JPH11355300A - Radio communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily set radio slave stations even in the case of the occurrence of a section where propagation conditions are unfavorable and to always perform sure and efficient data communication regardless of the change in weather conditions or environment. SOLUTION: Each of radio slave stations 1A to 1J is provided with two data communication controllers 5A and 5B which can individually transmit a generated data signal at the time of the transmission mode and can receive individually transmitted data signals at the time of the reception mode, radio parts 6A and 6B, and a controller 4 which operates a communication data signal generation part 4a capable of generation of a data signal to be transmitted at the time of the transmission mode and operates a data signal selection part 4c capable of selecting the data signal of less error out of two received data signals at the time of the reception mode.

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 applied to, for example, a system in which the status of pumps installed in pipelines and equipment installed in an automation factory is reported to a central management office. The present invention relates to a wireless communication system that transmits various data signals by radio waves using a space as a transmission medium between at least one wireless slave station and one master station.

[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]

By the way, in radio communication using free space as a transmission medium, line noise increases due to electric field fluctuation due to the influence of the reflected wave of the ground or the radio duct, that is, fading, or instantaneous interruption occurs. Is easy to occur. Therefore, when deciding the line route and the setting position of the wireless slave station, it is preferable to avoid such a section where the propagation conditions are poor. Difficulty,
Considering many factors such as economy, it is inevitable that a section with poor propagation conditions will occur.

In such a section where the propagation conditions are not good,
Even a slight movement of the position corresponding to a half wavelength of the wireless slave station greatly changes the reception electric field strength (reception energy), and reduces the reception efficiency and quality of the data signal. Therefore, when setting the wireless slave station, it is necessary to search for an optimum position where the received electric field strength is large, and it takes a great deal of effort to set. In addition, the refractive index of the atmosphere, which is one of the factors that affect the received electric field strength, changes depending on weather conditions and is unstable over time, and the received electric field strength also fluctuates due to environmental changes around the circuit route. However, it is extremely difficult to always keep the wireless slave station at the optimal receiving electric field position, and there is a problem that communication reliability is lacking.

[0005] The present invention has been made in view of the above-mentioned circumstances, and even if a section having poor propagation conditions occurs, the setting of a wireless slave station is easy, and a reliable and efficient radio station is always provided regardless of weather conditions and environmental changes. It is an object of the present invention to provide a wireless communication system capable of performing good data communication.

[0006]

In order to achieve the above object, a radio communication system according to the present invention uses a radio wave having a space as a transmission medium between at least one radio slave station and a master station. In a wireless communication system for transmitting a data signal, a wireless slave station can transmit a created data signal simultaneously or with a predetermined time difference when in a transmission state, and simultaneously when a reception state is in a reception state. Or 2 capable of receiving a data signal transmitted at a predetermined time interval.
Two transmission / reception means, when in a transmission state, a data signal to be transmitted can be created, and when in a reception state,
Means for selecting an error-free data signal from the two received data signals.

According to the present invention, the transmitting / receiving means of the wireless slave station can transmit two data signals simultaneously or with a predetermined time difference, and receives two data signals and receives the two data signals. Since the data signal is duplicated so that an error-free data signal can be selected from the two data signals, not only the mechanical reliability can be improved, but also the position of the wireless slave station can be freely provided. However, it is possible to efficiently receive a data signal having no error due to the diversity effect. Therefore, when setting the wireless slave station, it is not necessary to search for the optimum position where the received electric field strength is large, and the setting becomes easy even in a section where the propagation condition is not good, and it is possible to respond to changes in weather conditions and environment, The reliability of the predetermined data communication can be improved.

[0008] In particular, in the wireless communication system having the above-described configuration, as described in claim 2, one of the two transmitting / receiving means is set to the transmitting state and the other is set to the receiving state. By adopting a configuration including means for enabling reception to operate in parallel, transmission and reception on different lines can be concurrently performed, and data communication can be speeded up.

Further, in the wireless communication system having the above configuration, a plurality of the wireless slave stations are scattered in a predetermined area, and a range in which a transmission radio wave reaches each of the plurality of wireless slave stations. By adopting a configuration including a means for transmitting and receiving data signals between a plurality of other wireless slave stations within the plurality of wireless slave stations, a plurality of wireless slave stations scattered in a certain area can serve as relay stations. As a result, it is possible to construct a transmission line that is networked over a relatively wide and long range, and is located at a position where a plurality of slave stations among the scattered slave stations cannot directly communicate with the master station due to transmission output. Even if it exists, it enables wireless communication from any slave station within a certain area to the master station without requiring the installation of a special relay station equipped with a relay transmission / reception device (repeater), and performs transmission. output It is possible to build a network of wireless communication regardless economically.

[0010]

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 includes a measuring unit 3 for measuring contact data and analog data, a controller 4, two data communication controllers 5A and 5B, a data signal To antennas 7A and 7B
And two data communication controllers 5A and 5B, two radio units 6A and 6B for transmitting and receiving
B and a mode selection unit 8 that can switch the operation mode of the two radio units 6A and 6B between a transmission mode and a reception mode.

When the controller 4 in the wireless slave stations 1A to 1J having the above configuration is in the transmission mode, the controller 4
Data generation unit 4a capable of creating a data signal for communication in a format according to the communication procedure based on measurement data obtained by
And a signal converter 4b capable of converting the communication data signal into a signal suitable for transmission by radio waves, and a data communication controller 5A, 5B received by the two wireless units 6A, 6B when in the reception mode. Input 2
A data signal selector 4c for selecting an error-free data signal among the three data signals, that is, selecting a correctly received data signal and outputting the selected data signal to a data output unit 9 such as a CRT or a printer. Also, when in the transmission mode, the two radio units 6A and 6B receive the same communication data signal output from the controller 4 via the two data communication controllers 5A and 5B, and receive one of the radio signals. After the transmission from the unit 6A is completed, the signal is transmitted from the other wireless unit 6B,
In addition, in the reception mode, the two communication data signals transmitted are received, and the received two communication data signals are transmitted to the two data communication controllers 5.
A and 5B are input to the data signal selection unit 4c of the controller 4.

The communication data generator 4a of the controller 4 assigns priorities to transmission destinations to two other slave stations within a receivable range when transmitting a communication data signal. 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 data 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 addition, when each of the slave stations 1A to 1J is the transmission source, the priority order of the two transmission destinations is higher in FIG.
Is lower.

Further, the two destination slave stations, for example, 1
In general, the priorities of A and 1C are set such that 1A having a smaller spatial distance has a higher priority.
For example, in the case where there is a shield having a large space propagation loss in the middle of the transmission line, the 1C side having a small space propagation loss has a higher priority on the 1C side having a small space propagation loss even if the space distance is long in consideration of the receiving sensitivity. May be set.

Next, a communication operation of a data signal by the wireless communication system having the above configuration will be described with reference to flowcharts of FIGS. FIG. 3 shows the wireless slave stations 1A to 1
J is an operation flow of a radio station on the reception mode side (destination) when one of the radio stations is in the transmission mode, and another radio station within a range capable of receiving transmission radio waves therefrom is in the reception mode. When a data signal is transmitted from the transmission mode side (transmission source) slave station, the two wireless units 6A and 6
After B receives the same data signal, it inputs the received data signal to the data signal selector 4c of the controller 4. The data signal selection section 4c selects the data signal having no error from the two received data signals and performs CR
The data is output to the data output unit 9 such as T or a printer (steps S11 to S14).

FIG. 4 shows an operation flow of the radio station on the transmission mode side, for example, when an abnormality occurs in the measurement data of the measuring unit 3 in the radio station 1I and a failure occurs in the contact point or the device to be measured. Alternatively, when there is a request for data transmission from the master station 2 to the slave station 1I, the communication data generation unit 4a of the controller 4 in the wireless slave station 1I converts the measurement data from the measurement unit 3 into communication data in a format according to the communication procedure. Create a signal. At this time, two destination slave stations (slave stations on the transmission mode side) within a range in which the transmission radio wave can be received,
For example, the priority of 1A and 1C is checked, and a communication data signal including the address of the higher-order destination slave station 1A is created.
b, the radio wave is transmitted from one wireless unit 6A via the data communication controller 5A,
Two destination slave stations 1A and 1C within the range of the radio wave
Is called (steps S21 to S24).

Each of the two destination slave stations 1A and 1C checks the address in the communication data signal, and the higher priority slave station 1A whose address matches the address of its own slave station is the source slave station. A response signal is returned to the station 1I, and a communication link between the two stations 1I and 1A is established by the communication link processing between the two stations.
A transmits a communication data signal to the destination slave station 1A (steps S25 to S27).

At this time, if the response signal does not return within a predetermined time from the higher-priority destination slave station 1A to the source slave station 1I, the source slave station 1I determines whether the communication data signal Destination slave station 1 with lower priority
After creating a communication data signal changed to the address of C and converting the signal, the radio wave is retransmitted from the radio unit 6A in the same manner as above, and the two destination slave stations receiving the retransmitted radio wave are transmitted. 1A and 1C, upon receiving a response signal returned from the lower-priority destination slave station 1C having the same address as the changed address and the own address, a communication link between the two stations is established, and the source slave station 1I From the wireless unit 6A to the destination slave station 1A
The communication data signal is transmitted to the
29, S23, S27).

As described above, when the transmission of the data signal from the radio unit 6A of the above-mentioned source slave station 1I to the destination slave station 1A or 1C is completed, the data communication controller 5A of the source slave station 1I transmits the data signal. The controller 4 having received the notification of the transmission end signal transmits the same communication data signal from the other wireless unit 6B to the destination slave station 1A or 1C via the other data communication controller 5B (steps S30 to S30). S32). At this time, the destination slave station 1A or 1C on the receiving side operates as shown in the flow of FIG. 3, selects an error-free data signal, and outputs it to the data output unit 9 such as a CRT or a printer.

It is to be noted that a certain wireless slave station is in a reception mode as shown in FIG. 3, and while the two wireless units 6A and 6B are both receiving data signals, a contact of the own station or a device to be measured may fail. Occurs, or when there is a request for data transmission from the master station 2, the communication data generation unit 4a of the controller 4 creates a communication data signal in a format in which the measurement data from the measurement unit 3 follows the communication procedure. Then, while one radio unit 6A is maintained in the reception mode, only the other radio unit 6B and the data communication controller 5B are switched to the transmission mode to start transmission of the communication data signal created. And reception can be performed simultaneously, and the speed of data communication can be increased.

Further, as in the above-described embodiment, the plurality of wireless slave stations 1A to 1J are scattered in a certain area, and each of the plurality of wireless slave stations 1A to 1J is located within a range where a transmission radio wave can reach. By adopting a configuration in which data signals can be transmitted and received between a plurality of other wireless slave stations, a plurality of wireless slave stations scattered within a certain area serve as relay stations, and are relatively large. It is possible to construct a transmission line networked over a long range, and in the case where a plurality of slave stations among the scattered slave stations are located at a position where direct communication with the master station is not possible due to transmission output. Even without the need for a relay station, wireless communication from any slave station within a certain area to the master station is possible, making it possible to economically construct a wireless communication network regardless of the transmission output. Kill. However, the present invention is not limited to such wireless communication networking, and is applicable to a wireless communication system including one wireless slave station and one master station.
Similar effects can be obtained.

[0022]

As described above, according to the present invention, not only can the mechanical reliability be improved by duplicating the transmission / reception means of the wireless slave station, but also error-free due to the diversity effect. Data signals can be received reliably and efficiently. Therefore, it is not necessary to search for the optimal position where the received electric field strength is large when setting the wireless slave station. Even in a section where the propagation conditions are not good, the setting of the wireless slave station becomes easy, and the change in weather conditions and environment changes. And the reliability of predetermined data communication can be improved.

In particular, according to the second aspect of the present invention, in addition to the above-mentioned effects, it is possible to speed up data communication by simultaneously performing transmission and reception on different lines. According to the third aspect of the present invention, even if a relay station that poses many problems such as a rise in establishment costs and difficulty in round-trip maintenance is not set up, a master station can be established from any slave station within a certain area. Wireless communication is possible, and networking of wireless communication can be economically established regardless of the transmission output.

[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 communication operation in a reception mode in a wireless communication operation of a data signal by the system.

FIG. 4 is a flowchart illustrating a communication operation in a transmission mode in a wireless communication operation of a data signal by the above system.

[Explanation of symbols]

 1A to 1J Wireless slave station 2 Master station 4 Controller 4a Communication data generation unit 4c Data signal selection unit 5A, 5B Data communication controller 6A, 6B Wireless unit 8 Mode selection 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 at least one wireless slave station and a master station, wherein the wireless slave station is in a transmission state. At this time, it is possible to transmit the created data signal at the same time or at a predetermined time difference, and, when in the receiving state, to transmit the data signal transmitted at the same time or at a predetermined time difference.
Receiving means, and means capable of creating a data signal to be transmitted when in the transmission state and selecting an error-free data signal among the two received data signals when in the reception state. A wireless communication system, comprising: 2. The wireless slave station further comprises means for setting one of the two transmission / reception means to a transmission state and the other to a reception state so that transmission and reception can be performed in parallel.
A wireless communication system according to claim 1. 3. A plurality of said wireless slave stations are scattered in a certain area, and each of said plurality of wireless slave stations transmits a data signal between other plurality of wireless slave stations within a range of transmission radio waves. 3. The wireless communication system according to claim 1, further comprising means for enabling transmission and reception.