JP2010154179A - Wireless communication device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve the wireless communication device which can provide more significant power saving effect than before. <P>SOLUTION: The wireless communication device includes a wireless communication means having a function of measuring the RSSI value and the noise level during wireless communication, and switches the sleep mode in which the function of the wireless communication means is stopped at least partially and the active mode in which wireless communication is performed by operating the wireless communication means. The device further includes an operation control unit which performs wireless communication with a lower transmission power by controlling the wireless communication means when both the S/N ratio calculated from the RSSI value and the noise level and the RSSI value are larger than a prestored S/N ratio and a prestored threshold of RSSI value. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a wireless communication apparatus capable of reducing power consumption by stopping some functions during a period in which wireless communication is not performed, and in particular, relates to suppression of power consumption during transmission. .

  2. Description of the Related Art Conventionally, a wireless communication device that performs wireless communication operates with a minimum amount of power by stopping some functions of the wireless communication unit during a period in which wireless communication is not performed (hereinafter referred to as a sleep period) (sleep state). As a result, power saving is achieved by reducing power consumption during sleep and ensuring sleep time.

  As a prior art document related to such a wireless communication apparatus, there is the following Patent Document 1.

JP 2007-104174 A

  FIG. 4 is a configuration diagram illustrating a configuration example of a conventional wireless communication apparatus, and FIG. 5 is an explanatory diagram of transmission power in a sleep mode and an active mode of the conventional wireless communication apparatus.

  In FIG. 4, although not particularly illustrated, the wireless communication device 1 is connected to field devices and control devices such as sensors and actuators installed in a plant control system, for example, and is obtained from each field device. A description will be given assuming that various data is converted into data for wireless communication and transmitted / received via a wireless line.

  The wireless communication device 1 is mainly connected to a communication unit 11 that performs data communication by being connected to a sensor such as a flow meter or an actuator constituting a feedback control loop (not shown) and the like, and controls each function of the wireless communication device 1 to perform wireless communication. , And a part of the function of the wireless communication unit 14 is stopped during the sleep period to operate with the minimum necessary power, an application for performing wireless communication and a destination address of another wireless communication device For example, a wireless communication means 14 such as a wireless LSI for performing wireless communication with other wireless communication devices, a wireless antenna 15 for wireless transmission and reception, and the like.

  The wireless communication device 1 operates in two modes, a sleep mode and an active mode. The sleep mode is a state in which the function of the wireless communication unit 14 is disabled, and the function of the wireless communication unit 14 is enabled in the active mode. It is in a state. The arithmetic control unit 12 switches between the sleep mode and the active mode by controlling the validity / invalidity of the communication function of the wireless communication means 14.

  The communication unit 11, the storage unit 13, and the wireless communication unit 14 are each connected to the calculation control unit 12, and the wireless antenna 15 is connected to the wireless communication unit 14.

  In such a configuration, in the conventional wireless communication apparatus 1, when control data / measurement data is received from the field device via the communication means 11, the arithmetic control unit 12 converts these data into data for wireless communication, The wireless communication means 14 and the wireless antenna 15 are controlled to a destination (other wireless communication apparatus) described in the received data or a destination (other wireless communication apparatus) stored in the storage means 13 via a wireless line. To send. In other words, when receiving data from the field device, the arithmetic control unit 12 enables the communication function of the wireless communication means 14 and operates in the active mode.

  On the other hand, the arithmetic control unit 12 of the wireless communication device 1 controls the wireless communication means 14 and the wireless antenna 15 when data transmission via the wireless line (hereinafter referred to as wireless communication) is completed, and partially or partially performs the wireless communication function. Sleeping is performed by disabling all of them and / or by stopping some functions (for example, a calculation function, a timer function, etc.) of the calculation control unit 12.

  That is, when the data transfer via the wireless line of the data received from the field device is completed, the arithmetic control unit 12 disables the communication function such as the wireless communication unit 14 and operates in the sleep mode. For this reason, the conventional wireless communication apparatus uses only a minimum amount of power in the sleep mode, so that power consumption can be reduced as shown in FIG.

  Note that when the arithmetic control unit 12 of the wireless communication device 1 receives data from the field device via the communication unit 11 while operating in the sleep mode, the arithmetic control unit 12 resumes each function stopped in the sleep mode and operates in the active mode. .

  As described above, the conventional wireless communication device operates with the minimum necessary power by securing a sleep time during which a part of the functions of the wireless communication unit is stopped during a period in which wireless communication is not performed. Thus, it is possible to save power by reducing power consumption.

  However, in the conventional wireless communication apparatus, since the power consumption is the largest in the transmission / reception process performed during the operation in the active mode, the period of operation in the active mode becomes longer as the duty of the wireless communication becomes higher. There was a problem that the effect became poor.

  In addition, in the conventional wireless communication device, even when the communication distance between the wireless communication devices is short, wireless data is transmitted and received using a certain amount of power. Therefore, communication using more transmission power than necessary is performed. There is a problem that it may become a waste of electric power.

  The present invention solves the above-described problems, and an object of the present invention is to realize a wireless communication device capable of providing a power saving effect greater than that of the conventional one.

In order to achieve such a problem, the invention according to claim 1 of the present invention is:
A wireless communication unit having a function of measuring an RSSI value and a noise level at the time of wireless communication, and a sleep mode in which at least a part of the function of the wireless communication unit is stopped and active to execute the wireless communication by operating the wireless communication unit A wireless communication device for switching modes, wherein the S / N ratio calculated from the RSSI value and the noise level and the RSSI value are both larger than the S / N ratio and RSSI value threshold stored in advance. In this case, the wireless communication apparatus includes an arithmetic control unit that controls the wireless communication means to perform wireless communication with a smaller transmission power.

The invention according to claim 2 is the wireless communication apparatus according to claim 1, wherein the arithmetic control unit is
Communication quality calculating means for calculating an S / N ratio based on the RSSI value and the noise level;
A transmission output table in which a transmission power value necessary for data transmission to another wireless communication device via a wireless line is stored corresponding to the identification information of the wireless communication device;
Storage means for storing the transmission output table, the RSSI value and a threshold of the S / N ratio;
When both the RSSI value and the S / N ratio are larger than the respective threshold values, transmission output table management means for changing the transmission power value of the transmission output table to a smaller value;
Transmission output control means for controlling the wireless communication means and transmitting data to a transmission destination wireless communication apparatus at a power corresponding to a transmission power value corresponding to the wireless communication apparatus in the transmission output table. And

The invention according to claim 3 is the wireless communication apparatus according to claim 1 or 2, wherein the wireless communication means is
While receiving data from another wireless communication device via a wireless line, the RSSI value and noise level at the time of the wireless communication are measured, and communication quality data including these RSSI value and noise level is the transmission source of the data It transmits to a radio | wireless communication apparatus, It is characterized by the above-mentioned.

The invention according to claim 4 is the wireless communication apparatus according to any one of claims 1 to 3,
The communication quality calculating means includes
An S / N ratio is calculated based on communication quality data received from the other wireless communication device.

The invention according to claim 5 is the wireless communication apparatus according to any one of claims 1 to 4,
A communication means for transmitting / receiving data to / from a field device via a wired line;
And wireless communication means for transmitting and receiving data received from a field device via the communication means via a wireless line.

  The wireless communication device according to the present invention measures the communication quality related to wireless communication between other wireless communication devices, and when the communication quality exceeds both the threshold of RSSI and S / N ratio stored in advance. In addition, by transmitting with lower power at the time of transmission output, it is possible to provide a greater power saving effect than before without causing packet loss.

  FIG. 1 is a block diagram showing a configuration example of a wireless communication apparatus according to the present invention. The same reference numerals are given to the same parts as those in FIG.

  The difference between FIG. 1 and FIG. 4 is that, in FIG. 1, the storage means 13 stores a transmission output table 13A for storing transmission power values necessary for data transmission to a plurality of adjacent wireless communication devices. The point that the wireless communication means 14 measures the received signal strength (hereinafter referred to as RSSI (Receive Signal Strength Indication)) and the noise level related to wireless communication with other wireless communication devices, and the arithmetic control unit 12 sets the transmission output table 13A. A transmission output control means 12A for transmitting wireless data at each transmission power value; a communication quality calculation means 12B for calculating an S / N ratio (Signal to Noise ratio) based on the RSSI / noise level measured by the wireless communication means 14; And a transmission output table management means 12C for changing the transmission power value of the transmission output table 13A based on the calculated RSSI and S / N ratio. .

  Although not particularly shown in FIG. 1, the wireless communication device 1 is, for example, a plant control system in industrial automation, a water purification plant control system in factory automation, a building air conditioning / lighting system, FFHSE (Foundation Fieldbus High Speed Ethernet). (Registered trademark)) and connected to field devices and control devices such as sensors and actuators installed in the field. Control data and measurement data obtained from each field device are used for wireless communication. In the following description, it is assumed that the data is converted into data and transmitted / received via a wireless line.

  The wireless communication device 1 mainly includes a communication unit 11, an arithmetic control unit 12, a storage unit 13, a wireless communication unit 14 such as a wireless LSI for performing wireless communication with other wireless communication devices, and a wireless antenna for wireless transmission and reception. 15 or the like.

  The communication unit 11 is connected to the arithmetic control unit 12 and is connected to a sensor such as a flow meter or an actuator constituting a feedback control loop (not shown) or the like to perform data communication.

  The storage unit 13 includes a ROM, a RAM, an HDD, and the like, and is connected to the arithmetic control unit 12 to transmit data to an application for performing wireless communication, a destination address of another wireless communication device, and a plurality of adjacent wireless communication devices. The transmission output table 13A for storing the transmission power value necessary for this, and the RSSI threshold value and the S / N ratio threshold value used for the management of the transmission output table 13A are stored.

  The transmission output table 13A of the storage means 13 is necessary for transmitting the identification information, name or destination address of one or a plurality of wireless communication devices (for example, adjacent wireless communication devices) and data to these wireless communication devices. The transmission power value is stored in correspondence with the identification information, name or destination address of the wireless communication device.

  The RSSI threshold and the S / N ratio threshold stored in the storage means 13 cause packet loss extracted based on data obtained by measuring the communication quality of wireless communication with a predetermined transmission power under various environments in advance. No RSSI value and S / N ratio may be stored as threshold information.

  The wireless communication unit 14 has a function of measuring RSSI and noise level related to wireless communication with other wireless communication devices.

  The arithmetic control unit 12 is a CPU (Central Processing Unit) or the like, controls each function of the wireless communication device 1 to execute wireless communication, and stops some functions of the wireless communication unit 14 during the sleep period. The transmission power of the transmission output table 13A is set to a transmission power value that can reach the transmission destination without causing packet loss according to the communication quality every time data is transmitted. Update.

  In addition, the arithmetic control unit 12 transmits communication quality (RSSI / noise) related to wireless communication between the transmission output control means 12A for transmitting wireless data at each transmission power value in the transmission output table 13A and another adjacent wireless communication device. Communication quality calculation means 12B for calculating (level / S / N ratio), and the communication quality of the wireless communication is determined based on the RSSI and S / N ratio calculated by the communication quality calculation means 12B. Transmission output table management means 12C for updating / changing / adding the transmission power value of the output table 13A is provided.

  The arithmetic control unit 12 of the wireless communication device 1 controls the wireless communication unit 14 to operate in two modes, a sleep mode and an active mode. The sleep mode is a state in which the function of the wireless communication unit 14 is disabled, and the active mode is a state in which the function of the wireless communication unit 14 is enabled. The arithmetic control unit 12 switches between the sleep mode and the active mode by controlling the validity / invalidity of the communication function of the wireless communication means 14.

  FIG. 2 is an explanatory diagram of the operation of the wireless communication apparatus according to the present invention during wireless communication, in which the steps of the operation process are described. In FIG. 2, wireless communication by the wireless communication device 1 and the other wireless communication device 2 will be described. The wireless communication device 2 has the same configuration as the wireless communication device 1 of FIG.

  In step SP101, although not shown, when control data / measurement data is received from the field device via the communication unit 11, the transmission output control unit 12A of the arithmetic control unit 12 of the wireless communication apparatus 1 is described in the received data. Based on the destination (wireless communication apparatus 2) or the destination (wireless communication apparatus 2) stored in the storage means 13, the wireless communication means 14 is controlled and the transmission destination (wireless communication apparatus) is stored in the transmission output table 13A of the storage means 13. 2) Reading / extracting the transmission power value stored corresponding to the wireless communication device information (device name, destination address, identification information, etc.) and outputting a data signal including this transmission power value to the wireless communication means 14 ( Transmission).

  In step SP102, the wireless communication unit 14 controls the antenna 15 to use the power (corresponding to the transmission power value extracted from the transmission output table 13A) and the destination (wireless communication device 2) or storage unit described in the received data. The data is transmitted to the destination (wireless communication apparatus 2) stored in 13 via the wireless line.

  At this time, although not particularly shown, when control data / measurement data is received from the field device via the communication means 11, the arithmetic control unit 12 may convert these data into data for wireless communication.

  Further, the transmission output control means 12A of the wireless communication apparatus 1 can be set to an arbitrary transmission power value (for example, wireless communication means) when the transmission power value corresponding to the transmission destination wireless communication device is not stored in the transmission output table 13A. 14 (maximum value of transmission power that can be set in step 14)).

  That is, when the arithmetic control unit 12 receives data from the field device, the wireless communication device 1 enables the communication function of the wireless communication unit 14 as in steps SP101 to SP102 and operates in an active mode in which data transmission / reception is performed by wireless communication. become.

  In step SP103, the wireless communication unit of the wireless communication device 2 measures communication quality such as RSSI and noise level based on a received signal including data received from the wireless communication device 1 via a wireless line. Note that this operation is performed when the wireless communication apparatus 1 is also on the data receiving side.

  Here, any measurement method may be used as long as the noise level by the wireless communication means 14 can be measured. Specifically, the wireless communication means of the wireless communication device 2 performs measurement using the Energy Detect function when the wireless communication between the wireless communication devices 1 and 2 is wireless communication using IEEE802.15.4. If the wireless communication between the wireless communication devices 1 and 2 is wireless communication using IEEE802.11, the signal-to-noise radio estimation included in the PLCP SYNC field may be used.

  In step SP104, the wireless communication means of the wireless communication device 2 transmits the communication quality data including the RSSI and noise level in the wireless communication from the wireless communication device 1 to the wireless communication device 2 measured in step SP103 to the wireless communication device 1 as a wireless link. To send through. Note that this operation is performed when the wireless communication apparatus 1 is also on the data receiving side.

  In step SP105, when the communication quality calculation unit 12B of the arithmetic control unit 12 of the wireless communication device 1 acquires the RSSI and noise level data from the wireless communication device 2 via the wireless communication unit 11, the communication quality calculation unit 12B obtains the RSSI and noise level from the RSSI and noise level. The S / N ratio is calculated.

Specifically, the communication quality calculation unit 12B calculates the S / N ratio based on the following equation (1).
S / N ratio [dB] = (RSSI [dBm]-noise level [dBm]) (1)

  In step SP106, the transmission output table management means 12C of the arithmetic control unit 12 of the wireless communication apparatus 1 determines the communication quality in the wireless communication with the wireless communication apparatuses 1 and 2 and updates the transmission output value if necessary. Then, the RSSI and S / N ratio threshold values stored in the storage means 13 are acquired and compared with the RSSI and S / N ratio values calculated in step SP105.

  In step SP107, the transmission output table management unit 12C of the wireless communication apparatus 1 stores the RSSI and the S / N ratio value calculated in step SP105 when both are determined to be larger than the threshold values of the storage unit 13. The transmission power value corresponding to the destination wireless communication device stored in the transmission output table 13A of the means 13 is changed to a smaller and appropriate (minimum) transmission power value, and the process returns to step SP101.

  For example, the transmission output table management unit 12C may select an appropriate transmission power value list (transmission obtained by calculating or experimenting in advance) according to the RSSI value and the S / N ratio value stored in advance in the storage unit 13. The transmission power value corresponding to the RSSI value and the S / N ratio value obtained by communication with the wireless communication device 2 based on the transmission value table 13A. Update as.

  The transmission output table management unit 12C calculates an appropriate minimum transmission power value based on the RSSI value and the S / N ratio value obtained by communication with the wireless communication device 2, and transmits the calculated power value. It may be updated to the output table 13A.

  Thus, only when both the RSSI and S / N ratio threshold values exceed the threshold values as the transmission power value update determination criteria, the transmission power table management unit 12C newly calculates the transmission power value of the transmission output table 13A. By updating to an appropriate and minimum transmission power value, power consumption can be reduced without causing packet loss.

  In addition, the wireless communication device according to the present invention reduces the power at the time of transmission output when the communication quality exceeds both the RSSI and S / N ratio thresholds, thereby causing radio wave interference to other wireless networks. This is effective in that it can be avoided.

  Also, if either RSSI or S / N ratio exceeds the threshold value, the transmission power value is not updated to a smaller value. In this case, the S / N ratio is sufficient even if RSSI is sufficient in a noisy environment. This is because there is a possibility that packet loss may occur and packet loss occurs, and in such a case, the value should not be updated to a smaller value.

  That is, the wireless communication device of the present invention can be reached at the transmission power value of the transmission output table 13A if the calculated RSSI relating to the wireless communication between the wireless communication devices 1 and 2 exceeds the RSSI threshold stored in advance. If the communication distance between the wireless communication apparatuses 1 and 2 is determined to be short compared to a short communication distance and the calculated S / N ratio related to the wireless communication exceeds the threshold value of the S / N ratio stored in advance, the transmission output Since it is determined that the wireless communication can be reliably performed even with the noise level between the wireless communication apparatuses 1 and 2 based on the transmission power value of the table 13A, the appropriate and minimum (minimum) according to the communication quality acquired together with the data transmission. By updating to the transmission power value, power consumption can be reduced without causing packet loss.

  Further, the power used for transmitting wireless data by the wireless communication means 14 of the wireless communication device 1 is generally considered to use a predetermined transmission power when transmitting to any wireless communication device. According to the wireless communication device according to the present invention, the transmission power can be reduced according to each communication quality between the plurality of wireless communication devices, so that the power consumption can be reduced according to each wireless communication than before. Power can be saved effectively.

  Note that the wireless communication device according to the present invention is configured so that when the communication quality related to wireless communication between other wireless communication devices exceeds the threshold values of both RSSI and S / N ratio in step SP107 described above, Although it is described that the transmission power is updated to be lower, the present invention is not particularly limited to this, and the storage means holds the RSSI and the lower limit threshold value of the S / N ratio in advance, and the transmission output table management means 12C performs other wireless communication. When the communication quality related to wireless communication between devices is both RSSI and / or the S / N ratio threshold value, or one of them falls below this lower threshold value, the transmission power in the transmission output table is updated to a higher value. There may be.

  As a result, the wireless communication apparatus according to the present invention checks the RSSI and the S / N ratio value every time data is transmitted, and updates the transmission power of the transmission output table lower or higher according to the communication quality. Thus, even when radio wave propagation and the communication environment change over time, it is effective in that communication can be performed with appropriate power consumption corresponding to the time change.

  FIG. 3 is an explanatory diagram of the effect of the present invention. In FIG. 3, the power saving of the power consumption in the wireless communication apparatus 1 will be described. 3, wireless communication between the wireless communication device 1, the wireless communication device 2, and a wireless communication device 3 (not shown) will be described. The wireless communication devices 2 and 3 have the same configuration as the wireless communication device 1 of FIG.

  The transmission power in periods A101 and A102 in which the active mode is operating (hereinafter referred to as the active period) represents the transmission power of the wireless communication apparatus 1 related to the wireless communication with the wireless communication apparatus 2. The transmission power in the active periods A103 and A104 represents the transmission power of the wireless communication device 1 related to wireless communication with the wireless communication device 3.

  In the active period A101, the wireless communication device 1 performs the same processing as the above-described step SP101 and performs wireless communication with the wireless communication device 2. Also, the wireless communication device 1 performs transmission power related to communication with the wireless communication device 2 in the transmission output table 13A when the communication quality exceeds both the threshold of RSSI and the S / N ratio by the same processing as step SP107. Is updated to a lower power value.

  In the active period A102, the wireless communication device 1 performs wireless communication with the wireless communication device 2 that transmits data through the wireless line with power corresponding to the updated transmission power value stored in the transmission output table 13A.

  Therefore, as shown in FIG. 3, the transmission power consumed in the active period A102 is less than the power used in the active period A101, and the power consumption is reduced.

  On the other hand, in the active period A103, the wireless communication device 1 performs the same processing as the above-described step SP101 and performs wireless communication with the wireless communication device 3. Also, the wireless communication device 1 performs transmission power related to communication with the wireless communication device 3 in the transmission output table 13A when the communication quality exceeds both the threshold value of RSSI and the S / N ratio by the same process as in step SP107. Is updated to a lower power value.

  In the active period A104, the wireless communication device 1 performs wireless communication with the wireless communication device 3 that transmits data through the wireless line with power corresponding to the updated transmission power value stored in the transmission output table 13A.

  Therefore, as shown in FIG. 3, the transmission power consumed in the active period A104 is less than the power used in the active period A103, and the power consumption is reduced.

  As a result, the wireless communication device according to the present invention measures communication quality related to wireless communication between other wireless communication devices, and both the RSSI and S / N ratio threshold values stored in advance are stored as threshold values. By exceeding the transmission power and transmitting at a lower transmission power, it is possible to provide a greater power saving effect than before without causing packet loss.

  In addition, the wireless communication apparatus according to the present invention reduces the transmission power in the transmission output table when the communication quality exceeds both the RSSI and S / N ratio thresholds, thereby communicating with the wireless communication apparatus having a short communication distance. In this case, communication is performed with lower transmission power, and unnecessary power consumption can be saved. In such an environment, even if the communication duty ratio is high, it is possible to reduce the power consumption as compared with the conventional means.

  In addition, the wireless communication device according to the present invention can be reached at the transmission power value of the transmission output table 13A if the calculated RSSI related to the wireless communication between other wireless communication devices exceeds the RSSI threshold stored in advance. If it is determined that the communication distance with other wireless communication devices is shorter than the communication distance, and the calculated S / N ratio related to the wireless communication exceeds the threshold of the S / N ratio stored in advance, the transmission output table Since it is determined that wireless communication can be reliably performed even with a noise level between other wireless communication devices with a transmission power value of 13A, the power value in the transmission output table is appropriate according to the communication quality acquired together with the data transmission. By updating to the minimum transmission power value, power consumption can be reduced without causing packet loss.

  In the wireless communication apparatus according to the present invention, the transmitter can check the RSSI and the S / N ratio every time data is transmitted. Therefore, even when the radio wave propagation and the communication environment change over time, the transmitter changes over time. Communication is possible with the appropriate minimum output.

  In addition, the wireless communication device according to the present invention reduces the power at the time of transmission output when the communication quality exceeds both the RSSI and S / N ratio thresholds, thereby causing radio wave interference to other wireless networks. This is effective in that it can be avoided.

It is a block diagram which shows the structural example of the radio | wireless communication apparatus which concerns on this invention. It is explanatory drawing of operation | movement at the time of radio | wireless communication of the radio | wireless communication apparatus of this invention. It is explanatory drawing of the effect of the radio | wireless communication apparatus of this invention. It is a block diagram which shows the structural example of the conventional radio | wireless communication apparatus. It is explanatory drawing of the transmission power in the sleep mode of the conventional radio | wireless communication apparatus, and active mode.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 2 Wireless communication apparatus 11 Communication means 12 Computation control part 12A Transmission output control means 12B Communication quality calculation means 12C Transmission output table management means 13 Storage means 13A Transmission output table 14 Wireless communication means 15 Wireless antenna

Claims (5)

A wireless communication unit having a function of measuring an RSSI value and a noise level at the time of wireless communication, and a sleep mode in which at least a part of the function of the wireless communication unit is stopped and active to execute the wireless communication by operating the wireless communication unit A wireless communication device for switching modes,
When the S / N ratio calculated from the RSSI value and the noise level and the RSSI value are both larger than the S / N ratio and the RSSI value threshold stored in advance, the wireless communication means is controlled. A wireless communication apparatus comprising an arithmetic control unit that performs wireless communication with smaller transmission power. The arithmetic control unit includes communication quality calculation means for calculating an S / N ratio based on the RSSI value and the noise level;
A transmission output table in which a transmission power value necessary for data transmission to another wireless communication device via a wireless line is stored corresponding to the identification information of the wireless communication device;
Storage means for storing the transmission output table, the RSSI value and a threshold of the S / N ratio;
When both the RSSI value and the S / N ratio are larger than the respective threshold values, transmission output table management means for changing the transmission power value of the transmission output table to a smaller value;
Transmission output control means for controlling the wireless communication means and transmitting data to a transmission destination wireless communication apparatus at a power corresponding to the transmission power value corresponding to the wireless communication apparatus in the transmission output table. The wireless communication apparatus according to claim 1. The wireless communication means includes
While receiving data from another wireless communication device via a wireless line, the RSSI value and noise level at the time of the wireless communication are measured, and communication quality data including these RSSI value and noise level is the transmission source of the data The wireless communication apparatus according to claim 1, wherein the wireless communication apparatus transmits to the wireless communication apparatus. The communication quality calculating means includes
4. The wireless communication apparatus according to claim 1, wherein an S / N ratio is calculated based on communication quality data received from the other wireless communication apparatus. A communication means for transmitting / receiving data to / from a field device via a wired line;
The wireless communication apparatus according to claim 1, further comprising: the wireless communication unit that transmits and receives data received from a field device via the communication unit via a wireless line.

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