Communication device, communication system, control circuit, storage medium, and communication method

Abstract

The present invention addresses the problem of providing a communication device (101) that is mounted on a vehicle and can share free space information indicating places where no vehicles or obstacles exist with communication devices mounted on other vehicles. This communication device (101) is provided with: a free space information sharing unit (103) that collects self-location information and other-object location information including location information of other vehicles and obstacles, and generates host vehicle free space information indicating a place where a vehicle (1), other vehicles, or obstacles do not exist; and a wireless communication unit (104) that receives other-vehicle free space information generated by other vehicles, and transmits the host vehicle free space information to other vehicles.

Description

COMMUNICATION DEVICE, COMMUNICATION SYSTEM, CONTROL CIRCUIT, STORAGE MEDIUM, AND COMMUNICATION METHOD

[0001] The present disclosure relates to a communication device, a communication system, a control circuit, a storage medium, and a communication method that are mounted on a vehicle.

[0002] In automated driving systems, safe driving assistance systems, and the like, it is necessary to share vehicle position information, vehicle speed information, and the like between vehicles in real time. In recent years, with the spread of ITS (Intelligent Transportation Systems), technological developments have been underway to share vehicle position information, vehicle speed information, and the like between vehicles through wireless communication between vehicles. Representative wireless communication systems include DSRC (Dedicated Short-Range Communications) and C-V2X (Cellular-Vehicle-to-Everything). For example, Patent Document 1 discloses a technology in which a communication device mounted on a vehicle periodically broadcasts vehicle position information, etc. to surrounding vehicles, thereby sharing position information, etc. with surrounding vehicles. Patent Document 1 describes that DSRC can be used for communication between vehicles.

[0003] JP 2009-278194 A

[0004] However, according to the above-described conventional technology, the vehicle position information shared between vehicles indicates an area where the vehicle and other vehicles are present, but does not positively indicate that other vehicles are not present in an area where the vehicle and other vehicles are not present. In other words, in an area where the vehicle position information does not explicitly indicate the presence of other vehicles, it is unclear whether other vehicles are truly absent or whether other vehicles are actually present. Therefore, there is a problem in that vehicles equipped with communication devices cannot actively use the shared position information to change lanes into areas where other vehicles are not present, enter intersections, etc. For vehicles planning to change lanes, enter intersections, etc., free space information indicating that a certain area is free of vehicles or obstacles, i.e., a location where no vehicles or obstacles are present, is important.

[0005] The present disclosure has been made in consideration of the above, and aims to obtain a communication device that is mounted on a vehicle and can share free space information indicating locations where no vehicles or obstacles exist with communication devices mounted on other vehicles.

[0006] In order to solve the above-mentioned problems and achieve the object, the present disclosure provides a communication device mounted on a vehicle. The communication device is characterized by including: a free space information sharing unit that collects self-location information, which is vehicle location information of the vehicle, and other-vehicle location information, which includes vehicle location information of other vehicles and location information of obstacles, and generates self-vehicle free space information, which is free space information indicating locations where the vehicle, other vehicles, or obstacles are not present; and a communication unit that receives other-vehicle free space information, which is free space information generated by other vehicles, and transmits the self-vehicle free space information to the other vehicles.

[0007] The communication device of the present disclosure has the advantage that it is mounted on a vehicle and can share free space information indicating locations where no vehicles or obstacles exist with communication devices mounted on other vehicles.

[0008] FIG. 1 is a diagram showing an example of the configuration of a communication system according to the first embodiment. FIG. 1 is a diagram showing an example of the configuration of a free space information sharing unit provided in a communication device according to the first embodiment. FIG. 1 is a diagram showing an example of the configuration of a free space information generating unit provided in a communication device according to the first embodiment. FIG. 2 is a diagram showing an example of information indicated in free space information handled in a vehicle according to the first embodiment. 1 is a sequence diagram showing the operation when a vehicle that desires pace information acts as a starting point to actively search for the capabilities of surrounding vehicles; FIG. 2 is a sequence diagram showing the operation when a plurality of vehicles transmit response messages when a vehicle that desires free space information acts as a starting point to actively search for the capabilities of surrounding vehicles in a vehicle according to a sixth embodiment; FIG. 3 is a sequence diagram showing the operation when a plurality of vehicles transmit response messages when a vehicle that desires free space information acts as a starting point to actively search for the capabilities of surrounding vehicles in a vehicle according to a seventh embodiment;1 is a sequence diagram showing an operation when Model A Discovery in ProSe Direct Discovery is used for discovery. FIG. 2 is a sequence diagram showing an operation when a vehicle according to a twelfth embodiment uses a C-V2X communication unit as a wireless communication unit and uses Model B Discovery in ProSe Direct Discovery for discovery. FIG. 3 is a sequence diagram showing an operation when a vehicle according to a thirteenth embodiment uses a C-V2X communication unit as a wireless communication unit and uses Model A Discovery in Group Member Discovery for discovery. FIG. 4 is a sequence diagram showing an operation when a vehicle according to a thirteenth embodiment uses a C-V2X communication unit as a wireless communication unit and uses Model B Discovery in Group Member Discovery for discovery. 1 is a sequence diagram showing an operation when Discovery is used in a vehicle according to embodiment 14; 2 is a sequence diagram showing an operation when communication between a vehicle that desires free space information and a vehicle that provides free space information is multi-hop; 3 is a sequence diagram showing an operation when a relay vehicle is selected in a vehicle according to embodiment 14; 4 is a sequence diagram showing an operation when a relay vehicle is actively selected in a vehicle according to embodiment 15; and 5 is a sequence diagram showing an operation when a vehicle according to embodiment 16 uses ProSe UE-to-UE Relay Model A Discovery in selecting a relay vehicle. A sequence diagram showing the operation when a relay vehicle is actively selected using Discovery. A diagram showing an example of when a conflict occurs in free space information shared by multiple vehicles according to embodiment 18. A diagram showing an example of the result when a vehicle according to embodiment 18 combines multiple pieces of free space information. A first sequence diagram showing the operation when a vehicle that will quickly provide new free space information is selected when a conflict occurs when sharing free space information in a vehicle according to embodiment 19. When a conflict occurs when sharing free space information in a vehicle according to embodiment 19,A second sequence diagram showing the operation when selecting a vehicle that is to be provided with new free space information quickly. A sequence diagram showing the operation when passively selecting a vehicle that is to be provided with new free space information quickly when a conflict occurs when sharing free space information in a vehicle according to embodiment 21. A sequence diagram showing the operation when using a C-V2X communication unit when setting a primary response vehicle, secondary response vehicle, etc. when a conflict occurs when sharing free space information in a vehicle according to embodiment 22. A sequence diagram showing the operation when a vehicle according to embodiment 23 shares free space information with a vehicle that does not have absolute position information or relative position information of its own vehicle, and a surrounding vehicle estimates the absolute position information or relative position information of the vehicle. In a vehicle according to embodiment 24, a vehicle capable of positioning voluntarily performs positioning to detect a vehicle that wishes to obtain free space information. 26 is a sequence diagram showing the operation when a vehicle sharing free space information does not have absolute position information or relative position information of its own vehicle, and a surrounding vehicle estimates absolute position information or relative position information of the vehicle and actively shares the free space information; 27 is a sequence diagram showing the operation when a vehicle wishing to acquire free space information actively performs discovery, and a surrounding vehicle passively estimates absolute position information or relative position information of a vehicle that does not have absolute position information or relative position information of its own vehicle; 28 is a vehicle sharing free space information, does not have absolute position information or relative position information of its own vehicle, and a surrounding vehicle uses Ranging / SL to acquire the absolute position information or relative position information of the vehicle A sequence diagram showing the operation when estimating by Ranging / SL Positioning. In a vehicle according to the twenty-ninth embodiment, when a vehicle sharing free space information does not have absolute position information or relative position information of its own vehicle and a surrounding vehicle estimates the absolute position information or relative position information of the vehicle by Ranging / SL Positioning,31 is a sequence diagram showing the operation when actively discovering a vehicle performing ranging / SL positioning; FIG. 32 is a diagram showing an example of a case where information such as vehicle speed, vehicle movement direction, and time is included in free space information in a vehicle according to embodiment 32;

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A communication device, a communication system, a control circuit, a storage medium, and a communication method according to embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings.

[0010] First Embodiment. Fig. 1 is a diagram showing an example of the configuration of a communication system 70 according to a first embodiment. The communication system 70 includes a vehicle 1 and a vehicle 2. The communication system 70 is a system in which free space information indicating locations where no vehicles or obstacles exist is shared between the vehicle 1 and the vehicle 2. The free space information can also be said to be information indicating an empty space where no vehicles or obstacles exist. The vehicle 1 includes an application execution unit 100 and a communication device 101. The communication device 101 mounted in the vehicle 1 includes a free space information sharing unit 103 and a wireless communication unit 104. The vehicle 2 includes an application execution unit 200 and a communication device 201. The communication device 201 mounted in the vehicle 2 includes a free space information sharing unit 203 and a wireless communication unit 204.

[0011] In the following description, vehicle 1 will be referred to as the first vehicle, vehicle 2 will be referred to as the second vehicle, communication device 101 will be referred to as the first communication device, communication device 201 will be referred to as the second communication device, free space information generated by communication device 101 of vehicle 1 will be referred to as the first free space information, and free space information generated by communication device 201 of vehicle 2 will be referred to as the second free space information. Furthermore, free space information sharing unit 103 will be referred to as the first free space information sharing unit, free space information sharing unit 203 will be referred to as the second free space information sharing unit, wireless communication unit 104 will be referred to as the first communication unit, and wireless communication unit 204 will be referred to as the second communication unit. Furthermore, when vehicle 1 and communication device 101 are used as references, vehicle 1 will be simply referred to as the vehicle, vehicle 2 will be referred to as the other vehicle, the first free space information will be referred to as host vehicle free space information, and the second free space information will be referred to as other vehicle free space information.

[0012] The application execution unit 100 and the application execution unit 200 execute applications such as automated driving and safe driving support systems in each vehicle. Note that the applications executed by the application execution unit 100 and the application execution unit 200 are not limited to these. Furthermore, the number of applications simultaneously executed by the application execution unit 100 and the application execution unit 200 is not limited to one, and multiple applications may be executed simultaneously.

[0013] The communication device 101 and the communication device 201 are communication devices installed in each vehicle for sharing free space information. The communication device 101 is connected to the application execution unit 100 via an interface 102. The communication device 201 is connected to the application execution unit 200 via an interface 202. In the communication device 101, the free space information sharing unit 103 and the wireless communication unit 104 are connected via an interface 105. In the communication device 201, the free space information sharing unit 203 and the wireless communication unit 204 are connected via an interface 205. The wireless communication unit 104 and the wireless communication unit 204 are connected via an interface 900.

[0014] The wireless communication unit 104 and the wireless communication unit 204 are communication units that perform wireless communication between vehicles. The wireless communication method between the wireless communication unit 104 and the wireless communication unit 204 is not particularly limited as long as it is a wireless communication method that allows wireless communication between vehicles.

[0015] Next, an operation will be described when the communication device 101 transmits free space information of vehicle 1, which is the subject vehicle, to the communication device 201 of vehicle 2, which is another vehicle. Controlled by the application execution unit 100 via the interface 102, the free space information sharing unit 103 generates and analyzes free space information and transmits the free space information to the wireless communication unit 104 via the interface 105. The wireless communication unit 104 transmits the free space information to the wireless communication unit 204 via the interface 900. The wireless communication unit 204 transmits the free space information to the free space information sharing unit 203 via the interface 205. The free space information sharing unit 203 provides the free space information to the application execution unit 200 via the interface 202.

[0016] Next, the detailed configuration and operation of the free space information sharing unit 103 will be described. The free space information sharing unit 103 and the free space information sharing unit 203 have the same configuration and perform the same operation, so the following description will use the free space information sharing unit 103 as an example. Figure 2 is a diagram showing an example configuration of the free space information sharing unit 103 included in the communication device 101 according to embodiment 1. The free space information sharing unit 103 includes a free space information generation unit 130 and a free space information analysis unit 131. The free space information generation unit 130 and the free space information analysis unit 131 are connected via an interface 132, the free space information analysis unit 131 and the wireless communication unit 104 are connected via an interface 105, and the free space information analysis unit 131 and the application execution unit 100 are connected via the interface 102.

[0017] Next, the operation of the free space information sharing unit 103 will be described. The free space information generating unit 130 collects vehicle position information of the host vehicle, which is vehicle 1 equipped with the communication device 101, which is the host communication device, and vehicle position information of other vehicles. The other vehicle is, for example, vehicle 2 equipped with the communication device 201, which is another communication device, but may also be a vehicle not shown in FIG. 1. The other vehicle may also be a vehicle that does not have a communication device such as the communication devices 101 and 201 shown in FIG. 1. In the following description, the vehicle position information of the host vehicle will be referred to as self-position information, and the vehicle position information of the other vehicle will be referred to as other-vehicle position information. The other-vehicle position information may include obstacles other than the host vehicle and the other vehicle. In other words, the other-vehicle position information may include the vehicle position information of the other vehicle as well as the position information of the obstacle. Note that the term "vehicle" refers only to vehicles equipped with communication devices such as the communication devices 101 and 201 shown in FIG. 1, and vehicles that do not have communication devices such as the communication devices 101 and 201 shown in FIG. 1 may be treated in the same way as the obstacles described above. The free space information generation unit 130 uses the collected self-position information and other person's position information to generate free space information indicating locations where no vehicles or obstacles exist, and outputs the information to the free space information analysis unit 131 via the interface 132. The vehicles that are the subject of the free space information are the aforementioned self-vehicle and other vehicles. Details of the operation of the free space information generation unit 130 to generate free space information from the self-position information and other person's position information will be described later.

[0018] The free space information analysis unit 131 analyzes the free space information acquired from the free space information generation unit 130. For example, since the free space information analysis unit 131 can acquire free space information from other vehicles as described below, the free space information analysis unit 131 performs processing such as resolving conflicts between pieces of free space information, expanding the coverage range of the free space information, and merging multiple pieces of free space information using the free space information acquired from the vehicle itself and the free space information acquired from the other vehicles. In a situation where the free space information analysis unit 131 does not acquire free space information from other vehicles but acquires free space information only from the free space information generation unit 130, the free space information analysis unit 131 may analyze the free space information using the current and past several pieces of free space information acquired from the free space information generation unit 130. For example, the free space information analysis unit 131 may estimate the traveling speed of other vehicles when the traveling conditions of surrounding vehicles can be grasped from the current and past several pieces of free space information, or may treat a detection value detected only from the free space information at a certain point in time as a false detection. As will be described later, in subsequent embodiments, the free space information analysis unit 131, or a free space information analysis unit provided in another communication device, will perform analysis such as processing to resolve conflicts between free space information.

[0019] The free space information analysis unit 131 outputs the free space information to the wireless communication unit 104 via the interface 105. The wireless communication unit 104 transmits the free space information acquired from the free space information analysis unit 131 to the vehicle 2 via the interface 900. The free space information analysis unit 131 also outputs the free space information to the application execution unit 100 via the interface 102. The application execution unit 100 executes an application using the free space information acquired from the free space information analysis unit 131.

[0020] Meanwhile, in vehicle 1, the wireless communication unit 104 receives free space information transmitted from other vehicles and outputs it to the free space information analysis unit 131 via the interface 105. The free space information analysis unit 131 analyzes both the free space information obtained by the vehicle itself and the free space information obtained from other vehicles. The free space information analysis unit 131 provides the free space information obtained as a result of the analysis to the wireless communication unit 104 and the application execution unit 100.

[0021] Next, a detailed description will be given of the configuration and operation of the free space information generating unit 130. Fig. 3 is a diagram showing an example of the configuration of the free space information generating unit 130 provided in the communication device 101 according to embodiment 1. The free space information generating unit 130 includes a self-location information collecting unit 133 and an other person's location information collecting unit 134.

[0022] The self-location information collection unit 133 is a device for acquiring absolute position information or relative position information of the vehicle itself. The self-location information collection unit 133 is a self-location estimation device that utilizes, for example, a Global Navigation Satellite System (GNSS) such as a Global Positioning System (GPS), radar, a Light Detection and Ranging (LiDAR), a camera, an infrared sensor, an odometer, or the like.

[0023] The other vehicle's position information collection unit 134 is a device for acquiring absolute position information or relative position information of other vehicles. The other vehicle's position information collection unit 134 is, for example, a other vehicle's position estimation device that utilizes radar, LiDAR, a camera, an infrared sensor, or the like mounted on the vehicle 1. Note that, as described above, the other vehicles targeted by the other vehicle's position information collection unit 134 also include obstacles other than vehicles.

[0024] Next, details of the free space information handled in this embodiment will be described. The free space information in this embodiment is information for indicating a location where no vehicles or obstacles exist. FIG. 4 is a diagram showing an example of information indicated by the free space information handled by vehicles 1 and 2 according to embodiment 1. In FIG. 4, the free space information 1300 is expressed as a two-dimensional area map centered on the vehicle's position 1301. The free space information 1300 is composed of three information elements: a free space 1302, an object presence space 1303, and an uncertain space 1304. The free space 1302 is based on information obtained by some means and is an information element indicating that no object exists at that location. The object presence space 1303 is based on information obtained by some means and is an information element indicating that an object exists at that location. The uncertain space 1304 is an information element indicating that it is not possible to determine the presence of an object at that location. Examples of information obtained by some means include, but are not limited to, detection values ​​from the aforementioned radar, LiDAR, camera, infrared sensor, etc.

[0025] The free space information generation unit 130 identifies the position 1301 of the vehicle itself in the free space information 1300 from the information obtained by the self-position information collection unit 133, and determines from the information obtained by the other person's position information collection unit 134 whether the area surrounding the position 1301 of the vehicle itself is a free space 1302, an object presence space 1303, or an uncertain space 1304. For example, based on the detection results of radar, LiDAR, a camera, an infrared sensor, etc. collected by the other person's position information collection unit 134, the free space information generation unit 130 determines an area where it is determined that no vehicle or obstacle exists as a free space 1302, an area where it is determined that a vehicle or obstacle exists as an object presence space 1303, and an area where it is not possible to determine whether a vehicle or obstacle exists as an uncertain space 1304. An area where it is not possible to determine whether a vehicle or obstacle exists is, for example, an area where detection values ​​from radar, LiDAR, camera, infrared sensor, etc., i.e., other person's position information, cannot be collected due to the influence of other vehicles or obstacles, or an area where detection values ​​from radar, LiDAR, camera, infrared sensor, etc., i.e., other person's position information, are present but the values ​​do not clearly indicate the presence of a vehicle or obstacle. In this way, the free space information generation unit 130 can generate free space information such as that shown in FIG. 4 by using the information obtained by the self-position information collection unit 133 and the other person's position information collection unit 134.

[0026] In communication system 70, communication device 101 mounted on vehicle 1 and communication device 201 mounted on vehicle 2 share free space information such as that shown in Fig. 4 with each other, thereby making it possible to identify not only locations where vehicles, obstacles, etc. exist, but also locations where no vehicles, obstacles, etc. exist. This allows application execution unit 100 of vehicle 1 and application execution unit 200 of vehicle 2 to use the free space information to help plan routes, for example, when changing lanes, entering an intersection, merging, leaving, etc.

[0027] 5 is a flowchart showing the operation of the communication device 101 according to the first embodiment. In the communication device 101 mounted on the vehicle 1, the free space information generating unit 130 included in the free space information sharing unit 103 collects self-location information, which is vehicle location information for the vehicle 1, and other-vehicle location information, which includes vehicle location information for other vehicles as well as location information for obstacles (step S1). The free space information generating unit 130 included in the free space information sharing unit 103 uses the self-location information and the other-vehicle location information to generate first free space information indicating a location where the vehicle 1, other vehicles, or obstacles are not present (step S2). The wireless communication unit 104 receives second free space information, which is generated by the communication device 201 mounted on the vehicle 2 and transmitted from the communication device 201 mounted on the vehicle 2 and indicates a location where the vehicle 2, other vehicles, or obstacles are not present, and transmits the first free space information to the communication device 201 (step S3). The order of transmission and reception in step S3 may be reversed. The free space information analysis unit 131 provided in the free space information sharing unit 103 shares the first free space information and the second free space information with the communication device 201 and analyzes the first free space information and the second free space information (step S4).

[0028] Although the operation of the communication device 101 has been described above, the communication device 201 also performs the same operation. In this case, in the above description, the components of the communication device 101 will be read as the components of the communication device 201. When viewed as a communication system 70, the free space information sharing unit 103 included in the communication device 101 and the free space information sharing unit 203 included in the communication device 201 can share the first free space information and the second free space information between the communication device 101 and the communication device 201 and can analyze the first free space information and the second free space information.

[0029] Next, the hardware configuration of the communication device 101 will be described. Note that the configuration of the communication device 201 is similar to that of the communication device 101, so the communication device 101 will be used as an example for the description. In the communication device 101, the wireless communication unit 104 is a communication device capable of wireless communication. The free space information sharing unit 103 is realized by a processing circuit. The processing circuit may be a processor and memory that executes a program stored in memory, or may be dedicated hardware. The processing circuit is also called a control circuit.

[0030] FIG. 6 is a diagram illustrating an example of the configuration of a processing circuit 90 that implements the communication device 101 according to the first embodiment when the processing circuit is implemented by a processor 91 and a memory 92. The processing circuit 90 illustrated in FIG. 6 is a control circuit and includes a processor 91 and a memory 92. When the processing circuit 90 is configured with the processor 91 and the memory 92, each function of the processing circuit 90 is implemented by software, firmware, or a combination of software and firmware. The software or firmware is written as a program and stored in the memory 92. The processing circuit 90 implements each function by having the processor 91 read and execute the program stored in the memory 92. That is, the processing circuit 90 includes the memory 92 for storing a program that results in the processing of the communication device 101 being executed. This program can also be said to be a program that causes the communication device 101 to execute each function implemented by the processing circuit 90. This program may be provided by a storage medium on which the program is stored, or by other means such as a communication medium.

[0031] The above program can also be said to be a program that causes the communication device 101 to execute the following steps: a free space information generation step in which the free space information sharing unit 103 collects self-location information, which is vehicle location information of vehicle 1, and other vehicle location information, which includes vehicle location information of other vehicles as well as location information of obstacles, and generates first free space information, which is free space information indicating a location where vehicle 1, other vehicles, or obstacles are not present; a communication step in which the wireless communication unit 104 receives second free space information, which is free space information indicating a location where vehicle 2, other vehicles, or obstacles are not present, transmitted from a communication device 201, which is a communication device mounted on vehicle 2, and transmits the first free space information to the communication device 201; and a free space information analysis step in which the free space information sharing unit 103 shares the first free space information and the second free space information with the communication device 201 and analyzes the first free space information and the second free space information.

[0032] Here, the processor 91 is, for example, a CPU (Central Processing Unit), a processing device, an arithmetic unit, a microprocessor, a microcomputer, or a DSP (Digital Signal Processor).The memory 92 is, for example, a non-volatile or volatile semiconductor memory such as a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory, an EPROM (Erasable Programmable ROM), or an EEPROM (Electrically EPROM), a magnetic disk, a flexible disk, an optical disk, a compact disk, a minidisk, or a DVD (Digital Versatile Disc).

[0033] FIG. 7 is a diagram illustrating an example of a processing circuit 93 that implements the communication device 101 according to the first embodiment when the processing circuit is configured with dedicated hardware. The processing circuit 93 illustrated in FIG. 7 may be, for example, a single circuit, a composite circuit, a programmed processor, a parallel-programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or a combination thereof. The processing circuit may be partially implemented with dedicated hardware and partially implemented with software or firmware. In this way, the processing circuit can implement each of the above-described functions using dedicated hardware, software, firmware, or a combination thereof.

[0034] As described above, according to this embodiment, in the communication device 101 mounted on the vehicle 1, the free space information generation unit 130 of the free space information sharing unit 103 collects self-location information, which is vehicle location information of the vehicle 1, and other-vehicle location information, which includes vehicle location information of other vehicles as well as location information of obstacles, and generates first free space information indicating a location where the vehicle 1, other vehicles, or obstacles are not present, using the self-location information and the other-vehicle location information. The wireless communication unit 104 receives second free space information transmitted from the communication device 201 mounted on the vehicle 2, and transmits the first free space information to the communication device 201. The free space information analysis unit 131 of the free space information sharing unit 103 shares the first free space information and the second free space information with the communication device 201, and analyzes the first free space information and the second free space information.

[0035] This allows the communication device 101 mounted on the vehicle 1 to share the first free space information and the second free space information with the communication device 201 mounted on another vehicle, the vehicle 2. By sharing the first free space information and the second free space information with the communication device 201, the communication device 101 can expand the coverage area of ​​the free space information, and by merging the free space information, the accuracy of the free space information can be improved.

[0036] Embodiment 2. In the above-described embodiment 1, free space information is shared between two vehicles, i.e., vehicle 1 and vehicle 2. However, free space information may be shared between more vehicles. For example, FIG. 8 shows a configuration diagram for sharing free space information between four vehicles. FIG. 8 is a diagram showing how free space information is shared by communication devices 501, 601, 701, and 801 mounted on four vehicles according to embodiment 2. Communication devices 501, 601, 701, and 801 are the same as communication devices 101 and 201 shown in FIG. 1 and described in embodiment 1.

[0037] By sharing free space information using communication devices 501, 601, 701, and 801, multiple vehicles can further expand the coverage area of ​​the free space information compared to the case in which free space information is shared by two communication devices 101 and 201 in embodiment 1, and can also improve the accuracy of the free space information by merging multiple pieces of free space information.

[0038] Embodiment 3. In the above-described embodiments 1 and 2, free space information is shared among a plurality of vehicles, but there are generally differences in the accuracy and granularity of the free space information that can be provided by different vehicles. In this case, a vehicle that acquires free space information can grasp in advance the free space information that other vehicles can provide, and then share the free space information only with other vehicles that can provide the necessary free space information, thereby reducing unnecessary communication, unnecessary processing, and the like.

[0039] Hereinafter, the accuracy and granularity of the free space information that each vehicle can provide will be referred to as capability. Figure 9 is a diagram showing an example of vehicle capability according to the third embodiment. The capability of a certain vehicle is defined as the area range for which free space information can be provided, and is expressed as a combination of the vehicle's position 1311 relative to the free space information 1310 and the width 1312 and height 1313 of the free space information 1310. The area range may also be expressed as a combination of position information 1314 to 1317 indicating the four corners of the free space information 1310.

[0040] Next, the operation for determining the capabilities of each vehicle in advance will be described. Hereinafter, the operation for determining the capabilities of each vehicle in advance will be referred to as discovery. Note that discovery may also be referred to as search. FIG. 10 is a sequence diagram showing the operation when a vehicle according to the third embodiment performs discovery. In FIG. 10, a case is considered in which four vehicles, 3 to 6, are present. Here, it is assumed that vehicle 5 is the vehicle that wishes to acquire free space information. Each vehicle broadcasts notification messages 1321 to 1324 using its own communication device to notify surrounding vehicles of information including its respective capabilities. The communication devices installed in each vehicle are the same as the communication devices 101 and 201 shown in FIG. 1 and described in the first embodiment. Vehicle 5 receives notification messages 1321, 1322, and 1324 from other vehicles, i.e., vehicles 3, 4, and 6, and selects a vehicle from which it can obtain the free space information it desires based on the capabilities included in the notification messages 1321, 1322, and 1324. If the capabilities of vehicle 3 match the desired free space information, vehicle 3 and vehicle 5 use each other's communication devices to perform communication 1325 to share the free space information.

[0041] In this way, by making each vehicle aware of its capabilities in advance through notification messages, the vehicles can obtain the necessary free space information without conducting unnecessary communication.

[0042] Embodiment 4. In the above-described embodiment 3, free space information is shared between two of the four vehicles, vehicle 3 and vehicle 5, namely vehicle 3 to vehicle 6. However, a vehicle that wishes to acquire free space information based on the capabilities acquired by transmitting and receiving a notification message may end up sharing the free space information with multiple vehicles. Figure 11 is a sequence diagram showing the operation of a vehicle according to embodiment 4 when sharing free space information with multiple vehicles after transmitting and receiving a notification message. Note that the operation of each vehicle broadcasting notification messages 1321 to 1324 using a communication device is the same as the operation in embodiment 3 shown in Figure 10. In Figure 11, vehicle 5 performs communications 1325 and 1326 to share free space information with vehicles 3 and 6, which have capabilities matching the desired free space information.

[0043] As in embodiment 2, multiple vehicles can expand the coverage area of ​​the free space information by sharing the free space information among multiple vehicles, and can also improve the accuracy of the free space information by merging multiple pieces of free space information.

[0044] Embodiment 5. In the above-described embodiments 3 and 4, in discovery, each vehicle voluntarily notifies surrounding vehicles of its capabilities by using a notification message, and vehicles that desire free space information passively utilize this information, but a vehicle that desires free space information may also be the starting point and actively search for the capabilities of surrounding vehicles.

[0045] FIG. 12 is a sequence diagram showing the operation of a vehicle according to the fifth embodiment, when a vehicle requesting free space information starts and actively searches for the capabilities of surrounding vehicles. In FIG. 12, a case is considered in which four vehicles (7 to 10) are present. Here, it is assumed that vehicle 9 is the vehicle requesting free space information. Vehicle 9 includes the capability for obtaining the desired free space information in a request message 1330 and broadcasts it using a communication device. The communication devices of each vehicle are the same as the communication devices 101 and 201 shown in FIG. 1 and described in the first embodiment. Vehicles 7, 8, and 10 confirm their own capabilities in response to the request message 1330 received by their communication devices, and if they determine that they can obtain the requested free space information, they transmit a response message. In FIG. 12, vehicle 7 determines that it can provide the free space information requested by vehicle 9 and transmits a response message 1331 to vehicle 9. Vehicle 9, having received the response message 1331 via its communication device, recognizes that this vehicle is capable of providing the free space information desired by vehicle 7. Vehicles 7 and 9 use their respective communication devices to perform communication 1332 for sharing free space information.

[0046] In this way, a vehicle desiring free space information can actively send a message, thereby searching for a vehicle that matches the desired capabilities with fewer messages sent and received compared to embodiment 4.

[0047] Taking into account the contents of embodiments 3 to 5, and using the communication device 101 shown in Figure 1, it can be said that the wireless communication unit 104 can actively or passively search for the capabilities of the second free space information that it wishes to acquire, and receive the second free space information that it wishes to acquire.

[0048] Sixth Embodiment In the fifth embodiment described above, one vehicle transmits a response message during discovery, but multiple vehicles may transmit response messages.

[0049] FIG. 13 is a sequence diagram showing the operation of a vehicle according to the sixth embodiment when a vehicle requesting free space information acts as a starting point to actively search for the capabilities of surrounding vehicles and multiple vehicles transmit response messages. In FIG. 13, as in the fifth embodiment, a case is considered in which four vehicles 7 to 10 are present. Here, it is assumed that vehicle 9 is the vehicle that wishes to obtain free space information. Vehicle 9 includes in a request message 1340 the capability that will enable it to obtain the free space information it desires, and broadcasts this request message using its communication device. Vehicles 7, 8, and 10 confirm their own capabilities in response to the request message 1340 received by their communication devices, and if they determine that they can obtain the requested free space information, they transmit a response message.

[0050] Here, vehicle 7 determines that it can acquire the requested free space information and transmits a response message 1341. Vehicle 10 also determines that it can acquire the requested free space information and transmits a response message 1342. Vehicle 9 receives response message 1341 from vehicle 7 and response message 1342 from vehicle 10, and, for example, selects vehicle 7 as the best vehicle based on their respective capabilities. Here, vehicle 9 transmits result message 1343 indicating that vehicle 7 has been selected. Vehicle 9 may broadcast result message 1343. By receiving result message 1343, vehicle 7 recognizes that it needs to provide free space information to vehicle 9. On the other hand, by receiving result message 1343, vehicle 10 recognizes that it does not need to provide free space information to vehicle 9. Thereafter, vehicle 7 and vehicle 9 use their respective communication devices to perform communication 1344 to share free space information.

[0051] In this way, vehicle 9 sends result message 1343 and vehicle 10 receives result message 1343, allowing vehicle 10 to recognize that it does not need to provide free space information, thereby avoiding unnecessary waiting for processing, unnecessary message transmission, etc.

[0052] Embodiment 7 In the above-described embodiment 6, a vehicle desiring free space information selects only one vehicle as a target for sharing the free space information in discovery, but multiple vehicles may be selected based on the contents of a response message as a result of sharing the free space information.

[0053] FIG. 14 is a sequence diagram showing the operation of a vehicle according to the seventh embodiment, in which a vehicle requesting free space information actively searches for the capabilities of surrounding vehicles, and multiple vehicles transmit response messages, and the multiple vehicles are identified as targets for sharing free space information based on the contents of the response messages. In FIG. 14, as in the sixth embodiment, a case is considered in which four vehicles 7 to 10 are present. Here, it is assumed that vehicle 9 is the vehicle requesting free space information. Vehicle 9 includes the capability that will enable it to obtain the free space information it desires in a request message 1350 and broadcasts it using a communication device. Vehicles 7, 8, and 10 confirm their own capabilities in response to the request message 1350 received by their communication devices, and if they determine that they can obtain the requested free space information, they transmit a response message.

[0054] Here, vehicle 7 determines that it can acquire the requested free space information and transmits a response message 1351. Vehicle 10 also determines that it can acquire the requested free space information and transmits a response message 1352. Vehicle 8 also determines that it can acquire the requested free space information and transmits a response message 1353. Vehicle 9 receives response message 1351 from vehicle 7, response message 1352 from vehicle 10, and response message 1353 from vehicle 8, and as a result of the selection, selects vehicles 7 and 8 as targets for sharing the free space information. Here, vehicle 9 transmits a result message 1354 indicating that vehicles 7 and 8 have been selected. Vehicle 9 may broadcast the result message 1354. By receiving the result message 1354, vehicles 7 and 8 recognize that they need to provide free space information to vehicle 9. On the other hand, vehicle 10, by receiving the result message 1354, recognizes that it does not need to provide free space information to vehicle 9. Thereafter, vehicle 9 performs communication 1355 with vehicles 7 and 8 using their respective communication devices to share free space information.

[0055] As in embodiment 6, vehicle 9 sends result message 1354, and vehicle 10 receives result message 1354, allowing vehicle 10 to recognize that there is no need to provide free space information, thereby avoiding unnecessary waiting for processing, unnecessary message transmission, etc.

[0056] Embodiment 8. In the above-described embodiments 3 to 7, discovery searches for capabilities from an unspecified number of vehicles, but vehicles may also be searched for in units of predefined groups. For example, in the case of a group of vehicles such as a platoon, there is a rule that free space information must be provided to the leading vehicle and the trailing vehicle, and if such a rule is known in advance, the vehicle searches for group members that require free space information.

[0057] FIG. 15 is a sequence diagram showing the operation of a vehicle according to the eighth embodiment when passively searching for group members who require free space information. In FIG. 15, a case is considered in which four vehicles 11 to 14 are present. Here, it is assumed that vehicle 13 is a vehicle capable of acquiring free space information. Vehicle 13 uses a communication device to groupcast the capability of the free space information it can provide as a group member notification message 1361. The communication devices of each vehicle are the same as the communication devices 101 and 201 shown in FIG. 1 and described in the first embodiment. It is assumed that vehicles 11 and 14 are group members for the free space information provided by vehicle 13. Since vehicles 11 and 14 are members of a group that desires free space information from vehicle 13, they receive the group member notification message 1361. On the other hand, vehicle 12, which is not a group member, does not receive the group member notification message 1361. Vehicle 11, which has received group member notification message 1361, detects that vehicle 13 can provide free space information, and uses each other's communication devices to carry out communication 1362 for sharing the free space information. Vehicle 14, which has received group member notification message 1361, detects that vehicle 13 can provide free space information, and uses each other's communication devices to carry out communication 1363 for sharing the free space information.

[0058] In this way, when a vehicle capable of providing free space information knows in advance which vehicle group the free space information should be provided to, it uses the above procedure to not provide the free space information to vehicles that do not require the free space information, such as vehicle 12 in the example of Figure 15. This allows vehicles capable of providing free space information to avoid communication for sharing unnecessary free space information. Furthermore, vehicles 12 that do not require free space information do not need to perform processes such as receiving and decoding messages, thereby reducing unnecessary processing.

[0059] Ninth Embodiment In the eighth embodiment described above, group member discovery is performed passively, but similar to the fifth embodiment, group member discovery may also be performed actively.

[0060] FIG. 16 is a sequence diagram showing the operation of a vehicle according to the ninth embodiment when actively searching for group members who require free space information. In FIG. 16, as in the eighth embodiment, a case is considered in which four vehicles 11 to 14 are present. Here, it is assumed that vehicle 13 is the vehicle that wishes to obtain free space information. Vehicle 13 includes a capability that enables it to obtain the free space information it desires in a group member request message 1370, and groupcasts the message using a communication device. It is assumed that vehicles 11 and 12 are members of the group that has the free space information desired by vehicle 13. Since vehicles 11 and 12 are group members for the free space information of vehicle 13, they receive the group member request message 1370. On the other hand, vehicle 14, which is not a group member, does not receive the group member request message 1370.

[0061] Vehicle 11, which has received the group member request message 1370, transmits a group member response message 1371 to vehicle 13. Vehicle 12, which has received the group member request message 1370, transmits a group member response message 1372 to vehicle 13. Vehicle 13 receives the group member response message 1371 transmitted from vehicle 11, and performs communication 1373 between vehicle 13 and vehicle 11 using each other's communication devices to share free space information. Vehicle 13 also receives the group member response message 1372 transmitted from vehicle 12, and performs communication 1373 between vehicle 13 and vehicle 12 using each other's communication devices to share free space information.

[0062] In this way, when a vehicle capable of providing free space information knows in advance which vehicle group the free space information should be provided to, it uses the above procedure to not provide the free space information to vehicles that do not require the free space information, such as vehicle 14 in the example of Figure 16. This allows vehicles capable of providing free space information to avoid communication for sharing unnecessary free space information. Furthermore, vehicles 14 that do not require free space information do not need to perform processes such as receiving and decoding messages, thereby reducing unnecessary processing.

[0063] Tenth Embodiment In the first to ninth embodiments described above, the wireless communication method of the wireless communication unit included in the communication device is not particularly limited. In the tenth embodiment, a case will be described in which C-V2X, which is being standardized by 3GPP (registered trademark) (Third Generation Partnership Project), is used as the wireless communication method of the wireless communication unit.

[0064] 17 is a diagram illustrating a configuration example of a communication system 70a according to a tenth embodiment. The communication system 70a includes a vehicle 15 and a vehicle 16. The communication system 70a is a system in which free space information is shared between the vehicles 15 and 16. The vehicle 15 includes an application execution unit 300 and a communication device 301. The communication device 301 includes a free space information sharing unit 303 and a C-V2X communication unit 304. The vehicle 16 includes an application execution unit 400 and a communication device 401. The communication device 401 includes a free space information sharing unit 403 and a C-V2X communication unit 404. In the communication system 70a, the vehicles 15 and 16 share free space information using C-V2X as the wireless communication method of the communication devices 301 and 401.

[0065] In the following description, vehicle 15 will be referred to as the first vehicle, vehicle 16 will be referred to as the second vehicle, communication device 301 will be referred to as the first communication device, communication device 401 will be referred to as the second communication device, free space information generated by communication device 301 of vehicle 15 will be referred to as the first free space information, and free space information generated by communication device 401 of vehicle 16 will be referred to as the second free space information. Also, free space information sharing unit 303 will be referred to as the first free space information sharing unit, free space information sharing unit 403 will be referred to as the second free space information sharing unit, C-V2X communication unit 304 will be referred to as the first communication unit, and C-V2X communication unit 404 will be referred to as the second communication unit.

[0066] The application execution units 300 and 400 execute applications such as automated driving and safe driving support systems in each vehicle. Note that the applications executed by the application execution units 300 and 400 are not limited to these. Furthermore, the number of applications simultaneously executed by the application execution units 300 and 400 is not limited to one, and multiple applications may be executed simultaneously.

[0067] The communication device 301 and the communication device 401 are communication devices installed in each vehicle for sharing free space information. The communication device 301 is connected to the application execution unit 300 via an interface 302. The communication device 401 is connected to the application execution unit 400 via an interface 402. In the communication device 301, the free space information sharing unit 303 and the C-V2X communication unit 304 are connected via an interface 305. In the communication device 401, the free space information sharing unit 403 and the C-V2X communication unit 404 are connected via the interface 405. The C-V2X communication unit 304 and the C-V2X communication unit 404 are connected via a PC5 interface 910 in 3GPP.

[0068] The C-V2X communication unit 304 and the C-V2X communication unit 404 are communication units that perform wireless communication between vehicles. As described above, C-V2X is used as the wireless communication method between the C-V2X communication unit 304 and the C-V2X communication unit 404.

[0069] Next, an operation will be described when the communication device 301 transmits free space information of the host vehicle 15 to the communication device 401 of the other vehicle 16. Controlled by the application execution unit 300 via the interface 302, the free space information sharing unit 303 generates and analyzes free space information and transmits the free space information to the C-V2X communication unit 304 via the interface 305. The C-V2X communication unit 304 transmits the free space information to the C-V2X communication unit 404 via the PC5 interface 910. This transmission is performed by Direct Communication in 3GPP ProSe via the PC5 interface described in "3GPP TS 23.304 V18.3.0 "Proximity based Services (ProSe) in the 5G System (5GS)", and communication is performed in Unicast mode. The C-V2X communication unit 404 transmits the free space information to the free space information sharing unit 403 via an interface 405. The free space information sharing unit 403 provides the free space information to the application execution unit 400 via an interface 402.

[0070] In this way, by using the C-V2X communication unit 304, vehicles can stably communicate to share free space information even in environments where high-speed movement, multipath propagation, etc. occur, and by utilizing standardized signaling, unnecessary processing in the application execution unit 300 can be reduced.

[0071] Embodiment 11. In the above-described embodiment 10, free space information is shared between two vehicles using the C-V2X communication unit 304 as a wireless communication unit, but free space information may also be shared between a larger number of vehicles. When free space information is to be shared simultaneously with an unspecified number of surrounding vehicles, communication between the C-V2X communication unit 304 and the C-V2X communication unit 404 via the PC5 interface 910 in FIG. 17 may be performed in broadcast mode. Furthermore, when it is known in advance that free space information will be shared only with a specific group of vehicles, communication may be performed in groupcast mode.

[0072] In this way, by vehicles 15 and 16 using the Broadcast mode, Groupcast mode, etc., vehicles that do not need free space information do not need to perform processes such as receiving and decoding messages, thereby reducing unnecessary processing.

[0073] Embodiment 12. In the above-described embodiments 3 to 9, the wireless communication method of the wireless communication unit was not particularly limited when discovering the capability of free space information. When the C-V2X communication unit 304 is used as the wireless communication unit, Direct Discovery in 3GPP ProSe may be used. A vehicle that wishes to acquire free space information uses Model A Discovery when discovering a vehicle that passively provides free space information, and uses Model B Discovery when discovering a vehicle that actively provides free space information.

[0074] 18 is a sequence diagram showing an operation when a vehicle according to a twelfth embodiment uses a C-V2X communication unit as a wireless communication unit and utilizes Model A Discovery in ProSe Direct Discovery for discovery. In FIG. 18, a case is considered in which four vehicles 17 to 20 are present. The communication devices mounted on each vehicle are the same as the communication devices 301 and 401 shown in FIG. 17 described in the tenth embodiment. Here, it is assumed that vehicle 19 is a vehicle that wishes to acquire free space information. Vehicle 17 broadcasts an Announcement message 1380. In 3GPP standardization, this Announcement message 1380 includes a Type of Discovery Message, a ProSe Application Code, a ProSe Restricted Code, a Relay Indication, a Security protection element, and the like.

[0075] The capability related to free space information may be included in various fields. For example, by preparing a code for sharing free space information in one of the ProSe Application Code, ProSe Restricted Code, etc., it is possible to clearly indicate that the vehicle 17 can provide free space information. Furthermore, the capability may be included in a metadata field prepared in addition to various fields, or the provideable free space information may be expressed by a combination of these. The vehicle 19 that receives the Announcement message 1380 recognizes that the vehicle 17 has the capability for the desired free space information and performs communication to share the free space information by ProSe Direct Communication 1381. In this case, a vehicle using a C-V2X communication unit may communicate in any mode among the Broadcast mode, Groupcast mode, and Unicast mode.

[0076] 19 is a sequence diagram showing an operation when a vehicle according to embodiment 12 uses a C-V2X communication unit as a wireless communication unit and utilizes Model B Discovery in ProSe Direct Discovery for discovery. Consider a case where four vehicles 17 to 20 are present. Here, it is assumed that vehicle 19 is a vehicle that wishes to acquire free space information. Vehicle 19 broadcasts a Solicitation Message 1390 to communicate that it wishes to acquire free space information. In 3GPP standardization, the Solicitation Message 1390 includes a Type of Discovery Message, a ProSe Application Code, a ProSe Restricted Code, a Relay Indication, a Security protection element, and the like.

[0077] For example, by preparing a code for sharing free space information in one of the ProSe Application Code, ProSe Restricted Code, etc., it is possible to clearly indicate that the vehicle 19 wishes to obtain free space information. Upon receiving the Solicitation Message 1390, the vehicle 17 transmits a Response Message 1391. In the 3GPP standardization, the Response Message 1391 includes a Type of Discovery Message, a ProSe Response Code, a Relay Indication, a Security Protection Element, etc.

[0078] The capability for free space information may be included in various fields. For example, by preparing a code for sharing free space information in one of the ProSe Response Codes, it is possible to clearly indicate that the vehicle 17 can provide free space information. Furthermore, the capability may be included in a metadata field prepared in addition to various fields, and the provideable free space information may be expressed by a combination of these. The vehicle 19 that receives the Response Message 1391 recognizes that the vehicle 17 can provide free space information and performs communication to share the free space information using ProSe Direct Communication 1392. At this time, the vehicle using the C-V2X communication unit may perform communication in any mode among the Broadcast mode, Groupcast mode, and Unicast mode.

[0079] In this way, even when a vehicle uses a C-V2X communication unit, it can obtain the same effects as when it uses a wireless communication unit that is not limited to a wireless communication method.

[0080] Taking the content of the twelfth embodiment into consideration, when explaining using the communication device 301 shown in FIG. 17, it can be said that the C-V2X communication unit 304 can actively or passively search for the capability of the second free space information that it wishes to acquire by ProSe Direct Discovery, and can receive the second free space information that it wishes to acquire by ProSe Direct Communication.

[0081] Embodiment 13 In the above-described embodiment 12, capabilities are searched for from an unspecified number of vehicles in discovery. However, as in embodiment 8, Group Member Discovery in 3GPP ProSe may be used to search for vehicles in units of a predetermined group.

[0082] 20 is a sequence diagram showing an operation when a vehicle according to a thirteenth embodiment uses a C-V2X communication unit as a wireless communication unit and utilizes Model A Discovery in Group Member Discovery for discovery. In FIG. 20, a case is considered in which four vehicles 21 to 24 are present. The communication devices mounted on each vehicle are the same as the communication devices 301 and 401 shown in FIG. 17 described in the tenth embodiment. Here, it is assumed that the vehicle 23 is a vehicle capable of providing free space information. The vehicle 23 transmits a Group member discovery announcement message 1400 to clearly indicate that the vehicle is capable of providing free space information. In 3GPP standardization, the Group member discovery announcement message 1400 includes a Type of Discovery Message, Announcer Info, and an Application Layer Group ID. For example, by including a capability in the Announcer Info, it is possible to clearly indicate that the vehicle 23 can provide free space information.

[0083] Vehicles 21 and 24 that receive Group member discovery announcement message 1400 recognize that vehicle 23 is able to provide free space information. Vehicle 23 communicates with vehicle 21 to share the free space information using ProSe Direct Communication 1401, and communicates with vehicle 24 to share the free space information using ProSe Direct Communication 1402. At this time, communication may be performed in any mode among Broadcast mode, Groupcast mode, and Unicast mode.

[0084] 21 is a sequence diagram showing an operation when a vehicle according to embodiment 13 uses a C-V2X communication unit as a wireless communication unit and utilizes Model B Discovery in Group Member Discovery for discovery. In FIG. 21 , a case is considered in which four vehicles 21 to 24 are present. Here, it is assumed that vehicle 23 is a vehicle that wishes to acquire free space information. Vehicle 23 transmits Group member discovery solicitation message 1410 to clearly indicate that it wishes to acquire free space information. In 3GPP standardization, the Group member discovery solicitation message 1410 includes a Type of Discovery Message, Discoverer Info, an Application Layer Group ID, and Target Info. For example, by including a capability to be acquired in the Discoverer Info, it is possible to clearly indicate that the vehicle 23 wishes to acquire free space information.

[0085] Vehicles 21 and 22 receive Group member discovery solicitation message 1410. Vehicle 21 transmits Group member discovery response message 1411. Vehicle 22 transmits Group member discovery response message 1412. In 3GPP standardization, the Group member discovery response messages 1411 and 1412 include a Type of Discovery Message, Discovery Info, and an Application Layer Group ID. For example, by including a capability in the Discovery Info, it is possible to clearly indicate that the vehicles 21 and 22 can provide the free space information desired by the vehicle 23.

[0086] Vehicle 23 receives Group member discovery response messages 1411 and 1412, recognizes that vehicles 21 and 22 are capable of providing free space information, and performs communication to share the free space information between vehicles 21 and 22 via ProSe Direct Communication 1413. At this time, communication may be performed in any mode among Broadcast mode, Groupcast mode, and Unicast mode.

[0087] In this way, even when a vehicle uses a C-V2X communication unit to search for vehicles on a group basis, it can obtain the same effect as when a wireless communication unit with no limited wireless communication method is used to search for vehicles on a group basis.

[0088] Embodiment 14 In the above-described embodiments 1 to 13, the communication between a vehicle requesting free space information and a vehicle providing the free space information is single-hop communication, but it may be multi-hop communication via a relay vehicle in between.

[0089] 22 is a sequence diagram showing the operation of a vehicle according to embodiment 14 when communication between a vehicle requesting free space information and a vehicle providing free space information is multi-hop. In FIG. 22, there are four vehicles, vehicles 25 to 28, where vehicle 25 is the vehicle providing free space information, vehicle 28 is the vehicle requesting free space information, and vehicles 26 and 27 are relay vehicles. The communication devices mounted on each vehicle are the same as the communication devices 101 and 201 shown in FIG. 1 and described in embodiment 1. When the free space information provided by vehicle 25 is relayed by vehicle 26 and provided to vehicle 28, communication 1420 for sharing the free space information is performed between vehicles 25 and 26, and then communication 1421 for sharing the free space information is performed between vehicles 26 and 28. The communications between vehicles 25 and 26 and the communications between vehicles 26 and 28 may be performed alternately, as in communications 1420 and 1421, or, if the relaying vehicle 26 has the ability to retain data, as in communications 1422 and 1423, some buffering may be performed and communication 1423 may be performed after communication 1422 has ended.

[0090] The number of relay vehicles may also be increased. For example, when relaying both vehicle 26 and vehicle 27, vehicle 25 may provide free space information to vehicle 28 by performing multi-stage relaying, such as communication 1424 between vehicle 25 and vehicle 26, communication 1425 between vehicle 26 and vehicle 27, and communication 1426 between vehicle 27 and vehicle 28. Vehicle 25 may use a pre-defined vehicle as a relay vehicle, or may select a vehicle from an unspecified number of vehicles. Unlike discovery of the capability of free space information, relay vehicles do not necessarily need to be vehicles capable of obtaining free space information. For example, even vehicles that do not have on-board sensors or the ability to acquire their own location can be used as relay vehicles as long as they are capable of communication.

[0091] FIG. 23 is a sequence diagram showing the operation of selecting a relay vehicle in a vehicle according to the fourteenth embodiment. In FIG. 23, it is assumed that there are four vehicles, vehicles 25 to 28, and vehicle 27 is a vehicle with relay capability. Vehicle 27 broadcasts relay notification message 1430 to indicate that it is a vehicle capable of relay transmission. Upon receiving relay notification message 1430, vehicle 25 recognizes that vehicle 27 is a vehicle with relay capability and communicates with vehicle 28 via vehicle 27 to share free space information. Specifically, communication between vehicle 25 and vehicle 28 is performed by communication 1431 between vehicle 25 and vehicle 27 and communication 1432 between vehicle 27 and vehicle 28.

[0092] In this way, by combining relay transmission by a relay vehicle, vehicles can share free space information between vehicles in an environment where direct communication is difficult.

[0093] Embodiment 15 In the above-described embodiment 14, the relay vehicle is selected passively in multi-hop communication for sharing free space information, but the relay vehicle may be selected actively.

[0094] FIG. 24 is a sequence diagram showing the operation of a vehicle according to the fifteenth embodiment when actively selecting a relay vehicle. In FIG. 24 , it is assumed that there are four vehicles, vehicles 25 to 28, vehicles 26 and 27 have relay capabilities, and vehicles 25 and 28 are vehicles that wish to share free space information. When vehicle 25 is unable to communicate directly with vehicle 28, it broadcasts a relay request message 1440 to search for a relay vehicle. Vehicle 27, which has received relay request message 1440, requests vehicle 28 to relay transmission from vehicle 25 by transmitting relay request message 1441. Vehicle 26, which has received relay request message 1440, also has relay capabilities by transmitting relay request message 1442, requests vehicle 28 to relay transmission from vehicle 25.

[0095] Vehicle 28 receives relay request message 1441 from vehicle 27 and transmits relay response message 1443 in response thereto. Vehicle 28 also receives relay request message 1442 from vehicle 26 and transmits relay response message 1444 in response thereto. Vehicle 27, having received relay response message 1443, transmits relay response message 1445 to vehicle 25 to indicate that relay transmission to vehicle 28 is possible. Vehicle 26, having received relay response message 1444, transmits relay response message 1446 to vehicle 25 to indicate that relay transmission to vehicle 28 is possible.

[0096] By receiving relay response message 1445 and relay response message 1446, vehicle 25 recognizes that relay transmission to vehicle 28 via vehicles 26 and 27 is possible, and can communicate to share free space information via multi-hop communication via vehicles 26 and 27.

[0097] Embodiment 16. In the above-described embodiments 14 and 15, the wireless communication method of the wireless communication unit is not particularly limited. However, the vehicle may use, as the wireless communication unit, a C-V2X communication unit capable of C-V2X communication, which is being standardized by 3GPP. In this case, multi-hop communication may be realized by ProSe UE-to-UE Layer 3 Relay or ProSe UE-to-UE Layer 2 Relay. Furthermore, selection of a relay vehicle may be realized by ProSe UE-to-UE Relay Discovery.

[0098] 25 is a sequence diagram showing the operation when a vehicle according to embodiment 16 uses ProSe UE-to-UE Relay Model A Discovery to select a relay vehicle. In FIG. 25, it is assumed that there are four vehicles, vehicles 25 to 28, and vehicle 27 is a vehicle with relay functionality. The communication devices mounted on each vehicle are the same as the communication devices 301 and 401 shown in FIG. 17 and described in embodiment 10. Vehicle 27 broadcasts a UE-to-UE Relay Discovery Announcement message 1450 to clearly indicate that it is a vehicle capable of relay transmission. In the 3GPP standard, the UE-to-UE Relay Discovery Announcement message 1450 includes a Type of Discovery Message, a User Info ID of the relay vehicle, a Relay Service Code (RSC), and a list of User Info IDs of terminal vehicles that support the RSC. In the example of FIG. 25, the terminal vehicle is vehicle 28. Vehicles for relaying free space information are managed by the RSC and a User Info ID list linked to the RSC.

[0099] Vehicle 25 recognizes that vehicle 27 is a vehicle with a relay function by receiving UE-to-UE Relay Discovery Announcement message 1450. Vehicle 25 performs communication via vehicle 27 to vehicle 28 using ProSe Direct Communication for sharing free space information, specifically, communication 1451 between vehicle 25 and vehicle 27 and communication 1452 between vehicle 27 and vehicle 28.

[0100] Embodiment 17 In the above-described embodiment 16, a relay vehicle is passively selected by ProSe UE-to-UE Relay Model A Discovery, but a relay vehicle may also be actively selected by using ProSe UE-to-UE Relay Model B Discovery.

[0101] 26 is a sequence diagram showing the operation of a vehicle according to Embodiment 17 when actively selecting a relay vehicle using ProSe UE-to-UE Relay Model B Discovery. In FIG. 26, it is assumed that there are four vehicles, vehicles 25 to 28, that vehicles 26 and 27 have relay functionality, and that vehicles 25 and 28 are vehicles that seek to share free space information. When vehicle 25 cannot communicate directly with vehicle 28, it broadcasts a UE-to-UE Relay Discovery Solicitation message 1460 to search for a relay vehicle. In the 3GPP standardization, the UE-to-UE Relay Discovery Solicitation message 1460 includes a Type of Discovery Message, its own User Info ID, an RSC, and a list of User Info IDs of the terminating vehicle. In the example of Fig. 26, the terminating vehicle is vehicle 28. Vehicles for relaying free space information are managed by the RSC and the User Info ID list.

[0102] Vehicle 27, which has received UE-to-UE Relay Discovery Solicitation message 1460, has a relay function and requests vehicle 28 to relay transmission from vehicle 25 by transmitting UE-to-UE Relay Discovery Solicitation message 1461. Vehicle 26, which has received UE-to-UE Relay Discovery Solicitation message 1460, has a relay function and requests vehicle 28 to relay transmission from vehicle 25 by transmitting UE-to-UE Relay Discovery Solicitation message 1462. In 3GPP standardization, UE-to-UE Relay Discovery Solicitation messages 1461 and 1462 include a Type of Discovery Message, User Info IDs of the vehicle that wishes to obtain free space information and the vehicle that provides free space information, and the User Info ID of the relay vehicle.

[0103] Vehicle 28 receives UE-to-UE Relay Discovery Solicitation message 1461 from vehicle 27 and transmits a UE-to-UE Relay Discovery Response message 1463 in response thereto. Vehicle 28 also receives UE-to-UE Relay Discovery Solicitation message 1462 from vehicle 26 and transmits a UE-to-UE Relay Discovery Response message 1464 in response thereto. In 3GPP standardization, the UE-to-UE Relay Discovery Response messages 1463 and 1464 include a Type of Discovery Message, an RSC, and User Info IDs of the vehicle that wishes to obtain free space information and the vehicle that provides the free space information.

[0104] Vehicle 27, which has received UE-to-UE Relay Discovery Response message 1463, transmits UE-to-UE Relay Discovery Response message 1465 to vehicle 25 to indicate that relay transmission to vehicle 28 is possible. Vehicle 26, which has received UE-to-UE Relay Discovery Response message 1464, transmits UE-to-UE Relay Discovery Response message 1466 to vehicle 25 to indicate that relay transmission to vehicle 28 is possible. In the 3GPP standardization, the UE-to-UE Relay Discovery Response messages 1465 and 1466 include a Type of Discovery Message, the User Info ID of the relay vehicle, the RSC, and the User Info ID of the terminal vehicle.

[0105] By receiving the UE-to-UE Relay Discovery Response messages 1465 and 1466, vehicle 25 can recognize that relay transmission to vehicle 28 via vehicles 26 and 27 is possible, and can perform communication to share free space information via multi-hop communication via vehicles 26 and 27.

[0106] Taking the contents of the sixteenth and seventeenth embodiments into consideration, the following description will be given using the communication device 301 shown in FIG. 17. It can be said that the C-V2X communication unit 304 actively or passively searches for the capability of the second free space information that the C-V2X communication unit 304 wishes to acquire by ProSe UE-to-UE Relay Discovery, and can receive the second free space information that the C-V2X communication unit 304 wishes to acquire by multi-hop ProSe Direct Communication.

[0107] Embodiment 18. In the above-described embodiments 1 to 17, free space information is shared between a plurality of vehicles by single communication or multi-hop communication, but if a conflict occurs regarding the content of the free space information as a result of sharing the free space information, the vehicles may resolve the conflict. Note that, as described in embodiment 1, in the example of embodiment 1, the conflict resolution in the vehicle is performed by the free space information analysis unit 131 provided in the free space information sharing unit 103.

[0108] 3 and 4, free space information generated from information obtained by the self-location information collection unit 133 and the other person's location information collection unit 134 included in the free space information generation unit 130 is analyzed by the free space information analysis unit 131. Because the free space information is based on the results obtained by the free space information generation unit 130 of each vehicle, differences in the capabilities of on-board sensors, differences in measurement conditions, etc. may result in differences in the content of free space information even for the same location. Therefore, when multiple vehicles share free space information and obtain multiple pieces of free space information for overlapping locations, the content may conflict.

[0109] 27 is a diagram showing an example in which a conflict occurs in free space information shared by multiple vehicles according to embodiment 18. In FIG. 27, free space information 1510 to 1512 is free space information for vehicles A to C, respectively, at the same location. Comparing information elements 1513 to 1515 in free space information 1510 to 1512, it is found that, at the same location, vehicle A has information element 1513 as the object presence space 1303, vehicle C has information element 1515 as the object presence space 1303, while vehicle B has information element 1514 as the uncertain space 1304. Furthermore, comparing information elements 1516 to 1518 in free space information 1510 to 1512, it is found that vehicle A has information element 1516 as the object presence space 1303, vehicle B has information element 1517 as the free space 1302, and vehicle C has information element 1518 as the free space 1302.

[0110] One possible solution to the conflict in free space information between vehicles is to adopt the result with the greater number of determinations. For example, for information elements 1513 to 1515, the result of the object presence space 1303 with the greater number of determinations can be adopted. With this method, the greater the degree of overlap in the free space information shared between vehicles, the greater the diversity and thus the higher the reliability. Therefore, it is important to consider this overlap in capability discovery when selecting vehicles with which to share free space information. On the other hand, attempting to share free space information with more vehicles consumes communication resources, and there is a trade-off between these two. Therefore, by setting a policy in advance, it is possible to avoid acquiring more duplicate information than necessary.

[0111] As a result of receiving notification messages, response messages, and the like obtained in discovery, the degree of redundancy of free space information for the desired area can be calculated. Here, if free space information is obtained from N vehicles for a certain location, the degree of redundancy is calculated as N. For example, if information is obtained from only one vehicle, the degree of redundancy is 1, and if information is obtained from two vehicles, the degree of redundancy is 2. Furthermore, if information is not obtained from any vehicle, the degree of redundancy is set to 0. For example, a pre-defined policy may require that the degree of redundancy of the information elements in the obtained free space information be at least 1. All possible combinations of free space information are investigated, and the degree of redundancy of the information elements is calculated. In this case, it is important for the vehicle to select a combination of free space information that minimizes the number of information elements with a redundancy of 0 in the desired area. For example, the vehicle selects a combination that minimizes the cost function, where "cost function = number of information elements with a redundancy of 0."

[0112] Fig. 28 is a diagram showing an example of the results when a vehicle according to embodiment 18 combines multiple pieces of free space information. In the case where there are three free space information combination patterns 1523 to 1525 as shown in Fig. 28, when the vehicle calculates the cost function, the cost function for free space information combination pattern 1523 is 3, the cost function for free space information combination pattern 1524 is 0, and the cost function for free space information combination pattern 1525 is 2. Therefore, in the example shown in Fig. 28, the vehicle selects free space information combination pattern 1524.

[0113] The vehicle can also select a combination based on the average value of the overlapping degrees. For example, the vehicle may use a cost function of "sum of overlapping degrees of information elements / number of information elements." In this cost function, the cost function for the combination pattern 1523 of free space information is approximately 1.83, the cost function for the combination pattern 1524 of free space information is approximately 3.92, and the cost function for the combination pattern 1525 of free space information is 2.5. If the target average value of overlapping degrees is 3, the combination pattern 1524 of free space information is slightly excessive, while the combination pattern 1525 of free space information is below the average value but does not result in a surplus. Therefore, the vehicle may select the combination pattern 1525 of free space information when, for example, it is desired to limit communication resources.

[0114] The above-described cost functions and selection criteria are merely examples, and various methods are possible depending on the application, requirements, and the like. This embodiment is not limited to the above-described method, and any method may be used to select an optimal combination from the obtained free space information. For example, if a fail-safe approach is followed, it is also possible to treat the free space information in which even one conflict has occurred as uncertain space 1304. In this case, when the application execution units 100 and 200 shown in FIG. 1 or the application execution units 300 and 400 shown in FIG. 17 acquire free space information in which a conflict has been resolved from a free space information analysis unit provided in a connected communication device, the application execution units 100 and 200 shown in FIG. 1 and the application execution units 300 and 400 shown in FIG. 17 only advance into the free space 1302 when the vehicle changes lanes, enters an intersection, merges, or leaves, and do not advance into the object presence space 1303 or uncertain space 1304.

[0115] As described above, by considering the degree of redundancy of free space information at the discovery stage, vehicles can share free space information with an appropriate level of accuracy for their requirements, while also reducing the consumption of communication resources.

[0116] Embodiment 19. In the above-described embodiment 18, free space information is shared at an appropriate overlapping level, taking into account the possibility of conflicts occurring when sharing free space information. However, when a conflict actually occurs, the conflict may be resolved by having other vehicles provide additional free space information. If free space information is provided by a vehicle and a conflict occurs as a result of integrating the provided free space information, restarting the discovery process from the time the conflict occurred to obtain new free space information from other vehicles would result in a significant delay before new free space information is obtained. Therefore, an embodiment will be described below for quickly selecting a vehicle that will provide new free space information when a conflict occurs.

[0117] FIG. 29 is a first sequence diagram showing the operation of vehicles according to the nineteenth embodiment when a conflict occurs during the sharing of free space information and the vehicle from which new free space information is to be quickly provided is selected. In FIG. 29, six vehicles, vehicles 29 to 34, are present. Vehicle 29 is the vehicle that wishes to obtain free space information, and of vehicles 30 to 34, vehicles 30 to 33 are vehicles that can provide free space information. The communication devices installed in each vehicle are the same as the communication devices 101 and 201 shown in FIG. 1 and described in the first embodiment. First, vehicle 29 includes in its request message 1470 the capability that enables it to obtain the free space information it desires, and broadcasts this message using the communication device. Each vehicle confirms its own capability in response to the request message 1470 received by its communication device, and if it determines that it can obtain the requested free space information, it transmits a response message 1471. In FIG. 29, vehicles 30 to 33 determine that they can provide the free space information requested by vehicle 29 and transmit a response message 1471 to vehicle 29.

[0118] Vehicle 29, which has received response message 1471 via its communication device, recognizes that vehicles 30 to 33 are vehicles that can provide the desired free space information, and after comparing the capabilities of these vehicles, selects vehicles 30 and 31 as primary response vehicles and vehicles 32 and 33 as secondary response vehicles. Here, the primary response vehicles are vehicles that share free space information the first time. The secondary response vehicles are vehicles that share free space information the second time in order to resolve a conflict that occurred during the first sharing of free space information. Vehicle 29 transmits result message 1472 to specify that vehicles 30 and 31 are primary response vehicles and vehicles 32 and 33 are secondary response vehicles.

[0119] Vehicles 30 to 33 that received result message 1472 each recognize whether they are a primary response vehicle or a secondary response vehicle. Then, communication 1473 for sharing free space information is performed between vehicles 30 and 31, which are primary response vehicles, and vehicle 29. If vehicle 29 determines as a result of communication 1473 that there is no conflict in the shared free space information and that further sharing of free space information is unnecessary, it transmits resolution message 1476 to vehicles 32 and 33, which are secondary response vehicles, to notify them that sharing of free space information is unnecessary. By receiving resolution message 1476, vehicles 32 and 33 recognize that they do not need to provide free space information to vehicle 29. This operation eliminates the need for vehicles 32 and 33 to retain the free space information to be provided for vehicle 29 for an unnecessarily long period of time.

[0120] On the other hand, if a conflict occurs in the free space information of vehicles 30 and 31 as a result of communication 1473, vehicle 29 transmits a conflict message 1474 to request vehicles 32 and 33, which are secondary response vehicles, to share their free space information, as shown in FIG. 30 . FIG. 30 is a second sequence diagram showing the operation of a vehicle according to embodiment 19 when a conflict occurs during the sharing of free space information and the vehicle selects a vehicle that will quickly provide new free space information. In FIG. 30 , the operation from vehicle 29 broadcasting the request message 1470 to communication 1473 for sharing free space information between vehicles 30 and 31, which are primary response vehicles, and vehicle 29 is the same as the operation shown in FIG. 29 . By receiving the conflict message 1474, vehicles 32 and 33, which are secondary response vehicles, recognize that they need to share their free space information, and perform communication 1475 for sharing free space information between vehicles 32 and 33 and vehicle 29. When the conflict is resolved through communication 1475, vehicle 29 broadcasts a resolution message 1476 to notify surrounding vehicles that the conflict in sharing free space information has been resolved.

[0121] In this way, by setting a secondary response vehicle in advance in discovery, a vehicle can quickly share free space information a second time even if a conflict occurs in the first sharing of free space information. Although messages such as notification messages, request messages, response messages, result messages, conflict messages, and resolution messages are transmitted by broadcast, if the destination is determined, the vehicle may transmit the message by unicast communication or groupcast communication.

[0122] Embodiment 20. In the above-described embodiment 19, conflicts are resolved by setting up to secondary response vehicles as response vehicles in the event of a conflict. However, if the conflict cannot be resolved even with the secondary response vehicles and information on more vehicles is required, the number of response vehicles may be increased to include tertiary and quaternary response vehicles. For example, it is possible to set up to Nth-order response vehicles. The result message 1472 shown in FIG. 30 includes information on up to the Nth-order response vehicles, and each vehicle recognizes its own order of response. The conflict message 1474 includes content requesting the nth-order response vehicle to provide free space information. Furthermore, the resolution message 1476 includes content indicating that response vehicles mth and subsequent orders do not need to provide free space information to vehicle 29. Note that N is an integer equal to or greater than 2, n is an integer equal to or greater than 2 and equal to or less than N, and m is an integer equal to or greater than 2, greater than n, and equal to or less than N.

[0123] In this way, by being able to flexibly change the degree of response, if a vehicle predicts from the capabilities included in a response message from a surrounding vehicle that it may not be possible to obtain information with the desired reliability by sharing the free space information only once, the vehicle can improve the reliability of the free space information by sharing the free space information multiple times, and perform these processes quickly. Note that, although messages such as notification messages, request messages, response messages, result messages, conflict messages, and resolution messages are transmitted by broadcast, if the destination is determined, the vehicle may transmit the messages by unicast communication or groupcast communication.

[0124] Embodiment 21 In the above-described embodiment 19 and embodiment 20, the primary and secondary response vehicles are actively performed by vehicles that wish to obtain free space information, but this may also be performed passively.

[0125] FIG. 31 is a sequence diagram showing the operation of passively selecting a vehicle that will quickly provide new free space information when a conflict occurs during the sharing of free space information in vehicles according to embodiment 21. In FIG. 31 , vehicle 29 is a vehicle that wishes to acquire free space information, and it is assumed that vehicles 30 to 33 among vehicles 30 to 34 are capable of providing free space information. Vehicles 30 to 33 broadcast a notification message 1480 including capabilities related to their own free space information. Vehicle 29 receives the notification message 1480 transmitted by vehicles 30 to 33, determines a primary response vehicle and a secondary response vehicle based on the free space information it wishes to acquire, and notifies vehicles 30 to 33 by broadcasting a result message 1481 indicating the determined primary response vehicle and secondary response vehicle. Here, it is assumed that vehicles 30 and 31 are primary response vehicles, and vehicles 32 and 33 are secondary response vehicles. Vehicles 30 and 31 that have received result message 1481 recognize that they are the primary response vehicles, and perform communication 1482 for sharing free space information between vehicles 30 and 31 and vehicle 29. If no conflict occurs here, vehicle 29 broadcasts resolution message 1485.

[0126] On the other hand, if a conflict occurs, vehicle 29 transmits conflict message 1483 and requests information from vehicles 32 and 33, which are secondary response vehicles. Vehicles 32 and 33 that receive conflict message 1483 perform communication 1484 for sharing free space information between vehicles 32 and 33 and vehicle 29. If the conflict is resolved by communication 1484, vehicle 29 broadcasts resolution message 1485 to notify that the conflict has been resolved.

[0127] The number of responding vehicles may be up to Nth responding vehicle. Furthermore, although the transmission of messages such as notification messages, request messages, response messages, result messages, conflict messages, and resolution messages is considered to be broadcast, they may be transmitted by unicast or groupcast communication if the destination is determined.

[0128] Taking into account the contents of embodiments 18 to 21, and explaining using the communication device 101 shown in Figure 1, it can be said that the wireless communication unit 104 actively or passively searches for the capabilities of the second free space information that it wishes to acquire, receives the second free space information that it wishes to acquire, and if a conflict occurs between the first free space information and the second free space information in the analysis of the free space information sharing unit 103, it can receive the second free space information from the communication device 201 at least once and transmit the first free space information to the communication device 201.

[0129] Embodiment 22 In the above-described Embodiments 19 to 21, the wireless communication method of the wireless communication unit is not particularly limited when setting the primary response vehicle, secondary response vehicle, etc. in the event of a conflict. However, the vehicle may use, as the wireless communication unit, a C-V2X communication unit capable of C-V2X communication, which is being standardized by 3GPP.

[0130] 32 is a sequence diagram showing the operation when a C-V2X communication unit is used when setting a primary response vehicle, a secondary response vehicle, etc. in the event of a conflict occurring when sharing free space information in a vehicle according to embodiment 22. In FIG. 32, vehicle 29 is a vehicle that desires to acquire free space information, and of vehicles 30 to 34, vehicles 30 to 33 are vehicles that can provide free space information. The communication devices mounted on each vehicle are the same as the communication devices 301 and 401 shown in FIG. 17 described in embodiment 10. Model B Discovery in ProSe Direct Discovery is used for discovery, and vehicle 29 broadcasts a Solicitation message 1490. In 3GPP standardization, this Solicitation message 1490 includes a Type of Discovery Message, a ProSe Application Code, a ProSe Restricted Code, a Relay Indication, a Security protection element, etc. For example, by providing a code for sharing free space information in one of the ProSe Application Code, the ProSe Restricted Code, etc., it is possible to clearly indicate that the vehicle 29 wishes to acquire free space information.

[0131] The vehicles 30 to 33 that have received the Solicitation message 1490 transmit a Response message 1491. In 3GPP standardization, the Response message 1491 includes a Type of Discovery Message, a ProSe Response Code, a relay indication, a security protection element, etc. Capabilities related to free space information may be included in various fields. For example, by providing a code for sharing free space information in one of the ProSe Response Codes, it is possible to clearly indicate that the vehicle 29 is capable of providing free space information. It may also be included in a metadata field that is prepared in addition to various other fields, and the available free space information may be expressed by a combination of these.

[0132] Vehicle 29, which has received Response message 1491, recognizes that vehicles 30 to 33 can provide free space information and notifies them by Result message 1492 that the primary and secondary response vehicles have been determined. This Result message 1492 may be a signal specified by 3GPP or a newly specified signal. If the signal is a newly specified signal, the primary and secondary response vehicles are specified by including the Layer-2 IDs of the primary and secondary response vehicles from the information obtained by Response message 1491. The Destination Layer-2 ID specifies the Layer-2 IDs of the primary and secondary response vehicles, or specifies the Layer-2 ID specified at the time of broadcasting.

[0133] Vehicles 30 and 31, which are primary response vehicles that received Result message 1492, share free space information with vehicle 29 via ProSe Direct Communication 1493. If no conflict exists, vehicle 29 notifies vehicle 29 that the conflict has been resolved via Resolution message 1496. This Resolution message 1496 may be a signal specified in 3GPP or a newly specified signal. If the signal is a newly specified signal, the Destination Layer-2 ID specifies the Layer-2 ID of the secondary response vehicle or the Layer-2 ID specified at the time of broadcast.

[0134] On the other hand, if the conflict is not resolved, vehicle 29 notifies vehicle 29 of the occurrence of the conflict by using Conflict message 1494. Vehicles 32 and 33 that have received Conflict message 1494 share free space information between vehicle 32 and vehicle 33 and vehicle 29 by using ProSe Direct Communication 1495. Conflict message 1494 may be a signal specified in 3GPP or may be a newly specified signal. If the signal is a newly specified signal, the Destination Layer-2 ID specifies the Layer-2 ID of the secondary responding vehicle or the Layer-2 ID specified at the time of broadcasting. When the contention is resolved by ProSe Direct Communication 1495, vehicle 29 notifies that the contention has been resolved by using Resolution message 1496. Resolution message 1496 may be a signal specified by 3GPP or a newly specified signal. If the signal is a newly specified signal, the Destination Layer-2 ID specifies the Layer-2 ID specified at the time of broadcasting.

[0135] In addition, a response vehicle of a second or higher order may be set. When the Conflict message 1494 is a newly defined signal, if the vehicle that has shared free space information up to that point is an (n-1)th order response vehicle, the Destination Layer-2 ID is specified as the Layer-2 ID of the nth or higher order response vehicle, or the Layer-2 ID associated with a group member when grouping them, or the Layer-2 ID specified at the time of broadcasting.

[0136] Taking the content of the 22nd embodiment into consideration, to explain using the communication device 301 shown in FIG. 17 , it can be said that the C-V2X communication unit 304 actively or passively searches for the capability of the second free space information that it wishes to acquire by ProSe Direct Discovery, receives the second free space information that it wishes to acquire by ProSe Direct Communication, and when a conflict occurs between the first free space information and the second free space information in the analysis of the free space information sharing unit 303, receives the second free space information from the communication device 401 by ProSe Direct Communication one or more times and transmits the first free space information to the communication device 401.

[0137] Embodiment 23. In the above-described embodiments 1 to 22, all vehicles that share free space information have their own absolute position information or relative position information, but if a vehicle that shares free space information does not have its own absolute position information or relative position information, a nearby vehicle may estimate the absolute position information or relative position information of that vehicle. Hereinafter, the ability of a vehicle to estimate and calculate the absolute position information or relative position information of another vehicle will be referred to as "positioning capability."

[0138] FIG. 33 is a sequence diagram showing the operation of a vehicle according to embodiment 23 when a nearby vehicle estimates the absolute position information or relative position information of a vehicle that shares free space information and does not have the absolute position information or relative position information of the vehicle itself. In FIG. 33, there are four vehicles, vehicles 40 to 43. In FIG. 33, there are four vehicles, vehicles 40 to 43. Vehicle 40 is a vehicle that can provide free space information but does not have the absolute position information or relative position information of the vehicle itself. Vehicle 41 is a vehicle that can calculate the absolute position information or relative position information of vehicle 40. Vehicle 42 is a vehicle that wishes to obtain free space information. The communication devices installed in each vehicle are the same as the communication devices 101 and 201 shown in FIG. 1 and described in embodiment 1.

[0139] Each vehicle broadcasts a notification message 1500 including a capability for free space information. At this time, vehicle 40 indicates in the notification message, in addition to the capability for free space information, that it does not possess absolute or relative position information of the vehicle. Vehicle 41 also indicates a capability for positioning vehicle 40 in addition to the capability for free space information. By receiving the notification message 1500, vehicle 42 recognizes that vehicle 40 possesses the free space information it wishes to acquire, but does not possess absolute or relative position information of its own vehicle, and that vehicle 41 possesses the capability for positioning vehicle 40. As a result, vehicle 42 recognizes that if vehicle 41 can calculate the absolute or relative position information of vehicle 40, it can utilize the free space information possessed by vehicle 40.

[0140] Therefore, first, vehicle 42 performs communication 1501 for sharing free space information between vehicle 42 and vehicle 40. Next, vehicle 42 transmits a positioning request message 1502 to vehicle 41, inquiring of vehicle 41 about absolute position information or relative position information of vehicle 40. Vehicle 41, having received the positioning request message 1502, acquires the absolute position information or relative position information of vehicle 40 using a positioning message 1503. Thereafter, vehicle 41 shares the absolute position information or relative position information of vehicle 40 with vehicle 42 using a positioning result sharing message 1504. Note that the order of sharing free space information and positioning may be reversed, and the transmission and reception of the positioning request message 1502, positioning message 1503, and positioning result sharing message 1504 may be performed before communication 1501 for sharing free space information.

[0141] In this way, even if there is a vehicle that shares free space information and does not have its own absolute position information or relative position information, by combining positioning by other vehicles, it is possible to utilize the free space information of the vehicle that does not have its own absolute position information or relative position information. For example, even if there is a vehicle that cannot obtain its own absolute position information in a place where it is difficult to receive GPS signals, such as inside a tunnel, it is possible to utilize the free space information with the assistance of such surrounding vehicles.

[0142] Embodiment 24 In the above-described embodiment 23, when a nearby vehicle estimates absolute position information or relative position information of another vehicle, a vehicle that desires to acquire free space information actively issues a request for positioning, but a vehicle capable of positioning may also passively obtain a positioning result by voluntarily performing positioning.

[0143] FIG. 34 is a sequence diagram showing the operation of vehicles according to embodiment 24 when a vehicle capable of positioning voluntarily performs positioning, and a vehicle desiring to acquire free space information passively obtains the positioning results. As in embodiment 23, each vehicle broadcasts a notification message 1500. By transmitting and receiving the notification message 1500, vehicle 40 and vehicle 42 perform communication 1501 for sharing free space information. Meanwhile, vehicle 41, upon receiving the notification message 1500, detects that vehicle 40 does not possess absolute position information or relative position information of its own vehicle, and recognizes that it is capable of positioning vehicle 40. Therefore, vehicle 41 estimates the absolute position information or relative position information of vehicle 40 using a positioning message 1503 and shares it with vehicle 42 using a positioning result sharing message 1504. The order of sharing free space information and positioning may be reversed, and the sending and receiving of positioning message 1503 and positioning result sharing message 1504 may be performed before communication 1501 for sharing free space information.

[0144] In this way, by having vehicles capable of positioning autonomously perform positioning, it is possible to reduce messages for requesting positioning.

[0145] Embodiment 25. In the above-described embodiments 23 and 24, the absolute position information or relative position information of a vehicle that does not have the absolute position information or relative position information of the host vehicle is estimated by one of the surrounding vehicles, but the absolute position information or relative position information of a vehicle that does not have the absolute position information or relative position information of the host vehicle may be estimated by multiple vehicles. Also, the absolute position information or relative position information of multiple vehicles that do not have the absolute position information or relative position information of the host vehicle may be estimated by one or multiple vehicles. Furthermore, free space information may be shared by multiple vehicles.

[0146] Embodiment 26 In the above-described embodiments 23 to 25, when vehicles that share free space information do not have absolute position information or relative position information of their own vehicles and surrounding vehicles estimate the absolute position information or relative position information of the vehicles, the sharing of free space information is performed passively, but the sharing of free space information may also be performed actively by a vehicle that wishes to obtain free space information.

[0147] FIG. 35 is a sequence diagram showing the operation of a vehicle according to embodiment 26, in which a nearby vehicle estimates the absolute or relative position information of a vehicle that shares free space information and actively shares the free space information when the vehicle does not possess the absolute or relative position information of the vehicle itself. In FIG. 35, there are four vehicles, vehicles 44 to 47. In FIG. 35, there are four vehicles, vehicles 44 to 47. Vehicle 46 is a vehicle that wishes to obtain free space information, vehicle 44 is a vehicle that can provide free space information but does not possess the absolute or relative position information of the vehicle itself, and vehicle 45 is a vehicle that can estimate the absolute or relative position information of vehicle 44. The communication devices installed in each vehicle are the same as the communication devices 101 and 201 shown in FIG. 1 and described in embodiment 1.

[0148] The vehicle 46 transmits a request message 1600 including a capability for the free space information it wishes to obtain. The vehicle 44, which has received the request message 1600, transmits a response message 1601 including information indicating that it can provide free space information but does not possess absolute or relative position information of its own vehicle. The vehicle 45 also transmits a response message 1602 indicating that it can estimate the absolute or relative position information of the vehicle 44. The vehicle 46 receives the response message 1601, recognizes that the vehicle 44 can provide the desired free space information, and performs communication 1603 for sharing the free space information between the vehicle 46 and the vehicle 44. The vehicle 46 also receives the response message 1602, recognizes that the vehicle 45 can estimate the absolute or relative position information of the vehicle 44, and transmits a positioning request message 1604 to the vehicle 45. Vehicle 45, which has received the positioning request message 1604, estimates the absolute position information or relative position information of vehicle 44 using a positioning message 1605, and shares the estimation result with vehicle 46 using a positioning result sharing message 1606. Note that the order of sharing free space information and positioning may be reversed, and the positioning request message 1604, positioning message 1605, and positioning result sharing message 1606 may be sent and received before communication 1603 for sharing free space information.

[0149] In this way, by actively sending and receiving messages, the vehicles can share free space information and positioning results with fewer messages.

[0150] Embodiment 27 In the above-described embodiment 26, when a vehicle that desires to acquire free space information actively performs discovery, surrounding vehicles actively estimate absolute position information or relative position information of vehicles that do not have the absolute position information or relative position information of the own vehicle, but the estimation of absolute position information or relative position information may also be passive.

[0151] 36 is a sequence diagram showing the operation of a vehicle according to embodiment 27 in which, when a vehicle desiring to acquire free space information actively performs discovery, a surrounding vehicle passively estimates the absolute position information or relative position information of a vehicle that does not possess its own absolute position information or relative position information. In FIG. 36, the process up to communication 1603 for sharing free space information is the same as in embodiment 26. Vehicle 45 receives a response message 1601 from vehicle 44 to vehicle 46, or more precisely, by overhearing, vehicle 45 recognizes that vehicle 44 does not possess its own absolute position information or relative position information, estimates the absolute position information or relative position information of vehicle 44 by a positioning message 1605, and shares the result with vehicle 46 by a positioning result sharing message 1606.

[0152] In this way, the vehicle can reduce the number of positioning request messages by passively performing positioning.

[0153] Taking the contents of the twenty-third to twenty-seventh embodiments into consideration, and using the communication device 101 shown in FIG. 1 as an explanation, it can be said that the wireless communication unit 104 actively or passively searches for the capability of the second free space information desired to be acquired, receives the second free space information desired to be acquired, and, if the vehicle 2 does not have the location information of the vehicle 2, can acquire the location information of the vehicle 2 from a third vehicle that can measure the location information of the vehicle 2. In the cases of the twenty-third and twenty-fourth embodiments, the first vehicle is the vehicle 42, the second vehicle is the vehicle 40, and the third vehicle is the vehicle 41. In the cases of the twenty-sixth and twenty-seventh embodiments, the first vehicle is the vehicle 46, the second vehicle is the vehicle 44, and the third vehicle is the vehicle 45.

[0154] Embodiment 28. In the above-described embodiments 23 to 27, a vehicle sharing free space information does not possess absolute position information or relative position information of its own vehicle, and when a surrounding vehicle estimates the absolute position information or relative position information of the vehicle, the estimation method is not particularly limited. In embodiment 28, the estimation method may be performed using Ranging / SL Positioning, which is standardized by 3GPP. As described in "3GPP TS 23.586 V18.1.0 "Ranging-based services and Sidelink Positioning", 3GPP has standardized a positioning and ranging technique using direct communication between terminals, i.e., a sidelink. Hereinafter, the positioning and ranging technique using a sidelink in 3GPP is referred to as Ranging / SL Positioning. In Ranging / SL Positioning, information such as distance, position, and speed can be obtained as positioning and ranging results through sidelink communication between terminals.

[0155] 37 is a sequence diagram showing the operation of a vehicle according to embodiment 28 that shares free space information, but does not possess absolute or relative position information of its own vehicle, and a surrounding vehicle estimates the vehicle's absolute or relative position information by Ranging / SL Positioning. In FIG. 37, there are four vehicles, vehicles 48 to 51. In FIG. 37, there are four vehicles, vehicles 48 to 51. Vehicle 50 is a vehicle that wishes to acquire free space information, vehicle 48 is a vehicle that can provide free space information but does not possess absolute or relative position information of its own vehicle, and vehicle 49 is a vehicle that can estimate the absolute or relative position information of vehicle 48 by Ranging / SL Positioning. Here, from the viewpoint of Ranging / SL Positioning, vehicle 50 is an SL Positioning Client UE, vehicle 48 is a Target UE, and vehicle 49 is an SL Reference UE or Located UE. The communication devices mounted on each vehicle are the same as the communication devices 301 and 401 shown in FIG. 17 and described in the tenth embodiment.

[0156] Each vehicle broadcasts its own capability for free space information by transmitting an announcement message 1700. Furthermore, vehicle 49 broadcasts its positioning capability by broadcasting a Ranging / SL Positioning Announcement message 1701. In 3GPP standardization, the Ranging / SL Positioning Announcement message 1701 includes a Type of Discovery Message, a Security protection element, RSPP metadata information, and the User Info ID of vehicle 49.

[0157] Upon receiving the announcement message 1700 from the vehicle 48, the vehicle 50 performs communication 1702 for sharing free space information between the vehicle 50 and the vehicle 49. Furthermore, upon receiving the Ranging / SL Positioning Announcement message 1701 from the vehicle 49, the vehicle 48 and the vehicle 50 recognize that ranging / SL positioning by the vehicle 49 is possible. The vehicle 50, which is an SL Positioning Client UE, transmits a Ranging / SL Positioning service request 1703 to the vehicle 49, which is an SL Reference UE or Located UE. Vehicle 49 performs communication 1704 for ranging / SL positioning with vehicle 48, which is a target UE, and acquires location information of vehicle 48. Specifically, communication 1704 follows procedure 6.8 of the aforementioned "3GPP TS 23.586 V18.1.0 "Ranging based services and Sidelink Positioning". Vehicle 49 transmits the acquired location information to vehicle 50 by means of a Ranging / SL Positioning Response 1705.

[0158] In this way, by utilizing Ranging / SL Positioning, a vehicle can acquire and estimate absolute position information or relative position information of a vehicle that does not have its own absolute position information or relative position information, through positioning and ranging using sidelink communication.

[0159] Embodiment 29 In the above-described embodiment 28, when a vehicle that shares free space information does not have absolute position information or relative position information of its own vehicle and a surrounding vehicle estimates the absolute position information or relative position information of that vehicle by ranging / SL positioning, discovery of the vehicle that performs ranging / SL positioning is passively performed, but this may also be performed actively.

[0160] 38 is a sequence diagram showing the operation of vehicles according to embodiment 29 when vehicles that share free space information do not possess absolute position information or relative position information of their own vehicle and surrounding vehicles estimate the absolute position information or relative position information of the vehicle by ranging / SL positioning, and when actively discovering vehicles that perform ranging / SL positioning. In FIG. 38, vehicle 50 is a vehicle that wishes to acquire free space information, vehicle 48 is a vehicle that can provide free space information but does not possess absolute position information or relative position information of its own vehicle, and vehicle 49 is a vehicle that can estimate the absolute position information or relative position information of vehicle 48 by ranging / SL positioning. Here, from the viewpoint of Ranging / SL Positioning, vehicle 50 is an SL Positioning Client UE, vehicle 48 is a Target UE, and vehicle 49 is an SL Reference UE or Located UE.

[0161] Each vehicle transmits a notification message 1800 to broadcast its own capability regarding free space information. By receiving the notification message from vehicle 48, vehicle 50 recognizes that vehicle 48 is a terminal capable of providing free space information, but does not possess absolute or relative vehicle position information. Therefore, vehicle 50 transmits a Ranging / SL Positioning Solicitation message 1801. Vehicles 48 and 49 that have received Ranging / SL Positioning Solicitation message 1801 transmit Ranging / SL Positioning Response message 1802 in response, since vehicle 48 is the Target UE and vehicle 49 is the SL Reference UE or Located UE. In 3GPP standardization, the Ranging / SL Positioning Response message 1802 includes a Type of Discovery Message, a Security protection element, its own User Info ID, Target Info, the User Info ID of vehicle 48 or vehicle 49, RSPP metadata information, and the like.

[0162] Upon receiving the Ranging / SL Positioning Response message 1802, the vehicle 50 recognizes that the position information of the vehicle 48 can be acquired by the vehicle 49. By receiving the notification message 1800 from the vehicle 48, the vehicle 50 performs communication 1803 for sharing free space information between the vehicle 50 and the vehicle 48. The vehicle 50, which is an SL Positioning Client UE, transmits a Ranging / SL Positioning service request 1804 to the vehicle 49, which is an SL Reference UE or Located UE. The vehicle 49 performs communication 1805 for Ranging / SL Positioning with the vehicle 48, which is a Target UE, and acquires the position information of the vehicle 48. Specifically, the communication 1805 follows the procedure of 6.8 of the aforementioned "3GPP TS 23.586 V18.1.0 "Ranging based services and Sidelink Positioning". The vehicle 49 transmits the acquired position information to the vehicle 50 by a Ranging / SL Positioning Response 1806.

[0163] 17 , based on the contents of the twenty-eighth to twenty-ninth embodiments, the C-V2X communication unit 304 actively or passively searches for the capability of the second free space information desired to be acquired, receives the second free space information desired to be acquired, and if the vehicle 16 does not have the position information of the vehicle 16, a third vehicle capable of determining the position information of the vehicle 16 determines the position information of the vehicle 16 by ranging / SL positioning, and can acquire the position information of the vehicle 16 from the third vehicle. In the twenty-eighth and twenty-ninth embodiments, the first vehicle is the vehicle 50, the second vehicle is the vehicle 48, and the third vehicle is the vehicle 49.

[0164] Embodiment 30. In the above-described embodiment 29, when a vehicle that shares free space information does not have its own absolute position information or relative position information and a surrounding vehicle estimates the vehicle's absolute position information or relative position information by ranging / SL positioning, the vehicle performs discovery of the vehicle that performs ranging / SL positioning independently. However, when a vehicle group is determined in advance and ranging / SL positioning is performed using the vehicle group, the Group Member Discovery method described in 6.4.2.2 of the aforementioned "3GPP TS 23.586 V18.1.0 "Ranging based services and Sidelink Positioning"" may be used.

[0165] Embodiment 31. In the above-described embodiment 29, discovery of capabilities when sharing free space information and discovery for acquiring location information are performed independently, but these may be performed simultaneously. For example, the respective notification messages, response messages, request messages, etc. in discovery of capabilities when sharing free space information and discovery for acquiring location information may be combined. Furthermore, when ProSe Direct Discovery and ProSe Direct Communication are used with Ranging / SL Positioning, discovery in Ranging / SL Positioning follows ProSe Direct Discovery, and therefore these may be merged by integrating fields such as an Announcement message, a Solicitation message, and a Response message.

[0166] 17 , the C-V2X communication unit 304 actively or passively searches for the capability of the second free space information that the C-V2X desires to acquire, receives the second free space information that the C-V2X desires to acquire, and, if the C-V2X communication unit 304 does not possess the location information of the vehicle 16, when acquiring the location information of the vehicle 16 from a third vehicle that can determine the location information of the vehicle 16, the C-V2X communication unit 304 can simultaneously search for the capability of the second free space information and the capability of positioning the vehicle 16. In the case of the 31st embodiment, taking the example of the 29th embodiment, the first vehicle is the vehicle 50, the second vehicle is the vehicle 48, and the third vehicle is the vehicle 49.

[0167] Embodiment 32 In the above-described embodiments 1 to 31, the free space information is defined as including absolute position information or relative position information, but the free space information may also include information such as vehicle speed, vehicle movement direction, and time.

[0168] FIG. 39 is a diagram showing an example in which free space information in a vehicle according to embodiment 32 includes information such as vehicle speed, vehicle movement direction, and time. Free space information 2000 includes vehicle movement direction 2002, vehicle movement speed 2003, and the like, in addition to absolute or relative position information 2001 of the vehicle itself, and also includes time information 2004 and a flag 2005 for the free space information. The time information 2004 for the free space information indicates that the free space information is free space information at that time. Therefore, for example, the time information may not only be the time at the moment the free space information is acquired, but may also be a past time if the free space information is past free space information, or a future time if the free space information is a prediction of future free space information. In this case, the flag 2005 can be used to indicate whether the free space information is past, present, or future free space information.

[0169] In this way, by including information such as vehicle speed, vehicle direction of movement, and time in the free space information, the vehicle can treat the free space information of a moving vehicle, which changes from moment to moment, as time-series data, and can also treat it as data that takes into account changes in the moving speed, direction of movement, etc.

[0170] Embodiment 33 In the above-described embodiments 3 to 32, when discovering the capability of free space information, the area range in which free space information can be provided is specified, but information such as vehicle speed, vehicle movement direction, and time may also be specified.

[0171] For example, the capability of free space information is discovered in the following ways: indicating that one wishes to obtain free space information at a certain time; indicating that one wishes to obtain future or past free space information such as N seconds from now or M seconds ago; indicating that one wishes to obtain free space information for a vehicle moving at a certain vehicle speed; or indicating that one wishes to obtain free space information for a vehicle moving in a certain direction.

[0172] In this way, by performing discovery based on information contained in the free space information, such as vehicle speed, vehicle direction of movement, and time, vehicles can more flexibly acquire and utilize their free space information, which changes from moment to moment.

[0173] Embodiment 34. In the above-described embodiments 1 to 33, free space information is shared between vehicles, but the entity that shares the free space information does not have to be limited to vehicles. For example, any entity that has a function to realize at least one of the above-described embodiments 1 to 33 may be a pedestrian, a robot, a drone or other mobility, a roadside unit, a building, or the like.

[0174] The configurations shown in the above embodiments are merely examples, and may be combined with other known technologies, or different embodiments may be combined with each other. It is also possible to omit or modify parts of the configurations as long as they do not deviate from the gist of the invention.

[0175] 1 to 34, 40 to 51 Vehicles, 70, 70a Communication system, 90, 93 Processing circuit, 91 Processor, 92 Memory, 100, 200, 300, 400 Application execution unit, 101, 201, 301, 401, 501, 601, 701, 801 Communication device, 102, 105, 132, 202, 205, 302, 305, 402, 405, 900 Interface, 103, 203, 303, 403 Free space information sharing unit, 104, 204 Wireless communication unit, 130 Free space information generation unit, 131 Free space information analysis unit, 133 Self-location information collection unit, 134 Other location information collection unit, 304, 404 C-V2X communication unit, 910 PC5 interface.

Claims

1. A communication device mounted on a vehicle, comprising: a free space information sharing unit that collects self-location information, which is vehicle location information of the vehicle, and other-party location information, which includes vehicle location information of other vehicles and location information of obstacles, and generates self-vehicle free space information, which is free space information indicating locations where the vehicle, the other vehicles, or the obstacles are not present; and a communication unit that receives other-vehicle free space information, which is free space information generated by the other vehicles, and transmits the self-vehicle free space information to the other vehicles.

2. The communication device according to claim 1, wherein the free space information sharing unit shares the subject vehicle free space information and the other vehicle free space information with the other vehicles.

3. The communication device described in claim 1 or 2, characterized in that the accuracy and granularity of the free space information that each vehicle can provide is defined as a capability, and the communication unit actively or passively searches for the capability of the other vehicle free space information that the vehicle wishes to obtain, and receives the other vehicle free space information that the vehicle wishes to obtain.

4. The communication device according to claim 1 or 2, characterized in that the accuracy and granularity of the free space information that each vehicle can provide is defined as a capability, and the communication unit actively or passively searches for the capability of the other vehicle free space information that the vehicle wishes to acquire by using ProSe Direct Discovery, and receives the other vehicle free space information that the vehicle wishes to acquire by using ProSe Direct Communication.

5. The communication device according to claim 1 or 2, characterized in that the accuracy and granularity of the free space information that each vehicle can provide is defined as a capability, and the communication unit actively or passively searches for the capability of the other vehicle free space information that the vehicle wishes to acquire by using ProSe UE-to-UE Relay Discovery, and receives the other vehicle free space information that the vehicle wishes to acquire by using multi-hop ProSe Direct Communication.

6. The communication device described in claim 1 or 2, characterized in that the accuracy and granularity of the free space information that each vehicle can provide is defined as a capability, the communication unit actively or passively searches for the capability of the other vehicle free space information that the vehicle wishes to acquire, receives the other vehicle free space information that the vehicle wishes to acquire, and if a conflict occurs between the vehicle's own vehicle free space information and the other vehicle free space information in the analysis of the free space information sharing unit, receives the other vehicle free space information from the other vehicle at least once and transmits the vehicle's own vehicle free space information to the other vehicle.

7. The communication device according to claim 1 or 2, characterized in that the accuracy and granularity of the free space information that each vehicle can provide are defined as capabilities, and the communication unit actively or passively searches for the capabilities of the other-vehicle free space information that each vehicle wishes to acquire using ProSe Direct Discovery, receives the other-vehicle free space information that each vehicle wishes to acquire using ProSe Direct Communication, and when a conflict occurs between the host vehicle free space information and the other-vehicle free space information in the analysis of the free space information sharing unit, receives the other-vehicle free space information from the other vehicle using ProSe Direct Communication one or more times and transmits the host vehicle free space information to the other vehicle.

8. The communication device described in claim 1 or 2, characterized in that the accuracy and granularity of the free space information that each vehicle can provide is defined as a capability, and the communication unit actively or passively searches for the capability of the other vehicle free space information that the vehicle wishes to obtain, receives the other vehicle free space information that the vehicle wishes to obtain, and if the other vehicle does not have the location information of the other vehicle, obtains the location information of the other vehicle from a vehicle that is capable of determining the location information of the other vehicle.

9. The communication device according to claim 1 or 2, characterized in that the accuracy and granularity of the free space information that each vehicle can provide is defined as a capability, the communication unit actively or passively searches for the capability of the other vehicle free space information that each vehicle wishes to acquire, receives the other vehicle free space information that each vehicle wishes to acquire, and if the other vehicle does not have the location information of the other vehicle, a vehicle capable of determining the location information of the other vehicle determines the location information of the other vehicle by ranging / SL positioning, and acquires the location information of the other vehicle from the vehicle capable of determining the location information of the other vehicle.

10. The communication device described in claim 1 or 2, characterized in that the accuracy and granularity of the free space information that each vehicle can provide is defined as a capability, and the communication unit actively or passively searches for the capability of the other vehicle free space information that the vehicle wishes to acquire, receives the other vehicle free space information that the vehicle wishes to acquire, and if the other vehicle does not have the location information of the other vehicle, when acquiring the location information of the other vehicle from a vehicle that is capable of determining the location information of the other vehicle, simultaneously searches for the capability of the other vehicle free space information and the capability of determining the location of the other vehicle.

11. A communication system comprising a first communication device mounted on a first vehicle and a second communication device mounted on a second vehicle, wherein the first communication device comprises: a first free space information sharing unit that collects self-location information, which is vehicle location information of the first vehicle, and other party location information, which includes vehicle location information of other vehicles and location information of obstacles, and generates first free space information, which is free space information indicating a location where the first vehicle, the other vehicles, or the obstacles are not present; a first communication unit that receives second free space information, which is free space information indicating a location where the second vehicle, the other vehicles, or the obstacles are not present, transmitted from the second communication device, and transmits the first free space information to the second communication device; and the second communication device comprises: a second free space information sharing unit that collects self-location information, which is vehicle location information of the second vehicle, and other party location information, which includes vehicle location information of other vehicles and location information of obstacles, and generates the second free space information. a second communication unit that receives the first free space information transmitted from the first communication device and transmits the second free space information to the first communication device.

12. A control circuit for controlling a communication device mounted on a vehicle, characterized in that the control circuit causes the communication device to perform the following: collect self-position information, which is vehicle position information of the vehicle, and other-party position information, which includes vehicle position information of other vehicles and position information of obstacles; generate self-vehicle free space information, which is free space information indicating locations where the vehicle, the other vehicles, or the obstacles are not present; receive other-vehicle free space information, which is free space information generated by the other vehicles; and transmit the self-vehicle free space information to the other vehicles.

13. A storage medium storing a program for controlling a communication device mounted on a vehicle, the program causing the communication device to perform the following: collect self-location information, which is vehicle location information of the vehicle, and other-party location information, which includes vehicle location information of other vehicles and location information of obstacles; generate self-vehicle free space information, which is free space information indicating locations where the vehicle, the other vehicles, or the obstacles are not present; receive other-vehicle free space information, which is free space information generated by the other vehicles; and transmit the self-vehicle free space information to the other vehicles.

14. A communication method for a communication device mounted on a vehicle, comprising: a free space information generation step in which a free space information sharing unit collects self-location information, which is vehicle location information of the vehicle, and other-party location information, which includes vehicle location information of other vehicles and location information of obstacles, and generates self-vehicle free space information, which is free space information indicating a location where the vehicle, the other vehicles, or the obstacles are not present; and a communication step in which a communication unit receives other-vehicle free space information, which is free space information generated by the other vehicles, and transmits the self-vehicle free space information to the other vehicles.

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