JPH11355296A - Radio communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inexpensively construct a network system of radio communication in a fixed area and to surely transmit a data signal to a master station without losing it even in the case that any slave station cannot communicate or has a communication abnormality. SOLUTION: When a transmission request occurs in one of plural radio slave stations 1A to 1J dotted in the fixed area, the data signal can be transmitted to a master station 2 through plural transmission lines made into a network with the other slave stations as repeating stations. In this radio communication system, the transmitted data signal is stored and held in the local station until the local station receives both a response signal returned to the local station from the transmission destination slave station, which receives the transmitted data signal from the local station, and a response signal returned to the local station from the next transmission destination slave station, which receives the data signal transmitted from the transmission source of the repeating slave station which received the data signal, through repeating slave stations.

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. Regarding communication systems, in detail, a plurality of wireless slave stations are scattered in a small fixed area, and a radio wave using a space as a transmission medium is provided between the plurality of wireless slave stations and one master station. A wireless communication system adapted to transmit various data signals.

[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.

[0003] When introducing wireless communication using free space as a transmission medium, in order 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. The transmission law and the modulation method are regulated by the Radio Law. 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, which limits transmission capacity and the expansion of the transmission range. ing.

[0004] Under such circumstances, as a wireless communication system for securing a relatively wide and long transmission line, relay stations are installed at regular intervals determined by the transmission output, and transmission from a slave station is performed. A relay-type wireless communication system is conceivable in which a radio wave attenuated by a signal is amplified by a relay station and then transmitted to the next relay station. In this relay-type wireless communication system, a relay station such as a relay transmitting / receiving device (repeater) is used. In addition to the large installation costs required for these facilities, relay stations are often installed in remote places on the hills, etc. in order to increase the line-of-sight distance, which requires considerable labor and cost for patrol maintenance and the like. It costs. In particular, when wireless communication is networked within a certain area, the relay type system has major problems in terms of economy, maintenance, etc., and there is a technical problem that it is not possible to sufficiently secure the advantage compared with the wired type. .

[0005] Therefore, the applicants of the present application have made it possible for each of a plurality of wireless slave stations scattered within a certain area to play the role of a relay station, so that a plurality of wireless slave stations and a master station are located between the wireless slave stations. A wireless communication system comprising a plurality of transmission lines capable of transmitting data signals via radio waves using space as a transmission medium has been proposed and a patent application has been filed. According to the wireless communication system proposed by the applicants of the present application, even from a slave station located at a position where direct communication with the master station cannot be performed, data signals can be transmitted to the master station by relaying other slave stations. This is advantageous in that a wireless communication network can be economically constructed as compared with the above-mentioned relay system.

In the wireless communication system proposed by the applicants of the present invention, a request for transmission of a data signal occurs to a specific wireless station, and when a data signal is transmitted in response to the request, a transmission radio wave arrives. A response signal indicating that another slave station within the range and serving as a relay station has received the data signal is returned to the sender slave station. The source slave station receiving this response signal ends the transmission operation at that time, and then the slave station that has received the data signal becomes the transmission source and relays the data signal to the next slave station. The station also employs a data signal transmission confirmation means that terminates the relay transmission operation when receiving a response signal returned from the next slave station.

[0007]

In a wireless communication system employing the above-described transmission confirmation means, for example, a slave station which has received a data signal transmitted from a wireless slave station which has requested transmission. Becomes the transmission source and relays the data signal to the next destination slave station, if all of the next destination slave stations are disconnected or exhibiting an abnormality, the transmission source slave station ( The relay station) must notify the transmission source slave station to the local station of the state of communication failure or communication abnormality. However, at this time, the source slave station has already completed the transmission operation, and may not be in a state where it can receive the status of communication failure or communication abnormality such as being used as a transmission line of another data signal. The data signal disappears, and there is a possibility that failure information or the like in the data signal cannot be transmitted to the master station, so that there is room for improvement in the reliability of the communication system.

The present invention has been made in view of the above circumstances, and not only can a transmission line networked within a fixed area over a relatively wide and long area be constructed economically, but also each radio station can be economically constructed. It is an object of the present invention to provide a communication system capable of significantly improving the reliability of the entire system by improving the performance of confirming the transmission of a data signal.

[0009]

In order to achieve the above object, a wireless communication system according to the present invention provides a plurality of wireless slave stations scattered within a certain area to each of which a request to transmit a data signal is issued to the own station. When it occurs, a means for transmitting a data signal to one of a plurality of slave stations within a range where transmission radio waves from the own station can reach, and a data signal transmitted from a slave station other than the own station are received. Means for relaying the received data signal to one of a plurality of slave stations within a range where transmission radio waves from the own station can reach, and providing a means for relaying between the plurality of wireless slave stations and the master station. In a wireless communication system in which a plurality of transmission lines for transmitting data signals via radio waves using a space as a transmission medium is provided between each wireless slave station, when a data signal is transmitted from the own station, Is the destination slave station that received the data signal And the response signal sent back to the local station,
When the destination slave station relays and transmits a received data signal as a transmission source, a response returned from the next destination slave station that has received the data signal to the own station via the source slave station. Means for storing a data signal until both of the signals are received, and, when both response signals are received, means for erasing the stored data signal and terminating the transmission operation of the own station. Things.

According to the present invention having the above-described structure, a plurality of wireless slave stations scattered in a certain area serve as relay stations to construct a transmission line networked over a relatively wide and long range. Therefore, even if a plurality of slave stations among the scattered slave stations are located at a position where direct communication with the master station cannot be performed due to the relationship of transmission output, a relay transmission / reception device (repeater) is provided. It is possible to establish a wireless communication network economically regardless of the transmission output by enabling wireless communication from any slave station in the above-mentioned fixed area to the master station without requiring a special relay station. It is possible.

In addition, a failure or the like occurs in a specific wireless slave station, a data signal transmission request is generated, and one of a plurality of slave stations within a range where a transmission radio wave from the own station reaches in response to the request. When a data signal is transmitted to the local station, the data signal received from the destination station is returned to the local station. And a response signal returned when the destination slave station serving as a relay station transmits a data signal to the next slave station as a normal reception of the data signal by the slave station. The signal is stored as it is, and transmission confirmation means is provided to delete the data signal and end the transmission operation of the own station only after receiving both response signals, so that communication with one of the slave stations as the relay station is impossible. Or communication error Even if there is a situation, the situation is notified to the slave station one stage prior to the source slave station of the own station to prevent the data signal from disappearing, and the transmission request is sent using another transmission line. It is possible to reliably transmit the data signal to the master station.

In particular, in the case where a response signal is not returned from the destination slave station even after a certain period of time has elapsed from the time when a data signal was transmitted from the own station to the wireless slave station as described in claim 2, By providing a means for retransmitting the data signal to another one of the plurality of slave stations within a range where the transmission radio wave from the own station can reach, the slave station that has not returned the response signal is regarded as abnormal, The data signal can be transmitted to the master station as soon as possible using another transmission line, and the reliability of the entire system can be further improved.

In the above wireless communication system,
As a configuration of a wireless slave station that transmits a data signal, as described in claim 3, a configuration in which transmission priorities are assigned in advance to a plurality of slave stations within a range where transmission radio waves from the own station reach, or As described in claim 4, any of the configurations in which the reception priority is given when another slave station within the range where the transmission radio wave from the own station can reach becomes the transmission source may be adopted.

[0014]

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 that measures contact data, analog data, and the like in a format according to a communication procedure based on data measured by the measuring unit 3. Signal generator 4 for generating a data signal for use, a signal converter 5 for converting (modulating) the data signal into a signal suitable for transmission by radio waves, and an antenna 6 for converting the radio waves of the converted data signal.
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.

On the other hand, as shown in FIG. 3, the master station 2 extends between a radio unit 10 for transmitting and receiving radio waves via an antenna 9 and the master station 2 among the above-mentioned radio slave stations 1A to 1J. A signal converter 11 that converts (demodulates) data signals transmitted from the slave stations 1B, 1E, and 1F within a range in which radio waves can be transmitted and received to original measurement data and outputs the data to a data output unit 12.
And a communication control unit 13 that controls operations of the radio unit 10 and the signal conversion unit 11 to control transmission and reception.

The communication control unit 8 in each of the wireless slave stations 1A to 1J includes a response signal returned from a destination slave station that has received a data signal transmitted from the own station, and a destination slave station that has received the data signal. The data signal is stored and held until both the response signal returned from the next destination slave station that receives the data signal relay-transmitted as the transmission source via the above-mentioned source slave station (relay station) is received, Further, a memory capable of erasing a data signal stored when both response signals are received is provided. Further, when creating a data signal, if there are two other slave stations within a range where a transmission radio wave from the own station can reach, the data signal creation unit 4 determines in advance the transmission destinations to the two slave stations. A priority is set and input, and the addresses of the two destination slave stations are entered. For example, when the slave station 1I is set as the transmission source, the slave stations 1A and 1C are set as the destinations, and the transmission from the source slave station 1I to the destination slave station 1A is set so as to be prioritized. A signal including the addresses of the slave stations 1A and 1C is 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 the slave stations 1A to 1J are the transmission sources, the priority order of the two transmission destinations is higher in FIG. 1 and lower in FIG.

Note that the above 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 signal communication operation of the wireless communication system having the above configuration will be described with reference to a flowchart of FIG. For example, when there is an abnormality in the measurement data in the measuring unit 3 in the wireless slave station 1I, a failure occurs in the contact point or the device to be measured, or a request for data transmission from the master station 2 to the slave station 1I is made. The communication data creation unit 4 in the wireless slave station 1I creates a communication data signal in a format in which the measurement data from the measurement unit 3 follows the communication procedure. At this time, the priority of the two slave stations 1A and 1C within the range where the transmission radio wave from the own station 1I reaches is checked, and the communication data signal including the address of the higher-order destination slave station 1A is checked. And the signal conversion unit 4
After that, the data signal is stored in the memory, and a radio wave is transmitted from the wireless unit 6 to call the higher-priority destination slave station 1A (steps S11 to S11).
S15).

The called destination slave station 1A checks the address in the data signal, and returns a response signal to the source slave station 1I when the address matches the address of its own slave station. The communication link between the two stations 1I and 1A establishes a communication link between the two stations, and the wireless unit 6 of the source slave station 1I transmits the higher priority destination slave station 1A.
Are transmitted (steps S16 to S1).
9).

At this time, if no response signal is returned from the higher-priority destination slave station 1A,
At the source slave station 1I, a data signal in which the address portion in the data signal is rewritten to the address of the destination slave station 1C having a lower priority is created, and after signal conversion, radio waves are re-transmitted from the radio unit 6. The destination slave station 1C, which is transmitted and has a lower priority, is called, and the called destination slave station 1C returns a response signal to the source slave station 1I to send a response signal to both the slave stations 1I, 1C.
A communication link between the two stations is established by the communication link processing between the stations 1C, and a data signal is transmitted from the source slave station 1I to the destination slave station 1C having a lower priority (step S2).
0, S21, S13 to S19).

On the other hand, the two slave stations 1A and 1C within the range where the transmission radio wave from the destination sub station 1I can reach check the reception radio wave because there is no transmission request to the own sub station, and check the received data. Whether the signal is addressed to the local station,
Or, it is determined whether it is addressed to another slave station, and if it is addressed to another slave station, it waits for the next transmission, and if it is a data signal addressed to its own slave station, it is transmitted as described above. A response signal is returned to the requesting transmission source slave station 1I, and a data signal from the transmission source slave station 1I is received with the establishment of a communication link between both stations (steps S22 to S25).

Next, the destination slave station 1A or 1C that has received the data signal transmits the two slave stations 1B, 1E or 1C within the range where the transmission radio wave from the own station becomes a transmission source. The received data signal is relayed to 1E and 1A through substantially the same procedure as in steps S14 to S19 described above. In step 13, only the address portion in the data signal is rewritten.

As described above, in the transmission operation of the data signal from the transmission source slave station 1I to the transmission destination slave station 1A or 1C, the transmission request is returned from the transmission destination slave station 1A or 1C to the transmission source slave station 1I. Response signal and the destination slave station 1
A or 1C as a transmission source and its destination child stations 1B and 1E
Alternatively, at the time of the relay transmission operation of the received data signal to 1E, 1A, the destination slave station 1B, 1E or 1E, 1A returns to the source slave station 1A or 1C, and further, the slave station 1
It is checked whether or not both of the response signals returned from A or 1C to the transmission source slave station 1I that has requested transmission are received. When both response signals are received, the data signal stored in the memory is checked. Erase (reset) and send to slave station 1
The transmission operation of I ends (steps S26 and S27).

In step S26, if the reception of both response signals is not confirmed within a predetermined time t from the start of transmission of the data signal from the transmission source slave station 1I, the slave station is The destination slave station of the data signal from 1A or 1C is forcibly switched and the received data signal is retransmitted (step S28).

In the above embodiment, two transmission destinations are set for each transmission source slave station. However, three or more transmission destinations may be set.

In the above embodiment, each of the wireless slave stations 1
A to 1J has been described in which, when the own station becomes a transmission source, a transmission priority order is assigned in advance to a plurality of destination slave stations within the range of the transmission radio wave. Each of the slave stations 1A to 1I may be given a reception priority in a case where the slave station becomes a transmission destination whose transmission source is another slave station within a range of transmission radio waves.

[0028]

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.

In addition, when a failure occurs in a specific wireless slave station and a data signal transmission request is generated, only the response signal from the destination slave station that has received the data signal transmitted from the own station is used. Instead of terminating the transmission operation of the station and deleting the data signal, the response signal returned from the slave station when the destination slave station serving as the relay station transmits a data signal to the next slave station is transmitted to the own station. By performing a transmission confirmation function such as erasing the data signal and ending the transmission operation of the own station only after receiving, even if any of the slave stations serving as relay stations have a communication failure or communication abnormal situation,
The data signal can be prevented from disappearing, and the data signal requested to be transmitted can be reliably transmitted to the master station using another transmission line. Therefore, there is an effect that the reliability of the entire wireless communication system can be significantly improved.

In particular, according to the second aspect of the present invention, it is possible to transmit a data signal to a master station as soon as possible by using another transmission line by regarding a slave station that has not returned a response signal as an abnormality. Overall reliability can be further improved.

[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 schematic configuration diagram of a master station according to the same system.

FIG. 4 is a flowchart illustrating a wireless communication operation in the above system.

[Explanation of symbols]

 1A to 1J Wireless slave station 2 Master station 4 Communication data signal creation 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 (4)

[Claims] When a request for transmitting a data signal is issued to a plurality of wireless slave stations scattered within a certain area, each of the plurality of slave stations within a range where transmission radio waves from the own station reach. Means for transmitting a data signal to one of them, and when receiving a data signal transmitted from a slave station other than the own station,
Means for relay-transmitting the received data signal to one of a plurality of slave stations within a range where transmission radio waves from the own station can reach, between the plurality of wireless slave stations and the master station. In a wireless communication system in which a plurality of transmission lines for transmitting data signals through radio waves using a space as a transmission medium are provided, each wireless slave station transmits a data signal when a data signal is transmitted from its own station. A response signal returned from the destination slave station that has received the signal to the own station, and the next destination that received the data signal when the destination slave station relayed and transmitted the received data signal. The data signal is stored until both the response signal returned from the slave station to the own station via the transmitting slave station is received, and when both response signals are received, the stored data signal is deleted. To end the transmission operation of your station. A wireless communication system, comprising: 2. The wireless slave station receives a transmission radio wave from its own station if a response signal is not returned from a destination slave station even after a lapse of a predetermined time from when a data signal is transmitted from its own station. The wireless communication system according to claim 1, further comprising means for retransmitting the data signal to another one of the plurality of slave stations within the range. 3. The wireless communication system according to claim 1, wherein each of the wireless slave stations is given in advance a transmission priority order for a plurality of slave stations within a range where transmission radio waves from the own station can reach. . 4. A wireless communication system according to claim 1, wherein each of the wireless slave stations is assigned a receiving priority in a case where another slave station within a range in which a transmission radio wave from the own station can reach becomes a transmission source. A wireless communication system according to claim 1.