1、STD-ETSI I-ETS 300 837-ENGL 1998 m 3Y00855 0270327 79T W v INTERIM EUROPEAN T I ELECOMMUNICATION STANDARD I=ETS 300 837 January 1998 Source: MTA Reference: Di/MTA-004033 ICs: 33.020 Key words: Coding, multimedia, PSTN Public Switched Telephone Network (PSTN); Terminals for low bit-rate multimedia co
2、mmunication ETSI European Telecommunications Standards institute ETSI Secretariat Postai address: F-O6921 Sophia Antipolis CEDEX - FRANCE Office address: 650 Route des Lucioles - Sophia Antipolis - Valbonne - FRANCE X.400: c=fr, a=atias, p=etsi, s=secretariat - Internet: secretariatQetsi.fr Tel.: +3
3、3 4 92 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. Q European Telecommunications Standards Institute 1998. All rights reserved. STD-ETS
4、I I-ETS 300 837-ENGL 1778 m 300855 0270328 82b D Page 2 I-ETS 300 837: January 1998 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 Edit
5、ing and Committee Support Dept.“ at the address shown on the title page. . STDmETSI I-ETS 300 837-ENGL 1778 3Li00855 0270327 7b2 M Page 3 I-ETS 300 837: January 1998 Contents . Foreword .“-. -. 7 Introduction . . . 7 1 Scope . 9 1.1 1.2 1.3 Block diagram and functional elements . 9 Functional elemen
6、ts covered by this LETS . 10 System elemdnts outside the scope of this LETS . 9 2 Normative references . ._._. 11 3 Definitions and abbreviations . 12 3.1 Definitions 12 3.2 Abbreviations . 13 3.3 Conventions -.- 14 4 Functional reauirements . . 14 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 Required elements 1
7、4 Multiplexing . - 15 Information streams . 15 Modems 15 4.4.1 Logical channel numbers 15 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 signalling 18 4.5.3 Mode
8、preferences . 19 4.5.4 Interface to multiplex . 19 4.5.5 Timer and counter 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 pro
9、tocols . 23 4.8.1.1 Buffered ITU-T Recommendation V.14 . 24 4.8.1.2 LAPM / ITU-T Recommendation V.42 . 24 4.8.1.3 HDLC frame tunnelling 25 4.8.1.4 Transparent data . 25 4.8.2 Data applications . 25 4.8.2.1 ITU-T Recommendation T.120 multimedia 4.8.2.2 4.8.2.3 4.8.2.4 4.8.2.5 4.8.2.6 teleconferencing
10、 applications 26 IT-T Recommendation T.84 (SPIFF) point-to-point still image transfer cutting across application borders . 26 ITU-T Recommendation T.434 point-to-point telematic file transfer cutting across application borders 26 ITU-T Recommendation H.224 real-time control protocol. for ITU-T Recom
11、mendation H.281 far-end camera control . 27 Network link layer 27 External data ports and unspecified user data 27 5 Terminal procedures . 27 STD-ETSI I-ETS 300 837-ENGL 1498 3q00855 0270330 q8i Page 4 i-ETS 300 837: January 1998 5.1 5.2 Phase A . call set-up of voiceband channel 28 Phase B . initia
12、l analogue telephony communication 28 5.2.1 ITU-T Recommendation V.8 l O 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 procedure . 28 5.3.2 ITU-T Recommendation V.8bis procedure . 29 Ph
13、ase D - initialization 29 5.4.1 Exchange of video by mutual agreement . 29 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 6 Interoperati
14、on with other terminals 31 6.1 Speech only terminals 31 6.2 ETC 300 145 multimedia telephone terminals attached to the ISDN 31 6.3 Multimedia telephone terminals over mobile radio 31 7 Optional enhancements 31 7.1 Data facilities . 31 7.2 Encryption .- 32 7.2.1 EncryptionSE messages . 32 7.2.2 EIV c
15、hannel 32 7.2.3 Encryption procedure 32 7.2.4 Encryption initialization vectors . 33 7.2.5 Error recovery . 33 . 7.3 Multilink _ 34 8 Multipoint considerations 34 8.1 Establishment of common mode . 34 8.2 Multipoint rate matching . 34 8.3 Multipoint lip synchronization . 43 8.4 Multipoint encryption
16、 . 34 8.5 Cascaded MCU operation . 35 9 Maintenance . 35 9.1 Loopbacks for maintenance purposes 35 9.1.1 Normal mode 35 9.1.3 Media loopback . 35 9.1.4 Logical channel loopback . 35 9.1.2 System loopback 35 Annex A (normative): Protocol stack for control channel 37 A.l General . 37 A.2 SRP mode . 38
17、 A.2.1 SRP command frames 38 A.2.2 SRP response frames 38 A.2.3 SRP procedure at transmitter 38 A.2.4 SRP procedure at receiver . Co A.3 LAPM / ITU-T Recommendation V.42 mode 39 Annex B (normative): HDLC frame structure transparency for asynchronous transmission 40 Annex C (informative): Bit and oct
18、et order . 41 Annex D (informative): ITU-T Recommendation V.8bis codepoints . 42 Annex E (informative): Bibliography 43 STD.ETSI I-ETS 300 837-ENGL 1978 3900855 0270331 310 Page 5 LETS 300 837: January 1998 History . ,. , . . . . . 44 I - STD-ETSI I-ETS 300 837-ENGL 1778 3Li00855 0270332 257 9 Page
19、7 LETS 300 837: January 1998 Foreword This Interim European Telecommunication Standard (I-ETS) has been produced by the Multimedia Terminals and Applications (MTA) Technical Committee of the European Telecommunications Standards Institute (ETSI). An ETSI standard may be given LETS status either beca
20、use it is regarded as a provisional solution ahead of a more advanced standard, or because it is immature and requires a “trial period“. 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 ver
21、sion, or be withdrawn. Announcement date Date of adoption of this I-ETS: Date of latest announcement of this LETS (doa): 2 January 1998 30 April 1998 Introduction This LETS describes terminals for low bit-rate multimedia communication, utilizing ITU-T Recommendation V.34 15 modems connected to the P
22、ublic Switched Telephone Network (PSTN). The terminals described in this I-ETC may carry real-time voice, data, and video, or any combination, including videotelephony. Terminals described in this LETS may be integrated into personal computers or implemented in stand-alone devices such as videotelep
23、hones. Support for each medium type (voice, data, video) is optional, but if supported, the ability to use a specified common mode of operation is required, so that all terminals supporting that medium type can interwork. This I-ETC allows more than one channel of each type to be in use. ITU-T Recom
24、mendations relating to this LETS are: H.223 l, H.245 2, H.263 4 and G.723.1 3. This LETS makes use of the logical channel signalling procedures 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 expressio
25、n of receiver and transmitter capabilities, so transmissions are limited to what receivers can decode, and so that receivers may request a 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
26、 E) for ATM networks, and ITU-T Recommendation H.323 (see annex E) for non-guaranteed bandwidth LANs, interworking with these systems should be straightforward. Terminals described in this LETS may be used in multipoint configurations through Multipoint Control Unit (MCUs), and may interwork with ET
27、S 300 145 22 terminals on the Integrated Services Digital Network (ISDN), as well as with terminals on wireless networks. Previous page is blank STD*ETSI I-ETS 300 B37-ENGL 1998 3400855 U270333 193 M Page 9 I-ETS 300 837: January 1998 1 Scope This Interim European Telecommunication Standard (I-ETS)
28、covers the technical requirements for very low bit-rate multimedia telephone terminals connected to the Public Switched Telephone Network (PSTN). Interworking with visual telephone systems on the Integrated Services Digital Network (ISDN) (described in ETS 300 145 ZZ) and on mobile radio networks (k
29、nown as the ITU-T Recommendation H.324 26/M series of Recommendations) are also covered. Terminals described in this I-ETS 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 on
30、e-way or two-way. Multipoint communication using a separate Multipoint Control Unit (MCU) among more than two terminals described in this LETS 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 tele
31、phone terminals defined in this I-ETS can be integrated into PCs or workstations, or be stand-alone units. ITU-T Rec. Recebe Audio I/O equipment G.723.1 3 path delay Data protocols ITU-T Rec. V.14 Ill), LAPM, etc. User data applications L l I I I System contrd Multiplex! 3ernultiplex H.223 l ITU-T R
32、E. ! Modern TU-T RE V.34V.8 i15, 101 Optional /TU-T ReCS. K3.Y V: 8bis Ils, BJ Modern control FU-T Rm V.25ter 121 I : NOTE: In this diaciram, Rec. means Recommendation. I I l I l I I l I I I I I l I I I I I I I I I I I I I I I l l l I l l I 1.1 Block diagram and functional elements A generic multime
33、dia videophone system is shown in figure 1. It consists of terminal equipment, a PSTN modem, 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 ar
34、e not depicted. The support of such a function is described in subclause 6.1. 1.2 System elements outside the scope of this I-ETS The following system elements, covered by other (I-)ETSs and ITU-T Recommendations, are not subject to standardization, or are for other reasons outside the scope of this
35、 I-ETS: - video input/output equipment including cameras and monitors, their control and selection, video processing to improve compression or provide split-screen functions; Previous page is blank STD-ETSI I-ETS 300 837-ENGL 1998 3900855 0270339 UZT Page 10 LETS 300 837: January 1998 - audio inpuVo
36、utput equipment including handset or other types of acoustic cabinets, microphone(s) and loudspeaker(s), telephone instrument or equivalent, attached audio devices providing voice activation sensing, multiple microphone mixers, acoustic echo cancellation; NOTE 1 : The audio characteristics of handse
37、t telephones supporting the analogue telephony services on the PSTN are normally subject to type approval by national regulatoty authorities. I-ETS 300 677 24 contains information about relevant national values and a proposed harmonized value for the audio characteristics of a handset telephone when
38、 attached to the PSTN. NOTE 2: There are no requirements in this LETS for the audio characteristics of a terminal communicating 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 compute
39、rs, non-standardized data application protocols, telematic visual aids such as electronic whiteboards, etc.; - PSTN network interface supporting appropriate signalling, ringing functions and network I termination. Human user system control, user interface and operation. 1.3 Functional elements cover
40、ed by this I-ETS The scope of this LETS is indicated by the elements within the dashed line of figure 1, which include: - 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 IT
41、U-T Recommendation G.723.1 SI) encodes the audio signal from the microphone for transmission, and decodes the audio code 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
42、 support data applications such as electronic whiteboards, still image transfer, file exchange, database access, audiographics conferencing, remote device control, network protocols, etc. Standardized data applications include ITU-T Recommendation T.120 17 for real-time audiographics conferencing, I
43、TU-T Recommendation T.84 16 simple point-point still image file transfer, ITU-T Recommendation T.434 18 simple point-point file transfer, ITU-T Recommendations H.224 8/H.281 9 far-end camera control, ISO/IEC TR9577 25 network protocols including Point-to-Point Protocol (PPP), Internet Protocol (IP)
44、and transport of user data using buffered ITU-T Recommendations V.14 ll or V.42 13. Other applications and protocols may also be used via ITU-T Recommendation H.245 2 negotiation; - the Control Protocol (ITU-T Recommendation H.245 2) provides end-to-end signalling for proper operation of the termina
45、l described in this I-ETS, and signals all other end-to-end system functions including reversion to analogue speech-only telephony mode. It provides for capability exchange, signalling of channels; - the Multiplex Protocol (ITU-T Recommendation H.223 l) multiplexes transmitted video, audio, data and
46、 control streams into a single bit stream, and demultiplexes a received bit stream into various multimedia streams. In addition, 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 Re
47、commendation V.34 15) converts the ITU-T Recommendation H.223 l synchronous multiplexed bit stream into an analogue signal 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 Rec
48、ommendation V.25ter 12 is used to provide control/sensing of the modem/network interface, when the modem with network signalling and ITU-T Recommendation V.8 10YV.8bis (see annex E) functional elements is a separate physical item. Page 11 I-ETS 300 837: January 1998 2 Normative references This LETS
49、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 these publications apply to this LETS only when incorporated in it by amendment or revision. For undated references the latest edition of the publication referred to applies. I11 ITU-T Recomme
