Communication device, communication system, control method, and program

Abstract

A communication device (200) having a sidelink communication function is provided with: a determination means (201) for determining whether another communication device (20C) and a relay device having a sidelink relay function can communicate with each other; and a communication means (204) for transmitting a message to be transmitted and received between the other communication device (20C) and the relay device (10) in a case where the determination means (201) determines that the other communication device (20C) and the relay device (10) are not able to communicate with each other.

Description

Technical Field

[0001] The present disclosure relates to a communication device, a communication system, a control method, and a program. Background Art

[0002] In recent years, the development of 3GPP (registered trademark) (3rd Generation Partnership Project) LTE (Long Term Evolution) and 5G (NR; New Radio) specifications has been underway. Among them, a standard specification called sidelink communication (hereinafter, referred to as sidelink) is being developed. This specification enables direct wireless communication between devices (UE; user equipment) using an interface called PC5 without the intermediary of a mobile communication network (such as a core network and a base station). NR sidelink communication uses Layer-2 ID (L2ID; sidelink communication identifier) ​​as an identifier representing a transmission source device and a transmission destination device.

[0003] Meanwhile, a system is being provided in which vehicles perform direct wireless communication with each other using side link communication to acquire information about nearby vehicles such as position, speed, and vehicle control information and provide safe driving assistance to the driver as needed.

[0004] In the technology proposed in Patent Document 1, a server acquires position information and speed information about a moving vehicle and stores map information associating the current position of the vehicle with a Layer-2 ID assigned to the vehicle. The vehicles then communicate with each other using the Layer-2 ID based on the map information to exchange information between the vehicles.

[0005] Furthermore, 3GPP (registered trademark) is developing specifications for extending the communication range of side link communication using a relay device (side link relay).

[0006] Patent Document 2 proposes a technology for connecting a terminal (UE) outside the coverage of a base station to a relay device (sidelink relay) installed within the coverage of the base station via sidelink communication to enable communication with the base station.

[0007] Citation List

[0008] Patent Literature

[0009] Patent Document 1: Japanese Patent Application Laid-Open No. 2020-188405

[0010] Patent Document 2: Japanese Patent Application Laid-Open No. 2021-078140 Summary of the invention

[0011] Technical issues

[0012] However, the conventional technology does not disclose a method for extending the communication range by relaying side-link communication.

[0013] An object of the present invention is to provide a communication device or the like which can extend the communication range by relaying side link communication.

[0014] Solution to the problem

[0015] According to one aspect of the present disclosure, a communication device includes the following components, that is, the communication device with a side link communication function includes: a determination component for determining whether another communication device and a relay device with a side link relay function can communicate with each other; and a communication component for transmitting messages to be sent and received between the other communication device and the relay device when the determination component determines that the other communication device and the relay device cannot communicate with each other.

[0016] Advantageous Effects of the Invention

[0017] According to the present disclosure, the communication range can be extended by relaying side link communication. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a diagram illustrating a configuration example of a communication system according to the present disclosure.

[0019] Figure 2 is a block diagram illustrating a functional configuration example of a roadside device.

[0020] Figure 3 is a block diagram illustrating a functional configuration example of a communication device constituted by a vehicle.

[0021] Figure 4 is a block diagram illustrating a hardware configuration example of a roadside device.

[0022] Figure 5 : is a diagram illustrating an example of a data structure of a side link communication message to be exchanged via a roadside device.

[0023] Figure 6 is a flowchart illustrating an example of processing at a roadside device.

[0024] Figure 7 is a flowchart illustrating an example of processing at a communication device constituted by a vehicle.

[0025] Figure 8 is a flowchart illustrating the side link reception process (step S300 ).

[0026] Fig. 9A is a flowchart illustrating the connection request / acceptance transmission process (step S500).

[0027] Fig. 9B is a flowchart illustrating the message transmission process (step S600 ).

[0028] Fig. 10A is a diagram illustrating an example of a communication sequence between a roadside device and a vehicle-mounted terminal.

[0029] Fig. 10B : is a diagram illustrating an example of a communication sequence between a roadside device and a vehicle that does not include a relay process of another vehicle.

[0030] Fig.11 is a diagram illustrating a broadcast communication method.

[0031] Fig.12 It is a diagram illustrating a multicast (groupcast) communication method.

[0032] Fig.13 is a diagram illustrating a unicast communication method.

[0033] Fig.14 is a diagram illustrating an example of a data structure of a discovery message when a terminal (UE) performs direct side link communication. DETAILED DESCRIPTION

[0034] The exemplary embodiments will be described in detail below with reference to the accompanying drawings. Note that the following exemplary embodiments are not intended to limit the invention set forth in the claims. Although the exemplary embodiments describe multiple features, all of the multiple features are not necessarily essential to the invention, and the multiple features can be freely combined. In the accompanying drawings, the same or similar components are represented by the same reference numerals, and repeated descriptions will be omitted.

[0035] Conventionally, when terminals use side link communication without the mediation of a relay device to exchange information, the terminal serving as a UE cannot exchange information until it enters a state where a direct connection with its partner terminal serving as a UE can be established. For example, at locations such as intersections (especially intersections with poor visibility) where radio waves are blocked by the presence of buildings or a large number of vehicles, the communication range will be narrow due to the short range and many blind spots. In view of this, it is desirable to install a roadside device serving as a side link relay to extend the communication range between terminals (UEs) by relaying side link communications addressed to a specific Layer-2 ID.

[0036] However, the presence or absence of a roadside device at an intersection is generally unknown to a terminal, and therefore a relay request to a specified roadside device cannot be issued. Furthermore, a roadside device cannot determine whether to relay a received sidelink message unless it knows the specific Layer-2 ID to be relayed. The following exemplary embodiments address such issues.

[0037] In the following exemplary embodiments, a roadside device set near an intersection for the purpose of exchanging information related to traffic near the intersection is described as an example of a relay device. However, the relay device is not limited to this. The relay device can be set at any installation location, and the communication via the relay device can have any purpose. The relay device can be moved during relaying. The relay device can be installed in a location where a mobile communication network cannot be accessed, such as an environment without coverage of a base station, but can be installed in a location where a mobile communication network can be accessed. The relay device can provide a relay function while connected to a mobile communication network. Multiple relay Layer-2 IDs corresponding to multiple corresponding usage purposes can be set for a single relay device.

[0038] <Exemplary Embodiment>

[0039] [System Configuration]

[0040] Figure 1 1 is a diagram illustrating a configuration example of a communication system according to an exemplary embodiment of the present disclosure. The communication system includes a roadside device 10 (an example of a relay device) installed near an intersection K and vehicles traveling near the intersection K (vehicles 20A to 20E).

[0041] exist Figure 1 In the present invention, the roadside device 10 is a device that has a side link relay function (function as a side link relay) and relays the side link communication by the side link relay function. Figure 1 In the example of FIG. 1 , the roadside device 10 is installed on the roadside near, for example, an intersection K, and communicates with vehicles, pedestrians, etc. The roadside device 10 is particularly suitable for being installed near the intersection K where visibility is poor.

[0042] exist Figure 1 , vehicles 20A to 20E represent vehicles traveling on a road near intersection K. Vehicles 20A to 20E have the function of a sidelink communication device (UE; user equipment) and can perform sidelink communication with an external communication device. Vehicles 20A to 20E acquire information from outside the vehicle through sidelink communication, display the information, and control the vehicle based on the information. Vehicles 20A to 20E can also acquire information about their own vehicles and notify the external device of the information through sidelink communication.

[0043] The roadside device 10 is configured to, upon receiving a message of a relay request from a side link communication device (UE) including vehicles 20A to 20E, resend a message of the same content or a modified message depending on the content of the message. Figure 1 In FIG. 1 , area 10A indicates the communication range of the roadside device 10 .

[0044] The roadside device 10 is assigned Layer-2 ID "RRR" as a side link communication identifier. Vehicles 20A to 20E are assigned corresponding side link communication identifiers, such as Layer-2 ID "AAA", Layer-2 ID "BBB" and Layer-2 ID "CCC". In this exemplary embodiment, in order to use information exchange of side link communication at the intersection, intersection K is also assigned Layer-2 ID "KKK" as a side link communication identifier. In this exemplary embodiment, vehicles and the like are assumed to be UEs that support side link communication. However, this is not restrictive. For example, the UE may include a UE carried by a user (including a tablet terminal and a smart watch) and a UE worn by a user (including a wearable terminal such as a head-mounted display). The UE may also include a car navigation device installed in the vehicle.

[0045] [Functional configuration of the device]

[0046] Next, the functional configuration of the device according to the present exemplary embodiment will be described. The configuration of the functional blocks described below is merely an example. Some (or all) of the described functional blocks may be replaced with other functional blocks that perform similar functions. Some of the functional blocks may be omitted. Additional functional blocks may be added. The single functional block described below may be divided into multiple functional blocks. Multiple functional blocks may be integrated into a single functional block.

[0047] Figure 2 1 is a block diagram illustrating an example of a functional configuration of a roadside device according to the present exemplary embodiment. Figure 2 As shown in , the roadside device 10 includes a control unit 101 , a storage unit 102 , a communication processing unit 103 , a relay processing unit 104 , a wireless communication unit 105 , and a wired communication unit 106 .

[0048] The control unit 101 controls the operation of the roadside device 10 based on a program or the like stored in the storage unit 102 .

[0049] The storage unit 102 stores information used by the control unit 101 for control, programs related to wireless and wired communications, other information, and the like.

[0050] The communication processing unit 103 performs analysis of the side link communication message, etc. For example, the communication processing unit 103 analyzes the received side link communication message to determine its content, generates destination and source information using Layer-2 ID, and generates the content of the side link communication message to be transmitted.

[0051] The relay processing unit 104 performs processing related to the relay of the side link communication sent from other communication devices. For example, the relay processing unit 104 analyzes Layer-2 IDs related to the destination, source, and relay, setting information related to the relay, and the content of the message payload, etc., and determines operations related to the relay.

[0052] The wireless communication unit 105 transmits and receives a signal corresponding to a message or the like to and from an external wireless device via the antenna 105a using side link communication. The wired communication unit 106 connects the roadside device 10 to an external device 31 (such as an external server) via a wired network including the Internet 30, and transmits and receives information to and from the external device 31. For example, the roadside device 10 acquires information from the external device 31 via the wired communication unit 106, and generates a side link message corresponding to the acquired information using the communication processing unit 103. The roadside device 10 can then transmit a signal corresponding to the message via the wireless communication unit 105.

[0053] Figure 3 20A to 20E is a block diagram illustrating a functional configuration example of a communication device configured by vehicles (such as vehicles 20A to 20E) according to the present exemplary embodiment.

[0054] like Figure 3 As shown in , the communication device 200 (an example of a communication device, a first communication device, and a second communication device) includes a control unit 201 (an example of a determination component), a storage unit 202, a communication unit 203, and a wireless communication unit 204 (an example of a communication component). The communication device 200 also includes a vehicle information acquisition unit 205, an operation unit 206, and a display unit 207.

[0055] The control unit 201 controls the operation of the communication device 200 based on a program or the like stored in the storage unit 202. The control unit 201 may be configured as a part of a control device related to the operation of the own vehicle other than the operation of the communication device 200. The control unit 201 may be configured to perform various types of processing in cooperation with the control device.

[0056] The storage unit 202 stores information used by the control unit 201 for control, and information related to wireless and wired communications.

[0057] The communication processing unit 203 performs analysis of the side link communication message, etc. For example, the communication processing unit 203 analyzes the content of the side link communication message received by the wireless communication unit 204, and if the communication is directed to the own device, performs processing corresponding to the content and responds as needed.

[0058] The wireless communication unit 204 transmits and receives information-encoded signals to and from an external wireless device via the antenna 204a using the sidelink communication. The wireless communication unit 204 may also be configured to support communication methods other than the sidelink communication.

[0059] The vehicle information acquisition unit 205 acquires vehicle information about the own vehicle. The vehicle information includes position information about the own vehicle, information to be notified to other vehicles, and other information.

[0060] The operation unit 206 receives operations related to the communication device 200 of the own vehicle.

[0061] The display unit 207 displays information acquired from the outside of the own vehicle through wireless communication, information about the operation of the operation unit 206, and vehicle information acquired via the vehicle information acquisition unit 205. The display unit 207 may be configured as a part of a display device that displays information about the own vehicle in addition to information related to the communication device 200.

[0062] [Hardware Configuration]

[0063] Figure 4 is a block diagram illustrating a hardware configuration example of a roadside device.

[0064] like Figure 4 As shown in FIG. 1 , the roadside device 10 includes a CPU (Central Processing Unit) 11, a ROM (Read Only Memory) 12, a RAM (Random Access Memory) 13, and an auxiliary storage device 14. The roadside device 10 also includes a communication I / F (Interface) 15 and a device I / F (Interface) 16.

[0065] The CPU 11 controls the entire roadside device 10 by using the computer program and data stored in the ROM 12 or the RAM 13 to realize Figure 2 The functions of the roadside device 10 shown in FIG. The roadside device 10 may include one or more pieces of dedicated hardware different from the CPU 11, and at least a portion of the processing of the CPU 11 may be performed by the dedicated hardware. Examples of dedicated hardware include ASIC (Application Specific Integrated Circuit), FPGA (Field Programmable Gate Array), and DSP (Digital Signal Processor).

[0066] The ROM 12 stores programs that do not need to be changed, etc. The RAM 13 temporarily stores programs and data supplied from the auxiliary storage device 14, data supplied from the outside via the communication I / F 15, etc. The auxiliary storage device 14 includes, for example, a hard disk drive, and stores various types of data. Therefore, the CPU 11, the ROM 12, the RAM 13, and the auxiliary storage device 14 function as a so-called computer.

[0067] The communication I / F 15 is used to communicate with an external device. For example, the wireless communication unit 105 ( Figure 2 ) performs wireless communication with an external device using the communication I / F 15. This enables, for example, the roadside device 10 to determine a situation based on information from an external device 31 connected to the Internet 30, and to notify the vehicle and pedestrians of necessary information through side link communication based on the determination.

[0068] The device I / F 16 can be connected to various devices. For example, a display device and an input device for a server administrator to check information managed by the roadside device 10, and a sensor, a camera, etc. mounted on the housing of the roadside device 10 are connected to the device I / F 16. In such a case, for example, the roadside device 10 can determine the conditions of vehicles and pedestrians traveling on the road based on information from the camera and the sensor, and notify the vehicles and pedestrians of necessary information through the side link communication based on the determination.

[0069] The communication device 200 constituted by the vehicles 20A to 20E can also be implemented using a similar hardware configuration. For example, if each of the communication devices 200 constituted by the vehicles 20A to 20E has Figure 4 , then an imaging unit and a vehicle sensor including a mechanism for performing imaging can be connected to the device I / F 16. This enables, for example, vehicles 20A to 20E to determine the conditions of other vehicles and pedestrians traveling on the road based on information from the imaging unit and the sensor, and to notify other vehicles and pedestrians of necessary information through side link communication based on the determination. In the present exemplary embodiment, necessary information is sent to the roadside device 10, and thereby can be notified to other vehicles and pedestrians through side link communication via the relay of the roadside device 10.

[0070] More specifically, examples of the content that the roadside device 10 and the communication device 200 communicate with other devices using side link communication include warning information based on surrounding traffic conditions and future predictions detected from sensors and camera information, as well as sensor data and camera video images. By sending and receiving such information, each vehicle can grasp information about oncoming vehicles not only from the presence or absence of oncoming vehicles at merging points such as intersections K, but also from position and speed information about oncoming vehicles, and can provide driving assistance to the driver. The ability to exchange information with low latency also enables handling of merging sequence control, emergency braking control, etc. Moreover, road traffic information such as accidents, traffic jams, emergency vehicles, engineering vehicles, and abnormally driven vehicles detected by the roadside device 10 and other vehicles, as well as information about the movement of pedestrians and bicycles can be received and known in advance through side link communication for safer driving.

[0071] Furthermore, pedestrians, bicycles, etc. having terminals (UE) having similar functions can be informed in advance of dangerous movements of vehicles near them, etc. This can effectively reduce the risk of being involved in an accident.

[0072] [Processing example]

[0073] In the present exemplary embodiment, the vehicles (vehicles 20A to 20E) send a discovery message including a relay request to the roadside device 10. The roadside device 10 returns a discovery response message indicating relay acceptance in response to the received discovery message including the relay request. By receiving the discovery response message, the vehicles recognize that they have become relay targets of the roadside device 10. The vehicles that have become relay targets can communicate with each other using the roadside device 10 as a relay device.

[0074] Note that a vehicle that is not a relay target can also perform direct side link communication with other vehicles, that is, side link communication without the intervention of the roadside device 10. According to the present exemplary embodiment, once the own vehicle becomes a relay target, it can perform side link communication via the roadside device 10 with vehicles and pedestrians with which direct side link communication cannot be performed due to reasons such as obstruction of radio waves.

[0075] Figure 5 is a diagram illustrating an example of a data structure of a side link communication message to be exchanged via a roadside device. A discovery message including a relay request may be sent using 5G ProSe direct discovery. Moreover, a solicitation message for 5G ProSe UE to network relay discovery may be used for sending. ProSe is an abbreviation for Proximity based Services.

[0076] exist Figure 5 In the data structure, "Source Layer-2 ID" stores the Layer-2 ID of the transmission source of the indication information. For example, if the transmission source is vehicle 20A, then the Layer-2 ID "AAA" is stored. If the transmission source is vehicle 20B, then the Layer-2 ID "BBB" is stored. If the transmission source is vehicle 20C, then the Layer-2 ID "CCC" is stored. "Destination Layer-2 ID" stores the Layer-2 ID of the destination of the indication information. "Relay Layer-2 ID" stores the Layer-2 ID of the device (device with sidelink relay function) that indicates the relay message. For example, if the device that relays the message is a roadside device 10, then the Layer-2 ID "KKK" or "RRR" can be stored. "Relay direction" stores information indicating whether the message is directed to the terminal (UE) or the sidelink relay. "Proxy mode" stores information indicating whether this message can be transmitted through a proxy.

[0077] "Hop Count" stores information about the number of times (hop count) a message has been transmitted. "Proxy Layer-2 ID" stores information indicating a device that has transmitted a message. "Frame Type" stores information indicating the type of message. "Frame Payload" stores the body of information to be exchanged between devices using the message.

[0078] Next, the processing at the roadside device 10 and the vehicles (the vehicles 20A to 20E) will be described.

[0079] Figure 6 is a flowchart illustrating an example of processing at a roadside device.

[0080] exist Figure 6 In step S102, the control unit 101 ( Figure 2 ) performs processing for setting parameters of the side link relay function for the roadside device 10 at the time of installation of the roadside device 10. For example, through this processing, the Layer-2 ID "KKK" assigned to the intersection K is stored in the storage unit 102. This enables the roadside device 10 to relay communications addressed to the Layer-2 ID "KKK". In the present exemplary embodiment, the Layer-2 ID "KKK" corresponds to the relay Layer-2 ID.

[0081] In step S104, the control unit 101 determines whether a side link communication message is received via the wireless communication unit 105. After waiting for an affirmative determination, the process proceeds to step S106.

[0082] In step S106, the control unit 101 determines via the communication processing unit 103 whether the message identified as received in step S104 is a discovery message (relay request message) including a request for relaying by the side link relay function ( Figure 5 ). If the determination is affirmative, the control unit 101 advances the process to step S108. If the determination is negative, the control unit 101 advances the process to step S112.

[0083] In step S108, the control unit 101 sets the intermediate side link relay function. Here, the control unit 101 sets the Layer-2 ID of the transmission source of the discovery message including the relay request identified in step S106 as the relay target of the side link communication via the relay processing unit 104. Moreover, based on the exchange of detailed information, the communication device 200 of the vehicle (vehicles 20A to 20E) also sets parameters related to the side link relay function. This enables the roadside device 10 to relay communications from the transmission source of the discovery message including the relay request. The control unit 101 also stores the effective period information specified by the discovery message. The setting of the side link relay function and the effective period information are stored in the storage unit 102.

[0084] In step S110, the control unit 101 returns a discovery response message indicating relay acceptance to the transmission source of the discovery message via the wireless communication unit 105 (the format of the discovery response message is the same as that of the Figure 5 The format of the discovery message shown in is the same as that of the discovery message shown in ). The control unit 101 advances the process to step S104. The reply destination of the discovery response message is the transmission source ( Figure 5 ). By including the Layer-2 ID “RRR” of the roadside device 10 in the discovery response message, the transmission source of the discovery message can be informed of the information.

[0085] If relaying is not acceptable due to some reasons, the process of step S108 may be omitted, and a message that relaying is not acceptable may be returned to the transmission source of the discovery message.

[0086] As described above, the connection between the transmission source of the discovery message including the relay request and the roadside device 10 is established by communication using the unicast communication method. The unicast communication method will be further described below.

[0087] On the other hand, in step S112, the control unit 101 determines via the communication processing unit 103 whether the effective relay period in the message identified as received in step S104 has passed. The effective period information stored in the storage unit 102 in step S108 is used for this determination. If the determination is affirmative, the control unit 101 advances the process to step S116. If the determination is negative, the control unit 101 advances the process to step S114.

[0088] In step S116, the control unit 101 stops the relay processing for the transmission source of the message identified as received in step S104. The setting of the parameters related to the side link relay function (step S108) is canceled.

[0089] In step S118, the control unit 101 transmits a relay termination completion message indicating that the message relay processing is terminated to the relay requesting vehicles (vehicles 20A to 20E), and advances the process to step S104. The transmission destination of the relay termination completion message is the transmission source included in the message identified as received in step S104.

[0090] On the other hand, in step S114, the control unit 101 determines via the communication processing unit 103 whether the message identified as received in step S104 is a message for requesting the termination of relaying (relay termination request message). If the determination is affirmative, the control unit 101 advances the process to step S116. If the determination is negative, the control unit 101 advances the process to step S120. The relay termination request message may include information about the period until the termination of the relay operation. In this case, the process of step S116 is performed at the timing specified by the relay termination request message.

[0091] In step S120, the control unit 101 determines whether the transmission source indicated by the message identified as received in step S104 is the setting target of the side link relay function in step S108. If the determination is affirmative, the control unit 101 advances the process to step S122. If the determination is negative, the control unit 101 advances the process to step S104.

[0092] In step S122 , the control unit 101 generates a message to be transmitted (relayed) by rewriting necessary information such as the direction of the message recognized as received in step S104 via the relay processing unit 104 .

[0093] If the message identified as received in step S104 corresponds to the message that has been sent in step S124, the processing of steps S122 and S124 can be omitted. In other words, if the message of the same relay request is received multiple times, the processing of steps S122 and S124 can be omitted. This can prevent the same message from being relayed multiple times.

[0094] In step S124, the control unit 101 sends (transmits) the message generated in step S122 as a side link communication message using the wireless communication unit 1055, and advances the processing to step S104. The sending destination (transmission destination) in step S124 may be limited to or may not be limited to the terminal (UE) that is the setting target of the side link relay function in step S108. Messages such as the information exchange message identified as received in step S104 are thereby relayed via the roadside device 10. The information exchange message is a message for exchanging information between vehicles, and includes vehicle information such as vehicle speed, vehicle acceleration, and accelerator position.

[0095] If the determination in step S120 is negative, then the message identified in step S104 as the received message not to be relayed may be returned to the transmission source indicated by the message.

[0096] Figure 720A is a flowchart illustrating an example of processing at a communication device constituted by vehicles (vehicles 20A to 20E). Figure 7 The example indicates that the own vehicle (vehicles 20A to 20E) passes through the intersection K ( Figure 1 ) situation.

[0097] exist Figure 7 In step S202, the control unit 201 ( Figure 3 ) determines whether the own vehicle (vehicles 20A to 20E) is approaching the intersection K based on the information acquired by the vehicle information acquisition unit 205. After waiting for the affirmative determination, the control unit 201 advances the processing to step S204.

[0098] In step S202, for example, the control unit 201 compares the position information acquired by a GPS (Global Positioning System) device or the like installed on the own vehicle with the intersection information stored in the storage unit 102. Based on the result of the comparison between these pieces of information, it can be identified that the own vehicle is approaching the intersection K. Here, the intersection information stores the coordinates of the intersection including the intersection K and the Layer-2 ID assigned to the corresponding intersection (for example, the Layer-2 ID "KKK" assigned to the intersection K) in association with each other. The control unit 201 can identify that the own vehicle is approaching a specific intersection by comparing the position information (coordinates) acquired in real time by the vehicle information acquisition unit 205 with the coordinates of the intersection indicated by the intersection information.

[0099] In step S204 , the control unit 201 performs communication preparation processing to enable side link communication using the Layer-2 ID “KKK” assigned to the intersection K. For example, in step S204 , the Layer-2 ID “KKK” is registered in the storage unit 202 as a communication partner.

[0100] In step S206, the control unit 201 determines whether a relay using the Layer-2 ID "KKK" assigned to the intersection K has been requested to the roadside device 10 (step S208). If the determination is affirmative, the control unit 201 advances the process to step S210. If the determination is negative, the control unit 201 advances the process to step S208.

[0101] In step S208, the control unit 201 sends a relay request discovery message ( Figure 5 ).

[0102] In step S210, the control unit 201 determines whether an event to be relayed and notified by the roadside device 10 has occurred based on the information acquired by the vehicle information acquisition unit 205, etc. If the determination is affirmative, the control unit 201 advances the process to step S212. If the determination is negative, the control unit 201 advances the process to step S220.

[0103] In step S212, the control unit 201 determines whether a discovery response message indicating relay acceptance has been received from the roadside device 10 (the format of the discovery response message is the same as that of the Figure 5 The format of the discovery message shown in FIG. 1 is the same as that of the discovery message shown in FIG. 1 ) and whether the communication device 200 has set parameters related to the side link relay function. The discovery response message indicating the relay acceptance is in step S110 ( Figure 6 ) is a message sent from the roadside device 10. If the determination is affirmative in step S212, the control unit 201 advances the process to step S214. If the determination is negative, the control unit 201 advances the process to step S220.

[0104] In step S214, the control unit 201 transmits a communication message ( ) related to the event that occurred to the terminal as the relay target via the roadside device 10 (side link relay). Figure 7 ). The frame payload of the communication message ( Figure 7 ) describes information indicating that a specific event has occurred, as well as additional information related to the event that occurred.

[0105] In step S220, the control unit 201 determines whether the own vehicle is away from the intersection K based on the information acquired by the vehicle information acquisition unit 205. If the determination is affirmative, the control unit 201 advances the processing to step S222. If the determination is negative, the control unit 201 advances the processing to step S224. In step S220, for example, the control unit 201 can recognize that the own vehicle is away from the intersection K based on the position information acquired by the GPS device or the like mounted on the own vehicle and the intersection information stored in the storage unit 102.

[0106] In step S222, the control unit 201 transmits a message (relay termination request message) for requesting termination of relaying to the roadside device 10 via the communication processing unit 203. The relay termination request message is transmitted in step S114 ( Figure 6 ) is identified as a message received by the roadside device 10. The format of the relay termination request message may be, for example, the same format (data structure) as the format of the discovery message including the relay request ( Figure 5 ). In this case, it is possible to Figure 5The relay mode and the value of the valid period shown in are set to predetermined values ​​to indicate that the message is a relay termination request message.

[0107] On the other hand, in step S224, the control unit 201 determines whether a side link communication message transmitted by another terminal (UE) is received via the wireless communication unit 204. If the determination is positive, the control unit 201 advances the process to the side link reception process (step S300). If the determination is negative, the control unit 201 advances the process to step S206.

[0108] Figure 8 A is a flowchart illustrating the side link reception process (step S300).

[0109] exist Figure 8 In step S302 of A, the control unit 201 determines whether the received side link communication message is a message to be transmitted and received between another terminal device (UE) and the roadside device 10. If the determination is affirmative, the control unit 201 advances the process to step S304. If the determination is negative, the control unit 201 advances the process to step S306.

[0110] In step S304, the control unit 201 determines whether the received side link communication message is a relay request message to the roadside device 10 (side link relay) or an acceptance message for the relay request. If the determination is affirmative, the control unit 201 advances the processing to step S500 (connection request / acceptance transmission processing). If the determination is negative, the control unit 201 advances the processing to step S600 (message transmission processing). If the determination in step S304 is negative, the side link communication message includes an information exchange message for exchanging information between vehicles. The information exchange message may include vehicle information such as vehicle speed, vehicle acceleration, and accelerator position.

[0111] In the present exemplary embodiment, if the determination in step S304 is negative, the process may return without executing step S600 (message transmission process). In such a case, the message to be transmitted by the own vehicle is limited to the relay request message and the acceptance message. The determination in step S304 may be positive only when the received side link communication message is a relay request message to the roadside device 10 (side link relay), and the determination in step S304 may be negative for other messages. In such a case, the message to be transmitted by the own vehicle is limited to the relay request message.

[0112] In step S306, the control unit 201 determines whether the received side link communication message is a message addressed to the own device. If the determination is affirmative, the control unit 201 advances the process to step S308. If the determination is negative, the control unit 201 returns the process. Here, the side link communication message for which the determination in step S306 is affirmative is not limited to the side link communication message via the roadside device 10, and also includes a side link communication message directly sent from other terminals (UE) to the own vehicle.

[0113] In step S308, the control unit 201 performs necessary processing such as analysis of the received side link communication message using the communication processing unit 203, and returns the processing. For example, in step S308, the control unit 201 generates a necessary side link communication message based on the analysis result in step S308, and transmits the generated side link communication message using the wireless communication unit 204. The generated side link communication message is transmitted to the communication devices of other vehicles and pedestrians, or is transmitted to the roadside device 10 (with Layer-2 ID "KKK" as the destination).

[0114] Fig. 9A is a flowchart illustrating the connection request / acceptance transmission process (step S500).

[0115] exist Fig. 9A In step S502, the control unit 201 determines whether the received side link communication message is a message related to the roadside device 10 (side link relay) to which the own device is connected. If the determination is affirmative, the control unit 201 advances the processing to step S504. If the determination is negative, the control unit 201 returns the processing. For example, it can be determined whether the own device is connected to the roadside device 10 (side link relay) based on whether the own vehicle has completed the parameter setting related to the side link relay function (step S108).

[0116] In step S504, the control unit 201 determines whether the received side link communication message is a relay request message for the roadside device 10 (side link relay). If the determination is affirmative, the control unit 201 advances the process to step S506. If the determination is negative, the control unit 201 advances the process to step S508.

[0117] In step S506, the control unit 201 determines whether the received relay request message is set to the transmission permission mode. If the determination is affirmative, the control unit 201 advances the processing to step S510. If the determination is negative, the control unit 201 returns the processing. The transmittability of the relay request message to be determined in step S506 (i.e., whether the transmission permission mode is to be set) can be determined by the transmission source of the relay request message or the roadside device 10 (side link relay). Whether the transmission permission mode is set can be included in the information of the message.

[0118] In step S510, the control unit 201 determines whether the number of hops indicated by the received relay request message is less than or equal to a predetermined number of hops. If the determination is positive, the control unit 201 advances the process to step S512. If the determination is negative, the control unit 201 returns the process.

[0119] In step S512, the control unit 201 waits for a predetermined time. Then, the control unit 201 advances the process to step S514.

[0120] In step S514, the control unit 201 determines whether a connection acceptance or connection rejection message in response to the received relay request message is sent from the roadside device 10 (side link relay) (received by the own device). If the determination is affirmative, the control unit 201 returns the process. If the determination is negative, the control unit 201 advances the process to step S516. In step S516, if the aforementioned connection acceptance or connection rejection message is received by the wireless communication unit 204, the determination is affirmative.

[0121] In step S516 , the control unit 201 transmits the relay request message (the relay request message identified in step S504 ) transmitted from another device to the roadside device 10 using the wireless communication unit 204 (side link relay).

[0122] On the other hand, in step S508, the control unit 201 determines whether the received side link communication message is a connection acceptance message. If the determination is affirmative, the control unit 201 advances the process to step S520. If the determination is negative, the control unit 201 returns the process.

[0123] In step S520, the control unit 201 determines whether the received side link communication is a response (reply) to the relay request message transmitted by the own device to the roadside device 10 (side link relay) in step S516. If the determination is affirmative, the control unit 201 advances the process to step S522. If the determination is negative, the control unit 201 returns the process.

[0124] In step S522, the control unit 201 transmits a response (reply) to the relay request message to the response destination (UE) indicated by the message using the wireless communication unit 204, and returns the process.

[0125] Fig. 9B is a flowchart illustrating the message transmission process (step S600). In the connection request / acceptance transmission process (step S600), a process for relaying communication messages other than the aforementioned relay request and acceptance messages between the roadside device 10 and the terminal UE (vehicles 20A to 20E) is performed.

[0126] exist Fig. 9B In step S602, the control unit 201 determines whether the received side link communication message is a message related to the roadside device 10 (side link relay) to which the own device is connected. If the determination is affirmative, the control unit 201 advances the processing to step S604. If the determination is negative, the control unit 201 returns the processing. For example, it can be determined whether the own device is connected to the roadside device 10 (side link relay) based on whether the own vehicle has completed the parameter setting related to the side link relay function (step S108).

[0127] In step S604, the control unit 201 determines whether the communication is related to the device (UE) whose relay request message the own device transmitted in step S516. If the determination is affirmative, the control unit 201 advances the process to step S606. If the determination is negative, the control unit 201 returns the process.

[0128] In step S606, the control unit 201 determines whether the received side link communication message is set to the transmission permission mode. If the determination is affirmative, the control unit 201 advances the processing to step S608. If the determination is negative, the control unit 201 returns the processing. The transmittability of the message to be determined in step S606 (i.e., whether the transmission permission mode is to be set) can be determined by the transmission source of the message or the roadside device 10 (side link relay). Whether the transmission permission mode is set can be included in the information of the message, the relay request message, or the message in response to the relay request message.

[0129] In step S608, the control unit 201 determines whether the hop count of the received side link communication message is less than or equal to the predetermined hop count. If the determination is positive, the control unit 201 advances the process to step S610. If the determination is negative, the control unit 201 returns the process.

[0130] In step S610, the control unit 201 determines whether the received side link communication message is a message sent from the roadside device 10 (side link relay). If the determination is affirmative, the control unit 201 advances the processing to step S612. If the determination is negative, the control unit 201 advances the processing to step S614. If the source of the received side link communication message is the roadside device 10, the determination in step S610 is affirmative. If the source of the received side link communication message is the device (UE) whose relay request message is transmitted in step S516, the determination in step S610 is negative.

[0131] In step S612, the control unit 201 transmits the received side link communication message to the device (UE) to which the relay request message is transmitted in step S516 using the wireless communication unit 204, and returns the process. If the transmission source of the received side link communication message is the device (UE) to which the relay request message is transmitted in step S516, the control unit 201 can return the process without executing step S612. This can prevent the transmitted side link communication message from being returned to the transmission source itself.

[0132] In step S614, the control unit 201 transmits the received side link communication message to the roadside device 10 using the wireless communication unit 204 (side link relay). The process returns.

[0133] As described above, the execution of both step S612 and step S614 enables message exchange between the device (UE) to which the relay request message is transmitted in step S516 and the roadside device 10 (side link relay). In other words, messages (information exchange messages and other messages) to be sent and received between the two devices can be transmitted bidirectionally. Step S612 or step S614 can be skipped. In such a case, the transmission direction of the message to be transmitted by the own vehicle is limited to one direction.

[0134] In the message transmission process (step S600), it can be determined whether the device (UE) to which the relay request message is transmitted in step S516 and the roadside device 10 (side link relay) can perform direct side link communication therebetween. In such a case, if it is determined that the two devices are capable of performing direct side link communication, the transmission can be terminated. For example, it can be determined here whether there is a response (reply) to the transmission of a message from the device (UE) or the roadside device 10 (side link relay) to which the relay request message is transmitted in step S516. If there is a response (reply) (received by the own vehicle), it can be determined that the two devices are capable of performing direct side link communication. Such a determination can be made by the device (UE) or the roadside device 10 (side link relay) to which the relay request message is transmitted in step S516. In such a case, any one of the devices can notify the message transmitting vehicle (the own vehicle that executes step S600) of the determination result.

[0135] In the message transmission process (step S600), it can be detected that the own device can no longer communicate with the roadside device 10 (sidelink relay) or the communication is terminated. Under such detection, the device (UE) whose relay request message is transmitted in step S516 can be notified of the termination of transmission.

[0136] Fig. 10A 20B is a diagram illustrating an example of a communication sequence between a roadside device and a vehicle through a relay process of another vehicle. The sequence includes a relay process of the vehicle 20B. Fig. 10A The step numbers in Figures 6 to 9B .

[0137] like Fig. 10A As shown in , when the roadside device 10 is installed at the intersection K, the roadside device 10 is provided with a sidelink relay function for relaying a sidelink message of Layer-2 ID "KKK" transmitted to the intersection K. The roadside device 10 is then started (step S102).

[0138] When the vehicle 20A approaches the intersection K, the communication device 200 of the vehicle 20A is set to be able to send and receive side link messages addressed to the Layer-2 ID “KKK” of the intersection K (step S204 ).

[0139] Next, the communication device 200 of the vehicle 20A transmits a discovery message including a relay request addressed to the Layer-2 ID “KKK” of the intersection K to the roadside device 10 (step S208 ).

[0140] The roadside device 10 receiving the discovery message exchanges detailed information with the vehicle 20A and configures the operation setting of the side link relay function using the Layer-2 ID “KKK” of the intersection K. The roadside device 10 then sends a relay accept message as a response to the discovery message (steps 108 to 110 ).

[0141] Similarly, vehicle 20B performs communication preparation using the Layer-2 ID of intersection K when approaching intersection K (step S204). Vehicle 20B then sends a discovery message (connection request) including a relay request addressed to Layer-2 ID "KKK" of intersection K (step S208). The roadside device 10 that receives the discovery message configures the operation settings of the side link relay function using Layer-2 ID "KKK" of intersection K. The roadside device 10 then sends a relay acceptance message as a response to the discovery message (steps S108 to S110).

[0142] The operation so far enables the vehicles 20A and 20B to communicate with each other via the roadside device 10 using the Layer-2 ID “KKK” assigned to the intersection K.

[0143] If an event (notification event) occurs in the vehicle 20B in such a state, the vehicle 20B transmits information (step S214). The information is then relayed to the vehicle 20A through the side link relay function of the roadside device 10 (step S124). If the communication method applied is multicast, the information also reaches the vehicle 20B. The vehicle 20B determines that this is the information it has sent based on the transmission source of the information, etc., and discards or ignores the information. The communication method applied will be described below.

[0144] Furthermore, the vehicle 20C performs communication preparation using the Layer-2 ID of the intersection K when approaching the intersection K (step S204 ). The vehicle 20C transmits a discovery message including a relay request addressed to the Layer-2 ID of the intersection K (step S208 ).

[0145] In this state, the vehicle 20C is approaching the intersection K and cannot communicate directly with the roadside device 10 because the distance is a little too large or the radio waves are blocked. Since the discovery message including the relay request does not reach the roadside device 10, the connection acceptance message from the roadside device 10 is not returned to the vehicle 20C. Meanwhile, the vehicle 20B is traveling between the roadside device 10 and the vehicle 20C and is in a state where side link communication with both the roadside device 10 and the vehicle 20C is possible ( Figure 1 ).exist Figure 1 , the communication range SC of the vehicle 20C does not reach the roadside device 10, and the vehicle 20C is located within the communication range SC.

[0146] The vehicle 20B that has been connected to the side link relay function of the roadside device 10 receives the relay request message (including the discovery message of the relay request) from the vehicle 20C to the roadside device 10, and makes a determination related to the connection acceptance (relay acceptance) message. Specifically, the vehicle 20B determines whether the connection acceptance (relay acceptance) message is returned before a certain time has passed from the relay request (step S514). If the relay request (relay acceptance) message is not returned, the vehicle 20B transmits the relay request message sent from the vehicle 20C to the roadside device 10 (step S516). In this case, the vehicle 20B performs the operations required for the roadside device 10 to start transmission when transmitting the relay request message in step S516, such as storing the Layer-2 address of its own device in the message. The roadside device 10 that receives the transmitted relay request message returns a side link relay connection acceptance message with the Layer-2 ID "KKK" of the intersection to the vehicle 20B (step S110). The vehicle 20B transmits the received side link relay connection acceptance message to the vehicle 20C (step S522).

[0147] The vehicle 20C and the roadside device 10 then exchange detailed information via the vehicle 20B, and configure parameters related to the sidelink relay function (steps S108 , S308 , S614 , and S612 ).

[0148] The operation so far enables the vehicle 20C to communicate not only with the vehicle 20B via the roadside device 10 having the sidelink relay function, but also with the vehicle 20A using the Layer-2 ID “KKK” of the intersection.

[0149] After the transmission of the roadside device 10 starts, an event (notification event) occurs in the vehicle 20C. The vehicle 20C sends information via the roadside device 10 (side link relay) (step S214), and the information is transmitted to the roadside device 10 by the vehicle 20B (step S614). The roadside device 10 also sends the information to the vehicle 20A connected by the side link relay function (step S124). Fig. 10A In the example of , when information about an event (notification event) in the vehicle 20C is transmitted from the roadside device 10 and received by the vehicle 20B, the vehicle 20B does not transmit the information to the vehicle 20C.

[0150] Similarly, if an event (notification event) occurs in the vehicle 20A in such a state, the information transmitted from the vehicle 20A is relayed to the vehicles 20B and 20C through the side link relay function of the roadside device 10 (steps S124 and S614). If the communication method applied is multicast, the information also reaches the vehicle 20A. The vehicle 20A determines that this is the information it has sent, and discards or ignores the information.

[0151] When the relay of the roadside device 10 becomes unnecessary, such as when the vehicle 20A has moved away from the intersection K, the vehicle 20A sends a relay termination request message to the roadside device 10 (step S222). The roadside device 10 receiving the relay termination request message accepts the termination of the relay and sends a relay termination completion message to the vehicle 20A (step S118). The suspension and termination of the relay operation by the side link relay function of the roadside device 10 is performed by the roadside device 10 determining the situation.

[0152] Fig. 10B : is a diagram illustrating an example of a communication sequence between a roadside device and a vehicle in which a relay process of another vehicle is not involved. Fig. 10B The step numbers in Figures 6 to 9B .

[0153] like Fig. 10B As shown in , when the roadside device 10 is installed at an intersection, a side link relay function for relaying a side link message of Layer-2 ID "KKK" sent to the intersection is set for the roadside device 10, and the roadside device 10 is started (step S102).

[0154] When the vehicle 20A approaches the intersection, the communication device 200 of the vehicle 20A is set to be able to send and receive side link messages addressed to the Layer-2 ID “KKK” of the intersection (step S204 ).

[0155] Next, the communication device 200 of the vehicle 20A transmits a discovery message including a relay request addressed to the Layer-2 ID “KKK” of the intersection to the roadside device 10 (step S208 ).

[0156] The roadside device 10 receiving the discovery message exchanges detailed information with the vehicle 20A and configures the operation settings of the sidelink relay function using the Layer-2 ID “KKK” of the intersection. The roadside device 10 then sends a relay acceptance message as a response to the discovery message (steps S108 to S110).

[0157] Similarly, the vehicle 20B performs communication preparation using the Layer-2 ID of the intersection K when approaching the intersection K (step S204), and sends a discovery message (connection request) including a relay request addressed to the Layer-2 ID "KKK" of the intersection (step S208). The roadside device 10 that receives the discovery message configures settings related to the use of the side link relay function through mutual information exchange, and sends an acceptance message (steps S108 to S110).

[0158] The operation so far enables the vehicles 20A and 20B to communicate with each other via the roadside device 10 using the Layer-2 ID “KKK” assigned to the intersection K.

[0159] If an event (notification event) occurs in the vehicle 20B in such a state, the vehicle 20B transmits information (step S214). The information is then relayed to the vehicle 20A through the side link relay function of the roadside device 10 (step S124). If the communication method applied is multicast, the information also reaches the vehicle 20B. The vehicle 20B determines that this is the information it has sent based on the transmission source of the information, etc., and discards or ignores the information. The communication method applied will be described below.

[0160] Furthermore, when the vehicle 20C approaches the intersection K, the roadside device 10 and the communication device 202 of the vehicle 20C perform the aforementioned processing of steps S204, S208 and S110. This enables the vehicles 20A, 20B and 20C to communicate with each other via the roadside device 10 using the Layer-2 ID "KKK" assigned to the intersection K.

[0161] If an event (notification event) occurs in the vehicle 20C in such a state, the vehicle 20C transmits information (step S214). The information is then relayed to the vehicles 20A and 20B by the side link relay function of the roadside device 10 (step S124). If the communication method applied is multicast, the information also reaches the vehicle 20B. The vehicle 20B determines that this is the information it has transmitted itself, and discards or ignores the information.

[0162] Similarly, if an event (notification event) occurs in vehicle 20A in such a state, the information sent from vehicle 20A is relayed to vehicles 20B and 20C through the side link relay function of roadside device 10 (step S124). If the communication method applied is multicast, the information also reaches vehicle 20C. Vehicle 20C determines that this is the information sent by itself, and discards or ignores the information.

[0163] In the present exemplary embodiment, the Layer-2 ID "RRR" as an identifier assigned to the roadside device 10 may also be appropriately used. Using the Layer-2 ID "RRR" as the destination may indicate that the type or function of the communication message is different from when the relay identifier is used. For example, the roadside device 10 and the terminal (EU) receiving the communication message may recognize that the received communication message is not a communication message related to the information exchange at the intersection KKK or that the communication message is a communication message for which no relaying of the roadside device 10 is requested.

[0164] Next, the side link communication method will be described.

[0165] Fig.11 is a diagram illustrating a broadcast communication method, Fig.12 is a diagram illustrating a multicast (groupcast) communication method, and Fig.13 is a diagram illustrating a unicast communication method.

[0166] exist Fig.11 In the case of the "broadcast communication method" shown in , the transmitting and receiving devices set a shared Layer-2 ID as a transmitting destination and a receiving destination, respectively.

[0167] In contrast, Fig.12 and Fig.13 As shown in , in the case of "multicast (groupcast) communication method" and "unicast communication method", the transmitting device sends a relay request with a shared Layer-2 ID as the destination ( Fig.12 and Fig.13 The receiving device with the shared Layer-2 ID responds to it to exchange security information and returns a response to the aforementioned relay request ( Fig.12 and Fig.13 'Connection Request Response' in ), thereby enabling data communication.

[0168] Although any of the communication methods can be applied in the present exemplary embodiment, the aforementioned processing has been described by using the “multicast communication method”.

[0169] By the way, as described above, terminals (UEs) such as vehicles 20A, 20B, and 20C can perform direct side link communication with each other without the relay of the roadside device 10. In other words, direct side link communication coexists with communication using the relay of the roadside device 10. By the way, direct side link communication coexists with communication using the relay of the roadside device 10. Therefore, the same terminal (UE) can receive messages with substantially the same content multiple times, and the processing in such a case is left to the terminal (UE) that has received the message. For example, the second and subsequent messages received with substantially the same content can be discarded or ignored.

[0170] Fig.14 is a diagram illustrating an example of a data structure of a discovery message when a terminal (UE) performs direct side link communication.

[0171] like Fig.14 As shown in , when a terminal (UE) such as vehicles 20A to 20E searches for a terminal (UE) that does not have a relay function, a discovery message to be transmitted does not include information indicating a relay request.

[0172] As described above, according to the aforementioned exemplary embodiment, the terminal (vehicles 20A to 20E; UE) uses a relay request message to request the relay of the side link communication addressed to the specific Layer-2 ID "KKK" assigned to the intersection K. The relay request enables relaying by the roadside device 10. Therefore, even if the existence or non-existence of the roadside device 10 (side link relay) capable of relaying is unknown, the terminal (UE) can issue a relay request. Moreover, the Layer-2 ID of the relay device can be informed to the terminal (UE) from the response to the relay request message. In addition, the roadside device 10 can learn the specific Layer-2 ID to be relayed from the destination information included in the relay request message. The roadside device 10 can thereby relay the side link message addressed to the Layer-2ID "KKK". Therefore, the relay of the side link communication by the roadside device 10 can extend the communication range.

[0173] Moreover, according to the aforementioned exemplary embodiment, even if the roadside device 10 (side link relay) and the terminal (vehicle 20C) cannot communicate directly with each other, the communication range can be extended. More specifically, in such a case, the roadside device 10 (side link relay) and the terminal (vehicle 20C) can send and receive messages through the message transmission of another terminal (vehicle 20B). As a result, in an environment such as an intersection where the side link communication has a short range or there are many blind spots due to the presence of buildings or a large number of vehicles, all terminals (UEs) involved in the intersection, etc. can exchange information.

[0174] <Edit>

[0175] UEs such as vehicles 20A to 20E may be configured so that whether to perform relaying to extend the communication range is set by user operation. In such a case, if relaying is set to be performed, control of transmitting a message addressed to another terminal as described in the aforementioned exemplary embodiment is performed. If relaying is not set to be performed, control of not transmitting a message addressed to another terminal may be controlled. The UE may be configured so that the setting of whether to perform relaying to extend the communication range is switched based on the remaining battery power.

[0176] <Other Exemplary Embodiments>

[0177] The present invention can also be implemented by supplying a program for implementing one or more functions of the aforementioned exemplary embodiments to a system or device via a network or storage medium and reading and executing the program by one or more processors in a computer of the system or device. A circuit (e.g., ASIC) that implements one or more functions can also be used for implementation.

[0178] Moreover, for example, in the aforementioned exemplary embodiment, the wireless access method is NR (New Radio), which is a 5G wireless access method. However, other access methods such as 6G or higher and Wi-Fi may be applied at least in part.

[0179] Sidelink communication is not limited to discovery messages. For example, messages related to direct communication and messages related to V2X communication can be used.

[0180] The invention is not limited to the aforementioned exemplary embodiments, and various modifications and changes can be made without departing from the spirit and scope of the invention. Therefore, the claims are attached to disclose the scope of the invention.

[0181] This application claims the benefit of Japanese Patent Application No. 2022-145756, filed September 14, 2022, which is hereby incorporated by reference herein in its entirety.

[0182] Explanation of symbols

[0183] 10 Roadside devices

[0184] 20A~20E Vehicle

[0185] 101 Control Unit

[0186] 102 Storage Unit

[0187] 103 Communication Processing Unit

[0188] 104 Relay processing unit

[0189] 105 Wireless Communication Unit

[0190] 106 Wired communication unit

[0191] 200 communication devices

[0192] 201 Control unit

[0193] 202 Storage Unit

[0194] 203 Communication Processing Unit

[0195] 204 Wireless Communication Unit

[0196] 205 Vehicle information acquisition unit

[0197] 206 Operation unit

[0198] 207 display units.

Claims

1. A communication device having a side link communication function, the communication device comprising: a determining means for determining whether another communication device and a relay device having a sidelink relay function can communicate with each other; as well as and a communication means for transmitting a message to be sent and received between the another communication device and the relay device in a case where the determination means determines that the another communication device and the relay device cannot communicate with each other.

2. The communication device according to claim 1, wherein: The determination component determines that the other communication device and the relay device cannot communicate with each other when, based on a signal received by the communication component, the transmission of a relay request message from the other communication device to the relay device is identified and then a response message from the relay device to the other communication device in response to the relay request message is not identified.

3. The communication device according to claim 2, wherein: The determination section determines that the another communication device and the relay device cannot communicate with each other when the response message is not recognized even after a predetermined time has passed since transmission of the relay request message from the another communication device to the relay device was recognized.

4. The communication device according to claim 2 or 3, wherein: In a case where the determination means determines that the another communication device and the relay device cannot communicate with each other, the communication means transmits the relay request message to the relay device.

5. The communication device according to any one of claims 2 to 4, wherein: In a case where the determination means determines that the another communication device and the relay device cannot communicate with each other, the communication means transmits the response message to the another communication device.

6. The communication device according to any one of claims 1 to 5, wherein the communication section transfers a message to be transmitted and received between the relay device to which the own communication device is connected and the another communication device.

7. The communication device according to any one of claims 1 to 6, wherein the message transmitted by the communication component comprises an information exchange message.

8. The communication device according to claim 7, wherein the communication section transmits the information exchange message in one or both directions from the other communication device to the relay device and from the relay device to the other communication device.

9. The communication device according to any one of claims 1 to 8, wherein the communication section transmits only a message that the other communication device or the relay device permits transmission and includes information indicating that transmission is permitted.

10. The communication device according to any one of claims 1 to 9, wherein: The communication section terminates the transmission in a case where the another communication device and the relay device are determined to have become able to directly communicate with each other based on a notification from the another communication device or the relay device.

11. The communication device according to any one of claims 1 to 10, wherein: In a case where the communication section and the relay device become unable to communicate with each other, the communication section terminates the transmission and notifies the other device that the transmission is terminated.

12. The communication device according to any one of claims 1 to 11, wherein: In a case where the number of hops of the message received from the another communication device or the relay device exceeds a predetermined number, the communication section does not transmit the message.

13. A control method for a communication device having a side link communication function, the control method comprising: a determining step of determining whether another communication device and a relay device having a sidelink relay function can communicate with each other; as well as a transmitting step of transmitting a message to be sent and received between the another communication device and the relay device in a case where it is determined in the determining step that the another communication device and the relay device cannot communicate with each other.

14. A program for causing a computer of a communication device having a side link communication function to execute: a determining step of determining whether another communication device and a relay device having a sidelink relay function can communicate with each other; and a transmitting step of transmitting a message to be sent and received between the another communication device and the relay device in a case where it is determined in the determining step that the another communication device and the relay device cannot communicate with each other.

15. A communication system comprising: a first communication device, the first communication device having a side link communication function; a second communication device, the second communication device having a side link communication function; as well as a relay device, the relay device having a side link relay function, The first communication device comprises: a determining means for determining whether the second communication device and the relay device can communicate with each other, and The communication means is configured to transfer a message to be sent and received between the second communication device and the relay device in a case where the determination means determines that the second communication device and the relay device cannot communicate with each other.

16. The communication system according to claim 15, wherein the relay device is deployed in association with an intersection, and The first communication device and the second communication device move together with a moving object passing through the intersection.

Images