1、 - STD-ITU-T RECMN V-70-ENGL L79b 9Bb257L Ob29322 LLb INTERNATIONAL TELECOMMUNICATION UN ION ITU-T TELECOMMUNICATION STAN DARD IZATI ON SECTOR OF ITU - V.70 SERIES V: DATA COMMUNICATION OVER THE TELEPHONE NETWORK Transmission quality and maintenance (08196) Procedures for the simultaneous transmissi
2、on of data and digitally encoded voice signals over the GSTN, or over 2-wire leased point-to-point telephone type circuits ITU-T Recommendation V.70 (Previously “CCITT Recommendation”) - STD-ITU-T RECMN V.70-ENGL L99b 9Bb259L Ob29323 052 W ITU-T V-SERIES RECOMMENDATIONS DATA COMMUNICATION OVER THE T
3、ELEPHONE NETWORK 1 - General 2 - Interfaces and voiceband modems 3 - Widebandmodems 4 - Errorcontrol II 6 - Interworking with other networks - For further details, please refer to ITU-T List of Recommendations. STD-ITU-T RECMN V.70-ENGL L77b m 48bZ57L ObZq324 T77 FOREWORD The ITU-T (Telecommunicatio
4、n Standardization Sector) is a permanent organ of the International Telecommunication Union (ITU). The IT-T is responsible for studying technical, operating and tariff questions and issuing Recommen- dations on them with a view to standardizing telecommunications on a worldwide basis. The World Tele
5、communication 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 topics. The approval of Recommendations by the Members of the ITU-T is covered by the procedure laid down i
6、n WTSC Resolution No. 1 (Helsinki, March 1-12, 1993). ITU-T Recommendation V.70 was prepared by ITU-T Study Group 14 (1993-1996) and was approved under the WTSC Resolution No. 1 procedure on the 16th of August 1996. NOTE 1. telecommunication administration and a recognized operating agency. In this
7、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 interpreted as - an annex to a Recommendation forms an integral part of the Recommendation; - an appendix to
8、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 part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical,
9、including photocopying and microfilm, without permission in writing from the ITU. Recommendation V.70 (08/96) i CONTENTS Page 1 Scope 1 2 Normative references . I 3 Definitions 2 4 Abbreviations . 2 5 DSVD system 5.1 System overview . 5.2 Supervisory and control function . . . . . . . _. . . . 5.3 D
10、ata processing function 5.4 Voice processing function 5.5 Control Entity (CE). . . . . . . . . . . . . . . . . . . . . 5.6 Multiplex function . . . . . . . . _. . . . . . . . . 5.7 Modem 5.8 Summary of requirements and options . - 6 Operating procedures . 7 6.1 DSVD mode hitiation 7 6.2 DSVD mode op
11、eration . 8 6.3 End of DSVD mode 11 7 Interfaces 11 7.1 DTE-DCE data interface . 11 7.2 DTE-DCE control . 11 7.3 Voice interface 11 7.4 Combined datavoice interface . 11 System implementation requirements . . 11 8 9 Interworking . Annex A - UNERM tunnelling procedures Appendix I - Relationship with
12、V.42 LAPM operation Differences between V.76 and V.42 LAPM . Interworking procedures . Appendix II - Alternatives for support of T. 120-based audiographic conferencing using Recommendation V.70 11.1 PSTN basic profile 11.2 Alternative A: PSTN profile-based on Recommendation V.70 with UNERM tunnellin
13、g . 11.3 Altemative B: PSTN profile-based on Recommendation V.70 using V.76 channels 11.4 Altemative C: PSTN profile-based on Recommendation V.70 using V.75 CE primitives Bibliography . . . . . . . . . . . . . . . . , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.1 1.2 11 12 13 13 14 1
14、4 14 15 16 16 17 11 Recommendation V.70 (08/96) STD-ITU-T RECMN V-70-ENGL Lb m 48b259L Ob2432b bl Recommendation V.70 PROCEDURES FOR THE SIMULTANEOUS TRANSMISSION OF DATA AND DIGITALLY ENCODED VOICE SIGNALS OVER THE GSTN, TELEPHONE TYPE CIRCUITS (Geneva, 1996) OR OVER 2-WIRE LEASED POINT-TO-POINT 1
15、Scope This Recommendation describes the technical requirements for a Digital Simultaneous Voice and Data (DSVD) terminal, for operation over the General Switched Telephone Network (GSTN) or 2-wire telephone type leased circuits. The major characteristics of a DSVD terminal are: - the simultaneous tr
16、ansmission of data), e.g. file transfer or T.120 information, and digitally encoded voice signals over a single GSTN connection or over 2-wire leased point-to-point telephone-type circuits; the ability to enter the DSVD operating mode either at call Set-up, or during an analogue telephone connection
17、; multiplexing of bidirectional voice and data channels using a V.42 8 LAPM-based multiplexing technique described in Recommendation V.76 1 i; and - transmission of the multiplexed bit stream using the modulation technique defined in Recommendation V.34 7 or V.32 bis 6. The DSVD terminal may consist
18、 of one physical unit, or alternatively, the functional elements of the terminal may be partitioned between a number of physical units. This Recommendation defines DSVD operation over a point-to-point connection. Multipoint communication may be achieved, for example using a separate multipoint contr
19、ol unit, but the characteristics of this device are not covered by this Recommendation. - - 2 Normative references The following Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, th
20、e 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 edition of the Recommendations and other references listed below. A list of the curr
21、ently valid ITU-T Recommendations is regularly published. 113 Pl 131 ITU-T Recommendation G.729, Annex A*), Reduced complexity 8 kbith CS-ACELP speech coder. IT-T Recommendation H.245 (1 996), Control protocol for multimedia communication. ITU-T Recommendation V.8 bis (1996), Proceduresfor the ident
22、ification and selection of common modes of operation between Data Circuit-Terminating Equipments (DCEs) and between Data Terminating Equipments (DTEs) over the general switched telephone network and on leasedpoint-to-point telephone-ype circuits. CCITT Recommendation V.25 bis (1988), Automatic calli
23、ng and/or answering equipment on the General Switched Telephone Network (GSnV) using the I OO-series interchange circuits. VI 1 See Recommendation H.324 for the simultaneous transmission of audio and video information. *) Presently at the stage of draft. Recommendation V.70 (08/96) 1 STD-ITU-T RECMN
24、 V.70-ENGL L77b 4Bb257L Ob24327 7T8 M ITU-T Recommendation V.25 ter (1995), Serial asynchronous automatic dialling and control. 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
25、point-to-point 2-wire telephone- type circuits. ITU-T Recommendation V.34 (1994), A modem operating at data signalling rates of up to 28 800 bith for use on the general switched telephone network and on Ieasedpoint-to-point 2-wire telephone-type circuits. ITU-T Recommendation V.42 (1993), Error-corr
26、ecting procedures for DCEs using asynchronous-to- synchronous conversion. CCITT Recommendation V.42 bis (1 990), Data compression procedures for Data Circuit-Terminating Equipmenl (DCE) using error correction procedures. ITU-T Recommendation V.75 (1996), DSVD terminal controlprocedures. ITU-T Recomm
27、endation V.16 (1996), Generic multiplexer using V.42 LAPM-basedprocedures. ITU-T Recommendation V.80 (1996), Zn-band DCE control and synchronous data modes for asynchronous DTE. Definitions For the purposes of this Recommendation, the following definitions apply. 3.1 are combined and transmitted in
28、a single multiplex frame. The default value is “1”. 3.2 DSVD terminal: A DCEDTE combination which together comply with the requirements of this Recommendation and its associated Recommendations. All the functionality of a DSVD terminal may be implemented within the DCE alone. audio blocking factor:
29、The number of information blocks, i.e. coded samples, from the speech coder which 3.3 various functions. The role is determined from the V.8 bis procedures and is the same as the initiator role for V.8 bis. 3.4 various functions. The role is determined from the V.8 bis procedures and is the same as
30、the responder role for V.8 bis. initiator: A role taken on by the control entity and multiplex function that determines how it operates for responder: A role taken on by the control entity and multiplex function that determines how it operates for 4 Abbreviations For the purposes of this Recommendat
31、ion, the following abbreviations are used: ADP Answerer Detection Pattern API Application Programming Interface CE Control Entity DCE Data Circuit-Terminating Equipment DLC Data Link Connection DLCI Data Link Connection Identifier DSVD DTE Data Terminal Equipment DTMF Dual Tone Multiple Frequency ER
32、M Error Recovery Mode GSTN General Switched Telephone Network IP internet Protocol Digital Simultaneous Voice and Data 2 Recommendation V.70 (08196) STD-ITU-T RECMN V-70-ENGL 1776 LiBb259L 0bZLi328 b3Li I I I Supervisory Data 7- and control processing I l I function function LAPM MF Multiplex Functi
33、on ODP Chiginator Detection Pattern PPP Point-to-Point Protocol SAP Service Access Point SCF Supervisory and Control Function UNEM Unacknowledged Non-Error Recovery Mode Link Access Procedure for Modems Voice processing function 5 DSVD system I 5.1 System overview A general model of a DSVD terminal
34、is shown in Figure 1. This is an abstract model and is not intended to restrict practical implementations. - Data source Voice source AP l I- I I I I I I I l I I I l I I I I I Network interface T1402790-96IdO1 FIGURE 1N.70 A V.70 system shall include as a minimum the following functional elements, a
35、nd a compliant V.70 implementation is required to incorporate the functionality of each of these elements: Supervisory and Control Function (SCF) The SCF is responsible for the control of the DSVD system (see 5.2). Data processingbnction The data processing function is responsible for converting the
36、 user data into a format suitable for handling by the multiplex function, e.g. the conversion of start-stop framed data to a format suitable for synchronous transmission. The data channel(s) may be synchronous or asynchronous, and the protocols and applications supported may be indicated and negotia
37、ted using the DSVD control entity. Recommendation V.70 (08196) 3 STD-ITU-T RECMN V-70-ENGL L99b 48b259L Ob24329 570 m Voice processingfunction The voice processing function includes a codec compliant with Recommendation G.729 Annex A i for the conversion of voice signals into a digital bit stream an
38、d vice versa. The voice processing function also includes voice activity detection and comfort noise generator, such that periods of silence in voice signals may be used to increase the bit rate available for data communication. The use of alternative speech or audio coders may be negotiated by the
39、SCF using the DSVD control entity. 0 Control Entiv (CE) A DSVD control entity is provided to manage the establishment and release of channels, the exchange of capability and parameter information, the conversion of control information into the H.245 message format, and the transfer of data, voice an
40、d control information to and fiom the multiplex function. 0 Multiplex function (MF) A DSVD terminal makes use of a multiplexing capability described in Recommendation V.76 to combine one or more voice channels with one or more data channels, and an optional out-of-band control channel. Each informat
41、ion bit stream (voice, data and control) is assigned a Data Link Connection (DLC) in the multiplexed bit stream. For all channels, transmission is bidirectional. The multiplexer also provides Came delimiting and protection Com bit corruption. 0 Modem The multiplexed bit stream is transmitted over th
42、e GSTN (or leased circuit) using a V.32 bis 6 or V.34 7 modem, or other future high speed modems to be defined by the ITU. The modem also includes V.8 bis functionality for mode negotiation and selection at call Set-up and during analogue telephony. A DSVD terminal may also include a system control
43、entity for functions such as terminal configuration, assignment of channel priority, capability selection decisions, etc. The requirements of this system control entity are outside the scope of this Recommendation. 5.2 Supervisory and control function The Supervisory and Control Function (SCF) shall
44、 be responsible for: a) requesting a DLC between the DSVD terminal and a remote terminal for the purpose of transferring information as characterized by various parameters; this is achieved using the CE-ESTABLISH primitive; it shall be possible to establish more than one DLC (the maximum number is i
45、mplementation dependent); b) orderly release of a DLC using the CE-RELEASE primitive; c) d) requesting the exchange of terminal capability information using the CE-SETPARh4 primitive; handling of potential collisions of open channel requests. In general these activities are camed out by requesting a
46、nd receiving services from the control entity using the procedures defined in Recommendation V.75 1 O NOTE -The SCF may coordinate the changing of parameters of a voice channel. An example of this is changing the speech coder to one using a different rate. This can be done by negotiating and opening
47、 a new channel using the new speech coder. This may be done before or after releasing the existing channel. However, the procedure should avoid adverse interaction with the application. 5.3 Data processing function The data channel provides for end-to-end transmission of user data. A DSVD terminal s
48、hall be capable of opening at least one data channel. Initiation of the establishment of a data channel is undertaken by the SCF. Asynchronous data may be transmitted over either an ERM or a UNERM channel. Synchronous data shall be transmitted over a UNEM channel. 4 Recommendation V.70 (08196) When
49、a data channel has been established by the SCF, information is transferred from the data processing function to the CE using the CE-DATA request primitive. Where an asynchronous channel is established the data rate shall be dependent on the line signalling rate of the modem, the number of logical channels on the link and the activity on the voice channel. Where multiple asynchronous channels are established, the allocation of priority between these chann
