JP7582858B2 - Wireless communication device and wireless communication system - Google Patents

Description

The present invention relates to a wireless communication device and a wireless communication system.

In recent years, with the advancement of connected cars, wireless communication has been performed between user terminals such as smartphones and wireless communication devices installed in vehicles. In this case, a communication method using a high frequency band (quasi-millimeter wave band or millimeter wave band) such as 5G or Wi-Fi (IEEE802.ad) may be used. In communication in the high frequency band, spatial propagation loss increases compared to communication methods using low frequency bands, so technology is used to give the antenna a sharp directivity and improve the antenna gain to improve communication quality. In this case, directivity control technology may be used to control the direction of the antenna's directivity in order to secure communication coverage that would be sacrificed by improving the antenna gain.

For example, the wireless communication device in a vehicle in Patent Document 1 includes a Bluetooth (registered trademark) communication unit 50 with multiple wireless antennas that can switch directivity according to each seat position. When searching for the location of a mobile phone, each directional antenna is switched in turn to attempt communication with the mobile phone, and the mobile phone is identified as being located in the area corresponding to the directional antenna that best detects the signal from the mobile phone. When the signal is best detected in the direction of the driver's seat, the system is automatically set to hands-free calling. Also, when the signal is best detected in the direction of the other seats, the system is automatically set to handset calling.

JP 2005-354312 A

However, in conventional technology, when radio waves emitted from an in-vehicle wireless communication device coexist with radio waves emitted from a base station outside the vehicle, the radio waves emitted from the in-vehicle wireless communication device may act as interference waves and cause communication problems for the user terminal. For example, when the radio waves emitted from the base station have sufficient strength, the radio waves emitted from the in-vehicle wireless communication device are, so to speak, unnecessary radio waves, and the in-vehicle wireless communication device wastes power by emitting radio waves. Furthermore, in conventional directional control technology, radio wave radiation processing is performed even for seats where no passenger is seated, resulting in wasted power consumption.

The present invention has been made in consideration of the problems inherent in the conventional technology. The object of the present invention is to provide a wireless communication device and a wireless communication system that can reduce wasteful power consumption by suppressing the emission of unnecessary radio waves while maintaining communication quality.

In a wireless communication device according to an aspect of the present invention, which is capable of setting multiple directivities for the transmission and reception directions of radio waves, the device includes a user position information acquisition unit that acquires position information of a user using a user terminal that is present inside a mobile body in which the wireless communication device is installed and that is to perform wireless communication with the wireless communication device, a radio wave strength information acquisition unit that acquires radio wave strength information regarding the radio wave strength of radio waves emitted from a base station installed outside the mobile body and that is to be received by the user terminal, a directivity control unit that sets the directivity in the direction of the user's position when the radio wave strength information is equal to or less than a predetermined threshold, and a transmission and reception processing unit for performing wireless communication with the user terminal, and it is preferable that the operation of the directivity control unit and the transmission and reception processing unit for wireless communication with the user terminal is stopped when the radio wave strength information exceeds the predetermined threshold.

The present invention makes it possible to provide a wireless communication device and a wireless communication system that can reduce wasteful power consumption by suppressing the emission of unnecessary radio waves while maintaining communication quality.

1 is a schematic diagram showing an example of implementation of a wireless communication system including a wireless communication device according to an embodiment of the present invention; FIG. 2 is an enlarged schematic diagram of the periphery of the rear left seat in FIG. 1 according to the present embodiment. 1 is a block diagram showing an example of a configuration of a wireless communication device according to an embodiment of the present invention; 4 is a flowchart showing an example of the operation of the wireless communication device according to the present embodiment. FIG. 1 is a diagram showing an example of a main part of an overall configuration according to a comparative example; 11 is a flowchart showing an example of an operation according to a comparative example. FIG. 11 is a schematic diagram illustrating an example of an operation according to a comparative example.

Below, an example of a wireless communication device and a wireless communication system according to the present embodiment will be described in detail with reference to the drawings. Note that the embodiments described below are comprehensive or specific examples. The numerical values, shapes, materials, components, installation positions and connection forms of the components, steps, and order of steps shown in the following embodiments are merely examples and are not intended to limit the present disclosure. Furthermore, among the components in the following embodiments, components that are not described in an independent claim that indicates a top-level concept will be described as optional components. Furthermore, the dimensional ratios in the drawings are exaggerated for the convenience of explanation and may differ from the actual ratios.

(Overview of wireless communication system)
An operation example of a wireless communication system 1000 including a wireless communication device 100 as an in-vehicle wireless communication device according to the present embodiment will be described with reference to Figures 1 to 4. In the following description, the wireless communication device may be referred to as a node.

Figure 1 is a schematic diagram showing an image of a node, which is a wireless communication device 100, installed on the roof of a vehicle as a moving body. The node can perform wireless communication not only with a user terminal 200 inside the moving body, but also with a base station 300 outside the moving body. Furthermore, the user terminal 200 can perform wireless communication with a base station 300 outside the moving body.

As an example, the node and the user terminal 200 inside the mobile body can transmit and receive data such as video information, music information, and call information, and the user terminal 200 can have the functions of a so-called smartphone. These data may be received by the node from a base station 300 outside the mobile body, and then re-emitted from the node to the user terminal 200. The user terminal 200 inside the mobile body can also transmit and receive these data directly to and from a base station 300 outside the mobile body.

When wireless communication device 100, which is an in-vehicle wireless device mounted in a vehicle, communicates wirelessly with user terminal 200, user position information acquired from a user position information acquisition sensor such as a seat belt reminder mounted in the vehicle is used to control the directionality of the antenna of the wireless communication device. With this configuration, radio wave radiation processing is not performed for seats where no passenger is seated, making it possible to reduce waste of power consumption.

Furthermore, a radio wave intensity acquisition unit capable of measuring the intensity of radio waves used for wireless data communication is attached to the seat belt webbing or the like, and the radio wave intensity from the base station 300 outside the mobile body is measured and compared with a predetermined radio wave intensity. Note that in this specification, the webbing may be referred to as a belt. If the radio wave intensity from the base station 300 outside the mobile body is stronger than a predetermined threshold radio wave intensity, the wireless communication device 100 does not perform wireless communication with the user terminal 200. In other words, if the radio waves emitted from the base station 300 have sufficient intensity, the radio waves emitted from the wireless communication device 100 are, so to speak, unnecessary radio waves, and therefore, the wireless communication device 100 can stop emitting radio waves to reduce power waste.

In addition, when the radio wave strength from the base station 300 outside the mobile body is less than a predetermined threshold value, the wireless communication device 100 performs directivity control according to the user position, starts or continues wireless communication with the user terminal 200, and maintains communication quality.

Furthermore, when new user location information is acquired from the user location information acquisition unit, the wireless communication device 100 executes directivity control according to the user location, starts or continues wireless communication with the user terminal 200, and maintains communication quality. Even when new user location information is not acquired from the user location information acquisition unit, the radio wave strength acquisition unit executes measurement of radio wave strength at a predetermined time interval or at a predetermined timing. In this case, when the radio wave strength from the base station 300 is greater than a predetermined threshold radio wave strength, the wireless communication device 100 may switch to wireless communication between the base station 300 and the user terminal 200 instead of the wireless communication device 100. Since the wireless communication switching technology is a known technology, a detailed description is omitted in this specification. Then, when the radio wave strength from the base station 300 is less than a predetermined threshold radio wave strength, the wireless communication device 100 executes wireless communication with the user terminal 200.

When the radio wave intensity acquisition unit measures the radio wave intensity, it may temporarily suspend the function of the wireless communication device or put it into a sleep state to stop the radio waves emitted from the wireless communication device, making it easier to identify the radio waves emitted from the base station 300 outside the vehicle. It is not necessary to identify the base station 300 outside the vehicle, but this does not limit the identification of the base station 300 outside the vehicle.

(Description of the state in which the user is seated in the rear left seat)
FIG. 2 is a schematic diagram showing an enlarged view of the area around the rear left seat in FIG. 1, with a user 20 seated in the rear left seat at the center.

A user 20 sitting in the rear left seat is fastening a seat belt 30 and operating a user terminal 200. The user terminal 200 is capable of performing wireless communication with a base station 300 (not shown in FIG. 2) or a wireless communication device 100 mounted on a mobile object.

The user position information acquisition unit 160 can be formed integrally with the seat belt reminder. As described later, the user position information acquisition unit 160 can also be formed separately from the seat belt reminder. As an example, the user position information acquisition unit 160 can be realized by a seating sensor system included in the seat belt reminder. For example, the seating sensor system detects the application of a load to the seat using a sensor, and when the seat belt 30 is fastened to the buckle, outputs information indicating that the user is seated in the seat equipped with the seat belt 30 as user position information. The information may or may not include seat identification information. The information may also be configured to include coordinate information of the user on the moving object.

The wireless communication device 100, which has acquired the user position information, controls the initial radio wave beam direction B1 of the wireless communication device 100 to a radio wave beam direction B2 directed toward the rear left seat where the user 20 is seated. In this way, the wireless communication device 100 controls the directivity of the radio wave beam, thereby enabling the wireless communication device 100 to maintain good communication quality of the wireless communication with the user terminal 200. However, in this case, when the base station 300 is performing wireless communication with the user terminal 200, the radio waves from the wireless communication device 100 may become interference waves, so the wireless communication device 100 needs to stop emitting radio waves to the user terminal 200.

The wireless communication device 100 operates the radio wave intensity information acquisition unit 170, which measures the radio wave intensity from the base station 300 at a position close to the user terminal 200, to acquire radio wave intensity information. In this case, the wireless communication device 100 stops emitting radio waves so that the radio wave intensity information acquisition unit 170 does not measure the radio waves emitted from the wireless communication device 100. The wireless communication device 100 compares the value of the radio wave intensity indicated by the acquired radio wave intensity information with a predetermined threshold value that can maintain good quality of wireless communication between the user terminal 200 and the base station 300. If the value of the radio wave intensity is greater than the predetermined threshold value, the wireless communication device 100 does not execute wireless communication with the user terminal 200. In other words, the wireless communication device 100 does not start wireless communication with the user terminal 200 or interrupts it. If the value of the radio wave intensity is greater than the predetermined threshold value, the wireless communication device 100 controls the directivity of the radio wave beam from the user position information, and starts, resumes, or continues wireless communication with the user terminal 200.

The radio wave intensity information acquisition unit 170, which measures radio wave intensity as described in detail below, is formed integrally with the seat belt 30. For example, the radio wave intensity information acquisition unit 170 is embedded in the seat belt 30. An antenna using copper foil and fluororesin as antenna materials can have a small and flexible structure. The electronic circuit that performs the measurement and transmission operations can also be realized with an integrated circuit such as a microchip. Such a flexible radio wave intensity information acquisition unit 170 can also be wound up integrally with the webbing. In this embodiment, the radio wave intensity information acquisition unit 170 is configured to measure the radio wave intensity from the base station 300.

The radio wave intensity information acquisition unit 170 can be included in the seat belt reminder. For example, as described above, the radio wave intensity information acquisition unit 170 can be included in the webbing. In this case, the radio wave intensity information acquisition unit 170 may be battery-powered or may be configured to be powered by the seat belt reminder system. The radio wave intensity information acquisition unit 170 can also be included in the webbing so as to be located on the chest of the user wearing the seat belt. The radio wave intensity information acquisition unit 170 can be attached to the webbing or the like so as to be located at least between the body surface facing the user terminal 200 in front of the user wearing the seat belt and the user terminal 200, or can be arranged so as to be included. The radio wave intensity information acquisition unit 170 can also be arranged so as to be included in multiple pieces in the seat belt. When multiple radio wave intensity information acquisition units 170 are included, the radio wave intensity information control unit 133 can calculate processing information such as the maximum value, average value, and minimum value of the multiple received radio wave intensity information by arithmetic processing, and use any one or a combination of the calculated processing information. For example, if the radio wave strength information includes the position information of the radio wave strength information acquisition unit 170, the radio wave strength information control unit 133 can supplement and estimate the radio wave strength around the user, and estimate the radio wave strength received by the user terminal 200. The position of the user terminal 200 may be a position that is determined in advance in correspondence with the seating position, or the wireless communication device 100 can be configured to estimate the position from the radio waves received from the user terminal 200.

In addition, the receivable frequency range of the measurement unit of the radio wave intensity information acquisition unit 170 may cover the receivable frequency range of the user terminal 200, and may include a frequency correction unit so that the gain is flat within the receivable frequency range.

(Configuration of wireless communication device)
An example of the configuration of a wireless communication device 100 having the functions outlined above will be described with reference to FIG.

The wireless communication device 100 includes a transmission/reception processing unit 110, a directivity control unit 120, a control unit 130, a storage unit 140, an I/F unit 150, a user position information acquisition unit 160, and a radio wave intensity information acquisition unit 170 (I/F: Interface). An antenna unit ANT constituting a directional antenna and an electronic device 180 are options that may or may not be included in the wireless communication device 100. The user position information acquisition unit 160 and the radio wave intensity information acquisition unit 170 can transmit and receive various information to and from the I/F unit 150 via wired or wireless communication.

The wireless communication device 100 may be a general computer including the above blocks. The general computer executes a control program to realize the functions shown in FIG. 3. Only the parts related to the features of this embodiment will be described below. Therefore, the wireless communication device 100 may of course include other functional blocks that are not directly related to the features of this embodiment. In addition, the wireless communication device 100 may be placed in a position that provides a good communication environment with the user terminal 200 located inside the mobile object, for example, where line of sight can be easily ensured. Examples of positions that provide a good communication environment with the user terminal 200 include the ceiling of a mobile object, or the roof of a vehicle, but are not limited to these.

The storage unit 140 may be a read only memory (ROM), a random access memory (RAM), a hard disk, etc. The storage unit 140 may also store various data such as input data, output data, and intermediate data for the wireless communication device 100 to execute processing. Some functions of the wireless communication device 100 may be executed by a central processing unit (CPU).

The antenna unit ANT is an antenna capable of forming multiple directivities, and may be an array antenna capable of setting a radio wave beam in any direction using multiple antenna elements. It may also be a collection of multiple antennas with directivity. In an array antenna, by adjusting the current phase of each antenna so that radio waves from multiple antenna elements are added in phase, it is possible to direct the directivity of the radio wave beam in any direction while the antenna elements are fixed. Note that the above description of the antenna unit ANT has been about the part that performs wireless communication with the user terminal 200, but the antenna unit ANT may also include an antenna for wireless communication with the base station 300. The antenna for wireless communication with the base station 300 may be provided outside the mobile body as an antenna alone, or may be provided outside the mobile body together with an antenna cover. It may also be configured to be attached to a part with small propagation loss, such as a window part of the mobile body.

The transmission/reception processing unit 110 performs processes such as modulation processing for transmitting information via radio waves from the antenna unit ANT, or demodulation processing of radio waves received by the antenna unit ANT, and performs processes such as generating and analyzing PHY frames. Parameters for performing processes such as modulation and demodulation can be stored in the transmission/reception processing information storage unit 141 of the storage unit 140. The transmission/reception processing unit 110 can perform functions that correspond to the physical layer of a hierarchy in a model in which communication protocols (communication rules) are hierarchically organized.

The directivity control unit 120 generates a directivity control signal for controlling the directivity of the antenna in accordance with the type of antenna of the antenna unit ANT. For example, when the antenna unit ANT is an array antenna, the directivity control unit 120 generates a directivity control phase signal for setting the phase of the transmitted radio wave or the received radio wave for each antenna element. In addition, as necessary, the directivity control unit 120 generates a directivity control amplitude signal for setting the amplitude of the transmitted radio wave or the received radio wave for each antenna element of the array antenna. These directivity control phase signals and the directivity control amplitude signals generated as necessary can be generated by the directivity control unit 120 in accordance with the direction information of the radio wave beam transmitted from the user position information control unit 132. In addition, when there are multiple users in the mobile body and the direction information of multiple radio wave beams is transmitted, the directivity control unit 120 can generate multiple directivity control signals simultaneously or in the order of transmission. Therefore, the wireless communication device 100 can communicate with multiple user terminals 200 simultaneously or sequentially. The control of communicating with the user terminals 200 simultaneously or sequentially can be executed by the transmission/reception control unit 131.

In addition, if the antenna unit ANT includes multiple antennas with mutually different directivities, the directivity control unit 120 generates a directivity control selection signal that indicates which of the antennas to use. Note that other directivity control methods that do not use a phase shifter will be described in detail in the modified examples.

In addition, since the wireless communication device 100 performs wireless communication with the user terminal 200, it is also possible to fine-tune the radio wave beam in the direction generated by the initially generated directional control signal to generate a radio wave beam in the direction that provides the best wireless communication with the user terminal 200.

The control unit 130 includes a transmission/reception control unit 131, a user position information control unit 132, a radio wave intensity information control unit 133, and an operation control unit 134.

The transmission/reception control unit 131 executes processes such as multiple access control for sharing radio waves, which serve as a transmission medium, between the wireless communication device 100 and multiple user terminals 200. Parameters for executing processes such as multiple access control can be stored in the transmission/reception processing information storage unit 141 of the storage unit 140. The transmission/reception control unit 131 can execute functions that correspond to the MAC layer of a hierarchy in a model in which communication protocols are hierarchical.

The user position information control unit 132 stores the user position information acquired by the user position information acquisition unit 160 in the user position information storage unit 142, and performs an operation of controlling the directivity control unit 120 based on the user position information. For example, when the user position information acquisition unit 160 detects that the user has sat in a seat in the moving body, the user position information acquisition unit 160 transmits the position information of the seat where the user is seated to the user position information control unit 132 by wire or wirelessly. The user position information control unit 132, which has received the position information of the seat where the user is seated, stores the position information in the user position information storage unit 142 as user position information. The position information may be information indicating a position specified by dividing the inside of the moving body by any known coordinate system. In this case, the position information of the wireless communication device 100 indicated in the coordinate system may also be stored in the storage unit 140. Therefore, the user position information control unit 132 can determine the direction of the radio wave beam emitted from the wireless communication device 100 based on the position information of the wireless communication device 100 and the user position information, and transmit the determined direction information of the radio wave beam to the directivity control unit 120.

When the user position information transmitted from the user position information acquisition unit 160 differs from the user position information stored in the user position information storage unit 142, the user position information control unit 132 stores the latest user position information in the user position information storage unit 142. Then, the user position information control unit 132 can transmit the latest direction information of the radio wave beam to the directivity control unit 120.

In addition, when multiple users are seated in the vehicle, the user position information of each of the multiple users is transmitted to the user position information control unit 132 and stored in the user position information storage unit 142.

The position information may also be associated with information indicating a specific position or area within the vehicle. For example, if information indicating the driver's seat is indicated by "zaseki1", when the user sits in the driver's seat, the user position information may be stored as "zaseki1" in the user position information storage unit 142. In this case, the direction information of the radio beam may be stored in the user position information storage unit 142 in association with "zaseki1", which is the seat identification information. In this case, as an example, when the seat identification information is transmitted from the user position information control unit 132 to the directivity control unit 120, the directivity control unit 120 can extract the corresponding direction information of the radio beam from the user position information storage unit 142.

The radio wave intensity information control unit 133 compares the radio wave intensity information acquired by the radio wave intensity information acquisition unit 170 with the threshold value of information corresponding to the predetermined radio wave intensity information stored in the radio wave intensity related information storage unit 143. Also, before the radio wave intensity information control unit 133 acquires radio wave intensity information from the radio wave intensity information acquisition unit 170, the operation control unit 134 controls the transmission/reception processing unit 110 and the directivity control unit 120 so as not to radiate radio waves from the antenna unit ANT. To this end, before the radio wave intensity information control unit 133 acquires radio wave intensity information from the radio wave intensity information acquisition unit 170, the radio wave intensity information control unit 133 transmits a radio wave intensity information acquisition start signal to the operation control unit 134. The operation control unit 134 that has received the acquisition start signal controls the transmission/reception processing unit 110 and the directivity control unit 120 so as not to radiate radio waves from the antenna unit ANT. Also, after the radio wave intensity information control unit 133 acquires radio wave intensity information from the radio wave intensity information acquisition unit 170, the radio wave intensity information control unit 133 transmits a radio wave intensity information acquisition end signal to the operation control unit 134. The operation control unit 134, which has received the acquisition end signal, controls the transmission/reception processing unit 110 and the directivity control unit 120 to emit or receive radio waves from the antenna unit ANT. In this way, by configuring the wireless communication device 100 not to emit unnecessary radio waves while the radio wave intensity information acquisition unit 170 is operating, it is possible to configure the radio wave intensity information acquisition unit 170 not to acquire radio wave intensity information from the wireless communication device 100.

When the radio wave intensity information acquired by the radio wave intensity information control unit 133 is greater than a predetermined threshold, the radio wave intensity information control unit 133 estimates that radio waves with good communication quality are being transmitted to the user terminal 200 from a base station 300 outside the mobile body. When the radio wave intensity information control unit 133 estimates that radio waves with good communication quality are being transmitted from the base station 300 to the user terminal 200, the wireless communication device 100 interrupts wireless communication with the user terminal 200.

In addition, when the radio wave intensity information acquired by the radio wave intensity information control unit 133 is equal to or lower than a predetermined threshold, the radio wave intensity information control unit 133 estimates that radio waves having good communication quality are not being transmitted from the base station 300 outside the mobile body to the user terminal 200. When the radio wave intensity information control unit 133 estimates that radio waves not having good communication quality are not being transmitted from the base station 300 to the user terminal 200, the wireless communication device 100 starts or resumes wireless communication with the user terminal 200. For example, when the user terminal 200 is transmitting and receiving the same content or call with the wireless communication device 100 or the base station 300, it becomes possible to select the wireless communication device 100 or the base station 300 that can maintain better communication quality.

The storage unit 140 includes a transmission/reception processing information storage unit 141, a user position information storage unit 142, and a radio wave intensity related information storage unit 143.

The transmission/reception processing information storage unit 141 stores information such as control parameter values required for wireless communication, identification information of the wireless communication device 100, location information of the wireless communication device 100, and route information for wireless communication. The transmission/reception processing unit 110 and the transmission/reception control unit 131 can refer to the transmission/reception processing information storage unit 141 to execute processing such as modulation/demodulation processing, communication frame formation processing, and multiplex communication processing.

The user position information storage unit 142 stores the user position information acquired by the user position information acquisition unit 160. As described above, the user position information may be coordinate information of the mobile body in which the user is riding, or may be information such as identification information of the seat of the mobile body in which the user is riding. In addition, if the user position information is not coordinate information of the mobile body in which the user is riding, the user position information may be stored in association with directional information of the radio wave beam. In addition, the user position information storage unit 142 may store coordinate information of the wireless communication device 100 or the antenna unit ANT of the wireless communication device 100.

The radio wave strength related information storage unit 143 stores the radio wave strength information acquired by the radio wave strength information acquisition unit 170 and a predetermined threshold or threshold information for the radio wave strength information. The acquired radio wave strength information may be information obtained by converting the strength of the received radio wave into information such as RSSI (Received Signal Strength Indicator). When the radio wave strength information is expressed as communication quality information, information such as BER (bit error rate) and PER (Packet Error Rate) may be included. Furthermore, the communication quality information may include information such as SNR (Signal to Noise Ration) and RCPI (Received Channel Power Indicator). Furthermore, the communication quality information may include communication delay time information and shielding loss information. The communication quality information may be any one of the above various communication quality information. However, by making the radio wave strength information the strength of the received radio wave, it is possible to realize a simple, small, and low-cost configuration of the radio wave strength information acquisition unit 170. The predetermined threshold or threshold information is a numerical value or information indicating a numerical value that indicates a level at which the radio quality from the base station 300 is good in the radio wave intensity information acquisition unit 170.

The I/F unit 150 is an input/output interface for communication data and various data to be transmitted and received, and may be an interface with devices such as sensors connected to the wireless communication device 100, or with electronic devices. An ECU (Electronic Control Unit) may be configured by the devices or electronic devices connected to the I/F unit 150. The electronic devices may include electronic devices such as vehicle control devices, vehicle sensing devices, vehicle surrounding information acquisition devices, and entertainment devices as in-vehicle devices. The vehicle control devices may include navigation devices and autonomous driving control devices.

The user position information acquisition unit 160 can be realized by any sensor capable of acquiring user position information. As an example, the user position information acquisition unit 160 can be realized by a seating sensor system included in a seat belt reminder or the like. For example, the seating sensor system detects that a load is applied to the seat with a sensor, and when the webbing is fastened to the buckle, outputs information indicating that the user is seated in the seat equipped with the seat belt. If the information includes seat identification information, the information can be stored as user position information in the user position information storage unit 142. If the information does not include seat identification information, the information can include seat identification information and be stored as user position information in the user position information storage unit 142. If the information is expressed as coordinate information, the coordinate information can be stored as user position information in the user position information storage unit 142. Other forms of the user position information acquisition unit 160 will be described in detail in a modified example.

The radio wave intensity information acquisition unit 170 can be realized by an antenna (not shown) that receives radio waves and a measurement unit (not shown) that measures the intensity of the received radio waves. The antenna is preferably an antenna whose receivable range is the same as that of the antenna unit ANT of the wireless communication device 100 or includes the receivable range of the antenna unit ANT. Therefore, it may be an antenna with any structure and directivity that has the receivable range. Note that when the radio wave intensity information acquisition unit 170 is installed adjacent to a seat of a moving object, it is also possible that the lower hemisphere of the seat and the rear of the seat are not included in the receivable range.

The radio wave intensity information acquisition unit 170 can be included in the seat belt reminder. For example, the radio wave intensity information acquisition unit 170 can be included in the seat belt. In this case, the radio wave intensity information acquisition unit 170 may be battery-powered or may be configured to be powered by the seat belt reminder system. The radio wave intensity information acquisition unit 170 can also be included in the webbing so as to be located on the chest of the user wearing the webbing. The radio wave intensity information acquisition unit 170 can be attached to the webbing so as to be located at least between the body surface facing the user terminal 200 in front of the user wearing the webbing and the user terminal 200, or can be arranged so as to be included in the webbing. The radio wave intensity information acquisition unit 170 can also be arranged so as to be included in the seat belt in multiple units. When multiple radio wave intensity information acquisition units 170 are included, the radio wave intensity information control unit 133 can calculate processing information such as the maximum value, average value, and minimum value of the multiple received radio wave intensity information by arithmetic processing, and use any one or a combination of the calculated processing information. For example, if the radio wave strength information includes the position information of the radio wave strength information acquisition unit 170, the radio wave strength information control unit 133 can supplement and estimate the radio wave strength around the user, and estimate the radio wave strength received by the user terminal 200. The position of the user terminal 200 may be a position that is determined in advance in correspondence with the seating position, or the wireless communication device 100 can be configured to estimate the position from the radio waves received from the user terminal 200.

The receivable frequency range of the measurement unit of the radio wave strength information acquisition unit 170 may cover the receivable frequency range of the user terminal 200, and may include a frequency correction unit so that the gain is flat in the receivable frequency range. As described above, the measurement unit may convert the strength of the received radio wave into information such as RSSI. Furthermore, when the radio wave strength information is expressed as communication quality information, the configuration may be such that information such as BER and PER is measured. Furthermore, the communication quality information to be measured may include SNR, RCPI, communication delay time information, and shielding loss information. In order to measure this information, the radio wave strength information acquisition unit 170 may be configured to be able to access the transmission/reception processing information storage unit 141.

With the above configuration, it is possible to suppress the emission of unnecessary radio waves from the wireless communication device 100 while maintaining the communication quality of the user terminal, thereby suppressing waste of power consumption by the wireless communication device 100.

(Example of operation of wireless communication device when crew members are on board)
FIG. 4 is a flowchart showing an example of the operation of the wireless communication device when a passenger is on board.

In step S401, the user position information acquisition unit 160 of the wireless communication device 100 acquires user position information and transmits the acquired user position information to the user position information control unit 132. Next, the wireless communication device 100 proceeds to step S402.

In step S402, the operation control unit 134 of the wireless communication device 100 receives a signal to start acquiring radio wave intensity information from the radio wave intensity information control unit 133. Having received the acquisition start signal, the operation control unit 134 controls the transmission/reception processing unit 110 and the directivity control unit 120 so as not to radiate radio waves from the antenna unit ANT. Next, the wireless communication device 100 proceeds to step S403.

In step S403, the radio wave strength information acquisition unit 170 of the wireless communication device 100 receives a radio wave strength information acquisition start signal from the radio wave strength information control unit 133, measures the radio wave strength, generates radio wave strength information, and transmits the generated radio wave strength information to the radio wave strength information control unit 133. Next, the wireless communication device 100 proceeds to step S404.

In step S404, the radio wave intensity information control unit 133 compares the value of the radio wave intensity indicated by the received radio wave intensity information with a predetermined threshold value stored in the radio wave intensity related information storage unit 143. If the value of the radio wave intensity indicated by the radio wave intensity information is equal to or greater than the predetermined threshold value (step S404: YES), the wireless communication device 100 proceeds to step S402. That is, since it is estimated that the user terminal 200 is receiving radio waves from the base station 300 that can maintain good communication quality, the wireless communication device 100 stops wireless communication with the user terminal 200. If the value of the radio wave intensity indicated by the radio wave intensity information is smaller than the predetermined threshold value (step S404: NO), the wireless communication device 100 proceeds to step S405. That is, it is estimated that the user terminal 200 is not receiving radio waves from the base station 300 that can maintain good communication quality, so the wireless communication device 100 starts or resumes wireless communication with the user terminal 200.

In step S405, the operation control unit 134 controls the transmission/reception processing unit 110 and the directivity control unit 120 to start operating. Next, the wireless communication device 100 proceeds to step S406.

In step S406, the directivity control unit 120 generates directivity control information that matches the type of antenna of the antenna unit ANT from the direction information of the radio wave beam generated by the user position information control unit 132, and outputs the generated directivity control information. Next, the wireless communication device 100 proceeds to step S407.

In step S407, the user position information acquisition unit 160 of the wireless communication device 100 acquires user position information and transmits the acquired user position information to the user position information control unit 132. Next, the wireless communication device 100 proceeds to step S408.

In step S408, the user position information control unit 132 compares the user position information acquired in step S401 with the user position information acquired in step S407, and determines whether or not there has been a change in the user position. If there has been a change in the user position (step S408: YES), the wireless communication device 100 proceeds to step S402. If there has been no change in the user position (step S408: NO), the wireless communication device 100 proceeds to step S409.

In step S409, the wireless communication device 100 executes wireless communication processing with the user terminal 200. The wireless communication processing may be executed for each minimum unit such as a segment, packet, or frame, or may be executed for each of a plurality of minimum units. Next, the wireless communication device 100 returns to step S401.

With the above configuration, it is possible to suppress the emission of unnecessary radio waves from the wireless communication device 100 while maintaining the communication quality of the user terminal, thereby suppressing waste of power consumption by the wireless communication device 100.

(Variation 1)
In the above embodiment, the mobile object is mainly an automobile. The network constructed by the wireless communication system 1000 installed in the mobile object is described as an example. However, the mobile object in the embodiment is not limited to an automobile, and can be applied to any network constructed inside a mobile object such as a train, an airplane, or a ship, or inside a structure such as a house or a factory.

(Variation 2)
In the above embodiment, the directivity control unit 120 has been described as controlling the directivity by controlling the phase input to the antenna elements. However, it is also possible to employ an adaptive array antenna in which the directivity is controlled by the directivity control unit 120 controlling the phase and amplitude input to the antenna elements, for the antenna unit ANT.

(Variation 3)
In the above embodiment, the directivity control unit 120 mainly controls the directivity using a phase shifter. However, it is also possible to provide a switch circuit such as a Rotman lens or a Butler matrix in the directivity control unit 120 to generate a directivity control signal.

(Variation 4)
In the above embodiment, the information regarding the riding status of the user of the mobile body has been described mainly using a seat belt reminder system (not shown), but it is also possible to adopt an occupant detection sensor of an airbag system as the user position information acquisition unit 160. It is also possible to configure the user position information acquisition unit 160 to include an imaging device and estimate the presence or absence of a user in the mobile body and the user's position from the imaging information. In addition, when the radio wave intensity information acquisition unit 170 is provided in the seat belt, the radio wave intensity information acquisition unit 170 is not limited to being located near the user's chest, and may be provided at any position facing the surface of the user's body.

(Variation 5)
In the above embodiment, the wireless communication device 100 may be installed in the periphery of the vehicle, such as the body of the vehicle, but the installation position of the wireless communication device 100 is not limited to these positions. For example, the wireless communication device 100 may be installed under the floor, ceiling, window glass, etc. of the vehicle, which has a radio wave environment that is less affected by the user position of the vehicle. In addition, the underfloor and the ceiling may be components inside the vehicle that make up the body.

(Variation 6)
It is also possible to configure the directivity control unit 120 to include a radio wave arrival direction estimation unit (not shown) so that, instead of controlling the directivity based on user position information, the directivity is controlled in the estimated radio wave arrival direction and wireless communication is performed between the user terminal 200 and the wireless communication device 100. By configuring in this way, it may be possible to control the directivity more accurately and maintain good communication quality.

(Variation 7)
In the above embodiment, it was assumed that the wireless communication device 100 and the user terminal 200 maintain good communication quality by wireless communication in a clear environment. However, there may be cases where the wireless communication can maintain good communication quality by other radio wave environments. For example, it is possible to install a radio wave reflector that easily reflects radio waves from the wireless communication device 100 in the direction of the user's seat on at least a part of the side of the moving object, thereby maintaining good communication quality between the wireless communication device 100 and the user terminal 200. That is, for example, it is also possible to maintain good communication quality by matching the radio wave incidence angle from the wireless communication device 100 to the radio wave reflector and the radio wave emission angle from the radio wave reflector to the user terminal 200 within an error of a few percent. In this case, the surface of the radio wave reflector may be flat or may have a structure with a slope.

(Variation 8)
In the above description of the embodiment, no specific data is described as the communication data between the base station 300 and the wireless communication device 100, but the application is not limited. For example, the communication data may be video data, audio data, application data such as games, news information, etc., wirelessly communicated between the base station 300 and the user terminal 200. In this case, the wireless communication device 100 can also operate as a relay terminal. In addition, the communication data between the base station 300 and the user terminal 200 may be different from the communication data between the wireless communication device 100 and the user terminal 200.

Comparative Example
A comparative example, which is a hands-free telephone system including a hands-free device 400 connected to a directional antenna with fixed directivity, will be described with reference to FIGS. 5 to 7. FIG.

As shown in FIG. 5, directional antenna 61 has a fixed directivity directed toward driver's seat 51, directional antenna 62 has a fixed directivity directed toward rear right seat 52, and directional antenna 63 has a fixed directivity directed toward rear left seat 53. Directional antenna 64 has a fixed directivity directed toward passenger seat 54. By arranging wireless antennas including directional antennas 61, 62, 63, and 64 in the center of the vehicle, a wireless area can be secured for the entire vehicle, making it possible to check whether or not a mobile phone is present inside the vehicle. Also, by comparing the signal strength received by each directional antenna, it is possible to identify which seat the mobile phone is in.

The operation of the hands-free calling system in the comparative example is explained below using the flowchart in Figure 6.

First, in step S610, the location of the mobile phone is searched for. The search method is to identify the location by attempting to communicate with the mobile phone using each directional antenna. Then, if a mobile phone is not detected in step S620, it is determined that a mobile phone that should be set to hands-free calling has not been brought into the vehicle. On the other hand, if a mobile phone is detected, the process proceeds to step S630.

In step S630, a Bluetooth (registered trademark) connection is established between the mobile phone and the hands-free device 400. Thereafter, the hands-free device 400 uses a directional antenna corresponding to the position of the mobile phone to communicate one-to-one with the mobile phone. When multiple mobile phones with Bluetooth (registered trademark) communication functions are brought into the vehicle, one mobile phone is selected from among them and connected. The selection method may, for example, be to notify the user via a speaker or the like that multiple mobile phones have been detected, and to instruct the user to turn off the power of the mobile phone that is not to be selected. This allows the hands-free device 400 to recognize that the user has selected a mobile phone that is continuously powered on.

In step S640, it is determined whether the mobile phone connected via Bluetooth (registered trademark) in step S630 is in the driver's seat. This is determined by comparing the strength of the signals received by the directional antennas 61, 62, 63, and 64. If it is determined that the mobile phone is not in the driver's seat, the process proceeds to step S660, and either normal handset calls or hands-free calls can be used. The following methods can be used to select whether to make a call using the handset or hands-free. For example, when making a call using the mobile phone, the handset can be used as usual. When there is a call on the mobile phone, a display unit and a hands-free start switch are provided in the hands-free device 400, and the incoming call to the mobile phone is notified on the display unit. When the user presses the hands-free start switch, a hands-free call is made, and when the user presses a call start switch or the like provided on the mobile phone, a call is made using the handset.

As a result, for example, even if a passenger other than the driver brings a mobile phone, that passenger can use the mobile phone as usual. Also, even if a mobile phone is detected in a place other than the driver's seat, the passenger can still make a call hands-free. For example, even if there are no other passengers and the driver drives with the mobile phone in the passenger seat, the driver can still make a call hands-free. On the other hand, if it is determined in step S640 that the mobile phone is in the driver's seat, the process proceeds to step S650.

In step S650, it is determined whether the vehicle is moving. The determination method may be to determine that the vehicle is moving by starting the engine, or to actually detect the vehicle speed sensor and make the determination. If it is determined that the vehicle is not moving, the process proceeds to step S660, and either normal handset calls or hands-free calls can be used. As a method for selecting which mode to use for calls, the user may select which mode to use for each incoming call to the mobile phone, as described above. This allows normal handset calls to be made when the vehicle is not moving, even if the mobile phone is brought into the driver's seat. In addition, even if the vehicle is not moving, it is possible to make a call in hands-free mode. For example, if a call is made while the vehicle is temporarily stopped at a traffic light at an intersection, the driver can make a call in hands-free mode. On the other hand, if it is determined in step S650 that the vehicle is moving, the process proceeds to step S670, and a control unit (not shown) restricts the mobile phone to only hands-free calls.

In step S680, it is determined whether or not to search again for the location of the mobile phone. The timing of the re-search may be set to automatically search periodically by setting a timer. If the re-search is not to be performed, the process returns to step S640, where it is determined whether or not the mobile phone is in the driver's seat. In this step S640, the mobile phone is not re-searched, so the previously searched location information of the mobile phone is maintained. In other words, if it was previously determined that the mobile phone was in the driver's seat, it is also determined in step S640 that the mobile phone is in the driver's seat. Conversely, if it was previously determined that the mobile phone was not in the driver's seat, it is also determined in step S640 that the mobile phone is not in the driver's seat. As a result, once the mobile phone is brought to a place other than the driver's seat and set to be usable for both handset calls and hands-free calls, this state is maintained until the mobile phone is re-searched. On the other hand, even if the mobile phone is brought to the driver's seat and set to hands-free calls because the vehicle is running, when the vehicle is stopped after that, the handset can be used for calls by the process of step S660.

If, in step S680, it is necessary to search again for the location of the mobile phone, the process returns to step S610. For example, a timer is set to periodically search again. In this case, even if the mobile phone is first brought into the driver's seat and set to hands-free calling (step S670), when another passenger moves the mobile phone to use it, handset calling is automatically enabled (step S660). Also, when multiple mobile phones equipped with Bluetooth (registered trademark) communication functions are brought into the vehicle, even if one mobile phone is set to hands-free calling, another mobile phone can be re-set to hands-free calling by re-searching for the mobile phones in step S680.

Figure 5 is a schematic diagram showing a situation in which the position of a mobile phone is detected using a wireless antenna having multiple directional antennas 61, 62, 63, and 64 to detect the position of the mobile phone. Directional antenna 61 with a fixed directivity in the direction of the driver's seat 51 is selected, and then directional antenna 62 with a fixed directivity in the direction of the rear right seat 52 is selected. Next, directional antenna 63 with a fixed directivity in the direction of the rear left seat 53 is selected, and directional antenna 64 with a fixed directivity in the direction of the passenger seat 54 is selected. It can be seen from Figure 7 that when there is a mobile phone in the direction of each seat, the radio wave reception strength increases.

However, in the above comparative example, seats with no users are also searched for, which results in unnecessary processing being performed, increasing processing time and the likelihood of increased power consumption.

The following describes the features of the wireless communication device 100 and wireless communication system 1000 of this embodiment.

The wireless communication device 100 according to the first aspect of the present disclosure, which is capable of setting multiple directivities of the transmission and reception directions of radio waves, preferably includes a user position information acquisition unit 160 that acquires position information of a user using the user terminal 200. The user terminal 200 preferably executes wireless communication with the wireless communication device 100 and is present inside the mobile body 10 in which the wireless communication device 100 is installed. In addition, the wireless communication device 100 preferably includes a radio wave intensity information acquisition unit 170 that acquires radio wave intensity information regarding the radio wave intensity of radio waves radiated from a base station 300 installed outside the mobile body 10 that should be received by the user terminal 200. Furthermore, the wireless communication device 100 preferably includes a directivity control unit 120 that sets the directivity in the user's position direction when the radio wave intensity information is equal to or less than a predetermined threshold, and a transmission and reception processing unit 110 for performing wireless communication with the user terminal 200. In addition, it is preferable to stop the operation of the directivity control unit 120 and the transmission and reception processing unit 110 for wireless communication with the user terminal 200 when the radio wave intensity information exceeds the predetermined threshold.

The above configuration makes it possible to reduce wasteful power consumption by suppressing the emission of unnecessary radio waves while maintaining communication quality.

The radio wave intensity information acquisition unit 170 of the wireless communication device 100 according to the second aspect of the present disclosure preferably acquires radio wave intensity information related to the radio wave intensity of radio waves emitted from a base station installed outside the mobile body. In this case, the wireless communication device 100 preferably includes an operation control unit 134 that stops wireless communication between the wireless communication device 100 and all user terminals 200 present inside the mobile body 10 in which the wireless communication device is installed.

With the above configuration, the radio wave intensity information acquisition unit 170 does not measure the radio wave intensity due to unnecessary radio waves from the wireless communication device 100, so it becomes possible to properly measure the radio waves from the base station 300.

The radio wave intensity information acquisition unit 170 of the wireless communication device 100 according to the third aspect of the present disclosure preferably compares the maximum value of the reception intensity of the radio wave received in the frequency band used by the user terminal 200 with a predetermined threshold value. In this case, the radio wave intensity information preferably indicates the reception intensity of the radio wave received by the radio wave intensity information acquisition unit 170.

With the above configuration, the radio wave intensity information acquisition unit 170 has a frequency band equivalent to the frequency band used by the user terminal 200, making it possible to properly measure radio waves from the base station 300.

The user position information acquisition unit 160 of the wireless communication device 100 according to the fourth aspect of the present disclosure is preferably a seating determination device that indicates whether or not the user is seated in a seat including a seat belt 30 provided in a moving object, or an imaging device provided in the moving object.

According to the above configuration, the user position information acquisition unit 160 can be realized easily and at low cost using an existing seating determination device. In addition, the user position information acquisition unit 160 can grasp user position information more accurately in real time using an existing or new imaging device.

The radio wave intensity information acquisition unit 170 of the wireless communication device 100 according to the fifth aspect of the present disclosure preferably acquires radio wave intensity information when the seating determination device determines that the user is seated, or when the imaging device determines that the user is present inside the moving object. In addition, the radio wave intensity information acquisition unit 170 preferably updates the radio wave intensity information when there is a change in the user's position information or for each assigned wireless communication processing period.

According to the above configuration, by specifying the timing for acquiring radio wave intensity information, it becomes possible to appropriately acquire or update radio wave intensity information without unnecessarily and frequently interrupting communication between the wireless communication device 100 and the user terminal 200.

The radio wave intensity information acquisition unit 170 of the wireless communication device 100 according to the embodiment of the present disclosure is preferably provided between the user terminal 200 and the body surface of the user holding the user terminal 200 that faces the user terminal 200.

According to the above configuration, by attaching or including the radio wave intensity information acquisition unit 170 in an appropriate position, it becomes possible to appropriately measure the radio wave intensity from the base station 300 to the user terminal 200.

When a user uses a seat belt, the radio wave intensity information acquisition unit 170 of the wireless communication device 100 according to the sixth aspect of the present disclosure is preferably attached to at least one of the webbing, buckle, and retractor of the seat belt. When the radio wave intensity information acquisition unit 170 is attached to the webbing, it is preferable that the radio wave intensity information acquisition unit 170 is provided at least one of the webbing.

According to the above configuration, by attaching or including the radio wave strength information acquisition unit 170 at an appropriate position, it becomes possible to appropriately measure the radio wave strength from the base station 300 to the user terminal 200. In addition, by combining the radio wave strength information of multiple radio wave strength information acquisition units 170, it may become possible to further appropriately measure the radio wave strength from the base station 300 to the user terminal 200.

The directivity control unit 120 of the wireless communication device 100 according to the seventh aspect of the present disclosure preferably controls the directivity by controlling the phase input to the antenna element, or by controlling the phase and amplitude input to the antenna element.

The above configuration can be achieved not only by using a phased array antenna, but also by using an adaptive array antenna. It is possible to realize a configuration that suppresses wasteful power consumption by suppressing the radiation of unnecessary radio waves while maintaining communication quality.

A wireless communication system 1000 according to an eighth aspect of the present disclosure preferably includes a wireless communication device 100 according to any one of the first to eighth aspects, and an antenna unit ANT whose directivity is controlled by a directivity control unit 120 of the wireless communication device 100.

The above configuration makes it possible to reduce wasteful power consumption by appropriately selecting the type of antenna and suppressing the emission of unnecessary radio waves while maintaining communication quality.

The wireless communication system 1000 according to the present disclosure further includes a mobile body 10, and it is preferable that the wireless communication device 100 and the antenna unit ANT that communicates with the user terminal 200 are mounted on the mobile body 10.

With the above configuration, the user terminal 200 can maintain communication quality even inside the mobile body, and the wireless communication device inside the mobile body can reduce wasteful power consumption by suppressing the emission of unnecessary radio waves.

The block diagram of FIG. 3 used to explain the above-mentioned embodiment shows functional blocks. These functional blocks are realized by any combination of at least one of hardware and software. The method of realizing each functional block is not particularly limited. For example, each functional block may be realized using one device that is physically or logically coupled, or may be realized using two or more devices that are physically or logically separated and directly or indirectly connected to each other. The functional blocks may be realized by combining software with one device or multiple devices.

When the wireless communication device 100 is composed of multiple hardware elements, each functional block is realized by any one of the hardware elements or a combination of the hardware elements. Examples of hardware elements include a processor, memory, storage, a communication device, an input device, an output device, a bus, etc.

In this case, each function of the wireless communication device 100 is realized by loading a specific software or program onto hardware such as a processor and memory. Specifically, each function is realized by loading specific software onto the hardware, causing the processor to perform calculations and control the reading and writing of data in the memory and storage.

Although the embodiments have been described in detail with reference to the drawings, the present invention is not limited to the contents described in the above embodiments. Furthermore, the components described above include those that a person skilled in the art would easily imagine and those that are substantially the same. Furthermore, the configurations described above can be combined as appropriate. Furthermore, various omissions, substitutions, or modifications of the configuration can be made without departing from the spirit of the present invention.

REFERENCE SIGNS LIST 10 Mobile body 100 Wireless communication device 110 Transmission/reception processing unit 120 Directivity control unit 130 Control unit 131 Transmission/reception control unit 132 User position information control unit 133 Radio wave intensity information control unit 134 Operation control unit 140 Storage unit 141 Transmission/reception processing information storage unit 142 User position information storage unit 143 Radio wave intensity related information storage unit 150 I/F unit 160 User position information acquisition unit 170 Radio wave intensity information acquisition unit 180 Electronic device 200 User terminal 300 Base station 1000 Wireless communication system ANT Antenna unit

Claims (6)

In a wireless communication device capable of setting a plurality of directivities for transmitting and receiving radio waves,
a user position information acquisition unit that acquires position information of a user using a user terminal that is present inside a mobile body in which the wireless communication device is installed and that is to perform wireless communication with the wireless communication device;
a radio wave intensity information acquisition unit that acquires radio wave intensity information regarding the radio wave intensity of a radio wave radiated from a base station installed outside the mobile object to be received by the user terminal;
a directivity control unit that sets the directivity toward a position direction of the user when the radio wave intensity information is equal to or less than a predetermined threshold;
a transmission/reception processing unit for performing wireless communication with the user terminal,
When the radio wave intensity information exceeds the predetermined threshold, stopping operation of a directivity control unit and a transmission/reception processing unit for wireless communication with the user terminal ;
the user position information acquisition unit is a seating determination device that indicates whether the user is seated in a seat including a seat belt provided in the moving object, or an imaging device provided in the moving object,
the radio wave intensity information acquisition unit acquires the radio wave intensity information when the seating determination device determines that the user is seated or when the imaging device determines that the user is present inside the moving object,
The wireless communication device , wherein the radio wave strength information acquisition unit updates the radio wave strength information when the user's location information changes or for each allocated wireless communication processing period . The wireless communication device of claim 1, further comprising an operation control unit that stops wireless communication between the wireless communication device and all of the user terminals present inside the mobile body in which the wireless communication device is installed when the radio wave strength information acquisition unit acquires the radio wave strength information regarding the radio wave strength of radio waves emitted from a base station installed outside the mobile body. The wireless communication device according to claim 2, wherein, when the radio wave strength information indicates the reception strength of the radio wave received by the radio wave strength information acquisition unit, the radio wave strength information acquisition unit compares the maximum value of the reception strength of the received radio wave in the frequency band used by the user terminal with the predetermined threshold value. The wireless communication device according to claim 1 or 2, wherein the radio wave intensity information acquisition unit is attached to at least one of the webbing, buckle, and retractor of the seat belt when the user uses the seat belt, and is provided at at least one of the webbing when attached to the webbing. The wireless communication device according to claim 1 , wherein the directivity control unit controls the directivity by controlling a phase input to an antenna element, or by controlling the phase and amplitude input to an antenna element. A wireless communication device according to any one of claims 1 to 5 ,
an antenna unit whose directivity is controlled by the directivity control unit of the wireless communication device.

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