ITU-T Q 1111-1993 Interfaces between the INMARSAT Standard B System and the International Public Switched Telephone Network ISDN - Interworking with Satellite Mobile Systems (Study.pdf

1、ITU-T RECMN*Q.LLLL 93 m 4862571 0586369 581 W INTERNATIONAL TELECOMMUNICATION UNION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU INTERWORKING WITH SATELLITE MOBILE SYSTEMS Q.1111 (03/93) INTERFACES BETWEEN THE INMARSAT STANDARD B SYSTEM AND THE INTERNATIONAL PUBLIC SWITCHED TELEPHONE NETWOR

2、WISDN ITU-T Recommendation Q.1111 (Previously “CCITT Recommendation”) FOREWORD The ITU Telecommunication Standardization Sector (-T) is a permanent organ of the International Telecom- munication Union. The ITU-T is responsible for studying technical, operating and tariff questions and issuing Recomm

3、endations on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Conference (WTSC), which meets every four years, established the topics for study by the ITU-T Study Groups which, in their turn, produce Recommendations on these topic

4、s. ITU-T Recommendation Q.1111 was revised by the IT-T Study Group XI (1988-1993) and was approved by the WTSC (Helsinki, March 1-12, 1993). NOTES 1 As a consequence of a reform process within the International Telecommunication Union (ITU), the CCITT ceased to exist as of 28 February 1993. In its p

5、lace, the ITU Telecommunication Standardization Sector (ITU-T) was created as of 1 March 1993. Similarly, in this reform process, the CCIR and the IFRB have been replaced by the Radiocommunication Sector. In order not to delay publication of this Recommendation, no change has been made in the text t

6、o references containing the acronyms “CCIT, CCIR or IFRB” or their associated entities such as Plenary Assembly, Secretariat, etc. Future editions of this Recommendation will contain the proper terminology related to the new ITU structure. 2 telecommunication administration and a recognized operatin

7、g agency. In this Recommendation, the expression “Administration” is used for conciseness to indicate both a O IT 1994 All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without p

8、ermission in writing from the ITU. ITU-T RECMN*Q=LLLZ 93 48b2593 0586373 L3T CONTENTS General . Service capabilities . 2.1 Channel capabilities 2.2 INMARSAT Standard-B bearer capabilities 2.3 Teleservices Interworking scenarios . Connection interface requirements . 4.1 General 4.2 MSSC-network inter

9、face 4.3 SES-MSSC interface 4.4 Terminal to ship earth station interface 4.5 Calling procedures Routing requirements . Maritime and supplementary services 6.1 Maritime services available via INMARSAT . 6.2 Supplementary services Appendix I . INMARSAT Standard-B mobile-satellite system description .

10、1.1 Introduction 1.2 Channel configurations . 1.3 Access control and signalling sub-system 1.5 Link layer formats and protocols 1.6 Telephone services 1.4 Communications sub-system Recommendation Q.1111 (03/93) Page 1 1 1 1 2 2 4 4 4 4 4 5 7 7 7 7 8 8 8 12 13 14 15 i ITU-T RECMN+Q-1111 93 m 4862591

11、0586372 O76 m Recommendation Q.1111 INTERFACES BETWEEN THE INMARSAT STANDARD B SYSTEM AND THE INTERNATIONAL PUBLIC SWITCHED TELEPHONE NETWORWISDN (Melbourne, 1988: modified at Helsinki, 1993) 1 General 1.1 This Recommendation includes information on the services offered in the ISDN relevant to the S

12、tandard-B INMARSAT system and describes the requirements for connection and internetworking with the public networks. Special terminology for this Recommendation is defined in Recommendation Q.1100. Detailed interworking procedures are set out in Recommendation Q.1112. INMARSAT system. 1.2 In additi

13、on to providing the capability to interwork using common channel signalling techniques between the terrestrial ISDN and the Standard-B INMARSAT system, due regard should be paid to the open systems interconnection reference model (X.200-Series Recommendations) and ISDN services and signalling method

14、s (I-Series Recommen- dations) with a view to achieving uniformity in user procedures and formats, and to achieving generally applicable facilities. NOTE - Recommendations Q.1101, Q.1102 and Q.1103 define the interworking procedures for the Standard-A 1.3 Within the constraint of the need to operate

15、 as economically as possible, the preferred interworking cases are with the ISDN and with those parts of the international telephone network employing common channel signalling. If these cases do not exist at the ISC to which an MSSC is connected then another signalling system from the Q-Series Reco

16、mmendations should be used. 1.4 improvements in quality and more flexibility in service. The use of the ISDN for call connect purposes from the MSSC to the fixed user is expected to offer both 2 Service capabilities A general description of the INMARSAT Standard-B system is contained in Appendix I.

17、2.1 Channel Capabilities The system supports a range of channel capabilities as follows: - - single channel per carrier (SCFC) communication channels; time division multiplexhime division multiple access (TDM/TDMA) communication channels and random access (RA) channels with information bit rates of

18、up to 16 kbit/s. Further capabilities may be supported in the future, e.g. channels with information bit rates of up to 64 kbit/s. The services supported by each channel type are indicated in the following subclauses. 2.2 INMARSAT Standard-B bearer capabilities 2.2.1 SCPC channels The following bear

19、er services on SCPC channels with an information transfer rate attribute of 16 kbit/s and 9.6 kbit/s and with the following information transfer attributes corresponding to those defined in Recommendation 1.21 1 should be supported: a) b) Speech at 16 kbit/s and optionally at 9.6 kbit/s. Circuit mod

20、e 3.1 kHz audio services at 16 kbit/s (Transcoding to the circuit mode 64 kbit/s, 8 kHz structured bearer service, usable for 3.1 kHz audio information, of Recommendation 1.21 1, should take place in the MSSC). Recommendation Q.1111 (03/93) 1 c) d) Virtual call bearer service at an information bit r

21、ate of 16 kbit/s. Digitai daa, circuit mode service at an information bit rate up to 9.6 kbit/s for facsimile service. 2.2.2 “DlWTDMA channes The following bearer services on TDh4/TDMA channels should be supported with information transfer rates of 0.05, 0.3 for telex and low speed data respectively

22、: a) b) Telex - Interworking with the ISDN should take place as defined in Recommendation U.202; Virtual call bearer service - Interworking with the ISDN should take place as defined for interworking between PSPDNs and the ISDN; Digital data, circuit mode - Interworking with the PSTN should take pla

23、ce as defined in the appropriate PSTN signalling system; NOTE - Adaptors designed to CCITT Recommendations may not support call set-up for ship earth station terminating calls. This requires further study by INMARSAT. Digital data, asynchronous circuit mode symmetric - For further study by INMARSAT.

24、 Digital data, asynchronous circuit mode, asymmetric - For further study by INMARSAT. c) d) e) 2.2.3 RA channels The following bearer services on random access channels may be supported: a) Connectionless data service - For further study by INMARSAT. 2.3 Teleservices Teleservices should be supported

25、 as defined inRecommendation 1.212. It is to be observed that not all teleservices of ISDN may be supported with bearer services that can be provided on SCPC or TDMfDMA channels operating at net bit rates of 16 kbit/s or less. 3 Interworking scenarios Three interworking scenarios can be envisaged fo

26、r the interface between the MSSC and the fixed networks. 3.1 The first of these is shown in Figure 1. No interworking is envisaged between the MSSC and the ISDN, with the MSSC interfaced directly to the telex, public switched telephone and public data networks. In this scenario interworking with the

27、 PSTN supports speech and 3.1 kHz audio services. n T1155790-9WdOl FIGIRE l/Q. 11 11 Interworking scenario with no ISDN interfaces 2 Recommendation Q.1111 (03/93) 3.2 Figure 2 shows the situation where an ISDN exists and the MSSC has an interface to it. Interworking with the PSTN is achieved via the

28、 ISDN. Interworking with PDNs may be by direct interface with the PDN or via the ISDN, as in the cases of the PSTN. A direct interface will be required for interworking with the telex network. SES In this scenario interworking with the ISDN supports speech, 3.1 kHz audio and data services as indicat

29、ed in 2.2.1. Other data services as indicated in 2.2.2 and 2.2.3 may require interworking with PDNs. I I CES MSSC FIGURE 2/Q.1111 Interim interworking scenario with interfaces to ISDN and other fixed networks 3.3 In the fully integrated interworking scenario the MSSC interfaces only to the ISDN. Thi

30、s is the preferred scenario and is illustrated in Figure 3. Interworking with the PSTN and the PDNs is achieved via the ISDN interface. However, interworking with the telex network may require a direct interface between the MSSC and the telex network. In this scenario also, data services as indicate

31、d in 2.2.2 and 2.2.3 are converted to formats which correspond to bearer services in the ISDN. The MSSC may then contain adaptors with functions equivalent to those defined for the ISDN. y8 CES MSSC TEEX 11 155810-9Wd3 / o FIGURE 3/Q.1111 Interworking scenario with interface to ISDN only Recommendat

32、ion Q.1111 (W93) 3 ITU-T RECMN*Q*LLLL 93 48b259L 058b375 885 4 Connection interface requirements 4.1 General This subclause identifies the information that must be available at the interfaces between the ship earth station (SES) and the MSSC and between the MSSC and the fixed network, principally fo

33、r the connection of services identified in 4.3. 4.2 MSSC-network interface For ISDN connections ISUP should be used for message transfer. For non-ISDN or where ISUP is not available, TUP would be preferred. If information transport between MSSCs over the fixed network is required, it is suggested th

34、at the procedures of the SCCP are used. Detailed interworking procedures are defined in Recommendation Q. 1 1 12. 4.3 SES-MSSC interface Prior to and during call initiation the signalling channel functions may be provided by one or more common control channels. A signalling capability should always

35、be available during conversation in case it is needed for call clearing, call control, or for call management purposes. During a call the signalling channel may be multiplexed with the traffic channel at a lower bit rate so as to conserve radio channel capacity. The multiplexed signalling channel on

36、 TDM/TDMA/RA channels may be used for bearer services such as connectionless data services, or connection oriented data services not requiring the establishment of a traffic channel. The traffic channel should be used for bearer services such as: - speech; - circuit mode data services (including fac

37、simile); - packet mode data service; - voice band data services. 4.4 Terminal to ship earth station interface 4.4.1 Non-ISDN interface A configuration for non-ISDN terminals is shown in Figure 4. Digits may be entered either from telephone hand sets, or data terminals, which use Q.23 tone signalling

38、 formats. The signalling interface between the ship earth station and the terminais must also provide a means for detecting the hook-on/off condition. The line connection to the terminal from the ship earth station may use either analogue or digital techniques. The ship earth station must convert bo

39、th the signalling (digits and on/off-hook) information and the line connection format (analogue or digital) into the protocols used on the radio path. 4.4.2 ISDN interface A typical example of the type of interface required could be as shown in Figure 5. In this case the ship earth station needs to

40、provide a function equivalent to NT2 of the ISDN for termination of the ISDN basic access (see Recommendation 1.420). When CC No. 7 (ISUP) is used for interconnection at the MSSC, the coding of cai1 failure causes used on the satellite channels will be in accordance with Recommendation 4.93 1. 4 Rec

41、ommendation Q.1111 (03/93) Q.23 tone I 1 signalling FIGURE 4/Q. 1 1 1 1 SES signaliing interface for non-ISDN terminals SES I ISDN bask access Signailing on the radio path FIGURE 5/Q.1111 SES signalling interface for ISDN terminals 4.5 calling procedures 4.5.1 Ship-to-shore call a) Information eleme

42、nts on the radio path . The ship earth station should include the following information in the “access request” message: - - connection request; the CES address to which the request is being sent; - bearer capabilities; - - special user facilities. This will be followed by the “service address” mess

43、age, containing the called party address. In order to expedite the call Set-up, all digits (and other information) will be entered into the ship earth station terminal prior to the request to the MSSC to set up the call. special category indication such as priority, etc.; Recommendation Q.1111 (03/9

44、3) 5 ITU-T RECNN*Q*LLLL 93 = 4862591 0586377 658 b) Informution elements on thefixed getwork The MSSC in addition to the information provided. should also add the following where the signalling system supports it: - continuity indicator; - echo suppressor indicator; - satellite indicator. The call s

45、hould then be progressed by the MSSC in the normal manner, with the following indications being returned to the ship earth station upon receipt from the network: - called party answer; - failure cause indicator (information indicating the cause for the failure of an unsuccessful call attempt); - cle

46、aring signal. The answer signal, clearing signal or channel release signal, and called party address may be used by the ship earth station to generate charging information. On receipt of a message with a cause indicator, the ship earth station should generate the appropriate audible tones (see Recom

47、mendation Q.35), and/or visible message information if an ISDN terminal is used. c) Clearing of call If the ship earth station wishes to clear a call, the ship earth station terminal should generate a “channel release” message to the MSSC. The MSSC should forward this to the network to release conne

48、ctions in the ISDN. The MSSC should receive a “release complete” message from the fixed network. The MSSC should also deal with a “call release” message from the network. A “channel release” message should be forwarded to the ship earth station to clear the connection and a “release complete” messag

49、e should be generated to return to the network. Special facilities for “malicious call” detection needs further study. For ship originated calls normal clearback procedures should apply (see Recommendation Q. 1 18) when interworking with the PSTN with the supervision applied at the MSSC. Handling of suspendresume messages to and from the ISDN requires further study by INMARSAT. 4.5.2 Shore subscriber initiated call a) Deletion of country code In most cases the MSSC will not need the information contained in the S-digit of the country code 87s. In this situation the sequence of