Communication device and communication method

Abstract

A target object information communication device provided with a target object information transmission unit (67) that wirelessly transmits target object information, which is information about a target object, the presence of which has been recognized, said target object information communication device being provided with: a message acquisition unit (64) that acquires free space information from another target object information communication device, which is mounted on a moving body; a target object characteristic estimation unit (65) that estimates target object characteristics about the target object, including relative distance and direction of movement; and a prediction unit (66) that predicts whether or not the target object will move into a space where the moving body can move, on the basis of the target object characteristics and the free space information. In a case where the prediction unit predicts that the target object will move into the space where the moving body can move, the target object information transmission unit (67) assigns higher priority to the transmission of the target object information about the target object than in a case where the prediction unit does not predict that the target object will move into the space where the moving body can move.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on Patent Application No. 2022-036587 filed in Japan on March 9, 2022, and the contents of the original application are incorporated by reference in their entirety. [Technical Field]

[0002] The present invention relates to a communication device and a communication method, and more particularly to a communication device and a communication method for notifying surrounding areas of the presence of a recognized target. [Background technology]

[0003] As disclosed in Patent Document 1, a communication device that transmits target information to the surrounding area is known. When another communication device receives this target information, the other communication device can recognize that a target exists outside the line of sight. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-79316 Summary of the Invention

[0005] The amount of information that a communication device that transmits target information can transmit at one time is limited. If there are many targets around the communication device that transmits target information, it may not be possible to transmit target information for all of the targets at once.

[0006] The present disclosure has been made based on this situation, and its purpose is to provide a communication device and a communication method that can transmit target information that is likely to be useful to a receiving device.

[0007] The above object is achieved by the combination of features recited in the independent claims, and the subclaims define further advantageous specific examples. The reference numerals in parentheses in the claims correspond to specific aspects described in the following embodiments as one aspect, and do not limit the technical scope of the disclosure.

[0008] One disclosure relating to a communication device to achieve the above object is: A communication device including a target information transmitting unit that wirelessly transmits target information, which is information on a target whose existence has been recognized, a free space information acquisition unit that acquires free space information from other communication devices mounted on the mobile object; a target characteristic estimation unit that estimates target characteristics including a relative distance and a moving direction of the target; a prediction unit that predicts whether the target will move into a space in which the moving body can move, based on the target characteristics and the free space information; The target information transmitting unit, when the predicting unit predicts that the target will move into a space in which the moving body can move, prioritizes transmitting target information about the target more highly than when the predicting unit does not predict that the target will move into a space in which the moving body can move. death, When the prediction unit predicts that the target will move into a space where the moving body can move for a plurality of combinations of the moving body and the target, the target information transmission unit compares the lengths in the road width direction of the spaces where the moving body can move, and assigns a higher priority to transmitting target information about a target moving into a space with a shorter length in the road width direction. It is a communication device. Another disclosure relating to a communication device for achieving the above object is: A communication device including a target information transmitting unit that wirelessly transmits target information, which is information on a target whose existence has been recognized, a free space information acquisition unit that acquires free space information from other communication devices mounted on the mobile object; a target characteristic estimation unit that estimates target characteristics including a relative distance and a moving direction of the target; a prediction unit that predicts whether the target will move into a space in which the moving body can move, based on the target characteristics and the free space information; the target information transmitting unit, when the prediction unit predicts that the target will move into the space in which the moving body can move, gives a higher priority to transmitting the target information about the target than when the prediction unit does not predict that the target will move into the space in which the moving body can move; When it is predicted that there are multiple targets moving in a space in which a moving body can move, the target information transmitting unit compares the lengths of the road width direction of the space in which the moving body can move if the collision time margins between the multiple targets and the moving body are at the same level, and increases the priority of transmitting target information for targets moving in spaces with shorter road width direction lengths, and increases the priority of transmitting target information for targets with shorter collision time margins than for targets with longer collision time margins if the collision time margins are not at the same level. Another disclosure relating to a communication device for achieving the above object is: A communication device including a target information transmitting unit that wirelessly transmits target information, which is information on a target whose existence has been recognized, a free space information acquisition unit that acquires free space information from other communication devices mounted on the mobile object; a target characteristic estimation unit that estimates target characteristics including a relative distance and a moving direction of the target; a prediction unit that predicts whether the target will move into a space in which the moving body can move, based on the target characteristics and the free space information; the target information transmitting unit, when the prediction unit predicts that the target will move into the space in which the moving body can move, gives a higher priority to transmitting the target information about the target than when the prediction unit does not predict that the target will move into the space in which the moving body can move; When the prediction unit predicts that the target will move into a space in which the moving body can move for a plurality of combinations of the moving body and the target, the target information transmission unit assigns a higher priority to a case in which the target and the moving body are on different roads than to a case in which the target and the moving body are on the same road; The target information transmission unit is a communication device that determines a priority based on whether the target and the moving object are on the same road or whether the target and the moving object are on different roads, and then, if there are multiple targets with the same priority, compares the lengths of the spaces in which the moving object can move in the road width direction, and increases the priority of transmitting target information for targets moving into spaces with shorter lengths in the road width direction.

[0009] This communication device includes a prediction unit that predicts whether the target will move into a space where the moving object can move, based on the target characteristics and the free space information. The target information transmission unit prioritizes transmitting target information about the target when the prediction unit predicts that the target will move into a space where the moving object can move, compared to when the prediction unit does not predict that the target will move into a space where the moving object can move. Therefore, if the target information communication device that transmitted the free space information is treated as a receiving device, it can transmit target information that is likely to be useful to the receiving device.

[0010] One disclosure relating to a communication method for achieving the above object is: A communication method for wirelessly transmitting target information, which is information on a target whose presence has been recognized, comprising: Acquiring free space information from a target information communication device mounted on a moving object; estimating target characteristics, including relative range and direction of movement, for the target; predicting whether the target will move into a space in which the moving object can move based on the target characteristics and free space information; If the target predicts that the moving object will move into a space where the moving object can move, the target information about the target is sent with a higher priority than if the target does not predict that the moving object will move into a space where the moving object can move. death, For multiple combinations of moving bodies and targets, when it is predicted that the target will move into a space where the moving body can move, the lengths of the spaces in the road width direction where the moving body can move are compared, and the priority of transmitting target information for targets moving into spaces with shorter lengths in the road width direction is increased. It is a method of communication. Another disclosure relating to a communication method for achieving the above object is: A communication method for wirelessly transmitting target information, which is information on a target whose presence has been recognized, comprising: Acquiring free space information from a target information communication device mounted on a moving object; estimating target characteristics for the target, including relative range and direction of movement; predicting whether the target will move into a space in which the moving object can move based on the target characteristics and free space information; When the target predicts that the moving object will move into the space in which the moving object can move, the target information for the target is given a higher priority than when the target does not predict that the moving object will move into the space in which the moving object can move; In this communication method, when a prediction unit predicts that there are multiple targets moving into a space in which a moving body can move, if the collision time margins between the multiple targets and the moving body are at the same level, the lengths of the road width direction of the space in which the moving body can move are compared, and the priority of transmitting target information about targets moving into spaces with shorter road width direction lengths is increased, and if the collision time margins are not at the same level, the priority of transmitting target information about targets with shorter collision time margins is increased over targets with longer collision time margins. Another disclosure relating to a communication method for achieving the above object is: A communication method for wirelessly transmitting target information, which is information on a target whose presence has been recognized, comprising: Acquiring free space information from a target information communication device mounted on a moving object; estimating target characteristics for the target, including relative range and direction of movement; predicting whether the target will move into a space in which the moving object can move based on the target characteristics and free space information; When the target predicts that the moving object will move into the space in which the moving object can move, the target information for the target is given a higher priority than when the target does not predict that the moving object will move into the space in which the moving object can move; For multiple combinations of moving bodies and targets, when it is predicted that the target will move into a space where the moving body can move, a case where the target and the moving body exist on different roads is given a higher priority than a case where the target and the moving body exist on the same road; This is a communication method in which, after determining the priority based on whether the target and the moving object are on the same road or on different roads, if there are multiple targets with the same priority, the lengths of the spaces in which the moving objects can move in the road width direction are compared, and a higher priority is given to transmitting target information for targets moving into spaces with shorter lengths in the road width direction. [Brief explanation of the drawings]

[0011] [Figure 1] 1 illustrates an example architecture of a V2X communication device. [Figure 2] FIG. 1 is a diagram illustrating a V2X message. [Figure 3] Diagram showing logical interfaces for CP services and other layers. [Figure 4] Functional block diagram of the CP service. [Figure 5] A diagram showing the basic format of CPM. [Figure 6] FIG. 10 is a diagram showing an example of OVC in CPM. [Figure 7] FIG. 1 is a diagram illustrating FOC (or SIC) in CPM. [Figure 8] FIG. 1 is a diagram illustrating POC in CPM. [Figure 9] A diagram illustrating the reliability of free space. [Figure 10] FIG. 10 is a diagram for explaining a sensor data extraction method. [Figure 11] FIG. 1 is a diagram illustrating a CP service. [Figure 12] Configuration diagram of an in-vehicle system including a V2X communication device. [Figure 13] FIG. 2 is a diagram illustrating an example of the positional relationship between the host vehicle, other vehicles, and a target. [Figure 14] FIG. 2 is a diagram illustrating an example of the positional relationship between the host vehicle, other vehicles, and a target. [Figure 15] FIG. 2 is a diagram illustrating an example of the positional relationship between the host vehicle, other vehicles, and a target. [Figure 16] 10 is an example of a flowchart illustrating a process for transmitting a CPM. [Figure 17] 8 is an example of a flowchart showing detailed processing of S3 in FIG. 7. [Figure 18]18 is an example of a flowchart showing a process executed subsequent to FIG. 17. [Figure 19] 8 is an example of a flowchart showing detailed processing of S4 in FIG. 7. [Figure 20] 8 is an example of a flowchart showing detailed processing of S6 in FIG. 7. [Figure 21] 21 is an example of a flowchart showing detailed processing of S69 in FIG. 20. [Figure 22] 22 is an example of a flowchart showing a process executed subsequent to FIG. 21. [Figure 23] 22 is a flowchart showing an example of detailed processing of S691 in FIG. 21. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, several embodiments will be described with reference to the drawings. Note that corresponding components in each embodiment are given the same reference numerals, and redundant description may be omitted. When only a portion of the configuration is described in each embodiment, the configuration of another embodiment described previously can be applied to the remaining portion of the configuration. Furthermore, in addition to the combinations of configurations explicitly stated in the description of each embodiment, configurations of several embodiments can also be partially combined together even if not explicitly stated, as long as there is no particular problem with the combination.

[0013] In one embodiment, the communication device for transmitting target information according to the present disclosure is mounted on a vehicle. When mounted on a vehicle, the communication device can also be called a V2X communication device. The V2X communication device may perform communication between vehicles, between a vehicle and infrastructure, between a vehicle and a bicycle, between a vehicle and a mobile terminal, and the like. The V2X communication device may correspond to an on-board device of a vehicle, or may be included in the on-board device. The on-board device may be called an OBU (On-Board Unit).

[0014] The communication device may correspond to a roadside unit of the infrastructure or may be included in the roadside unit. The roadside unit is sometimes called an RSU (Road Side Unit). The communication device may also be one element of an ITS (Intelligent Transport System). If the communication device is one element of the ITS, the communication device may correspond to an ITS station (ITS-S) or may be included in the ITS-S. The ITS-S is a device that exchanges information, and may be any of an OBU, an RSU, or a mobile terminal, or may be included in any of them. The mobile terminal is, for example, a PDA (Personal Digital Assistant) or a smartphone.

[0015] The communication device may correspond to a WAVE (Wireless Access in Vehicular) device disclosed in IEEE 1609, or may be included in a WAVE device.

[0016] In this embodiment, the communication device is a V2X communication device mounted on a vehicle. This V2X communication device has a function of providing a CP (Collective Perception) service. In the CP service, the V2X communication device transmits a CPM (Collective Perception Message). Note that even if the communication device is an RSU or a mobile terminal, the same or similar methods as those disclosed below can be applied.

[0017] 1 is a diagram illustrating an exemplary architecture of a V2X communication device according to an embodiment of the present disclosure. The architecture illustrated in FIG. 1 is based on the reference architecture of ITS-S in accordance with the EU standard. The architecture illustrated in FIG. 1 includes an application layer 110, a facility layer 120, a network and transport layer 140, an access layer 130, a management layer 150, and a security layer 160.

[0018] The application layer 110 implements or supports various applications 111. In Fig. 1, examples of the applications 111 include a traffic safety application 111a, an efficient traffic information application 111b, and other applications 111c.

[0019] The facility layer 120 supports the execution of various use cases defined in the application layer 110. The facility layer 120 can support functions that are the same as or similar to those of the top three layers (application layer, presentation layer, and session layer) in the OSI reference model. Note that facility means providing a function, information, or data. The facility layer 120 may provide the functions of a V2X communication device. For example, the facility layer 120 may provide the functions of application support 121, information support 122, and communication support 123 shown in FIG. 1.

[0020] The application support 121 has a function to support a basic set of applications or a set of messages. An example of a message is a V2X message. The V2X message can include periodic messages such as a Cooperative Awareness Message (CAM) and event messages such as a Decentralized Environmental Notification Message (DENM). The facility layer 120 can also support CPM.

[0021] The information support 122 has the function of providing common data or databases used for a basic application set or message set. One example of a database is a local dynamic map (LDM).

[0022] The communication support 123 has a function for providing services for communication and session management, such as address mode and session support.

[0023] In this manner, the facility layer 120 supports an application set or a message set, i.e., the facility layer 120 generates a message set or a message based on the information to be transmitted or the service to be provided by the application layer 110. The messages generated in this manner may be referred to as V2X messages.

[0024] The access layer 130 includes an external IF (Interface) 131 and an internal IF 132, and can transmit messages / data received by the upper layer via a physical channel. For example, the access layer 130 can perform or support data communication using the following communication technologies: communication technologies based on the IEEE 802.11 and / or 802.11p standards, ITS-G5 wireless communication technologies based on the physical transmission technologies of the IEEE 802.11 and / or 802.11p standards, 2G / 3G / 4G (LTE) / 5G wireless mobile communication technologies including satellite / broadband wireless mobile communications, wideband terrestrial digital broadcasting technologies such as DVB-T / T2 / ATC, GNSS communication technology, and WAVE communication technology.

[0025] The network and transport layer 140 can use various transport protocols and network protocols to configure a network for vehicle communication between homogeneous and heterogeneous networks. The transport layer is a connection layer between upper and lower layers. Upper layers include the session layer, presentation layer, and application layer 110. Lower layers include the network layer, data link layer, and physical layer. The transport layer can manage transmitted data to ensure it arrives at its destination correctly. At the sender side, the transport layer processes data into packets of appropriate size for efficient data transmission. At the receiver side, the transport layer restores the received packets to the original file. Transport protocols include, for example, TCP (Transmission Control Protocol), UDP (User Datagram Protocol), and BTP (Basic Transport Protocol).

[0026] The network layer can manage logical addresses. The network layer may also determine packet delivery routes. The network layer may receive packets generated in the transport layer and add destination logical addresses to network layer headers. Packet transmission routes may include unicast / multicast / broadcast between vehicles, between vehicles and fixed stations, and between fixed stations. Geo-networking, mobility support, or IPv6 networking related to geo-networking may be considered as network protocols.

[0027] As shown in Fig. 1, the architecture of the V2X communication device may further include a management layer 150 and a security layer 160. The management layer 150 manages data transmission and interaction between layers. The management layer 150 includes a management information base 151, a regulatory management 152, an inter-layer management 153, a station management 154, and an application management 155. The security layer 160 manages security for all layers. The security layer 160 includes a firewall and intrusion detection management 161, an authentication, authorization, and profile management 162, and a security management information base 163.

[0028] 2 shows an example of a V2X message. A V2X message may also be called an ITS message. A V2X message may be generated by the application layer 110 or the facility layer 120. Examples of V2X messages are CAM, DENM, and CPM.

[0029] The transport layer in the network and transport layer 140 generates a BTP packet. The network layer in the network and transport layer 140 can encapsulate the BTP packet to generate a geo-networking packet. The geo-networking packet is encapsulated in a Logical Link Control (LLC) packet. In Figure 2, the data may include a message set. The message set is, for example, a basic safety message.

[0030] BTP is a protocol for transmitting V2X messages generated in the facility layer 120 to lower layers. There are two types of BTP headers: A type and B type. A type BTP header may include the destination port and source port required for sending and receiving packets in bidirectional packet transmission. A type B BTP header may include the destination port and destination port information required for transmission in non-bidirectional packet transmission.

[0031] The following describes the fields contained in the BTP header. The destination port identifies the facility entity corresponding to the destination of the data contained in the BTP packet (BTP-PDU). The BTP-PDU is a unit of transmission data in BTP.

[0032] The source port is a field generated for the BTP-A type. The source port indicates the port of the protocol entity in the facility layer 120 at the source of the corresponding packet. This field can have a size of 16 bits.

[0033] Destination port information is a field generated for BTP-B type. It provides additional information if the destination port is a well-known port. This field can have a size of 16 bits.

[0034] The geo-networking packet includes a basic header and a common header according to the network layer protocol, and optionally includes an extension header according to the geo-networking mode. The geo-networking header will be described later.

[0035] An LLC packet is a geonetworking packet with an LLC header added. The LLC header provides the ability to distinguish between IP data and geonetworking data before transmission. IP data and geonetworking data can be distinguished by the SNAP (Subnetwork Access Protocol) Ethertype.

[0036] When IP data is transmitted, the Ethertype may be set to x86DD and included in the LLC header. When geo-networking data is transmitted, the Ethertype may be set to 0x86DC and included in the LLC header. The receiver can check the Ethertype field in the LLC packet header and forward and process the packet to the IP data path or the geo-networking path depending on the value of the Ethertype field in the LLC packet header.

[0037] The LLC header contains a Destination Service Access Point (DSAP) and a Source Service Access Point (SSAP). Following the SSAP in the LLC header are the control field (Control in Figure 2), protocol ID, and Ethertype.

[0038] FIG. 3 shows the logical interfaces for the CP service 124 and other layers in the architecture of a V2X communication device.

[0039] V2X communication devices may provide various services for road safety and efficiency. One of the services may be a cooperative awareness (CA) service. Cooperative awareness in road traffic means that road users and roadside infrastructure can know each other's location, movement, and attributes. Road users refer to all users on and around the road that are responsible for traffic safety and control, such as cars, trucks, motorcycles, bicycles, and pedestrians, while roadside infrastructure refers to facilities such as road signs, traffic lights, barriers, and entrances.

[0040] Mutual awareness is fundamental for applications such as road safety and traffic efficiency. Mutual awareness can be achieved through regular information exchange between road users, such as vehicle-to-vehicle (V2V), vehicle-to-infrastructure (V2I), infrastructure-to-vehicle (I2V) and object-to-object (X2X), based on wireless networks known as V2X networks.

[0041] Cooperative driving safety and traffic efficiency applications require V2X communication devices to have improved situational awareness, including the presence and behavior of road users around them. For example, a V2X communication device can achieve situational awareness through its own sensors or through communication with other V2X communication devices. In this case, the CA service can specify how a V2X communication device can communicate its position, behavior, and attributes by transmitting CAM.

[0042] In this way, the CA service can support road safety by having a V2X communication device periodically provide its own location and status to surrounding V2X communication devices. However, the CA service has the limitation that it can only share information about the corresponding V2X communication device itself. To overcome this limitation, the development of services such as the CP service 124 is necessary.

[0043] The CP service 124 can specify how a V2X communication device notifies other V2X communication devices about the location, behavior, and attributes of detected surrounding road users and other objects. For example, the CP service 124 can share the information contained in a CPM with other V2X communication devices by transmitting a CPM. Note that the CP service 124 may be a function that can be added to all types of target information communication devices participating in road traffic.

[0044] CPMs are messages exchanged between V2X communication devices over a V2X network. CPMs can be used to generate collective awareness of road users and other objects detected and / or recognized by the V2X communication devices. The detected road users or objects may be, but are not limited to, road users or objects that do not have V2X communication devices.

[0045] As mentioned above, V2X communication devices that share information via CAM only share information about their own perception state with other V2X communication devices to perform cooperative perception. In this case, road users without V2X communication devices are not part of the system, and therefore have a limited view of the situation related to safety and traffic management.

[0046] One way to improve this is for a system equipped with a V2X communication device that can recognize road users and objects that are not equipped with a V2X communication device to notify other V2X communication devices of the presence and status of road users and objects that are not equipped with a V2X communication device. In this way, the CP service 124 cooperatively recognizes the presence of road users and objects that are not equipped with a V2X communication device, making it possible to easily improve the safety and traffic management performance of systems equipped with V2X communication devices.

[0047] 3, the CP service 124 may be an entity in the facilities layer 120 that operates the CPM protocol. For example, the CP service 124 may be part of the application support domain of the facilities layer 120.

[0048] The CP service 124 may provide, for example, two services: transmission and reception of CPM. The CP service 124 may fundamentally differ from the CA service in that it may not receive input data about the host V2X communications device from, for example, a Vehicle Data Provider (VDP) 125 or a position and time (POTI) unit 126.

[0049] The transmission of the CPM includes generating and transmitting the CPM. In the process of generating the CPM, the originating V2X communication device generates the CPM, and then the CPM is sent to the network and transport layer 140 for transmission. The originating V2X communication device may be referred to as an originating V2X communication device, a host V2X communication device, etc.

[0050] The CP service 124 may interface with other entities in the facility layer 120 and V2X applications in the facility layer 120 to collect relevant information for CPM generation and distribute received CPM content for further processing. In a V2X communication device, the entity for data collection may be a function providing object detection in a host object detector.

[0051] Furthermore, to distribute (or transmit) the CPM, the CP service 124 may use services provided by protocol entities in the Network & Transport layer 140. For example, the CP service 124 may connect to the Network & Transport layer 140 through an NF-SAP to exchange CPMs with other V2X communication devices. The NF-SAP is a service access point between the Network & Transport layer 140 and the Facilities layer 120.

[0052] Furthermore, the CP service 124 may connect with a secure entity through an SF-SAP, which is an SAP between the security layer 160 and the facility layer 120, to access security services for sending and receiving CPMs. The CP service 124 may also connect with a management entity through an MF-SAP, which is an SAP between the management layer 150 and the facility layer 120. The CP service 124 may also connect with the application layer 110 through an FA-SAP, which is an SAP between the facility layer 120 and the application layer 110, to provide received CPM data directly to an application.

[0053] The distribution of CPM may vary depending on the applied communication system. For example, in an ITS-G5 network as defined in ETSI EN 302 663, CPM may be transmitted from the originating V2X communication device to all V2X communication devices within direct communication range. Communication range may be particularly influenced by the originating V2X communication device by varying its transmission power depending on the relevant region.

[0054] Furthermore, the CPM may be generated periodically at a frequency controlled by the CP service 124 in the originating V2X communication device. The generation frequency may be determined taking into account the wireless channel load determined by distributed congestion control. The generation frequency may also be determined taking into account the state of the detected non-V2X object, for example, dynamic behavior of position, speed, or direction, and the transmission of CPMs for the same perceived object by other V2X communication devices.

[0055] Additionally, once the receiving V2X communications device receives the CPM, the CP service 124 makes the contents of the CPM available for use by functions within the receiving V2X communications device, such as the V2X application and / or the LDM 127. For example, the LDM 127 may be updated with the received CPM data. The V2X application may retrieve this information from the LDM 127 for further processing.

[0056] 4 is a functional block diagram of the CP service 124 in this embodiment. More specifically, FIG. 4 illustrates the functional blocks of the CP service 124 in this embodiment and the functional blocks with interfaces for other functions and layers.

[0057] As shown in FIG. 4, the CP service 124 can provide the following sub-functions for CPM transmission and reception: The CPM encoder 1241 configures or generates a CPM according to a predefined format. The latest in-vehicle data may be included in the CPM. The CPM decoder 1242 decodes the received CPM. The CPM transmission manager 1243 performs protocol operations for the source V2X communication device. Operations performed by the CPM transmission manager 1243 may include starting and ending the CPM transmission operation, determining the CPM generation frequency, and triggering CPM generation. The CPM reception manager 1244 can perform protocol operations for the recipient V2X communication device. Specifically, these operations may include triggering a CPM decoding function upon CPM reception, providing received CPM data to the LDM 127 or a V2X application in the recipient V2X communication device, and checking the information of the received CPM.

[0058] Next, CPM distribution will be described in detail. Specifically, the requirements for CPM distribution, activation and termination of the CP service, CPM trigger conditions, CPM generation cycle, constraints, etc. will be described. Point-to-multipoint communication may be used for CPM distribution. For example, if ITS-G5 is used for CPM distribution, a control channel (G5-CCH) may be used. CPM generation may be triggered and managed by the CP service 124 while the CP service 124 is operating. The CP service 124 may be activated when the V2X communication device is activated and may be terminated when the V2X communication device is terminated.

[0059] The host V2X communication device may transmit a CPM whenever it detects at least one object with sufficient reliability that it needs to exchange information with nearby V2X communication devices. Regarding the inclusion of detected objects, the CP service should consider the trade-off between the object's lifetime and channel utilization. For example, from the perspective of the application that uses the information received by the CPM, it is necessary to provide updated information as frequently as possible. However, from the perspective of the ITS-G5 stack, a low transmission period is required to minimize channel utilization. Therefore, it is desirable for the V2X communication device to take this into consideration and appropriately include detected objects and object information in the CPM. Furthermore, to reduce the message size, objects must be evaluated before transmission.

[0060] FIG. 5 is a diagram illustrating the structure of a CPM. The CPM structure illustrated in FIG. 5 may be a basic CPM structure. As described above, a CPM may be a message exchanged between V2X communication devices in a V2X network. The CPM may also be used to generate collective awareness of road users and / or other objects detected and / or recognized by the V2X communication devices. That is, the CPM may be an ITS message for generating collective awareness of objects detected by the V2X communication devices.

[0061] The CPM may include status information and attribute information of road users and objects detected by the source V2X communication device. The content may vary depending on the type of detected road user or object and the detection performance of the source V2X communication device. For example, if the object is a vehicle, the status information may include at least information about the actual time, location, and motion state. The attribute information may include attributes such as dimensions, vehicle type, and role in road traffic.

[0062] The CPM may complement and function similarly to the CAM, i.e., to enhance cooperative awareness. The CPM may include externally observable information about detected road users or objects. The CP service 124 may include a method to reduce duplication or overlap of CPMs transmitted by different V2X communication devices by verifying CPMs transmitted by other stations.

[0063] Upon receiving the CPM, the receiving V2X communication device may recognize the presence, type, and status of the road user or object detected by the originating V2X communication device. The received information may be used by the receiving V2X communication device to support V2X applications to enhance safety and improve traffic efficiency and travel time. For example, by comparing the received information with the status of the detected road user or object, the receiving V2X communication device can estimate the risk of a collision with the road user or object. Furthermore, the receiving V2X communication device may notify the user via the receiving V2X communication device's human-machine interface (HMI) or automatically take corrective action.

[0064] The basic format of a CPM will be described with reference to Figure 5. This CPM format may be presented as an ASN (Abstract Syntax Notation).1 Data elements (DE) and data frames (DF) not defined in this disclosure may be derived from the Common Data Dictionary specified in ETSI TS 102 894-2. As shown in Figure 5, a CPM may include an ITS Protocol Data Unit (PDU) header and multiple containers.

[0065] The ITS PDU header contains information about the protocol version, message type, and the ITS ID of the originating V2X communication device. The ITS PDU header is a common header used in ITS messages and is located at the beginning of the ITS message. The ITS PDU header is also sometimes called a common header.

[0066] The multiple containers may include a Management Container, a Station Data Container, a Sensor Information Container, a Perceived Object Container, and a Free Space Addendum Container. The Station Data Container may include an Originating Vehicle Container or an Originating RSU Container. The Sensor Information Container may also be called a Field-of-View Container. The Originating Vehicle Container may also be written as OVC. The Field of View Container may also be written as FOC. The Perceived Object Container may also be written as POC. The CPM includes a Management Container as a required container, and the Station Data Container, Sensor Information Container, POC, and Free Space Addendum Container may be optional containers. The Sensor Information Container, Perceived Object Container, and Free Space Addendum Container may each be multiple containers. Each container is described below.

[0067] The management container provides basic information about the originating ITS-S, regardless of whether it is a vehicle or roadside unit type station. The management container may also include the station type, reference position, segmentation information, and number of recognized objects. The station type indicates the type of ITS-S. The reference position is the location of the originating ITS-S. The segmentation information describes the division information when the CPM is divided into multiple messages due to message size constraints.

[0068] Table 1 shown in Figure 6 is an example of an OVC in a station data container of a CPM. Table 1 shows data elements (DE) and / or data frames (DF) included in an example OVC. Note that the station data container becomes an OVC when the originating ITS-S is a vehicle. When the originating ITS-S is an RSU, it becomes an originating RSU container. The originating RSU container includes an ID related to the road or intersection where the RSU is located.

[0069] A DE is a data type that contains a single datum. A DF is a data type that contains one or more elements in a predefined order. For example, a DF is a data type that contains one or more DEs and / or one or more DFs in a predefined order.

[0070] DE / DF may be used to construct facility layer messages or application layer messages. Examples of facility layer messages are CAM, CPM, and DENM.

[0071] As shown in Table 1, the OVC contains basic information related to the V2X communication device that transmits the CPM. The OVC can be interpreted as a scaled-down version of the CAM. However, the OVC may contain only the DE required for the coordinate transformation process. In other words, the OVC is similar to the CAM, but provides basic information about the transmitting V2X communication device. The information contained in the OVC is focused on supporting the coordinate transformation process.

[0072] The OVC may provide the following: The OVC may provide the latest geographical location of the originating V2X communications device obtained by the CP service 124 at the time of CPM generation; The OVC may provide absolute lateral and longitudinal velocity components of the originating V2X communications device; The OVC may provide geometric dimensions of the originating V2X communications device.

[0073] The generated differential time shown in Table 1 indicates the time corresponding to the time of the reference position in the CPM as DE. The generated differential time can be considered as the generated time of the CPM. In this disclosure, the generated differential time may also be referred to as the generated time.

[0074] The reference position indicates the geographical position of the V2X communication device as DF. The reference position indicates the position of a geographical point. The reference position includes information on latitude, longitude, position confidence, and / or altitude. The latitude represents the latitude of the geographical point, and the longitude represents the longitude of the geographical point. The position confidence represents the accuracy of the geographical position, and the altitude represents the altitude and altitude accuracy of the geographical point.

[0075] The heading indicates the direction in the coordinate system as DF. The heading includes information on the heading value and / or the heading confidence. The heading value indicates the heading direction relative to north, and the heading confidence indicates a preset level of confidence in the reported heading value.

[0076] The longitudinal speed can be described as DF, which describes the longitudinal speed and the accuracy of the speed information for a moving body (e.g., a vehicle). The longitudinal speed includes information on the speed value and / or the speed accuracy. The speed value represents the longitudinal speed value, and the speed accuracy represents the accuracy of the speed value.

[0077] The lateral velocity, DF, can describe the lateral velocity and accuracy of the velocity information for a moving body (e.g., a vehicle). The lateral velocity includes information about the velocity value and / or velocity accuracy. The velocity value represents the lateral velocity value, and the velocity accuracy represents the accuracy of the velocity value.

[0078] The vehicle length can be described as a vehicle length and an accuracy index as a DF. The vehicle length includes information about the vehicle length value and / or the vehicle length accuracy index. The vehicle length represents the length of the vehicle, and the vehicle length accuracy index represents the reliability of the vehicle length.

[0079] Vehicle width is expressed as DE, which indicates the width of the vehicle. For example, vehicle width can be expressed as the width of the vehicle including the side mirrors. If the vehicle width is 6.1 m or more, it is set to 61, and if this information is unavailable, it is set to 62.

[0080] Each DE / DF in Table 1, except for the generation time difference, can refer to ETSI 102 894-2 shown in the right column of Table 1. ETSI 102 894-2 defines the CDD (common data dictionary). For the generation time difference, refer to ETSI EN 302 637-2.

[0081] In addition to the above information, the OVC may also include information regarding vehicle direction angle, vehicle traveling direction, longitudinal acceleration, lateral acceleration, vertical acceleration, yaw rate, pitch angle, roll angle, vehicle height, and trailer data.

[0082] Table 2 is shown in Figure 7. Table 2 is an example of SIC (or FOC) in CPM. SIC provides a description of at least one sensor installed in the source V2X communication device. If the V2X communication device is equipped with multiple sensors, multiple descriptions may be added. For example, SIC provides information about the sensor capabilities of the source V2X communication device. To do this, general sensor characteristics providing the sensor installation location, sensor type, sensor range, and sensor opening angle (i.e., sensor frustum) of the source V2X communication device may be included as part of the message. This information may be used by the receiving V2X communication device to select an appropriate prediction model according to the sensor performance.

[0083] Various types of information in the SIC will be described with reference to Table 2. The sensor ID indicates a sensor-specific ID for identifying the sensor that detected the object. In the embodiment, the sensor ID is a random number that is generated when the V2X communication device is started up, and is not changed until the V2X communication device is shut down.

[0084] The sensor type indicates the type of sensor. The sensor types are listed below. For example, sensor types are undefined (0), radar (1), lidar (2), mono video (3), stereo vision (4), night vision (5), ultrasonic (6), pmd (7), fusion (8), induction loop (9), spherical camera (10), and a combination of these (11). pmd is a photo mixing device. A spherical camera is also called a 360-degree camera.

[0085] Regarding the sensor position, the X position indicates the installation position of the sensor in the negative X direction, and the Y position indicates the installation position of the sensor in the Y direction. These installation positions are measured from the reference position, and the reference position can refer to ETSI EN 302 637-2. The radius indicates the average recognition range of the sensor defined by the manufacturer.

[0086] In the opening angle, the start angle indicates the start angle of the sensor frustum, and the end angle indicates the end angle of the sensor frustum. The quality class indicates the classification of the sensor that defines the quality of the measurement object.

[0087] In addition to the above information, the SIC may also include information on the reliability of the detection area and free space.

[0088] Figure 8 shows Table 3, which is an example of POC in CPM. POC is used to describe the object recognized by the sensor from the perspective of the transmitting V2X communication device. Upon receiving the POC, the receiving V2X communication device can perform coordinate transformation processing to convert the object's position into the reference coordinate system of the receiving vehicle with the help of OVC.

[0089] To reduce the message size, multiple options DE may be provided if the originating V2X communication device can provide them.

[0090] The POC may be configured with a selection of DEs to provide an abstract description of a recognized (or detected) object. For example, relative distance, velocity, and timing information about a recognized object relative to the originating V2X communications device may be included in the POC as a required DE. Additional DEs may also be provided if the originating V2X communications device's sensors can provide the requested data.

[0091] Each piece of information (DE or DF) is explained with reference to Table 3. The measurement time indicates the time from the reference time of the message in microseconds. This defines the relative age of the measured object.

[0092] The object ID is a unique random ID assigned to the object that is maintained (i.e., does not change) while the object is being tracked, i.e., considered in the data fusion process of the originating V2X communication device.

[0093] The sensor ID is an ID that corresponds to the DE of the sensor ID in Table 2. This DE may be used to associate object information with the sensor that performed the measurement.

[0094] The vertical distance includes a distance value and a distance confidence. The distance value indicates the relative X distance to the object in the source reference frame. The distance confidence is a value indicating the confidence of that X distance.

[0095] The lateral distance also includes a distance value and a distance confidence. The distance value indicates the relative Y distance to the object in the source reference coordinate system, and the distance confidence indicates the confidence of the Y distance.

[0096] The longitudinal velocity indicates the longitudinal velocity of the detected object according to the confidence level. The lateral velocity indicates the lateral velocity of the detected object according to the confidence level. The longitudinal velocity and lateral velocity can refer to the CDD of TS 102 894-2.

[0097] Object Orientation, if provided by the data fusion process, indicates the absolute orientation of the object in a reference coordinate system. Object Length, indicates the measured object length. Length Confidence, indicates the confidence in the measured object length. Object Width, indicates the object width measurement. Width Confidence, indicates the confidence in the object width measurement. Object Type, if provided by the data fusion process, indicates the object classification. Object classifications may include vehicle, person, animal, etc. In addition to the above information, the POC may also include information regarding the object's reliability, vertical distance, vertical speed, longitudinal acceleration, lateral acceleration, vertical acceleration, object height, object dynamic state, and matched position (including lane ID and longitudinal lane position).

[0098] The free space add container is a container that indicates information about the free space recognized by the source V2X communication device (i.e., free space information). Free space is an area that is not considered to be occupied by road users or obstacles, and can also be referred to as an empty space. Free space can also be referred to as a space in which a moving object traveling with the source V2X communication device can move.

[0099] The free space addition container is not a required container but can be added arbitrarily. A free space addition container can be added when there is a difference between the free space recognized by another V2X communication device, which can be calculated from the CPM received from the other V2X communication device, and the free space recognized by the source V2X communication device. In addition, a free space addition container may be added to the CPM periodically.

[0100] The free space add container includes information that specifies the area of free space. Free space can be specified by various shapes. The shape of free space can be expressed, for example, as a polygon, circle, ellipse, or rectangle. When expressing free space as a polygon, the positions of the multiple points that make up the polygon and the order in which these multiple points are connected are specified. When expressing free space as a circle, the position of the center of the circle and the radius of the circle are specified. When expressing free space as an ellipse, the position of the center of the ellipse and the major and minor axes of the ellipse are specified.

[0101] The free space adder container may include the reliability of the free space. The reliability of the free space is expressed as a numerical value. The reliability of the free space may also indicate that the reliability is unknown. The free space adder container may also include information about a shadow area. A shadow area indicates an area behind an object as seen from a vehicle or a sensor mounted on the vehicle.

[0102] Figure 9 is a diagram illustrating the reliability of free space. Assume that a sensor for detecting objects is mounted on the front end of vehicle 5. A square represents an object. A triangular area A1 indicated by a solid line and an area A2 surrounded by a two-dot chain line on the farther side of the triangle from vehicle 5 are both within the sensor's detection range A. However, area A2 surrounded by a two-dot chain line is located farther from the sensor than area A1 indicated by a solid line, and therefore is an area with reduced reliability. Within area A1 indicated by a solid line, area A3 indicated by a dashed dot line, i.e., the area extending from the side of the object toward the distance from the vehicle, is an area with relatively lower reliability than other areas within area A1 indicated by a solid line due to occlusion by the object. Furthermore, area A4, the shadow area of the object extending toward the distance from the vehicle, is difficult for the sensor to recognize, and therefore cannot be evaluated for reliability.

[0103] 10A and 10B are diagrams illustrating a method for extracting sensor data by a V2X communication device that provides CP services. More specifically, FIG. 10A illustrates a method for extracting sensor data by a V2X communication device at a low level. FIG. 10B illustrates a method for extracting sensor data by a V2X communication device at a high level.

[0104] The source of the sensor data transmitted as part of the CPM needs to be selected according to the requirements of the future data fusion process in the receiving V2X communication device. In general, the transmitted data should be as close as possible to the original sensor data. However, simply transmitting the original sensor data, e.g., raw data, is not practical, as it imposes very high requirements on data rate and transmission period.

[0105] Figures 10(a) and 10(b) show possible embodiments for selecting data to be transmitted as part of a CPM. In the embodiment of Figure 10(a), sensor data is acquired from different sensors and processed as part of a low-level data management entity. This entity can select object data to be inserted as part of the next CPM and can also calculate the validity of detected objects. In Figure 10(a), transmitting data from each sensor increases the amount of data transmitted over the V2X network. However, this allows the receiving V2X communication device to efficiently utilize the sensor information.

[0106] In the embodiment of FIG. 10(b), sensor data or object data provided by a data fusion unit specific to the V2X communication equipment manufacturer is transmitted as part of the CPM.

[0107] In Figure 10(b), the integrated sensor data collected via the data fusion unit is transmitted, which has the advantage of reducing the amount of data transmitted via the V2X network. However, it has the disadvantage of being dependent on the collection method used by the V2X communication device to collect sensor information. In addition, different manufacturers may implement different data fusion processes.

[0108] Each time an object is detected by the sensor of the V2X communication device, its likelihood must be calculated. If the object likelihood exceeds a predetermined threshold PLAUS_OBJ, transmission must be considered.

[0109] For example, transmission may be considered if the absolute value of the difference between the current yaw angle of the detected object and the yaw angle included in a CPM previously transmitted by the originating V2X communications device exceeds 4 degrees. Transmission may also be considered if the difference between the relative distance between the originating V2X communications device and the detected object's current position and the relative distance between the originating V2X communications device and the detected object included in a CPM previously transmitted by the originating V2X communications device exceeds 4 m, or if the absolute value of the difference between the detected object's current speed and the detected object's speed included in a CPM previously transmitted by the originating V2X communications device exceeds 0.5 m / s.

[0110] CAM is a technology that supports more stable driving by allowing vehicles equipped with V2X modules to periodically transmit their location and status to surrounding vehicles equipped with V2X modules. Note that V2X modules are V2X communication devices or devices that include V2X communication devices.

[0111] CAM was limited in that it could only share information about its own vehicle. CP Service 124 is a technology that complements CAM. As the number of vehicles equipped with ADAS technology continues to increase, many vehicles are equipped with sensors such as cameras, radar, and lidar, which recognize many surrounding vehicles and provide driving assistance functions. CPS (i.e., CP Service) technology is an ADAS technology that uses V2X communication to notify surrounding areas of sensor data that recognizes the surrounding environment.

[0112] FIG. 11 is a diagram illustrating the CP service 124. Each of the vehicles TxV1 and RxV2 is equipped with at least one sensor and has sensing ranges SrV1 and SrV2 indicated by dotted lines. TxV1 has a CPS function. Using multiple ADAS sensors mounted on the vehicle, TxV1 can recognize vehicles RV1 to RV11 that are surrounding objects belonging to the sensing range SrV1. Object information obtained through recognition may be distributed via V2X communication to surrounding vehicles equipped with V2X communication devices.

[0113] As a result, among the surrounding vehicles that receive the CPM from TxV1, RxV1, which does not have a sensor, can obtain information about the following vehicle. Also, when RxV2, which has a sensor, receives the CPM from TxV1, it can also obtain information about objects outside the sensing range SrV2 of RxV2 or objects located in its blind spot (for example, RV1-3, RV5, 6, and RV8-10).

[0114] 3 above, the facility layer 120 may provide a CP service 124. The CP service 124 may run in the facility layer 120 or may use a service present in the facility layer 120.

[0115] The LDM 127 is a service that provides map information and may provide map information for the CP service 124. The provided map information may include dynamic information in addition to static information. The POTI unit 126 executes a service that provides the position and time of the vehicle. The POTI unit 126 can provide the position of the vehicle and the accurate time using the corresponding information. The VDP 125 is a service that provides information about the vehicle and may use this to import information such as the size of the vehicle into the CPM and transmit the CPM.

[0116] ADAS vehicles are equipped with various sensors for driving assistance, such as cameras, infrared sensors, radar, and lidar. Each sensor recognizes objects individually. The recognized object information may be collected and fused by a data fusion unit and provided to the ADAS application.

[0117] Referring again to FIG. 10, a method for collecting and fusing sensor information in ADAS technology will be described with respect to the CP service 124. Existing sensors for ADAS and existing sensors for CPS can constantly track surrounding objects and collect related data. When using sensor values for the CP service, two methods can be used to collect sensor information.

[0118] As shown in Fig. 10(a), each sensor value can be individually provided to nearby vehicles through the CP basic service. Also, as shown in Fig. 10(b), integrated sensor information collected after the data fusion section may be provided to the CP basic service. The CP basic service constitutes a part of the CP service 124.

[0119] [Configuration of the in-vehicle system 10] 12 shows a configuration diagram of an in-vehicle system 10 including a V2X communication device 60. In addition to the functions and configuration of the V2X communication device described above, the V2X communication device 60 also has the configuration described below.

[0120] The in-vehicle system 10 is mounted on a vehicle 5. In addition to a V2X communication device 60, the in-vehicle system 10 includes a sensor 20, a map data storage unit 30, a position detection unit 40, and a target detection unit 50.

[0121] The sensor 20 is mounted on the vehicle 5 to detect targets. A target is an object detected by the sensor 20. The objects described so far can also be referred to as targets. Targets exist outside the vehicle 5. Targets can include moving objects and stationary objects. Moving objects include, for example, four-wheeled vehicles, two-wheeled vehicles, pedestrians, animals, etc. Stationary objects include, for example, pylons, warning triangles, parked vehicles, utility poles, fallen objects, etc. A plurality of sensors 20 can be provided. The sensor 20 can include, for example, a camera, a lidar, a radar, a sonar, etc.

[0122] The map data storage unit 30 stores road map data. The road map data is data that represents road shapes. The road shapes can be represented by nodes and links. The road map data may also be high-precision map data. The high-precision map data is map data that represents the positions and shapes of features such as lane lines, road shoulders, and road signs. The road map data stored in the map data storage unit 30 may be updated with update map data distributed from a map distribution center.

[0123] The position detection unit 40 sequentially detects the current position. For example, the position detection unit 40 includes a GNSS receiver that receives navigation signals transmitted by navigation satellites included in the GNSS (Global Navigation Satellite System), and sequentially detects the current position based on the navigation signals received by the GNSS receiver. The current position is expressed by coordinates including latitude and longitude. The coordinates may also include altitude.

[0124] The target detection unit 50 acquires signals from the sensor 20 and detects various targets present around the vehicle 5. The target detection unit 50 can be realized by a configuration including at least one processor. For example, the target detection unit 50 can be realized by a computer including a processor, a non-volatile memory, a RAM (Random Access Memory), an I / O (Input / Output), and a bus line connecting these components.

[0125] The V2X communication device 60 includes a communication circuit 61 and a control unit 63. The communication circuit 61 includes a modulation circuit, a demodulation circuit, an amplification circuit, and the like. The communication circuit 61 modulates and amplifies a message provided by the control unit 63 and transmits the message from the antenna 62. The communication circuit 61 also demodulates and amplifies a message from a radio wave received by the antenna 62 and provides the message to the control unit 63. There are no particular limitations on the frequency used for transmission and reception (i.e., communication). The frequency used for communication is, for example, the 5 GHz band. The frequency used for communication may also be the 700 MHz band. The communication circuit 61 can be a circuit that performs short-range wireless communication. However, the communication circuit 61 may also be a circuit that performs wide-area wireless communication. When short-range wireless communication is performed, the communication range is from several hundred meters to several kilometers. The communication performed by the V2X communication device 60 is V2X communication.

[0126] The control unit 63 can be realized by a configuration including at least one processor. For example, the control unit 63 can be realized by a computer including a processor, a nonvolatile memory, a RAM, an I / O, and a bus line connecting these components. A target information communication program for operating a general-purpose computer as the control unit 63 is stored in the nonvolatile memory. The processor executes the target information communication program stored in the nonvolatile memory while utilizing the temporary storage function of the RAM, causing the control unit 63 to operate as a message acquisition unit 64, a target characteristic estimation unit 65, a prediction unit 66, and a target information transmission unit 67. Execution of these operations means that a target information communication method corresponding to the target information communication program is being executed.

[0127] The control unit 63 acquires information from the target detection unit 50, the map data storage unit 30, and the position detection unit 40. More specifically, the target characteristic estimation unit 65 acquires information from the target detection unit 50, and the prediction unit 66 acquires information from the map data storage unit 30 and the position detection unit 40. The control unit 63 also communicates with various devices mounted on the vehicle 5 via an in-vehicle network 70. Through this communication, the control unit 63 may acquire information necessary for generating a CPM. The in-vehicle network 70 may be, for example, Ethernet, CAN (Controller Area Network), LIN (Local Interconnect Network), CXPI (Clock Extension Peripheral Interface), FlexRay, MOST (Media Oriented Systems Transport), etc. Ethernet, CAN, CXPI, FlexRay, and MOST are registered trademarks.

[0128] The message acquisition unit 64 acquires, via the antenna 62 and the communication circuit 61, a message transmitted by a V2X communication device (hereinafter referred to as another communication device) mounted on another moving body different from the vehicle 5 on which the V2X communication device 60 is mounted. The messages transmitted by the other communication device include CAM, CPM, DENM, etc. As described with reference to FIG. 9, the CPM may include a free space addition container indicating free space information. Therefore, the message acquisition unit 64 is a free space information acquisition unit.

[0129] The target characteristic estimation unit 65 estimates the characteristics of the target detected by the target detection unit 50 (hereinafter referred to as the target characteristic). The target characteristic is one or more of the various characteristics shown in Table 3. The target characteristic can also be referred to as a state space representation of the target. In addition to the target characteristic, the target characteristic estimation unit 65 may generate an environment model. The environment model is a computational representation of the environment around the ITS-S. The environment model can be generated based on various targets detected by the target detection unit 50. The target characteristic estimation unit 65 may also determine the reliability of the target (in other words, the reliability of the object). The reliability of the object can be determined, for example, based on the degree of agreement between the detection results of the multiple sensors 20. The numerical representation of the reliability of the object may be as follows: The reliability of the object is expressed as a number from 1 to 100, and if the reliability is unknown, it is set to 0. Furthermore, if the reliability cannot be calculated, the number may be set to 101. The reliability can also be referred to as a reliability degree.

[0130] The prediction unit 66 predicts whether the target, whose target characteristics have been estimated by the target characteristic estimation unit 65, will move into a space in which a mobile body equipped with the V2X communication device 60 that transmits a CPM including free space information can move. This prediction uses the target characteristics and free space information. Furthermore, it is preferable that road shape information also be used for this prediction. The road shape information is information indicating the shape of a road and is acquired from the map data storage unit 30. The road shape information may be information indicating the shape of a road using nodes and links. Furthermore, in addition to or instead of nodes and links, the road shape information may be information indicating the shape of a road by indicating areas that are roads. The road shape information may also include more detailed information, such as areas that are roadways, areas that are sidewalks, and the presence or absence of a median strip.

[0131] The processing of the prediction unit 66 will be specifically described using Figures 13 and 14. Figures 13 and 14 show a host vehicle 5a and other vehicles 5b and 5c as vehicles 5. An obstruction 8 that blocks the view is present next to an intersection where the road on which the host vehicle 5a is traveling intersects with the road on which the other vehicle 5b is traveling. Assume that the host vehicle 5a and the other vehicles 5b and 5c are equipped with an in-vehicle system 10. The processing of the prediction unit 66 will be specifically described using the in-vehicle system 10 equipped in the host vehicle 5a as an example.

[0132] The host vehicle 5a estimates the relative distance and moving direction of the targets 6a and 6b using the target characteristic estimation unit 65. Therefore, the in-vehicle system 10 installed in the host vehicle 5a recognizes that the targets 6a and 6b are located at the positions shown in Fig. 13 or 14 and are moving in the directions indicated by the arrows.

[0133] Assume that the other vehicles 5b and 5c transmit CPMs including free space information. By receiving the CPMs, the in-vehicle system 10 installed in the subject vehicle 5a can recognize the free space 7b for the other vehicle 5b and the free space 7c for the other vehicle 5c.

[0134] In the example of Fig. 13, the in-vehicle system 10 mounted on the host vehicle 5a can predict that the two targets 6a and 6b will move to the free spaces 7b and 7c based on the positions and traveling directions of the targets 6a and 6b, free space information, and road shape. The free spaces 7b and 7c are spaces into which the other vehicles 5b and 5c can move, respectively. Therefore, in the example of Fig. 13, the in-vehicle system 10 mounted on the host vehicle 5a predicts that the targets 6a and 6b will move to spaces into which the other vehicles 5b and 5c can move, respectively.

[0135] 14, there is a median strip 9 on the road on which the host vehicle 5a is traveling. The on-board system 10 mounted on the host vehicle 5a can recognize the presence of the median strip 9 from the sensor 20 or road shape information. Because there is the median strip 9, the on-board system 10 mounted on the host vehicle 5a can predict that the target 6b will not move into a space where the other vehicles 5b and 5c can move.

[0136] 14, the on-board systems 10 mounted on the other vehicles 5b and 5c also recognize the median strip 9. Therefore, the free spaces 7b and 7c are also limited in area by the median strip 9. Therefore, the movement direction of the target 6b is not a direction toward the free spaces 7b and 7c. This also leads to prediction that the target 6b will not move into a space where the other vehicles 5b and 5c can move.

[0137] On the other hand, in the example of FIG. 14, the in-vehicle system 10 installed in the host vehicle 5a can also predict that the target 6a will move into a space where the other vehicles 5b and 5c can move.

[0138] The free spaces 7b and 7c may be corrected based on the road shape to determine the spaces in which the other vehicles 5b and 5c can move. For example, based on the road shape, the predicted spaces in which the other vehicles 5b and 5c can move may be limited to intersections and junctions on the road on which the target 6 is traveling. This is because if the target 6 and the other vehicles 5b and 5c continue to travel on different roads, the other vehicles 5b and 5c have little need to recognize the presence of the target 6.

[0139] Furthermore, the shape of the road can also be used to predict the path that the target object 6 will take. This is because it is possible to predict that a target object 6 on a road will move along the road. Even if the targets 6a and 6b are moving toward the free space 7b, if, unlike in FIG. 13, the road on which the targets 6a and 6b exist does not intersect with the road on which the other vehicle 5b is traveling, it can be determined that the targets 6a and 6b will not move onto the road on which the other vehicle 5b is traveling.

[0140] In this way, the prediction unit 66 preferably also uses road shape information to predict whether the target 6 will move into a space where other vehicles 5b, 5c, or other moving objects can move. However, the prediction may be made using target characteristics and free space information without using road shape information. For example, if the moving direction of the target 6 indicated by the target characteristics is heading toward the free space 7 indicated by the free space information, it may be predicted that the target 6 will move into a space where the moving object that transmitted the free space information can move.

[0141] The target information transmitter 67 transmits the CPM to the surrounding area. The CPM can be transmitted by point-to-multipoint communication. However, the CPM may also be transmitted by a communication method other than point-to-multipoint communication, such as point-to-point communication. The CPM may include target information. The target information is information that identifies the target 6. The target information is information about the POC or part of the POC.

[0142] The target information transmitting unit 67 determines a priority for each target, and based on the priority, determines which target information of which target 6 should be included in the CPM. When the prediction unit 66 predicts that the target 6 will move into a space where a moving object such as another vehicle 5b or 5c can move, the target information transmitting unit 67 can increase the priority of transmitting the target information for that target 6 compared to when the prediction unit 66 does not predict that the target 6 will move into a space where a moving object can move.

[0143] For example, in the example of FIG. 14 , the prediction unit 66 sets a higher priority for transmitting target information for target 6a than for transmitting target information for target 6b. If the priority is set higher, including all target information in a CPM would result in a CPM size that is too large. In this case, only target information with a relatively high priority can be included in the CPM to be transmitted this time. Target information with a relatively low priority will be included in the next or subsequent CPM. Not transmitting target information with a relatively low priority is also an example of processing based on priority.

[0144] 13, the priorities that can be determined from the positions and moving directions of the targets 6a and 6b, free space information, and road shape information are the same for both the targets 6a and 6b. When the prediction unit 66 predicts that there are multiple targets 6 moving in the space where the moving object can move, the target information transmission unit 67 can determine the priorities using further information.

[0145] An example of other information is Time To Collision (TTC). TTC is the time required to reach the point where a collision is predicted, and can be calculated by dividing the distance to that point by the speed. In FIG. 13, the in-vehicle system 10 mounted on the host vehicle 5a receives the CPM transmitted by the other vehicles 5b and 5c, which includes the positions and speeds of the other vehicles 5b and 5c in the OVC. Furthermore, the in-vehicle system 10 mounted on the host vehicle 5a can estimate the positions and speeds of the targets 6a and 6b using the target characteristic estimation unit 65. Therefore, the in-vehicle system 10 mounted on the host vehicle 5a can calculate the TTC between the targets 6a and 6b and the other vehicles 5b and 5c.

[0146] The TTC between the target object 6b and the other vehicle 5b is 2 seconds, and the TTC between the target object 6a and the other vehicle 5c is 3 seconds. Note that the target object 6a and the other vehicle 5b are traveling in opposite directions but do not collide, so the TTC is not calculated.

[0147] When the priorities that can be determined from the positions and movement directions of the targets 6a and 6b, free space information, and road shape information are the same, the target information transmitting unit 67 can determine the priority for transmitting the target information based on the TTC (for example, in ascending order of TTC).

[0148] The TTC may be calculated precisely and the priority may be determined based on the TTC. However, if the TTCs are the same, the priority may be determined based on whether the target 6 and the other vehicles 5b and 5c are traveling on the same road, rather than comparing slight differences in TTC.

[0149] For example, in the example of FIG. 13, assume that the moving speed of target 6b is slower than that of target 6a, and the TTC between target 6b and other vehicle 5b and the TTC between target 6a and other vehicle 5c are at the same level. The range of TTCs that are considered to be at the same level can be set as appropriate. For example, if the difference between two TTCs is within a certain time, the TTCs can be considered to be at the same level. Also, if the difference between the TTCs is equal to or less than a small, preset ratio, such as 10%, of one of the calculated TTCs, the TTCs may be considered to be at the same level. Also, if the variance of multiple TTCs is within a certain value, the TTCs may be considered to be at the same level.

[0150] If the TTC is the same level, the priority is given to the case where the target object 6 and the moving object are on different roads rather than the case where they are on the same road. Even if an intersection is between them, the area in which they can travel along the road is the same road. On the other hand, if a right or left turn is required, the roads before and after the right or left turn are different roads. In the example of FIG. 13, the target object 6a and the other vehicle 5c are on the same road. On the other hand, the target object 6b and the other vehicle 5b are on different roads. Therefore, the target object information transmitter 67 gives a higher priority to transmitting target object information about the target object 6b than to transmitting target object information about the target object 6a.

[0151] When there are multiple combinations of a target object 6 and a moving object that exist on the same road, the target object information transmitter 67 cannot determine the priority based on whether the target object 6 and the moving object exist on the same road or on different roads. In this case, the target object information transmitter 67 further compares the road width direction length of the space in which the moving object can move based on the free space information. Then, the target object information transmitter 67 assigns a higher priority to transmitting target object information for a target object 6 that moves into a space that is shorter in the road width direction.

[0152] In FIG. 15, the target 6a is located in a different position from that in FIG. 13. More specifically, in FIG. 15, the target 6a is located on the same road as the other vehicle 5b. For the other vehicle 5b, the area where the target 6a is located is not free space 7b. Therefore, the free space 7b recognized by the other vehicle 5b has a shorter length in the road width direction than the free space 7b shown in FIG. 13 at the position of the target 6a and in an area farther from the other vehicle 5b. In other words, the free space is reduced by the area where the target 6a is located and the area behind the target 6a as seen from the other vehicle 5b (the shaded area in FIG. 9).

[0153] In the example of Fig. 15, the TTC between the target object 6a and the other vehicle 5c and the TTC between the target object 6b and the other vehicle 5b are assumed to be at the same level. Therefore, the lengths of the space in the road width direction within which the other vehicles 5b and 5c can move are compared. The space for which the lengths of the road width direction are compared is preferably a portion of the space in which the other vehicles 5b and 5c can move that overlaps with the road on which the target object 6 is moving. This is because there is a possibility of contact between the target object 6 and the other vehicle 5b in this portion.

[0154] The intersection is the area where other vehicle 5b may come into contact with target object 6b. The intersection is also the area where other vehicle 5c may come into contact with target object 6a. Therefore, the lengths of free spaces 7b and 7c in the road width direction within the intersection are compared. The length of free space 7b in the road width direction of free spaces 7b and 7c in the intersection is shorter than that of free space 7b. Therefore, the target information transmitter 67 gives a higher priority to transmitting the target characteristics of target object 6b than to transmitting the target characteristics of target object 6a.

[0155] Here, the correspondence between the functional block diagram of the CP service 124 shown in Fig. 4 and the functions of the control unit 63 shown in Fig. 12 will be described. The message acquisition unit 64 is part of the functions of the CPM decoding unit 1242 and the CPM reception management unit 1244. The target characteristic estimation unit 65, the prediction unit 66, and the target information transmission unit 67 are functions for generating and transmitting CPMs, and are part of the functions of the CPM transmission management unit 1243. Furthermore, within the target information transmission unit 67, the function of determining the data to be included in the CPM and then finally generating and transmitting the data is part of the functions of the CPM encoding unit 1241.

[0156] [CPM sending process] Fig. 16 shows the process of transmitting a CPM. The process shown in Fig. 16 is executed by the target information transmission unit 67 at a predetermined execution cycle. In S1, it is determined whether T_Now-T_LastCpm is equal to or greater than T_GenCpm. T_Now is the current time. T_LastCpm is the time when the CPM was last transmitted. T_GenCpm is the cycle for generating a CPM. Therefore, in S1, it is determined whether the cycle for transmitting a CPM has elapsed since the last CPM was transmitted.

[0157] In S2, T_GenEvent is set to T_Now. T_GenEvent means the time when the event that generates the CPM occurs. By setting T_GenEvent to T_Now, the time when the CPM is generated becomes the current time.

[0158] In S3, candidates for recognition objects are selected. A recognition object means a target whose target characteristics are included in a recognition object container. Details of the process in S3 are shown in Figure 17.

[0159] In FIG. 17, in S301, a list of objects is obtained from the environment model and stored in an object list. The environment model is generated by the target characteristic estimation unit 65. The environment model is an example of a representation form of the results of the target characteristic estimation unit 65 estimating the target characteristics of various targets. That is, in S301, a list of target characteristics estimated by the target characteristic estimation unit 65 is obtained. The object list is a list for selecting candidates for recognized objects in the processing of FIG. 17. A recognized object can also be simply referred to as an object or a target.

[0160] In S302, it is determined whether an object has been detected. If the determination result in S302 is NO, the process of S3 is terminated and the process proceeds to S4. If the determination result in S302 is YES, the process proceeds to S303.

[0161] In S303, the next object is acquired from the object list. In S304, it is determined whether the reliability of the object is equal to or greater than a preset threshold. Note that S304 may be omitted and the process proceeds to S305. For example, if the reliability of the object has not been determined, S304 may be omitted. The reliability of the object is determined by the target characteristic estimation unit 65. If the determination result of S304 is NO, the process proceeds to S311 in FIG. 18. If the determination result of S304 is YES, the process proceeds to S305.

[0162] In S305, it is determined whether the object has been stored in a predetermined area of the internal memory. The internal memory is a memory provided in the control unit 63, and the predetermined area is an area for saving data for generating a CPM. If the determination result in S305 is NO, that is, if the object acquired in S303 has already been stored in the internal memory, the process proceeds to S310 in Fig. 18. If the determination result in S305 is YES, the process proceeds to S306.

[0163] In S306, it is determined whether the object acquired in S303 belongs to a human or animal class, that is, it is determined whether the type of the object acquired in S303 is a human or an animal.

[0164] If the determination result in S306 is NO, proceed to S307. In S307, it is determined whether at least one of the object's distance, speed, direction, and elapsed time has changed by more than a predetermined threshold value since the previous CPM transmission. If the determination result in S307 is YES, proceed to S310 in FIG. 18. On the other hand, if the determination result in S307 is NO, proceed to S311 in FIG. 18.

[0165] If the determination result in S306 is YES, the process proceeds to S308. In S308, it is determined whether 500 ms or more have passed since the object acquired in S303 was included in the CPM. If the determination result in S308 is NO, the process also proceeds to S311 in FIG. 18. If the determination result in S308 is YES, the process proceeds to S309. In S309, all people and animals are included in the CPM to be generated. Thereafter, the process proceeds to S310 in FIG. 18.

[0166] Referring now to Figure 18, in S310, the object ID and T_GenEvent are stored in internal memory, and the stored information is marked for transmission.

[0167] In S311, it is determined whether the object is the last object in the object list. If the determination result in S311 is NO, the process returns to S303. If the determination result in S311 is YES, the process proceeds to S312. In S312, a list of candidates for the recognized object container is created based on the mark. After S312 is executed, the process proceeds to S4 in FIG. 16.

[0168] In S4 of FIG. 16, a sensor information container is generated. Details of the processing of S4 are shown in FIG. 19. In FIG. 19, in S41, it is determined whether the value obtained by subtracting T_LastSensorInfoContainer from T_Now is equal to or greater than T_AddSensorInformation. T_LastSensorInfoContainer is the time when the last sensor information container was generated. T_AddSensorInformation indicates the period for adding a sensor information container. If the determination result in S41 is NO, FIG. 19 ends and the process proceeds to S5 of FIG. 16. If the determination result in S41 is YES, the process proceeds to S42.

[0169] In S42, the sensor parameters are obtained by querying a database that stores the sensor parameters.

[0170] In S43, a sensor information container is generated based on the sensor parameters acquired in S42. An example of the generated sensor information container is Table 2 described above.

[0171] In S44, T_LastSensorInfoContainer is set to T_GenEvent. That is, the time when the sensor information container was generated is set to the time when S2 is executed when the next CPM is created. When the processing in FIG. 19 is completed, the process proceeds to S5 in FIG. 16.

[0172] In S5 of Fig. 16, it is determined whether POC (i.e., recognition object container) or SIC (i.e., sensor information container) data has been generated. If neither POC nor SIC has been generated, the determination result in S5 is NO. If the determination result in S5 is NO, the processing in Fig. 16 ends without transmitting the CPM. If the determination result in S5 is YES, proceed to S6.

[0173] In S6, an OVC (i.e., a sending vehicle container) and a management container are generated. The processing of S6 is shown in Figure 20. In Figure 20, in S61, a station type is selected. If the station type is a car, the process proceeds to S62. In S62, a sending vehicle container is generated. The sending vehicle container is, for example, one shown in Table 1. After executing S62, the process proceeds to S65.

[0174] If the determination in S61 indicates that the station type is an RSU, proceed to S63. In S63, determine whether to transmit a MAP message. A MAP message is a message that provides the shape of an intersection or road segment around the RSU. If the determination result in S63 is YES, proceed to S64. In S64, generate a source RSU container that includes the MAP message. Then, proceed to S65. If the determination result in S63 is NO, proceed to S65 without executing S64.

[0175] In S65, a management container for an undivided CPM is generated, which may include a station type, a reference position, segmentation information, and the number of recognized objects.

[0176] In S66, the encoding size of the CPM including all the generated containers is calculated. Note that the CPM can include a free space additional container. If a free space additional container is generated, the encoding size of the CPM is calculated including the size of the free space additional container.

[0177] In S67, it is determined whether the size of the encoded CPM exceeds MTU_CPM. MTU_CPM is the maximum transmission unit of one CPM and is set in advance. MTU_CPM is determined depending on the maximum transmission unit of the access stratum 130.

[0178] If the determination result in S67 is NO, proceed to S68. In S68, a CPM including all of the generated containers is generated. Thereafter, proceed to S7 in FIG. 16. On the other hand, if the determination result in S67 is YES, proceed to S69. In S69, the segments of the message are determined. Detailed processing of S69 is shown in FIG. 21.

[0179] In Figure 21, in S691, objects are sorted in order of priority. Detailed processing of S691 is shown in Figure 23. In the explanation of Figure 23, an object is represented as a target 6. In Figure 23, in S6911, it is determined whether there are multiple targets 6 in the list of recognized object containers created in S312. If the determination result of S6911 is NO, sorting is not necessary, so the processing of Figure 23 is terminated. If the determination result of S6911 is YES, the processing proceeds to S6912. It is assumed that, before proceeding to S6912, the priorities of the multiple targets 6 included in the list of recognized object containers are all the same.

[0180] In S6912, priorities are assigned based on whether the target 6 moves into a space that the moving body that transmitted the CPM can move in. For example, in the example shown in Fig. 14, the priority of the target 6a is set higher than the priority of the target 6b.

[0181] In S6913, it is determined whether or not there is a target 6 with the same priority. If the determination result in S6913 is NO, the process proceeds to S6919. If the determination result in S6913 is YES, the process proceeds to S6914.

[0182] In S6914, priorities are assigned based on the level of the TTC between the target 6 and the moving object. In the example of Fig. 13, the TTC between the target 6b and the other vehicle 5b is 2 seconds, and the TTC between the target 6a and the other vehicle 5c is 3 seconds. In this case, the priority of the target 6b is set higher than the priority of the target 6a.

[0183] In S6915, it is determined again whether or not there is a target 6 with the same priority. If the determination result in S6915 is NO, the process proceeds to S6919. If the determination result in S6915 is YES, the process proceeds to S6916.

[0184] In S6916, for combinations of targets 6 and moving objects with the same TTC level, the targets 6 are prioritized based on whether the targets 6 and moving objects are on the same road or on different roads. In the example of Fig. 13, the priority of the target 6b, which is on a different road from the other vehicle 5b, is set higher than the priority of the target 6a, which is on the same road as the other vehicle 5c.

[0185] In S6917, it is determined again whether or not there is a target 6 with the same priority. If the determination result in S6917 is NO, the process proceeds to S6919. If the determination result in S6917 is YES, the process proceeds to S6918.

[0186] In S6918, for combinations of target object 6 and moving object with the same priority, priority is assigned based on the length of the space in which the moving object can move in the road width direction. In the example of Fig. 15, within the intersection, the length of free space 7b in the road width direction is shorter than the length of free space 7c in the road width direction. Therefore, the priority of target object 6b, which is predicted to move into the space in which other vehicle 5b, which transmitted free space information indicating free space 7b, can move, is set higher than the priority of target object 6a.

[0187] In S6919, the targets 6 are sorted in the order of priority determined up until the execution of S6919. After the execution of S6919, the process proceeds to S692 in FIG.

[0188] In S692, the object iterator it_obj is set to the top of the sorted list. The iterator indicates the position where processing is to be performed.

[0189] In S693, the next object is obtained from the sorted list, and the object iterator it_obj is incremented by one.

[0190] In S694, a management container for the segment to be generated is generated, which can include the station type, reference position, segmentation information, and the number of recognized objects.

[0191] In S695, POCs (ie, recognized object containers) are generated for all objects up to the current object iterator it_obj.

[0192] In S696, the encoded size of the message generated without the sensor information container is calculated.

[0193] In S697, it is determined whether the size of the encoded message exceeds MTU_CPM. If the determination result in S697 is NO, the process proceeds to S698.

[0194] In S698, it is determined whether there are any more objects in the sorted list. If the determination result in S698 is YES, the process returns to S693. If the determination result in S698 is YES, the process proceeds to S700 in FIG.

[0195] If the determination result in S697 is YES, the process proceeds to S699. In S699, the object iterator it_obj is decremented by 1. Thereafter, the process proceeds to S700 in FIG.

[0196] 22, the size of the encoded message including the sensor information container is calculated. In S701, it is determined whether the size calculated in S700 exceeds MTU_CPM. If the determination result in S701 is YES, the process proceeds to S702.

[0197] In S702, the size of the encoded message without the sensor information container is calculated, and then the process proceeds to S704.

[0198] If the determination result in S701 is NO, the process proceeds to S703. In S703, T_LastSensorInfoContainer is set to T_GenEvent. Thereafter, the process proceeds to S704.

[0199] In S704, the sensor information container and the selected candidate for the recognized object container are combined and saved.

[0200] In S705, it is determined whether there are any more objects in the sorted list. If the determination result in S705 is YES, the process proceeds to S706. In S706, the object iterator it_obj is incremented to the next object. After S706 is executed, the process returns to S693 in FIG. 21.

[0201] If the determination result in S705 is NO, proceed to S707. In S707, it is determined whether the sensor information container is included in a message that has already been sent or the current message. If the determination result in S707 is NO, return to S700 described above. If the determination result in S707 is YES, proceed to S708.

[0202] In S708, a management container is generated for each segment that has been generated so far. In S709, the CPM of each segment is encoded. After the process in FIG. 22 is completed, the process proceeds to S7 in FIG.

[0203] In S7, T_LastCpmtimestamp is set in T_GenEvent. T_LastCpmtimestamp indicates the time when the last CPM was generated.

[0204] In S8, the next CPM is obtained. When S709 is executed, the CPM is each segment encoded in S709. In S9, the CPM obtained in S8 is transmitted.

[0205] In S10, it is determined whether there are any untransmitted CPM segments. If the determination result in S10 is YES, the process returns to S8, where the untransmitted CPM segments are acquired and transmitted. If the determination result in S10 is YES, the process in FIG. 16 ends.

[0206] Summary of the embodiment In the embodiment described above, the V2X communications device 60 includes a prediction unit 66 that predicts whether the target 6 will move into a space in which a moving object can move, based on the target characteristics and free space information. When the prediction unit 66 predicts that the target 6 will move into a space in which a moving object can move, the target information transmission unit 67 prioritizes transmitting target information about the target 6, compared to when the prediction unit 66 does not predict that the target 6 will move into a space in which a moving object can move. Thus, the source V2X communications device 60 can prioritize transmitting target information that is likely to be useful to the V2X communications device 60 that transmitted the CPM including the free space information.

[0207] The prediction unit 66 uses road shape information in addition to the target characteristics and free space information to predict whether the target 6 will move into a space in which the moving object can move. This improves the accuracy of prediction as to whether the target 6 will move into a space in which the moving object can move. This allows the source V2X communication device 60 to preferentially transmit target information that is likely to be useful to the V2X communication device 60 that transmitted the CPM including free space information.

[0208] When the prediction unit 66 predicts that there are multiple targets 6 moving in the space where the moving object can move, the target information transmission unit 67 determines the priority of transmitting target information about the multiple targets 6 based on the TTCs between the multiple targets 6 and the moving object. For example, in the example shown in FIG. 13 , if the TTC between target 6b and another vehicle 5b is 2 seconds and the TTC between target 6a and another vehicle 5c is 3 seconds, the target information transmission unit 67 determines the priority of transmitting target information about target 6b to be higher than the priority of transmitting target information about target 6a. This allows the source V2X communication device 60, which transmitted the CPM including free space information, to transmit target information about targets 6 that require a rapid response, with higher priority.

[0209] Furthermore, if the TTCs between multiple targets 6 and moving objects are the same, the target information transmitter 67 prioritizes a case where the targets 6 and moving objects are on different roads over a case where the targets 6 and moving objects are on the same road. For example, in the example shown in FIG. 13, assume that the TTCs between the target 6a and the other vehicle 5c and the TTCs between the target 6b and the other vehicle 5b are the same. The target 6a and the other vehicle 5c are on the same road, while the target 6b and the other vehicle 5b are on different roads. Therefore, the target information transmitter 67 prioritizes transmitting target information about the target 6b over the priority of transmitting target information about the target 6a.

[0210] For moving bodies such as other vehicles 5b and 5c, it is more difficult to recognize a target 6 that exists on a different road than a target 6 that exists on the same road. Therefore, by doing as described above, the source V2X communication device 60 can preferentially transmit target information about a target 6 that is difficult for the V2X communication device 60 that transmitted the CPM including free space information to recognize.

[0211] Furthermore, the target information transmitter 67 determines the priority based on whether the target 6 and the moving object are on the same road or on different roads. If there are multiple targets 6 with the same priority, the target information transmitter 67 compares the road width lengths of the spaces in which the moving object can move. The transmitter 67 then assigns a higher priority to transmitting target information for a target 6 moving into a space with a shorter road width length. In the example of FIG. 15 , when comparing the road width lengths of the spaces in which the other vehicles 5b and 5c can move, the other vehicle 5b has a shorter road width length. Therefore, the transmitter 67 assigns a higher priority to transmitting target information for the target 6b moving into the space in which the other vehicle 5b can move than the target 6a. This allows the transmitter 6 to preferentially transmit target information for targets 6 for which contact avoidance operations are relatively difficult near points where contact is possible.

[0212] Although the embodiments have been described above, the disclosed technology is not limited to the above-described embodiments, and the following modifications are also included in the scope of the disclosure. Furthermore, various modifications other than those described below can be made without departing from the spirit of the invention.

[0213] <Variation 1> In the embodiment, after prioritizing based on whether or not the target 6 moves into a space where the moving object can move (S6912), the prioritization is further performed based on the following three indices: (1) prioritizing based on the TTC level (S6914), (2) prioritizing based on whether or not the target 6 and the moving object are present on the same road (S6916), and (3) prioritizing based on the length of the space in the road width direction where the moving object can move (S6918).

[0214] However, after prioritizing based on whether or not the target 6 moves into a space where the moving body can move, prioritizing based on the TTC level may be omitted, and prioritizing based on whether or not the target 6 and the moving body are on the same road may be performed.

[0215] <Variation 2> In addition, after prioritizing based on whether or not the target 6 moves into a space in which the moving body can move, prioritizing based on the TTC level and whether or not the target 6 and the moving body are on the same road may be omitted, and prioritizing based on the road width direction length of the space in which the moving body can move may be performed.

[0216] <Variation 3> Also, (1) and (3) may be executed after prioritizing based on whether the target 6 moves into a space where the moving body can move. In other words, after prioritizing based on the TTC level, prioritizing based on whether the target 6 and the moving body are on the same road may be omitted, and prioritizing may be performed based on the length of the movable space in the road width direction.

[0217] <Variation 4> Also, (2) and (3) may be executed after prioritizing based on whether the target 6 moves into a space where the moving body can move. In other words, prioritizing based on the TTC level may be omitted, and prioritizing based on whether the target 6 and the moving body are on the same road may be performed, and then prioritizing based on the length of the movable space in the road width direction may be performed.

[0218] <Variation 5> The V2X communication device 60 is mounted on the vehicle 5. However, the V2X communication device 60 may be fixed to the roadside. That is, the V2X communication device 60 may be an RSU or a part of an RSU.

[0219] <Variation 6> The controller 63 and the methods described herein may be implemented by a special-purpose computer comprising a processor programmed to perform one or more functions embodied in a computer program. Alternatively, the controller 63 and the methods described herein may be implemented by dedicated hardware logic circuitry. Alternatively, the controller 63 and the methods described herein may be implemented by one or more special-purpose computers comprising a processor executing a computer program in combination with one or more hardware logic circuits. Furthermore, the computer program may be stored as instructions executed by a computer on a computer-readable non-transitory storage medium.

Claims

1. A communication device including a target information transmitting unit (67) that wirelessly transmits target information, which is information on a target whose existence has been recognized, a free space information acquisition unit (64) that acquires free space information from the other communication devices mounted on the mobile body; a target characteristic estimation unit (65) for estimating target characteristics including a relative distance and a moving direction of the target; a prediction unit (66) that predicts whether the target will move into a space in which the moving body can move, based on the target characteristics and the free space information, the target information transmitting unit, when the prediction unit predicts that the target will move into a space in which the moving body can move, increases the priority of transmitting the target information about the target compared to when the prediction unit does not predict that the target will move into a space in which the moving body can move; When the prediction unit predicts that the target will move into a space in which the moving body can move for a plurality of combinations of the moving body and the target, the target information transmission unit compares the lengths in the road width direction of the spaces in which the moving body can move, and increases the priority of transmitting the target information for the target moving into the space with a shorter length in the road width direction.

2. A communication device including a target information transmitting unit (67) that wirelessly transmits target information, which is information on a target whose existence has been recognized, a free space information acquisition unit (64) that acquires free space information from the other communication devices mounted on the mobile body; a target characteristic estimation unit (65) for estimating target characteristics including a relative distance and a moving direction of the target; a prediction unit (66) that predicts whether the target will move into a space in which the moving body can move, based on the target characteristics and the free space information, the target information transmitting unit, when the prediction unit predicts that the target will move into a space in which the moving body can move, increases the priority of transmitting the target information about the target compared to when the prediction unit does not predict that the target will move into a space in which the moving body can move; When the prediction unit predicts that there are multiple targets moving into the space within which the moving body can move, the target information transmission unit compares the lengths of the spaces within which the moving body can move in the road width direction if the time to collision between the multiple targets and the moving body is at the same level, and increases the priority of transmitting the target information for the target moving into the space with a shorter length in the road width direction, and increases the priority of transmitting the target information for the target with a shorter time to collision than for the target with a longer time to collision if the time to collision is not at the same level.

3. A communication device including a target information transmitting unit (67) that wirelessly transmits target information, which is information on a target whose existence has been recognized, a free space information acquisition unit (64) that acquires free space information from the other communication devices mounted on the mobile body; a target characteristic estimation unit (65) for estimating target characteristics including a relative distance and a moving direction of the target; a prediction unit (66) that predicts whether the target will move into a space in which the moving body can move, based on the target characteristics and the free space information, the target information transmitting unit, when the prediction unit predicts that the target will move into a space in which the moving body can move, increases the priority of transmitting the target information about the target compared to when the prediction unit does not predict that the target will move into a space in which the moving body can move; When the prediction unit predicts that the target will move into a space in which the moving body can move for a plurality of combinations of the moving body and the target, the target information transmission unit assigns a higher priority to a case in which the target and the moving body are on different roads than a case in which the target and the moving body are on the same road; The target information transmission unit determines the priority based on whether the target and the moving body are on the same road or whether the target and the moving body are on different roads, and if there are multiple targets with the same priority, compares the lengths in the road width direction of the spaces in which the moving bodies can move, and increases the priority of transmitting the target information for the targets moving to the spaces with shorter lengths in the road width direction.

4. 4. A communication device according to claim 1, The prediction unit predicts whether the target will move into a space in which the moving body can move, using road shape information in addition to the target characteristics and the free space information.

5. A communication method for wirelessly transmitting target information, which is information on a target whose presence has been recognized, comprising: Acquiring free space information from a target information communication device mounted on a moving object; estimating target characteristics for the target, including relative range and direction of movement; predicting whether the target will move into a space in which the moving body can move, based on the target characteristics and the free space information; When the target predicts that the moving body will move into a space in which the moving body can move, a higher priority is assigned to transmitting the target information about the target than when the target does not predict that the moving body will move into a space in which the moving body can move; a communication method for predicting that the target will move into a space in which the moving body can move, for a plurality of combinations of the moving body and the target, comparing the lengths of the spaces in which the moving body can move in the road width direction, and increasing the priority of transmitting the target information for the target moving into the space with a shorter length in the road width direction.

6. A communication method for wirelessly transmitting target information, which is information on a target whose presence has been recognized, comprising: Acquiring free space information from a target information communication device mounted on a moving object; estimating target characteristics for the target, including relative range and direction of movement; predicting whether the target will move into a space in which the moving body can move, based on the target characteristics and the free space information; When the target predicts that the moving body will move into a space in which the moving body can move, a higher priority is assigned to transmitting the target information about the target than when the target does not predict that the moving body will move into a space in which the moving body can move; When it is predicted that there are a plurality of targets moving into a space in which the moving body can move, if the time to collision between the plurality of targets and the moving body is at the same level, the lengths in the road width direction of the space in which the moving body can move are compared, and the priority of transmitting the target information for the target moving into the space with a shorter length in the road width direction is increased, and if the time to collision is not at the same level, the priority of transmitting the target information for the target with a shorter time to collision is increased over the target with a longer time to collision.

7. A communication method for wirelessly transmitting target information, which is information on a target whose presence has been recognized, comprising: Acquiring free space information from a target information communication device mounted on a moving object; estimating target characteristics for the target, including relative range and direction of movement; predicting whether the target will move into a space in which the moving body can move, based on the target characteristics and the free space information; When the target predicts that the moving body will move into a space in which the moving body can move, a higher priority is assigned to transmitting the target information about the target than when the target does not predict that the moving body will move into a space in which the moving body can move; For a plurality of combinations of the moving body and the target, when it is predicted that the target will move into a space in which the moving body can move, a case in which the target and the moving body exist on different roads is given a higher priority than a case in which the target and the moving body exist on the same road; A communication method in which, after determining a priority based on whether the target and the moving body are on the same road or whether the target and the moving body are on different roads, if there are multiple targets with the same priority, the lengths of the spaces in which the moving bodies can move in the road width direction are compared, and the priority of transmitting the target information for the target moving to the space with a shorter length in the road width direction is increased.

8. 8. A communication method according to any one of claims 5 to 7, comprising: A communication method that predicts whether the target will move into a space in which the mobile body can move by using road shape information in addition to the target characteristics and the free space information.

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