JPH06315183A - Radio data communication system - Google Patents

Abstract

PURPOSE:To provide a radio data communication system enabling the data communication from an arbitrary point of a prescribed communication area in an area where an existing radio data communication system can not be used. CONSTITUTION:A data communication terminal (PC) 5 is the terminal of a personal computer, etc., performing the data communication with a slave station 3 via a control station 4 and a repeating station 2. The control station 4 performs the communication control of a radio data communication system 1. The repeating station 2 performs data transmission and reception with the slave station 3, using each specified small power radio. Each repeating station 2 covers a prescribed range (communication zone) and performs data transmission and reception with the slave station 3 within this range. Further, by the aggregation of the communication zones of the repeating station 2, the whole of the range (communication area) shown by a rectangle in a Fig. is converted, and the data communication of both the slave station 3 at an arbitrary point of this range and a data communication terminal 5 is enabled. The slave station 3 performs the data communication with the data communication terminal 5 at an arbitrary point, using specified small power radio while moving within this communication area.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wireless data communication system in which a predetermined range is covered by communication areas of a plurality of relay stations and data communication is performed from an arbitrary place in the range.

[0002]

2. Description of the Related Art A service for performing wireless data communication in a predetermined area, such as a teleterminal system, is currently in operation mainly in Tokyo. Further, there is currently used an apparatus for performing data communication between personal computers used in the office or between a personal computer and a printer by using a specific low power radio, for example.

[0003]

There is a demand to perform data communication in a predetermined range, for example, an arbitrary point in a fixed range such as an amusement park, and to know the position of a cleaning vehicle or the like that moves within the range. In order to meet this requirement, it is possible to use the above-mentioned teleterm system.

Here, the above-mentioned teleterm system is currently located in the service area of National Route 16 mainly in Tokyo, and data communication is possible from any point in the service area. However, the service of this teleterm system is available only within the above range, and there is a problem that it cannot be used in other areas.

In order to meet the above demand, it is possible to use the data communication by the specific low power radio as described above. However, when data communication is performed using a specific low power radio, the transmission power is legally limited to 10 mW or less, so that the communicable range is extremely limited. Therefore, there is a problem that it cannot be used for data communication from an arbitrary point within a fairly wide range such as an amusement park.

The present invention has been made in view of the above-mentioned problems of the prior art, and in particular, in an area where an existing wireless data communication system such as a teleterminal system cannot be used, an arbitrary point within a range having a considerable area. It is an object of the present invention to provide a wireless data communication system that enables data communication from a device.

[0007]

In order to achieve the above object, a wireless data communication system of the present invention has a control device, a plurality of relay stations, and at least one slave station. A system for sequentially performing data communication with respect to a plurality of areas by time division wireless communication in a predetermined range constituted by a set of respective wireless communication ranges, wherein the control device is connected to each relay station via a wired line. The control signal transmission timing to the slave station is specified to cause the control signal to be transmitted to the slave station, and the relay station sequentially transmits the control signal to the slave station via the wireless line in accordance with the timing. , The slave station changes the delay time from receiving the control signal to returning a response based on the electric field strength of the control signal, and sends the control signal having the strongest electric field strength within the delay time. Serial returns a response control signal to select a relay station, characterized by connecting a communication line with the control station via the relay station.

Further, the slave station further has position measuring means for measuring its own position by using a radio signal from an artificial satellite, and the position measuring means is used when transmitting / receiving data to / from the control device. The position information indicating its own position measured by is transmitted to the control device.

Further, the control station further has a position management means, and the position management means sends the slave station that has transmitted the slave station response signal and the slave station response control signal of the slave station to the control station. The position of each of the slave stations is identified by associating with the relay station transmitted to.

[0010]

A plurality of relay stations that use a specific low power radio are installed in a predetermined range, and the predetermined range is covered as a whole system by a set of ranges (communication zones) in which each relay station communicates. It enables communication from any point within the range to at least one of these relay stations with a slave station moving within this range.

When the control station which controls the call of the relay station moves within the predetermined range and calls the slave station which communicates with the control station, the control signal of the slave station is transmitted to each relay station. Specify the sending timing and call the slave unit,
The collision of control signals from each relay station is prevented.

Further, by preventing the collision of the control signals from the relay stations as described above, it is possible to establish communication between a plurality of slave stations and the control station with one frequency. Further, by including the identification information of the relay station in the control signal sent by the relay station, based on the electric field strength of the control signal of each relay station received by the slave station, by selecting the relay station and returning the response signal,
A slave station that can communicate with multiple relay stations, for example, first sent a control signal, but avoids communication with a relay station whose electric field strength is weak due to being distant, etc., and always maintains communication quality above a certain level. .

[0013]

Embodiments of the wireless data communication system of the present invention will be described below. In the wireless data communication system 1, a relay station 2 that performs data communication by specific low power wireless is installed in a predetermined range, and a range in which each relay station 2 communicates (communication zone)
Is a communication system that covers a predetermined range such as an amusement park as a whole system and enables data communication between the slave station 3 and the data communication terminal 5 from an arbitrary point within this range. The relay station 2 and the slave station 3
Since there are a plurality of in the wireless data communication system 1, when it is necessary to distinguish them individually, they are distinguished by adding an alphabetic character to the code.

FIG. 1 is a diagram showing the configuration of a wireless data communication system 1 of the present invention. FIG. 2 is a diagram showing a communication zone formed by the relay stations 2a to 2l. In FIG. 1, a data communication terminal (PC) 5 is a terminal such as a personal computer that performs data communication with the slave station 3 via the control station 4 and the relay station 2 by using communication software, for example.

The control station 4 controls the communication of the wireless data communication system 1. Each of the relay stations 2a to 2l transmits / receives data to / from the slave station 3 using a specific low power radio. Each of the relay stations 2a to 2l covers a predetermined range (communication zone) as indicated by a circle in the drawing and transmits / receives data to / from the slave station 3 within this range, as shown in FIG. 2, for example.

Further, the entire communication range of the rectangle shown in the figure is covered by the set of communication zones of the relay stations 2a to 2l, and the slave station 3 and the data communication terminal located at any point in this range. 5 data communication is possible.
For example, in a place where there are relatively few obstacles, the antennas 24 of the relay stations 2a to 2l are placed at a height of 5 m above the ground and the slave stations 3a to 3l.
When the antenna 36 of j has a ground clearance of 2 m, the radius of each communication zone is about 300 m.

By arranging the communication zones formed by each of the twelve relay stations 2a to 2l with no gap and minimizing overlap, 1260 m (the vertical length of the rectangle in the figure) × 1590 m (in the figure) It is possible to cover a relatively wide range of the lateral length of the rectangle. By increasing or decreasing the number of relay stations 2 and installing the relay stations 2 so as to eliminate the dead range due to obstacles when performing communication in the communication area, communication of any size under any conditions Areas can be formed.

The slave stations 3a to 3j use a specific low power radio and are provided, for example, in a cleaning car or the like when the communication area of the wireless data communication system 1 is an amusement park, and while moving in this communication area, Data communication with the data communication terminal 5 is performed at an arbitrary point. In the wireless data communication system 1, the relay station 2 is connected to the control station 4 in a star shape. However, depending on the application, the relay station 2 may be formed into a bus type connection by multiplexing the lines of the plurality of relay stations 2. Alternatively, a mixture of these may be used.

Hereinafter, the slave station 3, the relay station 2, and the control station 4
The configuration of will be described. FIG. 3 is a diagram showing a configuration of the slave station 3. In FIG. 3, a position measuring device (GPS) 31 is generally a GPS (Global Positioning).
It is a device called “System” that measures the latitude and longitude of the position of the slave station 3 with an error of about several tens of meters by using radio waves from an artificial satellite received via the antenna 36. The CPU 32 includes, for example, a one-chip microprocessor and its peripheral circuits, and controls the entire slave station 3 and communication control between the relay station 2 and the slave station 3.

The transceiver (TRX) 33 is, for example, 400
It is a transceiver for specified low power wireless communication for MHz band,
Data transmission / reception between the relay station 2 and the slave station 3 is performed using radio waves in this frequency band. The antenna 37 is the transmitter / receiver 33.
Is the antenna of.

The terminal interface (I / F) 34 is
For example, an interface circuit for RS232C,
The CPU 32 and the data terminal 25 are interfaced.
The data terminal 25 is, for example, a personal computer, and performs data communication with the data terminal 25 via the control station 4 and the relay station 2 by communication software.

FIG. 4 is a diagram showing the configuration of the relay station 2.
In FIG. 4, the transceiver 21 is, for example, a transceiver for specific low power wireless communication for the 400 MHz band, and uses the same frequency as the transceiver 33 to transmit and receive data between the relay station 2 and the slave station 3. To do. The antenna 24 is the antenna of the transceiver 21.

Here, the data transmission rate between the transceiver 21 and the transceiver 33 is either 2400 pbs or 4800 pbs, and is either fixedly set at the start of system operation of the wireless data communication system 1. Alternatively, either one may be adaptively selectable depending on the state of data communication. That is, if the communication state between the transceiver 21 and the transceiver 33 is bad and a data error is likely to occur, the communication is performed at 2400 bps, and if the communication state is good, the communication may be performed at 4800 bps. Good. Also, other data rates, for example 1200 bp
Data may be transmitted / received by s or the like.

The CPU 22 comprises, for example, a one-chip microprocessor and its peripheral circuits, and controls communication between the slave station 3 and the relay station 2 and between the relay station 2 and the control station 4. The modem (MODEM) 23 modulates the data input from the CPU 22, converts the data into a signal that can be transmitted on a wired line, and sends the signal to the control station 4, and also a signal sent from the control station 4 via the wired line. Demodulate data from the CP
Input to U22.

FIG. 5 is a diagram showing the configuration of the control station 4.
In FIG. 5, the modems 41a to 41l are respectively shown in FIG.
Are provided corresponding to the relay stations 2a to 2l, and modulate the data input through the modem interface 42 into signals that can be sent out on the wired line.
The signal is demodulated from the signal transmitted from the relay station 2 via the wired line and input to the CPU 43.

Modem interface (MODEM I
/ F) 42 interfaces the CPU 43 with the modems 41a to 41l. The CPU 43 is composed of, for example, a general-purpose microprocessor, a ROM, a RAM, and its peripheral circuits, and controls communication between the data communication terminal 5 and the relay station 2 and the control station 4 as a whole. The terminal interface 44 is, for example, an interface circuit for RS232C, and includes the CPU 43 and the data communication terminal 5
Interface. The respective parts shown in the above-mentioned drawings are connected as shown in the drawings.

The operation of the wireless data communication system 1 will be described below with reference to FIG. FIG. 6 is a diagram showing a signal sequence among the slave station 3a, the relay stations 2a, 2b, 2e, the control station 4, and the data communication terminal 5 in the wireless data communication system 1. Here, as an example, a case will be described in which the slave station 3a is located as shown in FIG. 2 and can receive signals from any of the relay stations 2a, 2b, and 2e.

When performing data communication with the slave station 3a,
First, the data communication terminal 5 designates the slave station 3a and makes a call to the control station 4. Here, a unique identification code is set to each of the slave stations 3a to 3j, and the data communication terminal 5 notifies the control station 4 of the identification code 3a of the slave station 3a when making a call.

At this point in time, the control station 4 does not know the position of the slave station 3a. Therefore, the control station 4 receiving the call signal from the data communication terminal 5 sequentially calls all the slave stations 3a to 3l. Send a control signal. The call signal includes a control type code indicating the call of the slave station 3, an identification code 3a of the slave station 3a,
And for each of the relay stations 2a to 2l, the slave station 3a
Specifies the delay time for sending the control signal to.

After receiving the call signal, each of the relay stations 2a to 2l receives the signal of the frequency for immediate communication based on the control type signal and the identification code of the slave station 3 and does not interfere with other communication. Make a carrier sense to make sure. By setting the carrier sense time to a different value in each relay station 2, it is possible to prevent the collision of the control signals that occurs when a plurality of relay stations 2 send signals at the same time.

The relay stations 2a to 2l receiving the call control signal
Respectively sends control signals to the slave stations 3a sequentially according to the delay time. Here, this control signal is a control type code indicating the calling of the slave station 3 and an identification code 3 of the slave station 3a.
a, and the identification codes 2a to 2l of each relay station 2 are included.

Of the control signals from each relay station 2, the slave station 3a
The control signals from the relay stations 2a, 2b, 2e are received by the relay station. Here, the solid line indicates that only the control signal from the relay station 2a exceeds the predetermined electric field strength in the slave station 3a.
The dotted line indicates that the control signals from the other relay stations 2b and 2e did not exceed the predetermined electric field strength.

The slave station 3a identifies the control type of each control signal and the identification code of the slave station, and the identification code is the identification code 3
If it is a, the response process is started. However, child station 3a
Does not return a response to the relay station 2 until a predetermined response delay time has elapsed since the control signal was first received. The response delay time is set to be longer than the time required for all the relay stations 2 in the wireless data communication system 1 to complete the transmission of the control signal.

Next, the slave station 3a returns a response control signal to the relay station 2a whose electric field strength of the control signal exceeds a predetermined value. Here, the response control signal includes a control type code indicating the response control signal, an identification code 2a indicating the relay station 2a, and an identification code 3a for the slave station 3a.

For example, when the control signals from the plurality of relay stations 2 exceed the predetermined electric field strength, the response control signal is returned to the relay station 2 which sent the earliest control signal.

This response control signal is transmitted to the relay stations 2a, 2b, 2
It is received by any of e. However, as indicated by the dotted line in the figure, in the relay stations 2b and 2e, since the identification code 2a of the relay station 2a included in the response control signal does not match the identification code of its own, the subsequent processing is performed. Instead, it stays in the initial state. As shown by the solid line in the figure,
Only the relay station 2a matches the identification code of the relay station 2 in the response control signal with its own identification code, and therefore performs the subsequent processing based on this response control signal.

Upon receiving the data from the slave station 3a, the relay station 2a returns a data signal including a part of the response control signal to the control station 4. This data signal includes the control type code of the response control signal. In the wireless data communication system 1, when a plurality of data communication terminals 5 are prepared and data communication with a plurality of slave stations 3 is performed simultaneously, it is necessary to include the identification code of the slave station 3 in this response control signal. Also,
The identification code of the relay station 2 is not necessary because it can identify the received relay station 2 by associating it with the modem interface 42 that received the data signal, but may be included in the data signal as necessary.

The control station 4 receiving this data signal sends data to the data communication terminal 5. The contents of the data transmitted and received by this data communication include various information between the data communication terminal 5 and the data terminal 25, as well as the position information of the slave station 3a from the position measuring device 31.

The control of the data communication here is performed by the data communication terminal 5 and the data terminal 25, for example, BSC.
It is performed by the software that controls the protocol.

The position information of the slave station 3a measured by the position measuring device 31 and received by the data communication terminal 5 by the above data communication is stored in the data communication terminal 5. The position information of the slave station 3a is obtained by the data communication terminal 5 from the slave station 3a.
Updated every time you receive location information from. In addition, child station 3
Since position information can be obtained for b to 3l similarly to the slave station 3a, this position information is displayed on, for example, a CRT display connected to the data communication terminal 5. The user of the wireless data communication system 1 can obtain the position information by operating the data communication terminal 5 to call each of the slave stations 3, and grasp the position of the cleaning vehicle loaded with the slave stations 3. can do.

In the embodiment described above, each signal between the control station 4, the relay station 2 and the slave station 3 is added with a control type code indicating the control of that signal.
For example, when the wireless data communication system 1 is to perform data communication by simple control and always performs only the sequence shown in FIG. 6, this control type code is not always necessary.

Further, in the above embodiment, the relay station 2
Although the operation has been described with respect to the communication in which the a, 2b, and 2e and the slave station 3a are related, each unit of the wireless data communication system 1 performs the same processing in the communication in which the other relay station 2 and the slave station 3 are related. Also, the call from the slave station 3 side to the control station 4 is
This can be realized by performing a process that is almost the reverse of the control sequence shown in FIG.

Further, when the slave station 3 determines the relay station 2 which returns the response control signal, in the above embodiment, the relay station 2 having the predetermined electric field strength as the control signal is selected.
This selection method is not limited to the one described here, and for example, all the electric field strengths of the control signals received from each relay station 2 before the response delay time are stored, and the relay station 2 having the strongest electric field strength among them is stored. May be configured to be selected.

Further, the response delay time of the slave station 3 may be variable based on the electric field strength of the control signal received first.
That is, when the received control signal is strong, the slave station 3 determines that it is very close to the relay station 2 that has sent the control signal, shortens the response delay time thereafter, and the received control signal is very weak. In this case, the response delay time may not be shortened.

Further, the delay time for transmitting the control signal designated to each relay station 2 may be variable for each relay station 2. Further, when the control station 4 includes the data communication terminal 5, the signal sequence between the control station 4 and the data communication terminal 5 is unnecessary.

In the wireless data communication system 1 of the present invention, a plurality of relay stations using, for example, a specific low power radio are provided, and a predetermined communication area is covered by a set of communication zones of the relay stations. It is possible to configure a wireless data communication system capable of flexibly responding to the presence or absence of obstacles on radio wave propagation.

Further, by performing the processing as shown in the above signal sequence, it is possible to eliminate the collision of signals such as control signals in the data communication between the plurality of slave stations 3 and the relay station 2, and to perform the same processing. It is possible to handle a large number of slave stations 3 on the frequency. The wireless data communication system of the present invention can have various configurations other than the above-mentioned embodiments, for example, as shown as a modified example.

[0048]

As described above, according to the wireless data communication system of the present invention, it is possible to perform data communication from an arbitrary point in a predetermined communication area, and wireless data conforming to the conditions peculiar to the communication area. A communication system can be provided.
In addition, despite the fact that many relay stations and slave stations perform wireless data transmission and reception using the same frequency, the problem of communication failure due to control signal collision does not occur. Further, even in an area where the existing wireless data communication system cannot be used, it is possible to configure a wireless data communication system capable of performing data communication at an arbitrary point within a predetermined range.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a wireless data communication system of the present invention.

FIG. 2 is a diagram showing a communication zone formed by a relay station.

FIG. 3 is a diagram showing a configuration of a slave station.

FIG. 4 is a diagram showing a configuration of a relay station.

FIG. 5 is a diagram showing a configuration of a control station.

FIG. 6 is a diagram showing a signal sequence among a slave station, a relay station, a control station, and a data communication terminal in the wireless data communication system of the present invention.

[Explanation of symbols]

 1 ... Wireless data communication system 2 ... Relay station 21 ... Transceiver 22 ... CPU 23 ... Modem 24 ... Antenna 3 ... Slave station 31 ... Position measuring device 32 ... ..CPU 33 ... Transceiver 34 ... Terminal interface 35 ... Data terminal 36, 37 ... Antenna 4 ... Control station 41 ... Modem 42 ... Modem interface 43 ... CPU 44 ... Terminal interface 5 ... Data communication terminal

Claims (3)

[Claims] 1. A time-division wireless communication having a control device, a plurality of relay stations, and at least one slave station, and within a predetermined range constituted by a set of respective wireless communication ranges of the relay stations. A system for sequentially performing data communication with respect to a plurality of areas by means of the control device, in which response timing to the slave station is specified by designating timing of signal transmission to the slave station to each relay station via a wired line. Signal is transmitted, the relay station sequentially transmits a control signal to the slave station via the wireless line in accordance with the timing, and the slave station receives the control signal based on the electric field strength of the control signal. Change the delay time from returning the response to the response, select the relay station that has sent out the control signal with the strongest electric field strength within this delay time, return the response, and return the response via the relay station. Communication line with Wireless data communication system, characterized in that the connection. 2. The slave station further has a position measuring means for measuring its own position by using a radio signal from an artificial satellite, and the position measuring means is used when transmitting / receiving data to / from the control device. The wireless data communication system according to claim 1, wherein the wireless communication system transmits position information indicating the position of the self measured by the control device to the control device. 3. The control station further comprises position management means, the position management means reading the slave station which has transmitted the slave station response control signal and the slave station response control signal of the slave station. 3. The position of each of the slave stations is identified by associating it with a relay station that has transmitted data to a control station.
The wireless data communication system according to.