Relay base station

Abstract

To provide a relay base station capable of improving the possibility that communication terminals around a mobile object can access a base station without interfering with the running of the mobile object.SOLUTION: A relay base station 3 mounted on a mobile object 10 includes an acquisition processing unit 41 that acquires a status signal representing the status of the mobile object 10, and a communication control unit 42 that executes a second communication mode in which wireless communication between a base station 11 and at least one communication terminal 12 is relayed when the status signal represents that a battery 1 of the mobile object 10 is being charged, and on the other hand executes a first communication mode in which communication for running control performed by the mobile object 10 via the base station 11 is performed when the status signal represents something other than that the battery 1 of the mobile object 10 is being charged.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a relay base station mounted on a vehicle.

Background Art

[0002] There has been proposed a technique of mounting a wireless communication device on a vehicle to enable communication with devices outside the vehicle or devices inside the vehicle (see Patent Document 1).

[0003] The in-vehicle communication device disclosed in Patent Document 1 has a control unit capable of implementing a first wireless communication mode for performing wireless communication with an in-vehicle device mounted on the vehicle and a second wireless communication mode for performing wireless communication outside the vehicle via an access point. Then, the control unit implements the first wireless communication mode along with the drivable state of the vehicle, and stops the first wireless communication mode and implements the second wireless communication mode along with the transition of the vehicle from the drivable state to the non-drivable state.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] It is expected to more effectively utilize the wireless communication device mounted on the vehicle.

[0006] Therefore, an object of the present invention is to provide a relay base station capable of improving the possibility that a communication terminal around a moving body can access the base station without hindering the running of the moving body.

Means for Solving the Problems

[0007] According to one embodiment, there is provided a relay base station capable of switching and executing only one of a first communication mode for performing communication for travel control performed by a mobile body via a base station and a second communication mode for relaying wireless communication between the base station and at least one communication terminal. This relay base station includes an acquisition processing unit that acquires a state signal representing the state of the mobile body, and a communication control unit that executes the second communication mode when the state signal indicates that the battery of the mobile body is being charged, and executes the first communication mode when the state signal indicates otherwise than the battery of the mobile body being charged.

[0008] In this relay base station, it is preferable that the mobile body is a mobile body that executes a predetermined operation by autonomous driving.

[0009] In this relay base station, during the execution of the second communication mode, the communication control unit sets the application range of the second communication mode according to the number of other mobile bodies equipped with other relay base stations that can communicate directly.

Advantages of the Invention

[0010] The relay base station according to the present disclosure has an effect that it can improve the possibility that communication terminals around the mobile body can access the base station without hindering the travel of the mobile body.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Best Mode for Carrying Out the Invention

[0012] Hereinafter, with reference to the drawings, a relay base station, a communication relay method executed by the relay base station, and a computer program for communication relay will be described. This relay base station is mounted on a mobile body. Further, this relay base station can switch between a relay communication mode for relaying wireless communication between a base station and at least one communication terminal and a traveling communication mode for executing communication for the traveling of the mobile body via the base station and execute them. And when the state signal indicating the state of the mobile body indicates that the battery of the mobile body is being charged, this relay base station executes the relay communication mode, while when the state signal indicates that the mobile body is traveling, it executes the traveling communication mode.

[0013] The mobile body on which the relay base station is mounted can be, for example, various vehicles or a robot that can autonomously travel and automatically moves to a charging spot when the remaining capacity of the mounted battery becomes equal to or less than a predetermined value and executes a predetermined operation. The predetermined operation can be, for example, an operation related to work such as cleaning or delivery. Hereinafter, an example in which the relay base station is mounted on a vehicle capable of charging the battery from the outside will be described.

[0014] FIG. 1 is a schematic configuration diagram of a vehicle equipped with a relay base station. Vehicle 10 includes a battery 1, an electronic control unit (ECU) 2, and a wireless communication device 3 which is an example of a relay base station. The ECU 2 and the wireless communication device 3 are communicably connected via an in-vehicle network compliant with a standard such as a controller area network. Further, the vehicle 10 may be equipped with a distance sensor (not shown), such as a camera (not shown) or a LiDAR sensor, for photographing the surroundings of the vehicle 10 to measure the distance to an object around the vehicle 10. Furthermore, the vehicle 10 may be equipped with a GPS receiver (not shown) for measuring the position of the vehicle 10. Additionally, the vehicle 10 may be equipped with a navigation device (not shown) that searches for a planned route of the vehicle 10 and navigates the vehicle 10 to travel along the planned route.

[0015] The battery 1 is the power source of the vehicle 10 and is composed of, for example, a lithium-ion battery or other rechargeable battery and a control circuit for controlling the charge and discharge of the battery included in the battery 1. The battery 1 supplies power to each device mounted on the vehicle 10, such as the ECU 2 and the wireless communication device 3. Further, when the vehicle 10 is a vehicle having a motor (not shown) as one of the power sources, the power supplied from the battery 1 may be supplied to the motor via a circuit for driving the motor, such as an inverter.

[0016] In this embodiment, it is possible to charge the battery 1 from a charging facility provided outside the vehicle 10 via a charging interface (not shown) provided in the vehicle 10. The control circuit provided in the battery 1 outputs, at predetermined intervals, a signal indicating whether the battery 1 is being charged and the charging status or remaining capacity of the battery 1 (hereinafter referred to as a charging status signal) to the ECU 2.

[0017] The ECU 2 controls the running of the vehicle 10 or supports the driver of the vehicle 10 in driving. For this purpose, the ECU 2 has at least one processor, a memory, and a communication interface for connecting to the in-vehicle network. When a motor is used as one of the power sources of the vehicle 10, the ECU 2 adjusts the power supplied from the battery 1 to the motor according to the accelerator opening. Further, the ECU 2 detects an object existing around the vehicle 10 from an image obtained by a camera (not shown) that photographs the surroundings of the vehicle 10, and may control the steering angle, brakes, and accelerator of the vehicle 10 so that the detected object does not collide with the vehicle 10. Furthermore, the ECU 2 detects a lane marking line that demarcates the own lane in which the vehicle 10 is traveling from the image, and controls the steering angle based on the detected lane marking line so that the vehicle 10 maintains traveling in the own lane. Alternatively, when the vehicle 10 is about to deviate from the own lane, the ECU 2 may warn the driver of the deviation via a display device provided in the vehicle interior or the like.

[0018] Furthermore, the ECU 2 uses the information received from other devices outside the vehicle 10 via the wireless communication device 3 for the control of the vehicle 10. For example, the ECU 2 refers to a high-precision map received from a map server (not shown) via the wireless communication device 3, identifies the road on which the vehicle 10 is traveling, and may control each part of the vehicle 10 so that the vehicle 10 travels at the speed limit set for the identified road. Further, the ECU 2 may identify the own lane in which the vehicle 10 is traveling by collating features such as lane marking lines detected from the image with the corresponding features represented in the high-precision map. And when the identified own lane is different from the lane leading to the destination indicated by the planned route set by a navigation device (not shown), the ECU 2 may control each part of the vehicle 10 to move to the lane leading to the destination. The high-precision map includes various types of information used in the automatic driving control of the vehicle 10. For example, the high-precision map represents road markings such as lane marking lines, road signs, and the speed limits of individual road sections for each individual road section within the area represented in the high-precision map.

[0019] Furthermore, the ECU 2 may utilize the traffic information received from a traffic information server (not shown) via the wireless communication device 3 for the driving control of the vehicle 10. For example, if the traffic information indicates that there is a section on the planned driving route where traffic control is being carried out, the ECU 2 may request the navigation device to search for a detour route. Then, the ECU 2 may drive the vehicle 10 along the detour route received from the navigation device.

[0020] Furthermore, the ECU 2 manages the remaining capacity of the battery 1 based on the charge status signal received from the battery 1. For example, when the remaining capacity of the battery 1 becomes less than a predetermined amount, the ECU 2 warns the driver that the remaining capacity of the battery 1 is low via a display device provided in the vehicle interior or the like. Furthermore, the ECU 2 generates a status signal indicating the state of the vehicle 10 at each predetermined cycle or each time the state of the vehicle 10 changes, and outputs the generated status signal to the wireless communication device 3 via the in-vehicle network. When the charge status signal received from the battery 1 indicates that the battery 1 is being charged, the ECU 2 includes a value representing that the battery 1 is being charged in the status signal. Also, when the vehicle 10 is in motion, the ECU 2 includes a value representing that the vehicle 10 is in motion in the status signal. Note that the ECU 2 determines that the vehicle 10 is in motion when the ignition switch of the vehicle 10 is turned on. Alternatively, the ECU 2 may determine that the vehicle 10 is in motion when the shift position of the vehicle 10 is in a position other than parking.

[0021] Furthermore, the ECU 2 outputs a signal to be transmitted to a device outside the vehicle 10, such as a request for distribution of a high-precision map, to the wireless communication device 3 via the in-vehicle network.

[0022] The wireless communication device 3 is an example of a relay base station, and is capable of relaying (relaying) wireless communication between the base station 11 installed outside the vehicle 10 and one or more communication terminals 12 located around the vehicle 10 or inside the vehicle 10. In the present embodiment, when the status signal received from the ECU 2 indicates that the battery is being charged, the wireless communication device 3 relays the wireless communication between the base station 11 and the communication terminal 12 (relay communication mode). On the other hand, when the status signal received from the ECU 2 indicates that the vehicle 10 is running, the wireless communication device 3 executes communication for the running of the vehicle 10 via the base station 11 (running communication mode). Hereinafter, for convenience of explanation, the signal communicated between the base station 11 and the communication terminal 12 relayed by the wireless communication device 3 may be referred to as a relay signal.

[0023] FIG. 2 is a hardware configuration diagram of the wireless communication device 3. The wireless communication device 3 includes an antenna 31, a wireless processing circuit 32, a wired interface 33, a memory 34, and a processor 35. The wireless processing circuit 32, the wired interface 33, the memory 34, and the processor 35 may each be implemented in the wireless communication device 3 as separate circuits, or may be implemented in the wireless communication device 3 as one integrated circuit.

[0024] The antenna 31 transmits the uplink signal or the downlink relay signal transmitted from the wireless processing circuit 32 as a wireless signal. The antenna 31 also receives the wireless signal from the base station 11, converts it into an electrical signal to obtain a downlink signal, and transmits the downlink signal to the wireless processing circuit 32. Further, the antenna 31 receives the wireless signal from the communication terminal 12, converts it into an electrical signal to obtain an uplink relay signal, and transmits the relay signal to the wireless processing circuit 32. Note that the antenna 31 may have separately an antenna for communication with the base station 11 and an antenna for communication with the communication terminal 12.

[0025] The wireless processing circuit 32 analogizes the uplink signal or the downlink relay signal received from the processor 35, and then superimposes it on a carrier wave having a radio frequency specified by the processor 35. Then, the wireless processing circuit 32 amplifies the uplink signal or the relay signal superimposed on the carrier wave to a desired level by a high-power amplifier (not shown), and transmits the amplified uplink signal or relay signal to the antenna 31.

[0026] Also, the wireless processing circuit 32 amplifies the downlink signal or the uplink relay signal received from the antenna 31 by a low-noise amplifier (not shown). The wireless processing circuit 32 multiplies the amplified downlink signal or relay signal by a periodic signal having an intermediate frequency to convert the frequency of the downlink signal or relay signal from the radio frequency to the baseband frequency. Then, the wireless processing circuit 32 analog / digitally converts the downlink signal or relay signal having the baseband frequency and then passes it to the processor 35.

[0027] The wired interface 33 is an example of an in-vehicle communication unit and has an interface circuit for connecting the wireless communication device 3 to the in-vehicle network. That is, the wired interface 33 is connected to the ECU 2 via the in-vehicle network. The wired interface 33 passes the status signal received from the ECU 2 to the processor 35. Also, the wired interface 33 outputs the information (such as a high-precision map or traffic information) received from the processor 35 and used for the running of the vehicle 10 to the ECU 2 via the in-vehicle network.

[0028] Memory 34 is an example of a storage unit and has, for example, a non-rewritable non-volatile semiconductor memory and a rewritable non-volatile semiconductor memory or a volatile semiconductor memory. Then, memory 34 stores various information for communicating with base station 11 and communication terminal 12, and various programs operating in wireless communication device 3. Further, memory 34 may temporarily store signals received from base station 11, communication terminal 12 or ECU2, and signals transmitted to any of base station 11, communication terminal 12 or ECU2.

[0029] Processor 35 has one or more CPUs (Central Processing Units) and its peripheral circuits. Processor 35 may further have other arithmetic circuits such as a logical arithmetic unit or a numerical arithmetic unit. Then, processor 35 executes processes related to wireless communication between base station 11 and wireless communication device 3, and relay communication between base station 11 and communication terminal 12.

[0030] FIG. 3 is a functional block diagram of processor 35. Processor 35 has an acquisition processing unit 41 and a communication control unit 42. Each of these units included in processor 35 is, for example, a functional module realized by a computer program operating on processor 35. Alternatively, each of these units included in processor 35 may be a dedicated arithmetic circuit incorporated in processor 35.

[0031] Acquisition processing unit 41 acquires a signal, particularly a status signal, from ECU2 via wired interface 33. Then, acquisition processing unit 41 passes the received signal to communication control unit 42.

[0032] Communication control unit 42 executes processes related to a communication mode according to the latest status signal received from ECU2 among the relay communication mode and the traveling communication mode. In the present embodiment, when the status signal indicates that battery 1 is being charged, the relay communication mode is executed. On the other hand, when the status signal indicates that vehicle 10 is traveling, the traveling communication mode is executed.

[0033] When executing the relay communication mode, the communication control unit 42 performs various processes for performing wireless communication between the base station 11 and the communication terminal 12 and the wireless communication device 3 in accordance with a predetermined wireless communication standard. The predetermined wireless communication standard can be, for example, a wireless communication standard for the so-called fifth-generation mobile communication system formulated by the 3rd Generation Partnership Project (3GPP, registered trademark), or a standard for other mobile communication systems. In addition, the processes for performing wireless communication include, for example, processes such as establishment of communication between the base station 11 and the communication terminal 12 and the wireless communication device 3, allocation of wireless resources, and transmission power control. Further, the communication control unit 42 outputs the relay signal to the wireless processing circuit 32 so that the downlink relay signal received from the wireless processing circuit 32 is transmitted to the communication terminal 12 using the wireless resources allocated to the wireless communication with the communication terminal 12. Similarly, the communication control unit 42 outputs the relay signal to the wireless processing circuit 32 so that the uplink relay signal received from the wireless processing circuit 32 is transmitted to the base station 11 using the wireless resources allocated to the wireless communication with the base station 11.

[0034] In addition, when executing the driving communication mode, the communication control unit 42 performs various processes for executing wireless communication between the base station 11 and the wireless communication device 3 in accordance with a predetermined wireless communication standard. Further, the communication control unit 42 generates an uplink signal including a signal received from the ECU 2 and to be transmitted to other devices outside the vehicle 10 (for example, a distribution request for a high-precision map). Then, the communication control unit 42 performs encoding processing such as error correction coding on the uplink signal. Further, the communication control unit 42 modulates the uplink signal according to a predetermined modulation method. And the communication control unit 42 outputs the modulated uplink signal to the wireless processing circuit 32. Further, the communication control unit 42 demodulates the downlink signal received from the wireless processing circuit 32 and performs error correction decoding. Then, the communication control unit 42 extracts information used for the driving of the vehicle 10, such as a high-precision map or traffic information, from the decoded downlink signal. The communication control unit 42 outputs the information used for the driving of the vehicle 10 extracted from the downlink signal to the ECU 2 via the wired interface 33.

[0035] During the execution of the relay communication mode, it is preferable that the wireless communication device 3 stops the communication for the driving of the vehicle 10, but it may also execute the communication for the driving of the vehicle 10. When the wireless communication device 3 executes the communication for the driving of the vehicle 10 during the execution of the relay communication mode, it is preferable that the communication control unit 42 executes the relay communication between the base station 11 and the communication terminal 12 with priority over the communication for the driving of the vehicle 10.

[0036] Also, during the execution of the driving communication mode, it is preferable that the wireless communication device 3 stops the relay communication between the base station 11 and the communication terminal 12. Thereby, the wireless communication device 3 can suppress the communication delay when receiving information used for the driving of the vehicle 10 from other devices via the base station 11, so that it can prevent the driving of the vehicle 10 from being hindered.

[0037] Figures 4(a) and 4(b) are diagrams for explaining the outline of communication relay processing. In the example shown in Fig. 4(a), the vehicle 10 is parked at the charging station 400, and the battery 1 of the vehicle 10 is being charged using the charging equipment of the charging station 400. Therefore, the wireless communication device 3 executes the relay communication mode and relays the wireless communication between the base station 11 and the communication terminal 12 located around the vehicle 10. As a result, even when the communication terminal 12 cannot directly receive the wireless signal from the base station 11, the communication terminal 12 can perform wireless communication with the base station 11 via the wireless communication device 3.

[0038] In the example shown in Fig. 4(b), since the vehicle 10 is in motion, the wireless communication device 3 executes the traveling communication mode. Then, the wireless communication device 3 transmits and receives various information used for the traveling of the vehicle 10 to and from other devices (not shown) provided outside the vehicle 10 via the base station 11. And the wireless communication device 3 outputs the received information to the ECU 2.

[0039] Figure 5 is an operation flowchart of communication relay processing. The processor 35 executes communication relay processing according to this operation flowchart at a predetermined cycle.

[0040] The acquisition processing unit 41 of the processor 35 acquires a status signal from the ECU 2 via the in-vehicle network and the wired interface 33 (step S101). When the status signal is acquired, the communication control unit 42 of the processor 35 determines whether the status signal indicates that the battery 1 is being charged (step S102). If the status signal indicates that the battery 1 is being charged (step S102 - Yes), the communication control unit 42 executes the relay communication mode (step S103). On the other hand, if the status signal indicates that the vehicle 10 is in motion (step S102 - No), the communication control unit 42 executes the traveling communication mode (step S104). After step S103 or S104, the processor 35 ends the relay communication processing.

[0041] As described above, when the state signal indicating the state of the mobile body indicates that the battery of the mobile body is being charged, this relay base station mounted on the mobile body executes the relay communication mode. On the other hand, when the state signal indicates that the mobile body is in motion, this relay base station executes the traveling communication mode. In this way, this relay base station relays the communication between the communication terminal and the base station by using the timing of battery charging that does not cause a problem even if communication resources are not allocated to the traveling of the mobile body. Therefore, this relay base station can improve the possibility that communication terminals around the mobile body can access the base station without hindering the traveling of the mobile body.

[0042] According to a modification example, the state of the vehicle 10 may be managed by a server (not shown) provided outside the vehicle 10 and connected to the base station 11 via a core network. In this case, in addition to the wireless communication device 3, the vehicle 10 may be equipped with another wireless communication terminal (not shown) connected to the in-vehicle network and a short-range wireless communication circuit (not shown) compliant with a predetermined short-range wireless communication standard. Note that the wireless communication standard complied with by the other wireless communication terminal is different from the wireless communication standard complied with by the wireless communication device 3, and the communication speed may be limited as compared with the wireless communication standard complied with by the wireless communication device 3. Also, the predetermined short-range wireless communication standard can be, for example, Bluetooth (registered trademark) or ZigBee (registered trademark). Also, in this example, the wireless communication device 3 may not be connected to the in-vehicle network. Therefore, it is preferable that the wireless communication device 3 has a short-range wireless communication circuit compliant with a predetermined short-range wireless communication standard instead of the wired interface 33. In this case, the ECU 2 transmits the status signal to the server via the other wireless communication terminal at a predetermined cycle. Then, the wireless communication device 3 may receive the status signal from the server via the base station 11 at a predetermined cycle. Furthermore, the wireless communication device 3 may transfer the information used for the running of the vehicle 10 received in the running communication mode to the ECU 2 via the short-range wireless communication circuit. According to this modification example, even if the wireless communication device 3 is not connected to the in-vehicle network, the wireless communication device 3 can execute the same processing as in the above-described embodiment and obtain the same effects as in the above-described embodiment.

[0043] Also, as described above, the mobile body equipped with the relay base station according to the above-described embodiment or modification example may be a robot that is capable of autonomous driving and automatically moves to a charging spot when the remaining capacity of the mounted battery becomes equal to or less than a predetermined value and executes a predetermined operation. By mounting a relay base station on such a mobile body, it becomes possible to effectively utilize the mobile body even during charging when the mobile body cannot perform a predetermined operation.

[0044] Note that there may be multiple charging spots such as the charging station shown in Fig. 4(a). In such a case, it is preferable that the charging spot used by the moving body equipped with the relay base station for battery charging is selected so that the applicable range of relay communication becomes wider or the number of communication terminals 12 to which relay communication can be applied increases. Therefore, according to another modification, a server (not shown) connected to the base station 11 via the core network selects the charging spot used by each moving body equipped with the relay base station and notifies the selected charging spot to the moving body. In this case, the server stores, for each moving body equipped with the relay base station, a list (hereinafter sometimes referred to as a spot list) indicating the positions and available time zones of a plurality of charging spots available to the moving body. Then, when the server receives a remaining amount signal indicating that the remaining amount of the battery is equal to or less than a predetermined amount from any moving body via the relay base station, it refers to the spot list and selects any of the charging spots whose current time is included in the available time zone. The server transmits an instruction signal instructing the moving body to head to the selected charging spot to the moving body via the base station 11 and the relay base station. The instruction signal includes the position of the selected charging spot. When the moving body receives the instruction signal, it autonomously moves to the charging spot indicated by the received instruction signal. For example, in the above embodiment, when the ECU 2 of the vehicle 10 receives the instruction signal via the base station 11 and the wireless communication device 3, the ECU 2 automatically controls the vehicle 10 so that the vehicle 10 moves to the position of the charging spot indicated by the received instruction signal. Alternatively, the ECU 2 may notify the driver of the position of the charging spot indicated by the received instruction signal via a user interface provided in the passenger compartment of the vehicle 10. Then, by manual driving of the driver, the vehicle 10 may move to the charging spot.

[0045] The server determines the charging spot to be selected based on indicators such as the number of moving bodies existing at each charging spot, whether there are moving bodies likely to complete charging, or the geographical distribution of the communication terminals 12 connected to any one of one or more base stations. At this time, the server calculates, for each charging spot, an evaluation value that becomes higher as the range where relay communication can be applied becomes wider or as the number of communication terminals 12 that can utilize relay communication increases, based on at least one of the above-mentioned indicators. Then the server selects the charging spot with the maximum evaluation value. Specifically, the server increases the evaluation value for charging spots with fewer moving bodies being charged. This is because charging spots with fewer moving bodies being charged have fewer relay base stations capable of executing relay communication, so there is a higher possibility that there are communication terminals that cannot utilize relay communication. Also, the server increases the evaluation value for charging spots where there are moving bodies likely to complete charging. This is because moving bodies that have completed charging are likely to move away from that charging spot, and as a result, the relay communication being executed by the relay base station installed on the moving body that has completed charging may be interrupted. Note that the server can calculate the above-mentioned evaluation value by receiving, from each moving body being charged, a signal representing the predicted time until charging completion or the remaining battery capacity, via the relay base station and the base station. Furthermore, the server may count, for each charging spot, the number of communication terminals 12 located within a predetermined distance from that charging spot, with reference to the geographical distribution of the communication terminals 12 connected to any one of one or more base stations. Note that these one or more base stations are preferably so-called macro base stations. Furthermore, these one or more base stations are not limited to the base station 11 and may include other base stations compliant with wireless communication standards other than the wireless communication standard to which the base station 11 conforms. And the server increases the evaluation value for charging spots where the number of communication terminals 12 located within a predetermined distance is large. In this case, the server receives, from each individual base station, information representing the number of registered communication terminals 12 per cell and the geographical range of that cell at predetermined intervals.Then, for each charging spot, the server may simply calculate the total number of communication terminals 12 registered in the cells overlapping the area within a predetermined distance from the charging spot as the number of communication terminals 12 located within the predetermined distance from the charging spot. When calculating an evaluation value based on a plurality of indicators, the server may simply use the sum of the individual evaluation values calculated for each of the plurality of indicators as the evaluation value again.

[0046] According to this modification, a communication system including a relay base station can expand the range applicable to relay communication or increase the number of communication terminals 12 to which relay communication can be applied.

[0047] According to another modification, during charging of the battery of the moving body on which the relay base station is mounted, the relay base station may set the applicable range of the relay communication mode based on the number of other moving bodies being charged at the charging spot where the moving body is located. For example, the relay base station may limit the directivity of the radio signal output from the antenna of the relay base station or reduce the radio signal power as the number of other moving bodies being charged increases. In that case, the relay base station may count the number of relay base stations capable of directly communicating with each other as the number of other moving bodies being charged.

[0048] A computer program for causing a computer to realize the functions of each part of the processor of the relay base station according to the above embodiment or modification may be provided in a form stored in a computer-readable recording medium. Note that the computer-readable recording medium can be, for example, a magnetic recording medium, an optical recording medium, or a semiconductor memory.

[0049] As described above, those skilled in the art can make various changes according to the implemented form within the scope of the present invention.

Description of Reference Numerals

[0050] 1 Battery 2 ECU 3 Wireless Communication Device (Relay Base Station) 10 Vehicle 11 Base station 12 Communication terminal 31 Antenna 32 Radio processing circuit 33 Wired interface 34 Memory 35 Processor 41 Acquisition processing unit 42 Communication control unit

Claims

Claim 1 A relay base station that is mounted on a moving body and can execute only one of a first communication mode for performing communication for travel control performed by the moving body via a base station and a second communication mode for relaying wireless communication between the base station and at least one communication terminal, an acquisition processing unit that acquires a state signal representing the state of the moving body; a communication control unit that executes the second communication mode when the state signal indicates that the battery of the moving body is being charged, and executes the first communication mode when the state signal indicates otherwise than that the battery of the moving body is being charged; A relay base station having the above. Claim 2 The relay base station according to claim 1, wherein the moving body is a moving body that executes a predetermined operation by autonomous driving. Claim 3 The relay base station according to claim 1 or 2, wherein the communication control unit sets an application range of the second communication mode according to the number of other moving bodies equipped with other relay base stations that can communicate directly during execution of the second communication mode.

Images