1、INTERNATIONAL TELECOMMUNICATION UNION)45G134 1 TELECOMMUNICATIONSTANDARDIZATION SECTOROF ITU).4%27/2+).G0G07)4(G0G03!4%,)4%-/“),%G0G03934%-3).4%27/2+).G0G0“%47%.3).!,).G0G03934%-G0G02 G0G0!.$).-!23!4G0G034!.$!2$G0G0!G0G03934%-)45G134G0G0RecommendationG0G01 (Extract from the “LUEG0“OOK)NOTES1 ITU-T R
2、ecommendation Q.1102 was published in Fascicle VI.14 of the Blue Book. This file is an extract fromthe Blue Book. While the presentation and layout of the text might be slightly different from the Blue Book version, thecontents of the file are identical to the Blue Book version and copyright conditi
3、ons remain unchanged (see below).2 In this Recommendation, the expression “Administration” is used for conciseness to indicate both atelecommunication administration and a recognized operating agency. ITU 1988, 1993All rights reserved. No part of this publication may be reproduced or utilized in any
4、 form or by any means, electronic ormechanical, including photocopying and microfilm, without permission in writing from the ITU.Fascicle VI.14 - Rec. Q.1102 1Recommendation Q.1102Fascicle VI.14 - Rec. Q.1102INTERWORKING BETWEEN SIGNALLING SYSTEM R2AND INMARSAT STANDARD A SYSTEM1 IntroductionIt is n
5、ecessary to specify the interworking of Signalling System R2 and the signalling systems used in theINMARSAT Standard A system. This is because:a) it may be desirable that a Maritime Satellite Switching Centre (MSSC)1)be connected to an internationalswitching centre (ISC) by employing System R2 on th
6、e circuits between the MSSC and the ISC;b) the signalling system used in the Maritime Mobile-Satellite Service will be different from System R2.Therefore it would be necessary to establish rules by which signalling events in one system may berelated to corresponding events in the other system.It is
7、desirable that the interworking be such that the full capability of both System R2 and the maritime satellitesignalling system be utilized.This Recommendation considers only automatic interworking between the MSSC and an ISC utilizing eitherthe analogue or digital versions of System R2 signalling.Fo
8、r description of the INMARSAT Standard A signalling system, see annex A to Recommendation Q.1101.2 Calls from Signalling System R2 to the maritime satellite system (see figure 1/Q.1102)2.1 The ISC sends the seizing signal followed by either of the following sequences of address signals:2.1.1 Signal
9、I-10 or a language digit when the country code 87S is not required for routing in the MSSC. At theMSSC this signal should be acknowledged by the signal A-5 in order to obtain the calling subscribers category (GroupII signal). The Group II signal is acknowledged at the MSSC by A-1. The ISC then conti
10、nues to send further addresssignals which are acknowledged in compelled cycles with A-1 at the MSSC.2.1.2 The country code indicator when the country code 87S is required for routing in the MSSC. One of thefollowing signals can be used as country code indicator:- Signal I-11 when the MSSC has to ins
11、ert an outgoing half-echo suppressor;- Signal I-14 when an outgoing half-echo suppressor has been inserted.At the MSSC this signal should be acknowledged by the signal A-5 in order to obtain the calling subscriberscategory (Group II signal). The Group II signal is acknowledged at the MSSC by A-1. Th
12、e ISC continues to send thecountry code digits and further address signals which are acknowledged in compelled cycles with A-1 at the MSSC._1)For definition, see Recommendation Q.1101.2 Fascicle VI.14 - Rec. Q.11022.1.3 Any numerical (or address) signal of the above sequences may be acknowledged by
13、the signals A-3 or A-4:- A-4 if congestion or abnormal release occurs in the MSSC;- A-3 may, for example, be used in order to indicate to the ISC barring of unauthorized group calls. Suchcalls are identified from the first digit following the discriminating digit. The appropriate Group B signalwould
14、 in this case be B-2.This use of A-3 is only possible if analysis of the discriminating (or language) digit and the first digit ofthe subscriber number takes place before the whole number has been received by the MSSC. If this is notthe case, the procedure of 2.2 should be followed.2.2 When the last
15、 address signal has been received at the MSSC, and number analysis has been completed, oneof the following events leading to unsuccessful call completion may occur:- The called ship earth station is excluded from participating in the system, the number of the calledterminal has been changed or the r
16、eceived number is an unauthorized group call number (see also 2.1.3above). In these cases the MSSC shall send the A-3 signal followed by B-2 after the Group II signal hasbeen received from the ISC.- The NCS/MSSC is out of service. In this case the A-4 signal is sent, or the A-3 signal followed by B-
17、4after receipt of the Group II signal.- The received number does not belong to any ship earth station. In this case the A-3 signal is sentfollowed by B-5 after receipt of the Group II signal.2.3 If the received number is valid, the MSSC sends A-1 as an acknowledgement to the last digit (or the end-o
18、f-pulsing signal I-15) in order to suspend the compelled signalling.2.4 The MSSC sends a Request-for-Assignment message to the Network Coordination Station (NCS) in order toobtain a satellite channel (see Annex A to Recommendation Q.1101).“If no reply to this request is received within 4 seconds (or
19、 8 seconds if the request is repeated by the MSSC)or, if a congestion message is received from the NCS, the MSSC sends the pulsed A-4 signal or the A-3 signalfollowed by B-4 after receipt of the Group II signal.“If a Ship busy message is received, the MSSC sends the pulsed A-3 signal followed by the
20、 B-3 signal afterrecognition of the forward Group II signal.If an Assignment message is received from the NCS, the MSSC connects the continuity tone on the assignedsatellite channel. If a continuity tone is received from the ship earth station within 10 seconds, the MSSC sends thepulsed A-3 signal f
21、ollowed by the B-6 signal after recognition of the forward Group II signal.The continuity check may fail in two ways:- no radio carrier is received from the ship earth station within 10 seconds (e.g. the ship is outside thesatellite coverage area), or- a radio carrier but no continuity tone is recei
22、ved from the ship earth station within 10 seconds.The MSSC sends the pulsed A-3 signal followed by B-2 or B-8 respectively after recognition of the forwardGroup II signal.2.5 When the MSSC detects the answer signal from the ship earth station, the MSSC must send the answer signalas soon as possible
23、to the ISC.2.6 When the MSSC detects the clear forward from the terrestrial network, the terrestrial circuit and the satellitelink will clear down according to their respective specifications. If, however, switching at the MSSC is achieved bydirect frequency selection then it will be necessary to de
24、lay the release-guard on the terrestrial link until the satellitelink is idle.2.7 The MSSC should send the clear-back signal into the terrestrial network when clear-back is detected on thesatellite link. The satellite link will be released so that the provisions of Recommendation Q.118 do not apply
25、for thispart of the connection.2.8 For the SDL description of incoming Signalling System R2, see Recommendation Q.616 1.Fascicle VI.14 - Rec. Q.1102 32.9 For the SDL description of interworking between incoming Signalling System R2 and the outgoingINMARSAT signalling system see Annex A.2.10 For SDL
26、description of outgoing INMARSAT signalling system, see Annex C to Recommendation Q.1101.3 Calls from the maritime satellite system to Signalling System R2 (see figure 2/Q.1102)3.1 The MSSC should not seize a terrestrial circuit before each of the following conditions have been met:- the satellite c
27、hannel has been assigned;- the continuity of the satellite channel has been verified;- all digits necessary for routing decisions by the MSSC have been received.3.2 The first register signal to be sent by the MSSC is:- the discriminating digit I-10 if the call is destined for a country whose ISC has
28、 direct connections to theMSSC;- the country code indicator I-14 if the call is destined for another country and the incoming half-echosuppressor is to be inserted at a later ISC;- the country code indicator I-12 if the call is destined for another country and the incoming half-echosuppressor can on
29、ly be inserted at the MSSC.3.3 The MSSC must respond to Group A or Group B signals in accordance with current Signalling System R2specifications.The following special requirements should however be taken into account:- If the signal A-14 is received from the ISC, the MSSC must either forward I-14 in
30、 order to indicate thatan incoming half-echo suppressor is required, or forward the next address signal where the MSSC hasalready inserted an incoming half-echo suppressor.- If the signal A-3 or A-5 is received from the ISC, the MSSC should send the II-7 signal (for the timebeing no other category s
31、ignal would be required).The signals A-3, A-5 and A-14 may be received at any time during interregister signalling sequence.If the signal A-11 is received from the ISC, the MSSC should send:- I-14 to indicate that an incoming half-echo suppressor is required, or- I-12 where the MSSC has already inse
32、rted an incoming half-echo suppressor.If the signal A-12 is received, the next signal shall be the discriminating digit (I-10).The MSSC should be capable of responding to signal A-13 with the signal A-14 in order to indicate that asatellite link is included (see Recommendation Q.480 2).3.4 The end o
33、f pulsing signal I-15 should be sent by the MSSC, if required and requested, if the equivalent end-of-pulsing signal is received from the ship earth station.3.5 The tones sent by the MSSC to the ship earth station in response to Group B signals received from theterrestrial network should comply with
34、 Recommendation Q.474 3. The characteristics of the tones are given inRecommendation Q.1101.4 Fascicle VI.14 - Rec. Q.11023.6 Time-out supervision on the answer signal at the MSSC should comply with the provisions given inRecommendation Q.118, 4.3.1.3.7 If the MSSC receives a clear-back signal from
35、the terrestrial network, the time-out ofRecommendation Q.118, 4.3.2 shall be started. The satellite and terrestrial links will be cleared either by the shipearth station or by expiry of the 1-2 minute time-out.3.8 When the MSSC detects a release condition on the satellite link, the terrestrial conne
36、ction should be clearedforward as soon as possible.3.9 For the SDL description of outgoing System R2, see Recommendation Q.626 4.3.10 The SDL description of the interworking between incoming INMARSAT Standard A signalling system andoutgoing System R2 is given in Annex B.3.11 For the SDL description
37、of incoming INMARSAT Standard A signalling system, see Annex B toRecommendation Q.1101.ANNEX A(to Recommendation Q.1102)Logic procedures for interworking of Signalling System R2to the INMARSAT Standard A signalling systemFascicle VI.14 - Rec. Q.1102 5FIGURE A-2/Q.1102(Reserved for future notes)6 Fas
38、cicle VI.14 - Rec. Q.1102 Fascicle VI.14 - Rec. Q.1102 7ANNEX B(to Recommendation Q.1102)Logic procedures for interworking of the INMARSAT Standard Asignalling system to Signalling System R2Supervisory timers for interworking of the INMARSAT Standard A signalling system to Signalling System R2t1= 2-
39、4 minutes Recommendation Q.118, 4.3.1t2= 1-2 minutes Recommendation Q.118, 4.3.2FIGURE B-2/Q.1102Notes to interworking of the INMARSAT Standard Asignalling system to Signalling System R28 Fascicle VI.14 - Rec. Q.1102 Fascicle VI.14 - Rec. Q.1102 9 10 Fascicle VI.14 - Rec. Q.1102References1 CCITT Rec
40、ommendation Logic procedures for incoming Signalling System R2, Vol. VI, Rec. Q.616.2 CCITT Recommendation Miscellaneous procedures, Vol. VI, Rec. Q.480.3 CCITT Recommendation Use of group B signals, Vol. VI, Rec. Q.474.4 CCITT Recommendation Logic procedures for outgoing Signalling System R2, Vol. VI, Rec. Q.626.
