JPH11225106A - Radio communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To execute radio communication from all the slave stations to a master station without installing a special repeater station by allowing the plural radio stations dotting within a fixed area to play the role of repeater stations so as to construct a transmitting line networked through a prescribed range. SOLUTION: When data communication is requested to a slave station 1I from the master station 2, the slave station 1I prepares a data signal for communication. At this time, a data signal including the address of a transmission destination slave station 1A of a higher priority order of two transmission destination slave stations 1A to 1C existing in a range capable of receiving a transmission radio wave is prepared. Then, after signal conversion, the two stations 1A and 1C are called. The two stations 1A and 1C respectively check an address in a transmission data signal and only the station 1A whose address is coincident with that of its own slave station and whose order is set to be high transmits a response signal to the station 1I. A communication link is established between both stations by this response.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio communication system which is used, for example, when the status of pumps installed at a plurality of pipelines and equipment installed at a plurality of automation factories is reported to a central management office. For communication systems, in detail, a plurality of radio slave stations are scattered in a small fixed area, and various radio waves are transmitted between the plurality of radio slave stations and one master station by using radio waves using a space as a transmission medium. The present invention relates to a wireless communication system adapted to transmit a data signal.

[0002]

2. Description of the Related Art A radio communication system of this type uses a free space as a transmission line, and does not require continuous wired facilities between transmission stations. Lines can be easily created even in large cities where installation of wired facilities is difficult due to the increase in underground facilities and traffic conditions, etc. It has the advantage that it can be restored quickly and that the cost of the entire line can be reduced compared to the wired method.

By the way, when introducing wireless communication using free space as a transmission medium, it is necessary to prevent mutual interference with radio communication radio waves used by many organizations such as electric power companies, electric railway companies, broadcasting companies and police. For this reason, the Radio Law restricts the use frequency band, the transmission output, the modulation method, and the like. Therefore, in order to obtain a wireless communication system over a wide range, it is necessary to increase the transmission output, but the transmission output cannot be freely selected,
This is a factor that limits the expansion of the transmission capacity and transmission range.

[0004] Under such circumstances, as a wireless communication system that secures a transmission line that is relatively wide and long, conventionally, relay stations have been installed at regular intervals determined by the transmission output, and the relay station has been installed. A relay-type wireless communication system has been proposed and put into practical use, in which a radio wave attenuated by transmission of a signal is amplified by a relay station and then transmitted to the next relay station.

[0005]

However, in the above-mentioned relay-type wireless communication system, not only a large installation cost is required for the equipment of the relay station such as a relay transmission / reception device (relay), but also the relay station has many relay stations. In such a case, it is often installed in a remote place on a mountain in order to increase the line-of-sight distance, so that there is a problem that it requires considerable labor and cost for patrol maintenance and the like. In particular, when wireless communication is networked within a certain area, the above-mentioned relay type has significant problems in terms of economy, maintenance, etc., and has a technical problem that it is not possible to sufficiently secure the advantage compared with the wired type. there were.

The present invention has been made in view of the above-mentioned circumstances, and it is not necessary to install a relay station regardless of the transmission output, and a transmission line networked in a relatively large and long area within a certain area is provided. It is an object of the present invention to provide a wireless communication system that can be constructed economically and that can constantly monitor each transmission line and prevent useless access to a line in which an abnormality has occurred.

[0007]

In order to achieve the above object, a wireless communication system according to the present invention includes a plurality of wireless slave stations scattered in a fixed area and one master station.
A wireless communication system for transmitting a data signal by radio waves using a space as a transmission medium, wherein each wireless slave station includes:
Means for transmitting a data signal and a test signal to a plurality of other slave stations within a range where transmission radio waves can reach, and a predetermined priority when a data signal transmitted from a specific slave station is received. Means for operating to establish a communication link between the own station and the source slave station on the basis of the above, and when the plurality of destination slave stations are all disconnected, the source slave station to the own slave station A means for attempting to transmit to another destination slave station when returning a non-connection signal and receiving the non-connection signal, and a test signal transmitted periodically or irregularly from a specific child station. Means for transmitting a reception response signal to the transmission source slave station while transmitting the identification number of the transmission destination slave station having no response signal to the own station to the master station via another transmission destination slave station. The master station has the identification number of the destination slave station that has no response signal. Upon reception, means for searching for a plurality of slave stations within the range of transmission radio waves from the slave station of the identification number, and transmitting the identification numbers of slave stations having no response signal to the searched slave station. Means.

In the present invention having the above-described configuration, a plurality of wireless slave stations scattered within a certain area serve as relay stations, and construct a transmission line networked over a relatively wide and long range. Therefore, even when a plurality of slave stations among the scattered slave stations are in a position where direct communication with the master station cannot be performed due to transmission output relation, a special transmission / reception device (repeater) including a relay transmission / reception device is provided. It is possible to establish a wireless communication network economically regardless of the transmission output by enabling wireless communication from any of the slave stations within the certain area to the master station without the need for a relay station. is there.

When a data signal is transmitted from a specific slave station, a plurality of destination slave stations establish a communication link between the own station and the source slave station based on a predetermined priority. Act to establish, and if multiple destination slave stations are still unreachable, return a disconnection signal to the source slave station and attempt to transmit to the other destination slave station, thereby reparenting the data signal. It is possible to reliably transmit data from a location that cannot be directly transmitted to the station to the master station via a plurality of networked transmission lines.

In addition, a plurality of destination slave stations periodically or irregularly transmit a test signal from each wireless station at a rate of, for example, once to several times a day, so that the radio waves reach the station. Determine the presence or absence of a response signal from the destination slave station within the range, and if the destination slave station has an error and no response signal, give the master station the identification number of the abnormal slave station without the response signal. By transmitting the fact and also transmitting the fact to a plurality of source slave stations having the abnormal slave station as a destination, it is possible to monitor whether all the wireless slave stations are normal or not on a network basis. Yes, it is possible to prevent useless access to the transmission line including the abnormal slave station in the communication of the data signal thereafter.

[0011] In the above-mentioned radio communication system, the configuration of the radio child station for transmitting the data signal and the test signal is as follows.
4. A configuration in which a plurality of slave stations within a range where transmission radio waves from the own station can reach are set as transmission destinations, and transmission priorities are assigned to the plurality of destination slave stations in advance. Alternatively, any of the above configurations may be adopted in which each of the above-mentioned wireless slave stations is given a transmission priority when another slave station within a range where the transmission radio wave can reach becomes a transmission source.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a conceptual diagram of a wireless communication system according to the present invention, in which 1A, 1B, 1
C,..., 1J are each a plurality of radio stations scattered in a fixed area, 2 is one master station, and each of the radio stations 1A to 1J transmits free space to the master station 2 as a transmission medium. The data signal is transmitted by a radio wave.

As shown in FIG. 2, each of the wireless slave stations 1A to 1J communicates with a measuring unit 3 which measures contact data, analog data, and the like in a format in accordance with a communication procedure of the data measured by the measuring unit 3. Communication data generating unit 4 for generating a data signal for use and a test signal
A signal conversion unit 5 for converting (modulating) the communication data signal and the test signal into a signal suitable for transmission by radio waves, and transmitting and receiving the converted data signal and test signal radio waves via the antenna 6 And a communication control unit 8 that controls operations of the signal conversion unit 5 and the wireless unit 7 to control transmission and reception.

When the communication data generation unit 4 creates the communication data signal and the test signal, the communication data generation unit 4 in each of the wireless slave stations 1A to 1J having the above configuration has a transmission radio wave within a receivable range. Destinations to certain two other slave stations are set and input with priorities in advance, and the addresses of the two destination slave stations are entered. For example, when the slave station 1I is the transmission source, the slave stations 1A and 1C are set as the transmission destinations, and the transmission destination slave station 1I transmits to the transmission destination slave station 1
The transmission to A is set to have priority, and a data signal and a test signal including the addresses of the slave stations 1A and 1C are created. When the slave station 1A is the transmission source, the destination slave stations are 1B and 1E, and the slave station 1B is set to have priority. In the case where each of the slave stations 1A to 1J is the transmission source, the priority order of the two transmission destinations is higher in FIG. 1 and lower in priority.

In addition, the above-mentioned two destination slave stations, for example, 1A
And 1C are generally set such that 1A having a smaller spatial distance has a higher priority, but for example, a shield having a large spatial propagation loss exists in the middle of a transmission line. In this case, in consideration of the receiving sensitivity, the priority may be set to be higher in the 1C side where the spatial propagation loss is smaller even if the spatial distance is longer.

Next, a communication operation of a data signal by the wireless communication system having the above configuration will be described with reference to a flowchart of FIG. For example, there is an abnormality in the data measured by the measuring unit 3 in the wireless slave station 1I, and a failure occurs in the contact point or the device to be measured, or data communication from the master station 2 to the slave station 1I via a public telephone line or the like. Is received, the communication data generation unit 4 of the slave station 1I creates a communication data signal in a format according to the communication procedure of the measurement data by the measurement unit 3. At this time, the priority of the two destination slave stations 1A and 1C in the range where the transmission radio wave can be received is checked, and a data signal including the address of the destination slave station 1A having the higher priority is created. After the signal conversion, a radio wave is transmitted from the communication unit 7,
Two destination slave stations 1A and 1C within the range of the radio wave
Is called (steps S11 to S14).

Each of the two destination slave stations 1A and 1C capable of receiving the transmission radio wave from the slave station 1I checks the address in the transmission data signal, and the address matches the address of its own slave station. Only the slave station 1A whose is set to the higher order responds to the sender slave station 1I (answer)
The source slave station 1I that has transmitted the signal and received the answer signal returns to the reception standby state (step S15).

At this time, if the answer signal does not return within a predetermined time from the higher-order destination slave station 1A, the self-address of the lower-order destination slave station 1C and the transmission data signal are returned. Since the address does not match the address in the data signal, the source slave station 1I replaces the address portion in the data signal with the destination slave station 1C having a lower priority.
After the data signal changed to the address is created and the signal is converted, the communication unit 7 retransmits the radio wave. Then, the two destination slave stations 1A, 1A,
Of the 1C, only the destination slave station 1C having a lower priority order and having its own address that matches the address after the change transmits an answer signal to the source slave station 1I (step S1).
6, S17, S13 to S15).

As described above, the two destination slave stations 1
If either A or 1C responds, the source slave station 1I
A communication link process is performed between the communication terminal and the destination slave station 1A or 1C to establish a communication link between the two stations. In this state, the data signal is transmitted from the source slave station 1I to the destination slave station 1A or 1C. Is transmitted (steps S18 to S20).

When the transmission of the data signal from the source slave station 1I to the destination slave station 1A or 1C is completed, the slave station 1A or 1C is set as the transmission source for 2 seconds.
Transmission to one of the destination slave stations 1B, 1E or 1E, 1A is performed (step S21), and further transmission from 1B or 1E to the master station 2 is performed, thereby causing a failure or a request for data communication. The data signal of the existing slave station 1I is transmitted to the master station 2 using a plurality of slave stations as relay stations.

Here, if neither of the two destination slave stations is disconnected and transmission is not possible, a "disabled" answer signal is returned to the source slave station to the own slave station, and the reply is made. The source slave station receiving the signal changes the address of the other destination slave station and attempts transmission to the other destination slave station. For example, if the transmission from the slave station 1B to the master station 2 is interrupted, the slave station 1B returns a "disconnected" answer signal to the slave station 1B, and receives the "disconnected" answer signal.
B attempts transmission to another slave station 1F.

Hereinafter, in the same manner, two
When transmission to one destination slave station cannot be performed, the data signal can be reliably transmitted to the master station 2 by returning to the slave station of the transmission source and switching to another transmission line.

In the wireless communication system having the above configuration, the test signals are transmitted periodically or irregularly at a rate of, for example, once to several times a day, so that the plurality of wireless slave stations 1A to 1J can transmit the test signals. The operation status can be monitored. Hereinafter, the monitoring operation by transmitting the test signal will be described with reference to the flowchart in FIG. In this monitoring operation, each of the wireless slave stations 1A to 1J respectively
As in the case of the above-described data signal communication operation, the two destination slave stations are set with priorities, so that the flow of the transmission radio wave is the same as the above-described data signal communication operation. The detailed description is omitted.

First, as shown in FIG. 4A, radio waves obtained by converting test signals are transmitted at arbitrary timings from the wireless slave stations 1A to 1J, and two transmission destinations within a range where the radio waves can reach. It is determined whether there is a reception response signal from the station (steps S31 and S32). If there is a response signal from both of the destination slave stations, it is determined that the destination slave station is in a normal operating condition. Here, if one of the destination slave stations has an abnormality and there is no response signal. In this case, the identification number ID of the abnormal slave station having no response signal is transmitted to the master station 2 (step S33).

On the other hand, as shown in FIG.
When an identification number ID of an abnormal destination slave station having no response signal is received from a wireless slave station to which a test signal has been transmitted, two transmission sources within a range where transmission radio waves from the slave station having the identification number ID reach. After searching for the slave stations from their identification number IDs, the identification numbers of the destination slave stations that did not have the response signal are transmitted to the two searched source slave stations to notify the abnormal situation ( Steps S34 to S36).

In the communication of data signals after a specific slave station is determined to be abnormal by the above monitoring operation, useless access to the transmission line including the abnormal slave station should be avoided. By doing so, it is possible to efficiently transmit the data signal to the master station 2, and it is possible to easily repair the slave station in which an abnormality has occurred while maintaining such a wireless communication operation.

In the above embodiment, two destinations are set for each of the source slave stations 1A to 1J. However, three or more destinations may be set.

In the above embodiment, each of the wireless slave stations 1
A description has been given of a configuration in which, when the own station is the transmission source, transmission priorities are assigned in advance to a plurality of (two) destination slave stations within the reach of the transmission radio wave to each of A to 1J. , For each of the wireless slave stations 1A to 1J,
A configuration may be adopted in which a transmission priority is given when the own station becomes a transmission destination whose transmission source is another slave station within a range of transmission radio waves.

[0029]

As described above, according to the present invention, a plurality of wireless slave stations scattered in a certain area are configured to play the role of a relay station. Wireless communication from any slave station within a certain area to the master station without the need for installing a special relay station equipped with Can be constructed very economically. Moreover, when transmitting a data signal from a specific slave station, a plurality of destination slave stations operate so as to establish a communication link between the own station and the source slave station based on a predetermined priority. However, even if a plurality of destination slave stations are still disconnected, transmission to another destination slave station is attempted, so that a plurality of transmission lines networked from places where data signals cannot be directly transmitted to the master station. , The data can be reliably transmitted to the master station.

In addition, by transmitting a test signal periodically or irregularly at a rate of once to several times a day, for example, the reception response signal from the destination slave station within the range of the radio wave can be transmitted. By confirming the presence / absence, it is possible to monitor whether all the wireless slave stations are normal or not on a network basis, thereby preventing unnecessary access to the transmission line including the abnormal slave station during normal data signal communication. This has the effect that the maintenance can be easily performed, such as repairing the wireless slave station in which the abnormality has occurred, and repairing.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of a wireless communication system according to the present invention.

FIG. 2 is a schematic configuration diagram of a wireless slave station in the same system.

FIG. 3 is a flowchart illustrating a wireless communication operation of a data signal by the system.

FIG. 4A is a flowchart illustrating an operation of the wireless slave station at the time of monitoring by transmitting a test signal in the above system. (B) is a flowchart for explaining the operation of the master station at the time of monitoring by transmitting a test signal in the above system.

[Explanation of symbols]

 1A to 1J Wireless slave station 2 Master station 4 Communication data generation unit 5 Signal conversion unit 7 Wireless unit 8 Communication control unit

 ──────────────────────────────────────────────────続 き Continued from the front page (72) Inventor Hiroyuki Kawakatsu 1-1-1 Nakamiya Oike, Hirakata City, Osaka Prefecture Inside Kubota Hirakata Factory Co., Ltd.

Claims (3)

[Claims] 1. A wireless communication system for transmitting a data signal by radio waves using a space as a transmission medium between a plurality of wireless slave stations scattered in a certain area and one master station, Each of the wireless slave stations transmits a data signal and a test signal to a plurality of other slave stations within a range where transmission radio waves can reach, and when receiving a data signal transmitted from a specific slave station, Means for operating such that a communication link is established between the own station and the source slave station based on the determined priority order; and When a non-communication signal is returned to the source sub-station and the non-reception signal is received, means for attempting transmission to another destination sub-station and a specific sub-station periodically or irregularly While receiving the test signal transmitted to the Means for transmitting a reception response signal to the station, and transmitting an identification number of a destination slave station having no response signal to the own station to the master station via another destination slave station. Means for searching for a plurality of slave stations within the range of transmission radio waves from the slave station having the identification number when receiving the identification number of the destination slave station having no identification number, and a response signal to the searched slave station. Means for transmitting an identification number of a slave station having no wireless station. 2. A plurality of slave stations within a transmission radio wave range from the own station are set as destinations in each of the wireless slave stations, and transmission priorities for the plurality of destination slave stations are set in advance. The wireless communication system according to claim 1, which is provided. 3. The wireless station according to claim 1, wherein each of the wireless slave stations is assigned a transmission priority in a case where another slave station within a range of the transmission radio wave of the own station becomes a transmission source. Communications system.