JPS63290024A - Satellite communication system - Google Patents

Abstract

PURPOSE:To smoothly restart an operation after the restoration of a common signal line, and to elevate the operating efficiency of a system by making a terminal equipment regulate a call when the defective continuity state of the common signal line is detected by a line state monitoring means. CONSTITUTION:An earth station is provided with the line state monitoring means A and a call regulating means B, and the line state of the common signal line is monitored by the line state monitoring means A, and when the common signal line is decided to be impossible to conduct a signal, by this line state monitoring means A, the call from the terminal equipment is regulated by the call regulating means B. because a subsequent call request is not performed, the increase of the processing quantity of the earth station is suppressed, and a trouble that the system fells into an overcrowding is avoided beforehand. Thus, the earth station can be immediately and smoothly restart the operation without any special restarting procedure or the like after the restoration of the common signal line, and thus, the operating efficiency of the system can be elevated.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to improvement of a satellite communication system to which a demand assignment method is applied.

(Prior art) In recent years, voice and data transmission has been increasingly carried out using satellite communication systems, but satellite communication systems use the Briassign method in which fixed communication lines are allocated between each earth station in advance. There are two types: one that applies the method and one that applies the demand assignment method. Among these, the demand assignment method pools a certain number of satellite communication lines in common at each earth station, and each time a line allocation request is made from a terminal device connected to the earth station, a certain number of satellite communication lines are selected from among the above satellite communication lines. This system selects an available line and allocates this line to the terminal device, and dynamic line allocation allows efficient use of limited satellite communication lines. Further, this demand assignment method includes a centralized control method and a distributed control method. First of all, in the centralized control method, a central control station is installed as a superior station for each earth station to which terminal devices are connected, and this central control station controls the selection of available lines and the setting and release of lines to each earth station. This is to centralize allocation control. In contrast, in the distributed control method, each earth station has the same line allocation control function as the central control station in the centralized control method.
In this system, line allocation control is performed between a station requesting line allocation and its partner station.

By the way, in a satellite communication system that applies the demand assignment method, whether it is a centralized control method or a distributed control method, it is necessary to send and receive control information between the corresponding earth stations when performing line assignment control. There is a common signal line (C8C) for sending and receiving this control information.
This is done using a control communication line called a radio channel. For this reason,
For example, if the transmission quality of the common signal line deteriorates due to rainfall attenuation, which is a problem unique to satellite communications, it becomes impossible to smoothly exchange control information between each earth station, which slows down various processes at the earth station, and the processing load gradually increases. . When the state of the common signal line becomes non-conducting, the relevant earth station may selectively abandon processing in the waiting state after a certain period of time, or the terminal device or earth station that issued the line allocation request. The terminal is busy with an extremely large number of processes, such as processing a request to allocate a new line while also processing a notification that a call cannot be made to the terminal, and eventually falls into a state of congestion. Once this congestion occurs, the earth station in question cannot recover unless it is restarted, which is extremely undesirable as it requires a lot of time and effort to recover.

(Problems to be Solved by the Invention) As described above, in the conventional system, when the common signal line becomes inoperable, the amount of processing at each earth station increases and it is easy to fall into a congested state, making it difficult to recover smoothly. However, the present invention focuses on this point and prevents the earth station from falling into a congested state when the common signal line becomes inoperable. The objective is to provide a satellite communication system that can resume operation smoothly and improve the operational efficiency of the system.

[Structure of the Invention] <Means for Solving the Problems> According to the present invention, as shown in FIG. The state monitoring means A monitors the line state of the common signal line, and when the line state monitoring means A determines that the common signal line is not conductive, the call restriction means restricts the terminal device from making calls. It was designed to do this.

(Function) As a result, when the line condition of the common signal line deteriorates and becomes unable to conduct, the call restriction means 8 restricts each terminal from making a call, and no further call requests are made. Therefore, the increase in the amount of processing at the earth station is suppressed, and the problem of the system falling into a state of conflict is avoided. Therefore, the earth station can resume operation immediately and smoothly without restarting after the common signal line is turned on, thereby increasing the operational efficiency of the system.

(Embodiment) FIG. 2 is a schematic configuration diagram of a satellite communication system in an embodiment of the present invention. This system t adopts a distributed control method, and includes a plurality of earth stations 10.10 each connected with a plurality of terminal devices 20, and these earth stations 10.10.
A communication satellite (
(hereinafter referred to as the Space Station). Among these, the earth station 10゜10 has an exchange 11 that exchanges and connects the terminal device 20, a line control device 12, and a modem (M/D) that modulates and demodulates voice or data output from the terminal device 20.
) 13 and a transmitting/receiving section 14 that transmits and receives data via an antenna 15.

As shown in FIG. 3, the line control device 12 includes an input/output control section 21 that controls the input and output of signals to and from the exchange 11 and the modem 13, and a terminal device 20 that handles call processing when an incoming call occurs, captures the communication line, The main control unit 22 performs various controls such as selection of a vacant line and acquisition of a line when a line allocation request is generated, and further includes a supervisory control unit 23 as a third control unit. The monitoring control unit 23 determines the line status of the common communication return line by monitoring whether or not expected control information arrives from the partner earth station within a certain period of time, for example, and determines that the common signal line is not conductive. In this case, a call restriction signal is output to the exchange 11Ei11.

Because of this configuration, each earth station 1
The line control device 12 of 0.10 executes various controls by the main control section 22 in response to requests for outgoing and incoming calls generated from the terminal device 20 or other earth stations. At the same time, the monitor control unit 24 monitors reception of the common signal line.

Now, in this state, if the quality of the common signal line deteriorates due to rain attenuation and the expected information is no longer received within a certain period of time, the monitoring control section 23 of the line control device 12 performs step 5a and the like as shown in FIG. This is detected in step 5b and determined to be a conduction failure in the common signal line, and a call restriction signal is output to the exchange [11] in step 5c. Here, as shown in FIG. 4, between the line control device 12 and the exchange 11 are audio signal lines 16 and 17 for transmitting audio signals;
SSI! 18 and an SR line 19, of which the SS line 18 and one SR line are signal lines for transmitting line connection and disconnection. Therefore, the call restriction signal outputted from the supervisory control section 23 is
If the signal is to set the R line 19 to the ground level, the output of the call restriction signal will put each trunk of the exchange 11 in the same state as in use, and even if the terminal device 20 makes a call in this state, it will not be accepted. A busy signal is sent back to the terminal device 20 without any delay. Therefore, from now on, from the exchange 11 to the line control device 1.
No new processing request such as a call request is sent to 2, and the line control device 12 and the exchange 11 are separated. Therefore, the amount of processing in the main control section 22 of the line control device 12 is gradually reduced, and as a result, the problem of falling into a congestion state is avoided.

In addition, in this call restriction state, the supervisory control unit 23
In step 5d of the figure, we are celebrating the recovery of the common signal line.
In this state, when the rain attenuation is reduced and the quality of the common signal line is restored, the process moves to step 5e, where a call restriction release signal is sent to the exchange 11, that is, the SR line 19 is returned to the "H" level state. Outputs a signal for As a result, each trunk of the exchange 11 returns to the standby state, and the terminal device 20 is then able to make calls.

As described above, in this embodiment, even if the quality of the common signal line deteriorates due to rain attenuation or the like and the common signal line becomes unable to conduct, the line control device 12 connects the switch to the exchange 11 at the point when the common signal line becomes unable to conduct. Since the SR line is set to the earth and calls are restricted to the terminal device 20, the processing amount of the line control I table device 2 is reduced thereafter, and as a result, the earth station 1
There is no need to worry about 0 falling into a state of conflict. Therefore, the earth station can immediately start normal processing after the common signal line is restored, thereby increasing the operational efficiency of the system. Further, according to this embodiment, the call control of the terminal device can be carried out by an extremely simple means of simply setting the SR line of the exchange to ground.

Note that the present invention is not limited to the above embodiments. For example, although the above embodiment has been described using a decentralized system as an example, it may also be applied to a centralized control system. If this centralized control method is applicable, in the case of a random access method in which information is sent randomly from each sub-side earth station to the coarse-side central control station, from each earth station to the central control station after the common signal line is restored. It is possible to limit the required processing ω, thereby suppressing a rapid increase in the amount of processing at the central control station and avoiding the problem of falling into a state of conflict. In addition, the structure of the means for monitoring the line state of the common signal line, the structure of the call restriction means, etc. can be modified in various ways without departing from the gist of the present invention.

[Effects of the Invention] As detailed above, according to the present invention, the earth station is provided with a line condition monitoring means and a call regulation means, and the line condition of the common signal line is monitored by the line condition monitoring means. When it is determined that the common signal line is not conductive by the line state monitoring means, the call restriction means restricts the terminal device from making a call, so that the common signal line is no longer conductive. It is possible to prevent the earth station from falling into a congestion state in the event of a common signal line being restored, thereby providing a satellite communication system that can resume operation smoothly after the common signal line is restored and improve the operational efficiency of the system. .

[Brief explanation of the drawing]

FIG. 1 is a functional block diagram showing the configuration of a satellite communication system according to the present invention, FIG. 2 is a schematic configuration diagram of a satellite communication system according to an embodiment of the present invention, and FIG. 3 is a configuration of a line control device of the same system. FIG. 4 is a circuit block diagram showing the connection configuration between the circulation line control I device and the exchange, and FIG. 5 is a flowchart showing the control procedure and control contents of the supervisory control unit. A...Line status monitoring means, B...Call regulation means, 1
0...Earth station, 11...Exchange meaning, 12...Line υ
Control device, 13...Modem, 14...Transmission/reception unit, 1
5... Antenna, 16.17... Audio signal line, 18
...SS line, 19...5R1il, 20...terminal device, 21...input/output control unit, 22...main control unit,
23... Supervisory control unit, 30... Space station, 40...
Satellite communication line. 30th t 4D

Claims (1)

[Claims] A plurality of earth stations are connected via a communication satellite, and control information is exchanged between each earth station via a common signal line each time a line allocation request is generated from a terminal device connected to the earth station. In a satellite communication system applying a demand assignment method that allocates free lines to terminal devices, the earth station includes a line condition monitoring means for monitoring the condition of the common signal line, and a line condition monitoring means for controlling the continuity of the common signal line. 1. A satellite communication system comprising: call restriction means for controlling the terminal device to make calls when a defective state is detected.