JP2002064856A - Radio data transmission system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radio data transport system for readily responding to a wide operation area at low cost. SOLUTION: The system transmits a state of the position of a mobile station M from the mobile station M to a base station B via a leased radio network, and causes a display 13 of the base station B to display the position of the mobile station M. The above system comprises a public radio network constituted by a telephone terminal 3 and a mobile phone terminal 6 such that a radio network for exclusive use and a public radio network are switched to transmit a state of the position of the mobile station M from the mobile station M to the base station B, and the position is displayed on the display 13 even when the mobile station M goes outside a communication area of the base station B.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data transmission system between a plurality of mobile stations and a base station, and more particularly to a radio data transmission system in which the positions of the mobile stations are displayed and grasped by the base station. .

[0002]

2. Description of the Related Art In recent years, there has been known a so-called car navigation system which uses a positioning system such as a GPS to detect the position of a car, even during running, and to display the map on the map in the car to guide the running of the car. It has been used and the speed of its spread is phenomenal. Here, the GPS is a global positioning system (global positioning system), and the car navigation system is a car navigation (navigation) system.

In a car navigation system that has been put into practical use, a so-called autonomous navigation system that combines a GPS with a so-called autonomous navigation system in which the position of a vehicle is tracked by a traveling distance sensor or an angular acceleration sensor and the current position is calculated is calculated. The system is also widely used and is effective for more accurate position display.

By the way, from the viewpoint of proper operation, for example, delivery (delivery), taxi service, patrol service of a security company, and emergency service by an administrative organization, from the viewpoint of proper operation, for example, delivery is required. A base station installed in a center or police station, etc.
It is desirable to be able to grasp it arbitrarily.

Therefore, a vehicle serving as a mobile station is provided with position detecting means such as a car navigation system, and the current position of the vehicle is detected and reported to the base station successively, so that the base station knows the vehicle position and displays it on a map. Can be displayed above,
A so-called car locator system has been put to practical use and widely used.

FIG. 5 shows an example of a car locator system according to the prior art. The whole system is roughly divided into a base station B and a mobile station M, and a dedicated radio channel is provided between them. Data is to be transmitted. Then, first, the mobile station M is a vehicle equipped with a car navigation system, for example, an automobile, and although not shown in the figure, the number of the mobile stations M is not limited to one, but may be the number of automobiles requiring monitoring. Accordingly, the number of stations becomes two or more. Actually, there are many cases where a plurality of stations are provided.

Next, the base station B, for example,
It is installed at the center of the system, and includes a radio device 10, a communication control device 11, a console 12, and a display device 13 as shown in the figure. The wireless device 10 includes a transmitting device and a receiving device, communicates with the mobile station M under the control of the communication control device 11, and takes in the position information of the mobile station transmitted from the mobile station M. The operation of transmitting the position information by the mobile station M at this time is automatically and sequentially performed at a cycle of, for example, 200 mS or sequentially in response to a call from the base station B.

As described above, the communication control device 11 controls the wireless device 10 and causes the display device 13 to display a map of a predetermined range on the basis of display map information prepared in a predetermined memory in advance. Further, based on the acquired position information, the position of the mobile station is displayed on a map displayed on the display device 13 by, for example, an arrow or a figure representing a car. At this time, the monitor uses the console 12 as necessary to perform desired processing such as selection of a destination, communication with the selected mobile station, or change of the position display state. .

Next, the mobile station M comprises a radio device 20, a signal processing device 21, and a car navigation device 22.
The radio device 20 includes a transmitting device and a receiving device, and
And transmits position information and receives commands from the base station. The signal processing device 21 controls the radio device 20 and also controls the car navigation device 22, takes in positional information from the device, performs necessary processing, and supplies the processed information to the radio device 20.

The car navigation device 22 stores a GPS receiver 221, an angular acceleration sensor 222 for autonomous navigation, a vehicle speed sensor 223, and road position information, centering on a car navigation control device 220 that controls the entire operation. A memory card 224 and a GPS antenna 225 attached to the GPS receiver 221 are further provided.

First, the GPS receiver 221 receives data from at least three GPS satellites via the GPS antenna 225, calculates the position of its own mobile station, and supplies it to the car navigation controller 220 as GPS position information. Work. Angular acceleration sensor 222 and vehicle speed sensor 2
Reference numeral 23 serves to detect the angular acceleration appearing in the vehicle equipped with the mobile station and the running speed of the vehicle and to input them to the car navigation control device 220.

Therefore, this car navigation control device 220
Based on the angular acceleration and running speed input from these sensors, the running position of the vehicle is tracked starting from a predetermined position, and position information by autonomous navigation is calculated. Then, the information is corrected by mutual matching between the position information obtained by the autonomous navigation and the position information given from the GPS receiver 221.
The corrected position information is compared with the road position information read from the memory card 224, the position of the own mobile station is specified by map matching, the specified position information is input to the signal processing device 21, and the base station is The station B is caused to transmit.

As a result, on the map screen displayed on the display device 13 of the base station B, the position on the road of the mobile station M existing within the range of the map is, for example, an arrow or the like as described above. Will be represented by the shape of
According to this car locator system, the position of the vehicle in operation can be easily and accurately grasped while staying at the base station B, and it is possible to sufficiently carry out the necessary tasks accurately.

By the way, in the case of such a car locator system, a radio communication channel for data transmission between the mobile station and the base station is approved and constructed by a person who needs the car locator system and constructed. In this case, when the operation area required is wide, base stations are arranged at different positions and operated by a plurality of base stations.

Here, an example of a communication system permitted for a dedicated radio channel in such a system is as follows. Carrier frequency: 400MHz band Single frequency Communication method: One-way arbitrary call communication from mobile station to base station Data transmission speed: 8kbps Applications: Dedicated to car locator system

The above prior art does not take into account the fact that a large number of base stations are required to expand the operation area, and there is a problem in that the cost increases with the expansion of the operation area. Further, the above prior art does not consider that there is a limit to the number of mobile stations that can be supported by each base station, and has a problem that traffic is concentrated on a wireless communication channel.

That is, in the prior art, since the communication area for each base station is limited, an increase in the number of base stations is required to expand the operation area, so that a substantial increase in cost cannot be avoided. In addition, the restriction on the communication system imposes a restriction on the traffic volume that can be handled by each base station, so that the number of mobile stations accommodated per unit base station is limited.

An object of the present invention is to provide a wireless data transmission system which can easily cope with a wide operating area at low cost. It is another object of the present invention to provide a wireless data transmission system in which the number of mobile stations that can be handled by each base station can be further increased under a protocol for a communication system.

[0018]

SUMMARY OF THE INVENTION The object of the present invention is to provide a wireless data transmission system in which a mobile station transmits its location information to a base station via a wireless communication channel, and the base station displays the location of each mobile station. This is achieved by providing two wireless communication channels between each of the mobile stations and the base station, and transmitting the location information of the mobile stations by switching these two wireless communication channels. At this time, one of the two wireless communication channels may be a wireless communication channel dedicated to the system, and the other may be a public wireless communication channel.

At this time, the switching of the two wireless communication channels is performed when the mobile station moves from a communication area of one of the two wireless communication channels to a communication area of the other of the two wireless communication channels, and It may be executed when at least one of the states when the data processing amount by one of the wireless communication channels reaches a certain limit appears.

The above object is also achieved in a wireless data transmission system in which a mobile station transmits its own location information to a base station via a wireless communication channel, and the base station displays the location of each mobile station. And two radio communication channels are provided between the base station and the base station, and information for determining the timing of transmission of position information by each mobile station is transmitted from the base station to each mobile station by one of the two radio communication channels. Achieved as transmitted.

At this time, one of the two radio communication channels is a radio communication channel dedicated to the system, the other is a public radio communication channel, and the information for determining the transmission timing of the position information is the public radio communication channel. May be transmitted via the.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a wireless data transmission system according to the present invention will be described in detail with reference to the illustrated embodiments. FIG. 1 shows an embodiment of the present invention. In this embodiment, a base station B and a mobile station M are basically provided in the same manner as in the prior art described with reference to FIG. Then, first, the base station B has a dedicated receiver 1 and a switching control unit 2,
A telephone terminal 3, a communication control device 11, a console 12, and a display device 13 are provided.
Corresponds to the wireless device 10 in the prior art in FIG. 5, and the communication control device 11, the console 12, and the display device 13 are the same as those in the prior art in FIG.

Next, the mobile station M is provided with a dedicated transmitter 4 and a switching controller 5, a mobile phone terminal 6, a state setting device 7, a position detecting device 8, and a signal processing device 21. Here, the dedicated transmitter 4 corresponds to the wireless device 20 in the prior art of FIG. 5, the position detecting device 8 also corresponds to the car navigation device 22, and the signal processing device 21 is the same as the conventional technology. is there.

Therefore, also in the embodiment of FIG. 1, the switching control unit 2 of the base station B selects the receiver 1 and the mobile station M
When the switching control unit 5 selects the transmitter 4, it operates as the same car locator system as in the prior art in FIG. 5, and the position of the mobile station M is changed every moment as in the prior art in FIG. Is displayed on the display device 13.

Next, the switching control unit 2 of the base station B sets the data transmission path of the communication control device 11 to the receiver 1 and the telephone terminal 3.
The switching operation is controlled by the communication control device 11. The telephone terminal 3 is one of subscriber telephones in a public telephone facility, and is connected to a telephone station P in which a subscriber line of the public telephone facility is accommodated.

The public telephone facility is operated by a telephone company (telephone carrier) subscribed to the present system. In this public telephone facility, the telephone service includes a portable telephone channel. It also includes a call service.

Accordingly, the communication control device 11 is configured to be able to connect to the mobile phone channel which is also subscribed to by the present system through the subscriber's telephone terminal 3 by the operation of the switching control unit 2. Will be.

Next, the switching control section 5 of the mobile station M functions to arbitrarily switch the data transmission path of the communication control device 21 between the transmitter 4 and the portable telephone terminal 6, and the switching operation is performed by a signal processing device. 21.
The mobile telephone terminal 6 is one of the subscriber mobile telephones in the above-mentioned public telephone line network, and is assigned a specific call number under contract.

Therefore, through the portable telephone terminal 6, the communication control device 21 can communicate with the telephone terminal 3 of the base station B.
, A call connection can be arbitrarily made, and data can be mutually exchanged as necessary.

The state setting device 7 includes a manually operated switch and the like, and generates information indicating the state of the mobile station M.
The information representing the state of the mobile station M is input to the signal processing device 21. Here, for example, when the mobile station M is mounted on a police car, the mobile station M is in a normal round trip or an emergency trip. In this case, an output is generated in conjunction with the lighting operation of the emergency lamp.

For example, in the case of a taxi, the information indicates whether the vehicle is empty or actual. In this case, an output is generated in conjunction with the operation of the taxi meter. As a result, the signal processing device 21 can
Then, the state information given from the state setting unit 7 is added to the position information of the own vehicle detected by the above, and the position information is transmitted to the base station B by radio.

Then, the base station B displays the state of the mobile station transmitted based on the state information on a map together with its position. Here, in the case of a car locator system, this state information does not always need to be added, but in practice, it is often added for convenience. The display of the state information includes blinking and non-blinking of the image representing the position, a difference in displayed color, a difference in shape, and the like.
It is expressed in a form that can be easily recognized visually.

Next, the operation of the switching control unit 2 of the base station B and the switching control unit 5 of the mobile station M in the embodiment of FIG. 1 will be described. First, a data transmission path between the transmitter 4 of the mobile station M and the receiver 1 of the base station B, that is, a dedicated wireless channel is defined as a dedicated wireless communication network. A transmission path, that is, a transmission path of data provided via the mobile phone channel and the telephone station P, is defined as a public wireless communication network. here,
A communication network is a communication channel.

Here, the communication system of the mobile phone channel in the public wireless communication network is as follows, for example. Carrier frequency: 800 MHz band Multiple frequencies Communication method: Two-way dedicated communication between mobile station and base station Data transmission speed: 9.6 kbps Use: Public data communication (PC communication, etc.)

In this embodiment, it is enough to understand that a data transmission path can be formed between the telephone terminal 3 and the portable telephone terminal 6 anyway. Therefore, in FIG. Although shown as being composed solely of the telephone office P, this is for the sake of simplicity of description and notation, and it goes without saying that it actually consists of a much more complicated network.

One of the features of the present invention is that two radio communication channels are switched to obtain a function as a car locator system. It is also characterized in that the dedicated wireless communication network and the public wireless communication network are switched and used as the two wireless communication channels, and two modes are set for the switching. One.

Here, the first switching mode is a switching operation executed by the mobile station M taking the initiative when the mobile station M moves, and the second switching mode is received by the base station B. This switching operation is performed by the base station B taking the initiative in accordance with the amount of data (traffic). Therefore, first, regarding the first switching mode in this embodiment,
This will be described with reference to the flowchart of FIG.

Here, the signal processing device 21 of the mobile station M is provided with predetermined map information in advance in order to match the position of the own station detected by the position detecting device 8, but in this embodiment, Further, information on a dedicated wireless area BA by each base station B of the present system and a public wireless area PA by a public wireless communication network are also stored. At this time, the wireless area is an area where data can be transmitted to each base station B.

The signal processing device 21 is configured to execute the processing shown in FIG. 2 in addition to the processing necessary for the operation as the car locator system described above.
At this time, as an initial process when the operation of the mobile station M is started, the switching control unit 5 is set to select data transmission by the dedicated wireless communication network.

When the process of FIG. 2 starts, the signal processing device 2
1. First, in step S1, the position detection device 8 detects the current position of itself, and then in step S2,
It is checked whether the detected position of the own station is in the dedicated wireless area BA or the public wireless area PA.

Then, the determination result in step S2 is Y
(Affirmative), that is, when it is determined that the detected position of the own station is still within the wireless area BA of the dedicated wireless communication network, the process returns to step S1 and the position is detected again. wait. At this time, the switching control unit 5 has selected the data transmission by the dedicated wireless communication network by the initial processing. Therefore, when the processing is started for the first time, until the determination result in step S2 becomes N (negative). , Step S1
And the process of step S2 is repeated.

At this time, the base station B displays the position of the mobile station M based on the position information fetched via the dedicated wireless communication network as a result of the above-described initial processing. Is maintained while the determination result in step S2 is Y, that is, while the mobile station M is in the wireless area BA by the dedicated wireless communication network.

Thereafter, when the result of the determination in step S2 is N, that is, when it is determined that the position of the currently detected own station is not within the wireless area BA, the process proceeds to step S3, where the process proceeds to step S3. The switching control unit 5 switches to the public wireless communication network. When the result of the determination in step S2 is N for the first time, the process also proceeds to step S3. Therefore, in this case, the processes in steps S1 and S2 are performed only once.

Here, the processing in step S3 is as follows. That is, the signal processing device 21 first accesses the mobile phone terminal 6 via the switching control unit 5 and performs a call operation required for establishing a public wireless communication network, such as transmitting the number of the telephone terminal 3 of the base station B. Let it run. Then, after the formation of the communication path between the mobile telephone terminal 6 and the telephone terminal 3 is confirmed, the switching control unit 5 switches from the dedicated wireless communication network to the public wireless communication network.

After step S3, the process proceeds to step S4,
Here, the position detection processing is executed again, and then, step S5
And again checks whether the detected position is within the wireless area BA of the dedicated wireless communication network. Therefore, this time, while the determination result in step S5 is Y, that is, until the mobile station M returns to the wireless area BA by the dedicated wireless communication network, steps S4 and S5 are performed.
Will be repeated.

At this time, the base station B displays the position of the mobile station M based on the position information fetched via the public wireless communication network since the processing of step S3 is performed. This state is maintained until the determination result in step S5 becomes N.

If the result of the determination in step S5 is N, that is, if the mobile station M has returned to the wireless area BA of the dedicated wireless communication network, the process proceeds to step S6. A process of switching from the public wireless communication network to the dedicated wireless communication network is performed, and the process returns to step S1,
Thereafter, the same processing is repeated.

Therefore, according to the processing shown in FIG.
An operation in which the transmission path of the position information and the status information from the mobile station M to the base station B is switched between a dedicated wireless communication network using a dedicated wireless channel and a public wireless communication network using a mobile phone channel in accordance with the position of the mobile station M. It will be obtained automatically.

As a result, even when the position of the mobile station M deviates from the wireless area BA by the dedicated wireless communication network, the transmission of the position information and the state information from the mobile station M to the base station B is not interrupted. As long as the location is within the service area of the public wireless communication network, the function as a car locator system can be maintained.

Here, in recent years, the service area of a public wireless communication network such as a cellular phone has been remarkably expanded, and it is not an exaggeration to say that the service area is almost nationwide. There is no particular problem except that the public line requires transmission costs (is charged).

Therefore, according to the embodiment using the first switching mode, it is not necessary to increase the number of base stations installed in the system when expanding the operation area, so that it is possible to suppress an increase in cost and to operate at low cost. Area enlargement can be obtained.

Here, since the dedicated wireless communication network is constructed as equipment dedicated to this system, its service area is restricted depending on the permissible cost and installation location.
For example, when a dedicated wireless communication network is built in the same prefecture, if base stations are installed in municipalities in the prefecture, the wireless area that can be covered at this time is about 30% to 40% in area ratio and 80% in population ratio. % To about 85%.

On the other hand, in the case of a public wireless communication network, for example, a communication carrier such as a mobile phone company installs it for ordinary users.
A service area of 90% or more can be expected in proportion to the population. Therefore, according to the above-described embodiment, a considerably large service area can be easily expanded.

Further, in the embodiment using the first switching mode, the determination processing in steps S2 and S5 is as follows.
Since the process is to check whether the position of the mobile station M is in the service area provided by the dedicated wireless communication network, the service area provided by the dedicated wireless communication network and the service area provided by the public wireless communication network overlap (overlap). In such a case, the dedicated wireless communication network is preferentially used.

Therefore, according to this embodiment, the use frequency of the public wireless communication network, which is charged and requires direct cost for data transmission, can be kept low, and the operation cost can be increased little. is there.

Next, the second switching mode in this embodiment will be described. In the first switching mode described above, switching between the dedicated wireless communication network and the public wireless communication network is performed by the movement of the mobile station M, with the mobile station M taking the initiative. The second switching mode described below is a switching operation executed by the base station B taking the initiative in accordance with the amount of received data at the base station B, as described above.

The operation in the second switching mode will now be described with reference to the flowchart of FIG. First, the process at this time is executed by the switching control unit 2 being controlled by the communication control device 11 in the base station B in FIG. When the process of FIG. 3 starts, first, in step S10, the amount of data received by the base station B via the dedicated wireless communication network is acquired. The unit of the received data amount at this time is the number of mobile stations per minute (number of stations)
It is.

Next, in step S20, it is checked whether the received data amount is equal to or more than 20 units / minute. If the result is N, that is, if the received data amount is less than 20 units / minute, the process returns to step S10, and the result is Y. If so, the process proceeds to step S30. here,
In each base station B, a plurality of mobile stations M are scheduled to be present in the communication area, but at this time, the processing capacity of data in each base station B is limited.

More specifically, in such a system, as described above, the dedicated wireless communication network
An arbitrary calling method using a single frequency is used, and the data transmission rate at this time is 8 kbps. Therefore, the number of mobile stations M that can be operated by one base station B, that is, one base station The number of mobile stations M existing in the communication area B is theoretically limited to 30 to 40 stations per minute.

Therefore, in the case of FIG. 3, step S20
Then, it is determined whether the received data amount is equal to or more than 20 units / minute in view of a margin. If the received data amount exceeds this value, the process overflows. Therefore, the process proceeds to step S30.

As described above, since the unit of the received data amount is the number of mobile stations per minute, this changes only with the number of mobile stations M existing in the communication area of the base station B. Is changed, and therefore, when returning from step S20 to step S10,
The same processing is repeated until the number of mobile stations M existing in the communication area of the base station B changes.

Thereafter, as a result of data input from a certain mobile station M, the determination result in step S20 becomes Y,
When proceeding to step S30, the communication control device 11 controls the telephone terminal 3 via the switching control unit 2, and requires the mobile telephone terminal 6 of the mobile station M at this time to establish a public wireless communication network. Execute a calling operation.

Then, after establishing the public wireless communication network,
At this time, the mobile station M is instructed to use the public wireless communication network for the subsequent data transmission. Specifically, as shown in the figure, the base station B sends data for instructing communication switching, whereby the signal processing device 21 of the mobile station M controls the switching control unit 5 to set the data transmission path to a dedicated It switches from a wireless communication network to a public wireless communication network.

Then, thereafter, the process proceeds to step S40,
The amount of received data by the dedicated wireless communication network of the base station B is fetched again, and then, in step S50, the amount of received data that has just been fetched is checked. If the result is N, the process returns to step S40.

Therefore, after that, the processing of steps S40 and S50 is repeated until the result of the determination in step S50 is Y, that is, the amount of data received by the dedicated wireless communication network becomes 10 units / minute or less. As a result, of the mobile stations M transmitting data to the base station B,
Once the mobile station M has been switched to data transmission by the public wireless communication network, the state is maintained until the number of mobile stations M transmitting data by the dedicated wireless communication network falls below ten. Will be done.

Then, the determination result in the step S50 is Y
Is satisfied, that is, when it is determined that the number of mobile stations M transmitting data through the dedicated wireless communication network has become 10 or less, step S60 is executed, and here, data transmission by the public wireless communication network is performed. Mobile station M being switched
Is instructed to return to data transmission by the dedicated wireless communication network.

Therefore, according to the embodiment using the second switching mode, it is not necessary to consider the traffic volume at each base station B, and the number of mobile stations M located within the communication area of the same base station can be reduced. Even if the number increases, the function as a car locator system can always be reliably maintained, and a highly reliable system can be provided.

Here, as described above, the first switching mode shown in FIG. 2 is a switching operation executed by the mobile station M taking the initiative, while the second switching mode shown in FIG. Is a switching operation executed by the base station B taking the initiative, and these may be used in combination.

In this case, when expanding the operation area, it is not necessary to increase the number of base stations installed in the system, so that the increase in cost can be suppressed, the operation area can be expanded at low cost, and the same base station can be obtained. Even when the number of mobile stations M located in the communication area of the station increases, the function as a car locator system can always be reliably maintained, and a highly reliable system can be realized.

Next, another embodiment of the present invention will be described with reference to FIG. As is apparent from FIG. 4, also in this embodiment, most of the system configuration is the same as that of the embodiment of FIG. 1, and the difference is that the switching control unit 2 of the base station B in the system of FIG. , The switching control unit 5 of the mobile station M is omitted.

As a result, in the case of the embodiment shown in FIG. 4, first, on the base station B side, the receiver 1 and the telephone terminal 3 are directly connected to the communication control device 11, respectively.
On the mobile station M side, the transmitter 4 and the mobile phone terminal 6 are each directly connected to the signal processing device 21.

Next, the operation of the embodiment shown in FIG. 4 will be described. First, also in this embodiment, the position information and the state information of the own station are sequentially transmitted from the mobile station M to the base station P in the communication area where the own station is located, thereby operating as a car locator system. The points are the same as the embodiment of FIG.

Here, also in this embodiment, the base station B
The point that two data transmission paths of a dedicated radio communication network and a public radio communication network are provided between the mobile station M and the mobile station M is the same as the embodiment of FIG. In the case of, the transmission of the position information and the status information from the mobile station M uses only the dedicated wireless channel by the dedicated wireless communication network.

In the data transmission path of the public wireless communication network, predetermined data necessary for the mobile station M to determine the transmission timing of the position information and the status information is transmitted from the base station B to the mobile station M. Supposed to be used for. Here, in this embodiment, the transmission reference time data and the system accommodation mobile station number data are transmitted from the base station B to the mobile station M as the predetermined data.

As described above, in the case of the embodiment shown in FIG. 1, the arbitrary transmission method (pure ALOHA method) is adopted for the timing of transmitting the position information and the state information from the mobile station M. This is the same in the prior art described with reference to FIG.

In the case of this arbitrary calling method, the timing of transmitting the position information and the status information in each mobile station M is independent of the transmission timing of the other mobile stations M and is independent. Therefore, when the number of mobile stations located in the same communication area increases, the traffic volume at the base station B in the communication area exceeds the processing capacity.

That is, in the case of this arbitrary calling system, the maximum traffic amount (throughput) on the radio line is 17%.
From this point of view, the number of mobile stations that can be accommodated in one base station is calculated to be about 30 to 35, and if the number of mobile stations exceeds this, processing cannot be performed.

Here, in the case of the embodiment using the second switching mode described with reference to FIG. 3, when the traffic volume at the base station B increases, the transmission of the position information and the status information is switched to the public wireless communication network. In this embodiment, the increase in the traffic volume in the dedicated wireless communication network is suppressed. However, in the embodiment of FIG. Can be applied to suppress an increase in traffic volume in a dedicated wireless communication network.

For this reason, in the embodiment of FIG. 4, the communication control device 11 of the base station B, for example, when the operation of the system is started, or when the number of mobile stations M existing in the communication area of its own station is increased. At a predetermined point in time such as when an increase or decrease occurs, predetermined data necessary to determine the transmission timing of the position information and the state information in each mobile station M, that is, transmission reference time data and system-installed mobile station number data, The data is sequentially transmitted to each mobile station M via a public wireless communication network.

At this time, the procedure for establishing a data transmission path by the public wireless communication network from the base station B to each mobile station M is as follows.
As described in the processing of step S30 and step S60 in FIG. 3, the communication control device 11 accesses the telephone terminal 3 and executes a calling operation such as transmitting the mobile phone number of each mobile station M. Ensure that a telephone channel is established.

When the mobile phone channel is established in this way and the data transmission path by the public wireless communication network is established, the signal processing device 21 of each mobile station M takes in data from the mobile phone terminal 6. Perform necessary processing and transmit data. Thereafter, the communication control device 11 transmits the transmission reference time data and the data on the number of mobile stations accommodated in the system.

Therefore, the signal processing device 21 of each mobile station M
Based on the transmission reference time data and the system-accommodated mobile station number data transmitted from the base station, based on the current time data and the data indicating the rank of the own station set in advance,
The timing for transmitting the position information and the state information from the own station is calculated.

Thereafter, until new transmission reference time data and system accommodation mobile station number data are given,
At this time, the position information and the state information are transmitted according to the calculated timing.

The timing calculated at this time is the transmission cycle given by the transmission reference time data, the number of data per cycle given from the data on the number of mobile stations accommodated in the system, and the transmission given by the data representing the rank of the own station. This depends on the position of the transmission time slot of the own station within the period.

Therefore, the position information and the state information transmitted from each mobile station M at each timing are sequentially arranged at predetermined time positions at regular time intervals for each mobile station M on the dedicated radio communication network. In addition, it can appear in accordance with a so-called slotted ALOHA system.

Here, in the case of this slot arbitrary calling system, the maximum traffic amount (throughput) on the radio line
Is 34%, which is about twice that of the prior art. Therefore, according to this embodiment, the number of mobile stations M that can be accommodated per one base station B is also doubled from 60 in the prior art to 70, and as a result, even more mobile stations can be accommodated. It can be easily handled.

In this embodiment, the data transmitted by the public wireless communication network is limited to the data necessary for each mobile station M to determine the transmission timing of the position information and the status information. The transmission is performed only when the operation of the system is started or when the number of mobile stations M existing in the communication area of the own station increases or decreases, for example.

Therefore, according to this embodiment, the use of the public wireless communication network requiring transmission costs (charging) can be suppressed to a considerably short time, and as a result, the increase in operation costs can be sufficiently suppressed. Can be.

Although the above embodiment has been described with reference to a case where a mobile telephone line is used as a public wireless communication network,
The embodiment of the present invention is not limited to this.
HS (personal handy phone system) may be used.

[0090]

According to the present invention, since the service area can be expanded without increasing the number of base stations installed, a wireless data transmission system which can easily cope with a wide operating area at low cost is provided. Can be easily provided.

Further, according to the present invention, the arbitrary slot calling system can be applied, so that the number of mobile stations that can be handled by each base station can be further increased, and 60 to 70 mobile stations can be accommodated. A wireless data transmission system that can be easily provided.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment in which a wireless data transmission system according to the present invention is applied to a car locator system.

FIG. 2 is a flowchart when the embodiment of the present invention is operated in a first switching mode.

FIG. 3 is a flowchart when an embodiment of the present invention is operated in a second switching mode.

FIG. 4 is a block diagram showing another embodiment in which the wireless data transmission system according to the present invention is applied to a car locator system.

FIG. 5 is a block diagram showing an example of a car locator system according to the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Receiver (dedicated system) 2 Switching control part 3 Telephone terminal 4 Transmitter (dedicated system) 5 Switching control part 6 Mobile telephone terminal 7 State setting device 8 Position detecting device 11 Communication control device 12 Operator console 13 Display device 21 Signal processing Equipment B Base station M Mobile station P Telephone station

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04L 12/28 H04L 11/00 310B (72) Inventor Shuji Kitazawa 4-6 Kanda Surugadai, Chiyoda-ku, Tokyo Stock (72) Inventor Koji Shibahara 6-27-18 Minamioi, Shinagawa-ku, Tokyo Hitachi, Ltd.Hitachi Omori Second Annex Building (72) Inventor Yuichi Onuki Minamioiroku, Shinagawa-ku, Tokyo No. 27-18, F-term (reference) 2F029 AA02 AB07 AC02 AC06 AC08 AC09 AC13 5H180 AA12 AA14 AA15 BB05 BB15 CC12 FF05 FF10 FF22 FF24 FF32 5K033 AA09 CB01 DA01 A19A02K0 EE10 FF03 FF23 JJ12 JJ39 JJ52

Claims (5)

[Claims] 1. A wireless data transmission system in which position information of a mobile station is transmitted from a mobile station to a base station through a wireless communication channel, and the position of each mobile station is displayed at the base station. A wireless data transmission system, wherein two wireless communication channels are provided between stations, and the position information of the mobile station is transmitted by switching between these two wireless communication channels. 2. The wireless data transmission system according to claim 1, wherein one of the two wireless communication channels is a wireless communication channel dedicated to the system, and the other is a public wireless communication channel. . 3. The invention according to claim 1, wherein the switching of the two wireless communication channels is performed when the mobile station moves from a communication area of one of the two wireless communication channels to a communication area of the other of the two wireless communication channels. A wireless data transmission system configured to execute when at least one state appears when a data processing amount by one of the two wireless communication channels reaches a certain limit. 4. A wireless data transmission system in which a mobile station transmits its own location information to a base station via a wireless communication channel and displays the location of each mobile station at the base station. Two radio communication channels are provided between the stations, and the information that determines the transmission timing of the position information by each mobile station is provided by one of the two radio communication channels.
A wireless data transmission system configured to be transmitted from the base station to each of the mobile stations. 5. The invention according to claim 4, wherein one of the two wireless communication channels is a wireless communication channel dedicated to the system and the other is a public wireless communication channel, and the transmission timing of the position information is determined. A wireless data transmission system, wherein information is transmitted via the public wireless communication channel.