JP2020167545A - On-vehicle communication unit and communication method - Google Patents

Abstract

To provide an on-vehicle communication unit suitable for vehicle-to-vehicle communication and road-vehicle communication.SOLUTION: A communication unit 10 includes: a wireless communication module 20; and a control section 30 for controlling an operation of the wireless communication module 20. The wireless communication module 20 includes: a first transmission/reception section 21 that can selectively perform transmission/reception in vehicle-to-vehicle communication and road-vehicle communication via a first antenna 11; and a second transmission/reception section 22 that can selectively perform vehicle-to-vehicle communication and road-vehicle communication via a second antenna 12. The control section 30 controls the wireless communication module 20 so as to change over the first transmission/reception section 21 and the second transmission/reception section 22 between vehicle-to-vehicle communication and road-vehicle communication at predetermined changeover timing.SELECTED DRAWING: Figure 1

Description

The present invention relates to an in-vehicle communication device and a communication method.

In recent years, vehicle-to-vehicle communication that communicates between a plurality of vehicles and road-to-vehicle communication that communicates between a vehicle and a roadside machine installed on the road have been proposed. In the in-vehicle communication device used for these communications, it is preferable to perform a self-diagnosis to promptly detect an abnormality when it occurs and take appropriate measures.

Patent Documents 1 and 2 are known as background techniques in this technical field. In Patent Document 1, self-diagnosis is performed by repeatedly transmitting and receiving weak radio waves that cannot be received between a plurality of antennas at regular time intervals without passing through the antennas, and the weak radio waves are received in the event of an emergency such as failure or theft. An emergency call device having a self-diagnosis function that notifies the emergency call reception center of the occurrence of an emergency situation when it becomes impossible is disclosed. In Patent Document 2, in a wireless communication device equipped with wireless communication systems of a plurality of different wireless communication methods using the same frequency band, the communication period of each other with respect to the wireless communication systems of a plurality of wireless communication methods is set. Based on the result of detecting the radio waves from the wireless communication system in the free time and the time division control unit that allocates the communication period for each free time so that they do not overlap and performs the time division communication. , A wireless communication device characterized by including a diagnostic processing unit for diagnosing a failure of a wireless communication system is disclosed.

International Publication No. 00/07158 International Publication No. 2014/0847467

In the techniques described in Patent Documents 1 and 2, it is necessary to repeatedly transmit and receive radio waves between a plurality of antennas and a plurality of wireless communication devices at regular time intervals. Therefore, it is difficult to apply it as it is in a communication method such as vehicle-to-vehicle communication and road-to-vehicle communication in which there is not always a communication partner in the vicinity.
An object of the present invention is to provide an in-vehicle communication device suitable for vehicle-to-vehicle communication and road-to-vehicle communication in order to solve the above problems.

The in-vehicle communication device according to the present invention has a first transmission / reception unit capable of selectively transmitting / receiving a first wireless communication and a second wireless communication via the first antenna, and the first transmission / reception unit via the second antenna. The first wireless communication between a second transmission / reception unit capable of selectively transmitting / receiving 1 wireless communication and the second wireless communication, and the first transmission / reception unit and the second transmission / reception unit at predetermined timings. Alternatively, it includes a control unit for switching to the second wireless communication.
The communication method according to the present invention includes a first transmission / reception unit capable of selectively transmitting / receiving a first wireless communication and a second wireless communication via a first antenna, and the first transmission / reception unit via a second antenna. It is based on an in-vehicle communication device including a second transmission / reception unit capable of selectively transmitting / receiving wireless communication and the second wireless communication, and the first transmission / reception unit is set before a predetermined timing. The first radio communication is performed by using the first transmission / reception unit, the second radio communication is performed using the second transmission / reception unit, and after the timing, the second radio communication is performed using the first transmission / reception unit. And the first wireless communication is performed using the second transmission / reception unit.

According to the present invention, it is possible to provide an in-vehicle communication device suitable for vehicle-to-vehicle communication and road-to-vehicle communication.

It is a figure which shows the structure of the communication device which concerns on 1st Embodiment of this invention. It is a flowchart of abnormality diagnosis processing in the communication device which concerns on 1st Embodiment of the invention. It is a figure which shows the structure of the communication device which concerns on 2nd Embodiment of this invention. It is a flowchart of abnormality diagnosis processing in the communication device which concerns on 2nd Embodiment of this invention.

(First Embodiment)
FIG. 1 is a diagram showing a configuration of a communication device according to a first embodiment of the present invention. The communication device 10 shown in FIG. 1 is mounted on the vehicle body 1 and is used, and includes a wireless communication module 20, a control unit 30, a vehicle condition diagnosis unit 31, a notification unit 32, and a reception condition diagnosis unit 33. The communication device 10 is connected to, for example, a CAN (Controller Area Network) which is a communication network provided in the vehicle, and is connected to another information device (not shown) mounted on the vehicle body 1 via the CAN. Information can be input and output with. In the following, a vehicle having a vehicle body 1 on which the communication device 10 is mounted is referred to as a "own vehicle".

The wireless communication module 20 has a first transmission / reception unit 21 and a second transmission / reception unit 22. The first transmission / reception unit 21 and the second transmission / reception unit 22 are transmitters / receivers capable of selectively transmitting / receiving vehicle-to-vehicle communication and road-to-vehicle communication, respectively. Vehicle-to-vehicle communication is wireless communication performed between the own vehicle and another vehicle, and road-to-vehicle communication is wireless communication performed between the own vehicle and a roadside unit installed on the road. The wireless communication module 20 performs road-to-vehicle communication by the second transmission / reception unit 22 when the first transmission / reception unit 21 is performing vehicle-to-vehicle communication, and is second when the first transmission / reception unit 21 is performing road-to-vehicle communication. Vehicle-to-vehicle communication is performed by the transmission / reception unit 22. The first transmission / reception unit 21 and the second transmission / reception unit 22 switch the frequency channel of wireless communication according to the control of the control unit 30, for example, from vehicle-to-vehicle communication to road-to-vehicle communication, or from road-to-vehicle communication to vehicle-to-vehicle communication. You can switch to at any time.

The first transmission / reception unit 21 is connected to the first antenna 11 installed on the vehicle body 1, and performs vehicle-to-vehicle communication and road-to-vehicle communication via the first antenna 11. The second transmission / reception unit 22 is connected to the second antenna 12 installed on the vehicle body 1, and performs vehicle-to-vehicle communication and road-to-vehicle communication via the second antenna 12. The first antenna 11 and the second antenna 12 are respectively installed in the vehicle body 1 at positions and directions in which radio waves can be easily transmitted and received from other vehicles and roadside machines existing around the own vehicle. A plurality of first antennas 11 and a plurality of second antennas 12 may be installed so as to appropriately cover the communication range of vehicle-to-vehicle communication and road-to-vehicle communication.

The control unit 30 is a portion that controls the operation of the wireless communication module 20. The operation control of the wireless communication module 20 performed by the control unit 30 includes the above-mentioned switching control between vehicle-to-vehicle communication and road-to-vehicle communication performed on the first transmission / reception unit 21 and the second transmission / reception unit 22 in the wireless communication module 20. And the abnormality diagnosis processing of the first transmission / reception unit 21 and the second transmission / reception unit 22 are included.

The vehicle condition diagnosis unit 31 is a portion for diagnosing whether or not the own vehicle is in a specific state. The specific state is a state in which the own vehicle does not need to perform vehicle-to-vehicle communication or road-to-vehicle communication. For example, an activated state immediately after the ignition switch is turned on, a stopped state, a low-speed running state below a certain speed, and the like. This applies when the number of vehicles around the vehicle is less than a certain number. The vehicle condition diagnosis unit 31 diagnoses whether or not the own vehicle is in these states, and outputs the diagnosis result to the control unit 30. If it can be determined that the own vehicle does not need to perform vehicle-to-vehicle communication or road-to-vehicle communication, another state may be the diagnosis target of the vehicle state diagnosis unit 31.

The notification unit 32 is a portion that notifies the user who is an occupant of the own vehicle of the result of the abnormality diagnosis processing performed by the control unit 30 on the first transmission / reception unit 21 and the second transmission / reception unit 22. The notification unit 32 is connected to a display or speaker (not shown) installed in the vehicle body 1, and uses these to output a predetermined image or sound to notify the user.

The reception state diagnosis unit 33 measures the received power of the radio waves received by the first transmission / reception unit 21 and the second transmission / reception unit 22, and diagnoses the reception state of vehicle-to-vehicle communication and road-to-vehicle communication based on the measurement results. is there. For example, the reception state diagnosis unit 33 compares the measured value of the received power with a predetermined threshold value, and if it is less than the threshold value, determines that the reception state is abnormal. The reception state diagnosis unit 33 outputs the diagnosis result of the reception state to the control unit 30.

The control unit 30, the vehicle state diagnosis unit 31, the notification unit 32, and the reception state diagnosis unit 33 are configured by using, for example, a CPU, ROM, RAM, or the like (not shown). That is, in the communication device 10 of the present embodiment, the program stored in the ROM is expanded into the RAM and executed by the CPU, so that the control unit 30, the vehicle state diagnosis unit 31, the notification unit 32, and the reception state diagnosis unit 33 are executed. Each function can be realized.

FIG. 2 is a flowchart of an abnormality diagnosis process in the communication device according to the first embodiment of the present invention. In the present embodiment, the control unit 30 of the communication device 10 executes an abnormality diagnosis process of the first transmission / reception unit 21 and the second transmission / reception unit 22 according to the flowchart of FIG. 2 by executing a predetermined program, for example, in a CPU (not shown). Do.

In step S1, the control unit 30 starts from one of the first transmission / reception unit 21 and the second transmission / reception unit 22 currently used for vehicle-to-vehicle communication (hereinafter, referred to as “vehicle-side transmission / reception unit”). The transmitted radio wave is controlled to be received by the other transmitting / receiving unit (hereinafter referred to as "roadside transmitting / receiving unit") used for road-to-vehicle communication. For example, the reception channel of the roadside transmission / reception unit is changed so that the roadside transmission / reception unit can receive the radio wave in accordance with the transmission timing of the radio wave transmitted by the vehicle-side transmission / reception unit to another vehicle in the inter-vehicle communication. As a result, the roadside transmitter / receiver can receive the radio waves transmitted from the vehicle-side transmitter / receiver.

In step S2, the control unit 30 confirms whether or not there is a problem in the reception state of the roadside transmission / reception unit that received the radio wave in step S1. Here, the reception state diagnosis unit 33 measures the received power of the radio wave received by the roadside transmission / reception unit in step S1, and compares the measured value with a predetermined threshold value. As a result, if the measured value of the received power is equal to or more than the threshold value, it is determined that there is no problem in the reception state of the roadside transmitter / receiver, and the process proceeds to step S3. It is determined that the state is abnormal, and the process proceeds to step S6.

In step S3, the control unit 30 determines whether or not the preset switching timing has been reached. Here, the switching timing is determined according to the diagnosis result of the own vehicle state by the vehicle state diagnosis unit 31. Specifically, when the vehicle condition diagnosis unit 31 diagnoses a specific state as described above, that is, a state in which the own vehicle does not need to perform vehicle-to-vehicle communication or road-to-vehicle communication, it is said that the switching timing has come. It is determined and the process proceeds to step S4. If not, it is determined that the switching timing has not been reached and the process proceeds to step S5.

In step S4, the control unit 30 switches the functions of the first transmission / reception unit 21 and the second transmission / reception unit 22 to each other. That is, if the first transmission / reception unit 21 has operated as the vehicle-side transmission / reception unit and the second transmission / reception unit 22 has operated as the roadside transmission / reception unit, the first transmission / reception unit 21 will be operated as the roadside transmission / reception unit in the future. , The second transmission / reception unit 22 is controlled to operate as a vehicle-side transmission / reception unit. As a result, the function of the first transmission / reception unit 21 is switched from vehicle-to-vehicle communication to road-to-vehicle communication, while the function of the second transmission / reception unit 22 is switched from road-to-vehicle communication to vehicle-to-vehicle communication. On the contrary, if the first transmission / reception unit 21 has operated as the roadside transmission / reception unit and the second transmission / reception unit 22 has operated as the vehicle-side transmission / reception unit, the first transmission / reception unit 21 will be used as the vehicle-side transmission / reception unit in the future. In addition to operating, the second transmission / reception unit 22 is controlled to operate as a roadside transmission / reception unit. As a result, the function of the first transmission / reception unit 21 is switched from road-to-vehicle communication to vehicle-to-vehicle communication, while the function of the second transmission / reception unit 22 is switched from vehicle-to-vehicle communication to road-to-vehicle communication.

In step S5, the control unit 30 determines whether or not a certain time interval has elapsed since the determination that the switching timing has not occurred in step S3, and stays in step S5 until a certain time interval elapses. The fixed time interval used in the determination in step S5 is provided to adjust the frequency at which the abnormality diagnosis process is executed in the communication device 10, and an arbitrary value can be set. .. The determination in step S5 may be omitted, and the abnormality diagnosis process may be sequentially executed.

After the switching control between vehicle-to-vehicle communication and road-to-vehicle communication is completed in step S4, or after it is determined in step S5 that a certain time interval has elapsed, the process returns to step S1 and the above process is repeated.

In step S6, the control unit 30 uses the notification unit 32 to notify the user of the notification based on the diagnosis result of the reception state performed in step S2. For example, the user is notified by a predetermined screen display, voice output, special character display, or the like that the inter-vehicle communication has been interrupted by either the first transmission / reception unit 21 or the second transmission / reception unit 22. At this time, if vehicle-to-vehicle communication or road-to-vehicle communication is used for automatic driving control of the own vehicle, the user may be notified that the automatic driving is canceled and the manual driving is started. After notifying the user in step S6, the flowchart of FIG. 2 ends.

According to the first embodiment of the present invention described above, the following effects are exhibited.

(1) The communication device 10 includes a first transmission / reception unit 21 capable of selectively transmitting / receiving a first wireless communication (vehicle-to-vehicle communication) and a second wireless communication (road-to-vehicle communication) via the first antenna 11. The second transmission / reception unit 22 capable of selectively transmitting / receiving the first wireless communication and the second wireless communication via the second antenna 12, and the first transmission / reception unit 21 and the second transmission / reception unit 22 are second at predetermined timings. A control unit 30 for switching to the wireless communication of 1 or the second wireless communication (steps S3 to S4) is provided. Since this is done, it is possible to provide an in-vehicle communication device suitable for vehicle-to-vehicle communication and road-to-vehicle communication.

(2) One of the first transmission / reception unit 21 and the second transmission / reception unit 22 (vehicle-side transmission / reception unit) transmits radio waves by the first wireless communication (vehicle-to-vehicle communication), and the first transmission / reception unit 21 or The other transmission / reception unit (roadside transmission / reception unit) of the second transmission / reception unit 22 receives the radio wave transmitted by the first wireless communication from the vehicle-side transmission / reception unit (step S1). The control unit 30 performs an abnormality diagnosis based on the radio waves received by the roadside transmission / reception unit (step S2). Since this is done, it is possible to perform an abnormality diagnosis suitable for vehicle-to-vehicle communication and road-to-vehicle communication.

(3) The communication device 10 includes a reception state diagnosis unit 33 that measures the received power of the radio wave received by the roadside transmission / reception unit. In step S2, the control unit 30 performs an abnormality diagnosis based on the received power measured by the reception state diagnosis unit 33. Since this is done, abnormality diagnosis can be performed with a simple configuration.

(4) The communication device 10 includes a notification unit 32 that gives a predetermined notification when it is diagnosed that there is an abnormality in the abnormality diagnosis in step S2 (step S6). Since this is done, when an abnormality occurs, it is possible to immediately notify the user and prompt an appropriate countermeasure.

(5) The switching timing used in step S3 is the timing when the own vehicle on which the communication device 10 is mounted is in a predetermined state. Therefore, it is possible to easily set an appropriate switching timing according to the state of the own vehicle.

(Second Embodiment)
Next, a second embodiment of the present invention will be described. In the present embodiment, an example will be described in which vehicle-to-vehicle communication and road-to-vehicle communication are continuously performed even when an abnormality occurs in the first transmission / reception unit 21 or the second transmission / reception unit 22.

FIG. 3 is a diagram showing a configuration of a communication device according to a second embodiment of the present invention. The communication device 10A shown in FIG. 3 is mounted on the vehicle body 1 and used in the same manner as the communication device 10 described in the first embodiment. The communication device 10A is different from the communication device 10 described in the first embodiment in that it further includes a map information storage unit 34. Of the communication device 10A in the present embodiment, the components other than the map information storage unit 34 are the same as those in FIG. 1 described in the first embodiment, and thus the description thereof will be omitted below.

The map information storage unit 34 stores and holds map information of each area in which the own vehicle can travel. This map information includes the position information of each roadside aircraft installed at various points on and around the road. The control unit 30 reads and acquires map information representing the vicinity of the current position of the own vehicle from the map information storage unit 34, thereby determining the presence or absence of a roadside machine in the vicinity of the own vehicle and the position of the roadside machine if it exists. And can be grasped.

In the example of FIG. 3, the map information storage unit 34 is provided in the communication device 10A, but the map information storage unit 34 may not be provided in the communication device 10A. For example, a navigation device mounted on the own vehicle, an external server, or the like may be used as the map information storage unit 34, and map information around the own vehicle may be acquired from these.

FIG. 4 is a flowchart of the abnormality diagnosis process in the communication device according to the second embodiment of the present invention. In the present embodiment, the control unit 30 of the communication device 10A executes an abnormality diagnosis process of the first transmission / reception unit 21 and the second transmission / reception unit 22 according to the flowchart of FIG. 4 by executing a predetermined program, for example, in a CPU (not shown). Do.

In steps S1 to S6, the same processes as those in the flowchart of FIG. 2 described in the first embodiment are performed.

In step S7, the control unit 30 acquires the map information around the own vehicle from the map information storage unit 34.

In step S8, the control unit 30 determines whether or not the roadside machine exists within a predetermined distance from the own vehicle based on the map information acquired in step S7. As a result, if at least one roadside machine exists within a predetermined distance, the process proceeds to step S9, and if none of the roadside machines exist, the process returns to step S7 to continue acquiring map information.

In step S9, the control unit 30 uses the normal transmission / reception unit of the first transmission / reception unit 21 or the second transmission / reception unit 22 to perform vehicle-to-vehicle communication and road-to-vehicle communication in a time-division manner. To control. Here, for example, of the first transmission / reception unit 21 or the second transmission / reception unit 22, the one that is the roadside transmission / reception unit in step S1 is determined as the normal transmission / reception unit. Alternatively, as in step S4, after switching the functions of the first transmission / reception unit 21 and the second transmission / reception unit 22 to replace the vehicle-side transmission / reception unit and the roadside transmission / reception unit, the same processing as in steps S1 and S2 is performed again. The normal transmission / reception unit may be determined in consideration of these processing results. After determining the normal transmission / reception unit in this way, the control unit 30 sets the time allocated to the vehicle-to-vehicle communication and the road-to-vehicle communication within a predetermined communication cycle, and the transmission / reception unit performs the vehicle-to-vehicle communication according to the set allocation time. And control so that road-to-vehicle communication is performed in a time-division manner. At this time, the allocated time may be adjusted according to the number of other vehicles and roadside vehicles existing around the own vehicle. After performing the process of step S9, the flowchart of FIG. 4 ends.

According to the second embodiment of the present invention described above, when the communication device 10A is diagnosed as having an abnormality in one of the first transmission / reception unit 21 and the second transmission / reception unit 22 in the abnormality diagnosis in step S2. The first wireless communication (vehicle-to-vehicle communication) and the second wireless communication (road-to-vehicle communication) are performed in a time-division manner using the other transmission / reception unit (step S9). Since this is done, even if an abnormality occurs in the first transmission / reception unit 21 or the second transmission / reception unit 22, vehicle-to-vehicle communication and road-to-vehicle communication can be continuously performed.

Further, according to the second embodiment of the present invention described above, the control unit 30 acquires map information around the own vehicle on which the communication device 10A is mounted (step S7), and is based on the acquired map information. Then, the other transmitting / receiving unit determines the timing at which the first wireless communication and the second wireless communication are performed in a time-division manner (step S9). Since this is done, the vehicle-to-vehicle communication and the road-to-vehicle communication can be performed in a time-division manner at the timing when the road-to-vehicle communication with the roadside units existing around the own vehicle is required.

The first and second embodiments described above may be modified as follows.

(Modification example 1)
The abnormality diagnosis of the first transmission / reception unit 21 and the second transmission / reception unit 22 may not be performed, and only the switching of these functions may be performed. For example, by performing only the processes of steps S3 and S4 in the flowcharts of FIGS. 2 and 4, the functions of the first transmission / reception unit 21 and the second transmission / reception unit 22 can be switched to each other at predetermined switching timings. In this way, the loads of vehicle-to-vehicle communication and road-to-vehicle communication can be distributed between the first transmission / reception unit 21 and the second transmission / reception unit 22, and the loads can be equalized to each other. Therefore, it is possible to reduce the probability that a failure will occur in the communication devices 10 and 10A as compared with the conventional communication device that does not perform such processing.

(Modification 2)
In the first and second embodiments, an example of switching between vehicle-to-vehicle communication and road-to-vehicle communication between the first transmission / reception unit 21 and the second transmission / reception unit 22 has been described, but the communication method to be switched by the present invention has been described. Is not limited to this. The present invention is provided as long as it includes a plurality of transmission / reception units capable of selectively performing a plurality of types of wireless communication, and the types of wireless communication performed by each transmission / reception unit can be switched between each other at a predetermined switching timing. Included in the scope of application.

The embodiments and various modifications described above are merely examples, and the present invention is not limited to these contents as long as the features of the invention are not impaired. Further, the above-described embodiment and the modified example may be used in any combination.

10, 10A: Communication device, 11: 1st antenna, 12: 2nd antenna, 20: Wireless communication module, 21: 1st transmission / reception unit, 22: 2nd transmission / reception unit, 30: Control unit, 31: Vehicle condition diagnosis unit , 32: Notification unit, 33: Reception status diagnosis unit, 34: Map information storage unit

Claims (9)

A first transmitter / receiver capable of selectively transmitting / receiving a first wireless communication and a second wireless communication via the first antenna,
A second transmission / reception unit capable of selectively transmitting / receiving the first wireless communication and the second wireless communication via the second antenna.
An in-vehicle communication device comprising: a control unit for switching between the first transmission / reception unit and the second transmission / reception unit at a predetermined timing to the first wireless communication or the second wireless communication. In the in-vehicle communication device according to claim 1,
One of the first transmission / reception unit or the second transmission / reception unit transmits radio waves in the first wireless communication.
The other transmission / reception unit of the first transmission / reception unit or the second transmission / reception unit receives the radio wave transmitted by the first wireless communication from the one transmission / reception unit, and receives the radio wave.
The control unit is an in-vehicle communication device, characterized in that an abnormality diagnosis is performed based on the radio wave received by the other transmission / reception unit. In the in-vehicle communication device according to claim 2,
A reception state diagnosis unit that measures the received power of the radio wave received by the other transmission / reception unit
The control unit is an in-vehicle communication device that performs the abnormality diagnosis based on the received power measured by the reception state diagnosis unit. In the in-vehicle communication device according to claim 2 or 3,
An in-vehicle communication device including a notification unit that gives a predetermined notification when an abnormality is diagnosed by the abnormality diagnosis. In the in-vehicle communication device according to any one of claims 2 to 4.
When one of the first transmission / reception unit or the second transmission / reception unit is diagnosed as abnormal in the abnormality diagnosis, the control unit uses the other transmission / reception unit to perform the first wireless communication and An in-vehicle communication device characterized in that the second wireless communication is performed in a time-division manner. In the in-vehicle communication device according to claim 5,
The control unit acquires map information around the vehicle on which the in-vehicle communication device is mounted, and based on the acquired map information, the other transmission / reception unit performs the first wireless communication and the second wireless communication. An in-vehicle communication device characterized in that the timing of performing wireless communication in a time-division manner is determined. In the in-vehicle communication device according to any one of claims 1 to 6.
The predetermined timing is a timing at which the vehicle on which the vehicle-mounted communication device is mounted is in a predetermined state. In the in-vehicle communication device according to any one of claims 1 to 7.
The first wireless communication is vehicle-to-vehicle communication, and is
The second wireless communication is an in-vehicle communication device characterized by road-to-vehicle communication. A first transmission / reception unit capable of selectively transmitting / receiving a first wireless communication and a second wireless communication via a first antenna, and the first wireless communication and the second wireless communication via a second antenna. It is a communication method using an in-vehicle communication device equipped with a second transmission / reception unit capable of selectively transmitting / receiving wireless communication.
Prior to a predetermined timing, the first transmission / reception unit is used to perform the first wireless communication, and the second transmission / reception unit is used to perform the second wireless communication.
A communication method characterized in that after the timing, the first transmission / reception unit is used to perform the second wireless communication, and the second transmission / reception unit is used to perform the first wireless communication.

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