Communication system, communication device for vehicle, relay device, and communication device for control

Abstract

This communication system (100) for communication between a first communication device (1) and a second communication device (2) comprises the first communication device, the second communication device, a first relay device (4), and a second relay device (5). The first communication device is configured to communicate with the second communication device by using, in combination, a first communication path for communicating with the second communication device via the first relay device without passing through the second relay device, and a second communication path for communicating with the second communication device via the second relay device without passing through the first relay device.

Description

Communication system, vehicle communication device, relay device, and control communication device CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This international application claims the benefit of Japanese Patent Application No. 2024-065541, filed with the Japan Patent Office on April 15, 2024, the entire disclosure of which is incorporated herein by reference.

[0002] The present disclosure relates to a communication system, a vehicle communication device, a relay device, and a control communication device.

[0003] Patent Document 1 below discloses the configuration of a multi-hop wireless ad hoc network. In the configuration of Patent Document 1, all relay devices in the network are synchronized. While data is being transmitted and received in the network, all relay devices are active, and while data is not being transmitted and received, all relay devices are asleep. According to the configuration of Patent Document 1, when all relay devices are asleep, the power consumption of the relay devices is reduced.

[0004] JP 2011-223419 A

[0005] However, as a result of detailed investigation by the inventors, the following problem was discovered: In the configuration of Patent Document 1, when the amount of data communication is large, for example, and the time it takes to send and receive data is long, not all relay devices go into sleep mode, and the power consumption of the relay devices is not reduced.

[0006] One aspect of the present disclosure provides a technique that can reduce the power consumption of a relay device that constitutes a network.

[0007] One aspect of the present disclosure is a communication system for communication between a first communication device and a second communication device, comprising: a first communication device, a second communication device, a first relay device, and a second relay device. The first communication device is a communication device mounted on a target vehicle, which is a predetermined vehicle, and capable of wireless communication. The first relay device is a communication device mounted on a first vehicle, which is a vehicle different from the target vehicle, and capable of wireless communication. The second relay device is a communication device mounted on a second vehicle, which is a vehicle different from the target vehicle and the first vehicle, and capable of wireless communication. The first communication device is configured to communicate with the second communication device using a first communication path, which is a communication path for communicating with the second communication device via the first relay device without passing through the second relay device, and a second communication path, which is a communication path for communicating with the second communication device via the second relay device without passing through the first relay device.

[0008] With this configuration, since multiple relay devices are connected in parallel, it is possible to prevent the communication load from concentrating on one relay device compared to a communication system in which only one communication path is used and one relay device is always in communication, and therefore it is possible to reduce the power consumption of each relay device compared to a case in which the communication load is concentrated.

[0009] One aspect of the present disclosure may be a vehicle communication device, a relay device, or a control communication device.

[0010] FIG. 1 is a diagram for explaining an overview of a communication system. FIG. 2 is a block diagram for explaining the communication system. FIG. 3A is a diagram for explaining time slots. FIG. 3B is another diagram for explaining time slots. FIG. 4 is a sequence diagram when a relay device inquires about time slots from a third communication device. FIG. 5 is a sequence diagram when data is transmitted from a first communication device to a second communication device. FIG. 6 is a sequence diagram when the first communication device receives data from a second communication device. FIG. 7 is a diagram for explaining an example in which the communication available times of each relay device are different.

[0011] Hereinafter, exemplary embodiments of the present disclosure will be described with reference to the drawings.

[0012] 1. Embodiments 1-1. Overview of Communication System A communication system 100 shown in FIG. 1 is a communication system for communication between a first communication device 1 and a second communication device 2.

[0013] The communication system 100 includes a first communication device 1, a second communication device 2, a third communication device 3, a first relay device 4, a second relay device 5, and a gateway 6. The devices constitute a communication network.

[0014] The first communication device 1 is a communication device mounted on a target vehicle 10, which is a predetermined vehicle, and capable of wireless communication. The first communication device 1 is, for example, a communication device capable of short-range wireless communication in accordance with the Wi-Fi standard. Wi-Fi is a registered trademark. The second communication device 2 is, for example, an application server. The gateway 6 is an access point for the first communication device 1 to connect to the cloud. In the communication system 100, when the first communication device 1 communicates with the second communication device 2, communication must go through the gateway 6. The gateway 6, the second communication device 2, and the third communication device 3 are communication devices installed outside the vehicle and connected to the cloud.

[0015] Here, there are cases where the first communication device 1 cannot communicate with the second communication device 2 directly via the gateway 6, such as when the distance between the first communication device 1 and the gateway 6 is far, or when there is an obstacle between the first communication device 1 and the gateway 6 and radio waves cannot reach the first communication device 1 and the gateway 6. In such cases, it is considered that the first communication device 1 communicates with the second communication device 2 also via a relay device located between the first communication device 1 and the gateway 6. In the communication system 100, the first communication device 1 communicates with the second communication device 2 using the first relay device 4 and the second relay device 5 as relay devices.

[0016] The first relay 4 is a communication device mounted on a first vehicle 40, which is a vehicle different from the target vehicle 10, and capable of wireless communication. The second relay 5 is a communication device mounted on a second vehicle 50, which is a vehicle different from the target vehicle 10 and the first vehicle 40, and capable of wireless communication. The first relay 4 and the second relay 5 are, for example, communication devices capable of short-range wireless communication in accordance with the Wi-Fi standard. The first relay 4 and the second relay 5 also have functions similar to those of the first communication device 1. More specifically, both the first relay 4 and the second relay 5 function as communication devices that allow the first vehicle 40 and the second vehicle 50 to transmit their own data to the second communication device 2, except when relaying is necessary. In other words, neither the first relay 4 nor the second relay 5 is a device that always relays when the first communication device 1 communicates with the second communication device 2. When the first relay device 4 and the second relay device 5 are not being used as normal communication devices, such as when the first vehicle 40 and the second vehicle 50 are parked, and it is necessary to relay data for other vehicles, the first relay device 4 and the second relay device 5 are utilized as relay devices.

[0017] A first communication path through which the first communication device 1 communicates with the second communication device 2 via the first relay device 4 and the gateway 6, and a second communication path through which the first communication device 1 communicates with the second communication device 2 via the second relay device 5 and the gateway 6 are configured in parallel. In other words, the first communication path is a communication path through which communication with the second communication device 2 is via the first relay device 4 without passing through the second relay device 5. The second communication path is a communication path through which communication with the second communication device 2 is via the second relay device 5 without passing through the first relay device 4.

[0018] The first relay device 4 and the second relay device 5 also have a sleep function and a wake-up function. The sleep function is a function that stops the communication function of the relay device. When the relay device is in sleep mode, power is not supplied to operate the communication function, so power consumption is reduced compared to when the communication function is not stopped. The wake-up function is a function that performs processing to resume the communication function that was stopped by the sleep function. In other words, the wake-up function is a function that transitions the relay device from a sleep state to a normal state.

[0019] The first vehicle 40 and the second vehicle 50 are electric vehicles. Hereinafter, a vehicle equipped with a relay device, such as the first vehicle 40 or the second vehicle 50, may be simply referred to as a relay vehicle.

[0020] 2, the first communication device 1 functions as a microcomputer including a CPU 11 and a memory 12. The memory 12 stores programs that enable the CPU 11 to execute predetermined functions.

[0021] The first communication device 1 realizes the functions of the following units by executing the programs in the memory 12. That is, the first communication device 1 has the functions of a startup information acquisition unit 13, a route control unit 14, and a data transmission / reception unit 15.

[0022] The activation information acquisition unit 13 requests the third communication device 3 to acquire time slot information and acquires the time slot information from the third communication device 3. The time slot information is information that assigns one of the relay devices provided in each relay vehicle to each of a plurality of pre-set time slots. In other words, the time slot information is information indicating the time and duration at which each relay device is capable of communication. The time slot information is registered in the slot table 35. In the time slot information, the time slots are set so that the time and duration at which each relay device is capable of communication do not overlap. For example, the time slot information shown in FIG. 3A has five time slots, slot numbers (i) to (v). The first vehicle 40 is assigned to slot number (i), and the second vehicle 50 is assigned to slot number (ii). Furthermore, a third vehicle different from the first vehicle 40 and the second vehicle 50 is assigned to slot number (iii), and no relay vehicle has yet been assigned to slot numbers (iv) and (v). When a new relay vehicle is registered in the time slot information, it is assigned to an empty slot that has no relay vehicle assigned. In the time slot information shown in FIG. 3A , as shown in FIG. 3B , relay vehicles (in other words, relay devices) associated with slot numbers (i) to (v) sequentially execute the relay function. Furthermore, the relay vehicles (in other words, relay devices) repeatedly execute the relay function, with slot numbers (i) to (v) forming one cycle. As an example, one time frame is approximately 3 seconds, and one cycle is set to approximately 15 seconds (3 seconds x 5). Note that if there are no relay vehicles assigned to slot numbers (iv) and (v), the number of time frames may be reduced, and slot numbers (i) to (iii) may be executed as one cycle.

[0023] In this embodiment, as shown in FIG. 1 , the first vehicle 40 and the second vehicle 50 constitute the communication system 100 as relay vehicles, and therefore the activation information acquisition unit 13 acquires first activation information and second activation information as time slot information. The first activation information is information indicating the time and duration at which the first relay device 4 becomes capable of communication. The second activation information is information indicating the time and duration at which the second relay device 5 becomes capable of communication. Hereinafter, the first activation information and the second activation information may be simply referred to as activation information.

[0024] Returning to FIG. 2 , the route control unit 14 controls which relay device the first communication device 1 communicates with. Specifically, the route control unit 14 instructs the data transceiver unit 15 which relay device to communicate with based on the time slot information input from the startup information acquisition unit 13. That is, the route control unit 14 controls communication with each relay device only when the relay device is within a communication-enabled time period. The route control unit 14 controls communication with the second communication device 2 using the first communication path during the communication-enabled time period for the first relay device 4, and controls communication with the second communication device 2 using the second communication path during the communication-enabled time period for the second relay device 5. Because the time and period when the first relay device 4 is available for communication do not overlap with the time and period when the second relay device 5 is available for communication, the route control unit 14 instructs the data transceiver unit 15 which relay device to communicate with. That is, the first communication device 1 communicates with the second communication device 2 using both the first communication path and the second communication path.

[0025] The data transmitter / receiver 15, in accordance with instructions from the route control unit 14, transmits the data a, b, c, and d stored in the buffer 16 to the first relay device 4 and the second relay device 5. The data transmitter / receiver 15 also stores the data a, b, c, and d received from the first relay device 4 and the second relay device 5 in the buffer 16. The timing at which the data transmitter / receiver 15 transmits and receives the data a, b, c, and d will be described in detail later.

[0026] The configuration of the second communication device 2 is similar to the configuration of the first communication device 1. The memory 12 of the second communication device 2 also stores programs that allow the CPU 11 to execute various applications.

[0027] [1-2-2. Configuration of the First Relay Device and the Second Relay Device] The first relay device 4 and the second relay device 5 function as a microcomputer including a CPU 41 and a memory 42. The memory 42 stores a program that enables the CPU 41 to execute predetermined functions.

[0028] The first relay device 4 and the second relay device 5 realize the functions of the following units by executing the programs in the memory 42. That is, the first relay device 4 and the second relay device 5 have the functions of a parking determination unit 43, a charging determination unit 44, a quality acquisition unit 45, a startup information acquisition unit 46, a startup control unit 47, and a data transmission / reception unit 48.

[0029] The first relay device 4 will be described in detail below.

[0030] The parking determination unit 43 determines whether or not the first vehicle 40 is parked. Specifically, the parking determination unit 43 determines that the first vehicle 40 is parked when the ignition switch of the first vehicle 40 is turned off.

[0031] The charging determination unit 44 determines whether the first vehicle 40 is being charged. Specifically, when a charging plug is connected to the first vehicle 40, the charging determination unit 44 determines that the first vehicle 40 is being charged.

[0032] The quality acquisition unit 45 acquires the quality of wireless communication. More specifically, the quality acquisition unit 45 acquires the communication quality of the first communication path. Specifically, the quality acquisition unit 45 acquires the strength of radio waves input to a communication antenna provided in the first relay 4. In other words, the quality acquisition unit 45 acquires the quality of wireless communication with the gateway 6. Note that the quality acquisition unit 45 may acquire the communication speed with the gateway 6 as the communication quality of the first communication path.

[0033] The startup information acquisition unit 46 inquires of the third communication device 3 about time slot information and acquires first startup information from the third communication device 3. More specifically, the startup information acquisition unit 46 inquires of the third communication device 3 about time slot information at the time when the first vehicle 40 is parked, based on the information about whether the first vehicle 40 is parked or not input from the parking determination unit 43. At the same time, the startup information acquisition unit 46 notifies the third communication device 3 of the information about whether the first vehicle 40 is charging or not input from the charging determination unit 44 and the information about the quality of wireless communication input from the quality acquisition unit 45.

[0034] The startup control unit 47 operates the first relay 4 based on the first startup information input from the startup information acquisition unit 46. Specifically, the startup control unit 47 controls the on / off of the communication function of the first relay 4. That is, the startup control unit 47 wakes up the communication function of the first relay 4 at the time specified in the first startup information. Furthermore, the startup control unit 47 puts the communication function of the first relay 4 to sleep when the time specified in the first startup information has elapsed since the time specified in the first startup information.

[0035] The data transmitter / receiver 48 relays data received from the first communication device 1 to the second communication device 2. The data transmitter / receiver 48 also relays data received from the second communication device 2 to the first communication device 1. At this time, the data transmitter / receiver 48 relays the data based on the control of the startup control unit 47. In other words, the data transmitter / receiver 48 relays data when the communication function of the first relay device 4 is awake, and does not relay data when the communication function of the first relay device 4 is asleep.

[0036] The second relay 5 is configured in the same manner as the first relay 4, except that the first vehicle 40 is replaced with the second vehicle 50, the first activation information is replaced with the second activation information, and the first communication path is replaced with the second communication path.

[0037] [1-2-3. Configuration of the Third Communication Device] The third communication device 3 is a communication device for managing time slot information.

[0038] The third communication device 3 functions as a microcomputer including a CPU 31 and a memory 32. The memory 32 stores programs that allow the CPU 31 to execute predetermined functions.

[0039] The third communication device 3 realizes the functions of the following units by executing the programs in the memory 32. That is, the third communication device 3 has the functions of an allocation unit 33 and an inquiry unit 34.

[0040] When the activation information acquisition unit 46 inquires about the time slot information, the allocation unit 33 sets the activation information and notifies the activation information acquisition unit 46. Specifically, as shown in FIG. 3A , the allocation unit 33 allocates the relay vehicle for which the time slot information has been inquired to one of a plurality of time slots. The allocated information is registered in the slot table 35. In this embodiment, when the first vehicle 40 inquires about the time slot information, the allocation unit 33 sets first activation information and notifies the first vehicle 40 of the first activation information. Furthermore, when the second vehicle 50 inquires about the time slot information, the allocation unit 33 sets second activation information and notifies the second vehicle 50 of the second activation information. At this time, the allocation unit 33 sets the first activation information and the second activation information so that the time and time when the first relay 4 becomes capable of communication do not overlap with the time and time when the second relay 5 becomes capable of communication.

[0041] The allocation unit 33 also determines whether the communication quality of the communication path through which the relay device relays data is good. If the allocation unit 33 determines that the communication quality of the communication path is good, it allocates time frames of the time slot information so that the relay device can communicate for a longer period of time compared to when it determines that the communication quality of the communication path is poor. More specifically, the allocation unit 33 determines the allocation of time slot information based on information on the quality of wireless communication input from the startup information acquisition unit 46. Specifically, if the radio wave strength is equal to or greater than a predetermined strength, the allocation unit 33 determines that the communication quality of the communication path is good. Then, the allocation unit 33 allocates two or more time frames of the time slot information. On the other hand, if the radio wave strength is weaker than the predetermined strength, the allocation unit 33 sets a shorter time frame than the time slot information as the communication available time. Note that if the radio wave strength is weaker than the predetermined strength, the allocation unit 33 does not need to allocate any time frames of the time slot information.

[0042] Furthermore, when the relay vehicle is charging, the allocation unit 33 allocates time frames of the time slot information so that the relay device can communicate for a longer period of time compared to when the relay vehicle is not charging. More specifically, the allocation unit 33 determines the allocation of time slot information based on the information on whether the relay vehicle is charging or not input from the startup information acquisition unit 46. Specifically, the allocation unit 33 allocates two or more time frames of the time slot information.

[0043] 3A , the allocation unit 33 may allocate different numbers of time slots to different relay vehicles, such as allocating the first vehicle 40 to slot numbers (i) to (iii) and the second vehicle 50 to slot number (iv).

[0044] When there is a request to acquire time slot information from the first communication device 1 or the second communication device 2, the inquiry unit 34 inquires about the time slot information registered in the slot table 35 and notifies the time slot information to the first communication device 1 or the second communication device 2. In this embodiment, the inquiry unit 34 notifies the first communication device 1 or the second communication device 2 of the first startup information and the second startup information.

[0045] [1-2. Processing] [1-2-1. Relay Device Processing] The processing when the first relay device 4 and the second relay device 5 inquire about time slot information from the third communication device 3 will be described using the sequence diagram of Fig. 4. This processing assumes a situation in which the first vehicle 40 and the second vehicle 50 are parked in, for example, a parking lot of a shopping mall.

[0046] First, in S101, the first relay device 4 determines whether or not the first vehicle 40 has been parked.

[0047] When the first relay device 4 determines in S101 that the first vehicle 40 has parked, in S102, the first relay device 4 inquires of the third communication device 3 about time slot information.

[0048] Next, in S103, the third communication device 3 determines the first activation information.

[0049] Next, in S104, the third communication device 3 notifies the first relay device 4 of the first startup information.

[0050] Next, in S105, the first relay device 4 sleeps based on the first startup information until the time when the first relay device 4 becomes capable of communication.

[0051] Subsequently, in S106, the second relay device 5 determines whether or not the second vehicle 50 has been parked.

[0052] When the second relay device 5 determines in S106 that the second vehicle 50 has parked, in S107, the second relay device 5 inquires of the third communication device 3 about time slot information.

[0053] Next, in S108, the third communication device 3 determines the second activation information.

[0054] Subsequently, in S109 , the third communication device 3 notifies the second relay device 5 of the second startup information.

[0055] Next, in S110, the second relay device 5 sleeps based on the second startup information until the time when the second relay device 5 becomes capable of communication.

[0056] [1-2-2. Processing when transmitting data from the first communication device to the second communication device] The processing when the first communication device 1 transmits data to the second communication device 2 via a relay device will be described using the sequence diagram of FIG. 5. This processing will be described on the assumption that the first relay device 4, the second relay device 5, and the third relay device 7 are registered in the time slot information. This processing assumes, for example, a situation in which the first communication device 1 transmits probe information of the target vehicle 10 to the second communication device 2.

[0057] First, in S201, the first communication device 1 inquires about time slot information from the third communication device 3. More specifically, the first communication device 1 inquires about time slot information from the third communication device 3 via one of the relay devices equipped in surrounding vehicles. As an example, the first communication device 1 simultaneously broadcasts information indicating that it wishes to inquire about time slot information from the third communication device 3 to multiple relay devices in the vicinity. Then, one of the relay devices that receives the information relays the information to the third communication device 3.

[0058] Next, in S202, the third communication device 3 checks the time slot information registered in the slot table 35.

[0059] Next, in S203, the third communication device 3 notifies the first communication device 1 of the time slot information. As an example, the third communication device 3 transmits the time slot information to the relay device that relayed the information in S201, and the relay device then transmits the time slot information to the first communication device 1. In this embodiment, the third communication device 3 notifies the first communication device 1 of the first startup information associated with the first relay device 4, the second startup information associated with the second relay device 5, and the third startup information associated with the third relay device 7. That is, before transmitting data to the second communication device 2, the first communication device 1 obtains the first startup information, the second startup information, and the third startup information from the third communication device 3. Then, based on the first startup information, the second startup information, and the third startup information, the first communication device 1 recognizes the time and time at which the first relay device 4, the second relay device 5, and the third relay device 7 become capable of communication.

[0060] Next, in S204, the time comes when the first relay device 4 is ready to communicate, and the first relay device 4 wakes up.

[0061] The first communication device 1 is aware of the time when the first relay device 4 will be able to communicate, and therefore in S205 transmits data a to the first relay device 4. Subsequently, in S206, the first relay device 4 transmits data a to the second communication device 2.

[0062] The first communication device 1 recognizes that the first relay device 4 is still within the communication available time, so in S207 it transmits data b to the first relay device 4. Then, in S208, the first relay device 4 transmits data b to the second communication device 2. After this, the first relay device 4 goes to sleep because the communication available time set in the first startup information has elapsed.

[0063] Subsequently, in S209, the time comes when the second relay device 5 is ready to communicate, and the second relay device 5 wakes up.

[0064] The first communication device 1 is aware of the time when the second relay device 5 will be able to communicate, and therefore in S210 transmits data c to the second relay device 5. Subsequently, in S211, the second relay device 5 transmits data c to the second communication device 2.

[0065] The first communication device 1 recognizes that the second relay device 5 is still within the communication available time, and therefore in S212 transmits data d to the second relay device 5. Subsequently, in S213, the second relay device 5 transmits data d to the second communication device 2. After this, the second relay device 5 goes to sleep because the communication available time set in the second startup information has elapsed.

[0066] Next, in S214, the time comes when the third relay device 7 is ready to communicate, and the third relay device 7 wakes up.

[0067] The first communication device 1 is aware of the time when the third relay device 7 will be able to communicate, and therefore in S215 transmits data e to the third relay device 7. Subsequently, in S216, the third relay device 7 transmits data e to the second communication device 2.

[0068] The first communication device 1 recognizes that the third relay device 7 is still within the communication available time, and therefore in S217 transmits data f to the third relay device 7. Subsequently, in S218, the third relay device 7 transmits data f to the second communication device 2. After this, the third relay device 7 goes to sleep because the communication available time set in the third startup information has elapsed.

[0069] If the first communication device 1 wishes to transmit further data to the second communication device 2, steps S204 to S218 of this process are repeated.

[0070] [1-2-3. Processing When the First Communication Device Receives Data from the Second Communication Device] The processing when the first communication device 1 receives data from the second communication device 2 via a relay device will be described using the sequence diagram of FIG. 6. This processing will be described on the assumption that the first relay device 4, the second relay device 5, and the third relay device 7 are registered in the time slot information. This processing assumes, for example, a situation in which the first communication device 1 receives software update information or video data from the second communication device 2.

[0071] First, in S301, the second communication device 2 inquires of the third communication device 3 about time slot information.

[0072] Next, in S302, the third communication device 3 checks the time slot information registered in the slot table 35.

[0073] Next, in S303, the third communication device 3 notifies the second communication device 2 of the time slot information. In this embodiment, the third communication device 3 notifies the second communication device 2 of the first startup information associated with the first relay 4, the second startup information associated with the second relay 5, and the third startup information associated with the third relay 7. In other words, the second communication device 2 obtains the first startup information, the second startup information, and the third startup information from the third communication device 3 before transmitting data to the first communication device 1. Then, based on the first startup information, the second startup information, and the third startup information, the second communication device 2 recognizes the time and time at which the first relay 4, the second relay 5, and the third relay 7 become able to communicate.

[0074] Next, in S304, the time comes when the first relay device 4 is ready to communicate, and the first relay device 4 wakes up.

[0075] The second communication device 2 is aware of the time when the first relay device 4 will be able to communicate, and therefore in S305 transmits data a to the first relay device 4. Subsequently, in S306, the first relay device 4 transmits data a to the first communication device 1.

[0076] The second communication device 2 recognizes that the first relay device 4 is still within the communication available time, and therefore in S307 transmits data b to the first relay device 4. Next, in S308, the first relay device 4 transmits data b to the first communication device 1. After this, the first relay device 4 goes to sleep because the communication available time set in the first startup information has elapsed.

[0077] Next, in S309, the time comes when the second relay device 5 is ready to communicate, and the second relay device 5 wakes up.

[0078] The second communication device 2 is aware of the time when the second relay device 5 will be able to communicate, and therefore in S310 transmits data c to the second relay device 5. Subsequently, in S311, the second relay device 5 transmits data c to the first communication device 1.

[0079] The second communication device 2 recognizes that the second relay device 5 is still within the communication available time, and therefore in S312 transmits data d to the second relay device 5. Subsequently, in S313, the second relay device 5 transmits data d to the first communication device 1. After this, the second relay device 5 goes to sleep because the communication available time set in the second startup information has elapsed.

[0080] Next, in S314, the time comes when the third relay device 7 is ready to communicate, and the third relay device 7 wakes up.

[0081] The second communication device 2 is aware of the time when the third relay device 7 will be able to communicate, and therefore in S315 transmits data e to the third relay device 7. Subsequently, in S316, the third relay device 7 transmits data e to the first communication device 1.

[0082] The second communication device 2 recognizes that the third relay device 7 is still within the communication available time, and therefore in S317 transmits data f to the third relay device 7. Subsequently, in S318, the third relay device 7 transmits data f to the first communication device 1. After this, the third relay device 7 goes to sleep because the communication available time set in the third startup information has elapsed.

[0083] If the second communication device 2 wishes to transmit further data to the first communication device 1, steps S304 to S318 of this process are repeated.

[0084] [1-3. Effects] According to the embodiment described above in detail, the following effects can be obtained.

[0085] (1a) In the communication system 100, the first communication device 1 communicates with the second communication device 2 using both a first communication path, which is a communication path for communicating with the second communication device 2 via the first relay device 4 without passing through the second relay device 5, and a second communication path, which is a communication path for communicating with the second communication device 2 via the second relay device 5 without passing through the first relay device 4. With this configuration, in the communication system 100, multiple relay devices are connected in parallel. This prevents the communication load from concentrating on one relay device compared to a communication system in which only one communication path is used and one relay device is constantly communicating. Therefore, each relay device can consume less power than when the communication load is concentrated.

[0086] (1b) In the communication system 100, the second relay device 5 is asleep when the first communication device 1 is communicating using the first communication path, and the first relay device 4 is asleep when the first communication device 1 is communicating using the second communication path. With this configuration, the first relay device 4 and the second relay device 5 alternately communicate as relay devices. Because the relay device sleeps when not relaying data, the power consumption of the relay device can be reduced compared to a configuration in which the relay device is awake even when not relaying data. Furthermore, even if the data transmitted and received by the first communication device 1 is large, the first communication device 1 can divide the data and transmit and receive it. Each relay device can also take turns relaying the divided data. Therefore, compared to a case in which one relay device relays a large amount of data, the concentration of the communication load on one relay device can be suppressed. Therefore, each relay device can consume less power compared to a case in which the communication load is concentrated.

[0087] (1c) In the communication system 100, the third communication device 3 sets the first startup information and the second startup information so that the time and period when the first relay device 4 becomes capable of communication do not overlap with the time and period when the second relay device 5 becomes capable of communication. With this configuration, the time during which the first communication device 1 can transmit and receive data is the sum of the time during which the first relay device 4 becomes capable of communication and the time during which the second relay device 5 becomes capable of communication. In other words, the time during which the first communication device 1 can transmit and receive data is longer than when the time and period when the first relay device 4 becomes capable of communication overlaps with the time and period when the second relay device 5 becomes capable of communication. This improves the wireless utilization rate in the communication system 100.

[0088] (1d) In the communication system 100, when the first vehicle 40 is parked, the first relay 4 inquires of the third communication device 3 about the time slot information. According to this configuration, the first relay 4 inquires of the third communication device 3 about the time slot information at a timing when the first relay 4 can be used as a relay. Therefore, the first relay 4 can be efficiently used as a relay.

[0089] (1e) In the communication system 100, the first communication device 1 inquires about time slot information before transmitting data to the second communication device 2, and uses the first communication path during the time when the first relay device 4 is available for communication, and uses the second communication path during the time when the second relay device 5 is available for communication. With this configuration, the first communication device 1 can recognize when and to which relay device to transmit data, and therefore can transmit data smoothly.

[0090] (1f) In the communication system 100, the second communication device 2 inquires about time slot information before transmitting data to the first communication device 1, and uses the first communication path during the time when the first relay device 4 is available for communication, and the second communication path during the time when the second relay device 5 is available for communication. With this configuration, the second communication device 2 can recognize when and to which relay device to transmit data, and can transmit data smoothly.

[0091] (1g) In the communication system 100, when the third communication device 3 determines that the communication quality of the communication path is good, it sets the relay device to have a longer communication time. On the other hand, when the third communication device 3 determines that the communication quality of the communication path is poor, it sets the relay device to have a shorter communication time. With this configuration, the communication time of a relay device that can transmit and receive data at high speed is long, while the communication time of a relay device that can only transmit and receive data at low speed is short. Therefore, the first communication device 1 and the second communication device 2 can transmit and receive data efficiently. For example, when the communication quality of the first communication path is determined to be good and the communication quality of the second communication path is determined to be poor, the communication time of the first relay device 4 of the first vehicle 40 may be set to be different from the communication time of the second relay device 5 of the second vehicle 50, as shown in FIG. 7 . Even in this case, the communication time of the entire communication system 100 is the sum of the communication time of the first relay device 4 and the communication time of the second relay device 5, so that the communication time in the communication system 100 is sufficiently guaranteed.

[0092] (1h) In the communication system 100, the third communication device 3 sets the relay device to be able to communicate for a longer period of time when the relay vehicle is charging. With this configuration, the relay device is set to be able to communicate for a longer period of time when there is power consumption margin. Therefore, the relay device can be used efficiently.

[0093] [1-4. Correspondence] In the above embodiment, the first communication device 1 corresponds to the vehicle communication device, and the third communication device corresponds to the control communication device.

[0094] [2. Other Embodiments] Although the embodiments of the present disclosure have been described above, it goes without saying that the present disclosure is not limited to the above-described embodiments and can take on various forms.

[0095] (3a) In the above embodiment, the relay device has a sleep function and a wake-up function. However, the relay device does not have to have the sleep function and the wake-up function. In other words, the relay device does not have to sleep outside of communication available times. Even in this case, since the first communication device 1 uses multiple communication paths, it is possible to prevent the communication load from concentrating on a single relay device compared to a communication system in which only one communication path is used and one relay device is constantly communicating. Therefore, each relay device can reduce power consumption compared to when the communication load is concentrated.

[0096] (3b) In the above embodiment, the vehicle equipped with the relay device is an electric vehicle. However, the vehicle equipped with the relay device does not have to be an electric vehicle. Of the multiple vehicles equipped with relay devices, only some of the vehicles may be electric vehicles.

[0097] (3c) In the above embodiment, the configuration in which there are two or three relay devices is illustrated. However, the number of relay devices may be four or more. In other words, the number of communication paths through which the first communication device 1 can communicate with the second communication device 2 may be two, three, or more.

[0098] (3d) Each device described in this disclosure (i.e., the first communication device 1, the second communication device 2, the third communication device 3, and the relay device) and the method by each device may be implemented by a special-purpose computer provided by configuring a processor and memory programmed to execute one or more functions embodied in a computer program. Alternatively, each device described in this disclosure and the method by each device may be implemented by a special-purpose computer provided by configuring a processor with one or more dedicated hardware logic circuits. Alternatively, each device described in this disclosure and the method by each device may be implemented by one or more special-purpose computers configured by combining a processor and memory programmed to execute one or more functions with a processor configured with one or more hardware logic circuits. Furthermore, the computer program may be stored as instructions executed by a computer on a computer-readable non-transitory tangible recording medium. The method for implementing the functions of each unit included in each device does not necessarily need to include software; all of the functions may be implemented using one or more hardware.

[0099] (3e) The functions of one component in the above embodiments may be distributed among multiple components, or the functions of multiple components may be integrated into one component. Also, part of the configuration of the above embodiments may be omitted. Furthermore, at least part of the configuration of the above embodiments may be added to or substituted for the configuration of another of the above embodiments.

[0100] (3f) In addition to the communication system 100 described above, the present disclosure can also be realized in various forms, such as each device that constitutes the communication system 100, a program for causing a computer to function as each device, a non-transient physical recording medium such as a semiconductor memory on which the program is recorded, and a communication method.

[0101] [Technical Ideas Disclosed in the Present Specification] [Item 1] A communication system (100) for communication between a first communication device (1) and a second communication device (2), comprising: the first communication device, the second communication device, a first relay device (4), and a second relay device (5), wherein the first communication device is a communication device mounted on a target vehicle (10) that is a predetermined vehicle and capable of wireless communication; the first relay device is a communication device mounted on a first vehicle (40) that is a vehicle different from the target vehicle and capable of wireless communication; and the second relay device is a communication device mounted on a second vehicle (50) that is a vehicle different from the target vehicle and the first vehicle and capable of wireless communication. a communication system in which the first communication device is configured to communicate with the second communication device using a first communication path, which is a communication path for communicating with the second communication device via the first relay device without passing through the second relay device, and a second communication path, which is a communication path for communicating with the second communication device via the second relay device without passing through the first relay device (14, S205, S207, S210, S212).

[0102] [Item 2] The communication system according to item 1, further comprising a third communication device (3), wherein the first relay device operates in accordance with first activation information indicating the time and duration when the first relay device will be able to communicate (47, S204, S206, S208), the second relay device operates in accordance with second activation information indicating the time and duration when the second relay device will be able to communicate (47, S209, S211, S213), the third communication device is a communication device installed outside the vehicle and for managing the first activation information and the second activation information, and the third communication device sets the first activation information and the second activation information, and at this time, prevents the time and duration when the first relay device will be able to communicate from overlapping with the time and duration when the second relay device will be able to communicate (33).

[0103] [Item 3] The communication system according to Item 2, wherein the first relay device requests the first activation information from the third communication device when the first vehicle is parked (S102), and the third communication device is configured to transmit the first activation information to the first relay device in response to the request from the first relay device (S104).

[0104] [Item 4] The communication system according to item 2 or 3, wherein the first communication device acquires the first startup information and the second startup information from the third communication device before transmitting data to the second communication device, and recognizes, based on the first startup information and the second startup information, the time and duration at which the first relay device and the second relay device are able to communicate (S201), and uses the first communication path during the time at which the first relay device is able to communicate, and the second communication path during the time at which the second relay device is able to communicate (S14, S205, S207, S210, S212).

[0105] [Item 5] The communication system according to any one of items 2 to 4, wherein the second communication device acquires the first startup information and the second startup information from the third communication device before transmitting data to the first communication device, and recognizes, based on the first startup information and the second startup information, the time and duration at which the first relay device and the second relay device are able to communicate (S301), and uses the first communication path during the time at which the first relay device is able to communicate, and the second communication path during the time at which the second relay device is able to communicate (S14, S305, S307, S310, S312).

[0106] [Item 6] The communication system according to any one of items 2 to 5, wherein the third communication device determines whether the communication quality of the first communication path is good, and when it is determined that the communication quality of the first communication path is good, sets the first startup information so that the time during which the first relay device is able to communicate is longer compared to when it is determined that the communication quality of the first communication path is not good (33).

[0107] [Item 7] The communication system according to any one of Items 2 to 6, wherein the first vehicle is an electric vehicle, and the third communication device sets the first startup information (33) when the first vehicle is being charged so that the first relay device is capable of communicating for a longer period of time compared to when the first vehicle is not being charged.

[0108] [Item 8] A vehicle communication device (1) is used in a communication system capable of wireless communication and capable of communicating with another communication device (2) via a first relay device (4) and a second relay device (5), and is mounted on a target vehicle (10) that is a predetermined vehicle, wherein the first relay device is mounted on a first vehicle (40) that is a vehicle different from the target vehicle and is capable of wireless communication, and the second relay device is mounted on a second vehicle (50) that is a vehicle different from the target vehicle and the first vehicle and is capable of wireless communication, and the vehicle communication device is configured to communicate with the other communication device by using both a first communication path that is a communication path for communicating with the other communication device via the first relay device without passing through the second relay device, and a second communication path that is a communication path for communicating with the other communication device via the second relay device without passing through the first relay device (14, S205, S207, S210, S212).

[0109] [Item 9] A relay device (4, 5) capable of wireless communication, used in a communication system for a vehicle communication device (1) to communicate with another communication device (2), and mounted on a vehicle (40, 50), wherein the vehicle communication device is mounted on a target vehicle (10) that is a vehicle different from the vehicle, is a communication device capable of wireless communication, and communicates with the other communication device using a first communication path that is a communication path for communicating with the other communication device via the relay device, and a second communication path that is a communication path for communicating with the other communication device via another relay device without passing through the relay device (14, S205, S207, S210, S212), and the relay device operates in accordance with startup information that is information indicating a time and duration when the relay device is capable of communication (47), and the relay device is configured so that the time and duration when the relay device is capable of communication do not overlap with the time and duration when the other relay device is capable of communication.

[0110] [Item 10] A control communication device (3) used in a communication system in which a vehicle communication device (1) can communicate with another communication device (2) via a first relay device (4) and a second relay device (5), wherein the vehicle communication device is mounted on a target vehicle (10) that is a predetermined vehicle and is a communication device capable of wireless communication, the first relay device is mounted on a first vehicle (40) that is a vehicle different from the target vehicle and is a communication device capable of wireless communication, and operates in accordance with first activation information (47) that is information indicating the time and duration at which the first relay device becomes capable of communication, and the second relay device is mounted on a second vehicle (50) that is a vehicle different from the target vehicle and the first vehicle and is a communication device capable of wireless communication, and operates in accordance with second activation information (47) that is information indicating the time and duration at which the second relay device becomes capable of communication, The vehicle communication device communicates with the control communication device using a first communication path, which is a communication path for communicating with the other communication device via the first relay device without passing through the second relay device, and a second communication path, which is a communication path for communicating with the other communication device via the second relay device without passing through the first relay device (14, S205, S207, S210, S212), and the control communication device sets the first startup information and the second startup information, and is configured so that the time and period when the first relay device is able to communicate do not overlap with the time and period when the second relay device is able to communicate (33).

Claims

1. A communication system (100) for communication between a first communication device (1) and a second communication device (2), comprising the first communication device, the second communication device, a first relay device (4), and a second relay device (5), wherein the first communication device is a communication device mounted on a target vehicle (10) that is a predetermined vehicle and capable of wireless communication, the first relay device is a communication device mounted on a first vehicle (40) that is a vehicle different from the target vehicle and capable of wireless communication, and the second relay device is a communication device mounted on a second vehicle (50) that is a vehicle different from the target vehicle and the first vehicle and capable of wireless communication, a communication system in which the first communication device is configured to communicate with the second communication device using a first communication path, which is a communication path for communicating with the second communication device via the first relay device without passing through the second relay device, and a second communication path, which is a communication path for communicating with the second communication device via the second relay device without passing through the first relay device (14, S205, S207, S210, S212).

2. A communication system as claimed in claim 1, further comprising a third communication device (3), wherein the first relay device operates in accordance with first activation information which is information indicating the time and duration at which the first relay device will be able to communicate (47, S204, S206, S208), the second relay device operates in accordance with second activation information which is information indicating the time and duration at which the second relay device will be able to communicate (47, S209, S211, S213), the third communication device is a communication device installed outside the vehicle for managing the first activation information and the second activation information, and the third communication device sets the first activation information and the second activation information, in such a way that the time and duration at which the first relay device will be able to communicate and the time and duration at which the second relay device will be able to communicate do not overlap (33).

3. A communication system as described in claim 2, wherein the first relay device requests the first activation information from the third communication device when the first vehicle is parked (S102), and the third communication device is configured to transmit the first activation information to the first relay device in response to the request from the first relay device (S104).

4. A communication system as claimed in claim 2 or 3, wherein the first communication device acquires the first startup information and the second startup information from the third communication device before transmitting data to the second communication device, and recognizes, based on the first startup information and the second startup information, the time and duration at which the first relay device will be able to communicate and the time and duration at which the second relay device will be able to communicate (S201), and uses the first communication path during the time at which the first relay device is able to communicate, and the second communication path during the time at which the second relay device is able to communicate (14, S205, S207, S210, S212).

5. A communication system according to claim 2 or 3, wherein the second communication device acquires the first startup information and the second startup information from the third communication device before transmitting data to the first communication device, and recognizes, based on the first startup information and the second startup information, the time and duration at which the first relay device will be able to communicate and the time and duration at which the second relay device will be able to communicate (S301), and uses the first communication path during the time at which the first relay device will be able to communicate, and the second communication path during the time at which the second relay device will be able to communicate (14, S305, S307, S310, S312).

6. A communication system as described in claim 2 or claim 3, wherein the third communication device determines whether the communication quality of the first communication path is good, and if it determines that the communication quality of the first communication path is good, sets the first startup information so that the time during which the first relay device is able to communicate is longer compared to when it determines that the communication quality of the first communication path is not good (33).

7. A communication system as described in claim 2 or claim 3, wherein the first vehicle is an electric vehicle, and the third communication device sets the first startup information so that, when the first vehicle is being charged, the first relay device is able to communicate for a longer period of time than when the first vehicle is not being charged (33).

8. A vehicle communication device (1) used in a communication system capable of wireless communication and capable of communicating with another communication device (2) via a first relay device (4) and a second relay device (5), the vehicle communication device being mounted on a target vehicle (10) that is a predetermined vehicle, wherein the first relay device is mounted on a first vehicle (40) that is a vehicle different from the target vehicle and is capable of wireless communication; the second relay device is mounted on a second vehicle (50) that is a vehicle different from the target vehicle and the first vehicle and is capable of wireless communication; the vehicle communication device is configured to communicate with the other communication device using both a first communication path that is a communication path for communicating with the other communication device via the first relay device without passing through the second relay device, and a second communication path that is a communication path for communicating with the other communication device via the second relay device without passing through the first relay device (14, S205, S207, S210, S212).

9. A relay device (4, 5) capable of wireless communication, used in a communication system for a vehicle communication device (1) to communicate with another communication device (2), and mounted on a vehicle (40, 50), wherein the vehicle communication device is mounted on a target vehicle (10) that is a vehicle different from the vehicle, is a communication device capable of wireless communication, and communicates with the other communication device using both a first communication path that is a communication path for communicating with the other communication device via the relay device, and a second communication path that is a communication path for communicating with the other communication device via another relay device without passing through the relay device (14, S205, S207, S210, S212), the relay device operates in accordance with startup information that is information indicating the time and duration at which the relay device is capable of communication (47), and the relay device is configured so that the time and duration at which the relay device is capable of communication do not overlap with the time and duration at which the other relay device is capable of communication.

10. A control communication device (3) used in a communication system in which a vehicle communication device (1) can communicate with another communication device (2) via a first relay device (4) and a second relay device (5), wherein the vehicle communication device is mounted on a target vehicle (10), which is a predetermined vehicle, and is a communication device capable of wireless communication; the first relay device is mounted on a first vehicle (40), which is a vehicle different from the target vehicle, and is a communication device capable of wireless communication, and operates in accordance with first activation information (47), which is information indicating the time and duration at which the first relay device becomes capable of communication; and the second relay device is mounted on a second vehicle (50), which is a vehicle different from the target vehicle and the first vehicle, and is a communication device capable of wireless communication, and operates in accordance with second activation information (47), which is information indicating the time and duration at which the second relay device becomes capable of communication. The vehicle communication device communicates with the control communication device using a first communication path, which is a communication path for communicating with the other communication device via the first relay device without passing through the second relay device, and a second communication path, which is a communication path for communicating with the other communication device via the second relay device without passing through the first relay device (14, S205, S207, S210, S212), and the control communication device sets the first startup information and the second startup information, and is configured so that the time and period when the first relay device is able to communicate do not overlap with the time and period when the second relay device is able to communicate (33).

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