JPH06224830A - Satellite communication system - Google Patents

Abstract

PURPOSE:To enable a mobile station to easily recognize an idle circuit in a system which performs the communication between the mobile station and a base station by means of a communication satellite. CONSTITUTION:On-vehicle stations 11a-11n and a base station 12 have the display circuit 15. When each of stations 11a-11n tries to transmit the signals to the station 12, the station searches for an idle circuit from the circuit application states shown on its circuit 15. When an idle circuit is detected, the transmission of signals is started to the station 12. At the same time, the code of its own station and the code of a receiver station are also transmitted via a common satellite circuit. Each on-vehicle station and the station 12 receive the codes from the common satellite circuit and update the display of each circuit 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a satellite communication system for performing communication between a mobile station and a base station by a satellite line.

[0002]

2. Description of the Related Art FIG. 3 is a system configuration diagram showing a conventional satellite communication system disclosed in, for example, Japanese Patent Laid-Open No. 4-42626. In the figure, 1 is a ship which is a mobile body, 2 is a general telephone subscriber (terrestrial subscriber) on the ground, 3 is a communication satellite,
Reference numeral 4 is a coastal ground station corresponding to a base station connected to the ground subscriber 2 by a ground line 5, and 6 is a communication control ground station which is installed separately from the coastal ground station 4 and controls the use state of the satellite line. Reference numeral 10 denotes a mobile communication device mounted on the ship 1.

Next, the operation will be described. The ship 1, which is a moving body, communicates with a partner, for example, a ground subscriber 2 via a communication satellite 3 and a coast ground station 4. At that time, the communication control ground station 6 transmits a control signal to the ship 1 on each channel of the satellite line. The mobile communication device 10 of the ship 1 is
It has a cover area storage unit. In the cover area storage unit, a line channel from the communication satellite 3 that can receive radio waves favorably for each area is set. In addition, the ship 1 has a positioning unit for knowing the current position, and recognizes a line that can receive the current radio wave satisfactorily from the stored data of the cover area storage unit and the current position by the positioning unit.

When communication is desired from the ship 1, the mobile communication device 10 receives a control signal from the communication control ground station 6 on each available line. Then, a line with the best control signal reception state is selected, and a request wave is transmitted to the communication control ground station 6 using that line. When the communication control ground station 6 receives the request wave,
A transmission permission signal for instructing the communication timing determined based on the usage status and priority of the line is transmitted to the mobile communication device 10. At the same time, it also transmits a predetermined control signal to the coast ground station 4.

Upon receiving the transmission permission signal, the mobile communication device 10 of the ship 1 transmits the data to be transmitted to the communication satellite 3 at the timing designated by the transmission permission signal. Then, the transmission data relayed by the communication satellite 3 is
It is received by the coastal ground station 4 and is further sent to the ground subscriber 2 via the ground line 5.

As described above, the vessel 1 can select a communicable satellite line according to its current position based on the coverage area data. Therefore, the receiving state of all lines is confirmed and the line with the best receiving state is selected. Compared with the case of doing, the work of searching for a satellite line used for communication can be performed easily in a short time.

There is also a system in which communication between a vehicle-mounted station (mobile station) and a base station on the ground is performed via the communication satellite 3. In such a system, a line control station is provided separately from the base station. And the line control station
It is scheduled or pre Which vehicle station has to communicate with any base station. Therefore, the vehicle-mounted station must make an inquiry to the line control station in order to know the line status.

[0008]

Since the conventional satellite communication system is constructed as described above, the ship 1, which is a moving body, must store the cover area data. Further, since it is necessary to judge that the control signal from the communication control ground station 6 is received by a plurality of lines in the coverage area and the line with the best reception condition is selected, complicated processing must be executed during communication. There was a problem that it had to be. In addition to the coast ground station 4, a communication control ground station 6 is required. In a system consisting of an in-vehicle station and a base station, it is necessary to make an inquiry to the line control station in order to know the line status, and it is not possible to respond promptly if an unscheduled emergency communication is desired. There is a problem. In addition to the base station, a line control station is required.

The present invention has been made in order to solve the above problems, and even if the mobile station does not store the coverage area data, the communication control ground station and the line control station are included in the system. An object of the present invention is to obtain a satellite communication system that can easily start communication with a base station without the need of the above.

[0010]

A satellite communication system according to the present invention is a system for mobile communication using a communication satellite for relaying a signal between each mobile station and a base station. , There are a plurality of communication lines used for communication between the transmitting station and the receiving station and a common satellite line for transmitting control information from any transmitting station to each of the other stations. When the communication line usage status that is being held indicates that the communication line is idle, the code indicating its own station and the code indicating the receiving station are transmitted as control information to the common satellite line when It starts transmission using the communication line and updates the communication line utilization status of the own station using the control information received from the common satellite line.

A satellite communication system according to a second aspect of the present invention is a system for mobile communication using a communication satellite for relaying a signal between each mobile station and a base station,
There are multiple communication lines used for communication between the transmitting station and the receiving station and each pilot signal transmission line for transmitting pilot signals.Each mobile station transmits pilot signals when transmitting by the communication line. After confirming that it has been received, transmission using a communication line is started, and the base station sends a pilot signal to each mobile station in a number corresponding to the number of idle communication lines.

[0012]

The mobile station according to the first aspect of the invention can immediately ascertain the current vacancy of the line based on the communication line utilization status held therein. Therefore, the mobile station can immediately start transmission through the communication line when attempting to transmit.

Further, the mobile station according to the second aspect of the invention can immediately grasp the current vacancy of the line by the pilot signal managed by the base station. Therefore,
The mobile station can immediately start transmission on the communication line when it intends to transmit.

[0014]

EXAMPLES Example 1. An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, 3 is a communication satellite, 11
, 11n are in-vehicle stations for satellite communication (hereinafter referred to as in-vehicle stations) which are mobile stations, and 12 are in-vehicle stations 11 respectively.
, 11n are base stations that communicate with a, 11b, ..., 11n via the communication satellite 3. Further, 13a is an up line of a communication line for transmitting information transmitted from the vehicle-mounted station 11a, 13b is a down line for the up line 13a, 14a is an up line of a common satellite line for transmitting a predetermined code, and 14b is for the up line 14a. It is a downlink. 15 is each in-vehicle station 11
, 11n and a display circuit for displaying the utilization status of the satellite communication lines provided in the base station 12.

Next, the operation will be described. Each in-vehicle station 11
At the time of transmission, a, 11b, ..., 11n transmit codes indicating a transmitting station and a receiving station through a common satellite line. For example, when the vehicle-mounted station 11a tries to transmit to the base station 12, the vehicle-mounted station 11a transmits a code indicating its own station and a code indicating the base station 12 to the common satellite line. Then, it communicates with the base station 12 through the communication line.

Then, these codes are used for each on-board station 11
a, 11b, ..., 11n and the base station 12. The display circuit 15 of each vehicle-mounted station 11a, 11b, ..., 11n and the display circuit 15 of the base station 12 display the transmitting station and the receiving station which are currently communicating based on the received code. Further, when the communication with the base station 12 is completed, the vehicle-mounted station 11a transmits a notification to the common satellite line. Each in-vehicle station 11a, 11b, ..., 11n that received it
Stops the corresponding display on the display circuit 15.
In this way, in each on-vehicle station 11a, 11b, ..., 11n, it is possible to easily recognize how many free communication lines are available within the range of the number of lines allowed for this satellite communication system.

For example, when the vehicle-mounted station 11b tries to transmit to the base station 12, the base station 11b displays the display circuit 15 thereof.
Check the line usage status displayed in. Then, if it is found that the line exceeding the allowable range is used, the transmission is not started, and the display circuit 15 waits until the display shows that an idle line has occurred. On the other hand, if it is found that the allowable range has not been used, immediately after transmitting the code of the own station and the code of the base station 12 on the common satellite line, communication with the base station 12 is started by the idle communication line. To do.

Example 2. In the above embodiment, the common satellite line is used to display the current satellite communication line use status by the display circuit 15.
However, the pilot signal set for each in-vehicle station may be used. FIG. 2 is a system configuration diagram showing a configuration of a satellite communication system according to a second embodiment of the present invention based on such an idea.

In the figure, 16a, 16b, ..., 1
6n is each from the base station 12 to each in-vehicle station 11
a, 11b, ..., 11n, an uplink of a pilot signal line for transmitting a pilot signal transmitted to 1n, 1
7a, 17b, ..., 17n are uplink lines 16 respectively
, 16n are downlink lines, and 18 is a display circuit provided in each on-vehicle station 11a, 11b, ..., 11n for displaying pilot signal reception.

Next, the operation will be described. Base station 12
Informs each of the vehicle-mounted stations 11a, 11b, ..., 11n through the pilot signal line whether the base station can use the communication line. That is, the base station 12
The number of base stations 12 corresponding to the number of circuits not currently used among the circuits permitted for the satellite communication system.
To send a pilot signal to. The vehicle-mounted station receiving the pilot signal displays the fact on the display circuit 18.

Therefore, the base station receiving the pilot signal is ready to use the communication line. For example, when the vehicle-mounted station 11a tries to transmit to the base station 12, the display circuit 18 causes the pilot signal lines 16a and 17a to be transmitted.
Check to see if you are receiving a pilot signal. When the reception is confirmed, the vehicle-mounted station 11a communicates with the base station 12 through the communication line. At this time, since one communication line is newly used, the base station 12 stops sending the pilot signal to one of the base stations currently transmitting the pilot signal thereto.

When the vehicle-mounted station 11a has not received the pilot signal, the vehicle-mounted station 11a is in a standby state until it can receive the pilot signal.

[0023]

As described above, according to the first aspect of the invention, in the satellite communication system, each mobile station sends a specific code upon transmission, and the communication line utilization condition is determined in response to the reception of the specific code. Since it is configured to grasp, there is an effect that each mobile station can easily determine whether or not it can communicate with the base station without performing complicated determination and processing. In particular, since the mobile station can determine whether or not transmission is possible based on the information that the mobile station has, it is possible to quickly start communication even when an emergency occurs. It also has the effect of eliminating the need for communication control ground stations and circuit control stations.

According to the second aspect of the invention, the satellite communication system has a configuration in which each mobile station starts transmission based on the reception of a pilot signal indicating transmission permission from the base station at the time of transmission. There is an effect that each mobile station can easily determine whether or not it can communicate with the base station without performing complicated determination and processing. In particular, since the mobile station can immediately determine whether or not transmission is possible, it is possible to promptly start communication even when an emergency occurs. It also has the effect of eliminating the need for communication control ground stations and circuit control stations.

[Brief description of drawings]

FIG. 1 is a system configuration diagram showing a configuration of a satellite communication system according to an embodiment of the present invention.

FIG. 2 is a system configuration diagram showing a configuration of a satellite communication system according to another embodiment of the present invention.

FIG. 3 is a system configuration diagram showing a configuration of a conventional satellite communication system.

[Explanation of symbols]

 3 communication satellites 11a to 11n vehicle-mounted station (mobile station) 12 base station

Claims (2)

[Claims] 1. In a satellite communication system for mobile communication using a communication satellite that performs signal relay, a plurality of communication lines used for communication between a transmitting station and a receiving station and from any transmitting station to another There is a common satellite line that transmits control information to each station, and when performing transmission by the communication line, a code indicating the own station when the communication line usage status held indicates that the communication line is idle A code indicating a receiving station is transmitted to the common satellite line as control information, and then transmission using the communication line is started, and the communication line utilization status is updated using the control information received from the common satellite line. A satellite communication system, comprising: a plurality of mobile stations that perform communication; and a base station that communicates with each of the mobile stations via the communication line. 2. In a satellite communication system for mobile communication using a communication satellite that performs signal relay, a plurality of communication lines used for communication between a transmitting station and a receiving station and a pilot signal for transmitting a pilot signal. A plurality of mobile stations that have a transmission line and start transmission using the communication line after confirming that the pilot signal is received when transmitting by the communication line, and the mobile stations. And a base station that communicates via the communication line and sends a pilot signal to each of the mobile stations in a number corresponding to the number of idle communication lines.