Vehicle-to-Vehicle Communication System, On-Vehicle Unit, Communication Method, and Program

Abstract

To provide a vehicle-to-vehicle communication system, an on-vehicle device, a communication method, and a program that can switch between narrow-area vehicle-to-vehicle communication and cellular communication.SOLUTION: A first on-vehicle device includes: a first vehicle-to-vehicle communication unit; a first mobile communication unit; a first creation unit that creates a first message including a message to a second vehicle; and a first communication control unit that causes the first vehicle-to-vehicle communication unit to transmit the first message created by the first creation unit. A second on-vehicle device includes: a second vehicle-to-vehicle communication unit; a second mobile communication unit; a second creation unit that creates a first response message to the first message received by the second vehicle-to-vehicle communication unit; and a second communication control unit that causes the second vehicle-to-vehicle communication unit or the second mobile communication unit to transmit the first response message created by the second creation unit, based on identification information on vehicles surrounding the first vehicle included in the first message and identification information on vehicles surrounding the second vehicle.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to an inter-vehicle communication system, an in-vehicle device, a communication method, and a program.

Background Art

[0002] In ITS (Intelligent Transport Systems) (Advanced Road Traffic Systems), it is expected that vehicles will utilize dynamic information such as traffic information on accidents and traffic jams, and signal information, to assist the operation of autonomous vehicles and improve driving comfort and convenience. In a DSRC (Dedicated Short Range Communications) (narrowband communication) system using the 5.8 GHz band, an ITS Connect system using the 760 MHz band, a cellular V2X (C-V2X: Cellular Vehicle to Everything) PC5 communication system defined in 3GPP Release 14, etc., which are called V2V (Vehicle to Vehicle) communication (inter-vehicle communication), information such as position information and other driving information is periodically diffused from each vehicle to the surroundings, thereby realizing information exchange such as position information between vehicles. As a result, each vehicle grasps the mutual position information and is utilized in a danger detection system at intersections and the like. A method of performing communication via a cellular network such as LTE through network facilities and a base station (BS) for V2V communication is called V2N2V (abbreviation of Vehicle to Network to Vehicle) communication. Regarding these communication systems, a technique of performing information exchange between vehicles by periodically diffusing position information and other driving information from each vehicle to the surroundings is known (see, for example, Patent Document 1). By using this technique, the positional relationship of each vehicle can be grasped.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In short-range vehicle-to-vehicle communication (V2V) such as the aforementioned DSRC, ITS Connect, and C-V2X PC5, the communication range is several tens to several hundreds of meters. For this reason, in short-range V2V, communication with vehicles at a long distance may not be possible. Also, in short-range V2V, since it is direct communication, the communication delay is small, but due to the presence of obstacles such as buildings, communication may not be possible. In short-range V2V, basically one-to-many broadcast communication is performed, so reach confirmation is not performed. That is, in short-range V2V, the transmitting side transmits information without specifying a communication partner, and the receiving side determines the selection and service implementation of the information. On the other hand, since V2N2V communication uses cellular communication such as LTE, the reliability of communication is high, and the communication range is also wide because communication is possible within the base station area. However, since it uses resources shared with other cellular communications such as smartphones, if a large number of communications are performed, it will impose a heavy burden on the communication carrier's facilities. The present invention has been made to solve the above problems, and an object thereof is to provide a vehicle-to-vehicle communication system, an in-vehicle device, a communication method, and a program that can switch between short-range vehicle-to-vehicle communication (V2V) and communication via a cellular network (V2N2V).

Means for Solving the Problems

[0005] (1) One aspect of the present invention is an inter-vehicle communication system including a first in-vehicle device mounted on a first vehicle and a second in-vehicle device mounted on a second vehicle. The first in-vehicle device includes a first inter-vehicle communication unit that communicates with a vehicle, a first mobile communication unit that communicates using a mobile communication network, a first creation unit that creates a first message including a message to the second vehicle, and a first communication control unit that causes the first inter-vehicle communication unit to transmit the first message created by the first creation unit. The second in-vehicle device includes a second inter-vehicle communication unit that communicates with a vehicle, a second mobile communication unit that communicates using a mobile communication network, a second creation unit that creates a first response message for the first message received by the second inter-vehicle communication unit, and based on the identification information of the vehicles around the first vehicle included in the first message and the identification information of the vehicles around the second vehicle, the second inter-vehicle communication unit or the second mobile communication unit Select and a second communication control unit that causes the second inter-vehicle communication unit to transmit the first response message created by the second creation unit. It is an inter-vehicle communication system. (2) One aspect of the present invention is that in the vehicle-to-vehicle communication system described in (1) above, the second communication control unit selects the second vehicle-to-vehicle communication unit or the second mobile communication unit based on a comparison result between the identification information of the vehicles around the first vehicle and the identification information of the vehicles around the second vehicle. ( 3 ) One aspect of the present invention is the inter-vehicle communication system described in the above (1) Or the above (2) . In the inter-vehicle communication system, the first creation unit creates a second message including a message to the second vehicle for the first response message. The first communication control unit causes the first inter-vehicle communication unit or the first mobile communication unit to transmit the second message created by the first creation unit based on the identification information of the vehicles around the second vehicle included in the first response message and the identification information of the vehicles around the first vehicle. The second creation unit creates a second response message for the second message, and the second communication control unit causes the second inter-vehicle communication unit or the second mobile communication unit to transmit the second response message created by the second creation unit based on the identification information of the vehicles around the first vehicle included in the second message and the identification information of the vehicles around the second vehicle. ( 4 ) One aspect of the present invention is the above (1) From above ( 3 ) Any one item In the vehicle-to-vehicle communication system described in , the first in-vehicle unit acquires the identification information of other vehicles, the position information of other vehicles, and the time information when the position information was measured, which are included in the position exchange information received by the first vehicle-to-vehicle communication unit, and stores, in a first storage unit, peripheral vehicle information in which the acquired identification information of other vehicles, the position information of other vehicles, and the time information when the position information was measured are associated. The first creation unit creates identification information of vehicles around the first vehicle including the identification information of one or more other vehicles included in the peripheral vehicle information stored in the first storage unit, and creates a first message including the created identification information of vehicles around the first vehicle. The second in-vehicle unit acquires the identification information of other vehicles, the position information of other vehicles, and the time information when the position information was measured, which are included in the position exchange information received by the second vehicle-to-vehicle communication unit, and stores, in a second storage unit, peripheral vehicle information in which the acquired identification information of other vehicles, the position information of other vehicles, and the time information when the position information was measured are associated. The second communication control unit causes the second vehicle-to-vehicle communication unit or the second mobile communication unit to transmit the first response message created by the second creation unit to the first vehicle based on the identification information of vehicles around the first vehicle included in the first message and the identification information of vehicles around the second vehicle included in the peripheral vehicle information stored in the second storage unit. ( 5 )One aspect of the present invention is, in the vehicle-to-vehicle communication system described in the above ( 4 ), the first processing unit updates the peripheral vehicle information stored in the first storage unit based on the time information when the position information was measured, and the second processing unit updates the peripheral vehicle information stored in the second storage unit based on the time information when the position information was measured. ( 6 )One aspect of the present invention is, from the above (1) to the above ( 5In the vehicle-to-vehicle communication system according to any one of the above, the second communication control unit causes the second vehicle-to-vehicle communication unit to transmit the first response message when the matching rate between the identification information of the vehicles around the first vehicle and the identification information of the vehicles around the second vehicle is equal to or higher than a threshold value, based on the identification information of the vehicles around the first vehicle and the identification information of the vehicles around the second vehicle, and causes the second mobile communication unit to transmit the first response message when the matching rate is less than the threshold value. ( 7 )One aspect of the present invention is, in the vehicle-to-vehicle communication system described in the above ( 6 ) that the second communication control unit changes the threshold value based on the number of the identification information of the vehicles around the second vehicle.

[0006] ( 8 )One aspect of the present invention is an in-vehicle device mounted on a vehicle, including a vehicle-to-vehicle communication unit that communicates with a vehicle, a mobile communication unit that communicates using a mobile communication network, a creation unit that creates a response message for a message transmitted by another in-vehicle device mounted on another vehicle received by the vehicle-to-vehicle communication unit, and based on the identification information of the vehicles around the other vehicle included in the message and the identification information of the vehicles around the vehicle, the vehicle-to-vehicle communication unit or the mobile communication unit Select , and a communication control unit that causes the communication control unit to transmit the response message created by the creation unit.

[0007] ( 9)One aspect of the present invention is a communication method executed by an inter-vehicle communication system including a first in-vehicle device mounted on a first vehicle and a second in-vehicle device mounted on a second vehicle. The first in-vehicle device includes a first inter-vehicle communication unit that communicates with a vehicle and a first mobile communication unit that communicates using a mobile communication network. The second in-vehicle device includes a second inter-vehicle communication unit that communicates with a vehicle and a second mobile communication unit that communicates using a mobile communication network. The communication method includes a step of the first in-vehicle device creating a first message including a message to the second vehicle, a step of the first in-vehicle device causing the first inter-vehicle communication unit to transmit the first message, a step of the second in-vehicle device creating a first response message to the first message received by the second inter-vehicle communication unit, and based on the identification information of the vehicles around the first vehicle included in the first message and the identification information of the vehicles around the second vehicle, the second inter-vehicle communication unit or the second mobile communication unit Select a step of causing the first response message to be transmitted. The communication method is as described above.

[0008] ( 10 )One aspect of the present invention is a communication method executed by an in-vehicle device mounted on a vehicle. The in-vehicle device includes an inter-vehicle communication unit that communicates with a vehicle and a mobile communication unit that communicates using a mobile communication network. The communication method includes a step of creating a response message to a message transmitted by another in-vehicle device mounted on another vehicle received by the inter-vehicle communication unit, and based on the identification information of the vehicles around the other vehicle included in the message and the identification information of the vehicles around the vehicle, the inter-vehicle communication unit or the mobile communication unit Select a step of causing the response message created in the creating step to be transmitted. The communication method is as described above.

[0009] ( 11)One aspect of the present invention is to cause a computer of an in-vehicle device including an inter-vehicle communication unit that communicates with other vehicles and a mobile communication unit that communicates using a mobile communication network to create a response message for a message transmitted by another in-vehicle device mounted on another vehicle received by the inter-vehicle communication unit, and based on the identification information of the vehicles around the other vehicle included in the message and the identification information of the vehicles around the vehicle, the inter-vehicle communication unit or the mobile communication unit Select to transmit the response message created in the step of creating. This is a program.

Advantages of the Invention

[0010] According to an embodiment of the present invention, it is possible to provide an inter-vehicle communication system, an in-vehicle device, a communication method, and a program that can switch between narrow-range vehicle-to-vehicle communication (V2V) and cellular communication (V2N2V).

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Modes for Carrying Out the Invention

[0012] Next, the vehicle-to-vehicle communication system, in-vehicle device, communication method, and program of the present embodiment will be described with reference to the drawings. The embodiments described below are merely examples, and the embodiments to which the present invention is applied are not limited to the following embodiments. In all the drawings for explaining the embodiments, those having the same function are denoted by the same reference numerals, and repeated explanations are omitted. In addition, as used in this application, "based on XX" means "based at least on XX", and includes cases where it is based on another element in addition to XX. Also, "based on XX" is not limited to the case where XX is directly used, and includes cases where it is based on something obtained by performing operations or processing on XX. "XX" is an arbitrary element (for example, arbitrary information).

[0013] (Embodiment) (Vehicle-to-vehicle communication system) FIG. 1 is a diagram showing an example of a vehicle-to-vehicle communication system according to an embodiment of the present invention. The vehicle-to-vehicle communication system 1 of the present embodiment includes a vehicle 100-A, a vehicle 100-B, a vehicle 100-C, and a server 300. Each of the vehicles 100-A, 100-B, and 100-C is equipped with an in-vehicle device, and the in-vehicle device includes a vehicle-to-vehicle communication unit that communicates with the vehicle and a mobile communication unit that communicates with the server 300 using a mobile communication network. Each of the vehicles 100-A, 100-B, and 100-C exchanges position information with other vehicles through short-range vehicle-to-vehicle communication (V2V) by the vehicle-to-vehicle communication unit. The vehicle-to-vehicle communication unit includes a short-range vehicle-to-vehicle communication interface. The vehicle-to-vehicle communication unit transmits vehicle exchange information including first vehicle information, which is information associating the identification information of the own vehicle, the position information of the own vehicle, and the time information when the position of the own vehicle was measured, at a first period such as 100 ms. Here, the vehicle exchange information is information for exchanging mutual position information between vehicles. In addition, the vehicle-to-vehicle communication unit receives vehicle exchange information transmitted by other vehicles. The vehicle exchange information transmitted by other vehicles includes first vehicle information that associates the identification information of the other vehicle, the position information of the other vehicle, and the time information when the position of the other vehicle was measured. When each of vehicle 100-A, vehicle 100-B, and vehicle 100-C receives the vehicle exchange information transmitted by other vehicles, it associates the identification information of the other vehicle, the position information of the other vehicle, and the time information when the position of the other vehicle was measured included in the received vehicle exchange information, and stores it as surrounding vehicle information. In the example shown in FIG. 1, vehicle 100-B is located in area A1 where vehicle-to-vehicle communication with vehicle 100-A is possible. That is, vehicle 100-B can receive the vehicle exchange information transmitted by vehicle 100-A, and vehicle 100-A can receive the vehicle exchange information transmitted by vehicle 100-B. Vehicle 100-B associates and stores the identification information of vehicle 100-A, the position information of vehicle 100-A, and the time information when the position of vehicle 100-A was measured included in the received vehicle exchange information. Vehicle 100-A associates and stores the identification information of vehicle 100-B, the position information of vehicle 100-B, and the time information when the position of vehicle 100-B was measured included in the received vehicle exchange information. In this case, the position information of each other is shared between vehicle 100-A and vehicle 100-B.

[0014] Each of vehicle 100-A, vehicle 100-B, and vehicle 100-C exchanges location information (V2N2V) with other vehicles via a mobile communication network using server 300 through its mobile communication unit. Specifically, each in-vehicle unit of vehicle 100-A, vehicle 100-B, and vehicle 100-C creates a vehicle information registration request that includes first vehicle information associating the identification information of its own vehicle it stores, the location information of its own vehicle, and the time information when the location of its own vehicle was measured, second vehicle information associating the identification information of one or more other vehicles it stores and the time information when the locations of the one or more other vehicles were measured, and the identification information of the user communicating using the mobile communication network, and sends the vehicle information registration request to server 300. Each in-vehicle unit of vehicle 100-A, vehicle 100-B, and vehicle 100-C sends the created vehicle information registration request at a second period such as 1000 ms. That is, each in-vehicle unit of vehicle 100-A, vehicle 100-B, and vehicle 100-C sends a vehicle information registration request to server 300 at a second period longer than the first period for sending vehicle exchange information. Here, the vehicle information registration request is information for a vehicle to register location information with server 300.

[0015] Server 300 receives the vehicle information registration requests sent by each in-vehicle unit of vehicle 100-A, vehicle 100-B, and vehicle 100-C, obtains the first vehicle information included in the received vehicle information registration requests, and stores by associating the identification information of the vehicle, the location information of the vehicle, and the time information when the location of the vehicle was measured included in the obtained first vehicle information. That is, each in-vehicle unit of vehicle 100-A, vehicle 100-B, and vehicle 100-C performs location registration with server 300. After each in-vehicle unit of vehicle 100-A, vehicle 100-B, and vehicle 100-C performs location registration with server 300, each in-vehicle unit of vehicle 100-A, vehicle 100-B, and vehicle 100-C continues to send vehicle information registration requests at the second period. When server 300 receives the vehicle information registration requests sent by each in-vehicle unit of vehicle 100-A, vehicle 100-B, and vehicle 100-C, it obtains the first vehicle information and the second vehicle information included in each of the received multiple vehicle information registration requests.

[0016] Based on the vehicle identification information, location information, and time information at which the location of each of the acquired plurality of first vehicle information was measured, the server 300 updates the location information of the vehicle 100-A stored, the time information at which the location of the vehicle 100-A was measured, the location information of the vehicle 100-B, the time information at which the location of the vehicle 100-B was measured, the location information of the vehicle 100-C, and the time information at which the location of the vehicle 100-C was measured. The server 300 identifies one or more other vehicle identification information other than the one or more other vehicle identification information included in the acquired second vehicle information among the one or more other vehicle identification information stored. The server 300 selects the one or more other vehicle identification information identified from the stored information, the one or more other vehicle location information associated with the one or more other vehicle identification information, and the time information at which the location of the one or more other vehicles was measured. The server 300 creates first notification information associating the selected one or more other vehicle identification information, the one or more other vehicle location information, and the time information at which the location of the one or more other vehicles was measured. The server 300 identifies one or more other vehicle identification information that is the same as the one or more other vehicle identification information included in the acquired second vehicle information from the one or more other vehicle identification information stored. The server 300 compares the time information at which the location of the other vehicle associated with each of the identified one or more other vehicle identification information stored was measured with the time information at which the location of the other vehicle included in the second vehicle information was measured, and based on the comparison result, creates second notification information associating the location information of the other vehicle associated with each of the identified one or more other vehicle identification information and the time information at which the location of the other vehicle was measured.

[0017] The server 300 identifies all of the identification information of the vehicles stored therein other than the identification information of the own vehicle 100-A and the identification information of one or more other vehicles included in the vehicle information registration request transmitted by the vehicle 100-A among the identification information of one or more vehicles stored. The server 300 creates first notification information which is information associating the identified identification information of one or more vehicles, the position information of the one or more vehicles associated with the identification information of the one or more vehicles, and the time information when the positions of the one or more vehicles were measured. The server 300 creates a vehicle information registration response addressed to the vehicle 100-A, including the created first notification information and second notification information, and transmits the created vehicle information registration response to the in-vehicle unit of the vehicle 100-A. The server 300 performs the same processing for the vehicle information registration request transmitted by the vehicle 100-B and the vehicle information registration request transmitted by the vehicle 100-C among the identification information of one or more vehicles stored.

[0018] As an example of communication between any two of the vehicles 100-A, 100-B, and 100-C, communication between the vehicle 100-A and the vehicle 100-B will be described. The same applies to communication between the vehicle 100-A and the vehicle 100-C and communication between the vehicle 100-B and the vehicle 100-C. The in-vehicle unit of the vehicle 100-A creates a message A including the identification information of the vehicles around the vehicle 100-A and a message to the vehicle 100-B. In the in-vehicle unit of the vehicle 100-A, the vehicle-to-vehicle communication unit transmits the message A to the vehicle 100-B. In the in-vehicle unit of the vehicle 100-B, the vehicle-to-vehicle communication unit receives the message A transmitted by the in-vehicle unit of the vehicle 100-A. The in-vehicle unit of the vehicle 100-B creates a response message AR for the message A received by the vehicle-to-vehicle communication unit. The response message AR includes the identification information of the vehicles around the vehicle 100-B and a message to the vehicle 100-A. The in-vehicle unit of the vehicle 100-B causes the vehicle-to-vehicle communication unit or the mobile communication unit to transmit the response message AR based on the identification information of the vehicles around the vehicle 100-A included in the message A and the identification information of the vehicles around the vehicle 100-B. In the in-vehicle device of vehicle 100-A, the vehicle-to-vehicle communication unit or the mobile communication unit receives the response message AR transmitted by the in-vehicle device of vehicle 100-B. The in-vehicle device of vehicle 100-A creates message B for the received response message AR. Message B includes the identification information of the vehicles around vehicle 100-A and the message to vehicle 100-B. The in-vehicle device of vehicle 100-A causes the vehicle-to-vehicle communication unit or the mobile communication unit to transmit request message B based on the identification information of the vehicles around vehicle 100-B included in the response message AR and the identification information of the vehicles around vehicle 100-A. In the in-vehicle device of vehicle 100-B, the vehicle-to-vehicle communication unit or the mobile communication unit receives message B transmitted by the in-vehicle device of vehicle 100-A. The in-vehicle device of vehicle 100-B creates response message BR for the received message B. Response message BR includes the identification information of the vehicles around vehicle 100-B and the message to vehicle 100-A. The in-vehicle device of vehicle 100-B causes the vehicle-to-vehicle communication unit or the mobile communication unit to transmit response message BR based on the identification information of the vehicles around vehicle 100-A included in message B and the identification information of the vehicles around vehicle 100-B. In the in-vehicle device of vehicle 100-A, the vehicle-to-vehicle communication unit or the mobile communication unit receives the response message BR transmitted by the in-vehicle device of vehicle 100-B. Hereinafter, any vehicle from vehicle 100-A to vehicle 100-C is described as vehicle 100.

[0019] Next, vehicle 100-A, vehicle 100-B, and server 300 will be described in detail. FIG. 2 is a diagram showing an example of an in-vehicle device and a server constituting the vehicle-to-vehicle communication system according to an embodiment of the present invention. Vehicle 100-A includes in-vehicle device 150A. In-vehicle device 150A includes positioning unit 102A, information processing unit 104A, vehicle-to-vehicle communication unit 106A, mobile communication unit 110A, and storage unit 108A. Positioning unit 102A is realized by a positioning system such as the Global Positioning System (GPS). Positioning unit 102A measures the position of vehicle 100-A in the first cycle. The vehicle-to-vehicle communication unit 106A is realized by a communication module. Specifically, the vehicle-to-vehicle communication unit 106A is composed of a wireless device that performs wireless communication between vehicles using narrowband wireless communication using ITS dedicated frequencies, wireless communication technologies such as ITS Connect, etc. The mobile communication unit 110A is realized by a communication module. The mobile communication unit 110A communicates with other devices such as the server 300 according to the communication standards of mobile phones such as LTE (Long Term Evolution) via the base station 200 and the communication network 50.

[0020] The information processing unit 104A is connected to the positioning unit 102A, the vehicle-to-vehicle communication unit 106A, and the mobile communication unit 110A. The information processing unit 104A functions as a reception unit 112A, a processing unit 114A, a creation unit 116A, and a communication control unit 118A. The reception unit 112A acquires the vehicle exchange information received by the vehicle-to-vehicle communication unit 106A and accepts the acquired vehicle exchange information. The reception unit 112A acquires the first vehicle information included in the accepted vehicle exchange information, outputs the acquired first vehicle information to the storage unit 108A, and stores it as surrounding vehicle information. Also, the reception unit 112A acquires the vehicle information registration response received by the mobile communication unit 110A and accepts the acquired vehicle information registration response. The reception unit 112A acquires the first notification information and the second notification information included in the accepted vehicle information registration response, outputs the acquired first notification information and the second notification information to the storage unit 108A, and stores them. The processing unit 114A causes the positioning unit 102A to perform positioning in the first cycle. The processing unit 114A acquires the position information that is the result of the positioning from the positioning unit 102A and the time information when the positioning unit 102A measures the position of the own vehicle 100-A. The processing unit 114A outputs the first vehicle information, which is information associating the identification information of the own vehicle 100-A, the acquired position information of the own vehicle 100-A, and the time information when the position of the own vehicle 100-A is measured, to the storage unit 108A and stores it. The creation unit 116A creates vehicle exchange information including the first vehicle information. The communication control unit 118A acquires the vehicle exchange information from the creation unit 116A and causes the vehicle-to-vehicle communication unit 106A to transmit the acquired vehicle exchange information. The creation unit 116A associates the identification information of the host vehicle 100-A stored in the storage unit 108A, the position information of the host vehicle 100-A, and the time information when the position of the host vehicle 100-A was measured to form the first vehicle information, the identification information of one or more other vehicles stored, the second vehicle information obtained by associating the time information when the positions of the one or more other vehicles were measured, and the identification information of the user who communicates using the mobile communication network, and creates a vehicle information registration request addressed to the server 300. An example of the identification information of the user who communicates using the mobile communication network is the subscriber identification number (IMSI: International Mobile Subscriber Identity). The identification information of the user is used when the vehicle 100-A connects to the mobile communication network. The communication control unit 118A acquires the vehicle information registration request from the creation unit 116A and causes the mobile communication unit 110A to transmit the acquired vehicle information registration request.

[0021] The storage unit 108A is connected to the information processing unit 104A. The storage unit 108A stores in association the identification information of the host vehicle 100-A, the position information of the host vehicle 100-A, and the time information when the position of the host vehicle 100-A was measured. Further, the storage unit 108A stores in association the identification information of one or more vehicles other than the host vehicle 100-A, the position information of the one or more vehicles other than the host vehicle 100-A, and the time information when the positions of the one or more vehicles other than the host vehicle 100-A were measured. FIG. 3 is a diagram showing an example of information stored in the in-vehicle device's storage unit. The storage unit 108A stores by associating the identification information of the vehicle, the position information of the vehicle, and the time information when the position of the vehicle was measured. In the example shown in FIG. 3, the vehicle identification information "0001", the vehicle position information "(**,**)", and the time information "++:++" when the position of the vehicle was measured are associated, the vehicle identification information "0002", the vehicle position information "(**,**)", and the time information "++:++" when the position of the vehicle was measured are associated, and the vehicle identification information "0003", the vehicle position information "(**,**)", and the time information "++:++" when the position of the vehicle was measured are associated. The storage unit 108A acquires the first vehicle information output by the processing unit 114A, and stores by associating the identification information of the host vehicle 100-A included in the acquired first vehicle information, the position information of the host vehicle 100-A, and the time information when the position of the host vehicle 100-A was measured. Thereby, the vehicle 100-A stores the latest position information of the host vehicle 100-A. In addition, the storage unit 108A acquires the first notification information output by the reception unit 112A, and stores the identification information of one or more vehicles included in the acquired first notification information, the position information of the one or more vehicles associated with the identification information of the one or more vehicles, and the time information when the positions of the one or more vehicles were measured. Thereby, the identification information of one or more vehicles that were not stored in the storage unit 108A, the position information of the one or more vehicles associated with the identification information of the one or more vehicles, and the time information when the positions of the one or more vehicles were measured can be stored by association. Further, the storage unit 108A acquires the second notification information output by the reception unit 112A, and uses the identification information of one or more vehicles other than the host vehicle 100, the position information of the one or more vehicles, and the time information when the positions of the one or more vehicles were measured included in the acquired second notification information to update the identification information of one or more vehicles other than the host vehicle 100-A stored in the storage unit 108A, the position information of the one or more vehicles, and the time information when the positions of the one or more vehicles were measured. As a result, the vehicle 100-A can update the position information of other vehicles stored in the storage unit 108A to later (newer) time information. Returning to FIG. 2, the description will continue.

[0022] The creation unit 116A acquires the identification information of the vehicles around the vehicle 100-A from the surrounding vehicle information stored in the storage unit 108A. The creation unit 116A creates a message A including the acquired identification information of the vehicles around the vehicle 100-A and a message to the vehicle 100-B (in-vehicle unit). An example of the message is a right turn request to the vehicle 100-B which is a vehicle facing forward when the vehicle 100-A is located in front of an intersection. In this case, by creating a message A including a right turn request to the vehicle 100-B, the vehicle 100-A can request the vehicle 100-B to stop. An example of the message is an overtaking request to the vehicle 100-B which is the vehicle in front when the vehicle 100-A is located on a highway. In this case, by creating a message A including an overtaking request to the vehicle 100-B, the vehicle 100-A can request the vehicle 100-B to change lanes. The communication control unit 118A acquires the message A from the creation unit 116A and causes the vehicle-to-vehicle communication unit 106A to transmit the acquired message A.

[0023] The creation unit 116A acquires the response message AR from the vehicle-to-vehicle communication unit 106A or the mobile communication unit 110A. The creation unit 116A acquires the identification information of the vehicles around vehicle 100-A from the surrounding vehicle information stored in the storage unit 108A. The creation unit 116A creates message B for the acquired response message AR. Message B includes the acquired identification information of the vehicles around vehicle 100-A and the message to in-vehicle unit of vehicle 100-B. For example, the creation unit 116A creates message B including a response to the message included in the response message AR based on the response of the person riding in vehicle 100-A. An example of the message is a formal right-turn request to vehicle 100-B, which is the oncoming vehicle in front, when vehicle 100-A is located before an intersection. An example of the message is a formal overtaking request to vehicle 100-B, which is the vehicle in front, when vehicle 100-A is located on a highway. The communication control unit 118A acquires message B from the creation unit 116A. The communication control unit 118A acquires the response message AR from the vehicle-to-vehicle communication unit 106A or the mobile communication unit 110A. The communication control unit 118A acquires the identification information of the vehicles around vehicle 100-B included in the response message AR. The communication control unit 118A acquires the identification information of the vehicles around vehicle 100-A from the storage unit 108A. Based on the acquired identification information of the vehicles around vehicle 100-B and the identification information of the vehicles around vehicle 100-A, the communication control unit 118A causes the vehicle-to-vehicle communication unit 106A or the mobile communication unit 110A to transmit the acquired message B. For example, the communication control unit 118A calculates the matching rate between the identification information of the vehicles around vehicle 100-B and the identification information of the vehicles around vehicle 100-A. Here, the matching rate is obtained by dividing the number of matches between the identification information of the vehicles around vehicle 100-B and the identification information of the vehicles around vehicle 100-A by the number of the identification information of the vehicles around vehicle 100-A. When the matching rate is equal to or higher than the threshold value, the communication control unit 118A assumes that vehicle 100-B is located in a place with a good view from vehicle 100-A. Therefore, when the matching rate is equal to or higher than the threshold value, the communication control unit 118A causes the vehicle-to-vehicle communication unit 106A to transmit a response message B. When the matching rate is less than the threshold value, the communication control unit 118A assumes that vehicle 100-B is located in a place with a poor view from vehicle 100-A. Therefore, when the matching rate is less than the threshold value, the communication control unit 118A causes the mobile communication unit 110A to transmit a message B.

[0024] All or part of the positioning unit 102A, the reception unit 112A, the processing unit 114A, the creation unit 116A, and the communication control unit 118A are, for example, functional units (hereinafter referred to as software functional units) realized by a processor such as a CPU (Central Processing Unit) executing a program stored in the storage unit 108A. Note that all or part of the positioning unit 102A, the reception unit 112A, the processing unit 114A, the creation unit 116A, and the communication control unit 118A may be realized by hardware such as an LSI (Large Scale Integration), an ASIC (Application Specific Integrated Circuit), or an FPGA (Field-Programmable Gate Array), or may be realized by a combination of a software functional unit and hardware.

[0025] (Vehicle 100-B) Vehicle 100-B is equipped with an in-vehicle unit 150B. The in-vehicle unit 150B includes a positioning unit 102B, an information processing unit 104B, an inter-vehicle communication unit 106B, a mobile communication unit 110B, and a memory unit 108B. The information processing unit 104B is connected to the positioning unit 102B, the inter-vehicle communication unit 106B, and the mobile communication unit 110B. The information processing unit 104B functions as a reception unit 112B, a processing unit 114B, a creation unit 116B, and a communication control unit 118B. Since the positioning unit 102B, the inter-vehicle communication unit 106B, the mobile communication unit 110B, the memory unit 108B, the reception unit 112B, and the processing unit 114B can respectively apply the positioning unit 102A, the inter-vehicle communication unit 106A, the mobile communication unit 110A, the memory unit 108A, the reception unit 112A, and the processing unit 114A, the description here is omitted. The inter-vehicle communication unit 106B receives message A transmitted by the in-vehicle unit 150-A. The creation unit 116B acquires message A from the inter-vehicle communication unit 106B. The creation unit 116B acquires the identification information of the vehicles around vehicle 100-B from the surrounding vehicle information stored in the memory unit 108B. The creation unit 116B creates a response message AR, which is a response to the acquired message A, including the acquired identification information of the vehicles around vehicle 100-B and a message to vehicle 100-A (its in-vehicle unit). For example, the creation unit 116B creates a response message AR including a response to the message included in message A based on the response of the person riding in vehicle 100-B. An example of the message is acceptance or rejection of the message included in message A. The communication control unit 118B acquires the response message AR from the creation unit 116B. The communication control unit 118B acquires message A from the inter-vehicle communication unit 106B. The communication control unit 118B acquires the identification information of the vehicles around vehicle 100-A included in message A. The communication control unit 118B acquires the identification information of the vehicles around vehicle 100-B from the memory unit 108B. Based on the acquired identification information of the vehicles around vehicle 100-A and the identification information of the vehicles around vehicle 100-B, the communication control unit 118B causes the inter-vehicle communication unit 106B or the mobile communication unit 110B to transmit the acquired response message A. For example, the communication control unit 118B calculates the matching rate between the identification information of the vehicles around vehicle 100-A and the identification information of the vehicles around vehicle 100-B. Here, the matching rate is obtained by dividing the number of matches between the identification information of the vehicles around vehicle 100-A and the identification information of the vehicles around vehicle 100-B by the number of the identification information of the vehicles around vehicle 100-B. When the matching rate is equal to or higher than the threshold value, the communication control unit 118B assumes that vehicle 100-A is located in a place with good visibility from vehicle 100-B. Therefore, when the matching rate is equal to or higher than the threshold value, the communication control unit 118B causes the vehicle-to-vehicle communication unit 106B to transmit response message A. When the matching rate is less than the threshold value, the communication control unit 118B assumes that vehicle 100-A is located in a place with poor visibility from vehicle 100-B. Therefore, when the matching rate is less than the threshold value, the communication control unit 118B causes the mobile communication unit 110B to transmit response message A.

[0026] The creation unit 116B acquires message B from the vehicle-to-vehicle communication unit 106B or the mobile communication unit 110B. The creation unit 116B acquires the identification information of the vehicles around vehicle 100-B from the surrounding vehicle information stored in the storage unit 108B. The creation unit 116B creates a response message BR, which is a response to the acquired message B, including the acquired identification information of the vehicles around vehicle 100-B and the message to vehicle 100-A (in-vehicle unit). For example, the creation unit 116B creates a response message BR including a response to the message included in message B based on the response of the person riding in vehicle 100-B. An example of the message is an end report for the message included in message B. The communication control unit 118B acquires the response message BR from the creation unit 116B. The communication control unit 118B acquires the message B from the vehicle-to-vehicle communication unit 106B. The communication control unit 118B acquires the identification information of the vehicles around vehicle 100-A included in the message B. The communication control unit 118B acquires the identification information of the vehicles around vehicle 100-B from the storage unit 108B. Based on the acquired identification information of the vehicles around vehicle 100-A and the identification information of the vehicles around vehicle 100-B, the communication control unit 118B causes the vehicle-to-vehicle communication unit 106B or the mobile communication unit 110B to transmit the acquired response message BR. For example, the communication control unit 118B calculates the matching rate between the identification information of the vehicles around vehicle 100-A and the identification information of the vehicles around vehicle 100-B. When the matching rate is equal to or higher than the threshold value, the communication control unit 118B causes the vehicle-to-vehicle communication unit 106B to transmit the response message BR. When the matching rate is less than the threshold value, the communication control unit 118B causes the mobile communication unit 110B to transmit the response message BR. Hereinafter, any in-vehicle unit among the in-vehicle units 150-A to 150-C is described as the in-vehicle unit 150.

[0027] All or part of the positioning unit 102B, the reception unit 112B, the processing unit 114B, the creation unit 116B, and the communication control unit 118B are, for example, functional units (hereinafter referred to as software functional units) realized by a processor such as a CPU executing a program stored in the storage unit 108B. Note that all or part of the positioning unit 102B, the reception unit 112B, the processing unit 114B, the creation unit 116B, and the communication control unit 118B may be realized by hardware such as an LSI, an ASIC, or an FPGA, or may be realized by a combination of a software functional unit and hardware.

[0028] (Server) The server 300 will be described. An example of the server 300 is a cloud server. The server 300 includes an information processing unit 304, a communication unit 306, and a storage unit 308. The communication unit 306 is implemented by a communication module. The communication unit 306 communicates with other devices such as the in-vehicle unit 150 in accordance with the communication standards of mobile phones such as LTE via the communication network 50 and the base station 200. The information processing unit 304 is connected to the communication unit 306. The information processing unit 304 functions as a reception unit 312 and a processing unit 314. The reception unit 312 acquires the vehicle information registration request received by the communication unit 306 and accepts the acquired vehicle information registration request. The processing unit 314 acquires the vehicle information registration request accepted by the reception unit 312, acquires the first vehicle information included in the acquired vehicle information registration request, and outputs the acquired first vehicle information to the storage unit 308. Further, the processing unit 314 acquires the second vehicle information included in the acquired vehicle information registration request. The processing unit 314 identifies one or more pieces of identification information of other vehicles other than the one or more pieces of identification information of other vehicles included in the acquired second vehicle information among the one or more pieces of identification information of other vehicles stored in the storage unit 308. The processing unit 314 selects one or more pieces of identification information of other vehicles identified from the stored information, one or more pieces of position information of the one or more other vehicles associated with the one or more pieces of identification information of the other vehicles, and time information when the positions of the one or more other vehicles were measured. The processing unit 314 creates first notification information associating the selected one or more pieces of identification information of other vehicles, the one or more pieces of position information of the one or more other vehicles, and the time information when the positions of the one or more other vehicles were measured. The processing unit 314 creates a vehicle information registration response addressed to the vehicle 100, including the created first notification information and second notification information, and outputs the created vehicle information registration response to the communication unit 306.

[0029] The storage unit 308 is connected to the information processing unit 304. The storage unit 308 stores in association with each other the identification information of the vehicle 100, the position information of the vehicle 100, and the time information when the position of the vehicle 100 was measured. FIG. 4 is a diagram showing an example of information stored in the storage unit of the server. The storage unit 308 stores by associating the identification information of the vehicle, the position information of the vehicle, and the time information when the position of the vehicle is measured. In the example shown in FIG. 4, the vehicle identification information "0001", the vehicle position information "(**,**)", and the time information "++:++" when the position of the vehicle is measured are associated, the vehicle identification information "0002", the vehicle position information "(**,**)", and the time information "++:++" when the position of the vehicle is measured are associated, and the vehicle identification information "0003", the vehicle position information "(**,**)", and the time information "++:++" when the position of the vehicle is measured are associated. The storage unit 308 acquires the first vehicle information output by the processing unit 314, and stores by associating the identification information of the host vehicle 100 included in the acquired first vehicle information, the position information of the host vehicle 100, and the time information when the position of the host vehicle 100 is measured. After the storage unit 308 stores by associating the position information of the host vehicle 100 and the time information when the position of the host vehicle 100 is measured, when the processing unit 314 outputs the first vehicle information, the storage unit 308 acquires the first vehicle information, and updates the position information of the host vehicle 100 and the time information when the position of the host vehicle 100 is measured that are stored in association with the identification information of the host vehicle 100 included in the acquired first vehicle information. Thereby, the storage unit 308 stores the latest position information of the vehicle 100. All or part of the reception unit 312 and the processing unit 314 are, for example, functional units (hereinafter referred to as software functional units) realized by a processor such as a CPU executing a program stored in the storage unit 308. Note that all or part of the reception unit 312 and the processing unit 314 may be realized by hardware such as an LSI, an ASIC, or an FPGA, or may be realized by a combination of a software functional unit and hardware.

[0030] (Operation of the inter-vehicle communication system) FIG. 5 and FIG. 6 are flowcharts showing an example of the operation of the vehicle-to-vehicle communication system according to the present embodiment. FIG. 7 is a diagram for explaining an example of the operation of the vehicle-to-vehicle communication system according to the present embodiment. As an example, a case where the vehicle 100-A is located in front of an intersection and requests a right turn to the vehicle 100-B, which is a vehicle traveling in the opposite direction ahead, will be described. This will be described with reference to FIG. 5. (Step S1-1) In in-vehicle unit 150-A, creation unit 116A acquires identification information of vehicles around vehicle 100-A from the surrounding vehicle information stored in storage unit 108A. Creation unit 116A creates message A including the acquired identification information of vehicles around vehicle 100-A and a message to vehicle 100-B. An example of the message is a right turn request to vehicle 100-B, which is a vehicle traveling in the opposite direction ahead, when vehicle 100-A is located in front of an intersection. (Step S2-1) In in-vehicle unit 150-A, communication control unit 118A acquires message A from creation unit 116A and causes vehicle-to-vehicle communication unit 106A to transmit the acquired message A. (Step S3-1) In in-vehicle unit 150-A, vehicle-to-vehicle communication unit 106A transmits message A to in-vehicle unit 150-B. (Step S4-1) In in-vehicle unit 150-B, vehicle-to-vehicle communication unit 106B receives message A transmitted by in-vehicle unit 150-A. (Step S5-1) In in-vehicle unit 150-B, creation unit 116B acquires message A from vehicle-to-vehicle communication unit 106B. Creation unit 116B acquires identification information of vehicles around vehicle 100-B from the surrounding vehicle information stored in storage unit 108B. Creation unit 116B creates response message A, which is a response to the acquired message A, including the acquired identification information of vehicles around vehicle 100-B and a message to vehicle 100-A (in-vehicle unit).

[0031] (Step S6-1) In in-vehicle unit 150-B, communication control unit 118B acquires response message A from creation unit 116B. Communication control unit 118B acquires message A from vehicle-to-vehicle communication unit 106B. Communication control unit 118B acquires the identification information of the vehicles around vehicle 100-A included in message A. Communication control unit 118B acquires the identification information of the vehicles around vehicle 100-B from storage unit 108B. Based on the acquired identification information of the vehicles around vehicle 100-A and the identification information of the vehicles around vehicle 100-B, communication control unit 118B calculates the matching rate between the identification information of the vehicles around vehicle 100-A and the identification information of the vehicles around vehicle 100-B. Communication control unit 118B determines whether the calculated matching rate is equal to or greater than the threshold value. (Step S7-1) In in-vehicle unit 150-B, when the matching rate is equal to or greater than the threshold value, communication control unit 118B causes vehicle-to-vehicle communication unit 106B to transmit response message A. (Step S8-1) In in-vehicle unit 150-B, vehicle-to-vehicle communication unit 106B transmits response message AR. (Step S9-1) In in-vehicle unit 150-B, when the matching rate is less than the threshold value, communication control unit 118B causes mobile communication unit 110B to transmit response message AR. (Step S10-1) In in-vehicle unit 150-B, mobile communication unit 110B transmits response message AR. (Step S11-1) In in-vehicle unit 150-A, vehicle-to-vehicle communication unit 106A or mobile communication unit 110A receives response message AR transmitted by in-vehicle unit 150-B. Continuing the explanation with reference to FIG. 6.

[0032] (Step S1-2) In in-vehicle unit 150-A, creation unit 116A acquires response message AR from vehicle-to-vehicle communication unit 106A or mobile communication unit 110A. Creation unit 116A acquires the identification information of the vehicles around vehicle 100-A from the surrounding vehicle information stored in storage unit 108A. Creation unit 116A creates message B for the acquired response message AR, which includes the acquired identification information of the vehicles around vehicle 100-A and the message to vehicle 100-B (in-vehicle unit). (Step S2-2) In in-vehicle unit 150-A, communication control unit 118A acquires message B from creation unit 116A. Communication control unit 118A acquires response message AR from vehicle-to-vehicle communication unit 106A or mobile communication unit 110A. Communication control unit 118A acquires the identification information of the vehicles around vehicle 100-B included in response message AR. Communication control unit 118A acquires the identification information of the vehicles around vehicle 100-A from storage unit 108A. Based on the acquired identification information of the vehicles around vehicle 100-B and the identification information of the vehicles around vehicle 100-A, communication control unit 118A calculates the matching rate between the identification information of the vehicles around vehicle 100-B and the identification information of the vehicles around vehicle 100-A. Communication control unit 118A determines whether the calculated matching rate is equal to or greater than a threshold value. (Step S3-2) In in-vehicle unit 150-A, when the matching rate is equal to or greater than the threshold value, communication control unit 118A causes vehicle-to-vehicle communication unit 106A to transmit message B. (Step S4-2) In in-vehicle unit 150-A, vehicle-to-vehicle communication unit 106B transmits message B. (Step S5-2) In in-vehicle unit 150-A, when the matching rate is less than the threshold value, communication control unit 118A causes mobile communication unit 110B to transmit message B. (Step S6-2) In in-vehicle unit 150-A, mobile communication unit 110A transmits message B. (Step S7-2) In in-vehicle unit 150-B, vehicle-to-vehicle communication unit 106B or mobile communication unit 110B receives message B transmitted by in-vehicle unit 150-A.

[0033] (Step S8-2) In in-vehicle unit 150-B, creation unit 116B acquires message B from vehicle-to-vehicle communication unit 106B or mobile communication unit 110B. Creation unit 116B acquires the identification information of the vehicles around vehicle 100-B from the surrounding vehicle information stored in storage unit 108B. Creation unit 116B creates response message BR, which is a response to the acquired message B and includes the acquired identification information of the vehicles around vehicle 100-B and the message to vehicle 100-A (in-vehicle unit). (Step S9-2) In in-vehicle unit 150-B, communication control unit 118B acquires response message BR from creation unit 116B. Communication control unit 118B acquires message B from vehicle-to-vehicle communication unit 106B or mobile communication unit 110B. Communication control unit 118B acquires the identification information of the vehicles around vehicle 100-A included in message B. Communication control unit 118B acquires the identification information of the vehicles around vehicle 100-B from storage unit 108B. Based on the acquired identification information of the vehicles around vehicle 100-A and the identification information of the vehicles around vehicle 100-B, communication control unit 118B calculates the matching rate between the identification information of the vehicles around vehicle 100-A and the identification information of the vehicles around vehicle 100-B. Communication control unit 118B determines whether the calculated matching rate is equal to or greater than the threshold value. (Step S10-2) In in-vehicle unit 150-B, when the matching rate is equal to or greater than the threshold value, communication control unit 118B causes vehicle-to-vehicle communication unit 106B to transmit response message BR. (Step S11-2) In in-vehicle unit 150-B, vehicle-to-vehicle communication unit 106B transmits response message BR. (Step S12-2) In in-vehicle unit 150-B, when the matching rate is less than the threshold value, communication control unit 118B causes mobile communication unit 110B to transmit response message BR. (Step S13-2) In in-vehicle unit 150-B, mobile communication unit 110B transmits response message BR. (Step S14-2) In in-vehicle unit 150-A, vehicle-to-vehicle communication unit 106A or mobile communication unit 110A receives response message BR transmitted by in-vehicle unit 150-B.

[0034] In the above-described embodiment, the case where vehicle-to-vehicle communication system 1 includes vehicle 100-A, vehicle 100-B, and vehicle 100-C has been described, but it is not limited to this example. For example, vehicle-to-vehicle communication system 1 may be configured to include one to two vehicles, or may be configured to include four or more vehicles. In the above-described embodiment, the case where the vehicle-to-vehicle communication system 1 includes one base station 200 has been described, but the present invention is not limited to this example. For example, the vehicle-to-vehicle communication system 1 may be provided with two or more base stations. In this case, each of the plurality of base stations is connected to the server 300 via the communication network 50. In the above-described embodiment, the in-vehicle device 150-A may create a message B including the surrounding vehicle information of the vehicle 100-A instead of the identification information of the surrounding vehicles of the vehicle 100-A. The in-vehicle device 150-B may create a response message AR including the surrounding vehicle information of the vehicle 100-B and the message B instead of the identification information of the surrounding vehicles of the vehicle 100-B. In the above-described embodiment, the in-vehicle device 150-A may further have the function of the in-vehicle device 150-B, or the in-vehicle device 150-B may further have the function of the in-vehicle device 150-A.

[0035] According to the vehicle-to-vehicle communication system of the present embodiment, the vehicle-to-vehicle communication system includes an in-vehicle device 150-A as a first in-vehicle device mounted on a vehicle 100-A as a first vehicle and an in-vehicle device 150-B as a second in-vehicle device mounted on a vehicle 100-B as a second vehicle. The in-vehicle device 150-A includes an inter-vehicle communication unit 106A as a first inter-vehicle communication unit that communicates with the vehicle, a mobile communication unit 110A as a first mobile communication unit that communicates using the mobile communication network, a creation unit 116A as a first creation unit that creates a message A as a first message including a message to the vehicle 100-A, and a communication control unit 118A as a first communication control unit that causes the inter-vehicle communication unit 106A to transmit the first message created by the creation unit. The in-vehicle device 150-B includes an inter-vehicle communication unit 106B as a second vehicle-to-vehicle communication unit that communicates with a vehicle, a mobile communication unit 110B as a second mobile communication unit that communicates using a mobile communication network, a creation unit 116B as a second creation unit that creates a response message AR as a first response message to message A received by the inter-vehicle communication unit 106B, and based on the identification information of the vehicles around vehicle 100-A included in message A and the identification information of the vehicles around vehicle 100-B, a communication control unit 118B as a second communication control unit that causes the inter-vehicle communication unit 106B or the mobile communication unit 110B to transmit the response message AR created by the creation unit 116B. By configuring in this way, the in-vehicle device 150-B can cause the inter-vehicle communication unit 106B or the mobile communication unit 110B to transmit the response message AR created by the creation unit 116B based on the identification information of the vehicles around vehicle 100-A included in message A and the identification information of the vehicles around vehicle 100-B, so that more efficient communication between vehicles can be realized. In conventional V2V communication, it is basically one-to-many broadcast communication and no reach confirmation is performed, but reach confirmation can be performed.

[0036] In the vehicle-to-vehicle communication system 1, the creation unit 116A creates a message B as a second message including a message to vehicle 100-B for the response message AR, and the communication control unit 118A causes the inter-vehicle communication unit 106A or the mobile communication unit 110A to transmit the message B created by the creation unit 116A based on the identification information of the vehicles around vehicle 100-B included in the response message AR and the identification information of the vehicles around vehicle 100-A. The creation unit 116B creates a response message BR as a second response message to message B, and the communication control unit 118B causes the vehicle-to-vehicle communication unit 106B or the mobile communication unit 110B to transmit the response message BR created by the creation unit 116B based on the identification information of the vehicles around vehicle 100-A included in message B and the identification information of the vehicles around vehicle 100-B. By configuring in this way, in-vehicle unit 150-A can cause the vehicle-to-vehicle communication unit 106A or the mobile communication unit 110A to transmit message B created by the creation unit 116A based on the identification information of the vehicles around vehicle 100-B included in the response message AR and the identification information of the vehicles around vehicle 100-A. In-vehicle unit 150-B can cause the vehicle-to-vehicle communication unit 106B or the mobile communication unit 110B to transmit the response message BR created by the creation unit 116B based on the identification information of the vehicles around vehicle 100-A included in message B and the identification information of the vehicles around vehicle 100-B. Therefore, more efficient communication between vehicles can be realized.

[0037] In the vehicle-to-vehicle communication system 1, the in-vehicle unit 150-A further includes a processing unit 114A as a first processing unit that acquires the identification information of other vehicles, the position information of other vehicles, and the time information when the position information was measured, which are included in the position exchange information received by the vehicle-to-vehicle communication unit 106A, and stores the peripheral vehicle information in which the acquired identification information of other vehicles, the position information of other vehicles, and the time information when the position information was measured are associated, in the 108A as a first storage unit. The creation unit 116A creates the identification information of the vehicles around the first vehicle including the identification information of one or more other vehicles included in the peripheral vehicle information stored in the storage unit 108A, and creates a message A including the created identification information of the vehicles around the first vehicle. The in-vehicle unit 150-B obtains the identification information of other vehicles, the position information of other vehicles, and the time information when the position information was measured, which are included in the position exchange information received by the vehicle-to-vehicle communication unit 106B, and stores the peripheral vehicle information in which the obtained identification information of other vehicles, the position information of other vehicles, and the time information when the position information was measured are associated, in the storage unit 108B as the second storage unit, and further includes a processing unit 114B as the second processing unit. The communication control unit 118B causes the vehicle-to-vehicle communication unit 106B or the mobile communication unit 110B to transmit the response message AR created by the creation unit 116B to the vehicle 100-A, based on the identification information of the vehicles around the vehicle 100-A included in the message A and the identification information of the vehicles around the vehicle 100-B included in the peripheral vehicle information stored in the storage unit 108B. By configuring in this way, in the in-vehicle unit 150-A, the amount of information included in the message A can be reduced compared to the case where the creation unit 116A transmits the message A including the first vehicle information.

[0038] In the vehicle-to-vehicle communication system 1, the processing unit 114A updates the peripheral vehicle information stored in the storage unit 108A based on the time information when the position information was measured. The processing unit 114B updates the peripheral vehicle information stored in the storage unit 108B based on the time information when the position information was measured. By configuring in this way, the first vehicle information included in the storage unit 108A and the first vehicle information included in the storage unit 108B can be maintained as the latest information. In the vehicle-to-vehicle communication system 1, the communication control unit 118B causes the vehicle-to-vehicle communication unit 106B to transmit the response message AR when the matching rate between the identification information of the vehicles around the first vehicle and the identification information of the vehicles around the second vehicle is equal to or higher than the threshold, based on the identification information of the vehicles around the first vehicle and the identification information of the vehicles around the second vehicle, and causes the mobile communication unit 110B to transmit the response message AR when the matching rate is less than the threshold. By configuring in this way, vehicle-to-vehicle communication and mobile communication can be properly used based on the identification information of the vehicles around the first vehicle and the identification information of the vehicles around the second vehicle, so that more efficient communication between vehicles can be realized. In the vehicle-to-vehicle communication system 1, the communication control unit 118B changes the threshold value based on the number of pieces of identification information of vehicles around vehicle 100-B. By configuring it in this way, since the threshold value can be changed based on the number of pieces of identification information of vehicles around vehicle 100-B, vehicle-to-vehicle communication and mobile communication can be used appropriately according to the actual situation rather than when the threshold value is constant. According to the vehicle-to-vehicle communication system, in-vehicle device, communication method, and program of the embodiment, it is assumed that traffic safety will be improved and all people will be able to use a safe, affordable, easy-to-use, and sustainable transportation system. Therefore, it becomes possible to contribute to Goal 11, "Sustainable cities and communities," of the Sustainable Development Goals (SDGs) led by the United Nations.

[0039] As described above, the embodiments have been explained, but these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, changes, and combinations can be made without departing from the gist of the invention. These embodiments are included in the scope and gist of the invention and are also included in the invention described in the claims and its equivalent scope. Note that the in-vehicle device 150 included in the vehicle-to-vehicle communication system 1 described above and the server 300 may be realized by a computer. In that case, a program for realizing the functions of each functional block is recorded on a computer-readable recording medium. The program recorded on this recording medium may be read into a computer system and realized by the CPU executing it. Here, the "computer system" is assumed to include hardware such as an OS (Operating System) and peripheral devices. Also, the "computer-readable recording medium" refers to portable media such as flexible disks, magneto-optical disks, ROMs, CD-ROMs, etc. Further, the "computer-readable recording medium" includes storage devices such as hard disks built into computer systems. Additionally, the "computer-readable recording medium" may include those that dynamically hold programs for a short period of time. Those that dynamically hold programs for a short period of time are, for example, communication lines when transmitting programs via networks such as the Internet or communication lines such as telephone lines. Also, the "computer-readable recording medium" may include those that hold programs for a certain period of time, such as volatile memories inside computer systems that serve as servers or clients. Also, the above program may be for realizing a part of the functions described above. Also, the above program may be realizable in combination with a program already recorded in the computer system for realizing the functions described above. Also, the above program may be realized using a programmable logic device. The programmable logic device is, for example, an FPGA (Field Programmable Gate Array).

Explanation of Signs

[0040] 1…Vehicle-to-vehicle communication system, 50…Communication network, 100-A, 100-B, 100-C…Vehicles, 102A, 102B…Positioning units, 104A, 104B…Information processing units, 106A, 106B…Vehicle-to-vehicle communication units, 108A, 108B…Storage units, 112A, 112B…Reception units, 114A,114B…Processing units, 116A, 116B…Creation units, 118A,118B…Communication control units, 110A, 110B…Mobile communication units, 200…Base station, 300…Server, 304…Information processing unit, 306…Communication unit, 308…Storage unit, 312…Reception unit, 314…Processing unit

Claims

1. A vehicle-to-vehicle communication system including a first in-vehicle device mounted on a first vehicle and a second in-vehicle device mounted on a second vehicle, wherein the first in-vehicle device includes: a first vehicle-to-vehicle communication unit for communicating with a vehicle; a first mobile communication unit for communicating using a mobile communication network; a first creation unit for creating a first message including a message to the second vehicle; a first communication control unit for causing the first vehicle-to-vehicle communication unit to transmit the first message created by the first creation unit, and the second in-vehicle device includes: a second vehicle-to-vehicle communication unit for communicating with a vehicle; a second mobile communication unit for communicating using a mobile communication network; a second creation unit for creating a first response message for the first message received by the second vehicle-to-vehicle communication unit; a second communication control unit for selecting the second vehicle-to-vehicle communication unit or the second mobile communication unit based on the identification information of the vehicles around the first vehicle included in the first message and the identification information of the vehicles around the second vehicle, and causing the second vehicle-to-vehicle communication unit or the second mobile communication unit to transmit the first response message created by the second creation unit, and is a vehicle-to-vehicle communication system.

2. The vehicle-to-vehicle communication system according to claim 1, wherein the second communication control unit selects the second vehicle-to-vehicle communication unit or the second mobile communication unit based on a comparison result between the identification information of the vehicles around the first vehicle and the identification information of the vehicles around the second vehicle.

3. The first creation unit creates a second message including a message to the second vehicle for the first response message, the first communication control unit causes the first vehicle-to-vehicle communication unit or the first mobile communication unit to transmit the second message created by the first creation unit based on the identification information of the vehicles around the second vehicle included in the first response message and the identification information of the vehicles around the first vehicle, the second creation unit creates a second response message for the second message, and the second communication control unit causes the second vehicle-to-vehicle communication unit or the second mobile communication unit to transmit the second response message created by the second creation unit based on the identification information of the vehicles around the first vehicle included in the second message and the identification information of the vehicles around the second vehicle, according to claim 1 or claim 2.

4. The first in-vehicle device, The first processing unit acquires the identification information of other vehicles, the position information of other vehicles, and the time information when the position information was measured, which are included in the position exchange information received by the first vehicle-to-vehicle communication unit, and stores the peripheral vehicle information, in which the acquired identification information of other vehicles, the position information of other vehicles, and the time information when the position information was measured are associated, in the first storage unit. further comprising The first creation unit creates the identification information of the vehicles around the first vehicle including the identification information of one or more other vehicles included in the peripheral vehicle information stored in the first storage unit, and creates a first message including the identification information of the vehicles around the first vehicle thus created. The second in-vehicle device The second processing unit acquires the identification information of other vehicles, the position information of other vehicles, and the time information when the position information was measured, which are included in the position exchange information received by the second vehicle-to-vehicle communication unit, and stores the peripheral vehicle information, in which the acquired identification information of other vehicles, the position information of other vehicles, and the time information when the position information was measured are associated, in the second storage unit. further comprising The second communication control unit causes the second vehicle-to-vehicle communication unit or the second mobile communication unit to transmit the first response message created by the second creation unit to the first vehicle, based on the identification information of the vehicles around the first vehicle included in the first message and the identification information of the vehicles around the second vehicle included in the peripheral vehicle information stored in the second storage unit. The vehicle-to-vehicle communication system according to any one of claims 1 to 3.

5. The first processing unit updates the peripheral vehicle information stored in the first storage unit based on the time information when the position information was measured. The second processing unit updates the peripheral vehicle information stored in the second storage unit based on the time information when the position information was measured. The vehicle-to-vehicle communication system according to claim 4.

6. The second communication control unit causes the second vehicle-to-vehicle communication unit to transmit the first response message when the matching rate between the identification information of the vehicles around the first vehicle and the identification information of the vehicles around the second vehicle is equal to or higher than a threshold, based on the identification information of the vehicles around the first vehicle and the identification information of the vehicles around the second vehicle, and causes the second mobile communication unit to transmit the first response message when the matching rate is less than the threshold. The vehicle-to-vehicle communication system according to any one of claims 1 to 5.

7. The vehicle-to-vehicle communication system according to claim 6, wherein the second communication control unit changes the threshold value based on the number of pieces of identification information of vehicles around the second vehicle.

8. An in-vehicle device mounted on a vehicle, comprising: a vehicle-to-vehicle communication unit that communicates with a vehicle; a mobile communication unit that communicates using a mobile communication network; a creation unit that creates a response message for a message transmitted by another in-vehicle device mounted on another vehicle received by the vehicle-to-vehicle communication unit; a communication control unit that selects the vehicle-to-vehicle communication unit or the mobile communication unit based on the identification information of vehicles around the other vehicle included in the message and the identification information of vehicles around the vehicle, and causes the response message created by the creation unit to be transmitted An in-vehicle device.

9. A communication method executed by a vehicle-to-vehicle communication system including a first in-vehicle device mounted on a first vehicle and a second in-vehicle device mounted on a second vehicle, wherein: the first in-vehicle device includes: a first vehicle-to-vehicle communication unit that communicates with a vehicle; a first mobile communication unit that communicates using a mobile communication network; and the second in-vehicle device includes: a second vehicle-to-vehicle communication unit that communicates with a vehicle; a second mobile communication unit that communicates using a mobile communication network; and the communication method includes: a step in which the first in-vehicle device creates a first message including a message to the second vehicle; a step in which the first in-vehicle device causes the first vehicle-to-vehicle communication unit to transmit the first message; a step in which the second in-vehicle device creates a first response message for the first message received by the second vehicle-to-vehicle communication unit; a step in which the second in-vehicle device selects the second vehicle-to-vehicle communication unit or the second mobile communication unit based on the identification information of vehicles around the first vehicle included in the first message and the identification information of vehicles around the second vehicle, and causes the first response message to be transmitted A communication method.

10. A communication method executed by an in-vehicle device mounted on a vehicle, wherein: the in-vehicle device includes: a vehicle-to-vehicle communication unit that communicates with a vehicle; a mobile communication unit that communicates using a mobile communication network; and the communication method includes: a step in which a response message for a message transmitted by another in-vehicle device mounted on another vehicle received by the vehicle-to-vehicle communication unit is created; Based on the identification information of the vehicles around the other vehicle included in the message and the identification information of the vehicles around the vehicle, select the vehicle-to-vehicle communication unit or the mobile communication unit, and cause the response message created in the step of creating to be transmitted A communication method having the above.

11. A vehicle-to-vehicle communication unit that communicates with a vehicle A mobile communication unit that communicates using a mobile communication network In a computer of an in-vehicle device including The step of creating a response message for a message transmitted by another in-vehicle device mounted on another vehicle received by the vehicle-to-vehicle communication unit Based on the identification information of the vehicles around the other vehicle included in the message and the identification information of the vehicles around the vehicle, select the vehicle-to-vehicle communication unit or the mobile communication unit, and cause the response message created in the step of creating to be transmitted A program for causing the above to be executed.

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