JPH0645973A - Satellite communication system - Google Patents

Abstract

PURPOSE:To improve the availability of a satellite channel by returning a health check response signal by using a exclusive slot provided in the time slot column of a TDMA system. CONSTITUTION:A terminal station 1a receives a health check signal from a central station 3, and transmits the response signal to the central station 3 by using the exclusive slot provided in the random access time slot column which can be prevented from being colliding with a signal from the other terminal station 1n or the like. Therefore, at the central station 3, it is possible to speedily confirm the health check of the terminal station 1a, and cope with a line assignment request signal from the other terminal station 1n or the like. Thus, the availability of the satellite channel can be improved by preventing the useless collision of the signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a demand-division multiple access (hereinafter referred to as DAMA) system in which a central station allocates satellite communication to each terminal station, and the communication from each terminal station to the central station is time-division multiplexed. The present invention relates to a satellite communication system using a connection (hereinafter referred to as TDMA) system, and particularly to a health check of the terminal station.

[0002]

2. Description of the Related Art FIG. 4 is a block diagram showing a configuration of a conventional satellite communication system. In the figure, 1a to 1n are a plurality of terminal stations, and 2 is a communication terminal accommodated in each of these terminal stations 1a to 1n. 3 is each of these terminal stations 1
The central station assigns satellite lines between a to 1n, and 4 is its communication satellite. FIG. 5 is an explanatory diagram showing a TDMA time slot sequence in communication from the terminal stations 1a to 1n to the central station 3.
5 is an individual random access slot.

FIG. 6 is a timing chart showing a time relationship of signals transmitted and received between the terminal stations 1a and 1n and the central station 3 during a health check in the satellite communication system. In the figure, 6 is a health check signal sent from the central station 3 to the terminal station 1a, 7 is a health check response signal returned from the terminal station 1a to the central station 3, and 8 is a call sent from the terminal station 1n to the central station 3. It is a line allocation request signal in the processing signal.

Next, the operation will be described. The central station 3 checks the health of each of the terminal stations 1a to 1n at a predetermined cycle. Now, as shown in FIG.
It is assumed that the health check signal 6 is transmitted to. In response to the health check signal 6, the terminal station 1a sends back a health check response signal 7 to the central station 3 using the random access slot 5 shown in FIG. At this time,
At the same time, when the line allocation request signal 8 is transmitted from the other terminal station 1n to the central station 3 using the random access slot 5, the health check response signal 7 and the line allocation request signal 8 collide with each other, and As a result, the central station 3 cannot receive either signal.

In this way, when the health check response signal 7 from the terminal station 1a is lost, the central station 3 fails the terminal station 1a until it receives the health check response signal 7 from the terminal station 1a. Treat as a station. Therefore, even if the other terminal station 1n or the like sends a channel allocation request signal 8 to the central station 3 to the central station 3 while being treated as an abnormal station, the central station 3 operates the satellite channel. It cannot be assigned.

[0006]

Since the conventional satellite communication system is configured as described above, the confirmation of the health check of the terminal stations 1a to 1n is delayed due to the signal collision,
There is a problem that the efficiency of using the satellite line is reduced.

The present invention has been made in order to solve the above problems, and an object of the present invention is to obtain a satellite communication system with a high efficiency of use of satellite lines.

[0008]

In the satellite communication system according to the invention of claim 1, a dedicated slot is provided in the time slot sequence of the TDMA system, and the health check response signal is returned using this dedicated slot. is there.

Further, in the satellite communication system according to the invention of claim 2, when the health check signal is sent at the time of transmitting the call processing signal, the call processing signal is returned in the dedicated slot instead of the health check response signal. It is a thing.

[0010]

In the satellite communication system according to the invention of claim 1,
By returning the health check response signal using the dedicated slot provided in the time slot sequence of the TDMA method, a satellite communication system with high satellite line utilization efficiency is realized.

Further, in the satellite communication system according to the invention of claim 2, when a health check signal is sent at the time of transmitting the call processing signal, the call processing signal is replaced with the health check response signal in the dedicated slot. By returning the data, a satellite communication system capable of further improving the utilization efficiency of the satellite line is realized.

[0012]

EXAMPLES Example 1. An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a timing diagram showing an embodiment of the invention described in claim 1, and FIG. 2 is an explanatory diagram showing a TDMA time slot sequence in communication from a terminal station to a central station.

In the figure, 1a and 1n are terminal stations, 3 is a central station, 5 is a random access slot, 6 is a health check signal, 7 is a health check response signal, and 8 is a line allocation request signal as a call processing signal. 6 and FIG. 5 are the same as or equivalent to those of the related art denoted by the same reference numerals, and detailed description thereof will be omitted. In addition, in FIG.
Reference numeral 9 is a dedicated slot provided in the TDMA time slot sequence.

Since the configuration of the satellite communication system itself is the same as that of the conventional one shown in FIG. 4, its illustration and description are omitted.

Next, the operation will be described. The terminal station 1a, which has received the health check signal 6 from the central station 3 in the same manner as in the conventional case, uses the dedicated slot 9 provided in the random access time slot sequence to send the health check response signal 7 to the central station 3. To send. This dedicated slot 9 is a time slot in which only the terminal station (in this case, the terminal station 1a) that has received the health check signal 6 from the central station 3 can return the health check response signal 7, so that other terminals It does not collide with a signal from the station 1n or the like. Therefore, the central station 3 can promptly confirm the health check of the terminal station 1a, and then can smoothly respond to the line allocation request signal from another terminal station 1n or the like.

Example 2. Next, a second embodiment of the present invention will be described with reference to the drawings. FIG. 3 is a timing chart showing an embodiment of the invention described in claim 2. The same parts as those in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted. In the figure, 10 is a line assignment signal which the central station 3 sends to the terminal station 1a and the terminal station 1n of the communication partner in response to the line assignment request signal 8 from the terminal station 1a, and 11 is the terminal at the end of the call. This is a line release request signal in the call processing signal sent from the stations 1a and 1n to the central office 3.

Next, the operation will be described. When the terminal station 1a detects a call from any of the accommodated communication terminals 2, it sends out a line allocation request signal 8 to the central station 3. This line line allocation request signal 8 is a random access slot 5
Since it is sent to the central station 3 via the terminal, there is a possibility that another terminal station 1n or the like may collide with a signal transmitted to the central station 3. I cannot receive the signal. The terminal station 1a retransmits the line assignment request signal 8 to the central station 3 when the satellite line assignment is not obtained from the central station 3 even after a lapse of a predetermined time.

At that time, when the health check signal 6 is sent from the central station 3 to the terminal station 1a, the embodiment 1 shown in FIG.
In the satellite communication system of, the terminal station 1a has a dedicated slot 9
Health check response signal 7 using
The line allocation request signal 8 is retransmitted in the random access slot 5 again.

In the second embodiment, in order to eliminate the waste of separately sending back the health check response signal 7 and resending the line allocation request signal 8, the terminal station 1a, as shown in FIG. In place of the health check response signal 7 for the health check signal 6 from 3, the line allocation request signal 8 to be retransmitted is sent to the central station 3 using the dedicated slot 9. The dedicated slot 9 is provided in the time slot sequence of the TDMA system in order for each terminal station 1a to 1n to return the health check response signal 7, so that the line allocation request signal 8 is different from other signals. It does not cause a collision.

The central station 3 that has received the line allocation request signal 8 substituted for the health check response signal 7 is
It is determined that the result of the health check of a is normal, and in accordance with the transmitted line allocation request signal 8, an empty satellite line is selected and assigned to a communication partner, for example, a call with the terminal station 1n. , Line allocation signal 10
To notify the terminal stations 1a and 1n. The terminal stations 1a and 1n which have received the line allocation signal 10 enter into a call using the satellite line.

When the call ends, the terminal stations 1a and 1n send a line release request signal 11 to the central station 3 using the random access slot 5, and the central station 3 releases the satellite line used for the call. To do. Here, for example, when the line release request signal 11 transmitted from the terminal station 1n causes a collision and the health check signal 6 is transmitted from the central station 3 to the terminal station 1n almost at the same time, the terminal station 1n performs the health check. Instead of the health check response signal 7 for the signal, the line release request signal 11 is retransmitted using the dedicated slot 9. Upon receiving the line release request signal 11, the central station 3 determines that the terminal station 1n is normal and releases the satellite line.

If no request for line allocation or line release is made, the terminal station 1a (to 1n) responds to the health check signal 6 from the central station 3 with a health check response as in the first embodiment. Return signal 7.

[0023]

As described above, according to the invention of claim 1, since the health check response signal is configured to be returned using the dedicated slot provided in the time slot sequence of the TDMA system, the signal is not used. There is an effect that a satellite communication system can be obtained in which various collisions can be prevented and the utilization efficiency of satellite lines can be improved.

According to the invention of claim 2, when the health check signal is sent at the time of transmitting the call processing signal,
Since the call processing signal is returned in the dedicated slot instead of the health check response signal, there is an effect that the utilization efficiency of the satellite line can be further improved.

[Brief description of drawings]

FIG. 1 is a timing diagram showing a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a TDMA time slot sequence in communication from a terminal station to a central station in the present invention.

FIG. 3 is a timing diagram showing a second embodiment of the present invention.

FIG. 4 is a block diagram showing configurations of the present invention and a conventional satellite communication system.

FIG. 5 is an explanatory diagram showing a TDMA time slot sequence in communication from a terminal station to a central station in a conventional satellite communication system.

FIG. 6 is a timing diagram showing a health check operation in a conventional satellite communication system.

[Explanation of symbols]

 1a to 1n Terminal station 2 Communication terminal 3 Central station 6 Health check signal 7 Health check response signal 8 Call processing signal (line allocation request signal) 9 Dedicated slot 11 Call processing signal (line release request signal)

Claims (2)

[Claims] 1. A central station, comprising: a plurality of terminal stations; and a central station that selects a vacant satellite channel and allocates it to the terminal station in response to a satellite channel allocation request from the terminal station. In a satellite communication system in which an empty satellite circuit is allocated to a satellite circuit allocation request from a terminal station by a demand allocation multiple access method, and communication from the terminal station to the central station is performed by a random access time division multiple access method When a dedicated slot is provided in the time slot sequence of the time division multiple access system and the terminal station receives a health check signal from the central station, the terminal station returns a health check response signal for the health check signal using the dedicated slot. A satellite communication system characterized by. 2. When a health check signal is sent from the central station to the terminal station which was trying to transmit a call processing signal, the terminal station replaces the health check response signal with the dedicated call processing signal. The satellite communication system according to claim 1, wherein the satellite communication system uses a slot for the return.