In-vehicle terminal, base station, wireless communication system, control circuit, storage medium, and relay station selection method

Abstract

An in-vehicle terminal (11) comprises: a V2X communication control unit (41) that controls communication with a neighboring vehicle capable of vehicle-to-vehicle communication; a neighboring vehicle information management unit (42) that manages neighboring vehicle information including position information of the neighboring vehicle and information about a communication status of the vehicle-to-vehicle communication acquired through the vehicle-to-vehicle communication; a V2N communication control unit (44) that performs control to provide a first base station connected via direct communication with information about a second base station that cannot be connected via direct communication, and to request the first base station to provide connected terminal information that is information about the neighboring vehicle connected to the second base station;a relay management unit (46) that selects a relay station, which is the neighboring vehicle, to relay indirect communication with the second base station based on the neighboring vehicle information and the connected terminal information; and a redundant system management unit (45) that manages a connection with the first and second base stations and instructs the relay management unit to perform indirect communication with the second base station when the second base station cannot be connected via direct communication.

Description

Area

[0001] The present disclosure relates to an in-vehicle terminal to be installed on a vehicle, a base station, a wireless communication system, a control circuit, a storage medium, and a relay station selection method. background

[0002] In recent years, communication using a cellular network has been used for various applications. For example, the 3rd Generation Partnership Project (3GPP) (registered trademark), an international standards organization, has investigated multipath transmission to improve the reliability of communication in a cellular network. Multipath transmission aims to improve the reliability of communication by transmitting the same information over multiple paths. A direct session between a base station and a terminal is generally used for such multiple paths.However, a method has been investigated in which, in a case where direct sessions cannot be ensured at the same time, a plurality of sessions are ensured by using a direct session and an indirect session using sidelink communication.

[0003] To improve the reliability of communication over multiple paths in a vehicle subject to remote control, remote monitoring, or similar applications, a method for selecting a relay station for an indirect session is important. Many studies have been conducted to date on relaying communication from a moving terminal in vehicle-to-vehicle communication or similar applications, and many studies have also been conducted on a method for selecting a relay station.For example, as a method for selecting a repeater in vehicle-to-vehicle communication, Patent Literature 1 discloses a technique in which a traveling direction, a traveling speed, and the like of a vehicle are obtained from position information of a neighboring vehicle and a timing of acquiring the position information obtained by vehicle-to-vehicle communication, and a repeater is selected using this information. Reference listPatent literature

[0004] Patent Literature 1: Japanese Patent Application, Publication No. 2009-212753 SummaryTechnical problem

[0005] However, according to the above-mentioned conventional technique, an in-vehicle communication device, which is a communication source installed on a vehicle, selects, as a repeater, an in-vehicle communication device that has a high probability of relaying a communication to an in-vehicle communication device as a communication destination from position information of neighboring vehicles and the like. Therefore, there may be a case where the in-vehicle communication device selected by the in-vehicle communication device as the communication source cannot actually communicate with the in-vehicle communication device as the communication destination, and cannot relay communication between the in-vehicle communication device as the communication source and the in-vehicle communication device as the communication destination, which poses a problem.

[0006] The present disclosure has been made in view of the above, and an object thereof is to provide an in-vehicle terminal capable of improving the accuracy of selecting another in-vehicle terminal capable of relaying communication with a base station. Solution to the problem

[0007] To solve the above-described problem and achieve the object, the present disclosure is an in-vehicle terminal installed on a vehicle and performing wireless communication with a plurality of base stations via a plurality of paths. The in-vehicle terminal includes: a vehicle-to-vehicle communication control unit for controlling communication with a neighboring vehicle located near the vehicle and capable of vehicle-to-vehicle communication; an adjacent-vehicle information management unit for managing neighboring-vehicle information including position information of the neighboring vehicle and information about a communication status of the vehicle-to-vehicle communication acquired through the vehicle-to-vehicle communication;a base station communication control unit for performing control to provide a first base station, which is the base station connected via direct communication, with information about a second base station, which is the base station that cannot be connected via direct communication, and to request the first base station to provide connected terminal information, which is information about the neighboring vehicle connected to the second base station; a relay management unit for maintaining the connected terminal information acquired from the first base station and selecting a relay station, which is the neighboring vehicle, that relays indirect communication with the second base station based on the neighboring vehicle information and the connected terminal information;and a redundant system management unit for managing a connection with the first base station and the second base station and for instructing the relay management unit to perform indirect communication with the second base station when the second base station cannot be connected via direct communication.; Advantageous effects of the invention

[0008] The in-vehicle terminal according to the present disclosure achieves the effect of being able to improve the accuracy of selecting another in-vehicle terminal that can relay communication with a base station. Brief description of the drawings Fig. 1 is a diagram showing an exemplary configuration of a wireless communication system according to a first embodiment. Fig. 2 is a block diagram showing an exemplary configuration of an in-vehicle terminal according to the first embodiment. Fig. 3 is a diagram showing an example of adjacent vehicle information managed by an adjacent vehicle information management unit of the in-vehicle terminal according to the first embodiment. Fig. 4 is a sequence diagram illustrating a process in which a vehicle having the in-vehicle terminal according to the first embodiment installed thereon acquires connected terminal information of a base station 31 via a base station 30. Fig. 5 is a block diagram showing an exemplary configuration of the base station according to the first embodiment. Fig. 6 is a diagram showing an exemplary configuration of a processing circuit in a case where the processing circuit realizing the in-vehicle terminal according to the first embodiment is realized by a processor and a memory. Fig. 7 is a diagram showing an example of a processing circuit in a case where the processing circuit realizing the in-vehicle terminal according to the first embodiment is configured with dedicated hardware. Fig. 8 is a block diagram showing an exemplary configuration of an in-vehicle terminal according to a second embodiment. Fig. 9 is a block diagram showing an exemplary configuration of a base station according to the second embodiment. Fig. 10 is a diagram illustrating an example of a process in which the in-vehicle terminal installed in the vehicle selects a relay station in a wireless communication system according to the second embodiment. Fig. 11 is a block diagram showing an exemplary configuration of a base station according to a third embodiment. Fig. 12 is a sequence diagram illustrating a process in which the vehicle having the in-vehicle terminal according to the third embodiment installed thereon acquires connected terminal information and relay station candidate information of a base station 31 via a base station 30. Fig. 13 is a diagram showing an example of adjacent vehicle information managed by the adjacent vehicle information management unit of the in-vehicle terminal according to a fourth embodiment. Description of embodiments

[0009] Hereinafter, an in-vehicle terminal, a base station, a wireless communication system, a control circuit, a storage medium, and a relay station selection method according to each embodiment of the present disclosure will be described in detail with reference to the drawings. First embodiment.

[0010] Fig. Fig. 1 is a diagram showing an exemplary configuration of a wireless communication system 1 according to a first embodiment. The wireless communication system 1 includes a vehicle 10, neighboring vehicles 20 to 22 near the vehicle 10, base stations 30 and 31, and roadside devices 70 to 72. Fig. The wireless communication system 1 shown in Figure 1 assumes a case where the vehicle 10 performs wireless communication with the base stations 30 and 31 via a plurality of paths. The vehicle 10 does not need to use an indirect session if wireless communication with the base stations 30 and 31 can be performed and a plurality of direct sessions can be ensured, but uses an indirect session if a plurality of direct sessions cannot be ensured. As shown in Fig. As shown in Figure 1, the vehicle 10 is in a situation where a direct session has been established with the base station 30, but a direct session cannot be established with the base station 31. Therefore, to establish an indirect session with the base station 31, the vehicle 10 selects a relay station from among the neighboring vehicles 20 to 22 to relay the communication between the vehicle 10 and the base station 31. Consequently, with a direct session and an indirect session, the vehicle 10 can ensure redundant lines and perform highly reliable communication.

[0011] In the following description, the neighboring vehicles 20 to 22 may each be simply referred to as a neighboring vehicle if they are not distinguished from each other, the base stations 30 and 31 may each be simply referred to as a base station if they are not distinguished from each other, and the roadside devices 70 to 72 may each be simply referred to as a roadside device if they are not distinguished from each other. Furthermore, in the following description, the direct session may be referred to as a direct connection and the indirect session as an indirect connection. In the example in Fig. 1, the wireless communication system 1 comprises three adjacent vehicles, two base stations and three roadside devices, but may also comprise four or more adjacent vehicles, three or more base stations and four or more roadside devices. Although in Fig. 1 illustrates only the neighboring vehicles 20 to 22 present in the traveling direction of the vehicle 10 as an example of the wireless communication system 1. The vehicle 10 may also select a neighboring vehicle (not shown) present behind the vehicle 10 in the traveling direction as a relay station in the indirect session with the base station 31. The vehicle 10 may also select a roadside device installed along a road on which the vehicle 10 is traveling as a relay station for the indirect session with the base station 31. The same applies to the following embodiments.

[0012] In the first embodiment, the vehicle 10 and the adjacent vehicles 20 to 22 each comprise an in-vehicle terminal 11. In the example in Fig. 1, the vehicle 10 and the neighboring vehicles 20 to 22 include the same type of in-vehicle terminals 11. However, as long as the operations described later can be performed, the in-vehicle terminals 11 installed on the vehicle 10 and the neighboring vehicles 20 to 22 may have partially different configurations, functions, and the like depending on the manufacturer, vehicle type, and the like of the vehicle 10 and the neighboring vehicles 20 to 22. A case will be described below in which the vehicle 10 and the neighboring vehicles 20 to 22 have in-vehicle terminals 11 of the same type as in Fig. 1 shown.

[0013] The configuration and operation of the in-vehicle terminal 11 are described below. Fig. 2 is a block diagram showing an exemplary configuration of the in-vehicle terminal 11 according to the first embodiment. The in-vehicle terminal 11 includes a vehicle-to-everything (V2X) communication unit 40, a V2X communication control unit 41, a neighboring vehicle information management unit 42, a vehicle-to-network (V2N) communication unit 43, a V2N communication control unit 44, a redundant system management unit 45, and a relay management unit 46. The relay management unit 46 includes a relay station candidate selection unit 47, a relay control unit 48, and a connected terminal information retention unit 49. Note that the example in Fig. 2 does not represent a configuration related to general communication of V2X communication, such as basic safety message (BSM) communication not directly involved in an indirect session establishment process, a configuration related to general communication of V2N communication, and the like. The following describes an operation of the in-vehicle terminal 11 installed on the vehicle 10 and performing wireless communication with a plurality of base stations via a plurality of paths.

[0014] The in-vehicle terminal 11 installed on the vehicle 10 exchanges BSMs and the like with the in-vehicle terminals 11 installed on the neighboring vehicles 20 to 22 via the V2X communication unit 40 and the V2X communication control unit 41 through V2X communication, that is, vehicle-to-vehicle communication. As described above, the in-vehicle terminal 11 installed on the vehicle 10 performs V2X communication with the in-vehicle terminals 11 installed on the neighboring vehicles 20 to 22. However, for the sake of simplicity, the above may be described below, for example, as follows: the vehicle 10 performs V2X communication with the neighboring vehicles 20 to 22; or the in-vehicle terminal 11 performs V2X communication with the neighboring vehicles 20 to 22.

[0015] The V2X communication unit 40 is a vehicle-to-vehicle communication unit that performs V2X communication with the neighboring vehicles 20 to 22 located in the vicinity of the vehicle 10 and capable of V2X communication.

[0016] The V2X communication control unit 41 is a vehicle-to-vehicle communication control unit that controls communication with the neighboring vehicles 20 to 22 that are located near the vehicle 10 and are capable of V2X communication.

[0017] The adjacent-vehicle information management unit 42 manages adjacent-vehicle information including position information of adjacent vehicles and the like, and information about a communication status of the V2X communication, each acquired through the V2X communication from the V2X communication unit 40 and the V2X communication control unit 41. That is, the adjacent vehicles managed by the adjacent-vehicle information management unit 42 as the adjacent-vehicle information include, in addition to the adjacent vehicles 20 to 22, the roadside devices 70 to 72 and the like described above.

[0018] Fig. 3 is a diagram showing an example of the neighboring vehicle information managed by the neighboring vehicle information management unit 42 of the in-vehicle terminal 11 according to the first embodiment. The neighboring vehicle information management unit 42 manages the neighboring vehicle information in a table format as shown in Fig. 3. In Fig. 3, a vehicle identifier (ID) is identification information for identifying a neighboring vehicle. Position data is information indicating a current position of a neighboring vehicle. Time is information indicating a time at which the neighboring vehicle information was acquired from a corresponding neighboring vehicle. The received signal strength indicator (RSSI) is communication quality information indicating the communication status of V2X communication with a neighboring vehicle with a corresponding vehicle ID, and here, the received signal strength is given as an example. One cycle before is communication quality information indicating a previous communication status of V2X communication with a neighboring vehicle with a corresponding vehicle ID.Two cycles prior is communication quality information, indicating a second previous communication status of the V2X communication with a neighboring vehicle with a corresponding vehicle ID. The communication quality information is not limited to the received RSSI; it can also include an error rate, signal-to-noise ratio (SNR), or similar.

[0019] It should be noted that the Fig. 3 is an example, and the adjacent vehicle information management unit 42 may also manage information such as a vehicle type and a traveling speed of each adjacent vehicle as the adjacent vehicle information, as long as the information is acquired through V2X communication. Furthermore, the adjacent vehicle information management unit 42 may perform management such that an adjacent vehicle having a more favorable communication status and a more stable communication quality of the V2X communication in the last prescribed period is placed closer to the top of the table. For example, the adjacent vehicle information management unit 42 performs management such that an adjacent vehicle whose three previously received RSSIs are the highest and most stable is placed at the top. "Stable" here means, for example,a fluctuation in the received RSSIs is the smallest and exceeds a predetermined threshold. Furthermore, the adjacent vehicle information management unit 42 can obtain an adjacent vehicle predicted to be traveling on the same road as the vehicle 10, an adjacent vehicle with a relative speed close to the vehicle 10, and the like from a transition in the latest position information, and manage the adjacent vehicle information taking these items into account.

[0020] The in-vehicle terminal 11 installed on the vehicle 10 performs wireless communication with the base station via the V2N communication unit 43 and the V2N communication control unit 44 in parallel with the V2X communication. By establishing multiple sessions, the wireless communication between the in-vehicle terminal 11 installed on the vehicle 10 and the base station is used for communication for applications such as remote control and remote monitoring that require highly reliable communication. Furthermore, the wireless communication between the in-vehicle terminal 11 installed on the vehicle 10 and the base station is used for communication of services via a cellular network, such as collecting position information and route information of the vehicle 10 and providing traffic jam information and peripheral information by the base station.As described above, the in-vehicle terminal 11 installed on the vehicle 10 performs wireless communication with the base station. However, for convenience, the above may be described below, for example, as follows: The vehicle 10 performs wireless communication with the base station.

[0021] The V2N communication unit 43 is a base station communication unit that performs wireless communication with a base station, ie in the example in Fig. 1 with base station 30, with which a direct session was established.

[0022] The V2N communication control unit 44 is a base station communication control unit that performs wireless communication with a base station, ie in the example in Fig. 1 with the base station 30 with which a direct session has been established. Furthermore, the V2N communication control unit 44, under the control of the redundant system management unit 45, performs control to provide the base station 30 connected via the direct session with information about the base station 31 that cannot be connected via the direct session, and to request the base station 30 to provide connected terminal information, which is information about neighboring vehicles connected to the base station 31. In the following description, the base station 30 may be referred to as the first base station, and the base station 31 may be referred to as the second base station.

[0023] The redundant system management unit 45 manages a plurality of sessions with the base stations. The redundant system management unit 45 manages a plurality of sessions so that the plurality of sessions can be established at any time. In a case where a direct session cannot be established, the redundant system management unit 45 performs control, such as switching to an indirect session or retrying the establishment through the direct session. For example, if the direct session with the base station 31 cannot be established, as shown in Fig. 1, the redundant system management unit 45 instructs the relay management unit 46 to perform switching to the indirect session. At this time, the redundant system management unit 45 notifies the base station 30, via the V2N communication control unit 44 and the V2N communication unit 43, that the direct session with the base station 31 cannot be established, that is, the connection with the base station 31 is broken, and requests the connected terminal information, that is, information about the neighboring vehicles connected to the base station 31.It should be noted that in a case where the base station 30 is to request the base station 31 for the connected terminal information when it is notified by the vehicle 10 of the failure of the connection to the base station 31, the redundant system management unit 45 only needs to inform the base station 30 of the failure of the connection to the base station 31. The connected terminal information, which is information about the neighboring vehicles connected to the base station 31, is identification information of neighboring vehicles, roadside devices, and the like connected to the base station 31, and may include position information of the neighboring vehicles, roadside devices, and the like connected to the base station 31. The identification information is, for example,a vehicle ID, but other information may also be used as long as the information can identify the neighboring vehicles, the roadside facilities, etc. As described above, the redundant system management unit 45 manages the connection to the base station 30 and the base station 31, and instructs the relay management unit 46 to perform the indirect session with the base station 31 when the base station 31 cannot be connected via the direct session.

[0024] When the redundant system management unit 45 instructs the relay management unit 46 to perform the switching to the indirect session, the connected terminal information holding unit 49 acquires the connected terminal information, which is information about the neighboring vehicles connected to the base station 31, from the base station 30 via the V2N communication unit 43 and the V2N communication control unit 44, and holds the connected terminal information.

[0025] The relay station candidate selection unit 47 acquires the neighboring vehicle information from the neighboring vehicle information management unit 42, acquires the connected terminal information from the connected terminal information holding unit 49, and selects a candidate for a relay station to be used for the indirect session with the base station 31 based on the neighboring vehicle information and the connected terminal information. In the case of selecting the candidate for the relay station, the relay station candidate selection unit 47 selects, for example, a neighboring vehicle located at the top of the Fig. 3, and in a case where the selected neighboring vehicle is also included in the connected terminal information acquired by the connected terminal information holding unit 49, the selected neighboring vehicle is set as a relay station candidate. The relay station candidate selection unit 47 outputs the selected relay station candidate to the relay control unit 48.

[0026] The relay control unit 48 instructs the V2X communication control unit 41 to start communication of a relay request to the neighboring vehicle that is the candidate for the relay station selected by the relay station candidate selection unit 47.

[0027] The V2X communication control unit 41, via the V2X communication unit 40, sends a relay request to the neighboring vehicle designated by the relay control unit 48 as a candidate relay station. If the relay request is established, the V2X communication control unit 41 establishes the indirect session with the base station 31 using the neighboring vehicle to which the relay request was sent as the relay station and starts wireless communication with the base station 31. If the relay request is not established, the V2X communication control unit 41 notifies the relay control unit 48 that the relay request has not been established. The relay control unit 48 notifies the relay station candidate selection unit 47 that the relay request has not been established.The relay station candidate selection unit 47 selects a candidate for a next relay station to be used for the indirect session with the base station 31 based on the neighboring vehicle information and the connected terminal information. The in-vehicle terminal 11 repeats the above-described process until the indirect session with the base station 31 is established. As described above, the relay management unit 46 in the in-vehicle terminal 11 maintains the connected terminal information, which is information about the neighboring vehicles connected to the base station 31 acquired from the base station 30, and selects a relay station that is a neighboring vehicle to relay the indirect session with the base station 31 based on the neighboring vehicle information and the connected terminal information.

[0028] Fig. 4 is a sequence diagram illustrating a process in which the vehicle 10 having the in-vehicle terminal 11 according to the first embodiment installed thereon acquires the connected terminal information of the base station 31 via the base station 30. When the direct session with the base station 31 is disrupted (step S100), the vehicle 10 notifies the base station 30 of the disruption in connection with the base station 31 (step S101). Assuming that the base station 30 should request the base station 31 for the connected terminal information when notified from the vehicle 10 of the disruption in connection with the base station 31 as described above, the vehicle 10 only notifies the base station 30 of the disruption in connection with the base station 31.When the vehicle 10 reports the connection failure to the base station 31, the base station 30 requests the connected terminal information, that is, information about the neighboring vehicles connected to the base station 31, from the base station 31 (step S102). The base station 31 provides the connected terminal information, that is, information about the neighboring vehicles connected to the base station 31, to the base station 30 (step S103). When the connected terminal information, which is information about the neighboring vehicles connected to the base station 31, is provided from the base station 31, the base station 30 provides the vehicle 10 with the connected terminal information, which is information about the neighboring vehicles connected to the base station 31 (step S104).Upon acquiring the connected terminal information, which is information about the neighboring vehicles connected to the base station 31, from the base station 30, the vehicle 10 selects a candidate relay station to be used for the indirect session with the base station 31 based on the neighboring vehicle information and the connected terminal information (step S105), and requests the selected relay station to relay to the base station 31 in the indirect session (step S106).

[0029] The following describes a configuration and operation of base stations 30 and 31. Base stations 30 and 31 are base stations in wireless communication system 1, in which vehicle 10 having in-vehicle terminal 11 installed thereon wirelessly communicates with the plurality of base stations 30 and 31 via a plurality of paths. Note that base stations 30 and 31 have similar configurations, and therefore base station 31 is described here as an example. Fig. 5 is a block diagram showing an exemplary configuration of the base station 31 according to the first embodiment. The base station 31 includes a communication unit 60, a communication control unit 61, and a connected terminal information acquisition unit 62.

[0030] The communication unit 60 performs wireless communication with the neighboring vehicles 20 to 22. Furthermore, the communication unit 60 communicates with the base station 30, which is another base station. The communication between the base station 31 and the base station 30 can be wired communication or wireless communication. Here, the communication unit 60 performs wireless communication with the neighboring vehicles 20 to 22 and communication with the base station 30. However, the base station 31 may have two communication units, one of which can perform wireless communication with the neighboring vehicles 20 to 22, and the other of which can perform communication with the base station 30.

[0031] The communication control unit 61 controls the wireless communication with the neighboring vehicles 20 to 22 and the communication with the base station 30 as another base station, and performs control to provide the connected terminal information to the base station 30 as another base station when there is a request from the base station 30 as another base station.

[0032] The connected terminal information acquisition unit 62 acquires identification information of the neighboring vehicles 20 to 22 with which the wireless communication is performed, and maintains the identification information as the connected terminal information.

[0033] That is, in the case of the base station 31, the connected terminal information acquisition unit 62 maintains connected terminal information, which is information about the neighboring vehicles 20 to 22 connected to the base station 31, and the communication control unit 61 performs control to provide the connected terminal information to the base station 30 when there is a request from the base station 30. That is, in the case of the base station 30, the connected terminal information acquisition unit 62 maintains connected terminal information, which is information about the vehicle 10 connected to the base station 30, and the communication control unit 61 performs control to provide the connected terminal information to the base station 31 when there is a request from the base station 31.

[0034] For example, in a case where the wireless communication system 1 is implemented with the 3GPP specification, the adjacent-vehicle information management unit 42 of the in-vehicle terminal 11 collects parameters of a neighboring vehicle with the 3GPP specification, that is, the in-vehicle terminal 11, as adjacent-vehicle information, for example, through vehicle-to-vehicle communication or vehicle-to-infrastructure communication via PC5. The connected-terminal information acquisition unit 62 of the base station is installed in an external application server (application function (AF)) and manages connected-terminal information. It is also possible for the base station to accept a request from the in-vehicle terminal 11 to establish an indirect session with another base station in the direct session and start an indirect session process with the request from the in-vehicle terminal 11 as a trigger.From here, instead of monitoring, the in-vehicle terminal 11 uses the results of the communication conducted so far via a PC5 interface and acquires connected terminal information from the connected base station, which is a list of the in-vehicle terminals 11 connected to the desired base station. In the connected terminal information, each in-vehicle terminal 11 is expressed, for example, by a relay station number. The in-vehicle terminal 11 selects a relay station using the adjacent vehicle information managed by the adjacent vehicle information management unit 42 and the connected terminal information acquired from the connected base station.

[0035] Next, a hardware configuration of the in-vehicle terminal 11 will be described. In the in-vehicle terminal 11, the V2X communication unit 40 and the V2N communication unit 43 are communication devices. The V2X communication control unit 41, the adjacent-vehicle information management unit 42, the V2N communication control unit 44, the redundant system management unit 45, and the relay management unit 46 are implemented by a processing circuit. The processing circuit may be a processor that executes a program stored in a memory or may be dedicated hardware. The processing circuit is also referred to as a control circuit.

[0036] Fig. Fig. 6 is a diagram showing an exemplary configuration of a processing circuit 90 in a case where the processing circuit implementing the in-vehicle terminal 11 according to the first embodiment is implemented by a processor 91 and a memory 92. Fig. The processing circuit 90 shown in Figure 6 is a control circuit and includes the processor 91 and the RAM 92. In a case where the processing circuit 90 is composed of the processor 91 and the RAM 92, the functions of the processing circuit 90 are implemented by software, firmware, or a combination of software and firmware. The software or firmware is described as a program and stored in the RAM 92. In the processing circuit 90, the processor 91 reads and executes the program stored in the RAM 92, thereby realizing the functions. That is, the processing circuit 90 includes the RAM 92 for storing a program, as a result of which a process of the in-vehicle terminal 11 is executed.It can be stated that this program is a program that causes the in-vehicle terminal 11 to execute the functions realized by the processing circuit 90. This program may be provided through a storage medium on which the program is stored or in another way, e.g., through a communication medium.

[0037] It can also be noted that the above program is a program that causes the in-vehicle terminal 11 to execute: a first step, performed by the V2X communication control unit 41, of controlling communication with the neighboring vehicles 20 to 22 that are located near the vehicle 10 and capable of inter-vehicle communication; a second step, performed by the neighboring vehicle information management unit 42, of managing the neighboring vehicle information including the position information of the neighboring vehicles 20 to 22 and the communication status information of the V2X communication, each acquired through the V2X communication;a third step, performed by the V2N communication control unit 44, of performing control to provide a first base station, which is the base station 30 connected via direct communication, with information about a second base station, which is the base station 31 that cannot be connected via direct communication, and to request the first base station to provide connected terminal information, which is information about the neighboring vehicles connected to the second base station; a fourth step, performed by the relay management unit 46, of retaining the connected terminal information acquired from the first base station and selecting a relay station, which is a neighboring vehicle, that relays indirect communication with the second base station based on the neighboring vehicle information and the connected terminal information;and a fifth step, performed by the redundant system management unit 45, of managing a connection with the first base station and the second base station and instructing the relay management unit 46 to perform indirect communication with the second base station when the second base station cannot be connected via direct communication.;

[0038] Here, the processor 91 is a central processing unit (CPU), a processing device, an arithmetic device, a microprocessor, a microcomputer, or a digital signal processor (DSP). The working memory 92 is, for example, a non-volatile or volatile semiconductor memory such as a random access memory (RAM), a read-only memory (ROM), a flash memory, an erasable programmable ROM (EPROM), or an electrical EPROM (EEPROM (registered trademark)), a magnetic disk, a flexible disk, an optical disk, a compact disc, a mini-disk, or a digital versatile disc (DVD).

[0039] Fig. Fig. 7 is a diagram showing an example of a processing circuit 93 in a case where the processing circuit implementing the in-vehicle terminal 11 according to the first embodiment is configured with dedicated hardware. Fig. The processing circuit 93 illustrated in Figure 7 corresponds, for example, to a single circuit, a compound circuit, a programmed processor, a parallel programmed processor, an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or a combination thereof. Part of the processing circuit may be implemented by dedicated hardware and another part by software or firmware. Thus, the processing circuit may implement any of the functions described above by dedicated hardware, software, firmware, or a combination thereof.

[0040] The hardware configuration of the in-vehicle terminal 11 has been described. The hardware configuration of the base station is similar. In the base station, the communication unit 60 is a communication device. The communication control unit 61 and the connected terminal information acquisition unit 62 are implemented by a processing circuit. The processing circuit may be a processor that executes a program stored in a memory or may be dedicated hardware.

[0041] As described above, according to the present embodiment, when selecting a relay station to be used for establishing the indirect session, the in-vehicle terminal 11 installed on the vehicle 10 acquires the connected terminal information, that is, information about the neighboring vehicles connected to the base station to which connection is desired via the base station with which the direct session is established, and selects the relay station using the connected terminal information. Consequently, the in-vehicle terminal 11 can improve the accuracy in selecting another in-vehicle terminal, that is, a neighboring vehicle that can relay communication with the base station. Since the in-vehicle terminal 11 no longer requires V2X communication to search for the candidate relay station, a time until establishing the indirect session can be shortened.

[0042] It should be noted that in the first embodiment, the case was described that the vehicle 10 performing the multi-path communication establishes the indirect session with the base station 31, but the neighboring vehicles 20 to 22 can also perform the multi-path communication in a similar manner. Fig. For example, the neighboring vehicle 21 shown in Figure 1 has established a direct session with the base station 31 and can therefore perform multipath communication by establishing an indirect session with the base station 30 using the vehicle 10 as a relay station. In this case, the neighboring vehicle 21 performs an operation with the base station 31 that is similar to the operation between the vehicle 10 and the base station 30 described above. Second embodiment.

[0043] In the first embodiment, the in-vehicle terminal 11 selects the relay station by using the neighboring vehicle information resulting from the V2X communication and the connected terminal information, which is information about the neighboring vehicles connected to the base station as the destination of the indirect session, obtained via the base station connected in the direct session. In a second embodiment, a method is described in which an in-vehicle terminal selects a relay station to achieve more stable communication by further using position information of neighboring vehicles connected to a base station as the destination of an indirect session obtained via a base station connected in a direct session.

[0044] Fig. Fig. 8 is a block diagram showing an exemplary configuration of an in-vehicle terminal 11a according to the second embodiment. The in-vehicle terminal 11a is obtained by replacing the relay management unit 46 in the in-vehicle terminal 11 of the embodiment shown in Fig. 2, with a relay management unit 46a. The relay management unit 46a is formed by adding a communication area calculation unit 50 to the relay management unit 46 of the embodiment shown in Fig. 2. In the second embodiment, the connected terminal information that the in-vehicle terminal 11a acquires from a base station 30a to be described later includes, in addition to the information described in the first embodiment, position information about neighboring vehicles connected to a base station 31a to be described later.

[0045] The connected terminal information holding unit 49 acquires connected terminal information, that is, information about the neighboring vehicles connected to the base station 31a and including position information of the neighboring vehicles, from the base station 30a via the V2N communication unit 43 and the V2N communication control unit 44, and holds the connected terminal information.

[0046] The communication area calculation unit 50 acquires the connected terminal information from the connected terminal information maintaining unit 49 and determines a communication area of ​​the base station 31a based on the position information of the neighboring vehicles connected to the base station 31a included in the connected terminal information.

[0047] The relay station candidate selection unit 47 acquires the adjacent vehicle information from the adjacent vehicle information management unit 42, acquires the connected terminal information and the communication area calculated by the communication area calculation unit 50 from the communication area calculation unit 50, and selects a candidate relay station to be used for an indirect session with the base station 31a based on the adjacent vehicle information, the connected terminal information, and the communication area.

[0048] Note that the operation of the relay control unit 48 is similar to that of the first embodiment. As described above in the second embodiment, the relay management unit 46a calculates the communication area of ​​the base station 31a based on the connected terminal information and selects the relay station by further using the communication area of ​​the second base station 31a.

[0049] The following describes the configuration and operation of base stations 30a and 31a. Note that base stations 30a and 31a have similar configurations, and therefore base station 31a is described here as an example. Fig. Fig. 9 is a block diagram showing an exemplary configuration of the base station 31a according to the second embodiment. The base station 31a is constructed by adding a terminal position information acquisition unit 63 to the base station 31 of the second embodiment. Fig. 5 shown first embodiment.

[0050] The terminal position information acquisition unit 63 acquires and maintains position information of neighboring vehicles with which the base station 31a performs wireless communication.

[0051] In a case where there is a request from one of the base stations 30a as another base station, the communication control unit 61 performs control to include the position information of the neighboring vehicles in the connected terminal information and to provide the connected terminal information to the base station 30a as the other base station.

[0052] Fig. Fig. 10 is a diagram illustrating an example of a process in which the in-vehicle terminal 11a installed in the vehicle 10 selects a relay station in a wireless communication system 1a according to the second embodiment. Fig. 10, it is assumed that the vehicle 10 can communicate with neighboring vehicles 20 to 26 via V2X and the neighboring vehicles 21 to 25 are connected to the base station 31a. The communication area calculation unit 50 of the in-vehicle terminal 11a installed on the vehicle 10 calculates an approximate communication area 80 of the base station 31a based on the position information of the neighboring vehicles 21 to 25 connected to the base station 31a, acquired via the base station 30a. The communication area 80 of the base station 31a calculated by the communication area calculation unit 50 is an area within the Fig. 10 shown dashed line.

[0053] For example, if the relay station candidate selection unit 47 of the in-vehicle terminal 11a installed on the vehicle 10 selects the neighboring vehicle 25 as the relay station, there is a possibility that the neighboring vehicle 25 will immediately leave the communication area 80 and the neighboring vehicle 25 will perform a handover from the base station 31a to another base station (not shown). After the handover from the base station 31a to another base station, the neighboring vehicle 25 cannot forward the indirect session between the vehicle 10 and the base station 31a. Therefore, the relay station candidate selection unit 47 selects a neighboring vehicle that is expected to be within the communication area 80 of the base station 31a, for example, the neighboring vehicle 22, as the relay station until the vehicle 10 enters the communication area 80 and has a good V2X communication status.

[0054] By selecting the relay station as described above, the relay station candidate selection unit 47 can avoid a situation in which a neighboring vehicle serving as a relay station leaves the communication area 80 of the base station 31a in a short time and therefore it is necessary to search for a neighboring vehicle serving as a relay station again.

[0055] Furthermore, since the relay station candidate selection unit 47 knows the position information of the neighboring vehicles 21 to 25 connected to the base station 31a, it is possible to determine the traveling directions of the neighboring vehicles 21 to 25, the traveling speeds of the neighboring vehicles 21 to 25, whether the neighboring vehicles 21 to 25 are traveling on the same road as the vehicle 10, and the like from a transition in the position information of the neighboring vehicles 21 to 25. Therefore, the relay station candidate selection unit 47 can select the relay station by considering the acquired information about the traveling directions of the neighboring vehicles 21 to 25, the traveling speeds of the neighboring vehicles 21 to 25, whether the neighboring vehicles 21 to 25 are traveling on the same road as the vehicle 10, and the like.For example, the relay station candidate selection unit 47 may determine a relayable time that is a time until a neighboring vehicle leaves the communication area 80 of the base station 31a, and may select the relay station by further using the relayable time.

[0056] Note that the communication range 80 of the base station 31a calculated by the communication range calculation unit 50 can be used not only for the selection of the relay station by the relay station candidate selection unit 47, but also for determining whether the vehicle 10 has entered the communication range 80 of the base station 31a. Generally, the vehicle 10 measures the position of the vehicle 10 using a global positioning system (GPS) (not shown) or the like. Therefore, when the vehicle 10 enters the communication range 80 of the base station 31a, the redundant system management unit 45 of the in-vehicle terminal 11a can control the V2N communication control unit 44 to attempt a direct session with the base station 31a.

[0057] Next, a hardware configuration of the in-vehicle terminal 11a will be described. In the in-vehicle terminal 11a, the relay management unit 46a is implemented by a processing circuit. The processing circuit may be a processor executing a program stored in a RAM or may be dedicated hardware. The same applies to a hardware configuration of the base station. In the base station, the terminal position information acquisition unit 63 is implemented by a processing circuit. The processing circuit may be a processor executing a program stored in a RAM or may be dedicated hardware.

[0058] As described above, according to the present embodiment, when selecting a relay station to be used for establishing the indirect session, the in-vehicle terminal 11a installed on the vehicle 10 acquires the connected terminal information including the position information of the neighboring vehicles connected to the base station to which connection is desired via the base station with which the direct session is established, and selects the relay station using the connected terminal information including the position information. Consequently, in addition to the effects described in the first embodiment, the in-vehicle terminal 11a can avoid a situation in which the connected neighboring vehicle serving as a relay station immediately performs a handover, and thereby stable communication can be performed, that is,it is possible to select a more efficient and suitable relay station to establish a stable indirect session.

[0059] In the second embodiment, the case where the position information of the neighboring vehicles acquired by the terminal position information acquisition unit 63 is included in the connected terminal information acquired by the connected terminal information acquisition unit 62 was described as an example, but this is not limitative. The base station may separately process the position information of the neighboring vehicles acquired by the terminal position information acquisition unit 63 and the connected terminal information acquired by the connected terminal information acquisition unit 62, and provide the pieces of information to another base station as separate information. Third embodiment.

[0060] In each of the first and second embodiments, the in-vehicle terminal selects the relay station. In a third embodiment, a case will be described where some functions for selecting a relay station are implemented by a base station. The third embodiment can be applied to both the first and second embodiments, but the following describes the case where the third embodiment is applied to the second embodiment as an example.

[0061] In the third embodiment, a configuration of the in-vehicle terminal 11a is similar to the configuration of the in-vehicle terminal 11a of the second embodiment, as shown in Fig. 8. In the third embodiment, not shown, a base station that has established a direct session with the vehicle 10 is referred to as base station 30b, and a base station that has not established a direct session with the vehicle 10 and is the target of an indirect session sought by the vehicle 10 is referred to as base station 31b.

[0062] A configuration and operation of base stations 30b and 31b are described. Note that base stations 30b and 31b have similar configurations, and therefore base station 31b is described here as an example. Fig. Fig. 11 is a block diagram showing an exemplary configuration of the base station 31b according to the third embodiment. The base station 31b is constructed by adding a relay station candidate selection unit 64 to the base station 31a of the third embodiment. Fig. 9 shown second embodiment.

[0063] Based on the connected terminal information including the position information of the neighboring vehicles 21 to 25, the relay station candidate selection unit 64 selects a vehicle to be a candidate for a relay station to be used by the vehicle 10 at the time of indirect communication with the base station 31b, where the vehicle 10 is directly connected to the base station 30b as another base station by wireless communication. The relay station candidate selection unit 64 can obtain the connected terminal information including the position information by combining pieces of information acquired by the connected terminal information acquisition unit 62 and the terminal position information acquisition unit 63.The relay station candidate selection unit 64 can recognize the location of the neighboring vehicles 21 to 25 within the communication area 80 based on the connected terminal information including the position information. For a neighboring vehicle located at a position near an edge of the communication area 80, there is a possibility of performing instant handover, and the communication distance from the base station 31b is long, so good communication quality cannot be expected. Therefore, the relay station candidate selection unit 64 selects, for example, a neighboring vehicle located at a position near the center of the communication area 80 as the relay station candidate.

[0064] Regarding the relay station candidate to be selected, the relay station candidate selection unit 64 may select not only one candidate but a plurality of relay station candidates. In this case, the relay station candidate selection unit 64 performs prioritization based on the positions of the plurality of relay stations and the like, and maintains information about the relay station candidates in a list format in which a relay station candidate with a higher priority is placed closer to the top.Since the relay station candidate selection unit 64 knows the position information of the neighboring vehicles 21 to 25 connected to the base station 31b, the relay station candidate selection unit 64 can determine the traveling directions, traveling routes, traveling speeds, and the like of the neighboring vehicles 21 to 25 from a transition in the position information of the neighboring vehicles 21 to 25, and can select the candidate relay station based on this determined information. Furthermore, the relay station candidate selection unit 64 can select the candidate relay station using road information such as accidents, traffic jams, and road closures regarding the road on which the neighboring vehicles 21 to 25 are traveling.

[0065] In a case where there is a request from the base station 30b as another base station, the communication control unit 61 performs control to provide the base station 30b as another base station with relay station candidate information, which is information about the candidate for the relay station selected by the relay station candidate selecting unit 64.

[0066] The base station 30b makes a request to the base station 31b for the relay station candidate information and provides the vehicle 10 with the relay station candidate information acquired from the base station 31b.

[0067] In the in-vehicle terminal 11a of the vehicle 10, the V2N communication unit 43 receives the relay station candidate information provided from the base station 30b, and the connected terminal information holding unit 49 holds the relay station candidate information via the V2N communication control unit 44 similarly to the connected terminal information including the position information. The communication area calculation unit 50 acquires the relay station candidate information from the connected terminal information holding unit 49 and outputs the relay station candidate information to the relay station candidate selection unit 47.The relay station candidate selection unit 47 uses the neighboring vehicle information, the connected terminal information including the position information, the communication area 80, and the relay station candidate information to select the relay station from the relay station candidates indicated by the relay station candidate information. As described above, in the third embodiment, the relay management unit 46a maintains the relay station candidate information, which is information about the neighboring vehicles to be relay station candidates acquired from the base station 30b, and selects the relay station by further using the relay station candidate information.Note that, with respect to a method for acquiring the relay station candidate information, the redundant system management unit 45 of the in-vehicle terminal 11a of the vehicle 10 may make a request to the base station 30b, or similarly to the case of the connected terminal information, in a case where the base station 30b is to make a request to the base station 31b for the relay station candidate information when notified of the failure of the connection with the base station 31b from the vehicle 10, the redundant system management unit 45 of the in-vehicle terminal 11a of the vehicle 10 only needs to notify the base station 30b of the failure of the connection with the base station 31b.

[0068] Fig. 12 is a sequence diagram illustrating a process in which the vehicle 10 having the in-vehicle terminal 11a according to the third embodiment installed thereon acquires connected terminal information and relay station candidate information of the base station 31 via the base station 30. When the direct session with the base station 31b is disrupted (step S200), the vehicle 10 notifies the base station 30b of the disruption of the connection with the base station 31b (step S201). Assuming that the base station 30 should request the connected terminal information and relay station candidate information from the base station 31b when notified from the vehicle 10 of the disruption of the connection with the base station 31b as described above, the vehicle 10 only notifies the base station 30b of the disruption of the connection with the base station 31b.When vehicle 10 reports the connection failure to base station 31b, base station 30b requests the connected terminal information, i.e., information about the neighboring vehicles connected to base station 31b, from base station 31b (step S202a), and requests relay station candidate information, i.e., information about relay station candidates selected by base station 31b, from base station 31b (step S202b). Base station 31b provides the connected terminal information, i.e., information about the neighboring vehicles connected to base station 31b, to base station 30b (step S203a), and provides the relay station candidate information, i.e., information about relay station candidates, to base station 30b (step S203b).When the connected terminal information, which is information about the neighboring vehicles connected to the base station 31b, and the relay station candidate information, which is information about the candidates for the relay station, are provided from the base station 31b, the base station 31b provides the connected terminal information, which is information about the neighboring vehicles connected to the base station 31b, to the vehicle 10 (step S204a), and provides the relay station candidate information, which is information about the candidates for the relay station, to the vehicle 10 (step S204b).Upon acquiring the connected terminal information, which is information about the neighboring vehicles connected to the base station 31b, and the relay station candidate information, which is information about the candidates for the relay station, from the base station 31b, the vehicle 10 selects a candidate for the relay station to be used for an indirect session with the base station 31b based on the neighboring vehicle information, the connected terminal information, and the relay station candidate information (step S205), and requests the selected relay station to relay to the base station 31b in the indirect session (step S206).

[0069] When notifying the base station 30b of the connection failure with the base station 31b in step S201, the in-vehicle terminal 11a of the vehicle 10 may report information such as position information, a traveling direction, a traveling speed, route information, and road information of the vehicle 10 to the base station 30b. In this case, the base station 30b also reports information such as the position information, the traveling direction, the traveling speed, the route information, and the road information of the vehicle 10 to the base station 31b in step S202a or step S202b. Consequently, the base station 31b may select a candidate relay station by considering the position information, the traveling direction, the traveling speed, the route information, the road information, and the like of the vehicle 10.For example, the relay station candidate selection unit 64 of the base station 31b limits neighboring vehicles to neighboring vehicles located within a distance range where V2X communication with the vehicle 10 can be performed, and lists, among the neighboring vehicles, neighboring vehicles that are less likely to perform the handover immediately, neighboring vehicles with a relative speed close to that of the vehicle 10, neighboring vehicles that are expected to travel on the same road for a while, and the like as candidates for the relay station with a higher priority.

[0070] Next, a hardware configuration of the base station is described. In the base station, the relay station candidate selection unit 64 is implemented by a processing circuit. The processing circuit may be a processor executing a program stored in a memory or may be dedicated hardware.

[0071] As described above, according to the present embodiment, when selecting a relay station to be used for establishing the indirect session, the in-vehicle terminal 11a installed on the vehicle 10 acquires the connected terminal information including the position information of the neighboring vehicles connected to the base station to which connection is desired via the base station with which the direct session is established, and the relay station candidate information, and selects the relay station using the connected terminal information including the position information and the relay station candidate information. Therefore, in addition to the effects described in the first embodiment or the second embodiment, the in-vehicle terminal 11a can reduce a processing load in selecting the relay station. Fourth embodiment.

[0072] In the first to third embodiments, the in-vehicle terminal 11 or the in-vehicle terminal 11a of the vehicle 10 acquires the information about the neighboring vehicles connected to the base station as the destination of the indirect session through the base station connected in the direct session. In a fourth embodiment, a case will be described where the in-vehicle terminal 11 or the in-vehicle terminal 11a of the vehicle 10 selects a relay station without receiving information provided from the base station. The fourth embodiment applies to both the in-vehicle terminal 11 and the in-vehicle terminal 11a, and the in-vehicle terminal 11 of the first embodiment will be described below as an example.

[0073] When the direct session with the base station 31 in the vehicle 10 is disrupted, the redundant system management unit 45 of the in-vehicle terminal 11 notifies the relay station candidate selection unit 47 of the disruption. The relay station candidate selection unit 47 knows the neighboring vehicles 20 to 22 that are in V2X communication with the vehicle 10 based on the neighboring vehicle information managed by the neighboring vehicle information management unit 42. The relay station candidate selection unit 47 requests information about the base stations to which the neighboring vehicles 20 to 22 are connected via the relay control unit 48, the V2X communication control unit 41, and the V2X communication unit 40 from the neighboring vehicles 20 to 22 connected via V2X communication.

[0074] The neighboring vehicles 20 to 22 transmit information about the base stations to which the neighboring vehicles 20 to 22 are connected in the V2X communication. Note that the neighboring vehicles 20 to 22 may transmit the information about the base stations to which the neighboring vehicles 20 to 22 are connected as independent information such as a base station list, or may transmit the information together with the position information of the neighboring vehicles 20 to 22 and the like at the time of V2X communication if the neighboring vehicle information management unit 42 of the vehicle 10 manages the information about the neighboring vehicles 20 to 22 as the neighboring vehicle information.

[0075] Fig. 13 is a diagram showing an example of neighboring vehicle information managed by the neighboring vehicle information management unit 42 of the in-vehicle terminal 11 according to the fourth embodiment. Fig. The adjacent vehicle information shown in Fig. 13 illustrates an example of a case in which the adjacent vehicle information management unit 42 of the in-vehicle terminal 11 of the vehicle 10 manages information about the base stations connected to the adjacent vehicles 20 to 22 as adjacent vehicle information. Fig. 13 is obtained by adding information about connected base stations to the neighboring vehicle information of the Fig. 3. The number of connected base stations, which are base stations connected to each neighboring vehicle, is not limited to one, but may be two or more. Note that the neighboring vehicle information management unit 42 may manage information about the base stations connected to the neighboring vehicles 20 to 22 in the form of a base station list transmitted from the neighboring vehicles 20 to 22.

[0076] The relay station candidate selection unit 47 selects as a relay station a neighboring vehicle connected to a base station other than the base station 30 to which the vehicle 10 is connected, for example, the base station 31, on the basis of the Fig. 13 or the base station list managed by the neighboring vehicle information managing unit 42.

[0077] In a case where the fourth embodiment is applied to the second embodiment or the third embodiment, the communication area calculation unit 50 in the in-vehicle terminal 11a installed on the vehicle 10 may calculate an approximate communication area of ​​each base station included in the Fig. 13 shown neighboring vehicle information or contained in the base station list, from the position information of each neighboring vehicle based on the information shown in Fig.13 or the base station list managed by the adjacent vehicle information management unit 42. In this case, the relay station candidate selection unit 47 may select a base station considered to be an optimal relay station from the position information of the vehicle 10 and the like by further using the communication areas calculated by the communication area calculation unit 50 to select a relay station.

[0078] As described above, in the present embodiment, the adjacent vehicle information management unit 42 of the in-vehicle terminal 11 or the in-vehicle terminal 11a manages the adjacent vehicle information including the position information of the adjacent vehicles 20 to 22, the information about the communication status of the V2X communication, and the information about the base stations to which the adjacent vehicles 20 to 22 are connected, each acquired through the V2X communication, and the relay management unit 46 or the relay management unit 46a selects a relay station, which is a neighboring vehicle that relays the indirect session to the base station that cannot be connected via the direct session, based on the adjacent vehicle information.Consequently, the in-vehicle terminal 11 or the in-vehicle terminal 11a no longer needs to collect information about the base station, so that even in a case where a direct session with the base station cannot be established, it is possible to obtain information about relay stations that are candidates in the selection of the relay station.

[0079] For example, the in-vehicle terminal 11 may perform the operation of the first embodiment when at least one direct session has been established, and may perform the operation of the fourth embodiment when no direct session could be established. Similarly, the in-vehicle terminal 11a may perform the operation of the second embodiment or the third embodiment when at least one direct session has been established, and may perform the operation of the fourth embodiment when no direct session could be established.

[0080] The configurations described in the above are merely examples and can be combined with other known technologies, the embodiments can be combined with each other, and part of the configurations can be omitted or modified without departing from the core idea. List of reference symbols

[0081] 1, 1a wireless communication system; 10 vehicle; 11, 11a in-vehicle terminal; 20 to 26 adjacent vehicle; 30, 31, 30a, 31a, 30b, 31b base station; 40 V2X communication unit; 41 V2X communication control unit; 42 adjacent vehicle information management unit; 43 V2N communication unit; 44 V2N communication control unit; 45 redundant system management unit; 46, 46a relay management unit; 47, 64 relay station candidate selection unit; 48 relay control unit; 49 connected terminal information holding unit; 50 communication area calculation unit; 60 communication unit; 61 communication control unit; 62 Connected terminal information acquisition unit; 63 Terminal position information acquisition unit; 70 to 72 Roadside device; 80 Communication section; 90, 93 Processing circuit; 91 Processor; 92 Memory. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 2009-212753

[0004]

Claims

[1] In-vehicle terminal installed on a vehicle and wirelessly communicates with a variety of base stations via a variety of paths, the in-vehicle terminal comprising: a vehicle-to-vehicle communication control unit for controlling communication with a neighboring vehicle that is close to the vehicle and capable of vehicle-to-vehicle communication; a neighboring vehicle information management unit for managing neighboring vehicle information, including position information of the neighboring vehicle and information about the communication status of the vehicle-to-vehicle communication obtained through the vehicle-to-vehicle communication; a base station communication control unit for performing a control to provide a first base station, which is the base station connected via direct communication, with information about a second base station, which is the base station that cannot be connected via direct communication, and to request the first base station to provide connected terminal information, which is information about the adjacent vehicle connected to the second base station; a relay management unit for storing the connected terminal information obtained from the first base station and for selecting a relay station, which is the adjacent vehicle, that forwards indirect communication to the second base station based on the adjacent vehicle information and the connected terminal information; and a redundant system management unit for managing a connection with the first base station and the second base station and for instructing the relay management unit to perform indirect communication with the second base station if the second base station cannot be connected via direct communication. [2] In-vehicle terminal according to claim 1, wherein the adjacent vehicle has a roadside device installed on one side of a road on which the vehicle is traveling. [3] In-vehicle terminal according to claim 1 or 2, wherein The connected terminal information includes position information of the adjacent vehicle that is connected to the second base station, and The relay management unit calculates a communication range of the second base station based on the connected terminal information and selects the relay station using the communication range of the second base station. [4] In-vehicle terminal according to claim 3, wherein the relay management unit determines a forwardable time, which is a time until the adjacent vehicle leaves the communication range of the second base station, and selects the relay station using the forwardable time. [5] In-vehicle terminal according to claim 3 or 4, wherein when the vehicle reaches the communication range of the second base station, the redundant system management unit controls the base station communication control unit to attempt direct communication with the second base station. [6] In-vehicle terminal according to any one of claims 1 to 5, wherein the relay management unit maintains relay station candidate information, which is information about the adjacent vehicle that is to be a candidate for the relay station procured by the first base station, and selects the relay station using the relay station candidate information. [7] In-vehicle terminal according to any one of claims 1 to 6, wherein the neighboring vehicle information management unit manages the neighboring vehicle information, including position information of the neighboring vehicle, information about the communication status of the vehicle-to-vehicle communication, and information about the second base station to which the neighboring vehicle is connected, which is obtained through the vehicle-to-vehicle communication, and The relay management unit selects the relay station based on the neighboring vehicle information, which forwards the indirect connection to the second base station that cannot be connected via a direct connection. [8] Base station in a wireless communication system in which a vehicle having an in-vehicle terminal installed on it performs wireless communication with a plurality of base stations through a plurality of paths, the base station comprising: a connected terminal information acquisition unit for acquiring identification information of the vehicle with which wireless communication is carried out and for storing the identification information as connected terminal information; and a communication control unit for controlling wireless communication with the vehicle and communication with another base station and for performing a control to provide the connected terminal information to the other base station when a request is received from the other base station. [9] Base station according to claim 8, further comprising: a terminal position information procurement unit for obtaining and maintaining position information of the vehicle with which wireless communication is carried out, wherein In a case where a request is received from the other base station, the communication control unit performs a control to include the vehicle's position information in the connected terminal information and provide the connected terminal information to the other base station. [10] Base station according to claim 9, further comprising: a relay station candidate selection unit for selection, based on the connected terminal information, comprising position information of a first vehicle, which is the vehicle, of the first vehicle as a candidate for a relay station to be used by a second vehicle at a time of indirect communication with the base station, wherein the second vehicle is directly connected to the other base station by wireless communication, wherein In a case where a request is received from the other base station, the communication control unit performs a control operation to provide the other base station with information about the candidate for the relay station. [11] Wireless communication system, comprising: the vehicle-internal terminal according to claim 1 or 2; and the base station according to claim 8. [12] Control circuit for controlling an in-vehicle terminal installed on a vehicle and performing wireless communication with a variety of base stations via a variety of paths, wherein the control circuit causes the in-vehicle terminal to perform: Control of communication with a neighboring vehicle that is located near the vehicle and is capable of vehicle-to-vehicle communication; Managing neighboring vehicle information, including position information of the neighboring vehicle and information about the communication status of the vehicle-to-vehicle communication obtained through vehicle-to-vehicle communication; Control to provide a first base station, which is the base station connected via direct communication, with information about a second base station, which is the base station that cannot be connected via direct communication, and to request the first base station to provide connected terminal information, which is information about the adjacent vehicle connected to the second base station; Maintaining the connected terminal information obtained from the first base station and selecting a relay station, which is the adjacent vehicle, that forwards indirect communication to the second base station based on the adjacent vehicle information and the connected terminal information; and Managing a connection between the first base station and the second base station, and instructing indirect communication with the second base station when the second base station cannot be connected via direct communication. [13] Storage medium on which a program is stored for controlling an in-vehicle terminal which is installed on a vehicle and which performs wireless communication with a large number of base stations via a variety of paths, wherein the program causes the vehicle's internal terminal to perform: Control of communication with a neighboring vehicle that is located near the vehicle and is capable of vehicle-to-vehicle communication; Managing neighboring vehicle information, including position information of the neighboring vehicle and information about the communication status of the vehicle-to-vehicle communication obtained through vehicle-to-vehicle communication; Control to provide a first base station, which is the base station connected via direct communication, with information about a second base station, which is the base station that cannot be connected via direct communication, and to request the first base station to provide connected terminal information, which is information about the adjacent vehicle connected to the second base station; Maintaining the connected terminal information obtained from the first base station and selecting a relay station, which is the adjacent vehicle, that forwards indirect communication to the second base station based on the adjacent vehicle information and the connected terminal information; and Managing a connection between the first base station and the second base station, and instructing indirect communication with the second base station when the second base station cannot be connected via direct communication. [14] Relay station selection procedure performed by an in-vehicle terminal installed on a vehicle and performing wireless communication with a multitude of base stations via a multitude of paths, the relay station selection procedure comprising: a first step, which is carried out by a vehicle-to-vehicle communication control unit, to control communication with a neighboring vehicle that is close to the vehicle and capable of vehicle-to-vehicle communication; a second step, which is carried out by a neighboring vehicle information management unit, to manage neighboring vehicle information, including position information of the neighboring vehicle and information about the communication status of the vehicle-to-vehicle communication obtained through the vehicle-to-vehicle communication; a third step, which is carried out by a base station communication control unit, to perform a control to provide a first base station, which is the base station connected via direct communication, with information about a second base station, which is the base station that cannot be connected via direct communication, and to request the first base station to provide connected terminal information, which is information about the adjacent vehicle connected to the second base station; a fourth step, performed by a relay management unit, to store the connected terminal information obtained from the first base station and to select a relay station, which is the adjacent vehicle, that forwards indirect communication to the second base station based on the adjacent vehicle information and the connected terminal information; and a fifth step, which is carried out by a redundant system management unit, to manage a connection with the first base station and the second base station and to instruct the relay management unit to perform indirect communication with the second base station if the second base station cannot be connected via direct communication.

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