JPH0761177B2 - Wide area mobile communication system - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a wide area mobile communication system, and more particularly to a wide area mobile communication system in which a car telephone system can be shared by both ground stations and space satellite stations. Regarding

[Background of the Invention]

In general, a wide area wireless communication system installed in a vehicle is provided with a plurality of ground stations with a predetermined interval in order to increase the subscriber capacity, and a zone (communicable area) of the plurality of ground stations is used to move the vehicle. A so-called small zone system that enables simultaneous communication is adopted.

However, it is economically difficult to install a large number of ground base stations, and it is not preferable to install a ground station even in an area where automobile traffic is low. Especially, in the mountainous area, since the radio wave is blocked and the communication distance of the radio wave is limited, more ground stations are required. In addition, the communication system is VO, a magazine published in January 1981.
L64, No. 1, pp. 7-29.

[Object of the Invention]

An object of the present invention is to eliminate the above-mentioned problems of the prior art, and in particular to provide a wide area mobile communication system capable of car telephone communication without providing more ground stations.

[Outline of Invention]

In order to achieve the above-mentioned object, the wide area mobile communication system according to the present invention provides a space communication line via a space satellite base station in addition to a ground communication line via a ground base station. It is characterized by carrying out communication.

Example of Invention

An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a diagram showing an outline of a wide area mobile communication system according to an embodiment of the present invention.

The communication system according to the present embodiment includes a ground base station 2a for ground communication with a moving mobile body, for example, an automobile 1.
2b, a vehicle 1 or a space satellite base station 3 for performing space communication with the vehicle 1 when the vehicle 1 moves outside the small dunes of the ground base stations 2a and 2b, and space station bases 4a and 4b, and the ground base station 2a. And 2b or the space satellite base station 3, and the ground communication network 5a for communicating with the other station communicating with the automobile 1 and
With 5b. When the vehicle 1 is located in the radio zone of the ground base station 2a (left position in the figure), the vehicle 1 communicates with the other station via the ground base station 2a and the ground communication network 5a. If 1 is located outside the radio zone of the ground base stations 2a and 2b (center position in the figure), the vehicle 1
Communicates with the other station via the space satellite base station 3 and the space base 4a or 4b by the ground communication network 5a or 5b.

FIG. 2 is a block diagram of the mobile communication device 11 mounted on the automobile 1 which enables communication by selecting the ground base station or the space satellite base station as described above.

This mobile communication device 11 includes an antenna 10 for transmitting and receiving radio waves to and from a ground base station or a space satellite base station, and the antenna 10.
From the signal received from the antenna duplexer 20 and the antenna 10 for sharing 10 with the transmission 30 and the receiver 40 described later,
A multi-channel receiver 40 for receiving a required radio signal (channel) by a high frequency signal from a frequency synthesizer 50, and an A / D converter 60 for converting the detection output of the intermediate frequency stage received by the receiver 40 into a digital signal. And a data receiver 70 that detects the received control signal from the base station.
And a microcomputer computer 90 that receives the output signals of the A / D converter 60 and controls the communication line from the base station.
And a telephone 100. In addition, this device uses the frequency of the frequency synthesizer 50 to transmit the transmission signal from the telephone 100.
Multi-channel transmitter 30 for converting to wireless signal to be transmitted
And a data transmitter 80 that creates the control signal to be transmitted.

The operation of this mobile communication device will be described below with reference to the operation flow charts of FIGS. 2 and 3.

The communication device shown in FIG. 2 receives radio waves from the ground base stations 2a and 2b via the antenna 10 and the duplexer 20 by the multi-channel receiver 40, and receives the control signal and the detection output of the reception signal as data. To the microcomputer 90 via the machine 70 and the AD converter 60. The computer 90
As shown in FIG. 3, the terrestrial control channel level for the terrestrial base station 2a or 2b input through the A / D converter 60 is detected, and the level is judged to determine the terrestrial base station 2a with the strongest radio wave. Or if 2b is selected and communication is possible, the ground station specifies a free channel of the ground station communication channel, and the frequency synthesizer 50 sets the radio signal frequency of the multichannel transmitter 30 to the frequency at which the communication with the ground station is performed. Then, the communication with the ground base station 2a or 2b is started.

When the channel level received from the ground station is lower than a predetermined level and communication with the ground is impossible, the microcomputer 90 causes the frequency synthesizer 50 to change the radio signal frequency of the multi-channel transmitter 30 to a space satellite. The frequency is set via the base station 3, and thereafter communication with the space station is started by the same method as in the case of via the ground station.
The multi-channel receiver 40 is set so that the ground station control channel can always be received by the frequency synthesizer 50 during standby. Therefore, when the automobile 1 moves after the call ends and enters the radio wave zone of the ground base station 2b, the microcomputer 90 sets the radio transmission frequency again for the ground station and communicates with the ground station.

Next, the supplement of the communication channels of the ground station and the space station by the microcomputer 90 in the above embodiment will be described with reference to FIG. FIG. 4 shows an example of channels assigned to ground stations and space stations.

The supplement (detection) of the channel of the ground station of the micro computer 90 described above is as follows: first, it is a level (electric field strength) at which communication is possible by scanning the ground channel communication channel group, and whether the channel is vacant. If it is detected, and it is vacant and is at an appropriate level, the ground station control channel group is corrected and communication with the ground station is performed. If you cannot communicate with this ground station, for example, if the level is low or there is no empty channel, then scan the control channel for the space station and if there is an empty channel, use the control channel via the space satellite base station. Make a call using the specified space station call channel. If the cost burden on the user changes between the case of passing through a ground station or a space station, the mobile communication device may be provided with a user guidance and a cost display function indicating that the user will go through a space station or a ground station. .

〔The invention's effect〕

As described above, according to the present invention, the communication with the space satellite base station is switched according to the channel level state of the ground base station, so that the communication can be performed by the mobile body at any place.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an embodiment of a wide area mobile communication system according to the present invention, and FIG. 2 is a diagram showing an embodiment of the mobile communication device shown in FIG. FIG. 3 is a flow chart showing the principle of selecting a ground station satellite station using the microcomputer of FIG. 2, and FIG. 4 shows an example of a wireless channel allocation diagram according to the present invention. 1 ... Car, 2a, 2b ... Ground base station, 3 ... Space satellite base station, 4a, 4b ... Space base station, 5a, 5b ... Ground communication network, 20 ... Antenna duplexer, 30 ... Multi-channel transmitter, 40 Multi-channel receiver, 50 Frequency synthesizer, 60 A / D converter, 70,80 Data transmitter and receiver, 90 Microcomputer, 10
0 ... phone.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location 7605-5K 109 H

Claims (1)

[Claims] 1. In a wide area mobile communication system for communicating between a mobile body moving in a wide area and a ground communication network, a first communication line for communicating with the mobile body via the ground communication network and a space line. And a second communication line for directly communicating with the terrestrial communication network and a mobile unit, and if the second communication line cannot communicate, the communication is performed via the first communication line. Wide area mobile communication system.