, with reduced start-uptime on recognized connections, and procedures to support modem-on-hold in response tocall-waiting
5、 events or outgoing call requests.SourceITU-T Recommendation V.92 was prepared by ITU-T Study Group 16 (2001-2004) and approvedunder the WTSA Resolution 1 procedure on 17 November 2000.ii ITU-T V.92 (11/2000)FOREWORDThe International Telecommunication Union (ITU) is the United Nations specialized ag
6、ency in the field oftelecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ ofITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendationson them with a view to standardizing telecommunications on a worldwide b
7、asis.The World Telecommunication Standardization Assembly (WTSA), which meets every four years,establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on thesetopics.The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolut
8、ion 1.In some areas of information technology which fall within ITU-Ts purview, the necessary standards areprepared on a collaborative basis with ISO and IEC.NOTEIn this Recommendation, the expression “Administration“ is used for conciseness to indicate both atelecommunication administration and a r
9、ecognized operating agency.INTELLECTUAL PROPERTY RIGHTSITU draws attention to the possibility that the practice or implementation of this Recommendation mayinvolve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence,validity or applicability of claimed Int
10、ellectual Property Rights, whether asserted by ITU members or othersoutside of the Recommendation development process.As of the date of approval of this Recommendation, ITU had received notice of intellectual property,protected by patents, which may be required to implement this Recommendation. Howe
11、ver, implementors arecautioned that this may not represent the latest information and are therefore strongly urged to consult theTSB patent database. ITU 2001All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means,electronic or mechanical, including
12、 photocopying and microfilm, without permission in writing from ITU.ITU-T V.92 (11/2000) iiiCONTENTSPage1 Scope 12 References 13 Definitions 24 Abbreviations . 35 Digital modem 36 Analogue modem 36.1 Data signalling rates . 36.2 Symbol rate. 36.3 Scrambler36.4 Transmitter . 36.4.1 Modulus encoder .
13、46.4.2 Precoder and prefilter 56.4.3 Inverse map . 56.4.4 Convolutional encoder 67 Interchange circuits 67.1 List of interchange circuits . 67.2 Asynchronous character-mode interfacing. 68 Signals and sequences 68.1 Full Phase 1 68.2 Short Phase 1 signals and sequences for the analogue modem 78.2.1
14、QC1a 78.2.2 QC2a 88.2.3 QCA1a. 88.2.4 QCA2a. 88.2.5 TONEq 98.3 Short Phase 1 signals and sequences for the digital modem 98.3.1 ANSpcm 98.3.2 QC1d . 148.3.3 QC2d . 148.3.4 QCA1d 158.3.5 QCA2d 158.3.6 QTS . 168.4 Full and short Phase 2 signals and sequences 168.4.1 INFO information bits. 168.5 Phase
15、3 signals for the analogue modem 21iv ITU-T V.92 (11/2000)Page8.5.1 CPt. 218.5.2 E1u. 228.5.3 MD 228.5.4 Ja228.5.5 Ru. 238.5.6 Su. 238.5.7 TRN1u238.6 Phase 3, signals for the digital modem. 238.6.1 DIL 238.6.2 Jd238.6.3 Jp248.6.4 Jp. 258.6.5 Ri. 258.6.6 SCR . 258.6.7 Sd. 258.6.8 TRN1d258.7 Phase 4,
16、Rate Renegotiation and Fast Parameter Exchange signals for theanalogue modem. 268.7.1 B1u. 268.7.2 E2u. 268.7.3 CPu268.7.4 RM298.7.5 SUVu. 308.7.6 TRN2u318.7.7 FB1u. 328.8 Phase 4, Rate Renegotiation and Fast Parameter Exchange signals for the digitalmodem 328.8.1 B1d. 328.8.2 Ed. 328.8.3 CPd328.8.4
17、 R 368.8.5 SUVd. 368.8.6 TRN2d378.9 Modem-on-hold 378.9.1 RT 378.9.2 MH sequences . 37ITU-T V.92 (11/2000) vPage9 Operating procedures 399.1 Full Phase 1 Network interaction 399.2 Short Phase 1 Network interaction 399.2.1 Call modem is analogue modem . 419.2.2 Call modem is digital modem . 429.2.3 A
18、nswer modem is analogue modem . 429.2.4 Answer modem is digital modem 439.2.5 ODP/ADP bypass 439.3 Full Phase 2 Probing/ranging 439.3.1 ODP/ADP bypass 449.4 Short Phase 2 Ranging. 449.4.1 Digital modem. 449.4.2 Analogue modem 459.5 Phase 3 Equalizer and echo canceller training and digital impairment
19、 learning. 469.5.1 Digital modem. 479.5.2 Analogue modem 489.6 Phase 4 Final training 499.6.1 Digital modem. 519.6.2 Analogue modem 529.7 Retrains. 539.7.1 Digital modem. 539.7.2 Analogue modem 539.8 Rate renegotiation. 539.8.1 Digital modem. 559.8.2 Analogue modem 569.9 Fast parameter exchange 579.
20、9.1 Digital modem. 579.9.2 Analogue modem 589.10 Modem-on-hold 589.10.1 Transmission of MH sequences 589.10.2 Modem-on-hold transactions. 599.11 Cleardown.6210 Testing facilities . 62ITU-T V.92 (11/2000) 1ITU-T Recommendation V.92Enhancements to Recommendation V.901ScopeThis Recommendation specifies
21、 the operation between two different modems, one a digital modemand the other an analogue modem, both as defined in clause 3. The two modems are specified hereinin terms of coding, start-up signals and sequences, operating procedures and DTE-DCE interfacefunctionality. The network interface of the d
22、igital modem and the signalling rate that is used toconnect the digital modem locally to a digital switched network are considered to be national mattersand are hence not specified herein. The principal characteristics of these modems are as follows:a) duplex mode of operation on the PSTN;b) channel
23、 separation by echo cancellation techniques;c) PCM modulation in both directions at a symbol rate of 8000;d) synchronous channel data signalling rates in the downstream direction from 28 000 bit/s to56 000 bit/s in increments of 8000/6 bit/s;e) synchronous channel data signalling rates in the upstre
24、am direction from 24 000 bit/s to48 000 bit/s in increments of 8000/6 bit/s;f) adaptive techniques that enable the modems to achieve close to the maximum data signallingrates the channel can support on each connection;g) negotiate V.34 modulation upstream (downstream) if a connection will not suppor
25、t PCMmodulation upstream (downstream);h) exchange of rate sequences during start-up to establish the data signalling rate;i) use of V.8, and optionally V.8 bis, procedures during modem start-up or selection;j) reduced start-up time on recognized connections; andk) support of modem-on-hold procedures
26、 in response to call-waiting events or outgoing callrequests.2 ReferencesThe following ITU-T Recommendations and other references contain provisions, which, throughreference in this text, constitute provisions of this Recommendation. At the time of publication, theeditions indicated were valid. All
27、Recommendations and other references are subject to revision;users of this Recommendation are therefore encouraged to investigate the possibility of applying themost recent edition of the Recommendations and other references listed below. A list of the currentlyvalid ITU-T Recommendations is regular
28、ly published. ITU-T G.711 (1988), Pulse code modulation (PCM) of voice frequencies. ITU-T V.8 (2000), Procedures for starting sessions of data transmission over the publicswitched telephone network. ITU-T V.8 bis (2000), Procedures for the identification and selection of common modes ofoperation bet
29、ween data circuit-terminating equipment (DCEs) and between data terminalequipment (DTEs) over the public switched telephone network and on leased point-to-pointtelephone-type circuits.2 ITU-T V.92 (11/2000) ITU-T V.14 (1993), Transmission of start-stop characters over synchronous bearerchannels. ITU
30、-T V.21 (1988), 300 bits per second duplex modem standardized for use in the generalswitched telephone network. ITU-T V.24 (2000), List of definitions for interchange circuits between data terminalequipment (DTE) and data circuit-terminating equipment (DCE). ITU-T V.25 (1996), Automatic answering eq
31、uipment and general procedures for automaticcalling equipment on the general switched telephone network including procedures fordisabling of echo control devices for both manually and automatically established calls. ITU-T V.34 (1998), A modem operating at data signalling rates of up to 33 600 bit/s
32、 for useon the general switched telephone network and on leased point-to-point 2-wiretelephone-type circuits. ITU-T V.42 (1996), Error-correcting procedures for DCEs using asynchronous-to-synchronous conversion. ITU-T V.43 (1998), Data flow control. ITU-T V.80 (1996), In-band DCE control and synchro
33、nous data modes for asynchronousDTE. ITU-T V.90 (1998), A digital modem and analogue modem pair for use on the publicswitched telephone network (PSTN) at data signalling rates of up to 56 000 bit/sdownstream and up to 33 600 bit/s upstream.3 DefinitionsThis Recommendation defines the following terms
34、:3.1 analogue modem: The analogue modem is the modem of the pair that, when in data mode,receives G.711 signals that have been passed through a G.711 decoder. The modem is typicallyconnected to the PSTN.3.2 digital modem: The digital modem is the modem of the pair that, when in data mode,generates G
35、.711 signals. The modem is connected to a digital switched network through a digitalinterface, 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 analoguemodem.3.4 nominal transmit power: Reference tran
36、smit power that is configured by the user.3.5 Qa.b format: Numbers denoted as signed Qa.b are represented in (a + b + 1)-bittwos-complement format with b bits after the binary point, and assume values in the half-openinterval 2a, 2a. Numbers denoted as unsigned Qa.b are represented in (a + b)-bit fo
37、rmat with b bitsafter the binary point, and assume values in the half-open interval 0, 2a + 1.3.6 Ucode: As defined in clause 3/V.90.3.7 upstream: Transmission in the direction from the analogue modem towards the digitalmodem.3.8 LU: The value of LUis set such that TRN1Uis transmitted at the desired
38、 data mode transmitpower.ITU-T V.92 (11/2000) 34 AbbreviationsThis Recommendation uses the following abbreviations:BRI Basic Rate InterfaceDCE Data Circuit-Terminating EquipmentDIL Digital Impairment Learning sequenceDTE Data Terminal EquipmentPRI Primary Rate InterfacePSTN Public Switched Telephone
39、 NetworkRTDEd Round-Trip Delay Estimate digital modem5 Digital modemThe data signalling rates, symbol rate, scrambler and encoder for the digital modem shall be thesame as those given in clause 5/V.90.6 Analogue modem6.1 Data signalling ratesThe modem shall transmit synchronously at data signalling
40、rates of 24 000 bit/s to 48 000 bit/s inincrements of 8000/6 bit/s. The data signalling rate shall be determined during Phase 4 of modemstart-up according to the procedures described in 9.6.6.2 Symbol rateThe upstream symbol rate shall be 8000 symbol/s derived from the digital network.6.3 ScramblerT
41、he analogue modem shall include a self-synchronizing scrambler as specified in clause 7/V.34,using the generating polynomial, GPA, in equation 7-2/V.34.6.4 TransmitterThe framing of the transmitter shall be based upon Figure 1.4 ITU-T V.92 (11/2000)T1609090-00i = 0 1 2 3 4 5 6 7 8 9 10 11j = 0 1 2 3
42、 4 5 0 1 2 3 4 5k = 0 1 2 3 0 1 2 3 0 1 2 3Data frameTrellis frameConstellation frameFigure 1/V.92 Framing structure for the analogue modemFigure 2 is a block diagram of the major elements of the analogue modem transmitter, which aredescribed in detail in 6.4.1 to 6.4.4.T1609100-00Kix(n)y(n)b0:bK1Mi
43、 Y1:Y4Gv(n)Y0precoderprefilterModulusencoderConv.encoderInversemapFigure 2/V.92 Analogue modem transmitter block diagram6.4.1 Modulus encoderFor each data frame, K scrambled bits, denoted by bits b0to bK1, where b0is first in time, enter themodulus encoder. Parameters M0to M11also enter the modulus
44、encoder.The values of Miand K shall satisfy the inequality 2K M = =110iiMThe modulus encoder converts the K bits into twelve numbers, K0to K11, using the followingalgorithm.NOTE Other implementations are possible but the mapping function must be identical to that given in thealgorithm described belo
45、w.1) Represent the incoming K bits as an integer, R:1K1K1102b.2bbR +=ITU-T V.92 (11/2000) 52) Determine the sign of R:()() ()2/1MRif1fs;2/1MRif0s(f) =3) Differentially encode the sign:d(f) = s(f) d(f 1), where represents modulo 2 addition4) Form R0:() ()11fdifR1MR;01fdifRR00=5) Divide R0by M0. The r
46、emainder of this division gives K0, the quotient becomes R1for usein the calculation for the next data frame interval. Continue for the remaining eleven dataframe intervals. This gives K0to K11as:Ki= Rimodulo Mi, where 0 Ki Mi; Ri + 1= (Ri Ki)/Mi6) The numbers K0to K11are the outputs of the modulus
47、encoder, where K0corresponds todata frame interval 0 and K11corresponds to data frame interval 11.6.4.2 Precoder and prefilterThe precoder has inputs from the modulus encoder and the convolutional encoder. For each Kireceived from the modulus encoder, the precoder identifies Kiwith an equivalence cl
48、ass E(Ki). Theprecoder selects a point u(n) from the equivalence class E(Ki). The index of the constellation pointu(n) is denoted by y(n).The equivalence classes are chosen as follows. Let the N constellation points be denoted by a(),N/2 N/2, where the indices are in the same order as the levels. (N
49、 is the appropriateconstellation length taken from the CPdsequence, i.e. one of 2*LC1through 2*LC6in Table 30).Thus negative points have negative indices, and positive points have non-negative indices. Themodulus encoder output Kihas Mipossible values 0 Ki Mi. The equivalence class E(Ki)corresponding to Kiis then defined as:E(Ki) = a(k) | k= Ki+ zkMi, zkan integer for k = 0, 1, 2;a(k) | k= 2Ki+ 2
