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

Abstract

This on-vehicle communication system comprises: 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 to the first on-vehicle relay device via a communication bus. The on-vehicle relay devices perform relay processing for relaying frames transmitted and received between the on-vehicle devices. The first on-vehicle relay device performs compression processing for compressing the frames, and transmits the compressed frame to the second on-vehicle relay device via the communication bus. The second on-vehicle relay device performs decompression processing for decompressing the compressed frame received from the first on-vehicle relay device, and performs the relay processing of the decompressed frame.

Description

Vehicle-mounted communication system, vehicle-mounted relay device, and relay method

[0001] This application claims priority based on Japanese Patent Application No. 2023-197797, filed November 22, 2023, the disclosure of which is incorporated herein by reference in its entirety.

[0002] Patent Document 1 (Japanese Patent Laid-Open Publication No. 2006-287738) discloses the following network system: In this network system, at least one of the destinations is a gateway node connected to a CAN bus network, and the gateway node is equipped with bus load monitoring means that monitors frames sent to the CAN bus and monitors the bus load state on the CAN bus.

[0003] Japanese Patent Application Laid-Open No. 2006-287738

[0004] The in-vehicle communication system of the present disclosure comprises a plurality of in-vehicle devices, 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, wherein the in-vehicle relay device performs a relay process to relay frames transmitted and received between the in-vehicle devices, the first in-vehicle relay device performs a compression process to compress the frames and transmits the frames after the compression process to the second in-vehicle relay device via the communication bus, and the second in-vehicle relay device performs an expansion process to expand the frames after the compression process received from the first in-vehicle relay device and performs the relay process of the frames after the expansion process.

[0005] One aspect of the present disclosure may be realized not only as an in-vehicle communication system including such a characteristic processing unit, but also as a method having such characteristic processing steps, or as a program for causing a computer to execute such steps. Furthermore, one aspect of the present disclosure may be realized as a semiconductor integrated circuit that realizes part or all of the in-vehicle communication system.

[0006] One aspect of the present disclosure may be realized not only as an in-vehicle relay device having such a characteristic processing unit, but also as a program for causing a computer to execute the steps of such a characteristic processing, or as a semiconductor integrated circuit that realizes part or all of the in-vehicle relay device.

[0007] FIG. 1 is a diagram illustrating a configuration of an in-vehicle communication system according to a first embodiment of the present disclosure. FIG. 2 is a diagram illustrating an example of a CAN frame transmitted by an in-vehicle ECU in the in-vehicle communication system according to the first embodiment of the present disclosure. FIG. 3 is a diagram illustrating a configuration of an in-vehicle relay device according to the first embodiment of the present disclosure. FIG. 4 is a diagram illustrating an example of a reception list stored by the in-vehicle relay device according to the first embodiment of the present disclosure. FIG. 5 is a diagram illustrating an example of a routing table stored by the in-vehicle relay device according to the first embodiment of the present disclosure. FIG. 6 is a diagram illustrating an example of a CAN frame created by the in-vehicle relay device according to the first embodiment of the present disclosure. FIG. 7 is a diagram illustrating an example of a CAN table stored by the in-vehicle relay device according to the first embodiment of the present disclosure. FIG. 8 is a time chart illustrating an example of compression processing and decompression processing by the in-vehicle relay device according to the first embodiment of the present disclosure. FIG. 9 is a flowchart defining an operation procedure when the in-vehicle relay device according to the first embodiment of the present disclosure performs compression processing and decompression processing. Fig. 10 is a flowchart defining an operation procedure when an in-vehicle relay device according to a first embodiment of the present disclosure performs compression processing and decompression processing. Fig. 11 is a diagram illustrating a configuration of an in-vehicle communication system according to a second embodiment of the present disclosure. Fig. 12 is a diagram illustrating an example of a CAN table stored in an in-vehicle relay device according to the second embodiment of the present disclosure.

[0008] 2. Description of the Related Art Conventionally, a technique has been developed for monitoring the bus load on a communication bus to which a frame is relayed in an on-board relay device that relays frames transmitted and received between on-board devices.

[0009] [Problem to be Solved by the Present Disclosure] In recent years, there has been a trend toward an increase in the number of types of services executed in in-vehicle networks, which may increase the bus load in the in-vehicle network.

[0010] In the network system described in Patent Document 1, when the bus load is large, processing is performed to reduce the data length of the frame to be relayed, processing is performed to stop the relay processing of the frame, etc. However, when such processing is performed, there is a possibility that data that should be acquired by the in-vehicle device at the frame destination will be deleted, or that the frame will not be relayed.

[0011] The present disclosure has been made to solve the above-mentioned problems, and its purpose is to provide an in-vehicle communication system, an in-vehicle relay device, and a relay method that can reduce bus load while suppressing the impact on frame relay processing in an in-vehicle network.

[0012] Effect of the Present Disclosure According to the present disclosure, it is possible to reduce the bus load while suppressing the impact on the frame relay process in an in-vehicle network.

[0013] [Description of Embodiments of the Present Disclosure] First, the contents of the embodiments of the present disclosure will be listed and described. (1) An in-vehicle communication system according to an embodiment of the present disclosure includes a plurality of in-vehicle devices, 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 to relay frames transmitted and received between the in-vehicle devices, the first in-vehicle relay device performs a compression process to compress the frames and transmits the compressed frames to the second in-vehicle relay device via the communication bus, the second in-vehicle relay device performs a decompression process to decompress the compressed frames received from the first in-vehicle relay device, and performs the relay process of the decompressed frames.

[0014] In this way, the first in-vehicle relay device is configured to compress the frame to be relayed and output it to the relay destination bus, thereby reducing the communication load on the bus without requiring the relay process to be stopped or the frame data to be reduced. Therefore, the bus load can be reduced while minimizing the impact on the frame relay process in the in-vehicle network. Furthermore, the second in-vehicle relay device is configured to decompress the frame compressed by the first in-vehicle relay device and relay the decompressed frame, thereby eliminating the need for decompression processing in the in-vehicle device at the frame's destination, thereby reducing the processing load on the in-vehicle device.

[0015] (2) In (1) above, the first vehicle-mounted relay device may perform a first discrimination process to determine from the received frames which frames are compression target frames, which are frames that are the target of the compression process, and perform the compression process on the determined compression target frames, and the second vehicle-mounted relay device may perform a second discrimination process to determine from the received frames which frames are decompression target frames, which are frames that are the target of the decompression process, and perform the decompression process on the determined decompression target frames.

[0016] With this configuration, compression processing and decompression processing can be selectively performed, so that the in-vehicle communication system as a whole can efficiently transmit frames.

[0017] (3) In (2) above, the first vehicle-mounted relay device may hold first identification information corresponding to the frame to be compressed and perform the first determination process using the first identification information it holds, and the second vehicle-mounted relay device may hold second identification information corresponding to the frame to be decompressed and perform the second determination process using the second identification information it holds.

[0018] With this configuration, the first vehicle-mounted relay device can more accurately determine frames to be compressed through simple processing, and the second vehicle-mounted relay device can more accurately determine frames to be decompressed through simple processing.

[0019] (4) In any of (1) to (3) above, the first vehicle-mounted relay device may not perform the compression process on driving frames, which are frames related to driving of a vehicle in which the vehicle-mounted communication system is installed.

[0020] For example, since the allowable delay time for frames related to vehicle driving is short, by outputting the frames to the destination bus without compressing them, it is possible to prevent the frames from being transmitted beyond the allowable delay time.

[0021] (5) In any of (1) to (4) above, the first vehicle-mounted relay device may receive the frame conforming to the CAN standard, and the first vehicle-mounted relay device may transmit the frame after the compression process, with a specific CAN-ID for the compression process attached, to the second vehicle-mounted relay device via the communication bus.

[0022] With this configuration, it is possible to easily recognize that the received frame is a compressed frame.

[0023] (6) In any one of (1) to (5) above, the first vehicle-mounted relay device may determine whether to perform the compression process based on an estimated communication load on the communication bus.

[0024] With this configuration, for example, when a situation where the communication load on the relay destination bus is expected to be large is anticipated, the communication load on the bus can be more reliably reduced by performing compression processing. Furthermore, since the number of times compression processing is performed can be reduced according to the communication load, the processing load on the first vehicle-mounted relay device can be reduced.

[0025] (7) In any of (1) to (6) above, the in-vehicle communication system may include three or more in-vehicle relay devices, and the third in-vehicle relay device may not perform the compression processing and the decompression processing.

[0026] For example, in a configuration in which an in-vehicle communication system includes three or more in-vehicle relay devices, the communication load of a communication bus to which one of the three or more in-vehicle relay devices is connected may be smaller than the communication load of a communication bus to which another in-vehicle relay device is connected. With the above configuration, when it is not necessary to reduce the communication load of a certain communication bus, the processing load of the in-vehicle relay device can be reduced by not performing compression and decompression processing in the in-vehicle relay device connected to that communication bus. Furthermore, by performing compression processing in the in-vehicle relay device connected to the communication bus whose communication load needs to be reduced, the bus load of the entire in-vehicle communication system can be efficiently reduced.

[0027] (8) An in-vehicle relay device according to an embodiment of the present disclosure is used in an in-vehicle communication system having a plurality of in-vehicle devices, and is an in-vehicle relay device that performs relay processing to relay frames transmitted and received between the in-vehicle devices, wherein the in-vehicle relay device is connected to other in-vehicle relay devices via a communication bus, and is equipped with a relay unit that receives the frames, and a compression processing unit that performs compression processing to compress the frames received by the relay unit, and the relay unit transmits the frames after the compression processing by the compression processing unit to the other in-vehicle relay devices via the communication bus.

[0028] In this way, by compressing the frames to be relayed and outputting them to the bus at the relay destination, it is possible to reduce the communication load on the bus without stopping the relay process or reducing the frame data, thereby reducing the bus load while suppressing the impact on the frame relay process in the in-vehicle network.

[0029] (9) In the above (8), the relay unit may further receive the frame after the compression processing transmitted from the other vehicle-mounted relay device, and the vehicle-mounted relay device may further include an expansion processing unit that performs an expansion processing to expand the frame after the compression processing received by the relay unit, and the relay unit may perform the relay processing of the frame after the expansion processing by the expansion processing unit.

[0030] With this configuration, compressed frames can be transmitted in both directions on a communication bus connecting multiple vehicle-mounted relay devices, thereby further reducing the communication load on the communication bus.

[0031] (10) A relay method according to an embodiment of the present disclosure is used in an in-vehicle communication system having a plurality of in-vehicle devices, and is a relay method in an in-vehicle relay device that performs relay processing to relay frames transmitted and received between the in-vehicle devices, wherein 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 processing to compress the received frame, and a step of transmitting the frame after the compression processing to the other in-vehicle relay device via the communication bus.

[0032] In this way, by compressing the frames to be relayed and outputting them to the bus at the relay destination, it is possible to reduce the communication load on the bus without stopping the relay process or reducing the frame data, thereby reducing the bus load while suppressing the impact on the frame relay process in the in-vehicle network.

[0033] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the drawings, identical or corresponding parts are designated by the same reference numerals, and their description will not be repeated. Furthermore, at least some of the embodiments described below may be combined in any manner.

[0034] <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 the 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 ECUs 202 are an example of an in-vehicle device.

[0035] 1 , the in-vehicle communication system 301 includes in-vehicle relay devices 101A and 101B that are in-vehicle relay devices 101, and in-vehicle ECUs 202A, 202B, 202C, 202D, 202E, 202F, and 202G that 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.

[0036] The in-vehicle communication system 301 is not limited to a configuration including seven in-vehicle ECUs 202, but may be a configuration including two to six or eight or more in-vehicle ECUs 202.

[0037] The in-vehicle ECU 202 is a TCU (Telematics Communication Unit), an engine ECU, an automatic driving ECU, a brake control ECU, an airbag control ECU, a door lock ECU, etc. In addition to the in-vehicle ECU 202 or instead of the in-vehicle ECU 202, the in-vehicle communication system 301 may include in-vehicle devices such as a sensor, a navigation device, a human-machine interface, and a camera.

[0038] The multiple in-vehicle relay devices 101 and the multiple in-vehicle ECUs 202 configure an in-vehicle network 401. The multiple in-vehicle ECUs 202 are connected to the in-vehicle relay device 101 via a CAN bus 51 that complies with the CAN (Controller Area Network) standard, for example. The CAN bus 51 is an example of a communication bus.

[0039] 1 , in-vehicle ECUs 202A, 202B, and 202C are connected to in-vehicle relay device 101A via CAN bus 51A, which is also CAN bus 51. In-vehicle ECU 202F is connected to in-vehicle relay device 101A and in-vehicle relay device 101B via CAN bus 51B, which is also CAN bus 51. In-vehicle ECU 202G is connected to in-vehicle relay device 101A via CAN bus 51C, which is also CAN bus 51. In-vehicle ECUs 202D and 202E are connected to in-vehicle relay device 101B via CAN bus 51D, which is also CAN bus 51.

[0040] The in-vehicle relay device 101 relays frames transmitted and received between a plurality of in-vehicle ECUs 202 connected thereto.

[0041] The in-vehicle relay device 101B is connected to the in-vehicle relay device 101A via a CAN bus 51B.

[0042] Hereinafter, CAN bus 51A will also be referred to as "CAN1," CAN bus 51B as "CAN2," CAN bus 51C as "CAN3," and CAN bus 51D as "CAN4."

[0043] 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 .

[0044] Specifically, for example, each on-board ECU 202 transmits a CAN frame to another on-board ECU 202 or on-board relay device 101, the CAN frame including various information such as information to assist the automatic driving performed by the vehicle 1 and information used for entertainment, and a CAN-ID (Identifier) ​​indicating the type of data, etc.

[0045] 2 is a diagram illustrating an example of a CAN frame transmitted by an on-board ECU in the on-board communication system according to the first embodiment of the present disclosure. Referring to Fig. 2, the CAN frame includes, in this order from the beginning of the frame, a start of frame (SOF) field, an ID field, a remote transmission request (RTR) field, a control field, a data field (hereinafter also referred to as a DAT field), a cyclic redundancy check (CRC) field, an ACK field, and an end of frame (EOF) field.

[0046] 3 is a diagram illustrating a configuration of an in-vehicle relay device according to a 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, an expansion processing unit 23, and a monitoring unit 24. One or both of the relay unit 11 and the processing unit 12 are realized, for example, by a processing circuit including one or more processors. The storage unit 13 is, for example, a non-volatile memory included in the processing circuit.

[0047] 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 should be received by its own in-vehicle relay device 101.

[0048] Fig. 4 is a diagram showing an example of a receiving list L stored by the vehicle-mounted relay device according to the first embodiment of the present disclosure. Fig. 4 shows an example of a receiving list L stored by the vehicle-mounted relay device 101A.

[0049] 3 and 4, the storage unit 13 stores, for example, a reception list L indicating the CAN-IDs included in the CAN frames that should be received by the vehicle-mounted relay device 101A. The reception list L is registered in the storage unit 13 by the manufacturer of the vehicle 1, for example, when the vehicle 1 is shipped.

[0050] In the reception list L shown in FIG. 4, the CAN-ID included in the CAN frame to be received by the vehicle-mounted relay device 101A is "0x000", "0x001", "0x002", "0x003", "0x004", or "0x100".

[0051] When the relay unit 11 receives a CAN frame, it refers to the reception list L in the storage unit 13 to check whether the CAN-ID included in the CAN frame is registered in the reception list L.

[0052] For example, if the CAN-ID included in a received CAN frame is not registered in the reception list L, the relay unit 11 discards the CAN frame. On the other hand, if the CAN-ID included in a received CAN frame is registered in the reception list L, 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.

[0053] [Compression Processing] The compression processing unit 22 performs compression processing to compress the CAN frame received by the relay unit 11 .

[0054] More specifically, for example, the storage unit 13 stores a CAN-ID (hereinafter also referred to as a “compression target ID”) corresponding to a CAN frame to be compressed (hereinafter also referred to as a “compression target frame”). The compression target ID is an example of first identification information.

[0055] 4 further includes a determination flag. The determination flag indicates whether a CAN-ID registered in the reception list L is a compression target ID.

[0056] In the receiving list L, a discrimination flag of "1" indicates that the CAN-ID registered in the receiving list L is an ID to be compressed. A discrimination flag of "0" indicates that the CAN-ID is not an ID to be compressed.

[0057] For example, the compression processing unit 22 does not perform compression processing on CAN frames (hereinafter also referred to as "driving frames") related to driving of the vehicle 1. For example, a driving frame is a CAN frame that includes information for controlling the brakes of the vehicle 1 or information for controlling the airbags of the vehicle 1. In the reception list L, the discrimination flag corresponding to the CAN-ID included in the driving frame is set to "0".

[0058] 4, for example, the discrimination flag for CAN-ID "0x000," "0x001," or "0x003" is "1." The discrimination flag for CAN-ID "0x002" or "0x100" is "0."

[0059] 3, the discrimination unit 21 performs discrimination process D1 to discriminate frames to be compressed from among the CAN frames received by the relay unit 11. The discrimination process D1 is an example of a first discrimination process.

[0060] More specifically, for example, the discriminator 21 performs a discrimination process D1 using the compression target ID. For example, every time the discriminator 21 receives ID information E1 from the relay unit 11, the discriminator 21 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."

[0061] If the discrimination flag of the CAN-ID indicated by the ID information E1 received 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 frame to be compressed. Then, the discrimination unit 21 outputs the ID information E1 to the relay unit 11.

[0062] FIG. 5 is a diagram illustrating an example of a routing table stored by the vehicle-mounted relay device according to the first embodiment of the present disclosure.

[0063] 5, storage unit 13 stores a routing table Tb11 indicating the correspondence between a CAN-ID, a CAN bus 51 to which a source of a CAN frame is connected (hereinafter also referred to as a "source bus"), and a CAN bus 51 to which a destination of the CAN frame is connected (hereinafter also referred to as a "destination bus"). Routing table Tb11 is registered in storage unit 13 by the manufacturer of vehicle 1, for example, when vehicle 1 is shipped.

[0064] In the routing table Tb11 shown in FIG. 5, the source bus of a CAN frame containing a CAN-ID of "0x000," "0x001," or "0x002" is "CAN1," and the destination bus of the CAN frame is "CAN2." The source bus of a CAN frame containing a CAN-ID of "0x003" is "CAN1," and the destination bus of the CAN frame is "CAN3." The source bus of a CAN frame containing a CAN-ID of "0x004" is "CAN4," and the destination bus of the CAN frame is "CAN1." The source bus of a CAN frame containing a CAN-ID of "0x100" is "None," and the destination bus of the CAN frame is "CAN2."

[0065] 2, when relay unit 11 receives ID information E1 from discrimination unit 21, relay unit 11 identifies a destination bus corresponding to the CAN-ID indicated by the ID information E1 by referring to routing table Tb11 in storage unit 13. Then, relay unit 11 acquires a CAN frame including the CAN-ID from storage unit 13, and outputs the acquired CAN frame to the identified destination bus.

[0066] On the other hand, if the discrimination flag of the CAN-ID indicated by the ID information E1 received 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.

[0067] (Calculation Process) For example, the monitor 24 performs a calculation process to calculate 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.

[0068] More specifically, for example, the monitoring unit 24 calculates the estimated value of the bus load every time a calculation period T for the estimated value of the bus load elapses after the in-vehicle relay device 101 is started. 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 another value depending on the number of in-vehicle ECUs 202 that constitute the in-vehicle network 401, etc.

[0069] Specifically, for example, each time monitoring unit 24 receives ID information E1 from relay unit 11 during calculation period T, monitoring unit 24 refers to routing table Tb11 in storage unit 13 to identify a destination bus corresponding to the CAN-ID indicated by ID information E1. Then, for each identified destination bus, monitoring unit 24 counts the number of times that ID information E1 has been received from relay unit 11 during calculation period T, and calculates the count value as an estimate of the bus load on that destination bus.

[0070] In addition, the monitoring unit 24 is not limited to a configuration in which the above count value is calculated as an estimated value of the bus load, but may also be configured to calculate the total amount of data in the DAT field in each of the CAN frames stored in the memory unit 13 by the relay unit 11 during the calculation period T as an estimated value of the bus load.

[0071] After calculating the estimated value of the bus load, the monitoring unit 24 outputs the calculation result and load information indicating the corresponding destination bus to the compression processing unit 22.

[0072] For example, the compression processing unit 22 determines whether or not to perform compression processing based on the bus load estimation result by the monitoring unit 24 .

[0073] More specifically, for example, when the compression processing unit 22 receives one or more ID information E1 from the discrimination 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 greater than or equal to a predetermined threshold value Th.

[0074] (When the estimated value of bus load is less than the threshold value) For example, the compression processing unit 22 decides not to perform compression processing when the estimated value of bus load indicated by the load information received from the monitoring unit 24 is less than the threshold value Th. Then, the compression processing unit 22 checks the CAN-ID (hereinafter also referred to as "corresponding ID") corresponding to the destination bus indicated by the load information by referring to the routing table Tb11 in the storage unit 13.

[0075] When the compression processing unit 22 confirms the corresponding ID, it outputs one or more pieces of ID information E1 (hereinafter also referred to as "ID information E11") that indicate the same CAN-ID as the corresponding ID, from among the one or more pieces of ID information E1 received from the discrimination unit 21, to the relay unit 11. Here, an example in which the compression processing unit 22 outputs multiple pieces of ID information E11 to the relay unit 11 will be described.

[0076] When the relay unit 11 receives a plurality of pieces of ID information E11 from the compression processing unit 22, it acquires a plurality of CAN frames corresponding to the plurality of pieces of ID information E11 from the storage unit 13. Then, by referring to the routing table Tb11 in the storage unit 13, the relay unit 11 identifies, for each acquired CAN frame, a destination bus corresponding to the CAN-ID included in the CAN frame, and outputs the CAN frame to the identified destination bus.

[0077] (When the estimated value of bus load is equal to or greater than a threshold value) For example, the compression processing unit 22 determines to perform compression processing when the estimated value of bus load indicated by the load information received from the monitoring unit 24 is equal to or greater than a threshold value Th. Then, the compression processing unit 22 performs compression processing on the frames to be compressed determined by the determination unit 21.

[0078] More specifically, for example, when the compression processing unit 22 decides 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 identified corresponding ID, i.e., one or more frames to be compressed, from the storage unit 13. Below, an example will be described in which the compression processing unit 22 acquires a CAN frame FA including a CAN-ID of "0x000" and a CAN frame FB including a CAN-ID of "0x001" from the storage unit 13 as frames to be compressed.

[0079] When the compression processing unit 22 acquires the CAN frames FA and FB from the storage unit 13, the compression processing unit 22 compresses each of the CAN frames in accordance with a predetermined compression method C.

[0080] FIG. 6 is a diagram illustrating an example of a CAN frame created by the vehicle-mounted relay device according to the first embodiment of the present disclosure.

[0081] 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.

[0082] Then, the compression processing unit 22 outputs the frame F1 to which a specific CAN-ID for compression processing (hereinafter also referred to as "compression processing ID") is attached to the relay unit 11. In this example, the compression processing ID attached to the frame F1 created by the in-vehicle relay device 101A is "0x100".

[0083] FIG. 7 is a diagram illustrating an example of a CAN table stored by the vehicle-mounted relay device according to the first embodiment of the present disclosure.

[0084] 7, storage unit 13 stores CAN table Tb12 indicating the correspondence between CAN-IDs, the types of information included in CAN frames, the senders of CAN frames, and the destinations of CAN frames. CAN table Tb12 is registered in storage unit 13 by the manufacturer of vehicle 1, for example, when vehicle 1 is shipped.

[0085] In the CAN table Tb12 shown in FIG. 7 , the sender of a CAN frame containing a CAN-ID of "0x000" and an information type of "AAA" is the in-vehicle ECU 202A and the destination is the in-vehicle ECU 202E. The sender of a CAN frame containing a CAN-ID of "0x001" and an information type of "BBB" is the in-vehicle ECU 202B and the destination is the in-vehicle ECU 202D. The sender of a CAN frame containing a CAN-ID of "0x002" and an information type of "CCC" is the in-vehicle ECU 202C and the destination is the in-vehicle ECU 202F. The sender of a CAN frame containing a CAN-ID of "0x003" and an information type of "DDD" is the in-vehicle ECU 202A and the destination is the in-vehicle ECU 202G. The sender of a CAN frame containing a CAN-ID of "0x004" and an information type of "EEE" is in-vehicle ECU 202D and the destination is in-vehicle ECU 202B. The sender of a CAN frame containing a CAN-ID of "0x100" and an information type of "for compression processing" is in-vehicle relay device 101A and the destination is in-vehicle relay device 101B.

[0086] 3, after creating frame F1, compression processing unit 22 checks the compression processing ID by referring to CAN table Tb12 in storage unit 13. Specifically, for example, compression processing unit 22 checks that the CAN-ID corresponding to its own in-vehicle relay device 101, which is the sender, and the CAN frame whose information type is "for compression processing" is "0x100" in CAN table Tb12.

[0087] 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.

[0088] The relay unit 11 transmits the frame F1 created by the compression processing unit 22 to another vehicle-mounted relay device 101, that is, the vehicle-mounted relay device 101B, via the CAN bus 51B.

[0089] More specifically, for example, when relay unit 11 receives frame F1 from compression processing unit 22, relay unit 11 identifies a destination bus corresponding to the compression processing ID included in frame F1 by referring to routing table Tb11 in storage unit 13. Then, relay unit 11 outputs frame F1 to the identified destination bus, i.e., CAN bus 51B.

[0090] [Decompression Processing] In the vehicle-mounted relay device 101B, the decompression processing unit 23 performs decompression processing to decompress the frame F1 received from the vehicle-mounted relay device 101A.

[0091] More specifically, for example, the discrimination unit 21 performs discrimination processing D2 to discriminate CAN frames to be decompressed (hereinafter also referred to as “frames to be decompressed”) from among the CAN frames received by the relay unit 11. Discrimination processing D2 is an example of a second discrimination processing.

[0092] Specifically, for example, the storage unit 13 holds a CAN-ID corresponding to a frame to be decompressed (hereinafter also referred to as a "decompression target ID"). For example, the decompression target ID is a CAN-ID "0x100" corresponding to the type of information included in the CAN frame, "for compression processing," which is registered in the CAN table Tb12 shown in FIG.

[0093] For example, the discriminator 21 performs the discrimination process D2 using the decompression target ID. Specifically, for example, by referring to the reception list L in the memory unit 13, the discriminator 21 confirms that the discrimination flag of the CAN-ID included in the CAN frame received from the relay unit 11 is "0", and then reads out the CAN table Tb12 in the memory unit 13. Then, by referring to the CAN table Tb12, the discriminator 21 confirms whether the CAN-ID is the same as the CAN-ID corresponding to the information type "for compression processing".

[0094] If the CAN-ID indicated by the ID information E1 received from the relay unit 11 is the same as the decompression target ID registered in the CAN table Tb12, i.e., the CAN-ID corresponding to the information type "for compression processing," the discriminator 21 recognizes that the CAN frame including the CAN-ID indicated by the ID information E1 is the frame to be decompressed. Then, the discriminator 21 outputs the ID information E1 received from the relay unit 11 to the decompression processor 23.

[0095] As described above, in this embodiment, the compression processing ID "0x100" is stored in the ID field of the frame F1 transmitted from the in-vehicle relay device 101A. The compression processing ID "0x100" is the same as the decompression 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 a frame to be decompressed.

[0096] For example, the decompression processing unit 23 performs decompression processing on the decompression target frame determined by the determination unit 21 .

[0097] More specifically, for example, when the decompression processing unit 23 receives ID information E1 from the discrimination unit 21, it acquires a CAN frame including the CAN-ID indicated by the ID information E1, i.e., a frame to be decompressed, from the storage unit 13. Then, the decompression processing unit 23 decompresses one or more compressed CAN frames stored in the DAT field of the acquired CAN frame according to compression method C. In other words, the decompression processing unit 23 restores one or more CAN frames before compression by the compression processing unit 22 in the vehicle-mounted relay device 101A. Here, it is assumed that the decompression processing unit 23 restores multiple CAN frames.

[0098] Upon completing the decompression process, the decompression processing unit 23 detects the SOF field and the EOF field in the decompressed data and identifies one or more CAN frames. The decompression processing unit 23 then outputs the identified CAN frames to the relay unit 11. The decompression processing unit 23 also discards the frames to be decompressed that are stored in the storage unit 13.

[0099] The relay unit 11 relays the CAN frame after decompression processing by the decompression processing unit 23. More specifically, for example, when the relay unit 11 receives a CAN frame from the decompression processing unit 23, it identifies a destination bus corresponding to the CAN-ID included in the CAN frame by referring to the routing table Tb11 in the storage unit 13. Then, the relay unit 11 outputs the CAN frame to the identified destination bus.

[0100] 8 is a time chart showing an example of compression processing and decompression processing by the in-vehicle relay device according to the first embodiment of the present disclosure. As in FIG. 6, the symbol "FA" indicates a CAN frame including a CAN-ID of "0x000," and the symbol "FB" indicates a CAN frame including a CAN-ID of "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.

[0101] Referring to FIG. 8, it is assumed that CAN frames FA and FB are output to CAN bus 51A and in-vehicle relay device 101A receives CAN frames FA and FB.

[0102] Upon receiving the CAN frames FA and FB, the vehicle-mounted relay device 101A stores the CAN frames FA and FB in the storage unit 13 .

[0103] 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 checks whether the determination flag of the CAN-ID included in each CAN frame is “1” by referring to the reception list L shown in FIG.

[0104] When the vehicle-mounted relay device 101A confirms that the discrimination flag of the CAN-ID included in each of the CAN frames FA and FB is "1", it determines that the CAN frames FA and FB are frames to be compressed.

[0105] Then, based on the CAN frames FA and FB, the vehicle relay device 101A determines whether or not to perform compression processing in accordance with an estimated value of the bus load on the CAN bus 51B, which is the destination bus of the CAN frames FA and FB.

[0106] For example, as described above, when the calculated estimated value of the bus load on the CAN bus 51B is equal to or greater than the threshold value Th, the in-vehicle relay device 101A performs a compression process to compress the CAN frames FA and FB. Then, the in-vehicle relay device 101A stores the compressed CAN frames FA and FB in the DAT field and transmits the frame F1, in which the compression process ID "0x100" is stored in the ID field, to the in-vehicle relay device 101B via the CAN bus 51B.

[0107] When the in-vehicle relay device 101B receives the frame F1, it performs a determination process D2 using the CAN table Tb12 shown in FIG. 7 to determine whether the received frame F1 is a frame to be decompressed.

[0108] In the example shown in Figure 8, the vehicle relay device 101B determines that frame F1 is a frame to be decompressed because the CAN-ID "0x100" stored in the ID field of frame F1 is the same as the CAN-ID corresponding to the information type "for compression processing" registered in CAN table Tb12.

[0109] Then, the vehicle relay device 101B performs an expansion process to expand the compressed CAN frames FA and FB stored in the DAT field of frame F1, thereby restoring the CAN frames FA and FB to their pre-compression state, and performs a relay process on the restored CAN frames FA and FB.

[0110] [Operation Flow] FIGS. 9 and 10 are flowcharts defining an operation procedure when the vehicle-mounted relay device according to the first embodiment of the present disclosure performs compression processing and decompression processing.

[0111] 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).

[0112] Next, the vehicle-mounted relay device 101 stores the received CAN frame in the storage unit 13 (step S102).

[0113] 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 checks whether the determination flag of the CAN-ID included in the CAN frame stored in the storage unit 13 is “1” by referring to the reception list L in the storage unit 13 (step S103).

[0114] Then, if the discrimination flag of the CAN-ID contained in the CAN frame stored in the memory unit 13 is "1", i.e., if the CAN frame is a frame to be compressed (YES in step S104), the vehicle relay device 101 receives the CAN frame, stores the CAN frame, and performs discrimination process D1 (steps S101 to S103) until a predetermined time has elapsed, i.e., until the calculation period T has elapsed (NO in step S105).

[0115] Next, when the calculation period T has elapsed (YES in step S105), the in-vehicle relay device 101 refers to the routing table Tb11 in the storage unit 13 to identify, for each CAN frame stored in the storage unit 13, a destination bus corresponding to the CAN-ID included in the CAN frame. Here, it is assumed that one destination bus is identified (step S106).

[0116] Next, the vehicle-mounted relay device 101 calculates an estimated value of the bus load on the identified destination bus (step S107).

[0117] Next, if the calculated estimated bus load is equal to or greater than the threshold value Th (YES in step S108), the in-vehicle relay device 101 performs compression processing. For example, as described above, the in-vehicle relay device 101 compresses the CAN frame, which is the frame to be compressed, according to compression method C (step S109).

[0118] Next, the in-vehicle relay device 101 creates a frame F1 in which the compressed CAN frame is stored in the DAT field, and stores the compression processing ID in the ID field of the created frame F1 (step S110).

[0119] Next, the vehicle-mounted relay device 101 outputs the frame F1 to the identified destination bus (step S111).

[0120] On the other hand, if the calculated estimated value of the bus load is less than the threshold value Th (NO in step S108), the vehicle relay device 101 does not perform compression processing and outputs the CAN frame stored in the memory unit 13 to the identified destination bus (step S112).

[0121] Furthermore, if 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 an ID to be decompressed (step S113).

[0122] Next, if 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, and then discards the frame to be decompressed (step S115).

[0123] Next, the in-vehicle relay device 101 outputs the decompressed CAN frame to the destination bus. For example, as described above, the in-vehicle relay device 101 identifies a destination bus corresponding to the CAN-ID included in the decompressed CAN frame by referring to the routing table Tb11 in the storage unit 13, and outputs the decompressed CAN frame to the identified destination bus (step S116).

[0124] On the other hand, if the received CAN frame is neither a frame to be compressed nor a frame to be decompressed (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 identifies a destination bus corresponding to the CAN-ID included in the received CAN frame by referring to the routing table Tb11 in the storage unit 13, and outputs the CAN frame to the identified destination bus (step S117).

[0125] In the flowcharts shown in FIGS. 9 and 10, the vehicle-mounted relay device 101 is not limited to a configuration that performs both compression processing and decompression processing, but may be a configuration that performs either compression processing or decompression processing.

[0126] In addition, in the in-vehicle communication system 301 according to the first embodiment of the present disclosure, the in-vehicle relay device 101A performs compression processing, and the in-vehicle relay device 101B performs decompression processing of the compressed CAN frame received from the in-vehicle relay device 101A. However, this is not limited to this. The in-vehicle relay device 101B may perform compression processing, and the in-vehicle relay device 101A may perform decompression processing of the compressed CAN frame received from the in-vehicle relay device 101B.

[0127] Furthermore, in the in-vehicle communication system 301 according to the first embodiment of the present disclosure, the in-vehicle relay device 101A performs a discrimination process D1 to discriminate frames to be compressed from among the received frames, and the in-vehicle relay device 101B performs a discrimination process D2 to discriminate frames to be decompressed from among the received frames, but this is not limited to this. The in-vehicle relay device 101A may be configured to compress all CAN frames whose destination bus is the CAN bus 51B without performing the discrimination process D1. 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.

[0128] Furthermore, in the in-vehicle communication system 301 according to the first embodiment of the present disclosure, the in-vehicle relay device 101 is configured to perform the determination process D1 by checking whether the CAN-ID included in the received CAN frame is an ID to be compressed, but this is not limited to this. The in-vehicle relay device 101 may be configured to perform the determination process D1 using information other than the CAN-ID stored in the CAN frame.

[0129] Furthermore, in the in-vehicle communication system 301 according to the first embodiment of the present disclosure, the in-vehicle relay device 101 is configured to perform the determination process D2 by checking whether the CAN-ID included in the received CAN frame is an ID to be decompressed, but this is not limited to this. The in-vehicle relay device 101 may be configured to perform the determination process D2 using information other than the CAN-ID stored in the CAN frame.

[0130] In addition, in the in-vehicle communication system 301 according to the first embodiment of the present disclosure, the in-vehicle relay device 101 is configured not to perform compression processing of the operation frame, but this is not limited thereto. The in-vehicle relay device 101 may be configured to perform compression processing of the operation frame.

[0131] In addition, in the in-vehicle communication system 301 according to the first embodiment of the present disclosure, the in-vehicle relay device 101A is configured to transmit to the in-vehicle relay device 101B a CAN frame with a specific CAN-ID for compression processing, i.e., a frame F1 in which the compression processing ID is stored in the ID field, but this is not limited to this. The in-vehicle relay device 101A may also be configured to transmit to the in-vehicle relay device 101B a frame F1 in which specific information for compression processing is stored in a field other than the ID field.

[0132] Furthermore, in the in-vehicle communication system 301 according to the first embodiment of the present disclosure, the in-vehicle relay device 101 is configured to determine whether to perform compression processing based on the estimated bus load on the CAN bus 51 to which the CAN frame is relayed. However, this is not limited to this. The in-vehicle relay device 101 may be configured to perform compression processing regardless of the estimated bus load. Furthermore, the in-vehicle relay device 101 may be configured to determine whether to perform compression processing based on the number of in-vehicle ECUs 202 connected to the in-vehicle relay device 101. 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 the in-vehicle relay device 101 is equal to or greater than a predetermined threshold.

[0133] Next, other embodiments of the present disclosure will be described with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference numerals and their description will not be repeated.

[0134] 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. The in-vehicle communication system 302 is the same as the in-vehicle communication system 301 according to the first embodiment except for the contents described below.

[0135] 11 is a diagram illustrating a configuration of an in-vehicle communication system according to a second embodiment of the present disclosure. Referring to FIG. 11 , for example, an in-vehicle communication system 302 includes three or more in-vehicle relay devices 101. Specifically, for example, compared to the in-vehicle communication system 301 illustrated in FIG. 1 , the in-vehicle communication system 302 further includes in-vehicle relay devices 101C and 101D, which are in-vehicle relay devices 101. The in-vehicle relay device 101D is an example of a third in-vehicle relay device.

[0136] 11, the in-vehicle relay device 101C is connected to the in-vehicle relay device 101A via a CAN bus 51B, and the in-vehicle relay device 101D is connected to the in-vehicle relay device 101A via a CAN bus 51C.

[0137] 1, the in-vehicle communication system 302 further includes in-vehicle ECUs 202J, 202K, 202L, and 202M that are in-vehicle ECUs 202.

[0138] 11 , in-vehicle ECUs 202J and 202K are connected to in-vehicle relay device 101C via CAN bus 51E, which is also a CAN bus 51. In-vehicle ECUs 202L and 202M are connected to in-vehicle relay device 101D via CAN bus 51F, which is also a CAN bus 51.

[0139] In this 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.

[0140] The individual ECUs are connected to detecting devices and actuators (not shown). The detecting devices are, for example, various sensors. The individual ECUs transmit detected data received from the detecting devices to the integrated ECU.

[0141] The integrated ECU generates control information for driving the actuators based on the detection data received from the individual ECUs, and the individual ECUs transmit the generated control information to the individual ECUs that have transmitted the detection data or to individual ECUs other than the individual ECUs that have transmitted the detection data.

[0142] The individual ECUs drive the actuators connected to them based on the control information received from the integrated ECU.

[0143] 12 is a diagram illustrating an example of a CAN table Tb22 stored in the vehicle-mounted relay device 101A, 101B, and 101C according to the second embodiment of the present disclosure.

[0144] In CAN table Tb22 shown in Figure 12, compared to CAN table Tb12 shown in Figure 7, the source "vehicle relay device 101A" and destination "vehicle relay device 101C" of the CAN frame containing the CAN-ID "0x101" and the information type "for compression processing" have been added.

[0145] Referring again to Figure 3, in the vehicle-mounted relay device 101A, when the compression processing unit 22 transmits frame F1 shown in Figure 6 to the vehicle-mounted relay device 101C via the CAN bus 51B, it refers to the CAN table Tb22 in the memory unit 13 to confirm that the source and destination are the vehicle-mounted relay device 101A and the vehicle-mounted relay device 101C, respectively, and that the CAN-ID corresponding to the CAN frame whose information type is "for compression processing" is "0x101".

[0146] Then, the compression processing unit 22 transmits the frame F1 in which the CAN-ID "0x101" is stored in the ID field to the vehicle-mounted relay device 101C via the relay unit 11.

[0147] [On-Vehicle Relay Device 101C] The on-vehicle relay device 101C performs a determination process D2 to determine, from the received CAN frames, frames to be decompressed by the on-vehicle relay device 101C.

[0148] More specifically, for example, in the in-vehicle relay device 101C, the discrimination unit 21 performs discrimination process D2 using the decompression target ID. In this embodiment, for example, the decompression target ID of the in-vehicle relay device 101C is the CAN-ID "0x101" corresponding to the CAN frame destination "in-vehicle relay device 101C" and the information type "for compression processing" registered in the CAN table Tb22 shown in FIG.

[0149] For example, when the discrimination unit 21 receives ID information E1 from the relay unit 11, it refers to the CAN table Tb22 in the memory unit 13 to check whether the CAN-ID indicated by the ID information E1 is the same as the decompression target ID "0x101".

[0150] If the CAN-ID indicated by the ID information E1 received from the relay unit 11 is the same as the decompression target ID "0x101", the discriminator 21 recognizes that the CAN frame including the CAN-ID is a frame to be decompressed by the in-vehicle relay device 101C. Then, the discriminator 21 outputs the ID information E1 received from the relay unit 11 to the decompression processor 23.

[0151] As described above, in this embodiment, the compression processing ID "0x101" is stored in the ID field of frame F1 transmitted from in-vehicle relay device 101A. This compression processing ID "0x101" is the same as the decompression target ID of in-vehicle relay device 101C registered in CAN table Tb22, i.e., the CAN-ID corresponding to the CAN frame destination "in-vehicle relay device 101C" and the information type "for compression processing." Therefore, the discrimination unit 21 in in-vehicle relay device 101C recognizes that frame F1 is a decompression target frame for in-vehicle relay device 101C.

[0152] On the other hand, if the CAN-ID indicated by the ID information E1 received from the relay unit 11 is different from the decompression target ID "0x101", the discriminator 21 recognizes that the CAN frame including the CAN-ID is not a frame to be decompressed by the in-vehicle relay device 101C. Then, the discriminator 21 outputs the ID information E1 to the relay unit 11.

[0153] 3 and 5, when relay unit 11 receives ID information E1 from discrimination unit 21, relay unit 11 identifies a destination bus corresponding to the CAN-ID indicated by the ID information E1 by referring to routing table Tb11 in storage unit 13. Then, relay unit 11 acquires a CAN frame including the CAN-ID from storage unit 13, and outputs the acquired CAN frame to the identified destination bus.

[0154] [In-vehicle relay device 101D] In in-vehicle communication system 302, the bus load of CAN bus 51C is smaller than the bus load of other CAN buses 51. In this case, for example, in-vehicle relay device 101D connected to CAN bus 51C does not perform compression processing or decompression processing.

[0155] More specifically, for example, when the in-vehicle relay device 101D receives a CAN frame with the CAN bus 51C as the destination bus from the in-vehicle ECU 202L or the in-vehicle ECU 202M connected to it, the in-vehicle relay device 101D performs relay processing on the received CAN frame without compressing it.

[0156] Also, for example, in the in-vehicle relay device 101A, the CAN table Tb22 in the storage unit 13 does not register a CAN-ID corresponding to a CAN frame whose source and destination are the in-vehicle relay device 101A and the in-vehicle relay device 101D, respectively, and whose information type is "for compression processing." In other words, the in-vehicle relay device 101A does not transmit the frame F1 to the in-vehicle relay device 101D via the CAN bus 51C. Furthermore, the in-vehicle relay device 101D does not perform decompression processing.

[0157] The other configurations and operations are similar to those of the in-vehicle communication system 301 according to the first embodiment, and therefore detailed description thereof will not be repeated here.

[0158] The above-described embodiments should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims.

[0159] Each process (each function) in the above-described embodiments is realized by a processing circuit including one or more processors. The processing circuit may be configured as an integrated circuit or the like that combines one or more memories, various analog circuits, and various digital circuits in addition to the one or more processors. The one or more memories store programs (instructions) that cause the one or more processors to execute each of the processes. The one or more processors may execute each of the processes according to the program read from the one or more memories, or may execute each of the processes according to a logic circuit designed in advance to execute each of the processes. The processor may be any of 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 physically separated processors may cooperate with each other to execute the processes. For example, the processors installed in the physically separated computers may cooperate with each other via a network such as a LAN (Local Area Network), a WAN (Wide Area Network), or the Internet to execute the processes. The program may be installed into the memory from an external server device or the like via the network, or may be distributed in a state stored on a recording medium such as a CD-ROM (Compact Disc Read Only Memory), a DVD-ROM (Digital Versatile Disc Read Only Memory), or a semiconductor memory, and then installed into the memory from the recording medium.

[0160] The above description includes the following additional features: [Supplementary Note 1] A relay method in an in-vehicle communication system including a plurality of in-vehicle devices and a plurality of in-vehicle relay devices, wherein the plurality of in-vehicle relay devices include 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 performing a relay process to relay frames transmitted and received between the in-vehicle devices, the relay method including a step in which the first in-vehicle relay device performs a compression process to compress the frames and transmits the compressed frames to the second in-vehicle relay device via the communication bus, and a step in which the second in-vehicle relay device performs a decompression process to decompress the compressed frames received from the first in-vehicle relay device and perform the relay process of the decompressed frames.

[0161] [Appendix 2] A relay program used in an in-vehicle communication system having a plurality of in-vehicle devices, which is used in an in-vehicle relay device that performs relay processing to relay frames transmitted and received between the in-vehicle devices, wherein the in-vehicle relay device is connected to other in-vehicle relay devices via a CAN bus, and the relay program causes a computer to function as: a relay unit that receives the frames; and a compression processing unit that performs compression processing to compress the frames received by the relay unit, and the relay unit transmits the frames after the compression processing by the compression processing unit to the other in-vehicle relay devices via the communication bus.

[0162] [Supplementary Note 3] An in-vehicle relay device used in an in-vehicle communication system having a plurality of in-vehicle devices, which performs relay processing to relay frames transmitted and received between the in-vehicle devices, wherein the in-vehicle relay device is connected to other in-vehicle relay devices via a CAN bus, and comprises a processing circuit, which receives the frames, performs compression processing to compress the received frames, and transmits the frames after the compression processing to the other in-vehicle relay devices via the communication bus.

[0163] REFERENCE SIGNS LIST 1 vehicle 11 relay unit 12 processing unit 13 storage unit 21 determination unit 22 compression processing unit 23 decompression processing unit 24 monitoring unit 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. An in-vehicle communication system comprising: a plurality of in-vehicle devices; and a plurality of in-vehicle relay devices including 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, wherein the in-vehicle relay devices perform a relay process to relay frames transmitted and received between the in-vehicle devices, the first in-vehicle relay device performs a compression process to compress the frames, and transmits the frames after the compression process to the second in-vehicle relay device via the communication bus, and the second in-vehicle relay device performs an decompression process to decompress the frames after the compression process received from the first in-vehicle relay device, and performs the relay process of the frames after the decompression process.

2. The in-vehicle communication system described in claim 1, wherein the first in-vehicle repeater performs a first discrimination process to discriminate from the received frames which are frames to be compressed, which are frames to be subjected to the compression process, and performs the compression process on the discriminated frames to be compressed; and the second in-vehicle repeater performs a second discrimination process to discriminate from the received frames which are frames to be decompressed, which are frames to be subjected to the decompression process, and performs the decompression process on the discriminated frames to be decompressed.

3. The in-vehicle communication system described in claim 2, wherein the first in-vehicle relay device holds first identification information corresponding to the frame to be compressed and performs the first discrimination process using the first identification information it holds, and the second in-vehicle relay device holds second identification information corresponding to the frame to be decompressed and performs the second discrimination process using the second identification information it holds.

4. An in-vehicle communication system as described in any one of claims 1 to 3, wherein the first in-vehicle relay device does not perform the compression processing of driving frames, which are frames related to the operation of a vehicle in which the in-vehicle communication system is installed.

5. An in-vehicle communication system as described in any one of claims 1 to 4, wherein the first in-vehicle relay device receives the frame conforming to the CAN standard, and the first in-vehicle relay device transmits the frame after the compression process, with a specific CAN-ID for compression processing attached, to the second in-vehicle relay device via the communication bus.

6. An in-vehicle communication system according to any one of claims 1 to 5, wherein the first in-vehicle relay device determines whether or not to perform the compression processing based on an estimated communication load on the communication bus.

7. The in-vehicle communication system according to any one of claims 1 to 6, comprising three or more in-vehicle relay devices, and a third in-vehicle relay device does not perform the compression processing and the decompression processing.

8. An in-vehicle relay device used in an in-vehicle communication system having a plurality of in-vehicle devices, which performs relay processing to relay frames transmitted and received between the in-vehicle devices, wherein the in-vehicle relay device is connected to the other in-vehicle relay devices via a communication bus, and comprises a relay unit that receives the frames, and a compression processing unit that performs compression processing to compress the frames received by the relay unit, and the relay unit transmits the frames after the compression processing by the compression processing unit to the other in-vehicle relay devices via the communication bus.

9. The vehicle-mounted relay device described in claim 8, wherein the relay unit further receives the frame after the compression processing transmitted from the other vehicle-mounted relay device, the vehicle-mounted relay device further includes an expansion processing unit that performs an expansion processing to expand the frame after the compression processing received by the relay unit, and the relay unit performs the relay processing of the frame after the expansion processing by the expansion processing unit.

10. A relay method in an in-vehicle relay device used in an in-vehicle communication system having a plurality of in-vehicle devices, which performs relay processing to relay frames transmitted and received between the in-vehicle devices, wherein the in-vehicle relay device is connected to other in-vehicle relay devices via a communication bus, and the relay method includes the steps of receiving the frames, performing a compression processing to compress the received frames, and transmitting the frames after the compression processing to the other in-vehicle relay devices via the communication bus.

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