JPH05206912A - Demand assignment multiple access satellite communication system - Google Patents

Abstract

PURPOSE:To permit a center station to periodically monitor a call state between satellite earth stations and to open a satellite-line so as to improve the use efficiency of the satellite line even if a call termination request signal cannot be detected. CONSTITUTION:When a call terminates, an open request signal is transmitted from DAMA subordinate control parts 21-2 and 22-2 in the satellite earth stations 2-1 and 2-2 through a control line 41. When the open request signal does not reach the center station 1 due to a trouble on satellite transmission, the center station 1 judges that the call is continued although the call between the satellite earth stations 2-1 and 2-2 is terminated. Thus, the DAMA main control part 12 of the center station 1 periodically inquires the call state between the satellite earth stations 2-1 and 2-2 to a monitor circuit 5. When it judges that the call from a result signal from a monitor circuit 13 is terminated, a call line 42 is opened and the satellite earth stations 2-1 and 2-2 are returned from the call state to a non-call state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a demand assignment multiple access satellite communication system using a satellite line.

[0002]

2. Description of the Related Art In a conventional demand assignment multiple access (DAMA) satellite communication system, after a center station allocates a satellite line to a satellite earth station, the satellite line is connected only by a request signal for opening the satellite earth station connection. It was open.

[0003]

In this conventional DAMA satellite communication system, since the satellite line is opened only by the connection earthing request signal from the satellite earth station, the satellite line is connected between the satellite earth stations. After allocating, when the center station misses the reception request signal from the satellite earth station,
The disadvantage is that the satellite line is not opened even though the call between the satellite earth stations has ended.

[0004]

The demand assignment multiple access satellite communication system of the present invention comprises a plurality of satellite earth stations,
A demand assignment multiple access satellite comprising a center station which, when receiving a communication request signal from the satellite earth station via the satellite line, controls the allocation of the satellite line to the satellite earth station via the satellite line. In the communication system, the center station has a monitoring means for monitoring the call termination state of the assigned satellite line at a predetermined cycle when communication is performed by a plurality of satellite lines to which the plurality of satellite earth stations are assigned. The monitoring means includes a satellite line opening means for opening the assigned satellite line when the call end state of the assigned satellite line is detected.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention.

In FIG. 1, the present embodiment has an artificial satellite 3 and
Satellite earth station 2-1 and 2-2 and satellite earth station 2-1 and 2-
The center station 1 which controls the allocation of the satellite line 4 to the satellite earth stations 2-1 and 2-2 when the signal of the communication request from the satellite line 2 is received via the satellite line 4 is provided. The station 1 receives a signal from the satellite line 4 and demodulates it, and also modulates an input signal and transmits it to the satellite line 4.
And a monitor circuit 13 for monitoring the communication state of the specified satellite circuit and transmitting a monitor result signal when receiving the monitor request signal of the specified satellite circuit in a predetermined cycle,
When the communication request signals from the satellite earth stations 2-1 and 2-2 are received via the radio device 11, the satellite line allocation control is performed, the call state of the satellite line 4 is monitored via the monitor circuit 13, and communication is performed. The satellite earth station 2 is configured to have a DAMA main control unit 2 for opening the satellite line used when the satellite earth station 2 is terminated.
Reference numeral -1 is a radio device 21-1 that transmits and receives signals to and from the satellite line 4 by modulation and demodulation, and a DA that performs connection control of the satellite line 4 by generation of a communication request signal and allocation from the center station 1.
The satellite earth station 2 is configured by including the MA slave control unit 21-2.
-2 similarly has the radio 22-1 and the DAMA slave control unit 22.
And -2.

Next, the operation of this embodiment will be described.

When the satellite earth station 2-1 and the satellite earth station 2-2 make a call, the DAMA slave control unit 2 of the satellite earth station 2-1 is used.
A connection request signal is sent from 1-1 to the center station 1 through the control line 41 via the wireless device 21-1. The DAMA main control unit 12 of the center station 1 receives this connection request via the wireless device 11, judges the state of the satellite earth station 2-2, and if the call is possible, sends the connection request to the satellite earth station through the control line 41. It is sent to the station 2-2.

DAMA slave control unit 22 of satellite earth station 2-2
-2, in response to the connection request, a response to the connection request is sent back to the center station 1 through the control line 41, and the DAMD main control unit 12 of the center station 1 sends a control line to the satellite earth stations 2-1 and 2-2. The communication line 42 is notified through 41.
Each DAMA slave control unit 21- of the satellite earth station 2-1 and 2-2
2, 22-2 switch to this call line 41,
A call is started between the satellite earth stations 2-1 and 2-2.

When the call ends, the satellite earth station 2-1 and 2-
The DAMA slave control units 21-2 and 22-2 of No. 2 send release request signals through the control line 41. However, if the release request signals do not reach the center station 1 due to satellite propagation problems, the satellite earth Although the call between the stations 2-1 and 2-2 has ended, the center station 1 determines that the call is continuing. In order to prevent this problem, the DAMA main control unit 12 of the center station 1 periodically inquires of the monitor circuit 5 about the communication state between the satellite earth stations 2-1 and 2-2. When it is determined that the call is finished from the result signal from, the call line 42 is opened,
Also, the satellite earth stations 2-1 and 2-2 are returned from the talking state to the no-call state.

[0012]

As described above, according to the present invention, when a plurality of satellite earth stations and signals for requesting communication from the satellite earth stations are received via the satellite lines, the satellite earth stations are controlled to allocate satellite lines. In a demand assignment multiple access satellite communication system that includes a center station that operates via a satellite line, the center station is predetermined when communication is performed by a plurality of satellite lines to which a plurality of satellite earth stations are allocated. By having a monitoring means for monitoring the call termination state of the assigned satellite circuit at a predetermined cycle, and a satellite circuit opening means for releasing the assigned satellite circuit when the call termination state of the assigned satellite circuit is detected by this monitoring means, Even if the center station receives the signal requesting to release the connection from the satellite earth station, the call status of the assigned satellite line can be monitored. An effect that can be.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

[Explanation of symbols]

 1 center station 2-1 and 2-2 satellite earth station 3 artificial satellite 4 satellite line 11 radio 12 DAMA main control unit 13 monitor circuit 21-1, 22-1 radio 21-2, 22-2 DAMA slave control unit 41 Control line 42 Call line

Claims (1)

[Claims] 1. A center for controlling allocation of satellite lines to a plurality of satellite earth stations and, when receiving a communication request signal from the satellite earth stations via a satellite line, controlling the satellite line allocation to the satellite earth station via the satellite line. In a demand assignment multiple access satellite communication system including a station, the center station allocates at a predetermined cycle when communication is performed on a plurality of satellite lines to which the plurality of satellite earth stations are allocated. A demand comprising: a monitoring means for monitoring a call termination state of the satellite line; and a satellite line releasing means for releasing the assignment satellite line when the call termination state of the assigned satellite line is detected by the monitoring means. Assignment multiple access satellite communication system.