Communication device and communication program

Abstract

A communication device (2) is provided with a transfer control unit (31), a communication accelerator (16), a switching condition determination unit (32), and a path switching unit (33). The transfer control unit is configured to change a transfer method for transferring communication data in accordance with the communication state of a first communication unit (14). The communication accelerator includes hardware capable of executing a process of transferring the communication data from a second communication unit (12) to the first communication unit faster than the transfer control unit. The switching condition determination unit determines whether a path switching condition is satisfied. When the path switching condition is satisfied, the path switching unit switches the transfer path of the communication data by executing the process of transferring the communication data by using the transfer control unit without passing through the communication accelerator.

Description

Communication device and communication program CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This international application claims the benefit of Japanese Patent Application No. 2024-071434, filed with the Japan Patent Office on April 25, 2024, the entire disclosure of which is incorporated herein by reference.

[0002] The present disclosure relates to a communication device and a communication program for performing data communication.

[0003] Patent document 1 describes that a user's wireless terminal is equipped with an accelerator that speeds up communication with a server, and when the user's wireless terminal receives signaling from the user that includes an instruction to speed up communication, data is transmitted via the accelerator.

[0004] U.S. Patent No. 9,769,239

[0005] As a result of detailed investigation by the inventors, it was found that if an accelerator is used to speed up communication only when a user instructs it to do so, the accelerator cannot be optimally utilized in response to environmental changes that the user cannot immediately know, and data communication speeds may not be sufficiently increased, or adverse effects may occur due to the increased speed of data communication.

[0006] The present disclosure achieves both the transfer processing required in abnormal situations and high-speed data communication in normal times.

[0007] One aspect of the present disclosure is a communication device including a transfer control unit, a communication accelerator, a switching condition determination unit, and a path switching unit.

[0008] The transfer control unit is configured to be able to change the transfer method for transferring input communication data in accordance with the communication state of the first communication unit configured to perform data communication.

[0009] The communication accelerator includes hardware configured to perform data communication and capable of executing the process of transferring communication data from a second communication unit, which is different from the first communication unit, to the first communication unit faster than the transfer control unit.

[0010] The switching condition determination unit is configured to determine whether a preset path switching condition indicating that transfer of communication data to the first communication unit needs to be suppressed is established.

[0011] The path switching unit is configured to switch the transfer path of the communication data by executing the process of transferring the communication data using the transfer control unit without going through the communication accelerator when the path switching condition is met.

[0012] The communication device of the present disclosure configured in this manner executes the process of transferring communication data via the communication accelerator during normal times when the path switching condition is not satisfied, and can execute the process of transferring communication data using the transfer control unit during abnormal times when the path switching condition is satisfied. Therefore, the communication device of the present disclosure can effectively utilize the communication accelerator, which can execute the process of transferring communication data faster than the transfer control unit, to speed up communication during normal times, while making it possible to apply processes that are not supported by the communication accelerator using the transfer control unit during abnormal times when the path switching condition is satisfied, and can thereby achieve both the transfer process required during abnormal times and the high-speed data communication during normal times.

[0013] Another aspect of the present disclosure is a communication program for causing a computer of a communication device including a transfer control unit and a communication accelerator to function as a switching condition determination unit and a path switching unit.

[0014] A computer controlled by the communication program of the present disclosure can constitute part of the communication device of the present disclosure, and can obtain the same effects as the communication device of the present disclosure.

[0015] FIG. 1 is a block diagram showing the configuration of a communication system of a first embodiment. FIG. 2 is a diagram showing a transfer route when a route switching condition is not met in the first embodiment. FIG. 3 is a diagram showing a transfer route when a route switching condition is met in the first embodiment. FIG. 4 is a diagram showing a transfer route when a route switching condition is not met in the second embodiment. FIG. 5 is a diagram showing a transfer route when a route switching condition is met in the second embodiment. FIG. 6 is a block diagram showing the configuration of a communication system of a third embodiment. FIG. 7 is a diagram showing a transfer route when a route switching condition is not met in the third embodiment. FIG. 8 is a diagram showing a transfer route when a route switching condition is met in the third embodiment.

[0016] First Embodiment A first embodiment of the present disclosure will be described below with reference to the drawings.

[0017] 1, the communication system 1 of this embodiment is mounted on a vehicle and includes a communication device 2, a plurality of ECUs 3, 4, and 5, and a network switch 6. ECU is an abbreviation for Electronic Control Unit.

[0018] The ECU 3 executes processes for implementing various AD functions, for example. AD stands for Autonomous Driving. The ECU 4 executes processes for implementing various ADAS functions, for example. ADAS stands for Advanced Driver Assistance System. The ECU 5 executes processes for controlling the display of meters and navigation systems, for example.

[0019] The network switch 6 has a plurality of ports and relays communication frames between the ports. In this embodiment, the network switch 6 is an L3 switch or an L4 switch.

[0020] A first wired communication unit 12 (to be described later), a second wired communication unit 13 (to be described later), and ECUs 3, 4, and 5 are connected to a plurality of ports of the network switch 6.

[0021] The communication device 2 includes a control unit 11 , a first wired communication unit 12 , a second wired communication unit 13 , a first wireless communication unit 14 , a second wireless communication unit 15 , and a communication accelerator 16 .

[0022] The control unit 11 is an electronic control device mainly composed of a microcomputer including a CPU 21, a ROM 22, a RAM 23, etc. The various functions of the microcomputer are realized by the CPU 21 executing a program stored in a non-transitory tangible recording medium. In this example, the ROM 22 corresponds to the non-transitory tangible recording medium storing the program. Furthermore, the execution of this program results in the execution of a method corresponding to the program. Note that some or all of the functions executed by the CPU 21 may be configured as hardware using one or more ICs, etc. Furthermore, the number of microcomputers constituting the control unit 11 may be one or more.

[0023] The first wired communication unit 12 performs wired data communication between the communication device 2 and the ECUs 3, 4, and 5. In this embodiment, the first wired communication unit 12 performs data communication in accordance with, for example, the Ethernet standard. Ethernet is a registered trademark.

[0024] The second wired communication unit 13 performs wired data communication between the communication device 2 and the ECUs 3, 4, and 5. In this embodiment, the second wired communication unit 13 performs data communication in accordance with, for example, the Ethernet standard.

[0025] The first wireless communication unit 14 performs wireless data communication between the communication device 2 and a cloud server 100 installed outside the vehicle. In this embodiment, the first wireless communication unit 14 performs, for example, cellular communication.

[0026] The second wireless communication unit 15 performs wireless data communication between the communication device 2 and the cloud server 100. In this embodiment, the second wireless communication unit 15 performs, for example, Wi-Fi communication. Wi-Fi is a registered trademark.

[0027] The communication accelerator 16 is a device that uses hardware or low-level software to perform a transfer process for transferring communication data between the first wired communication unit 12 and the first wireless communication unit 14. The transfer process performed by the communication accelerator 16 includes, for example, a process of extracting IP packets from an Ethernet communication frame received by the first wired communication unit 12 and outputting the IP packets to the first wireless communication unit 14. The transfer process performed by the communication accelerator 16 may also include a process of discarding communication data that is not an IP packet or a process of returning communication data that is not an IP packet to the sender.

[0028] As shown in FIG. 2, the control unit 11 of the communication device 2 includes a transfer control unit 31, a switching condition determination unit 32, and a route switching unit 33 as functional blocks realized by the CPU 21 executing a program stored in the ROM 22.

[0029] Similar to the communication accelerator 16, the transfer control unit 31 performs, for example, a process of extracting IP packets from Ethernet communication frames received by the first wired communication unit 12 and outputting the IP packets to the first wireless communication unit 14. Furthermore, the transfer control unit 31 has a function of estimating the communication states of the first wireless communication unit 14 and the second wireless communication unit 15, and suspending the transfer of communication data or changing the transfer destination of the communication data for each communication flow. A communication flow is, for example, a collection of multiple Ethernet communication frames that all have the same source address, destination address, transmission port, and reception port.

[0030] The transfer control unit 31 estimates the communication status of the first and second wireless communication units 14 and 15, for example, by measuring the communication speed of the first and second wireless communication units 14 and 15, or by measuring the delay time between sending a packet to the first and second wireless communication units 14 and 15 and receiving a reply.

[0031] The switching condition determination unit 32 determines whether a preset route switching condition is met. The route switching condition is a condition under which it becomes necessary to control the total amount of data transferred to the first wireless communication unit 14. The route switching condition includes, for example, at least one of a first switching condition, a second switching condition, a third switching condition, a fourth switching condition, and a fifth switching condition, which will be described later.

[0032] The first switching condition is, for example, that high-priority communication (hereinafter referred to as high-priority communication) is being performed in the first wireless communication unit 14. The switching condition determination unit 32 determines whether high-priority communication is being performed based on a source address and a destination address included in a communication frame in which the first wireless communication unit 14 is performing wireless communication.

[0033] The second switching condition is to receive a high-priority communication start notification indicating that high-priority communication is to be started, or a condition establishment notification indicating that the route switching condition is established, from a program installed in the communication device 2 or from ECUs 3, 4, and 5.

[0034] The third switching condition is that the vehicle equipped with the communication system 1 (hereinafter referred to as the host vehicle) is located in a wireless communication unstable area that is preset as an area where radio waves of wireless communication are difficult to reach.

[0035] The fourth switching condition is that a failure or congestion occurs in the first wireless communication unit 14 .

[0036] The fifth switching condition is that there is a high possibility of an accident occurring in or around the host vehicle. For example, the fifth switching condition is that there is a high possibility of a collision occurring in the host vehicle or that there is an emergency vehicle approaching the host vehicle, which is received from ECU 3 or ECU 4.

[0037] When the path switching condition is not satisfied, the path switching unit 33 sets the transfer path for transferring the communication frames transmitted by the ECUs 3, 4, and 5 to pass through the communication accelerator 16, as indicated by arrows L1 and L2. The arrow L1 indicates the transfer path for communication frames of high-priority communication (hereinafter referred to as high-priority communication frames). The arrow L2 indicates the transfer path for communication frames other than high-priority communication frames (hereinafter referred to as low-priority communication frames).

[0038] Specifically, the path switching unit 33 outputs a relay command to the network switch 6 to set the network switch 6 to relay high-priority communication frames transmitted from the ECUs 3, 4, and 5 to the first wired communication unit 12, and to relay low-priority communication frames transmitted from the ECUs 3, 4, and 5 to the first wired communication unit 12. The network switch 6 determines whether a frame is a high-priority communication frame, for example, based on the source address and destination address included in the Ethernet communication frame.

[0039] 3, when the path switching condition is met, the path switching unit 33 sets the transfer path for transferring a communication frame received by the first wired communication unit 12 to pass through the transfer control unit 31, as indicated by arrows L3 and L4. Arrow L3 indicates the transfer path for high-priority communication frames. Arrow L4 indicates the transfer path for low-priority communication frames.

[0040] Specifically, the path switching unit 33 outputs a relay command to the network switch 6 to set it to relay high-priority communication frames transmitted from ECUs 3, 4, and 5 to the second wired communication unit 13, and to relay non-priority communication frames transmitted from ECUs 3, 4, and 5 to the second wired communication unit 13.

[0041] The transfer control unit 31 is configured to transfer a high-priority communication frame to the second wireless communication unit 15 when the communication state of the first wireless communication unit 14 is not good and the communication state of the second wireless communication unit 15 is good.

[0042] The communication device 2 configured in this manner includes a transfer control unit 31 , a communication accelerator 16 , a switching condition determination unit 32 , and a path switching unit 33 .

[0043] The transfer control unit 31 is configured to be able to change the transfer method for transferring input communication data in accordance with the communication state of the first wireless communication unit 14 configured to perform data communication.

[0044] The communication accelerator 16 includes hardware configured to perform data communication and capable of executing the process of transferring communication data from a first wired communication unit 12, which is different from the first wireless communication unit 14, to the first wireless communication unit 14 faster than the transfer control unit 31.

[0045] The switching condition determining unit 32 is configured to determine whether a preset path switching condition indicating that transfer of communication data to the first wireless communication unit 14 needs to be suppressed is met.

[0046] The route switching unit 33 is configured to switch the transfer route of the communication data by executing the process of transferring the communication data using the transfer control unit 31 without going through the communication accelerator 16 when the route switching condition is met.

[0047] In such a communication device 2, during normal times when the path switching condition is not satisfied, the process of transferring communication data is executed via the communication accelerator 16, and during abnormal times when the path switching condition is satisfied, the process of transferring communication data can be executed using the transfer control unit 31. Therefore, during abnormal times when the path switching condition is satisfied, the communication device 2 can apply processes not supported by the communication accelerator 16 using the transfer control unit 31, while effectively utilizing the communication accelerator 16, which can execute the process of transferring communication data faster than the transfer control unit 31 in order to speed up communication during normal times, thereby achieving both the transfer process required during abnormal times and the high-speed data communication during normal times. Note that, during abnormal times when the path switching condition is satisfied, the communication device 2 executes the process of transferring communication data using the transfer control unit 31, thereby ensuring data communication using transfer processes that are useful for responding to abnormal times and that can be executed by the transfer control unit 31, i.e., transfer processes including estimating the communication state, suspending the transfer of communication data for each communication flow, or changing the transfer destination of communication data, even when these processes are impossible or difficult to execute using the communication accelerator 16.

[0048] The path switching unit 33 is configured to switch the transfer path by causing the network switch 6 to change the output destination of communication data input to the network switch 6 from the first wired communication unit 12 to the second wired communication unit 13. The network switch 6 is installed outside the communication device 2, and is configured to switch the output destination of the communication data by outputting the input communication data to either the first wired communication unit 12, the first wireless communication unit 14 configured to perform data communication, or a second wired communication unit 13 different from the first wired communication unit 12.

[0049] The communication device 2 can switch the transfer path of communication data in accordance with the path switching conditions even if the communication accelerator 16 is configured not to reflect the switching of the transfer path. Furthermore, the communication device 2 can reduce the processing load for switching the transfer path of communication data.

[0050] The communication device 2 is mounted on a vehicle. The switching condition determination unit 32 is configured to determine that the route switching condition is met when an emergency notification indicating a high level of urgency in the vehicle's state (in this embodiment, a high level of urgency in the vehicle's collision) or a high level of urgency in the traffic situation around the vehicle (in this embodiment, an approaching emergency vehicle) is received from outside the communication device 2. Based on the emergency notification, the communication device 2 recognizes that a high-priority communication is likely to occur and switches the transfer path so that the process of transferring communication data is performed using the transfer control unit 31 without going through the communication accelerator 16. Therefore, the communication device 2 can prevent a situation in which necessary communication is not performed when the vehicle's state is highly urgency or when the traffic situation around the vehicle is highly urgency.

[0051] In the above-described embodiment, the first wireless communication unit 14 corresponds to the first communication unit, the first wired communication unit 12 corresponds to the second communication unit, the second wired communication unit 13 corresponds to the third communication unit, and the network switch 6 corresponds to the output switching unit.

[0052] Second Embodiment A second embodiment of the present disclosure will be described below with reference to the drawings. In the second embodiment, differences from the first embodiment will be described. The same reference numerals will be used to designate common components.

[0053] As shown in FIGS. 4 and 5, the communication system 1 of the second embodiment differs from the first embodiment in that the transfer path for high-priority communication frames is changed.

[0054] When the path switching condition is not satisfied, the path switching unit 33 of the second embodiment sets the transfer path for transferring high-priority communication frames transmitted by the ECUs 3, 4, and 5 to pass through the transfer control unit 31, and sets the transfer path for transferring low-priority communication frames transmitted by the ECUs 3, 4, and 5 to pass through the communication accelerator 16, as shown by arrows L11 and L12 in Fig. 4. Arrow L11 indicates the transfer path for high-priority communication frames. Arrow L12 indicates the transfer path for low-priority communication frames.

[0055] Specifically, the path switching unit 33 outputs a relay command to the network switch 6 to set it to relay high-priority communication frames transmitted from ECUs 3, 4, and 5 to the second wired communication unit 13, and to relay non-priority communication frames transmitted from ECUs 3, 4, and 5 to the first wired communication unit 12.

[0056] When the path switching condition is met, the path switching unit 33 of the second embodiment sets the transfer path for transferring high-priority communication frames transmitted by the ECUs 3, 4, and 5 to pass through the transfer control unit 31, and sets the transfer path for transferring low-priority communication frames transmitted by the ECUs 3, 4, and 5 to pass through the transfer control unit 31, as shown by arrows L13 and L14 in Fig. 5. Arrow L13 indicates the transfer path for high-priority communication frames. Arrow L14 indicates the transfer path for low-priority communication frames.

[0057] Specifically, the path switching unit 33 outputs a relay command to the network switch 6 to set it to relay high-priority communication frames transmitted from ECUs 3, 4, and 5 to the second wired communication unit 13, and to relay non-priority communication frames transmitted from ECUs 3, 4, and 5 to the second wired communication unit 13.

[0058] Such a communication device 2 is configured so that communication data of high-priority communication, which is preset as communication with a high priority, is transferred using the transfer control unit 31 without passing through the communication accelerator 16, regardless of whether the path switching condition is met. This allows the communication device 2 to suppress packet loss, which is the loss of communication data of high-priority communication due to switching of the transfer path.

[0059] Third Embodiment A third embodiment of the present disclosure will be described below with reference to the drawings. In the third embodiment, differences from the first embodiment will be described. The same reference numerals will be used to designate common components.

[0060] As shown in FIG. 6, the communication system 1 of the third embodiment differs from the first embodiment in that the network switch 6 and the second wired communication unit 13 are omitted and a route branching unit 18 is added.

[0061] The first wired communication unit 12 is connected to the ECUs 3 , 4 , and 5 .

[0062] In accordance with instructions from the communication accelerator 16, the route branching unit 18 switches the transfer route of the communication frame so that the communication frame input from the first wired communication unit 12 is output to either the communication accelerator 16 or the control unit 11.

[0063] When the path switching condition is not satisfied, the path switching unit 33 of the third embodiment sets the transfer path for transferring the communication frame transmitted by the ECUs 3, 4, and 5 to pass through the communication accelerator 16, as shown by arrows L21 and L22 in Fig. 7. The arrow L21 indicates the transfer path for the high-priority communication frame. The arrow L22 indicates the transfer path for the low-priority communication frame.

[0064] Specifically, the route switching unit 33 outputs a branch command to the route branching unit 18 via the communication accelerator 16 to set the route branching unit 18 to switch to a transfer route that transfers communication frames from the first wired communication unit 12 to the communication accelerator 16.

[0065] When the path switching condition is met, the path switching unit 33 of the third embodiment sets the path to go through the transfer control unit 31, as shown by arrows L23 and L24 in Fig. 8. Arrow L23 indicates the transfer path for high-priority communication frames. Arrow L24 indicates the transfer path for low-priority communication frames.

[0066] Specifically, the route switching unit 33 outputs a branching command to the route branching unit 18 via the communication accelerator 16 to set the route branching unit 18 to switch to a transfer route that transfers communication frames from the first wired communication unit 12 to the control unit 11.

[0067] The communication device 2 configured in this manner includes a transfer control unit 31 , a communication accelerator 16 , a switching condition determination unit 32 , and a path switching unit 33 .

[0068] In such a communication device 2, during normal times when the path switching condition is not satisfied, the process of transferring communication data is executed via the communication accelerator 16, and during abnormal times when the path switching condition is satisfied, the process of transferring communication data is executed using the transfer control unit 31. Therefore, in order to speed up communication, the communication device 2 can effectively utilize the communication accelerator 16, which can execute the process of transferring communication data faster than the transfer control unit 31, and can speed up data communication.

[0069] The route switching unit 33 is configured to switch the transfer route by causing the route branching unit 18 to change the output destination of the communication data input to the first wired communication unit 12 from the communication accelerator 16 to the control unit 11.

[0070] Although one embodiment of the present disclosure has been described above, the present disclosure is not limited to the above embodiment and can be implemented in various modifications.

[0071] [Modification 1] In the third embodiment, the path switching unit 33 outputs a branch command to the communication accelerator 16. However, the communication accelerator 16 may check with the control unit 11 whether or not a path switching condition is satisfied, and output a branch command to the path branching unit 18 according to the check result.

[0072] [Modification 2] In the first embodiment described above, the communication device 2 includes the first and second wired communication units 12 and 13 and the first and second wireless communication units 14 and 15. However, the first and second wired communication units 12 and 13 and the first and second wireless communication units 14 and 15 may be multiple virtual communication units realized by virtually dividing them using software.

[0073] The control unit 11 and the method described herein may be implemented by a special-purpose computer configured by configuring a processor and memory programmed to execute one or more functions embodied in a computer program. Alternatively, the control unit 11 and the method described herein may be implemented by a special-purpose computer configured by configuring a processor with one or more dedicated hardware logic circuits. Alternatively, the control unit 11 and the method described herein 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 the control unit 11 does not necessarily need to include software; all of the functions may be implemented using one or more hardware components.

[0074] In the above embodiments, multiple functions of one component may be realized by multiple components, or one function of one component may be realized by multiple components. Furthermore, multiple functions of multiple components may be realized by one component, or one function realized by multiple components may be realized by one component. Furthermore, 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.

[0075] In addition to the communication device 2 described above, the present disclosure can also be realized in various forms, such as a system including the communication device 2 as a component, a program for causing a computer to function as the communication device 2, a non-transient physical recording medium such as a semiconductor memory on which this program is recorded, and a communication method. [Technical Ideas Disclosed in the Present Specification] [Item 1] A communication device (2) comprising: a transfer control unit (31) configured to be able to change a transfer method for transferring input communication data in accordance with the communication state of a first communication unit (14) configured to perform data communication; a communication accelerator (16) including hardware capable of executing a process of transferring the communication data from a second communication unit (12) configured to perform data communication and different from the first communication unit to the first communication unit faster than the transfer control unit; a switching condition determination unit (32) configured to determine whether a preset path switching condition indicating that transfer of the communication data to the first communication unit needs to be suppressed is established; and a path switching unit (33) configured to switch a transfer path for the communication data when the path switching condition is established, by executing the process of transferring the communication data using the transfer control unit without going through the communication accelerator.

[0076] [Item 2] The communication device according to Item 1, wherein the path switching unit is installed outside the communication device and is configured to output the input communication data to either the second communication unit or a third communication unit (13) configured to perform data communication and different from the first communication unit and the second communication unit, and to switch the output destination of the communication data by causing an output switching unit (6) configured to change the output destination of the communication data input to the output switching unit from the second communication unit to the third communication unit, thereby switching the transfer path.

[0077] [Item 3] The communication device according to item 1 or 2, wherein the communication data of a high-priority communication that is preset as a high-priority communication is transferred using the transfer control unit without passing through the communication accelerator, regardless of whether the path switching condition is satisfied.

[0078] [Item 4] The communication device according to any one of Items 1 to 3, wherein the communication device is mounted on a vehicle, and the switching condition determination unit is configured to determine that the route switching condition is met when an emergency notification indicating that the state of the vehicle is highly urgent or that the traffic situation around the vehicle is highly urgent is acquired from outside the communication device.

[0079] [Item 5] A communication program for causing a computer of a communication device (2) including: a transfer control unit (31) configured to be able to change a transfer method for transferring input communication data in accordance with a communication state of a first communication unit (14) configured to perform data communication; and a communication accelerator (16) including hardware capable of executing a process of transferring the communication data from a second communication unit (12) configured to perform data communication and different from the first communication unit to the first communication unit faster than the transfer control unit; the communication program causing a computer of a communication device (2) to function as: a switching condition determination unit (32) configured to determine whether a preset path switching condition indicating that transfer of the communication data to the first communication unit needs to be suppressed is established; and a path switching unit (33) configured to switch the transfer path of the communication data by executing the process of transferring the communication data using the transfer control unit without going through the communication accelerator when the path switching condition is established.

Claims

1. A communication device (2) comprising: a transfer control unit (31) configured to be able to change a transfer method for transferring input communication data in accordance with the communication state of a first communication unit (14) configured to perform data communication; a communication accelerator (16) including hardware capable of executing a process of transferring the communication data from a second communication unit (12) configured to perform data communication and different from the first communication unit to the first communication unit faster than the transfer control unit; a switching condition determination unit (32) configured to determine whether a preset path switching condition indicating that transfer of the communication data to the first communication unit needs to be suppressed is established; and a path switching unit (33) configured to switch the transfer path of the communication data when the path switching condition is established, by executing the process of transferring the communication data using the transfer control unit without going through the communication accelerator.

2. A communication device as described in claim 1, wherein the path switching unit is installed outside the communication device and is configured to output the input communication data to either the second communication unit or a third communication unit (13) configured to perform data communication and different from the first communication unit and the second communication unit, and to switch the transfer path by causing an output switching unit (6) configured to switch the output destination of the communication data input to the output switching unit to change the output destination of the communication data from the second communication unit to the third communication unit.

3. A communication device as claimed in claim 1 or claim 2, wherein the communication data of a high-priority communication that has been preset as a high-priority communication is transferred using the transfer control unit without passing through the communication accelerator, regardless of whether the path switching condition is met.

4. A communication device as claimed in claim 1 or claim 2, wherein the communication device is mounted on a vehicle, and the switching condition determination unit is configured to determine that the route switching condition is met when an emergency notification indicating that the vehicle's condition is highly urgent or that the traffic situation around the vehicle is highly urgent is received from outside the communication device.

5. A communication program for causing a computer of a communication device (2) comprising: a transfer control unit (31) configured to be able to change the transfer method for transferring input communication data in accordance with the communication status of a first communication unit (14) configured to perform data communication; and a communication accelerator (16) including hardware capable of executing a process of transferring the communication data from a second communication unit (12) configured to perform data communication and different from the first communication unit to the first communication unit faster than the transfer control unit; a switching condition determination unit (32) configured to determine whether a preset route switching condition indicating the need to suppress the transfer of the communication data to the first communication unit has been established; and a route switching unit (33) configured to switch the transfer route of the communication data by executing the process of transferring the communication data using the transfer control unit without going through the communication accelerator when the route switching condition has been established.

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