1、198 The CCIR, CCIR VOLUME*VIII 90 4855232 O533469 2 Rec. 586-1 RECOMMENDATION 586-1 * AUTOMATED VHF/UHF MARITIME MOBILE TELEPHONE SYSTEM (Question 23/8) (1982-1986) CONSIDERING (a) the international maritime mobile service and increase the efficient use of radio channels; (b) (c) facsimile and data;
2、 (d) (e) over the radio path and can provide for expansion to include other services; (f) that an automated VHF/UHF maritime mobile telephone service would expedite the handling of traffic in that there is an urgent need for such a service; that a system providing such a service could also allow for
3、 the transmission of, for example, telegraphy, athat international standardization is of great importance in the maritime mobile service; that the selective-calling system described in Recommendation 493 can form the basis for the signalling Recommendation No. 312 of the World Administrative Radio C
4、onference (Geneva, 1979), UNANIMOUSLY RECOMMENDS 1. that the automated VHF/UHF maritime mobile telephone system, should be in accordance with either of the two configurations described in Annex I depending on channel availability, and geographical and other considerations; 2. that the signalling pro
5、cedures to be used over the radio path should be in accordance with Annex II; 3. that the signalling messages to be transmitted over the radio path should be in accordance with Annex III. Note - Annexes IV and V provide supplementary information relevant to the operation of the automated VHF/UHF mar
6、itime radiotelephone system. ANNEX I , SYSTEM DESCRIPTION 1. General 1.1 The two configurations described in this An,nex differ only in their method of use of the calling channels. The marlied idle channel (MIC) configuration is based on the assignment of non-shared channels to each coast station wh
7、ile the time division multiple access (TDMA) configuration is based on time sharing of a common calling channel by a number of coast stations. 1.2 Signalling procedures have been unified to the maximum extent feasible in order to minimize the additional cost for a ship station compatible with both c
8、onfigurations. Annex II to this Recommendation describes the signalling procedures in detail. * The Director, CCIR, is requested todraw this Recommendation to the attention of the CCIT. _ COPYRIGHT International Telecommunications Union/ITU RadiocommunicationsLicensed by Information Handling Service
9、sCCIR VOLUME*VIII 90 U 4855232 O533470 9 Rec. 586-1 199 1.3 The signalling messages, described in Annex III to this Recommendation, are compatible with the digital selective-calling system (Recommendation 493). 1.4 In the following, a coastal area is defined as the geographic area covered by one or
10、more coast stations controlled by a maritime switching centre (MSC). Note that the concept of a maritime switching centre does not preclude distributing the switching facilities at different locations. 2. Marked idle channel configuration This configuration has the following characteristics: 2.1 as
11、“calling/idle working channel” (see 4 2.7 and Note 1). Shore-to-ship calling should be carried out over a channel marked either as “calling channel” (see 0 2.4) or 2.2 Ship-to-shore calling should be carried out over a channel marked either as “idle working channel” (see 0 2.5) or as “calling/idle w
12、orking channel” (see. 2.7 and Note 1). 2.3 There is no need for the assignment of a dedicated frequency pair for a calling channel. However, administrations could provide for one or more dedicated calling frequencies, if this can be justified with respect to the number of available channels. 2.4 Whe
13、n at one coast station two or more channels are not in use for traffic at a given time: - one of these channels should be designated as the calling channel (for shore-to-ship calling) and should be marked with a unique “calling channel” signal M1; one or more of the remaining idle channels should be
14、 marked with a unique “idle working channe” signal M2. The number of idle working channels so marked is dependent on the expected number of ship-originated call attempts and the related probability of interference, etc., and should be determined by the administration for each coast station. 2.5 Idle
15、 channels not carrying the unique “idle working channel” marking signals would normally first be used for shore-originated traffic. 2.6 station are occupied. 2.7 “calling/idle working channel” signal M3 to allow for use for both shore-originated and ship-originated calling. 2.8 If all channels are o
16、ccupied for traffic, no marking signals are transmitted by that coast station. - The designated “calling channel” should not be used for traffic unless all other channels of the coast If, at any time, only one channel is not used for traffic, this channel may be marked with a unique 2.9 If, starting
17、 from the situation that all channels are occupied, one channel becomes free of traffic, this may then be marked as a “calling/idle working channel”. 2.10 If in addition to the “calling/idle working channel a second channel becomes available, then the former channel should be marked (from that momen
18、t) with the “calling channel” marking signal. The second channel will then carry the “idle working channel” marking signal. 2.11 The marking signals should contain the coast station identification in accordance with Annex III to this Recommendation. Since it is possible that more than one channel co
19、uld be marked simultaneously with an “idle working channel” signal, ships should be provided with some means to randomize the selection of one of these idle channels for the call Set-up procedure. 2.13 Marking signals sent on an idle working channel should be transmitted with reduced working power.
20、Marking signals on the calling channel may also be sent at reduced power. However, calling sequences During the on-hook condition the ship station may lock on a channel marked either “calling channel or 2.12 and signalling sequences should be sent at full working power. 2.14 “calling/idle working ch
21、annel”. I /- COPYRIGHT International Telecommunications Union/ITU RadiocommunicationsLicensed by Information Handling ServicesCCIR VOLUME*VIII 90 H 4855212 0511471 O H 200 Rec. 586-1 When the ship is within radio coverage of several coast stations, the selection of which “calling channel” will be lo
22、cked on may be based on signal quality measurements, such as field strength level or error-rate, In addition, provision should be made for manual or automatic selection of predetermined coast station identities by ship stations, e.g. coast stations of a particular nationality. 2.15 If a ship to coas
23、t station call attempt is unsuccessful, a second call attempt may be made after initiating a new search for an M2 or M3 marked working channel. After two unsuccessful call attempts the ship station should abandon the call and provide an unsuccessful call attempt indication to the ship subscriber. I
24、3. Time division multiple access configuration (TDMA) This configuration has the following characteristics: 3.1 Shore-to-ship and ship-to-shore calling should be carried out over a dedicated calling channel which is a particular frequency pair, which may be time-shared by a number of coast stations.
25、 3.2 The calling channel is marked with a unique “random access” signal M4 during the time periods it is available for ship-to-shore call initiation (see 3.4),. 3.3 In the shore-to-ship direction, coast stations within interference range of each other should coordinate their transmissions so that no
26、 overlap occurs. Such time-sharing may be either on the basis of pre-allocated time slots or on a demand basis. In the latter case, arrangements should be made to ensure that one high-traffic coast station does not lock out other participating coast stations for excessive periods of time. 3.4 In add
27、ition to time periods for shore station originated call attempts, time periods are provided on the calling channel to allow initiation of ship-originated calls using random access. During these periods the channel is marked with a unique “random access” marking signal. Each marking sequence should a
28、lso indicate the number of random access time slots still to follow in the particular random access period. 3.5 Ship-to-shore call attempts should be transmitted only during the random access periods. Transmissions should be in time slots which are referenced to the “random access” marking sequences
29、. To further enhance the channel capacity, ship stations should employ a means to randomize the choice of time slot following reception of a “random access” marking sequence, taking into account the number of time slots remaining (encoded in the marking sequence, see 0 3.4). 3.6 required between coa
30、st stations within interference range of each other. When coast stations are allocated individual random access periods, coordination of the time periods is When a random access period is common to a number of coast stations, coordination between those coast stations should be effected to ensure ful
31、l area coverage and non-interference of marking signals. 3.7 transmit its acknowledgement over the ship-to-shore frequency of the calling channel. Upon receipt of a properly addressed call attempt from a coast station, the ship station shall immediately 3.8 addressed to that ship station during its
32、subsequent calling period. 3.9 Upon receipt of a location registration call attempt from a ship station (during the random access period) the appropriate coast station shall immediately transmit its acknowledgement over the shore-to-ship frequency of the calling channel. Upon receipt of a call attem
33、pt from a ship station, the appropriate coast station transmits a call sequence 4. Channel supervision If the quality of a speech channel decreases below a threshold level during the conversation, either the connection may be interrupted or a procedure may be started to switch the call-in-progress t
34、o a satisfactory working channel controlled by the same maritime switching centre (MSC). Two methods of channel quality supervision are given in Annex V of this Recommendation. The choice of the method used by each coast station may be decided by each administration; however, ship stations should be
35、 provided with facilities to enable the pilot tone method to be used, unless they sail only in waters where the pilot. tone method is not used. - COPYRIGHT International Telecommunications Union/ITU RadiocommunicationsLicensed by Information Handling ServicesCCIR VOLUME*VIII 90 = 4855232 0531472 2 W
36、 Rec. 586-1 201 5. Location registration Location registration is defined as the procedure to be followed for the ship station identity to be entered in a ship location register at the controlling maritime switching centre (MSC). 5.1 To simplify the routing of calls in the shore-to-ship direction pr
37、ocedures are used to update the MSCs location register. An updating procedure should be started by the ship station when entering a new coastal area and when initially switching on a ship station. 5.2 Marked idle channel configuration 5.2.1 Location registration in the MIC configuration should take
38、place on a working channel. 5.2.2 If during the on-hook condition the ship station loses the calling channel it is locked to, it will search for another calling channel. If the new calling channel marking signal indicates that the calling channel belongs to a different coast station, then the ship s
39、tation may initiate a location registration procedure (see also Recommendation 587). 5.3 TDMA configuration 5.3.1 Location registration in the TDMA configuration takes place on the calling channel. 5.3.2 If during the on-hook condition the ship station loses a particular coast stations signal, it wi
40、ll search for another time slot. If the new coast station identification indicates that it is a different coast station, then the ship station may initiate a location registration procedure (see also Recommendation 587). 5.4 In both configurations: 5.4.1 Location registration is considered to be fin
41、alized after a confirmation by the new coast station. 5.4.2 If the ship does not receive a confirmation from the coast station, it repeats the transmission of the relevant signal. (In the MIC configuration the second trial should be made after initiating a new working channel search.) 5.4.3 If the s
42、hip has not received a confirmation after 2 successive trials, it should not make further trials to the coast station. In this case non-completion of the location registration procedure should be indicated on the ships equipment. 5.4.4 Administrations are urged to issue guidelines to avoid transmiss
43、ion of unnecessary location registration signals. 6. Polling Coast stations may be provided with facilities for polling. Polling is defined as the procedure by which an MSC can interrogate ships in order to verify whether they are still within radio coverage. Polling is done to keep track of ships a
44、lready registered in the service area, Before deleting a ship from the register, several polling attempts should have been unsuccessful. 6.1 All signals necessary for polling should be transmitted on calling channels. Note 1 - No. 4908 of the Radio Regulations prohibits the .use of devices for conti
45、nuous or repetitive calling or identification; No. 4910 prohibits the emission of any carrier wave between calls. Therefore, continuous or repetitive marking of idle channels should be limited to the minimum required for the satisfactory operation of the system. Administrations are requested to reco
46、nsider this matter in preparing for the next competent World Administrative Radio Conference. - _ 7 ,- , COPYRIGHT International Telecommunications Union/ITU RadiocommunicationsLicensed by Information Handling ServicesCCIR VOLUME*VIII 90 m 4855212 0511473 4 W 202 Rc. 586-1 ANNEX II SIGNALLING PROCED
47、URES 1. Introduction 1.1 Purpose The purpose of this part of the Recommendation is to describe the calling and signalling arrangements to be used over th radio path. The description uses sequence diagrams to show how signals are exchanged between a coast station and a ship station. In addition to th
48、e signalling over the radio path, interworking with the signalling over the public telephone network is necessary. Operation of the complete system is illustrated in Appendices I to VI (Note 1) using the specification and description language (SDL) developed by the CCIT. Appendix I provides a genera
49、l introduc- tion to SDL. Appendices II and III show logic procedures for land-originated calls at the maritime switching centre (MSC) and at the ship station, respectively. Appendices IV and V show logic procedures for ship-originated calls at the MSC and at the ship station, respectively. Appendix VI shows the procedure at the MSC for power level control and for switching call-in-progress. Procedures are defined for both TDMA and MIC configurations (see Annx I). The procedures are such that the differences are as small as possible so that ship stations m
