JP2020155955A - Wireless communication device - Google Patents

Abstract

To provide a wireless communication device that can reduce power consumption more than before regardless of communication frequency.SOLUTION: A wireless communication device includes: a first wireless communication unit that performs wireless communication by using a frequency band that does not require a radio station license; and a control unit that controls switching between a first operation mode in which the first wireless communication unit is made to transmit data after confirming the availability of a channel to be used for data transmission in advance and a second operation mode in which the first wireless communication unit is made to transmit data without confirmation in advance.SELECTED DRAWING: Figure 2

Description

The present invention relates to a wireless communication device.

In recent years, technologies such as IoT (Internet of Things) and AI (Artificial Intelligence) have been attracting attention. IoT is a technology that connects all kinds of things (general hardware terminals such as sensors, devices and devices) to the Internet, grasps the state of things using data obtained from things, and operates things. AI is generally a technique for artificially reproducing human intellectual behavior by software, for example, a technique for understanding natural language used by humans, logical reasoning, and the like.

In recent years, efforts have been made to use such IoT and AI to construct a system that catches signs of abnormalities in equipment installed in factories, plants, etc. and prevents equipment failures. Specifically, in this system, a large number of wireless sensors are installed in the target equipment, and a server device that collects various data transmitted by wireless signals from the wireless sensors is provided, and the data accumulated in the server device is collected. It is a system that analyzes and catches the signs of the above-mentioned abnormality.

In such a system, wireless communication by the above-mentioned wireless sensor is often performed using a frequency band (unlicensed band) that does not require a wireless station license. Further, since the above-mentioned wireless sensor may be installed in a place where it is difficult to secure a power source, battery drive is required. Such a battery-powered wireless sensor is required to have low power consumption in order to extend the battery life. The following Patent Document 1 discloses an example of a conventional technique for suppressing an increase in power consumption in a wireless communication device that controls a race condition of a plurality of communication systems by using a carrier sense method.

Japanese Patent No. 6288268

By the way, most of the wireless communication devices used in the system for catching the above-mentioned signs of abnormality perform wireless communication at a low frequency (for example, a frequency of several hours to once a day). This wireless communication device temporarily has a high frequency (for example, once every few minutes to several hours) in order to measure more detailed data when the above-mentioned signs of abnormality are detected. The settings may be changed to send data. In a wireless communication device whose communication frequency is changed in this way, in order to extend the battery life, unnecessary power consumption when wireless communication is performed at low frequency is suppressed, and when wireless communication is performed at high frequency. It is necessary to reduce unnecessary power consumption.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a wireless communication device capable of suppressing power consumption as compared with the conventional case regardless of the communication frequency.

In order to solve the above problems, the wireless communication device (10) according to one aspect of the present invention includes a first wireless communication unit (13) that performs wireless communication using a frequency band that does not require a wireless station license, and data. The first operation mode in which the availability of the channel used for transmission is confirmed in advance and then the data is transmitted to the first wireless communication unit, and the data is transmitted to the first wireless communication unit without the prior confirmation. It is provided with a control unit (15) that controls switching to the second operation mode.

Further, in the wireless communication device according to one aspect of the present invention, the control unit has the first operation mode and the second operation mode according to at least one of a data transmission cycle, a communication data rate, and an error rate. Perform switching control.

Further, in the wireless communication device according to one aspect of the present invention, when the control unit has the data transmission cycle equal to or less than the predetermined first threshold value, the communication data rate is equal to or less than the predetermined second threshold value. In this case, or when the error rate is larger than a predetermined third threshold value, control is performed to switch to the first operation mode.

Further, the wireless communication device according to one aspect of the present invention includes a storage unit (12) for storing setting information (CD) used for switching control between the first operation mode and the second operation mode. The control unit performs switching control between the first operation mode and the second operation mode based on the setting information stored in the storage unit.

Further, the wireless communication device according to one aspect of the present invention further includes a second wireless communication unit (14) that performs short-range wireless communication with an external device (TM) to acquire the setting information.

Further, the wireless communication device according to one aspect of the present invention can execute the first data transmission cycle capable of executing the first operation mode and the second operation mode in the setting information. A first table (TB1) in which a second data transmission cycle is defined is included, and the first data transmission cycle includes the data transmission cycle below the first threshold value and more than the first threshold value. The large data transmission cycle can be set, and only the data transmission cycle larger than the first threshold value can be set in the second data transmission cycle.

Alternatively, the wireless communication device according to one aspect of the present invention can execute the first communication data rate capable of executing the first operation mode and the second operation mode in the setting information. A second table (TB2) in which a second communication data rate is defined is included, and the first communication data rate includes the communication data rate equal to or lower than the second threshold value and higher than the second threshold value. The communication data rate that is large can be set, and only the communication data rate that is larger than the second threshold value can be set in the second communication data rate.

Alternatively, in the wireless communication device according to one aspect of the present invention, the setting information includes at least one of the first threshold value, the second threshold value, and the third threshold value, and the control unit uses the data. When the transmission cycle is equal to or less than the first threshold value, the communication data rate is equal to or less than the second threshold value, or the error rate is larger than the third threshold value, the first operation mode is set. When the data transmission cycle is larger than the first threshold value, the communication data rate is larger than the second threshold value, or the error rate is equal to or lower than the third threshold value. Is controlled to be in the second operation mode.

Further, the wireless communication device according to one aspect of the present invention includes at least a battery (BT) for supplying electric power to the first wireless communication unit and the control unit.

Further, in the wireless communication device according to one aspect of the present invention, the battery is replaceable.

According to the present invention, there is an effect that power consumption can be suppressed as compared with the conventional case regardless of the communication frequency.

It is a figure which shows the whole structure of the data acquisition system which uses the wireless communication apparatus by 1st Embodiment of this invention. It is a block diagram which shows the main part structure of the wireless communication apparatus by 1st Embodiment of this invention. It is a figure which shows the table used for the switching control of the operation mode in 1st Embodiment of this invention. It is a flowchart which shows an example of the operation of the wireless communication apparatus by 1st Embodiment of this invention. It is a flowchart which shows an example of the operation in the modification of 1st Embodiment of this invention. It is a figure which shows the operation mode set in the modification of 1st Embodiment of this invention. It is a figure which shows the table used for the switching control of the operation mode in the 2nd Embodiment of this invention. It is a figure which shows the operation mode set in the modification of the 2nd Embodiment of this invention. It is a figure which shows the operation mode set in the 3rd Embodiment of this invention. It is a flowchart which shows an example of the operation in 4th Embodiment of this invention.

Hereinafter, the wireless communication device according to the embodiment of the present invention will be described in detail with reference to the drawings. Hereinafter, the outline of the embodiment of the present invention will be described first, and then the details of each embodiment of the present invention will be described.

〔Overview〕
An embodiment of the present invention makes it possible to reduce power consumption as compared with the conventional case regardless of the communication frequency. Here, there are the following two methods for a wireless communication device that performs wireless communication using a frequency band (unlicensed band) that does not require a wireless station license to access a channel (radio channel).

・ LBT (Listen Before Talk)
This is a method of transmitting data after confirming the availability of the channel used for data transmission in advance. Specifically, the reception level in the channel to be used (for example, the channel of the frequency used for transmission) is detected before the data is transmitted. If the detected reception level is higher than a predetermined threshold, it is determined that the channel is in use and data is not transmitted. On the other hand, when the detected reception level is equal to or lower than the above threshold value, it is determined that the channel is vacant and data transmission is performed. This method is sometimes called CCA (Clear Channel Assessment).

・ DC (Duty Cycle)
This is a method of operating with a limit (legal limit) on the ratio of the transmission time of the wireless communication device to a certain period. In this method, data is transmitted without prior confirmation such as LBT.

Wireless communication devices that perform wireless communication using unlicensed bands shall, according to the laws of the country or region in which they are used, carry out the above LBT before transmitting data, or operate in accordance with the above DC restrictions. You may be required to do so.

By the way, the wireless communication device that carries out the above-mentioned LBT before transmitting the data confirms whether or not the channel used for transmitting the data is a free channel before transmitting the data. Therefore, for example, even in a situation where another radio station frequently transmits data (for example, once every few minutes to several hours) and there is a high possibility of interfering with the other radio station. Reliable wireless communication is possible using free channels.

However, in the wireless communication device that performs the above-mentioned LBT before transmitting data, for example, another wireless station transmits data at a low frequency (for example, a frequency of several hours to once a day). Even in situations where it is unlikely to interfere with other radio stations, the above LBT is performed before data transmission. Therefore, unnecessary power consumption is generated, which causes a shortening of battery life.

On the other hand, in the wireless communication device operated according to the above-mentioned DC limitation, the above-mentioned LBT is not performed regardless of the communication frequency. Therefore, in a situation where wireless communication is performed at low frequency, unnecessary power consumption does not occur, so that the battery life can be extended as compared with the wireless communication device that performs the above-mentioned LBT before data transmission.

However, in a wireless communication device operated in accordance with the above-mentioned DC limitation, the above-mentioned LBT is not performed. Therefore, in a situation where wireless communication is performed frequently, data communication loss due to radio wave interference with other wireless stations is lost. Is likely to occur. Then, the retransmission process is frequently performed, which wastes power and shortens the battery life. Also, when transmitting data at a low data rate or when transmitting data with a large data size, the transmission time will be long, but due to DC regulations, it is not possible to transmit data as often as you want. Can be considered. Further, even if the data can be transmitted, the transmission time is long, which causes an increase in power consumption and a shortening of the battery life.

In the embodiment of the present invention, in the case of wireless communication using the unlicensed band, the first operation mode in which the data is transmitted after confirming the availability of the channel used for data transmission in advance and the prior confirmation are performed. Switching control with the second operation mode in which data is transmitted without performing is performed. Specifically, switching control between the first operation mode and the second operation mode is performed according to at least one of a data transmission cycle, a communication data rate, and an error rate. As a result, communication loss when wireless communication is performed at high frequency can be suppressed, and unnecessary power consumption can be suppressed by reducing retransmission processing (or eliminating retransmission processing). Further, since unnecessary power consumption can be suppressed when wireless communication is performed at a low frequency, power consumption can be suppressed as compared with the conventional case regardless of the communication frequency.

[First Embodiment]
<Data collection system>
FIG. 1 is a diagram showing an overall configuration of a data collection system in which the wireless communication device according to the first embodiment of the present invention is used. As shown in FIG. 1, the data collection system 1 includes a wireless sensor 10 (wireless communication device), a gateway 20, and a server 30, and various data transmitted by wireless signals from the wireless sensor 10 are transmitted to the gateway 20. It collects data on the server 30 via the server 30.

The wireless sensor 10 is installed in the equipment FC to be measured and measures various physical quantities (for example, temperature, humidity, pressure, vibration, magnetism, corrosion, etc.). The wireless sensor 10 is connected to the gateway 20 via the wireless network N1. The wireless sensor 10 transmits the measurement results of various physical quantities to the gateway 20 via the wireless network N1. The wireless network N1 is, for example, a communication path (LPWAN: Low Power Wide Area Network) capable of low power consumption long-distance wireless communication. The wireless sensor 10 can also perform short-range wireless communication with the terminal device TM (external device). Details of the wireless sensor 10 will be described later.

The equipment FC to be measured in which the wireless sensor 10 is installed may be, for example, any equipment (including equipment and devices) installed in the plant. The above plants include industrial plants such as chemicals, plants that manage and control wells such as gas fields and oil fields and their surroundings, plants that manage and control power generation such as hydropower, thermal power, and nuclear power, solar power, wind power, etc. It may be a plant that manages and controls environmental power generation, a plant that manages and controls water and sewage, dams, and the like.

The gateway 20 connects the wireless network N1 and the network N2, and relays various data transmitted / received via the wireless network N1 and various data transmitted / received via the network N2. By providing the gateway 20, the wireless network N1 and the network N2 can be connected to each other while maintaining security. The gateway 20 is installed at an arbitrary place where the wireless signal transmitted from the wireless sensor 10 can be received. The installation location of the gateway 20 may be inside the plant or outside the plant.

The server 30 collects and stores data from the wireless sensor 10 transmitted via the gateway 20. The server 30 may analyze the accumulated data to catch signs of abnormality in the equipment FC to be measured. The server 30 is connected to the gateway 20 via the network N2. The network N2 may be a WAN (Wide Area Network) such as the Internet, or may be a LAN (Local Area Network) laid in a plant or the like.

<Wireless communication device>
FIG. 2 is a block diagram showing a main configuration of a wireless communication device according to the first embodiment of the present invention. As shown in FIG. 2, the wireless sensor 10 as a wireless communication device according to the present embodiment includes a sensor unit 11, a storage unit 12, a wireless communication unit 13 (first wireless communication unit), and a wireless communication unit 14 (second wireless communication unit). ), A control unit 15, a power supply unit 16, and antennas AT1 and AT2. The wireless sensor 10 measures the various physical quantities described above and transmits the measurement results at a predetermined periodic cycle.

The sensor unit 11 includes a sensor for detecting various physical quantities described above (for example, a temperature sensor, a humidity sensor, a pressure sensor, a vibration sensor, a magnetic sensor, a corrosion sensor, etc.) and a sampling circuit for sampling the detection result of the sensor. The sensor unit 11 detects and samples various physical quantities under the control of the control unit 15. The sampling data sampled by the sampling circuit is output from the sensor unit 11 to the control unit 15 as sensor data.

The storage unit 12 stores various data used by the wireless sensor 10. For example, the storage unit 12 stores a setting data CD that defines the operation of the wireless sensor 10. The storage unit 12 may store the sensor data output from the sensor unit 11 to the control unit 15. The storage unit 12 is realized, for example, by a volatile or non-volatile memory. The details of the setting data CD will be described later.

The wireless communication unit 13 performs wireless communication via the wireless network N1 under the control of the control unit 15. The wireless communication performed by the wireless communication unit 13 via the wireless network N1 is wireless communication using a frequency band (unlicensed band) that does not require a wireless station license. The wireless communication unit 13 performs wireless communication conforming to a communication standard such as LoRa (registered trademark), which is a kind of low power consumption long-distance wireless communication described above. The antenna AT1 is connected to the wireless communication unit 13. As the antenna AT1, for example, a chip antenna element can be used. When the wireless communication unit 13 is designed so that the transmission data path and the reception data path are different, a switch for switching the route between the wireless communication unit 13 and the antenna AT1 is provided. Is also good.

The wireless communication unit 14 performs short-range wireless communication with the terminal device TM, which is an external device. The short-range wireless communication performed by the wireless communication unit 14 may be Wi-Fi (registered trademark), ZigBee (registered trademark), Bluetooth (registered trademark), NFC (Near Field Communication) or the like. Further, the short-range wireless communication performed by the wireless communication unit 14 may be infrared communication. The wireless communication unit 14 performs short-range wireless communication with the terminal device TM to acquire a setting data CD that defines the operation of the wireless sensor 10. The antenna AT2 is connected to the wireless communication unit 14. As the antenna AT2, for example, a loop antenna can be used. When the wireless communication unit 14 is designed so that the transmission data path and the reception data path are different, a switch for switching the route between the wireless communication unit 14 and the antenna AT2 is provided. Is also good.

The control unit 15 controls the wireless sensor 10 by controlling each unit (sensor unit 11, storage unit 12, wireless communication unit 13, wireless communication unit 14, and power supply unit 16) of the wireless sensor 10. For example, the control unit 15 controls the sensor unit 11 to detect various physical quantities at a predetermined fixed cycle, performs predetermined processing on the obtained sensor data to obtain various physical quantities, and obtains various physical quantities, and obtains various physical quantities. 13 is controlled to transmit data indicating various physical quantities.

Here, when the control unit 15 controls the wireless communication unit 13 to transmit data, the control unit 15 performs prior confirmation (LBT) of the availability of the channel used for data transmission, and then transmits the data to the wireless communication unit 13. Switching control is performed between an operation mode for transmitting data (mode with LBT: first operation mode) and an operation mode for transmitting data to the wireless communication unit 13 (mode without LBT) without performing the above-mentioned prior confirmation (LBT). The control unit 15 performs such operation mode switching control in order to reduce power consumption as compared with the conventional case regardless of the communication frequency. For example, in the case of the LBT non-mode, the transmission may be performed by a DC method.

The control unit 15 performs the above-mentioned operation mode switching control according to the data transmission cycle. Specifically, when the data transmission cycle is equal to or less than a preset first threshold value (for example, 180 [minutes]), the control unit 15 controls to set the mode with LBT. The reason for performing such control is to suppress communication loss when wireless communication is performed frequently, and to suppress wasteful power consumption due to frequent retransmission processing. The first threshold value is set in consideration of the above-mentioned DC regulation.

The control unit 15 performs the operation mode switching control described above based on the setting data CD stored in the storage unit 12. Specifically, the control unit 15 performs the above-described operation mode switching control using the table TB1 (first table) shown in FIG. 3 stored in the storage unit 12 as the setting data CD. FIG. 3 is a diagram showing a table used for operation mode switching control in the first embodiment of the present invention. The table TB1 shown in FIG. 3 is created by the terminal device TM, and is acquired by the wireless communication unit 14 and stored in the storage unit 12 by performing short-range wireless communication between the wireless communication unit 14 and the terminal device TM. It is stored as a setting data CD.

The table TB1 defines a data transmission cycle (first data transmission cycle) capable of executing the mode with LBT and a data transmission cycle (second data transmission cycle) capable of executing the mode without LBT. It is a table that has been created. In the example shown in FIG. 3, 1 [minute] to 4320 [minute] are defined as the data transmission cycle in which the mode with LBT can be executed (settable), and the mode without LBT can be executed. 240 [minutes] to 4320 [minutes] are specified as the (settable) data transmission cycle.

Specifically, as the data transmission cycle that can execute (settable) the mode with LBT, 1 [minute], 10 [minute], 30 [minute], 60 [minute], 120 [minute], 180 [ Minutes], 240 [minutes], 300 [minutes], 360 [minutes], 720 [minutes], 1080 [minutes], 1440 [minutes] (1 day), 2880 [minutes] (2 days), 4320 [minutes] (3 days) is stipulated. The data transmission cycle that can execute (settable) the LBT non-mode is 240 [minutes], 300 [minutes], 360 [minutes], 720 [minutes], 1080 [minutes], 1440 [minutes] (1). Days), 2880 [minutes] (2 days), 4320 [minutes] (3 days) are specified.

In the example shown in FIG. 3, when the data transmission cycle is 1 [minute] to 180 [minute], it is impossible (cannot be set) to execute the LBT no mode. That is, in the example shown in FIG. 3, the above-mentioned first threshold value is set to 180 [minutes]. The data transmission cycle in which the LBT presence mode can be executed includes a data transmission cycle (1 [minute] to 180 [minute]) below the first threshold value and a data transmission cycle (240] that is larger than the first threshold value. [Minute] to 4320 [minute]) can be set.

On the other hand, only the data transmission cycle (240 [minutes] to 4320 [minutes]), which is larger than the first threshold value, can be set as the data transmission cycle in which the LBT non-mode can be executed. By doing so, when the data transmission cycle is 180 [minutes] or less (when it is 1 [minutes] to 180 [minutes]), the mode with LBT is executed.

Here, when the data transmission cycle is larger than 180 [minutes] (when it is 240 [minutes] to 4320 [minutes]), it is possible to execute both the mode with LBT and the mode without LBT. is there. Therefore, when the data transmission cycle is larger than 180 [minutes], the control unit 15 performs operation mode switching control according to the setting contents of the table TB1. For example, when the data transmission cycle is larger than 180 [minutes], it is desirable to set the table TB1 so that only the LBT no mode is executed. By setting in this way, when wireless communication is performed at a low frequency, LBT is not executed, and unnecessary power consumption due to the implementation of LBT can be suppressed.

The power supply unit 16 includes a battery BT, and under the control of the control unit 15, each unit of the wireless sensor 10 (sensor unit 11, storage unit 12, wireless communication unit 13, wireless communication unit 14, and control unit 15). Power is supplied to. The power supply unit 16 is configured so that the battery BT can be replaced. As the battery BT, for example, a primary battery such as a lithium thionyl chloride battery, a secondary battery, a fuel cell, or the like with extremely low self-discharge can be used.

When the control unit 15 outputs a control signal instructing the power saving operation, the power supply unit 16 may, for example, other than the control unit 15 (sensor unit 11, storage unit 12, wireless communication) in order to suppress the consumption of the battery BT. The power supply to the unit 13 and the wireless communication unit 14) is stopped. When the control unit 15 outputs a control signal instructing the cancellation of the power saving operation, the power supply unit 16 is, for example, other than the control unit 15 (sensor unit 11, storage unit 12, wireless communication unit 13, and wireless communication unit). The power supply to 14) is restarted.

<Operation of wireless communication device>
FIG. 4 is a flowchart showing an example of the operation of the wireless communication device according to the first embodiment of the present invention. In addition, the flowchart shown in FIG. 4 shows only the operation at the time of data transmission. The flowchart shown in FIG. 4 is repeated at a preset constant cycle.

When the processing of the flowchart shown in FIG. 4 is started, the control unit 15 first reads the table TB1 stored as the setting data CD in the storage unit 12 (step S11). Next, the control unit 15 performs a process of setting the operation mode according to the setting contents of the table TB1 (step S12). For example, when the data transmission cycle is equal to or less than the first threshold value (when it is 1 [minute] to 180 [minute]), the control unit performs a process of setting the LBT present mode according to the setting contents of the table TB1 shown in FIG. It is done by 15.

When the data transmission cycle is larger than the first threshold value (240 [minutes] to 4320 [minutes]), the mode is set to either the LBT presence mode or the LBT non-mode according to the setting contents of the table TB1. The process of setting is performed by the control unit 15. For example, in the table TB1 shown in FIG. 3, a data transmission cycle (240 [minutes] to 4320 [minutes]) larger than the first threshold value is set as a data transmission cycle capable of executing the LBT presence mode. If the data transmission cycle is set so that the LBT-free mode can be executed, the control unit 15 performs the process of setting the LBT-free mode.

When the above setting is completed, the wireless communication unit 13 is controlled by the control unit 15 to execute the data transmission process (step S13). Specifically, when the mode with LBT is set in the process of step S12, the process of transmitting data after performing LBT is performed. On the other hand, when the LBT no mode is set in the process of step S12, the process of transmitting data is performed without performing LBT.

<Modification example>
Next, a modified example of the first embodiment of the present invention will be described. In this modification, instead of storing the table TB1 shown in FIG. 3 as the setting data CD in the storage unit 12, the above-mentioned first threshold value (180 [minutes]) is stored in the storage unit 12 as the setting data CD. .. Then, the operation mode switching control is performed based on the comparison result between the data transmission cycle and the first threshold value.

FIG. 5 is a flowchart showing an example of the operation in the modified example of the first embodiment of the present invention. FIG. 6 is a diagram showing an operation mode set in a modified example of the first embodiment of the present invention. Note that the flowchart shown in FIG. 5 is the same as the flowchart shown in FIG. 4, in which only the operation at the time of data transmission is extracted and shown, and is repeated at a preset constant cycle.

When the process of the flowchart shown in FIG. 5 is started, the control unit 15 first performs a process of determining whether or not the data transmission cycle is equal to or less than the first threshold value (step S21). When it is determined that the data transmission cycle is equal to or less than the first threshold value (when the determination result is "YES"), the control unit 15 performs a process of setting the LBT present mode (step S22). That is, when the data transmission cycle is 1 [minute] to 180 [minute], the mode with LBT is set as shown in FIG.

On the other hand, when it is determined that the data transmission cycle is larger than the first threshold value (when the determination result is "NO"), the control unit 15 performs a process of setting the LBT non-mode (step S23). ). That is, when the data transmission cycle is 240 [minutes] to 4320 [minutes], the LBT non-mode is set as shown in FIG.

When the above settings are completed, the wireless communication unit 13 is controlled by the control unit 15 to perform data transmission processing (step S24). Specifically, when the mode with LBT is set in the process of step S22, the process of transmitting data after performing LBT is performed. On the other hand, when the LBT no mode is set in the process of step S23, the process of transmitting data is performed without performing LBT.

As described above, in the present embodiment, when wireless communication is performed using the unlicensed band, based on the data transmission cycle and the setting contents of the table TB1 (or the comparison result between the data transmission cycle and the first threshold value) Based on this), switching control between the mode with LBT and the mode without LBT is performed. Thereby, for example, when wireless communication is performed frequently, LBT can be performed, and wasteful power consumption due to frequent retransmission processing can be suppressed. Further, when wireless communication is performed at a low frequency, it is possible to prevent the LBT from being carried out and suppress unnecessary power consumption due to the LBT being carried out. As a result, the power consumption can be suppressed as compared with the conventional case, and the life of the battery BT (battery life) can be extended.

[Second Embodiment]
Next, the second embodiment of the present invention will be described. The wireless sensor 10 as the wireless communication device of the first embodiment described above performs operation mode switching control according to a data transmission cycle. On the other hand, the wireless sensor as the wireless communication device of the present embodiment controls the switching of the operation mode according to the communication data rate.

The wireless sensor of the present embodiment is different from the wireless sensor 10 of the first embodiment only in that the operation mode switching control is performed according to the communication data rate, and the wireless sensor of the first embodiment is shown in FIG. It has the same configuration as the wireless sensor 10 of the above. Further, the wireless sensor in this embodiment can be used in the data acquisition system 1 in the same manner as the wireless sensor 10 shown in FIG.

When the communication data rate is equal to or less than a preset second threshold value (for example, 1760 [bps]), the control unit 15 included in the wireless sensor of the present embodiment controls the mode with LBT. The reason for performing such control is to suppress communication loss when wireless communication is performed frequently, and to suppress wasteful power consumption due to frequent retransmission processing. Here, in the present embodiment, when the communication data rate becomes small (for example, becomes equal to or less than the second threshold value), the data transmission time becomes long and the ratio of the transmission time to the predetermined time increases, so that the frequency is high. Wireless communication will be performed. As with the first threshold value, the second threshold value is set in consideration of the above-mentioned DC regulation.

FIG. 7 is a diagram showing a table used for operation mode switching control in the second embodiment of the present invention. The table TB2 shown in FIG. 7 is created by the terminal device TM in the same manner as the table TB1 shown in FIG. 3, and wireless communication is performed by performing short-range wireless communication between the wireless communication unit 14 and the terminal device TM. It is acquired by the unit 14 and stored in the storage unit 12 as a setting data CD.

Table TB2 defines a communication data rate (first communication data rate) capable of executing the mode with LBT and a communication data rate (second communication data rate) capable of executing the mode without LBT. It is a table that has been created. In the example shown in FIG. 7, 250 [bps] to 50,000 [bps] are specified as the communication data rates that can execute (settable) the mode with LBT, and the mode without LBT can be executed. As a (configurable) communication data rate, 3125 [bps] to 50,000 [bps] are specified.

Specifically, as communication data rates that can (settable) execute the mode with LBT, 250 [bps], 440 [bps], 980 [bps], 1760 [bps], 3125 [bps], 5470 [ bps], 11000 [bps], and 50000 [bps] are specified. 3125 [bps], 5470 [bps], 11000 [bps], and 50000 [bps] are specified as communication data rates that can (settable) execute the LBT-free mode.

In the example shown in FIG. 7, when the communication data rate is 250 [bps] to 1760 [bps], it is impossible (cannot be set) to execute the LBT no mode. That is, in the example shown in FIG. 7, the above-mentioned second threshold value is set to 1760 [bps]. Communication data rates capable of executing the LBT presence mode include communication data rates below the second threshold (250 [bps] to 1760 [bps]) and communication data rates greater than the second threshold (3125). [Bps] to 50,000 [bps]) can be set.

On the other hand, as the communication data rate capable of executing the LBT no mode, only the communication data rate (3125 [bps] to 50,000 [bps]) larger than the second threshold value can be set. By doing so, when the communication data rate is 1760 [bps] or less (250 [bps] to 1760 [bps]), the mode with LBT is executed.

Here, when the communication data rate is larger than 1760 [bps] (when it is 3125 [bps] to 50,000 [bps]), it is possible to execute both the mode with LBT and the mode without LBT. is there. Therefore, when the communication data rate is higher than 1760 [bps], the control unit 15 performs operation mode switching control according to the setting contents of the table TB2. For example, it is desirable to set the table TB2 so that only the LBT no mode is executed when the communication data rate is larger than 1760 [bps].

By setting in this way, when wireless communication is performed at a low frequency, LBT is not executed, and unnecessary power consumption due to the implementation of LBT can be suppressed. Here, in the present embodiment, when the communication data rate becomes large (for example, it becomes larger than the second threshold value), the data transmission time becomes short and the ratio of the transmission time to the predetermined time decreases, so that it is low. Wireless communication will be performed frequently.

In the wireless sensor of the present embodiment, at the time of data transmission, the same processing as the processing of the flowchart shown in FIG. 4 is performed. The flowchart showing the operation of the wireless sensor at the time of data transmission in the present embodiment is obtained by replacing "table TB1" in FIG. 4 with "table TB2". That is, in the present embodiment, first, the control unit 15 performs a process of reading out the table TB2 stored as the setting data CD in the storage unit 12 (step S11). Next, the control unit 15 performs a process of setting the operation mode according to the setting contents of the table TB2 (step S12). Then, the wireless communication unit 13 is controlled by the control unit 15, and the data transmission process is executed (step S13).

<Modification example>
Also in this embodiment, the same modification as in the first embodiment is possible. That is, instead of storing the table TB2 shown in FIG. 7 as the setting data CD in the storage unit 12, the above-mentioned second threshold value (1760 [bps]) can be stored in the storage unit 12 as the setting data CD. In this modification, the same processing as that of the flowchart shown in FIG. 5 is performed. In the flowchart showing the operation of the wireless sensor during data transmission in this modification, "is the data transmission cycle below the first threshold?" In step S21 in FIG. 5 is read as "is the communication data rate below the second threshold?" It is a thing.

That is, in this modification, first, the control unit 15 performs a process of determining whether or not the communication data rate is equal to or less than the second threshold value (step S21). When it is determined that the communication data rate is equal to or less than the second threshold value (when the determination result is "YES"), the control unit 15 performs a process of setting the LBT presence mode (step S22). That is, when the communication data rate is 250 [bps] to 1760 [bps], the mode with LBT is set as shown in FIG. FIG. 8 is a diagram showing an operation mode set in a modified example of the second embodiment of the present invention.

On the other hand, when it is determined that the communication data rate is larger than the second threshold value (when the determination result is "NO"), the control unit 15 performs a process of setting the LBT non-mode (step S23). ). That is, when the communication data rate is 3125 [bps] to 50,000 [bps], the LBT non-mode is set as shown in FIG.

When the above settings are completed, the wireless communication unit 13 is controlled by the control unit 15 to perform data transmission processing (step S24). Specifically, when the mode with LBT is set in the process of step S22, the process of transmitting data after performing LBT is performed. On the other hand, when the LBT no mode is set in the process of step S23, the process of transmitting data is performed without performing LBT.

As described above, in the present embodiment, when wireless communication is performed using the unlicensed band, based on the communication data rate and the setting contents of the table TB2 (or the comparison result between the communication data rate and the second threshold value). (Based on this), switching control between the mode with LBT and the mode without LBT is performed. As a result, as in the first embodiment, the power consumption can be suppressed as compared with the conventional case, and the life of the battery BT (battery life) can be extended.

[Third Embodiment]
Next, a third embodiment of the present invention will be described. The wireless sensor 10 as the wireless communication device of the first embodiment described above performs operation mode switching control according to a data transmission cycle. On the other hand, the wireless sensor as the wireless communication device of the present embodiment controls the switching of the operation mode according to the packet error rate (PER).

The wireless sensor of the present embodiment is different from the wireless sensor 10 of the first embodiment only in that the operation mode switching control is performed according to the packet error rate, and the wireless sensor of the first embodiment is shown in FIG. It has the same configuration as the wireless sensor 10 of the above. Further, the wireless sensor in this embodiment can be used in the data acquisition system 1 in the same manner as the wireless sensor 10 shown in FIG.

When the packet error rate is larger than a preset third threshold value (for example, 10 [%]), the control unit 15 included in the wireless sensor of the present embodiment controls to set the mode with LBT. .. Performing such control does not mean that the communication environment is good, and by suppressing communication loss in a situation where radio wave interference with other radio stations is likely to occur, wasteful power due to frequent retransmission processing is performed. This is to reduce consumption.

In the present embodiment, the above-mentioned third threshold value (10 [%]) is stored in the storage unit 12 as the setting data CD. In the present embodiment, after the process of calculating the packet error rate is performed, the same process as the process of the flowchart shown in FIG. 5 is performed. The flowchart showing the operation of the wireless sensor at the time of data transmission in the present embodiment shows "is the data transmission cycle equal to or less than the first threshold value?" In step S21 in FIG. 5, and "is the packet error rate larger than the third threshold value?" It was read as.

In the present embodiment, first, the wireless communication unit 13 is controlled by the control unit 15, and communication is performed between the wireless communication unit 13 and the gateway 20 for a certain period of time required for calculating a packet error. Then, the control unit 15 performs a process of calculating a packet error based on the communication result.

When the above processing is completed, the control unit 15 performs a process of determining whether or not the packet error rate is higher than the third threshold value (step S21). When it is determined that the packet error rate is larger than the third threshold value (when the determination result is "YES"), the control unit 15 performs the process of setting the LBT present mode as shown in FIG. 9 (when the determination result is "YES"). Step S22). FIG. 9 is a diagram showing an operation mode set in the third embodiment of the present invention.

On the other hand, when it is determined that the packet error rate is equal to or less than the third threshold value (when the determination result is "NO"), as shown in FIG. 9, the control unit 15 performs a process of setting the LBT non-mode. (Step S23). Such control is performed because the communication environment is good, radio wave interference is unlikely to occur, and communication loss is small (or almost nonexistent), so that it is considered that retransmission processing is small (or almost nonexistent). In the LBT-free mode, since LBT is not performed, unnecessary power consumption can be suppressed.

When the above settings are completed, the wireless communication unit 13 is controlled by the control unit 15 to perform data transmission processing (step S24). Specifically, when the mode with LBT is set in the process of step S22, the process of transmitting data after performing LBT is performed. On the other hand, when the LBT no mode is set in the process of step S23, the process of transmitting data is performed without performing LBT.

As described above, in the present embodiment, in the case of performing wireless communication using the unlicensed band, switching control between the mode with LBT and the mode without LBT is performed based on the comparison result between the packet error rate and the third threshold value. I am trying to do it. As a result, as in the first embodiment, the power consumption can be suppressed as compared with the conventional case, and the life of the battery BT (battery life) can be extended.

[Fourth Embodiment]
Next, a fourth embodiment of the present invention will be described. This embodiment is a combination of the above-described modification of the first embodiment and the third embodiment. FIG. 10 is a flowchart showing an example of the operation according to the fourth embodiment of the present invention. Note that the flowchart shown in FIG. 10 is the same as the flowchart shown in FIG. 5, in which only the operation at the time of data transmission is extracted and shown, and is repeated at a preset constant cycle.

When the process of the flowchart shown in FIG. 10 is started, the control unit 15 first performs a process of determining whether or not the data transmission cycle is equal to or less than the first threshold value (step S21). When it is determined that the data transmission cycle is equal to or less than the first threshold value (when the determination result is "YES"), the control unit 15 performs a process of setting the LBT present mode (step S22).

On the other hand, when it is determined that the data transmission cycle is larger than the first threshold value (when the judgment result is "NO"), it is determined whether or not the packet error rate is larger than the third threshold value. The processing to be performed is performed by the control unit 15 (step S31). When it is determined that the packet error rate is larger than the third threshold value (when the determination result is "YES"), the control unit 15 performs a process of setting the LBT present mode (step S22). On the other hand, when it is determined that the packet error rate is equal to or less than the third threshold value (when the determination result is "NO"), the control unit 15 performs a process of setting the LBT non-mode (step S23).

When the above settings are completed, the wireless communication unit 13 is controlled by the control unit 15 to perform data transmission processing (step S24). Specifically, when the mode with LBT is set in the process of step S22, the process of transmitting data after performing LBT is performed. On the other hand, when the LBT no mode is set in the process of step S23, the process of transmitting data is performed without performing LBT.

As described above, in the present embodiment, when wireless communication is performed using the unlicensed band, the comparison result between the data transmission cycle and the first threshold value and the comparison result between the packet error rate and the third threshold value are used. , Switching control between the mode with LBT and the mode without LBT is performed. As a result, switching control between the mode with LBT and the mode without LBT is performed while considering the communication frequency and the communication environment, so that the power consumption can be suppressed as compared with the conventional case, and the life of the battery BT (battery life) can be shortened. Can be extended.

In the present embodiment, when the packet error rate is close to the third threshold value, it is conceivable that the mode with LBT and the mode without LBT are frequently switched. Therefore, it is desirable to take measures so that the mode with LBT and the mode without LBT are not frequently switched. For example, when the packet error rate becomes larger than the third threshold value (10 [%]) (when the determination result in step S31 becomes “YES”), the packet error rate becomes a predetermined value (for example, 8). It is conceivable to take measures such as not switching between the mode with LBT and the mode without LBT until it becomes smaller than [%]). That is, a measure such as giving a hysteresis (for example, [2%]) to the third threshold value can be considered.

Although the wireless communication device according to the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment and can be freely changed within the scope of the present invention. For example, the above-described fourth embodiment is a combination of the modified example of the first embodiment and the third embodiment, but it is also possible to combine the modified example of the second embodiment and the third embodiment. Is. The flowchart showing the operation in this combination is obtained by replacing "data transmission cycle is equal to or less than the first threshold value?" In step S21 in FIG. 10 with "communication data rate is equal to or less than the second threshold value?".

It is also possible to combine the first embodiment and the second embodiment. In the flowchart showing the operation in this combination, "PER is larger than the third threshold value?" In step S31 in FIG. 10 is read as "communication data rate is equal to or less than the second threshold value?". Furthermore, it is also possible to combine the first to third embodiments. In the flowchart showing the operation in this combination, a determination step "is the communication data rate equal to or less than the second threshold value?" Is provided between step S21 and step S31 in FIG. 10, and the determination result of this determination step is "YES". In the case of, the process proceeds to step S22, and in the case of “NO”, the process proceeds to step S31.

In the above-described embodiment, the wireless communication device can suppress the power consumption, the occurrence of the communication loss, and the power consumption and the occurrence of the communication loss.

Further, in the above-described embodiment, an example in which the wireless communication unit 13 of the wireless sensor 10 performs wireless communication conforming to a communication standard such as LoRa (registered trademark), which is a kind of low power consumption long-distance wireless communication, has been described. However, the wireless communication unit 13 may perform wireless communication using another wireless communication standard using an unlicensed band such as ISA100.11a or WirelessHART (registered trademark).

Further, the data transmission cycle that can be set in the table TB1 used in the first embodiment is not limited to that shown in FIG. 3, and any data transmission cycle can be set. Further, the communication data rate that can be set in the table TB2 used in the second embodiment is not limited to that shown in FIG. 7, and any communication data rate can be set.

10 Wireless sensor 12 Storage unit 13 Wireless communication unit 14 Wireless communication unit 15 Control unit BT Battery CD setting information TB1 table TB2 table TM terminal device

Claims (10)

The first wireless communication unit that performs wireless communication using a frequency band that does not require a wireless station license,
The first operation mode in which the availability of the channel used for data transmission is confirmed in advance and then the data is transmitted to the first wireless communication unit, and the data is sent to the first wireless communication unit without the prior confirmation. A control unit that controls switching between the second operation mode and
A wireless communication device equipped with. The wireless communication device according to claim 1, wherein the control unit controls switching between the first operation mode and the second operation mode according to at least one of a data transmission cycle, a communication data rate, and an error rate. .. In the control unit, the data transmission cycle is equal to or less than a predetermined first threshold value, the communication data rate is equal to or less than a predetermined second threshold value, or the error rate is a predetermined third threshold value. The wireless communication device according to claim 2, wherein when the value is larger than the threshold value, control is performed to set the first operation mode. It is provided with a storage unit that stores setting information used for switching control between the first operation mode and the second operation mode.
The control unit controls switching between the first operation mode and the second operation mode based on the setting information stored in the storage unit.
The wireless communication device according to claim 3. The wireless communication device according to claim 4, further comprising a second wireless communication unit that performs short-range wireless communication with an external device to acquire the setting information. The setting information defines a first data transmission cycle in which the first operation mode can be executed and a second data transmission cycle in which the second operation mode can be executed. The table is included
In the first data transmission cycle, the data transmission cycle below the first threshold value and the data transmission cycle larger than the first threshold value can be set.
Only the data transmission cycle larger than the first threshold value can be set in the second data transmission cycle.
The wireless communication device according to claim 4 or 5. The setting information defines a second communication data rate capable of executing the first operation mode and a second communication data rate capable of executing the second operation mode. Table is included
For the first communication data rate, the communication data rate below the second threshold value and the communication data rate larger than the second threshold value can be set.
Only the communication data rate, which is larger than the second threshold value, can be set as the second communication data rate.
The wireless communication device according to claim 4 or 5. The setting information includes at least one of the first threshold value, the second threshold value, and the third threshold value.
When the data transmission cycle is equal to or less than the first threshold value, the communication data rate is equal to or less than the second threshold value, or the error rate is larger than the third threshold value, the control unit may use the control unit. , The first operation mode is controlled, the data transmission cycle is larger than the first threshold value, the communication data rate is larger than the second threshold value, or the error rate is the said error rate. If it is equal to or less than the third threshold value, control is performed to switch to the second operation mode.
The wireless communication device according to claim 4 or 5. The wireless communication device according to any one of claims 1 to 8, further comprising a battery that supplies electric power to the first wireless communication unit and the control unit. The wireless communication device according to claim 9, wherein the battery is replaceable.

Images