On-vehicle communication system, on-vehicle relay device, and relay method

Abstract

To reduce a bus load while suppressing the impact on relay processing of a frame in an on-vehicle network.SOLUTION: An on-vehicle communication system includes a plurality of on-vehicle devices, and a plurality of on-vehicle relay devices including a first on-vehicle relay device and a second on-vehicle relay device connected via a communication bus to the first on-vehicle relay device. The on-vehicle relay devices perform relay processing of relaying frames transmitted and received among the on-vehicle devices. The first on-vehicle relay device performs compression processing of compressing the frames, and transmits the frames after the compression processing to the second on-vehicle relay device via the communication bus. The second on-vehicle relay device performs expansion processing of expanding the frames after the compression processing received from the first on-vehicle relay device and performs the relay processing on the frames after the expansion processing.SELECTED DRAWING: Figure 8

Description

Technical Field

[0001] The present disclosure relates to an in-vehicle communication system, an in-vehicle relay device, and a relay method.

Background Art

[0002] Conventionally, in an in-vehicle relay device that relays frames transmitted and received between in-vehicle devices, a technique for monitoring the bus load on the communication bus of the relay destination of the frame has been developed. For example, Patent Document 1 (Japanese Patent Application Laid-Open No. 2006-287738) discloses the following network system. That is, in a network system including a gateway node to which at least one of the connection destinations is connected to a CAN bus network, the gateway node includes bus load monitoring means for monitoring the frame transmitted to the CAN bus and monitoring the bus load state on the CAN bus.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In recent years, the types of services executed in in-vehicle networks have tended to increase. In this case, the bus load in the in-vehicle network may increase.

[0005] In the network system described in Patent Document 1, when the bus load is large, processing for reducing the data length of the frame to be relayed and processing for stopping the frame relay processing are performed. However, when such processing is performed, there is a possibility that the data that the in-vehicle device at the destination of the frame should acquire is deleted or that frame relay omission occurs.

[0006] The present disclosure has been made to solve the above-described problems, and an object thereof is to provide an in-vehicle communication system, an in-vehicle relay device, and a relay method capable of reducing the bus load while suppressing the influence on the frame relay process in the in-vehicle network.

Means for Solving the Problems

[0007] The in-vehicle communication system of the present disclosure includes a plurality of in-vehicle devices, a first in-vehicle relay device, and a plurality of in-vehicle relay devices including a second in-vehicle relay device connected to the first in-vehicle relay device via a communication bus. The in-vehicle relay device performs a relay process of relaying frames transmitted and received between the in-vehicle devices. The first in-vehicle relay device performs a compression process of compressing the frame, and transmits the compressed frame to the second in-vehicle relay device via the communication bus. The second in-vehicle relay device performs an expansion process of expanding the compressed frame received from the first in-vehicle relay device, and performs the relay process of the expanded frame.

[0008] One aspect of the present disclosure can be realized not only as an in-vehicle communication system including such a characteristic processing unit, but also as a method including such characteristic processes as steps, or as a program for causing a computer to execute such steps. Further, one aspect of the present disclosure can be realized as a semiconductor integrated circuit that realizes part or all of the in-vehicle communication system.

[0009] One aspect of the present disclosure can be realized not only as an in-vehicle relay device including such a characteristic processing unit, but also as a program for causing a computer to execute the steps of such characteristic processes. Further, one aspect of the present disclosure can be realized as a semiconductor integrated circuit that realizes part or all of the in-vehicle relay device.

Advantages of the Invention

[0010] According to the present disclosure, it is possible to reduce the bus load while suppressing the influence on the frame relay process in the in-vehicle network.

Brief Description of the Drawings

[0011]

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Embodiments for Carrying Out the Invention

[0012] First, the content of the embodiments of the present disclosure will be listed and described. (1) The in-vehicle communication system according to the embodiment of the present disclosure includes a plurality of in-vehicle devices, a first in-vehicle relay device, and a plurality of in-vehicle relay devices including a second in-vehicle relay device connected to the first in-vehicle relay device via a communication bus. The in-vehicle relay device performs a relay process of relaying frames transmitted and received between the in-vehicle devices. The first in-vehicle relay device performs a compression process of compressing the frame, and transmits the compressed frame to the second in-vehicle relay device via the communication bus. The second in-vehicle relay device performs an expansion process of expanding the compressed frame received from the first in-vehicle relay device, and performs the relay process of the expanded frame.

[0013] In this way, in the first in-vehicle relay device, by compressing the frame to be relayed and outputting it to the bus of the relay destination, the communication load of the bus can be reduced while eliminating the need to stop the relay process and reduce frame data. Therefore, the bus load can be reduced while suppressing the influence on the frame relay process in the in-vehicle network. Further, in the second in-vehicle relay device, by expanding the frame compressed by the first in-vehicle relay device and relaying the expanded frame, the expansion process in the in-vehicle device of the frame destination becomes unnecessary, so that the processing load in the in-vehicle device can be reduced.

[0014] (2) In the above (1), the first in-vehicle relay device may perform a first determination process of determining a compression target frame that is the frame to be compressed from the received frames, and perform the compression process on the determined compression target frame. The second in-vehicle relay device may perform a second determination process of determining an expansion target frame that is the frame to be expanded from the received frames, and perform the expansion process on the determined expansion target frame.

[0015] With such a configuration, since compression processing and decompression processing can be selectively performed, frame transmission can be efficiently performed for the entire in-vehicle communication system.

[0016] (3) In the above (2), the first in-vehicle relay device may hold first identification information corresponding to the frame to be compressed, and perform the first determination process using the held first identification information. The second in-vehicle relay device may hold second identification information corresponding to the frame to be decompressed, and perform the second determination process using the held second identification information.

[0017] With such a configuration, in the first in-vehicle relay device, a frame to be compressed can be more accurately determined with simple processing. Also, in the second in-vehicle relay device, a frame to be decompressed can be more accurately determined with simple processing.

[0018] (4) In any of (1) to (3) above, the first in-vehicle relay device may not perform the compression process on the operation frame, which is the frame related to the operation of the vehicle on which the in-vehicle communication system is mounted.

[0019] For example, since the allowable delay time of a frame related to vehicle operation is short, by outputting the frame to the relay destination bus without compressing the frame, it is possible to suppress the frame from being transmitted beyond the allowable delay time.

[0020] (5) In any of (1) to (4) above, the first in-vehicle relay device may receive the frame conforming to the CAN standard, and the first in-vehicle relay device may transmit the frame after the compression process with a specific CAN-ID for compression processing to the second in-vehicle relay device via the communication bus.

[0021] With such a configuration, it is possible to easily recognize that the received frame is a frame after compression processing.

[0022] (6) In any of the above (1) to (5), the first in-vehicle relay device may determine whether to perform the compression process based on the estimated result of the communication load on the communication bus.

[0023] With such a configuration, for example, when a situation where the communication load of the bus at the relay destination is expected to increase is assumed, by performing the compression process, the communication load of the bus can be more reliably reduced. Also, since the number of times of performing the compression process can be reduced according to the communication load, the processing load in the first in-vehicle relay device can be reduced.

[0024] (7) In any of the above (1) to (6), the in-vehicle communication system may include three or more of the in-vehicle relay devices, and the third in-vehicle relay device may not perform the compression process and the decompression process.

[0025] For example, in a configuration where the in-vehicle communication system includes three or more in-vehicle relay devices, among the three or more in-vehicle relay devices, the communication load of the communication bus to which a certain in-vehicle relay device is connected may be smaller than the communication load of the communication bus to which other in-vehicle relay devices are connected. With the above configuration, when it is not necessary to reduce the communication load of a certain communication bus, by not performing the compression process and the decompression process in the in-vehicle relay device connected to the communication bus, the processing load in the in-vehicle relay device can be reduced. Also, by performing the compression process in the in-vehicle relay device connected to the communication bus for which the communication load is to be reduced, the bus load can be efficiently reduced for the entire in-vehicle communication system.

[0026] (8) The in-vehicle relay device according to an embodiment of the present disclosure is used in an in-vehicle communication system including a plurality of in-vehicle devices, and is an in-vehicle relay device that performs a relay process for relaying frames transmitted and received between the in-vehicle devices. The in-vehicle relay device is connected to other in-vehicle relay devices via a communication bus, and includes a relay unit that receives the frames and a compression processing unit that performs a compression process for compressing the frames received by the relay unit. The relay unit transmits the frames after the compression process by the compression processing unit to the other in-vehicle relay devices via the communication bus.

[0027] In this way, by adopting a configuration in which the frames to be relayed are compressed and output to the bus of the relay destination, it is possible to reduce the communication load on the bus while eliminating the need to stop the relay process and reduce the frame data. Therefore, it is possible to reduce the bus load while suppressing the influence on the frame relay process in the in-vehicle network.

[0028] (9) In the above (8), the relay unit may further receive the frames after the compression process transmitted from the other in-vehicle relay devices. The in-vehicle relay device may further include a decompression processing unit that performs a decompression process for decompressing the frames after the compression process received by the relay unit. The relay unit may perform the relay process for the frames after the decompression process by the decompression processing unit.

[0029] With such a configuration, in the communication bus connecting a plurality of in-vehicle relay devices, the frames after the compression process can be transmitted bidirectionally, so that the communication load on the communication bus can be further reduced.

[0030] (10) The relay method according to an embodiment of the present disclosure is a relay method in an in-vehicle relay device that is used in an in-vehicle communication system including a plurality of in-vehicle devices and performs a relay process of relaying frames transmitted and received between the in-vehicle devices. The in-vehicle relay device is connected to other in-vehicle relay devices via a communication bus, and includes a step of receiving the frame, a step of performing a compression process of compressing the received frame, and a step of transmitting the frame after the compression process to the other in-vehicle relay device via the communication bus.

[0031] In this way, by compressing the frame to be relayed and outputting it to the bus of the relay destination, it is possible to reduce the communication load of the bus while eliminating the need to stop the relay process and reduce the frame data. Therefore, it is possible to reduce the bus load while suppressing the influence on the frame relay process in the in-vehicle network.

[0032] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and their descriptions will not be repeated. Also, at least a part of the embodiments described below may be arbitrarily combined.

[0033] <First Embodiment> FIG. 1 is a diagram showing the configuration of an in-vehicle communication system according to a first embodiment of the present disclosure. Referring to FIG. 1, the in-vehicle communication system 301 includes a plurality of in-vehicle relay devices 101 and a plurality of in-vehicle ECUs (Electronic Control Units) 202. The in-vehicle relay device 101 is used in an in-vehicle communication system 301 including a plurality of in-vehicle ECUs 202. The in-vehicle communication system 301 is mounted on a vehicle 1. The in-vehicle ECU 202 is an example of an in-vehicle device.

[0034] In the example shown in FIG. 1, the in-vehicle communication system 301 includes in-vehicle relay devices 101A and 101B, which are in-vehicle relay devices 101, and in-vehicle ECUs 202A, 202B, 202C, 202D, 202E, 202F, and 202G, which are in-vehicle ECUs 202. The in-vehicle relay device 101A is an example of a first in-vehicle relay device, and the in-vehicle relay device 101B is an example of a second in-vehicle relay device.

[0035] Note that the in-vehicle communication system 301 is not limited to a configuration including seven in-vehicle ECUs 202, and may have a configuration including two or more and six or fewer or eight or more in-vehicle ECUs 202.

[0036] The in-vehicle ECU 202 is, for example, a TCU (Telematics Communication Unit), an engine ECU, an autonomous driving ECU, a brake control ECU, an airbag control ECU, a door lock ECU, etc. Note that the in-vehicle communication system 301 may include in-vehicle devices such as sensors, navigation devices, human-machine interfaces, and cameras in addition to or instead of the in-vehicle ECU 202.

[0037] The plurality of in-vehicle relay devices 101 and the plurality of in-vehicle ECUs 202 constitute an in-vehicle network 401. The plurality of in-vehicle ECUs 202 are connected to the in-vehicle relay device 101 via a CAN bus 51 that conforms to the CAN (Controller Area Network) standard, for example. The CAN bus 51 is an example of a communication bus.

[0038] In the example shown in FIG. 1, the in-vehicle ECUs 202A, 202B, and 202C are connected to the in-vehicle relay device 101A via a CAN bus 51A, which is the CAN bus 51. The in-vehicle ECU 202F is connected to the in-vehicle relay device 101A and the in-vehicle relay device 101B via a CAN bus 51B, which is the CAN bus 51. The in-vehicle ECU 202G is connected to the in-vehicle relay device 101A via a CAN bus 51C, which is the CAN bus 51. The in-vehicle ECUs 202D and 202E are connected to the in-vehicle relay device 101B via a CAN bus 51D, which is the CAN bus 51.

[0039] The in-vehicle relay device 101 relays frames transmitted and received between a plurality of in-vehicle ECUs 202 connected to itself.

[0040] The in-vehicle relay device 101B is connected to the in-vehicle relay device 101A via the CAN bus 51B.

[0041] Hereinafter, the CAN bus 51A is also referred to as "CAN1", the CAN bus 51B is also referred to as "CAN2", the CAN bus 51C is also referred to as "CAN3", and the CAN bus 51D is also referred to as "CAN4".

[0042] For example, each in-vehicle ECU 202 transmits a CAN frame, which is a frame conforming to the CAN standard, to another in-vehicle ECU 202 or the in-vehicle relay device 101.

[0043] Specifically, for example, each in-vehicle ECU 202 transmits a CAN frame including information for assisting the automatic driving performed by the vehicle 1, various information such as information used for entertainment, and a CAN-ID (Identifier) indicating the type of data, etc., to another in-vehicle ECU 202 or the in-vehicle relay device 101.

[0044] FIG. 2 is a diagram showing an example of a CAN frame transmitted by an in-vehicle ECU in an in-vehicle communication system according to the first embodiment of the present disclosure. Referring to FIG. 2, the CAN frame has, in this order from the head of the frame, a SOF (Start Of Frame) field, an ID field, an RTR (Remote Transmission Request) field, a CONTROL field, a data field (hereinafter also referred to as a DAT field), a CRC (Cyclic Redundancy Check) field, an ACK field, and an EOF (End Of Frame) field.

[0045] FIG. 3 is a diagram showing the configuration of an in-vehicle relay device according to the first embodiment of the present disclosure. Referring to FIG. 3, the in-vehicle relay device 101 includes a relay unit 11, a processing unit 12, and a storage unit 13. The processing unit 12 includes a determination unit 21, a compression processing unit 22, a decompression processing unit 23, and a monitoring unit 24. One or both of the relay unit 11 and the processing unit 12 are realized by, for example, a processing circuit (Circuitry) including one or more processors. The storage unit 13 is, for example, a non-volatile memory included in the processing circuit.

[0046] The relay unit 11 receives a CAN frame transmitted from a certain in-vehicle ECU 202 or another in-vehicle relay device 101. Then, the relay unit 11 checks whether the received CAN frame is a CAN frame that the own in-vehicle relay device 101 should receive.

[0047] FIG. 4 is a diagram showing an example of a reception list stored by the in-vehicle relay device according to the first embodiment of the present disclosure. FIG. 4 shows an example of a reception list L stored by the in-vehicle relay device 101A.

[0048] Referring to FIGS. 3 and 4, the storage unit 13 stores, for example, a reception list L indicating the CAN-ID included in the CAN frame that the own in-vehicle relay device 101A should receive. The reception list L is registered in the storage unit 13 by the manufacturer of the vehicle 1, for example, at the time of shipment of the vehicle 1.

[0049] In the reception list L shown in FIG. 4, the CAN-ID included in the CAN frame that the in-vehicle relay device 101A should receive is "0x000", "0x001", "0x002", "0x003", "0x004", or "0x100".

[0050] When receiving a CAN frame, the relay unit 11 checks whether the CAN-ID included in the CAN frame is registered in the reception list L by referring to the reception list L in the storage unit 13.

[0051] If the CAN-ID included in the received CAN frame is not registered in the reception list L, for example, the relay unit 11 discards the CAN frame. On the other hand, if the CAN-ID included in the received CAN frame is registered in the reception list L, for example, the relay unit 11 stores the CAN frame in the storage unit 13 and outputs ID information E1 indicating the CAN-ID to the discrimination unit 21 and the monitoring unit 24.

[0052] [Compression processing] The compression processing unit 22 performs compression processing to compress the CAN frame received by the relay unit 11.

[0053] More specifically, for example, the storage unit 13 holds a CAN-ID (hereinafter also referred to as "compression target ID") corresponding to a CAN frame to be compressed (hereinafter also referred to as "compression target frame"). The compression target ID is an example of the first identification information.

[0054] Specifically, for example, the reception list L shown in FIG. 4 further includes a discrimination flag. The discrimination flag indicates whether the CAN-ID registered in the reception list L is a compression target ID.

[0055] In the reception list L, the discrimination flag "1" indicates that the CAN-ID registered in the reception list L is a compression target ID. The discrimination flag "0" indicates that the CAN-ID is not a compression target ID.

[0056] For example, the compression processing unit 22 does not perform compression processing on a CAN frame related to the operation of the vehicle 1 (hereinafter also referred to as "operation frame"). For example, the operation frame is a CAN frame including information for controlling the brakes of the vehicle 1 or information for controlling the airbag of the vehicle 1. In the reception list L, the discrimination flag corresponding to the CAN-ID included in the operation frame is set to "0".

[0057] In the reception list L shown in FIG. 4, for example, the discrimination flags for CAN-IDs “0x000”, “0x001” or “0x003” are “1”. The discrimination flags for CAN-IDs “0x002” or “0x100” are “0”.

[0058] (Discrimination process D1) Referring again to FIG. 3, the discrimination unit 21 performs a discrimination process D1 for discriminating a compression target frame from among the CAN frames received by the relay unit 11. The discrimination process D1 is an example of a first discrimination process.

[0059] More specifically, for example, the discrimination unit 21 performs the discrimination process D1 using the compression target ID. For example, every time the discrimination unit 21 receives ID information E1 from the relay unit 11, it refers to the reception list L in the storage unit 13 to check whether the discrimination flag of the CAN-ID indicated by the ID information E1 is “1”.

[0060] When the discrimination flag of the CAN-ID indicated by the ID information E1 received by the discrimination unit 21 from the relay unit 11 is “0”, the discrimination unit 21 recognizes that the CAN frame including the CAN-ID stored in the storage unit 13 is not a compression target frame. Then, the discrimination unit 21 outputs the ID information E1 to the relay unit 11.

[0061] FIG. 5 is a diagram showing an example of a routing table stored in the in-vehicle relay device according to the first embodiment of the present disclosure.

[0062] Referring to FIG. 5, the storage unit 13 stores a routing table Tb11 showing the correspondence between a CAN-ID, the CAN bus 51 to which the transmission source of the CAN frame is connected (hereinafter also referred to as the “transmission source bus”), and the CAN bus 51 to which the transmission destination of the CAN frame is connected (hereinafter also referred to as the “transmission destination bus”). The routing table Tb11 is registered in the storage unit 13 by the vehicle 1 manufacturer, for example, when the vehicle 1 is shipped.

[0063] In the routing table Tb11 shown in FIG. 5, the source bus of the CAN frame including the CAN-ID "0x000", "0x001" or "0x002" is "CAN1", and the destination bus of the CAN frame is "CAN2". The source bus of the CAN frame including the CAN-ID "0x003" is "CAN1", and the destination bus of the CAN frame is "CAN3". The source bus of the CAN frame including the CAN-ID "0x004" is "CAN4", and the destination bus of the CAN frame is "CAN1". The source bus of the CAN frame including the CAN-ID "0x100" is "not applicable", and the destination bus of the CAN frame is "CAN2".

[0064] Referring again to FIG. 2, when the relay unit 11 receives the ID information E1 from the discrimination unit 21, the relay unit 11 refers to the routing table Tb11 in the storage unit 13 to identify the destination bus corresponding to the CAN-ID indicated by the ID information E1. Then, the relay unit 11 acquires the CAN frame including the CAN-ID from the storage unit 13 and outputs the acquired CAN frame to the identified destination bus.

[0065] On the other hand, when the discrimination flag of the CAN-ID indicated by the ID information E1 received by the discrimination unit 21 from the relay unit 11 is "1", the discrimination unit 21 recognizes that the CAN frame including the CAN-ID stored in the storage unit 13 is a frame to be compressed. Then, the discrimination unit 21 outputs the ID information E1 received from the relay unit 11 to the compression processing unit 22.

[0066] (Calculation process) For example, the monitoring unit 24 performs a calculation process of calculating an estimated value of the communication load (hereinafter, also referred to as "bus load") on the CAN bus 51 to which the CAN frame is relayed.

[0067] More specifically, for example, the monitoring unit 24 calculates an estimated value of the bus load every time a calculation period T of the estimated value of the bus load elapses after the in-vehicle relay device 101 of itself is activated. The calculation period T is, for example, 1 millisecond. Note that the calculation period T is not limited to 1 millisecond and may be set to other values according to the number of in-vehicle ECUs 202 constituting the in-vehicle network 401 or the like.

[0068] Specifically, for example, every time the monitoring unit 24 receives the ID information E1 from the relay unit 11 during the calculation period T, it refers to the routing table Tb11 in the storage unit 13 to identify the destination bus corresponding to the CAN-ID indicated by the ID information E1. Then, for each identified destination bus, the monitoring unit 24 counts the number of times the ID information E1 is received from the relay unit 11 during the calculation period T, and calculates the count value as an estimated value of the bus load on the destination bus.

[0069] Note that the monitoring unit 24 is not limited to the configuration in which the above count value is calculated as an estimated value of the bus load, and may be configured to calculate the total data amount of the DAT field in each CAN frame stored in the storage unit 13 by the relay unit 11 during the calculation period T as an estimated value of the bus load.

[0070] When the monitoring unit 24 calculates an estimated value of the bus load, it outputs load information indicating the calculation result and the corresponding destination bus to the compression processing unit 22.

[0071] For example, the compression processing unit 22 determines whether to perform compression processing based on the estimated result of the bus load by the monitoring unit 24.

[0072] More specifically, for example, when the compression processing unit 22 receives one or more pieces of ID information E1 from the determination unit 21 and load information from the monitoring unit 24, it checks whether the estimated value of the bus load indicated by the load information is equal to or greater than a predetermined threshold Th.

[0073] (When the estimated value of the bus load is less than the threshold) For example, when the estimated value of the bus load indicated by the load information received from the monitoring unit 24 is less than the threshold value Th, the compression processing unit 22 determines not to perform compression processing. Then, the compression processing unit 22 refers to the routing table Tb11 in the storage unit 13 to confirm the CAN-ID (hereinafter, also referred to as the "corresponding ID") corresponding to the destination bus indicated by the load information.

[0074] When the compression processing unit 22 confirms the corresponding ID, among the one or more pieces of ID information E1 received from the discrimination unit 21, it outputs to the relay unit 11 one or more pieces of ID information E1 (hereinafter, also referred to as "ID information E11") indicating the same CAN-ID as the corresponding ID. Here, an example in which the compression processing unit 22 outputs a plurality of pieces of ID information E11 to the relay unit 11 will be described.

[0075] When the relay unit 11 receives a plurality of pieces of ID information E11 from the compression processing unit 22, it acquires from the storage unit 13 a plurality of CAN frames corresponding to the plurality of pieces of ID information E11 respectively. Then, the relay unit 11 refers to the routing table Tb11 in the storage unit 13 to specify, for each acquired CAN frame, the destination bus corresponding to the CAN-ID included in the CAN frame, and outputs the CAN frame to the specified destination bus.

[0076] (When the estimated value of the bus load is greater than or equal to the threshold value) For example, when the estimated value of the bus load indicated by the load information received from the monitoring unit 24 is greater than or equal to the threshold value Th, the compression processing unit 22 determines to perform compression processing. Then, the compression processing unit 22 performs compression processing on the compression target frame discriminated by the discrimination unit 21.

[0077] More specifically, for example, when the compression processing unit 22 determines to perform compression processing, it identifies the corresponding ID by referring to the routing table Tb11 in the storage unit 13. Then, the compression processing unit 22 acquires one or more CAN frames including the confirmed corresponding ID, that is, one or more frames to be compressed, from the storage unit 13. Hereinafter, an example will be described in which the compression processing unit 22 acquires a CAN frame FA including the CAN-ID "0x000" and a CAN frame FB including the CAN-ID "0x001" as frames to be compressed from the storage unit 13.

[0078] When the compression processing unit 22 acquires the CAN frames FA and FB from the storage unit 13, it compresses each CAN frame according to a predetermined compression method C.

[0079] FIG. 6 is a diagram showing an example of a CAN frame created by the in-vehicle relay device according to the first embodiment of the present disclosure.

[0080] Referring to FIG. 6, the compression processing unit 22 creates a CAN frame (hereinafter, also referred to as "frame F1") in which the compressed CAN frames FA and FB are stored in the DAT field.

[0081] Then, the compression processing unit 22 outputs the frame F1 with a specific CAN-ID for compression processing (hereinafter, also referred to as "compression processing ID") to the relay unit 11. Here, the compression processing ID attached to the frame F1 created by the in-vehicle relay device 101A is "0x100".

[0082] FIG. 7 is a diagram showing an example of a CAN table stored in the in-vehicle relay device according to the first embodiment of the present disclosure.

[0083] Referring to FIG. 7, the storage unit 13 stores a CAN table Tb12 showing the correspondence between the CAN-ID, the type of information included in the CAN frame, the transmission source of the CAN frame, and the destination of the CAN frame. The CAN table Tb12 is registered in the storage unit 13 by the vehicle manufacturer of the vehicle 1, for example, at the time of shipment of the vehicle 1.

[0084] In the CAN table Tb12 shown in FIG. 7, for the CAN frame that includes the CAN-ID "0x000" and the information type is "AAA", the source is in-vehicle ECU 202A and the destination is in-vehicle ECU 202E. For the CAN frame that includes the CAN-ID "0x001" and the information type is "BBB", the source is in-vehicle ECU 202B and the destination is in-vehicle ECU 202D. For the CAN frame that includes the CAN-ID "0x002" and the information type is "CCC", the source is in-vehicle ECU 202C and the destination is in-vehicle ECU 202F. For the CAN frame that includes the CAN-ID "0x003" and the information type is "DDD", the source is in-vehicle ECU 202A and the destination is in-vehicle ECU 202G. For the CAN frame that includes the CAN-ID "0x004" and the information type is "EEE", the source is in-vehicle ECU 202D and the destination is in-vehicle ECU 202B. For the CAN frame that includes the CAN-ID "0x100" and the information type is "for compression processing", the source is in-vehicle relay device 101A and the destination is in-vehicle relay device 101B.

[0085] Referring to FIG. 3 again, when the compression processing unit 22 creates the frame F1, it refers to the CAN table Tb12 in the storage unit 13 to confirm the compression processing ID. Specifically, for example, the compression processing unit 22 confirms in the CAN table Tb12 that the CAN-ID corresponding to its own in-vehicle relay device 101 as the source and the CAN frame with the information type of "for compression processing" is "0x100".

[0086] When the compression processing unit 22 confirms the compression processing ID, it stores the confirmed compression processing ID in the ID field of the frame F1 and outputs it to the relay unit 11.

[0087] The relay unit 11 transmits the frame F1 created by the compression processing unit 22 to another in-vehicle relay device 101, that is, in-vehicle relay device 101B via the CAN bus 51B.

[0088] More specifically, for example, when the relay unit 11 receives the frame F1 from the compression processing unit 22, it identifies the destination bus corresponding to the compression processing ID included in the frame F1 by referring to the routing table Tb11 in the storage unit 13. Then, the relay unit 11 outputs the frame F1 to the identified destination bus, that is, the CAN bus 51B.

[0089] [Decompression processing] In the in-vehicle relay device 101B, the decompression processing unit 23 performs decompression processing to decompress the frame F1 received from the in-vehicle relay device 101A.

[0090] More specifically, for example, the discrimination unit 21 performs discrimination processing D2 to discriminate a CAN frame to be decompressed (hereinafter also referred to as a "decompression target frame") from among the CAN frames received by the relay unit 11. The discrimination processing D2 is an example of the second discrimination processing.

[0091] Specifically, for example, the storage unit 13 holds a CAN-ID (hereinafter also referred to as a "decompression target ID") corresponding to the decompression target frame. For example, the decompression target ID is the CAN-ID "0x100" corresponding to the type of information "for compression processing" included in the CAN frame registered in the CAN table Tb12 shown in FIG. 7.

[0092] For example, the discrimination unit 21 performs the discrimination processing D2 using the decompression target ID. Specifically, for example, when the discrimination unit 21 confirms that the discrimination flag of the CAN-ID included in the CAN frame received from the relay unit 11 is "0" by referring to the reception list L in the storage unit 13, it reads out the CAN table Tb12 in the storage unit 13. Then, the discrimination unit 21 confirms whether or not the CAN-ID is the same as the CAN-ID corresponding to the type of information "for compression processing" by referring to the CAN table Tb12.

[0093] When the CAN-ID indicated by the ID information E1 received from the relay unit 11 is the same as the extended target ID registered in the CAN table Tb12, that is, the CAN-ID corresponding to the information type "for compression processing", the discrimination unit 21 recognizes that the CAN frame including the CAN-ID indicated by the ID information E1 is an extended target frame. Then, the discrimination unit 21 outputs the ID information E1 received from the relay unit 11 to the extension processing unit 23.

[0094] As described above, in this embodiment, in the ID field of the frame F1 transmitted from the in-vehicle relay device 101A, the compression processing ID "0x100" is stored. The compression processing ID "0x100" is the same as the extended target ID registered in the CAN table Tb12. Therefore, the discrimination unit 21 in the in-vehicle relay device 101B recognizes that the frame F1 is an extended target frame.

[0095] For example, the extension processing unit 23 performs extension processing on the extended target frame discriminated by the discrimination unit 21.

[0096] More specifically, for example, when the extension processing unit 23 receives the ID information E1 from the discrimination unit 21, the extension processing unit 23 acquires from the storage unit 13 the CAN frame including the CAN-ID indicated by the ID information E1, that is, the extended target frame. Then, the extension processing unit 23 extends one or more compressed CAN frames stored in the DAT field of the acquired CAN frame according to the compression method C. That is, the extension processing unit 23 restores one or more CAN frames before the compression processing by the compression processing unit 22 in the in-vehicle relay device 101A. Here, it is assumed that the extension processing unit 23 restores a plurality of CAN frames.

[0097] When the extension processing is completed, the extension processing unit 23 detects the SOF field and the EOF field in the extended data and identifies one or more CAN frames. Then, the extension processing unit 23 outputs the identified CAN frames to the relay unit 11. Also, the extension processing unit 23 discards the extended target frame stored in the storage unit 13.

[0098] The relay unit 11 performs relay processing on the CAN frame after the extension processing by the extension processing unit 23. More specifically, for example, when the relay unit 11 receives a CAN frame from the extension processing unit 23, it refers to the routing table Tb11 in the storage unit 13 to identify the destination bus corresponding to the CAN-ID included in the CAN frame. Then, the relay unit 11 outputs the CAN frame to the identified destination bus.

[0099] FIG. 8 is a time chart showing an example of compression processing and extension processing by the in-vehicle relay device according to the first embodiment of the present disclosure. Similar to FIG. 6, the symbol "FA" indicates a CAN frame including the CAN-ID "0x000", and the symbol "FB" indicates a CAN frame including the CAN-ID "0x001". The in-vehicle ECU 202 that is the destination of the CAN frames FA and FB is the in-vehicle ECU 202D shown in FIG. 1.

[0100] Referring to FIG. 8, assume that the CAN frames FA and FB are output to the CAN bus 51A and the in-vehicle relay device 101A receives the CAN frames FA and FB.

[0101] When the in-vehicle relay device 101A receives the CAN frames FA and FB, it stores the CAN frames FA and FB in the storage unit 13.

[0102] Then, the in-vehicle relay device 101A performs a determination process D1 to determine whether the CAN frames FA and FB are frames to be compressed. For example, as described above, the in-vehicle relay device 101A refers to the reception list L shown in FIG. 4 to check whether the discrimination flag of the CAN-ID included in each CAN frame is "1".

[0103] When the in-vehicle relay device 101A confirms that the discrimination flag of the CAN-ID included in each of the CAN frame FA and the CAN frame FB is "1", that is, it determines that the CAN frames FA and FB are frames to be compressed.

[0104] Then, in-vehicle relay device 101A determines whether to perform compression processing according to the estimated value of the bus load on CAN bus 51B, which is the destination bus of CAN frames FA and FB, based on CAN frames FA and FB.

[0105] For example, as described above, when the estimated value of the bus load on CAN bus 51B calculated by in-vehicle relay device 101A is equal to or greater than threshold Th, in-vehicle relay device 101A performs compression processing to compress CAN frames FA and FB. Then, in-vehicle relay device 101A transmits frame F1, in which the compressed CAN frames FA and FB after compression processing are stored in the DAT field and the compression processing ID "0x100" is stored in the ID field, to in-vehicle relay device 101B via CAN bus 51B.

[0106] When in-vehicle relay device 101B receives frame F1, it performs discrimination process D2 to determine whether the received frame F1 is a frame to be decompressed using CAN table Tb12 shown in FIG. 7.

[0107] In the example shown in FIG. 8, since the CAN-ID "0x100" stored in the ID field of frame F1 in in-vehicle relay device 101B is the same as the CAN-ID corresponding to the information type "for compression processing" registered in CAN table Tb12, in-vehicle relay device 101B determines that frame F1 is a frame to be decompressed.

[0108] Then, in-vehicle relay device 101B performs decompression processing to decompress the compressed CAN frames FA and FB stored in the DAT field of frame F1, thereby restoring the CAN frames FA and FB before compression processing, and performs relay processing on the restored CAN frames FA and FB.

[0109] [Operation flow] FIGS. 9 and 10 are flowcharts defining the operation procedures when the in-vehicle relay device according to the first embodiment of the present disclosure performs compression processing and decompression processing.

[0110] Referring to FIGS. 9 and 10, first, the in-vehicle relay device 101 receives a CAN frame from the in-vehicle ECU 202 or another in-vehicle relay device 101. Here, the in-vehicle relay device 101 receives a CAN frame including a CAN-ID registered in the reception list L in the storage unit 13 (step S101).

[0111] Next, the in-vehicle relay device 101 stores the received CAN frame in the storage unit 13 (step S102).

[0112] Next, the in-vehicle relay device 101 performs a determination process D1 to determine whether the received CAN frame is a frame to be compressed. For example, as described above, the in-vehicle relay device 101 refers to the reception list L in the storage unit 13 to check whether the discrimination flag of the CAN-ID included in the CAN frame stored in the storage unit 13 is "1" (step S103).

[0113] And when the discrimination flag of the CAN-ID included in the CAN frame stored in the storage unit 13 is "1", that is, when the CAN frame is a frame to be compressed (YES in step S104), until a predetermined time elapses, that is, until the time of the calculation period T elapses (NO in step S105), the in-vehicle relay device 101 performs reception of the CAN frame, storage of the CAN frame, and the determination process D1 (steps S101 to S103).

[0114] Next, when the time of the calculation period T elapses (YES in step S105), the in-vehicle relay device 101 refers to the routing table Tb11 in the storage unit 13 to specify the destination bus corresponding to the CAN-ID included in each CAN frame stored in the storage unit 13. Here, it is assumed that the specified destination bus is one (step S106).

[0115] Next, the in-vehicle relay device 101 calculates an estimated value of the bus load on the specified destination bus (step S107).

[0116] Next, when the estimated value of the bus load calculated by the in-vehicle relay device 101 is equal to or greater than the threshold Th (YES in step S108), compression processing is performed. For example, as described above, the in-vehicle relay device 101 compresses the CAN frame, which is the frame to be compressed, according to the compression method C (step S109).

[0117] Next, the in-vehicle relay device 101 creates a frame F1 in which the compressed CAN frame is stored in the DAT field. Then, the in-vehicle relay device 101 stores the compression processing ID in the ID field of the created frame F1 (step S110).

[0118] Next, the in-vehicle relay device 101 outputs the frame F1 to the specified destination bus (step S111).

[0119] On the other hand, when the estimated value of the bus load calculated by the in-vehicle relay device 101 is less than the threshold Th (NO in step S108), the in-vehicle relay device 101 does not perform compression processing and outputs the CAN frame stored in the storage unit 13 to the specified destination bus (step S112).

[0120] In addition, when the received CAN frame is not a frame to be compressed (NO in step S103), the in-vehicle relay device 101 performs a determination process D2 to determine whether the CAN frame is a frame to be decompressed. For example, as described above, the in-vehicle relay device 101 checks whether the CAN-ID included in the CAN frame is a decompression target ID (step S113).

[0121] Next, when the received CAN frame is a frame to be decompressed (YES in step S114), the in-vehicle relay device 101 performs a decompression process to decompress the compressed CAN frame stored in the DAT field of the CAN frame. Then, the in-vehicle relay device 101 discards the frame to be decompressed (step S115).

[0122] Next, the in-vehicle relay device 101 outputs the CAN frame after the extension process to the destination bus. For example, as described above, the in-vehicle relay device 101 refers to the routing table Tb11 in the storage unit 13 to identify the destination bus corresponding to the CAN-ID included in the CAN frame after the extension process, and outputs the CAN frame after the extension process to the identified destination bus (step S116).

[0123] On the other hand, when the received CAN frame is neither a compression target frame nor an extension target frame (NO in step S103 and NO in step S114), the in-vehicle relay device 101 outputs the received CAN frame to the destination bus. For example, as described above, the in-vehicle relay device 101 refers to the routing table Tb11 in the storage unit 13 to identify the destination bus corresponding to the CAN-ID included in the received CAN frame, and outputs the CAN frame to the identified destination bus (step S117).

[0124] Note that in the flowcharts shown in FIGS. 9 and 10, the in-vehicle relay device 101 is not limited to a configuration that performs both the compression process and the extension process, and may be a configuration that performs only one of the compression process and the extension process.

[0125] Also, in the in-vehicle communication system 301 according to the first embodiment of the present disclosure, it is assumed that the in-vehicle relay device 101A performs the compression process and the in-vehicle relay device 101B performs the extension process on the CAN frame after the compression process received from the in-vehicle relay device 101A. However, the present disclosure is not limited to this. The in-vehicle relay device 101B may perform the compression process, and the in-vehicle relay device 101A may perform the extension process on the CAN frame after the compression process received from the in-vehicle relay device 101B.

[0126] Also, in the in-vehicle communication system 301 according to the first embodiment of the present disclosure, although the in-vehicle relay device 101A performs the discrimination process D1 to discriminate the frames to be compressed from the received frames, and the in-vehicle relay device 101B performs the discrimination process D2 to discriminate the frames to be decompressed from the received frames, the present disclosure is not limited thereto. The in-vehicle relay device 101A may be configured not to perform the discrimination process D1 and to compress all CAN frames whose destination bus is the CAN bus 51B. In this case, the in-vehicle relay device 101B does not perform the discrimination process D2 and decompresses all CAN frames whose source bus is the CAN bus 51B.

[0127] Also, in the in-vehicle communication system 301 according to the first embodiment of the present disclosure, although the in-vehicle relay device 101 performs the discrimination process D1 by checking whether the CAN-ID included in the received CAN frame is the ID to be compressed, the present disclosure is not limited thereto. The in-vehicle relay device 101 may be configured to perform the discrimination process D1 using other information stored in the CAN frame other than the CAN-ID.

[0128] Also, in the in-vehicle communication system 301 according to the first embodiment of the present disclosure, although the in-vehicle relay device 101 performs the discrimination process D2 by checking whether the CAN-ID included in the received CAN frame is the ID to be decompressed, the present disclosure is not limited thereto. The in-vehicle relay device 101 may be configured to perform the discrimination process D2 using other information stored in the CAN frame other than the CAN-ID.

[0129] Also, in the in-vehicle communication system 301 according to the first embodiment of the present disclosure, although the in-vehicle relay device 101 is configured not to perform the compression process of the operation frames, the present disclosure is not limited thereto. The in-vehicle relay device 101 may be configured to perform the compression process of the operation frames.

[0130] Also, in the in-vehicle communication system 301 according to the first embodiment of the present disclosure, although the in-vehicle relay device 101A is configured to transmit a CAN frame with a specific CAN-ID for compression processing, that is, a frame F1 in which the compression processing ID is stored in the ID field, to the in-vehicle relay device 101B, the present disclosure is not limited thereto. The in-vehicle relay device 101A may be configured to transmit a frame F1 in which specific information for compression processing is stored in a field other than the ID field to the in-vehicle relay device 101B.

[0131] Also, in the in-vehicle communication system 301 according to the first embodiment of the present disclosure, although the in-vehicle relay device 101 is configured to determine whether to perform compression processing according to the estimated result of the bus load on the CAN bus 51 of the relay destination of the CAN frame, the present disclosure is not limited thereto. The in-vehicle relay device 101 may be configured to perform compression processing regardless of the estimated result. Also, the in-vehicle relay device 101 may be configured to determine whether to perform compression processing according to the number of in-vehicle ECUs 202 connected to itself. In this case, for example, the in-vehicle relay device 101 determines to perform compression processing when the number of in-vehicle ECUs 202 connected to itself is equal to or greater than a predetermined threshold.

[0132] Next, other embodiments of the present disclosure will be described with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and their description will not be repeated.

[0133] <Second Embodiment> In the first embodiment of the present disclosure described above, the in-vehicle communication system 301 includes two in-vehicle relay devices 101. In contrast, in the second embodiment of the present disclosure, the in-vehicle communication system 302 includes three or more in-vehicle relay devices 101. Except for the content described below, it is the same as the in-vehicle communication system 301 according to the first embodiment.

[0134] FIG. 11 is a diagram showing the configuration of an in-vehicle communication system according to a second embodiment of the present disclosure. Referring to FIG. 11, for example, the in-vehicle communication system 302 includes three or more in-vehicle relay devices 101. Specifically, for example, the in-vehicle communication system 302 further includes in-vehicle relay devices 101C and 101D, which are in-vehicle relay devices 101, as compared with the in-vehicle communication system 301 shown in FIG. 1. The in-vehicle relay device 101D is an example of a third in-vehicle relay device.

[0135] In the example shown in FIG. 11, the in-vehicle relay device 101C is connected to the in-vehicle relay device 101A via the CAN bus 51B. The in-vehicle relay device 101D is connected to the in-vehicle relay device 101A via the CAN bus 51C.

[0136] Further, the in-vehicle communication system 302 further includes in-vehicle ECUs 202J, 202K, 202L, and 202M, which are in-vehicle ECUs 202, as compared with the in-vehicle communication system 301 shown in FIG. 1.

[0137] In the example shown in FIG. 11, the in-vehicle ECUs 202J and 202K are connected to the in-vehicle relay device 101C via the CAN bus 51E, which is the CAN bus 51. The in-vehicle ECUs 202L and 202M are connected to the in-vehicle relay device 101D via the CAN bus 51F, which is the CAN bus 51.

[0138] In the present embodiment, for example, the in-vehicle ECU 202A is an integrated ECU, and the in-vehicle ECUs 202 other than the in-vehicle ECU 202A are individual ECUs.

[0139] Detection devices and actuators (not shown) are connected to the individual ECUs. The detection devices are, for example, various sensors. The individual ECU transmits the detection data received from the detection devices connected to itself to the integrated ECU.

[0140] The integrated ECU generates control information for driving an actuator, for example, based on detection data received from individual ECUs. Then, the individual ECU transmits the generated control information to the individual ECU that is the source of the detection data or to an individual ECU different from the individual ECU that is the source of the detection data.

[0141] The individual ECU drives the actuator connected to itself based on the control information received from the integrated ECU.

[0142] FIG. 12 is a diagram showing an example of a CAN table stored in the in-vehicle relay device according to the second embodiment of the present disclosure. FIG. 12 shows the CAN table Tb22 stored in the in-vehicle relay devices 101A, 101B, and 101C.

[0143] In the CAN table Tb22 shown in FIG. 12, compared with the CAN table Tb12 shown in FIG. 7, the source "in-vehicle relay device 101A" and the destination "in-vehicle relay device 101C" of a CAN frame that includes the CAN-ID "0x101" and whose information type is "for compression processing" are added.

[0144] Referring to FIG. 3 again, in the in-vehicle relay device 101A, when the compression processing unit 22 transmits the frame F1 shown in FIG. 6 to the in-vehicle relay device 101C via the CAN bus 51B, by referring to the CAN table Tb22 in the storage unit 13, it is confirmed that the source and destination are the in-vehicle relay device 101A and the in-vehicle relay device 101C, respectively, and the CAN-ID corresponding to the CAN frame whose information type is "for compression processing" is "0x101".

[0145] Then, the compression processing unit 22 transmits the frame F1 with the CAN-ID "0x101" stored in the ID field to the in-vehicle relay device 101C via the relay unit 11.

[0146] [In-vehicle relay device 101C] The in-vehicle relay device 101C performs a discrimination process D2 to discriminate the extended target frame of the in-vehicle relay device 101C from the received CAN frames.

[0147] More specifically, for example, in in-vehicle relay device 101C, discrimination unit 21 performs discrimination process D2 using the ID to be extended. In the present embodiment, for example, the ID to be extended of in-vehicle relay device 101C is the CAN-ID "0x101" corresponding to the destination of the CAN frame, "in-vehicle relay device 101C", and the information type, "for compression process", registered in CAN table Tb22 shown in FIG. 12.

[0148] For example, when discrimination unit 21 receives ID information E1 from relay unit 11, it checks whether the CAN-ID indicated by the ID information E1 is the same as the ID to be extended, "0x101", by referring to CAN table Tb22 in storage unit 13.

[0149] When the CAN-ID indicated by the ID information E1 received by discrimination unit 21 from relay unit 11 is the same as the ID to be extended, "0x101", discrimination unit 21 recognizes that the CAN frame including the CAN-ID is the frame to be extended by in-vehicle relay device 101C. Then, discrimination unit 21 outputs the ID information E1 received from relay unit 11 to extension processing unit 23.

[0150] As described above, in the present embodiment, in the ID field of frame F1 transmitted from in-vehicle relay device 101A, the compression process ID "0x101" is stored. The compression process ID "0x101" is the same as the ID to be extended by in-vehicle relay device 101C registered in CAN table Tb22, that is, the CAN-ID corresponding to the destination of the CAN frame, "in-vehicle relay device 101C", and the information type, "for compression process". Therefore, discrimination unit 21 in in-vehicle relay device 101C recognizes that frame F1 is the frame to be extended by in-vehicle relay device 101C.

[0151] On the other hand, when the CAN-ID indicated by the ID information E1 received by discrimination unit 21 from relay unit 11 is different from the ID to be extended, "0x101", discrimination unit 21 recognizes that the CAN frame including the CAN-ID is not the frame to be extended by in-vehicle relay device 101C. Then, discrimination unit 21 outputs the ID information E1 to relay unit 11.

[0152] Referring to FIGS. 3 and 5, when the relay unit 11 receives the ID information E1 from the discrimination unit 21, it refers to the routing table Tb11 in the storage unit 13 to identify the destination bus corresponding to the CAN-ID indicated by the ID information E1. Then, the relay unit 11 acquires the CAN frame including the CAN-ID from the storage unit 13 and outputs the acquired CAN frame to the identified destination bus.

[0153] [In-vehicle relay device 101D] In the in-vehicle communication system 302, the bus load of the CAN bus 51C is smaller than the bus loads of the other CAN buses 51. In this case, for example, the in-vehicle relay device 101D connected to the CAN bus 51C does not perform compression processing and decompression processing.

[0154] More specifically, for example, when the in-vehicle relay device 101D receives a CAN frame having the CAN bus 51C as the destination bus from the in-vehicle ECU 202L or the in-vehicle ECU 202M connected to itself, it performs relay processing on the received CAN frame without compressing it.

[0155] Also, for example, in the in-vehicle relay device 101A, in the CAN table Tb22 in the storage unit 13, the CAN-ID corresponding to the CAN frame whose source and destination are the in-vehicle relay device 101A and the in-vehicle relay device 101D, respectively, and the information type is "for compression processing" is not registered. That is, the in-vehicle relay device 101A does not transmit the frame F1 to the in-vehicle relay device 101D via the CAN bus 51C. Also, the in-vehicle relay device 101D does not perform decompression processing.

[0156] Since the other configurations and operations are the same as those of the in-vehicle communication system 301 according to the first embodiment, detailed description is not repeated here.

[0157] The above-described embodiments should be considered as illustrative in all respects and not restrictive. The scope of the present invention is shown by the scope of claims rather than the above description, and it is intended that all modifications within the meaning and scope equivalent to the scope of claims be included.

[0158] Each process (each function) of the above-described embodiment is realized by a processing circuit including one or more processors. The processing circuit may be composed of, in addition to the one or more processors, an integrated circuit in which one or more memories, various analog circuits, and various digital circuits are combined. The one or more memories store a program (instruction) for causing the one or more processors to execute each of the above processes. The one or more processors may execute each of the above processes according to the program read from the one or more memories, or may execute each of the above processes according to a logic circuit designed in advance to execute each of the above processes. The processor may be various processors suitable for computer control, such as a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), a DSP (Digital Signal Processor), an FPGA (Field Programmable Gate Array), and an ASIC (Application Specific Integrated Circuit). Note that the plurality of physically separated processors may cooperate with each other to execute each of the above processes. For example, the processors mounted on each of a plurality of physically separated computers may cooperate with each other via a network such as a LAN (Local Area Network), a WAN (Wide Area Network), and the Internet to execute each of the above processes. The program may be installed in the memory via the network from an external server device or the like, or may be distributed in a state stored in a recording medium such as a CD-ROM (Compact Disc Read Only Memory), a DVD-ROM (Digital Versatile Disk Read Only Memory), and a semiconductor memory, and may be installed in the memory from the recording medium.

[0159] The above description includes the features appended below. [Appendix 1] A relay method in a vehicle-mounted communication system including a plurality of vehicle-mounted devices and a plurality of vehicle-mounted relay devices, comprising: The plurality of in-vehicle relay devices includes a first in-vehicle relay device and a second in-vehicle relay device connected to the first in-vehicle relay device via a communication bus, the in-vehicle relay device performs a relay process of relaying frames transmitted and received between the in-vehicle devices, a step in which the first in-vehicle relay device performs a compression process of compressing the frame and transmits the compressed frame to the second in-vehicle relay device via the communication bus; a step in which the second in-vehicle relay device performs an expansion process of expanding the compressed frame received from the first in-vehicle relay device and performs the relay process on the expanded frame. A relay method.

[0160] [Appendix 2] A relay program used in an in-vehicle communication system including a plurality of in-vehicle devices and performing a relay process of relaying frames transmitted and received between the in-vehicle devices, in an in-vehicle relay device, the in-vehicle relay device is connected to other in-vehicle relay devices via a CAN bus, a computer, a relay unit that receives the frame, a compression processing unit that performs a compression process of compressing the frame received by the relay unit, a program for functioning as, the relay unit transmits the compressed frame by the compression processing unit to the other in-vehicle relay devices via the communication bus. A relay program.

[0161] [Appendix 3] An in-vehicle relay device used in an in-vehicle communication system including a plurality of in-vehicle devices and performing a relay process of relaying frames transmitted and received between the in-vehicle devices, the in-vehicle relay device is connected to other in-vehicle relay devices via a CAN bus, equipped with a processing circuit, the processing circuit, receives the frame, Perform a compression process to compress the received frame, An in-vehicle relay device that transmits the frame after the compression process to the other in-vehicle relay device via the communication bus.

Explanation of Signs

[0162] 1 Vehicle 11 Relay section 12 Processing section 13 Storage section 21 Discrimination section 22 Compression processing section 23 Decompression processing section 24 Monitoring section 51, 51A, 51B, 51C, 51D, 51E, 51F CAN bus 101, 101A, 101B, 101C, 101D In-vehicle relay device 202 In-vehicle ECU 301, 302 In-vehicle communication system 401 In-vehicle network L Reception list Tb11 Routing table Tb21, Tb22 CAN table

Claims

1. A plurality of in-vehicle devices, a first in-vehicle relay device, and a plurality of in-vehicle relay devices including a second in-vehicle relay device connected to the first in-vehicle relay device via a communication bus, wherein the in-vehicle relay device performs a relay process of relaying frames transmitted and received between the in-vehicle devices, the first in-vehicle relay device performs a compression process of compressing the frame, and transmits the compressed frame to the second in-vehicle relay device via the communication bus, and the second in-vehicle relay device performs an expansion process of expanding the compressed frame received from the first in-vehicle relay device, and performs the relay process of the expanded frame. An in-vehicle communication system.

2. The first in-vehicle relay device performs a first discrimination process of discriminating a compression target frame, which is the frame to be compressed, from the received frames, and performs the compression process on the discriminated compression target frame, and the second in-vehicle relay device performs a second discrimination process of discriminating an expansion target frame, which is the frame to be expanded, from the received frames, and performs the expansion process on the discriminated expansion target frame. The in-vehicle communication system according to claim 1.

3. The first in-vehicle relay device holds first identification information corresponding to the compression target frame, and performs the first discrimination process using the held first identification information, and the second in-vehicle relay device holds second identification information corresponding to the expansion target frame, and performs the second discrimination process using the held second identification information. The in-vehicle communication system according to claim 2.

4. The first in-vehicle relay device does not perform the compression process on an operation frame, which is the frame related to the operation of the vehicle on which the in-vehicle communication system is mounted. The in-vehicle communication system according to any one of claims 1 to 3.

5. The first in-vehicle relay device receives the frame conforming to the CAN standard, and the first in-vehicle relay device transmits the compressed frame with a specific CAN-ID for compression processing to the second in-vehicle relay device via the communication bus. The in-vehicle communication system according to claim 1 or claim 2.

6. The first in-vehicle relay device determines whether to perform the compression process based on an estimated result of the communication load on the communication bus. The in-vehicle communication system according to claim 1 or claim 2.

7. The in-vehicle communication system includes three or more of the in-vehicle relay devices. The third in-vehicle relay device does not perform the compression process and the decompression process. The in-vehicle communication system according to claim 1 or claim 2.

8. An in-vehicle relay device that is used in an in-vehicle communication system including a plurality of in-vehicle devices and performs a relay process for relaying frames transmitted and received between the in-vehicle devices, The in-vehicle relay device is connected to other in-vehicle relay devices via a communication bus. A relay unit that receives the frame, A compression processing unit that performs a compression process of compressing the frame received by the relay unit, The relay unit transmits the frame after the compression process by the compression processing unit to the other in-vehicle relay devices via the communication bus. The in-vehicle relay device.

9. The relay unit further receives the frame after the compression process transmitted from the other in-vehicle relay device, The in-vehicle relay device further includes a decompression processing unit that performs a decompression process of decompressing the frame after the compression process received by the relay unit, The relay unit performs the relay process of the frame after the decompression process by the decompression processing unit. The in-vehicle relay device according to claim 8.

10. A relay method in an in-vehicle relay device that is used in an in-vehicle communication system including a plurality of in-vehicle devices and performs a relay process for relaying frames transmitted and received between the in-vehicle devices, The in-vehicle relay device is connected to other in-vehicle relay devices via a communication bus. Receiving the frame, Performing a compression process of compressing the received frame, And transmitting the frame after the compression process to the other in-vehicle relay devices via the communication bus. The relay method.

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