1、 STD-ETSI PRI-ETS 300 837-ENGL 1777 = 3400855 0377708 OLi3 ELECOMMUNICATION STANDARD DRAFT pr I-ETS 300 837 March 1997 Source: ETSI TC-TE Reference: DVMTA-004033 ICs: 33.020 Key words: Coding, multimedia, PSTN Public Switched Telephone Network (PSTN); Terminals for low bit-rate Multimedia communicat
2、ion ETSI European Telecommunications Standards Institute ETSI Secretariat Postal address: F-O6921 Sophia Antipolis CEDEX - FRANCE Office address: 650 Route des Lucioles - Sophia Antipolis - Valbonne - FRANCE X.400: c=fr, a=atlas, p=etsi, s=secretariat - Internet: secretariat Qetsi.fr Tel.: +33 4 92
3、94 42 O0 - Fax: +33 4 93 65 47 16 Copyright Notification: No part may be reproduced except as authorized by written permission. The copyright and the foregoing restriction extend to reproduction in all media. O European Telecommunications Standards Institute 1997. All rights reserved. STDeETSI PRI-E
4、TS 300 837-ENGL 1977 3400855 0377709 T8T Page 2 Draft prl-ETS 300 837: March 1997 Whilst every care has been taken in the preparation and publication of this document, errors in content, typographical or otherwise, may occur. If you have comments concerning its accuracy, please write to “ETSI Editin
5、g and Committee Support Dept.“ at the address shown on the title page. Page 3 Draft prl-ETC 300 837: March 1997 STD-ETSI PRI-ETS 300 837-ENGL 1777 W 3400855 OL777LO 7TL W Contents Foreword . 7 Introduction 7 1 Scope 9 Block diagram and functional elements . 9 System elements outside the scope of thi
6、s LETS . 9 1.1 1.2 1.3 Functional elements covered by this LETS . 10 2 Normative references 11 3 Definitions and abbreviations 12 3.1 Definitions 12 3.2 Abbreviations . 13 3.3 Conventions . 14 4 Functional requirements 14 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 Required elements . 14 Information streams . 1
7、5 Modem . 15 4.4.1 4.4.2 Multiplex table entries 16 4.4.3 Flow control . 16 4.4.4 Error control . 16 4.4.5 Adaptation layers . 16 Control channel 16 4.5.1 Capabilities exchange . 17 4.5.2 Logical channel signaling 18 4.5.3 Mode preferences . 19 4.5.4 Interface to multiplex . 19 4.5.5 Timer and count
8、er values and protocol errors 19 Video channels 19 4.6.1 Interface to multiplex . 20 Audio channels 21 4.7.1 Delay compensation 21 4.7.2 Maximum delay jitter . 22 4.7.3 Interface to multiplexer 22 Data channels 22 4.8.1 Data protocols . 23 4.8.1.1 Buffered ITU-T Recommendation V.14 . 24 4.8.1.2 LAPM
9、ATU-T Recommendation V.42 . 24 4.8.1.3 HDLC frame tunneling . 25 4.8.1.4 Transparent data . 25 4.8.2 Data applications . 25 4.8.2.1 ITU-T Recommendation T.120 multimedia teleconferencing applications 26 4.8.2.2 ITU-T Recommendation T.84 (SPIFF) point-to-point still image transfer cutting across appl
10、ication borders . 26 4.8.2.3 ITU-T Recommendation T.434 point-to-point telematic file transfer cutting across application borders 27 4.8.2.4 ITU-T Recommendation H.224 real-time control protocol, for ITU-T Recommendation H.281 far-end camera control.27 4.8.2.5 Network link layer 27 4.8.2.6 External
11、data ports and unspecified user data 27 Multiplexing 15 Logical channel numbers 15 STDmETSI PRI-ETS 300 837-ENGL 1997 3q00855 DL77711 b38 m Page 4 Draft prl-ETS 300 837: March 1997 5 6 7 8 9 Terminal procedures . 28 5.1 Phase A - call set-up of voiceband channel 28 5.2 Phase B - initial analogue tel
12、ephony communication : . 28 5.2.1 ITiJ-T Recommendation V.8 lo procedure 28 5.2.2 ITU-T Recommendation V.8bis procedure 28 Phase C - establishment of digital communication, modem training 28 5.3.1 ITU-T Recommendation V.8 lo procedure 28 5.3.2 ITU-T Recommendation V.8bis procedure . 29 Phase D . ini
13、tialization . 29 5.4.1 Exchange of video by mutual agreement . 30 Phase E - communication . 30 5.5.1 Rate changes and retrains 30 5.5.2 Involuntary disconnection . 30 Phase F - end of session 30 Phase G - change of communication mode and call clearing . 30 5.3 5.4 5.5 5.6 5.7 Interoperation with oth
14、er terminals . 31 ETS 300 145 multimedia telephone terminals attached to the ISDN 31 Multimedia telephone terminals over mobile radio 31 6.1 6.2 6.3 Speech only terminals . 31 Optional enhancements 32 7.1 Data facilities . 32 7.2 Encryption . 32 7.2.1 EncryptionSE messages . 32 7.2.2 EIV channel 32
15、7.2.3 Encryption procedure 33 7.2.4 Encryption initialization vectors . 33 7.2.5 Error recovery . 34 7.3 Multilink . 34 Multipoint considerations 34 8.1 Establishment of common mode . 34 8.2 Multipoint rate matching 34 8.3 Multipoint lip synchronization . 35 8.4 Multipoint encryption 35 8.5 Cascaded
16、 MCU operation . 35 Maintenance . 35 9.1 Loopbacks for maintenance purposes 35 9.1.1 Normal mode 35 9.1.2 System loopback 35 9.1.3 Media loopback . 35 9.1.4 Logical channel loopback . 35 Annex A (normative): Protocol stack for control channel 37 A.l General . 37 A.2 SRP mode 38 SRP command frames 38
17、 SRP response frames . 38 SRP procedure at transmitter 38 A.2.1 A.2.2 A.2.3 A.2.4 SRP procedure at receiver 39 A.3 LAPMATU-T Recommendation V.42 mode 39 Annex B (normative): HDLC Frame structure transparency for asynchronous transmission . 40 . STD-ETSI PRI-ETS 300 837-ENGL 1777 m 3400855 0177712 i7
18、4 m Page 5 Draft prl-ETS 300 837: March 1997 Bit and octet order 41 Annex C (informative): Annex D (informative): ITU-T Recommendation V.8bis codepoints 42 Annex E (informative): Bibliography . 43 History 44 STDmETSI PRI-ETS 300 837-ENGL 1777 m 3400855 0177713 Li00 m Page 6 Draft pri-ETS 300 837: Ma
19、rch 1997 Blank page Page 7 Draft prl-ETS 300 837: March 1997 STD-ETSI PRI-ETS 300 837-ENGL 1997 3Li00855 017771Li 3q7 = Foreword This draft Interim European Telecommunication Standard (I-ETS) has been produced by the Terminal Equipment (TE) Technical Committee of the European Telecommunications Stan
20、dards Institute (ETSI), and is now submitted for the Public Enquiry phase of the ETSI standards approval procedure. An ETSI standard may be given LETS status either because it is regarded as a provisional solution ahead of a more advanced standard, or because it is immature and requires a “trial per
21、iod“. The life of an LETS is limited to three years after which it can be converted into an ETS, have its life extended for a further two years, be replaced by a new version, or be withdrawn. Proposed announcement date Date of latest announcement of this I-ETS (doa): 3 months after ETSI publication
22、Introduction This I-ETS describes terminals for low bit-rate multimedia communication, utilizing ITU-T Recommendation V.34 15 modems connected to the Public Switched Telephone Network (PSTN). The terminals described in this I-ETC may carry real-time voice, data, and video, or any combination, includ
23、ing videotelephony . Terminals described in this I-ETS may be integrated into personal computers or implemented in stand-alone devices such as videotelephones. Support for each media type (voice, data, video) is optional, but if supported, the ability to use a specified common mode of operation is r
24、equired, so that all terminals supporting that media type can interwork. This LETS allows more than one channel of each type to be in use. ITU-T Recommendations relating to the present document are: H.223 l, H.245 2, H.263 4, and G.723.1 3. This LETS makes use of the logical channel signaling proced
25、ures of ITU-T Recommendation H.245 2, in which the content of each logical channel is described when the channel is opened. Procedures are provided for expression of receiver and transmitter capabilities, so transmissions are limited to what receivers can decode, and so that receivers may request a
26、particular desired mode from transmitters. Since the procedures of ITU-T Recommendation H.245 2 are also planned for use by ITU-T Recommendation H.310 (see annex E) for ATM networks, and ITU-T Recommendation H.323 (see annex E) for non-guaranteed bandwidth LANs, interworking with these systems shoul
27、d be straightforward. Terminals described in this LETS may be used in multipoint configurations through MCUs, and may interwork with ETS 300 145 22 terminals on the ISDN, as well as with terminals on wireless networks. STD-ETSI PRI-ETS 300 837-ENGL 1797 3L100855 DI77715 283 Page 8 Draft prl-ETS 300
28、837: March 1997 Blank page STD-ETSI PRI-ETS 300 837-ENGL 1777 m 3400855 OL777Lb LLT m Pane 9 Draft prl-ETS 300 837: March 1997 1 Scope This Interim European Telecommunication Standard (LETS) covers the technical requirements for very low bit-rate multimedia telephone terminals connected to the Publi
29、c Switched Telephone Network (PSTN). , Interworking with visual telephone systems on the Integrated Services Digital Network (ISDN) (described in ETS 300 145 22) and on mobile radio networks (known as the drafi ITU-T Recommendation H.324 26/M series of Recommendations) are also covered. Terminals de
30、scribed in this LETS provide real-time video, audio, or data, or any combination, between two multimedia telephone terminals over a PSTN voice band network connection. Communication may be either 1 -way or 2-way. Multipoint communication using a separate Multipoint Control Unit (MCU) among more than
31、 two terminals described in this I-ETS is possible. MCUs and other non-terminal devices are not bound by the requirements in this I-ETS, but they should comply where practical. The multimedia telephone terminals defined in this LETS can be integrated into PCs or workstations, or be stand-alone units
32、. I Audiocodec 1 n _ ITU-T RW. I Audio I/O equipment 1-1 G.723.1 3 .! Data protocols ITU-T Rec. V.14 li, LAPM, etc. User data applications I I Control protocol i procedures I System control I I I l I I I l I I l Modem V.“. op,jona, i ITU-T H.223 I I Recs. I l V. 34/ I V.8bis j I I MCU 15. 291 Modem
33、control I ITU-T Rec. ITU-TRec. I Multiplex/ Demultiplex - 15. 101 I ITU-T Rec. l I I l Figure 1 : Block diagram of generic multimedia videophone system 1.1 Block diagram and functional elements A generic multimedia videophone system is shown in figure 1. It consists of terminal equipment, a PSTN mod
34、em, PSTN network, MCU and other system operational entities. Implementations complying with this LETS are not required to have each functional element. NOTE: Functions for interworking with a normal telephone are not depicted. The support of such a function is described in subclause 6.1. 1.2 System
35、elements outside the scope of this I-ETS The following system elements, covered by other ETSI (I-)ETSs and ITU-T Recommendations, are not subject to standardization, or are for other reasons outside the scope of this LETS: - video I/O equipment including cameras and monitors, their control and selec
36、tion, video processing to improve compression or provide split-screen functions; STD-ETSI PRI-ETS 300 837-ENGL 2777 3400855 OL777L7 05b 9 Page 10 Draft prl-ETS 300 837: March 1997 - audio Il0 equipment including handset or other types of acoustic cabinets, microphone(s) and loudspeaker(s), telephone
37、 instrument or equivalent, attached audio devices providing voice activation sensing, multiple microphone mixers, acoustic echo cancellation. NOTE 1 : The audio characteristics of handset telephones supporting the analogue telephony services on the PSTN are normally subject to type approval by natio
38、nal regulatory authorities. LETS 300 677 24 contains information about relevant national values and a proposed harmonized value for the audio characteristics of a handset telephone when attached to the PSTN. NOTE 2: There are no requirements in this LETS for the audio characteristics of a terminal c
39、ommunicating in a multimedia mode. Until such requirements are available, manufacturers are recommended to use LETS 300 245-2 23 as a guide. - data application equipment such as computers, non-standardized data application protocols, telematic visual aids such as electronic whiteboards, etc; - PSTN
40、network interface supporting appropriate signaling, ringing functions and network termination. Human user system control, user interface and operation. 1.3 Functional elements covered by this I-ETS The scope of this LETS is indicated by the elements within the dashed line of figure I, which include:
41、 - the Video Codec (according to ITU-T Recommendations H.263 4 or H.261 5) carries out redundancy reduction coding and decoding for video streams; - the Audio Codec (according to ITU-T Recommendation G.723.1 SI) encodes the audio signal from the microphone for transmission, and decodes the audio cod
42、e which is output to the speaker. Optional delay in the receiving audio path compensates for the video delay, so as to maintain audio and video synchronization; - the Data Protocols support data applications such as electronic whiteboards, still image transfer, file exchange, database access, audiog
43、raphics conferencing, remote device control, network protocols, etc. Standardized data applications include ITU-T Recommendation T.120 17 for real-time audiographics conferencing, ITU-T Recommendation T.84 16 simple point-point still image file transfer, ITU-T Recommendation T.434 la simple point-po
44、int file transfer, ITU-T Recommendations H.224 8/H.281 9 far-end camera control, ISOAEC TR9577 25 network protocols including Point-to-Point Protocol (PPP), Internet Protocol (IP) and transport of user data using buffered ITU-T Recommendations V.14 ll or V.42 13. Other applications and protocols may
45、 also be used via ITU-T Recommendation H.245 2 negotiation; - the Control Protocol (ITU-T Recommendation H.245 2) provides end-to-end signaling for proper operation of the terminal described in this I-ETS, and signals all other end-to-end system functions including reversion to analogue speech-only
46、telephony mode. It provides for capability exchange, signaling of channels; - the Multiplex Protocol (ITU-T Recommendation H.223 l) multiplexes transmitted video, audio, data and control streams into a single bit stream, and demultiplexes a received bit stream into various multimedia streams. In add
47、ition, it performs logical framing, sequence numbering, error detection, and error correction by means of retransmission, as appropriate to each media type; the Modem (ITU-T Recommendation V.34 15) converts the ITU-T Recommendation H.223 l synchronous multiplexed bit stream into an analogueue signal
48、 that can be transmitted over the PSTN, and converts the received analogue signal into a synchronous bit stream that is sent to the Multiplex/Demultiplex protocol unit. ITU-T Recommendation V.25ter 12 is used to provide control/sensing of the modem/network interface, when the modem with network sign
49、aling and ITU-T Recommendation V.8 lON.8bis (see annex E) functional elements is a separate physical item. - Page 11 Draft prl-ETS 300 837: March 1997 STD-ETSI PRI-ETS 300 837-ENGL 1777 m 3900855 01777L T72 m 2 Normative references This LETS incorporates by dated and undated reference, provisions from other publications. These normative references are cited at the appropriate places in the text and the publications are listed hereafter. For dated references, subsequent amendments to or revisions of any of
