Communication relay system and communication relay device

Abstract

A communication relay system according to the present invention comprises a first network, two first communication relay devices that relay data with a first wireless network and a second wireless network and are set to either an execution system or a standby system, a second network, and two second communication relay devices that relay data with the first wireless network and the second wireless network to the second network and are set to either the execution system or the standby system. The first communication relay device of the execution system relays data received from the first network to the first wireless network and the second wireless network, and the second communication relay device of the execution system relays data received from the first wireless network and the second wireless network to the second network.

Description

Communication relay system and communication relay device

[0001] The present invention relates to a communication relay system and a communication relay device.

[0002] With the advent of 5th generation mobile communication systems (5G), wireless communication has become possible with high-capacity and low-latency transmission, and its use in controlling vehicles such as automobiles and trains is being considered. In addition, by utilizing the public network lines of mobile communication carriers, there is the advantage of being able to reduce the costs of building and maintaining one's own dedicated lines.

[0003] However, when wireless communication is used to control vehicles, the communication bandwidth of wireless networks is narrower than that of wired networks, and congestion can cause packet loss or delays, which can make it impossible to control the vehicle. Conventionally, a method of duplicating wireless networks has been used to increase communication reliability.

[0004] Patent document 1 describes a duplex device that performs a process to "match information between the new operating device and the standby device when a failure occurs in the operating device and the standby device is switched to the new operating device (when duplex switching occurs)."

[0005] Japanese Patent Application Laid-Open No. 2001-014181

[0006] The duplexing device described in Patent Document 1 is a device that performs duplex control from a higher-level device to a lower-level device, and Patent Document 1 does not describe redundant control of a wireless network. Therefore, the technology described in Patent Document 1 cannot be applied to a vehicle control system that uses a wireless network.

[0007] The present invention has been made in view of the above circumstances, and has as its object to provide a communication relay system and a communication relay device that suppress the communication band within a wireless network.

[0008] A communication relay system according to the present invention relays data transmitted and received between a first network and a second network via a first wireless network and a second wireless network. The communication relay system includes: a first network and two first communication relay devices configured as either an active system or a standby system that relay data between the first wireless network and the second wireless network; and a second network and two second communication relay devices configured as either an active system or a standby system that relay data between the first wireless network and the second wireless network to the second network. The first communication relay device of the active system relays data received from the first network to the first wireless network and the second wireless network, the first communication relay device of the standby system does not relay data received from the first network to the first wireless network and the second wireless network, the second communication relay device of the active system relays data received from the first wireless network and the second wireless network to the second network, and the second communication relay device of the standby system does not relay data received from the first wireless network and the second wireless network to the second network.

[0009] According to the present invention, only the communication relay device of the execution system relays data to the first wireless network and the second wireless network in a duplicated manner, thereby reducing the communication bandwidth within the wireless network. Issues, configurations, and effects other than those described above will become clear from the description of the following embodiments.

[0010] 1 is a block diagram showing an example of the overall configuration of a conventional communication relay system. FIG. 2 is a block diagram showing an example of the configuration of a duplicated communication relay system according to an embodiment of the present invention. FIG. 3 is a block diagram showing an example of the internal configuration of a communication relay device according to an embodiment of the present invention. FIG. 4 is a block diagram showing an example of the hardware configuration of a computer according to an embodiment of the present invention. FIG. 5 is a block diagram showing an example of data flow during normal operation according to an embodiment of the present invention. FIG. 6 is a sequence diagram showing an example of operation of each device of the communication relay system during normal operation according to an embodiment of the present invention. FIG. 7 is a sequence diagram showing an example of operation of each device of the communication relay system when a failure occurs in the communication relay device according to an embodiment of the present invention. FIG. 8 is a sequence diagram showing an example of operation of each device of the communication relay system when a failure occurs in the communication relay device, which is an execution system according to an embodiment of the present invention. FIG. 9 is a sequence diagram showing an example of operation of each device of the communication relay system when the failure in the communication relay device according to an embodiment of the present invention is recovered from.

[0011] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In this specification and drawings, components having substantially the same functions or configurations are designated by the same reference numerals, and redundant description will be omitted.

[0012] <Configuration Example of a Conventional Communication Relay System> First, a configuration example of a conventional communication relay system 10 will be described with reference to Fig. 1. Fig. 1 is a block diagram showing an example of the overall configuration of the conventional communication relay system 10. The conventional communication relay system 10 is configured with a general wireless network that is duplicated.

[0013] The communication relay system 10 is composed of an in-vehicle network 20, a base station network 30, wireless terminals 111, 112, 113, and 114, and wireless networks 301 and 302.

[0014] The in-vehicle network 20 is a network in a single vehicle (not shown). The vehicle on which the in-vehicle network 20 is established is assumed to be a single automobile or a multi-car train. The blocks within the in-vehicle network 20 are information processing devices such as a personal computer (PC) or an electronic control unit (ECU). The in-vehicle network 20 includes a gateway 101 and a gateway 102 connected to wireless terminals 111 and 112.

[0015] The gateway 101 and the gateway 102 are connected to a wireless terminal 111 and a wireless terminal 112. The wireless terminal 111 and the wireless terminal 112 are both assumed to be access points. In FIG. 1 , the wireless terminal 111 and the wireless terminal 112 are depicted as being located away from the in-vehicle network 20, but in reality, the wireless terminal 111 and the wireless terminal 112 are configured to be included in the in-vehicle network 20.

[0016] The base station network 30 is a network established within one control station. The control station manages, for example, the current position and destination of a vehicle. The blocks within the base station network 30 are information processing devices such as a PC or a control console. The base station network 30 includes a gateway 103 and a gateway 104 connected to wireless terminals 113 and 114.

[0017] The gateway 103 and the gateway 104 are connected to the wireless terminal 113 and the wireless terminal 114. The wireless terminal 113 and the wireless terminal 114 are both assumed to be access points. In FIG. 1 , the wireless terminal 113 and the wireless terminal 114 are depicted as being located away from the in-vehicle network 20, but in reality, the wireless terminal 113 and the wireless terminal 114 are configured to be included in the in-vehicle network 20.

[0018] Wireless terminals 111 and 113 are connected to a wireless network 301, and wireless communication is possible between wireless terminals 111 and 113. Wireless terminals 112 and 114 are connected to a wireless network 302, and wireless communication is possible between wireless terminals 112 and 114. Wireless networks 301 and 302 may be provided by the same mobile communications carrier or by different mobile communications carriers.

[0019] 1 has a configuration in which the gateway, wireless terminal, and wireless network are all duplicated. Therefore, in the conventional communication relay system 10, data communication is not interrupted even if a failure occurs at any point.

[0020] However, in the configuration of the conventional communication relay system 10 shown in Fig. 1, the same signal is transmitted from each gateway to multiple wireless networks (wireless network 301 and wireless network 302). In other words, the same signal is transmitted twice to one wireless network from different gateways. Therefore, compared to a configuration in which each device is not duplicated, twice as many signals are transmitted to one wireless network. As a result, the communication bands of the wireless networks 301 and 302 are constricted, and communication costs are also increased.

[0021] [One embodiment] <Configuration example of a communication relay system according to this embodiment> Next, a configuration example of a communication relay system 100 according to one embodiment of the present invention will be described. Fig. 2 is a block diagram showing a configuration example of a duplexed communication relay system 100 according to one embodiment. In the communication relay system 100, a general wireless network is also configured in a duplexed manner.

[0022] The communication relay system 100 has a function of relaying data transmitted and received between the in-vehicle network 20 and the base station network 30 via wireless networks 301 and 302. In the communication relay system 100, networks and devices that are common to those in Fig. 1 are assigned the same reference numerals. The communication relay system 100 includes duplicated communication relay devices. In the communication relay system 100, all communication networks except for the wireless network 301 (an example of a first wireless network) and the wireless network 302 (an example of a second wireless network) are wired.

[0023] The communication relay system 100 includes a communication relay device 121 and a communication relay device 122 (both of which are examples of a first communication relay device) between the gateway 101, the gateway 102, and the wireless terminal 111 and the wireless terminal 112. A network from an in-vehicle network 20 (an example of a first network) to the wireless terminals 111 and 112 is configured on the vehicle side. Therefore, the communication relay device 121 and the communication relay device 122 are installed in the vehicle. The vehicle network according to this embodiment includes the communication relay device 121 and the communication relay device 122 in addition to the conventional in-vehicle network 20. The communication relay devices 121 and 122 are set as either an active system or a standby system that relays data between the in-vehicle network 20 and the wireless network 301 and the wireless network 302.

[0024] The communication relay device 121 is connected to the gateways 101 and 102 and the wireless terminals 111 and 112. Specifically, the communication relay device 121 is connected to the gateway 101 by a communication line 201 and to the gateway 102 by a communication line 203. The communication relay device 121 is also connected to the wireless terminal 111 by a communication line 211 and to the wireless terminal 112 by a communication line 212. As described above, the communication lines 211 and 212 are wired lines.

[0025] The communication relay device 122 is connected to the gateways 101 and 102 and the wireless terminals 111 and 112. Specifically, the communication relay device 122 is connected to the gateway 101 by a communication line 202 and to the gateway 102 by a communication line 204. The communication relay device 122 is also connected to the wireless terminal 111 by a communication line 213 and to the wireless terminal 112 by a communication line 214.

[0026] The communication relay device 121 and the communication relay device 122 are connected by a duplexed communication line 215 (an example of a first communication line) so that they can communicate signals with each other. The communication relay devices 121 and 122 monitor the status of their own system and the other system via the mutually connected communication line 215 and share each other's settings and status. By duplexing the communication line 215, even if one communication line 215 malfunctions, communication can continue via the other communication line 215. The communication line 215 is used, for example, by the communication relay device 121 and the communication relay device 122 to transmit heartbeat signals and status signals to each other. For this reason, it is desirable that the communication line 215 be a wired line.

[0027] The communication relay device 121 and the communication relay device 122 share information indicating whether they are set as an active system or a standby system. The communication relay device 121 and the communication relay device 122 also share information indicating that a failure has occurred in the communication line 215 or in either the communication relay device 121 or 122.

[0028] When the communication relay device 122 detects that a failure has occurred in the communication relay device 121, it transitions from a standby system to an active system. Then, the communication relay device 122 takes over the process of duplicating and transmitting data to the wireless networks 301 and 302. When the communication relay device 121 detects that a failure has occurred, it transitions from an active system to a standby system, and remains in the standby system even after the failure is recovered.

[0029] The wireless terminal 111 is connected to the wireless terminal 113 via the wireless network 301. The wireless terminal 112 is connected to the wireless terminal 114 via the wireless network 302.

[0030] The communication relay system 100 includes a communication relay device 123 and a communication relay device 124 (both of which are examples of second communication relay devices) between the gateway 103, the gateway 104, and the wireless terminal 113 and the wireless terminal 114. The base station network 30 (an example of a second network) to the wireless terminals 113 and 114 is configured on the ground side. For this reason, the communication relay device 123 and the communication relay device 124 are installed in a control station on the ground side.

[0031] The ground network according to this embodiment includes a communication relay device 123 and a communication relay device 124 in addition to the conventional base station network 30. The communication relay devices 123 and 124 are set as either an active system or a standby system that relays data between the base station network 30 and the wireless networks 301 and 302 to the base station network 30.

[0032] The communication relay device 123 is connected to the gateways 103 and 104 and the wireless terminals 113 and 114. Specifically, the communication relay device 123 is connected to the gateway 103 by a communication line 231 and to the gateway 104 by a communication line 232. The communication relay device 123 is also connected to the wireless terminal 113 by a communication line 221 and to the wireless terminal 114 by a communication line 223. As described above, the communication lines 221 and 223 are wired lines.

[0033] The communication relay device 124 is connected to the gateways 103 and 104 and the wireless terminals 113 and 114. Specifically, the communication relay device 124 is connected to the gateway 103 by a communication line 233 and to the gateway 104 by a communication line 234. The communication relay device 124 is also connected to the wireless terminal 113 by a communication line 222 and to the wireless terminal 114 by a communication line 224. As described above, the communication lines 222 and 224 are wired lines.

[0034] The communication relay devices 123 and 124 are connected by a duplexed communication line 225 (an example of a second communication line) so that they can communicate signals with each other. The communication relay devices 123 and 124 monitor the status of their own system and the other system via the mutually connected communication line 225 and share each other's settings and status. By duplexing the communication line 225, the communication relay devices 123 and 124 can continue communication via the other communication line 225 even if one communication line 225 malfunctions. The communication line 225 is used, for example, by the communication relay devices 123 and 124 to transmit heartbeat signals and status signals to each other. For this reason, it is desirable that the communication line 225 be a wired line.

[0035] The communication relay device 123 and the communication relay device 124 share information indicating whether they are set as an active system or a standby system. The communication relay device 123 and the communication relay device 124 also share information indicating that a failure has occurred in the communication line 225 or that a failure has occurred in either the communication relay device 123 or 124. When the communication relay device 124 detects that a failure has occurred in the communication relay device 123, it transitions from a standby system to an active system. The communication relay device 124 then takes over the process of transmitting duplicated data to the wireless networks 301 and 302. When a failure has been detected in the communication relay device 123, it transitions from an active system to a standby system, and remains in the standby system even after the failure is recovered.

[0036] Each communication relay device (communication relay devices 121 to 124) can transition between an active state (active) and a standby state (idle state). For example, when communication relay device 121 in a vehicle network is the active state, communication relay device 122 is the standby state. In this way, when one communication relay device is the active state, the other communication relay device is the standby state.

[0037] The communication relay devices 121 and 122 communicate periodically via a communication line 215, and the settings and status of the communication relay devices 121 and 122 are always shared. Similarly, the communication relay devices 123 and 124 communicate periodically via a communication line 225, and the settings and system status of the communication relay devices 123 and 124 are always shared.

[0038] If communication on the communication line 215 or the communication line 225 is interrupted, the standby communication relay device determines that a failure has occurred in the active communication relay device and quickly transitions to the active system. In this case, the active communication relay device does not transition to the standby system. Therefore, it is possible for both communication relay devices to become the active system.

[0039] Furthermore, transmission to wireless networks 301 and 302 is performed only from the communication relay device of the active system. Even if the communication relay device of the standby system receives a signal from the gateway, it does not transmit the signal to wireless networks 301 and 302. Note that when the communication relay device of the standby system receives a signal from wireless networks 301 and 302, it may transmit the signal to the gateway connected to that communication relay device.

[0040] <Example of internal configuration of communication relay device> Here, an example of the internal configuration of the communication relay device will be described. Fig. 3 is a block diagram showing an example of the internal configuration of the communication relay device 121. Note that the communication relay devices 122 to 124 have the same internal configuration as the communication relay device 121, so an explanation of the example of the internal configuration of the communication relay devices 122 to 124 will be omitted.

[0041] The communication relay device 121 relays data transmitted and received between the in-vehicle network 20 and the base station network 30 via the wireless networks 301 and 302. The communication relay device 121 includes a relay communication unit 11, a data processing unit 12, a buffer unit 13, a state storage unit 14, an other-system monitoring unit 15, and an other-system communication unit 16.

[0042] When the active system is set, the relay communication unit 11 relays data to the wireless networks 301 and 302, and when the standby system is set, the relay communication unit 11 does not relay data received from the in-vehicle network 20 to the wireless networks 301 and 302. For example, the relay communication unit 11 passes data received from the gateways 101 and 102 on the in-vehicle network 20 side via the communication lines 201 and 203 to the data processing unit 12. Then, the relay communication unit 11 transmits the data, to which a destination has been assigned by the data processing unit 12, to the wireless terminal 111 via the communication line 211. Similarly, the relay communication unit 11 transmits the data, to which a destination has been assigned by the data processing unit 12, to the wireless terminal 112 via the communication line 212.

[0043] Conversely, relay communication unit 11 passes data received from wireless terminals 111 and 112 via communication lines 211 and 212 to data processing unit 12. Then, relay communication unit 11 transmits the data, to which a destination has been assigned by data processing unit 12, to gateway 101 via communication line 201. Similarly, relay communication unit 11 transmits the data, to which a destination has been assigned by data processing unit 12, to gateway 102 via communication line 203.

[0044] The data processing unit 12 adds destination data to the data received by the relay communication unit 11. Note that the data processing unit 12 may also delete communication path information from the data that the wireless terminals 111 and 112 receive from the wireless networks 301 and 302 and transfer to the communication relay device 121.

[0045] When the communication relay device 121 is in the standby system, the buffer unit 13 stores for a certain period the data received by the relay communication unit 11 and processed by the data processing unit 12. The standby communication relay device 121 does not transmit data to the wireless networks 301 and 302, but transitions to the active system when communication on the communication line 215 is cut off.

[0046] After transitioning to the active system, the communication relay device 121 transmits the data acquired from the buffer unit 13 to the wireless networks 301 and 302, and then continues to transmit data received from the gateways 101 and 102 to the wireless networks 301 and 302. This operation enables the communication relay device 121 to transmit data to the wireless networks 301 and 302 without losing any data.

[0047] The state storage unit 14 stores the state of either the active system or the standby system set in the communication relay device 121 itself. If the active system is stored in the state storage unit 14, the communication relay device 121 operates as the active system. On the other hand, if the standby system is stored in the state storage unit 14, the communication relay device 121 operates as the standby system. The data processing unit 12 references the state storage unit 14, and if the communication relay device 121 is the active system, it passes the processed data to the relay communication unit 11, which transmits the data to the wireless terminals 111 and 112. On the other hand, the data processing unit 12 references the state storage unit 14, and if the communication relay device 121 is the standby system, it stores the processed data in the buffer unit 13.

[0048] The other system monitoring unit 15 writes the settings and status of the communication relay device 122 acquired by the other system communication unit 16 into the status storage unit 14 and monitors the communication relay device 122. For example, the other system monitoring unit 15 monitors for communication disruption on the communication line 215. If the other system monitoring unit 15 determines that communication on the communication line 215 has not been disrupted, it does not rewrite the status storage unit 14. However, if the other system monitoring unit 15 determines that communication on the communication line 215 has been disrupted and the standby system is stored in the status storage unit 14, it rewrites the status storage unit 14 to the active system.

[0049] The other-system communication unit 16 is connected to a communication relay device 122 (an example of another communication relay device) via a communication line 215, and communicates with the communication relay device 122 via the communication line 215. For example, the other-system communication unit 16 transmits a heartbeat signal to the communication relay device 122, which is another system, and receives a heartbeat signal from the communication relay device 122. The other-system communication unit 16 also transmits a signal indicating the state of its own system (active system or standby system) to the communication relay device 122. Then, the other-system communication unit 16 transmits a signal indicating the state (standby system or active system) from the communication relay device 122 to the in-vehicle network 20.

[0050] <Example of Computer Hardware Configuration> Next, the hardware configuration of the computer 60 constituting the communication relay device 121 will be described. FIG. 4 is a block diagram showing an example of the hardware configuration of the computer 60. The computer 60 is an example of hardware used as a computer capable of operating as the communication relay device 121 according to this embodiment. Note that the communication relay devices 122 to 124 have the same hardware configuration as the communication relay device 121, and therefore a description of the example hardware configuration of the communication relay devices 122 to 124 will be omitted. In the communication relay system 100 and the communication relay device 121 according to this embodiment, each functional block is configured by the computer 60 (computer) executing a program, and the functional blocks work together to realize the communication relay method described below in FIGS. 6, 8, and 9.

[0051] The computer 60 includes a CPU (Central Processing Unit) 61, a ROM (Read Only Memory) 62, and a RAM (Random Access Memory) 63, each connected to a bus 64. The computer 60 further includes a non-volatile storage 65 and a network interface 66.

[0052] The CPU 61 reads out the program code of the software that realizes each function according to this embodiment from the ROM 62, loads it into the RAM 63, and executes it. Variables, parameters, etc. that are generated during the calculation processing of the CPU 61 are temporarily written to the RAM 63, and these variables, parameters, etc. are read out by the CPU 61 as appropriate.

[0053] The nonvolatile storage 65 may be, for example, a hard disk drive (HDD), a solid state drive (SSD), or a nonvolatile memory. In addition to an operating system (OS) and various parameters, programs for operating the computer 60 are recorded in the nonvolatile storage 65. The ROM 62 and the nonvolatile storage 65 record programs, data, and the like required for the CPU 61 to operate. In other words, the ROM 62 and the nonvolatile storage 65 are used as examples of computer-readable, non-transitory storage media that store programs executed by the computer 60.

[0054] For example, a network interface card (NIC) or the like is used as the network interface 66. The network interface 66 transmits and receives various data between devices via a local area network (LAN), a dedicated line, or the like connected to a terminal of the NIC.

[0055] <Data flow during normal operation> Fig. 5 is a block diagram showing an example of data flow during normal operation. Communication relay devices 121 and 123 are active systems, and communication relay devices 122 and 124 are standby systems. Fig. 5 shows only the lines over which data is communicated, and does not show the lines over which data is not transmitted.

[0056] Here, an uplink case will be described in which data is transmitted from the in-vehicle network 20 to the base station network 30. The gateway 101 transmits data to the communication relay device 121 via a communication line 201, and transmits the same data to the communication relay device 122 via a communication line 202. The gateway 102 transmits data to the communication relay device 121 via a communication line 203, and transmits the same data to the communication relay device 122 via a communication line 204.

[0057] For example, since the in-vehicle network 20 of a railway or the like is configured for redundancy, the communication relay devices 121 and 122 receive the same data in duplicate. The data received by the communication relay devices 121 and 122 from the in-vehicle network 20 is not discarded. The communication relay device 121 of the execution system relays data to the base station network 30 via the wireless networks 301 and 302.

[0058] That is, the communication relay device 121, which is the execution system, relays data received from the in-vehicle network 20 to the wireless networks 301 and 302. The communication relay device 121 also relays data received from the base station network 30 via the wireless networks 301 and 302 to the in-vehicle network 20.

[0059] For example, the communication relay device 121 transmits data to the wireless terminal 111 via the communication line 211, and transmits the same data to the wireless terminal 112 via the communication line 212. The communication relay device 122, which is a standby system, does not relay data received from the in-vehicle network 20 to the wireless networks 301 and 302. In addition, the communication relay device 122 does not relay data received from the base station network 30 via the wireless networks 301 and 302 to the in-vehicle network 20. Therefore, the communication relay device 122 does not transmit data to the wireless terminals 111 and 112.

[0060] Wireless terminal 111 transmits data to wireless terminal 113 via wireless network 301. Wireless terminal 112 transmits data to wireless terminal 114 via wireless network 302. Wireless terminal 113 transmits data to communication relay device 123 via communication line 221, and also transmits the same data to communication relay device 124 via communication line 222. Wireless terminal 114 transmits data to communication relay device 123 via communication line 223, and also transmits the same data to communication relay device 124 via communication line 224.

[0061] The communication relay device 123, which is the execution system, relays data received from the wireless networks 301 and 302 to the base station network 30. The communication relay device 123 also relays data received from the base station network 30 to the wireless networks 301 and 302. For example, the communication relay device 123 transmits data to the gateway 103 via the communication line 231, and transmits the same data to the gateway 104 via the communication line 232.

[0062] The communication relay device 124 of the standby system does not relay data received from the wireless network 301 and the wireless network 302 to the base station network 30. Furthermore, the communication relay device 124 does not relay data received from the base station network 30 to the wireless network 301 and the wireless network 302. For example, the communication relay device 124 does not transmit data to the gateways 103 and 104. The communication relay device 124 of the standby system may buffer data for a predetermined period of time. By buffering the data, the communication relay device 124 transitions to the active system and transmits data to the base station network 30 when an abnormality occurs in the communication relay device 123 of the active system.

[0063] <Sequence Diagram During Normal Operation> Figure 6 is a sequence diagram showing an example of the operation of each device in the communication relay system 100 during normal operation. In Figure 6, communication relay devices 121 and 123 are active systems, and communication relay devices 122 and 124 are standby systems. The communication relay devices 121 and 122 communicate with each other (S1) and monitor each other's status. Similarly, the communication relay devices 123 and 124 also communicate with each other (S2) and monitor each other's status.

[0064] First, we will explain the flow of data transmitted from the gateway 101 and an example of the operation of each device. The gateway 101 transmits data to the communication relay device 121 (S11), and then transmits the same data to the communication relay device 122 (S12). The communication relay device 122 is a standby device, so it does not transmit data to the wireless terminals 111 and 112.

[0065] On the other hand, since the communication relay device 121 is an execution system, it duplicates the data and transmits it to the wireless network 301 and the wireless network 302. For example, the communication relay device 121 transmits the data received from the gateway 101 to the wireless terminal 111 (S13), and also transmits the same data to the wireless terminal 112 (S14).

[0066] The wireless terminal 112 transmits data to the wireless terminal 114 via the wireless network 302 (S15). The wireless terminal 114 transmits the data received via the wireless network 302 to the communication relay device 124 (S16) and also to the communication relay device 123 (S17). The communication relay device 124 is in standby mode and has therefore stopped transmitting data.

[0067] Because the communication relay device 123 is an execution system, when it receives duplicated data from the wireless networks 301 and 302, it relays the first-arrived data to the base station network 30. However, the communication relay device 123 does not relay the later-arrived data to the base station network 30. For example, the communication relay device 123 transmits data received from the wireless terminal 114 to the gateway 103 (S18), and then transmits the same data to the gateway 104 (S19).

[0068] In step S13, wireless terminal 111 receives data from communication relay device 121 and transmits the data to wireless terminal 113 via wireless network 301 (S20). Wireless terminal 113 transmits the received data to communication relay device 124 (S21) and also transmits the same data to communication relay device 123 (S22). Communication relay device 124 is in the standby mode and has stopped transmitting data. Communication relay device 123 is in the active mode, but has already transmitted data in steps S18 and S19. Therefore, communication relay device 123 stops transmitting the same data due to its first-come, first-served function.

[0069] Next, an example of the flow of data transmitted from the gateway 102 and the operation of each device will be described. The gateway 102 transmits data to the communication relay device 121 (S31), and transmits the same data to the communication relay device 122 (S32). The communication relay device 122 is a standby device, and therefore does not transmit data to the wireless terminals 111 and 112. On the other hand, the communication relay device 121 is an active device, and therefore transmits the data received from the gateway 102 to the wireless terminal 111 (S33), and also transmits the same data to the wireless terminal 112 (S34).

[0070] The data flow and operation example of each device in the following steps S35 to S42 are the same as the data flow and operation example of each device in steps S15 to S22, so a duplicated explanation will be omitted.

[0071] Note that, although data may not be transmitted to the gateway 104, there are specifications that suffice as long as data is transmitted to the gateway 103. Therefore, depending on the specifications of the communication relay devices 123 and 124, the processes of steps S19, S21, and S22 in FIG.

[0072] <Data Flow When a Failure Occurs> Next, a description will be given of the data flow when a failure occurs in the communication relay device 121, which is the execution system. Fig. 7 is a sequence diagram showing an example of the operation of each device in the communication relay system when a failure occurs in the communication relay device 121.

[0073] If a failure occurs in the communication relay device 121, it is not possible to know whether the communication relay device 121 is correctly transmitting data to the wireless terminals 111 and 112. For this reason, the communication lines 211 and 212 are shown by dashed lines in FIG.

[0074] When the communication relay device 122, which acquires the status of the communication relay device 121 from the communication line 215, detects a failure in the communication relay device 121, it immediately transitions from the standby system to the active system regardless of whether the communication relay device 121 is in the active system or standby system state. Thereafter, the communication relay device 122 transmits data to the wireless terminal 111 via the communication line 213, and transmits the same data to the wireless terminal 112 via the communication line 214. Therefore, the communication relay device 122 can maintain the continuity of data transmitted from the vehicle network to the ground network.

[0075] The wireless terminal 111 transmits data to the wireless terminal 113 via the wireless network 301. The wireless terminal 112 transmits data to the wireless terminal 114 via the wireless network 302. The subsequent data flow is as described in FIG.

[0076] When the communication relay device 121 recovers from the failure, either the communication relay device 121 or the communication relay device 122 becomes the active system, depending on the initial setting value and the severity of the failure. The communication relay device that has transitioned to the standby system does not transmit data to the wireless network 301 or the wireless network 302. Therefore, the wireless relay device that has transitioned to the standby system stops transmitting data to the wireless terminal. For example, it is better for a communication relay device that fails frequently to remain in the standby system even after recovering from the failure. For this reason, a communication relay device that fails frequently is initially set to remain in the standby system even after recovery from the failure.

[0077] Furthermore, if the level of the failure is at the level of a warning, the communication relay device 121 can be returned to the active system after recovering from the failure without any problems. However, if the level of the failure is an error worse than a warning or a device malfunction, the communication relay device 121 will not operate normally even if it is returned to the active system after recovering from the failure. For this reason, the communication relay device 121 changes its transition from the active system to the standby system when recovering from the failure depending on the level of the failure.

[0078] <Sequence Diagram When a Fault Occurs> Figure 8 is a sequence diagram showing an example of the operation of each device in the communication relay system 100 when a fault occurs in the communication relay device 121, which is the active system. When a fault occurs in the communication relay device 121, communication between the communication relay devices 121 and 122 is interrupted (S51). As a result, the communication relay device 122 transitions from the standby system to the active system. Meanwhile, the communication relay devices 123 and 124 can communicate with each other (S52) and monitor each other's status.

[0079] First, we will explain the flow of data sent from the gateway 101 and an example of the operation of each device. The gateway 101 sends data to the communication relay device 121 (S61), and then sends the same data to the communication relay device 122 (S62). Because a failure has occurred in the communication relay device 121, unlike the data flow in Figure 6, data transmission processing originating from the communication relay device 121 is not performed or communication is undefined.

[0080] Since the communication relay device 122 has transitioned to the active system, it transmits the data received from the gateway 101 to the wireless terminal 111 (S63), and also transmits the same data to the wireless terminal 112 (S64).

[0081] The data flow and operation example of each device in the subsequent steps S65 to S72 are the same as the data flow and operation example of each device in steps S15 to S22 in FIG. 6, so a duplicated description will be omitted.

[0082] Next, an example of the flow of data transmitted from the gateway 102 and the operation of each device will be described. The gateway 102 transmits data to the communication relay device 121 (S81), and then transmits the same data to the communication relay device 122 (S82). Because a failure has occurred in the communication relay device 121, unlike the data flow in Figure 6, data transmission processing originating from the communication relay device 121 is not performed or communication becomes undefined.

[0083] Since the communication relay device 122 has transitioned to the active system, it transmits the data received from the gateway 101 to the wireless terminal 111 (S83), and also transmits the same data to the wireless terminal 112 (S84).

[0084] The data flow and operation example of each device in the subsequent steps S85 to S92 are the same as the data flow and operation example of each device in steps S15 to S22, so a duplicated explanation will be omitted.

[0085] <Sequence Diagram for Failure Recovery> Figure 9 is a sequence diagram showing an example of the operation of each device in the communication relay system 100 when the communication relay device 121 recovers from a failure. As described above, the communication relay device 121 in which the failure occurred does not transition to the active system even after the failure is recovered, but remains in the standby system. However, since the communication relay device 121 has recovered from the failure, it is able to communicate with the communication relay device 122 (S101) and monitors each other's status. In addition, the communication relay devices 123 and 124 are also able to communicate with each other (S102) and monitor each other's status.

[0086] First, we will explain the flow of data transmitted from the gateway 101 and an example of the operation of each device. The gateway 101 transmits data to the communication relay device 121 (S111), and transmits the same data to the communication relay device 122 (S112). The communication relay device 121 is a standby device, so it does not transmit data to the wireless terminals 111 and 112.

[0087] On the other hand, since the communication relay device 122 is the execution system, it transmits the data received from the gateway 101 to the wireless terminal 111 (S113), and also transmits the same data to the wireless terminal 112 (S114). The data flow and operation example of each device in the following steps S115 to S122 are the same as the data flow and operation example of each device in steps S15 to S22 in Fig. 6, so duplicated explanations will be omitted.

[0088] Next, an example of the flow of data transmitted from the gateway 102 and the operation of each device will be described. The gateway 102 transmits data to the communication relay device 121 (S131), and transmits the same data to the communication relay device 122 (S132). The communication relay device 121 is a standby device, and therefore does not transmit data to the wireless terminals 111 and 112.

[0089] On the other hand, the communication relay device 122, which is the active system, transmits the data received from the gateway 101 to the wireless terminal 111 (S133), and also transmits the same data to the wireless terminal 112 (S134).

[0090] The data flow and operation example of each device in the subsequent steps S135 to S142 are the same as the data flow and operation example of each device in steps S15 to S22 in FIG. 6, so a duplicated description will be omitted.

[0091] So far, we have explained the flow of signals transmitted from the vehicle network to the ground network (in the case of uplink). Note that the flow of signals transmitted from the ground network to the vehicle network (in the case of downlink) also operates in the opposite manner to the signal flow in the case of uplink, with the communication relay devices 121 to 124. Here, we will omit detailed descriptions of the signal flow in the case of downlink and the operation of each device using sequence diagrams.

[0092] In the communication relay system 100 according to the embodiment described above, one of the two communication relay devices in the in-vehicle network 20 on the data transmission side is an active system and the other is a standby system. The active system communication relay device transmits data to the wireless network, but the standby system communication relay device does not transmit data to the wireless network. Therefore, there is no data transmitted from the standby system communication relay device to the wireless network, and the communication bandwidth for data transmitted to the wireless network can be reduced. Since public network lines of mobile communication carriers often use a pay-as-you-go system, the communication relay system 100 according to the embodiment has the effect of reducing communication costs.

[0093] Furthermore, in the communication relay system 100 according to this embodiment, the two communication relay devices monitor each other's operation, and if a failure occurs in the active communication relay device and communication is interrupted, the standby communication relay device immediately switches to the active system. The active communication relay device then transmits data to the wireless network, shortening communication dead time and preventing data loss. This also ensures that data arrives reliably at the gateway at the end of the wireless network.

[0094] Furthermore, since the communication relay device that has recovered from the failure continues to operate as a standby system, it does not transmit unnecessary data to the wireless network. As a result, the communication bandwidth of the wireless network is not constrained by data. Also, two communication relay devices are installed on the data receiving side, and the two communication relay devices monitor each other's operation. Data received from the wireless network by the wireless terminal on the data receiving side is sent to the communication relay device on the data receiving side, and the data is forwarded from this communication relay device to the gateway on the data receiving side.

[0095] Here, the communication relay device on the data receiving side gives priority to transmitting data received first from a wireless terminal to the gateway, and does not transmit data received thereafter from another wireless terminal to the gateway. As a result, the gateway on the data receiving side does not receive the same data twice, and does not need to perform processes such as duplicate determination and data discarding regarding data reception.

[0096] The present invention is not limited to the above-described embodiments, and various other applications and modifications are possible without departing from the spirit of the present invention as defined in the claims. For example, the above-described embodiments provide detailed and specific descriptions of the system configuration in order to clearly explain the present invention, and are not necessarily limited to systems that include all of the described configurations. Furthermore, it is also possible to add, delete, or replace part of the configuration of the present embodiments with other configurations. Furthermore, the control lines and information lines shown are those considered necessary for explanation, and do not necessarily represent all control lines and information lines in the product. In reality, it can be assumed that almost all configurations are interconnected.

[0097] 11... relay communication unit, 12... data processing unit, 13... buffer unit, 14... status storage unit, 15... other system monitoring unit, 16... other system communication unit, 20... in-vehicle network, 30... base station network, 100... communication relay system, 101-104... gateways, 111-114... wireless terminals, 121-124... communication relay devices, 201-204, 211-215, 221-225, 231-234... communication lines, 301, 302... wireless network

Claims

1. A communication relay system that relays data transmitted and received between a first network and a second network via a first wireless network and a second wireless network, comprising: two first communication relay devices configured as either an active system or a standby system that relay the data between the first network, and the first wireless network and the second wireless network; and two second communication relay devices configured as either an active system or a standby system that relay the data between the second network, and the first wireless network and the second wireless network to the second network, wherein the first communication relay device of the active system relays the data received from the first network to the first wireless network and the second wireless network, the first communication relay device of the standby system does not relay the data received from the first network to the first wireless network and the second wireless network, the second communication relay device of the active system relays the data received from the first wireless network and the second wireless network to the second network, and the second communication relay device of the standby system does not relay the data received from the first wireless network and the second wireless network to the second network.

2. The communication relay system described in claim 1, wherein the first communication relay device of the execution system duplicates the data and transmits it to the first wireless network and the second wireless network, and the second communication relay device of the execution system receives the duplicated data from the first wireless network and the second wireless network, relays the first-arriving data to the second network, and does not relay the later-arriving data to the second network.

3. The communication relay system described in claim 2, wherein the two first communication relay devices monitor the status of their own system and the other system via a first communication line connected to each other and share each other's settings and status, and the two second communication relay devices monitor the status of their own system and the other system via a second communication line connected to each other and share each other's settings and status.

4. The communication relay system described in claim 3, wherein when the first communication relay device of the standby system detects that a failure has occurred in the first communication relay device of the active system, it transitions from the standby system to the active system and takes over the process of duplicating and transmitting the data to the first wireless network and the second wireless network.

5. The communication relay system according to claim 4, wherein the first communication relay device, upon detection of a fault, transitions from an active system to a standby system, and remains in the standby system even after the fault is recovered from.

6. The communication relay system described in claim 4, wherein the first communication relay device, upon detection of a fault, transitions from an active system to a standby system, and after the fault is recovered, one of the first communication relay devices becomes the active system depending on the initial settings and the severity of the fault, and the first communication relay device that has transitioned to the standby system does not transmit the data to the first wireless network or the second wireless network.

7. A communication relay system as described in claim 4, wherein the setting is information indicating whether an active system or a standby system is set, and the state is information indicating that a fault has occurred in the first communication line or the second communication line, or that a fault has occurred in the first communication relay device or the second communication relay device.

8. The communication relay system described in claim 4, wherein the first communication relay device of the active system relays data received from the second network via the first wireless network and the second wireless network to the first network, the first communication relay device of the standby system does not relay data received from the second network via the first wireless network and the second wireless network to the first network, the second communication relay device of the active system relays the data received from the second network to the first wireless network and the second wireless network, and the second communication relay device of the standby system does not relay the data received from the second network to the first wireless network and the second wireless network.

9. A communication relay device that relays data transmitted and received between a first network and a second network via a first wireless network and a second wireless network, comprising: a state memory unit that stores a state in which either an active system or a standby system is set; and a relay communication unit that relays the data to the first wireless network and the second wireless network when the active system is set, and does not relay the data received from the first network to the first wireless network and the second wireless network when the standby system is set.

10. A communication relay device as described in claim 9, comprising: an other system communication unit connected to another communication relay device by a communication line and communicating with the other communication relay device via the communication line; and an other system monitoring unit that writes the settings and status of the other communication relay device acquired by the other system communication unit into the status memory unit and monitors the other communication relay device.

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