Vehicular communication device

A vehicular communication device is provided. The vehicular communication device includes a reception section that, from a periphery vehicle equipped with a wide area communicator, receives a communication performance index representing performance of the wide area communicator, and a controller. The controller includes a reference value setup section that successively settles a reference value as a criterion based on the communication performance indexes received from multiple periphery vehicles, an acquisition section that acquires the communication performance index for a targeted wide area communicator which is the wide area communicator targeted at anomaly determination, and an anomaly determination section that determines an anomaly of the targeted wide area communicator based on comparison between the reference value settled by the reference value setup section and the communication performance index acquired by the acquisition section for the targeted wide area communicator.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a U.S. National Phase Application under 35 U.S.C. 371 of International Application No. PCT/JP2016/000436 filed on Jan. 28, 2016 and published in Japanese as WO 2016/125468 A1 on Aug. 11, 2016. This application is based on and claims the benefit of priority from Japanese Patent Application No. 2015-019512 filed on Feb. 3, 2015. The entire disclosures of all of the above applications are incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to a vehicular communication device that determines an anomaly of a wide area communicator.

BACKGROUND ART

Conventionally, there is known a technology that detects anomaly occurring on a device used for vehicles. Patent Literature 1 discloses the technology that uses a shock sensor included in an in-vehicle device to detect anomaly occurring on the in-vehicle device.

Further, there is known a system in which a vehicular communication device wirelessly communicates with devices outside a vehicle to enable a driver of a subject vehicle to use various services (hereinafter referred to as in-vehicle communication services). There is known an in-vehicle communication service, as an example, in which the vehicular communication device includes a wide area communicator that communicates with a server apparatus via a wide area communication network to transmit and receive various types of information.

The information transmitted from the wide area communicator to the server apparatus includes an emergency notification, for example. The information transmitted from the server apparatus to the wide area communicator includes map data, for example.

PRIOR ART LITERATURES

Patent Literature

SUMMARY OF INVENTION

The driver cannot appropriately receive an inter-vehicle communication if a wide area communicator is abnormal when the wide area communicator is used to receive in-vehicle communication services. It is therefore necessary to determine anomaly on the wide area communicator.

The wide area communicator may be determined to be abnormal when the communication performance of the wide area communicator degrades. However, the communication environment of the wide area communicator dynamically changes because the vehicular communication device is used for a vehicle acing as a mobile object. The communication performance of the wide area communicator degrades in a tunnel even though the wide area communicator is not abnormal, for example. The communication performance of the wide area communicator is likely to degrade when the wide area communicator is close to a periphery vehicle mounted with a vehicular communication device or is close to many devices including wide area communicators other than the vehicular communication device in the vicinity. It has been therefore difficult to accurately determine an anomaly on the wide area communicator based only on the communication performance of the wide area communicator.

In consideration of the foregoing, it is an object of the present disclosure to provide a vehicular communication device capable of accurately determining an anomaly of a wide area communicator.

A vehicular communication device used for a vehicle in an aspect of the present disclosure comprises: a reception section that, from a periphery vehicle equipped with a wide area communicator to connect a wide area communication network for performing communication, receives a communication performance index representing performance of the wide area communicator; a reference value setup section that successively settles a reference value as a criterion for the communication performance index based on the communication performance indexes received by the reception section from a plurality of the periphery vehicles; an acquisition section that acquires the communication performance index for a targeted wide area communicator, wherein a targeted wide area communicator is the wide area communicator targeted at anomaly determination; and an anomaly determination section that determines an anomaly of the targeted wide area communicator based on comparison between the reference value settled by the reference value setup section and the communication performance index acquired by the acquisition section for the targeted wide area communicator.

In the vehicular communication device, the reference value setup section sets a reference value based on communication performance indexes acquired from a plurality of periphery vehicles. The reference value therefore varies with an influence of the communication environment when the communication performance of a wide area communicator varies with the influence of the communication environment.

The anomaly determination on a targeted wide area communicator is performed based on comparison between the reference value and the communication performance index for the targeted wide area communicator. It is therefore possible to accurately distinguish between the case where the communication performance index for the targeted wide area communicator is abnormal due to an anomaly of the targeted wide area communicator and the case where the targeted wide area communicator is not abnormal but the communication performance index for the targeted wide area communicator indicates an abnormal value. Anomaly of the targeted wide area communicator can therefore be determined accurately.

EMBODIMENTS FOR CARRYING OUT INVENTION

(Overall Configuration of a Communication System1)

An embodiment will be described with reference to the accompanying drawings. A communication system1as illustrated inFIG. 1includes: an in-vehicle device3aused for a subject vehicle2a; an in-vehicle device3bused for a periphery vehicle2blocated in the vicinity of the subject vehicle2a; a roadside device4installed at a roadside; and a center apparatus (hereinafter referred to as a center)5.

The in-vehicle device3aand the in-vehicle device3buse the same configuration according to the embodiment. The subject vehicle2aand the periphery vehicle2bare therefore distinguished for convenience sake. Any of the vehicles2can be the subject vehicle2a. The periphery vehicle2bis assumed to be the vehicle2that exists in the vicinity of the subject vehicle2aand uses the in-vehicle device3. In the description below, the nomenclature of vehicle2is simply used when the subject vehicle2aand the periphery vehicle2bare not distinguished. The nomenclature of in-vehicle device3is simply used when the in-vehicle device3aand the in-vehicle device3bare not distinguished. The in-vehicle device3corresponds to a vehicular communication device.

The in-vehicle device3aand the in-vehicle device3btransmit and receive information by using inter-vehicle communication, namely, wireless communication without using a communication network. The inter-vehicle communication covers a communication range of several hundreds of meters. The in-vehicle device3and the roadside device4transmit and receive information by using vehicle roadside communication, namely, wireless communication without using a communication network. The in-vehicle device3and the center5perform wide area communication via a wide area communication network6.

The roadside device4performs the vehicle roadside communication with the in-vehicle device3to exchange information about service provision when the in-vehicle device3is used for the vehicle2that is located in a wireless communication area for the roadside device4. The wireless communication area for the roadside device4can be variously changed depending on service types. The wireless communication area approximates to several tens to hundreds of meters from the roadside device4, for example.

A center5is provided as a server apparatus and receives a notification that is transmitted from an in-vehicle device3by using wide area communication. The notification includes an anomaly notification about a wide area communicator32(seeFIG. 2) included in the in-vehicle device3bof a periphery vehicle2b.

(Configuration of the In-Vehicle Device3)

The configuration of the in-vehicle device3will be described. The description below aboutFIGS. 2 through 6explains the configuration of the in-vehicle device3amounted on the subject vehicle2a. As above, however, the same configuration is used for the in-vehicle device3amounted on the subject vehicle2aand the in-vehicle device3bmounted on the periphery vehicle2b.

The in-vehicle device3amay be fixed to a member included in the subject vehicle2aby using a bolt or an adhesive so that the in-vehicle device3acan hardly be brought out of the subject vehicle2a. Alternatively, the in-vehicle device3amay be mounted on the subject vehicle2aby being fixed to a holder so that the in-vehicle device3acan be detached from the holder without using a tool. The in-vehicle device3ais assumed to be normally mounted on the subject vehicle2aat a dashboard facing a windshield.

As illustrated inFIG. 2, the in-vehicle device3includes a narrow area communicator31, a wide area communicator32, a position detector33, a storage unit36, a controller37, and a notifier38.

The narrow area communicator31can be also referred to as an inter-vehicle communicator or a vehicle roadside communicator and communicates with the outside of a subject vehicle2aby using inter-vehicle communication and vehicle roadside communication. The narrow area communicator31covers a communication range comparable to a radius of approximately several hundreds of meters. The narrow area communicator31communicates with the in-vehicle device3bmounted on the periphery vehicle2band with a roadside device4. The narrow area communicator31serves as a receiver to receive a communication performance index for the wide area communicator32included in the in-vehicle device3bfrom the in-vehicle device3bof the periphery vehicle2b.

The vicinity in the embodiment signifies the communication range of the narrow area communicator31. The narrow area communicator31modulates and demodulates a received signal and outputs demodulated data to the controller37. The narrow area communicator31modulates data input from the controller37, converts the data into an electromagnetic wave, and transmits it.

The wide area communicator32connects with the wide area communication network6to communicate with the center5outside the subject vehicle2a, for example. The wide area communicator32demodulates a signal received via the wide area communication network6and outputs the signal to the controller37. The wide area communicator32modulates a baseband signal input from the controller37and transmits the signal to the center5.

During communication with the outside, the wide area communicator32specifies any one of an RSSI (Received Signal Strength Indication), an average communication rate, a communication success rate, and the number of received error frames as a communication performance index. The communication performance index is predetermined to represent which of these. The communication performance index represents the same one for the different in-vehicle devices3.

The RSSI is specified based on the electric power of a received electromagnetic. The average communication rate is specified based on the quantity of data received during a specified time. The communication success rate is calculated from the number of frames received during a given time period and the number of successfully decoded frames. The number of received error frames provides the number of frames resulting in errors during a given time, namely, the number of unsuccessfully decoded frames.

The wide area communicator32successively outputs the specified communication performance index to the controller37. The wide area communicator32also output telecommunications carrier information along with the communication performance index to the controller37. The telecommunications carrier information represents a telecommunications carrier that manages a wide area communication network6connected to the wide area communicator32. The telecommunications carrier information is represented by a numeric value associated with the telecommunications carrier, for example.

The position detector33includes a GNSS receiver used for GNSS (Global Navigation Satellite System) and successively (e.g., at a given cycle) detects a current position of the subject vehicle2abased on a positioning signal received from a positioning satellite. The current position is represented in latitude, longitude, and altitude. The position detector33successively (e.g., every 100 milliseconds) outputs the detected current position to the controller37.

In addition, the position detector33successively specifies a satellite signal quality index based on a positioning signal received by the GNSS receiver from the positioning satellite. The satellite signal quality index represents C/N (dB) or the number of satellites from which positioning signals are received, for example. The satellite signal quality index corresponds to positioning result information.

The communication performance index is predetermined to specifically represent which of values. The satellite signal quality index represents the same one for the different in-vehicle devices3. The position detector33also successively outputs the specified satellite signal quality index to the controller37.

The storage unit36is writable and includes a subject vehicle storage area36aand a periphery vehicle storage area36b. The subject vehicle storage area36astores the communication performance index supplied from the wide area communicator32to the controller37and the satellite signal quality index and the telecommunications carrier information supplied from the position detector33to the controller37. The periphery vehicle storage area36bstores the communication performance index, the satellite signal quality index, and the telecommunications carrier information received from the periphery vehicle2b.

The controller37is provided as a typical computer including a CPU371, ROM372, and RAM373. The ROM372stores a control program. The CPU371executes the control program stored in the ROM372by using a temporary storage function of the RAM373. The controller37thereby performs processes illustrated inFIGS. 3 through 6.

The controller37stores the communication performance index supplied from the wide area communicator32and the satellite signal quality index supplied from the position detector33as well as time points of storing in the subject vehicle storage area36aof the storage unit36. The controller37deletes a communication performance index and a satellite signal quality index expiring a predetermined retention time from communication performance indexes and satellite signal quality indexes stored in the subject vehicle storage area36aof the storage unit36. The retention time is short enough to be highly likely to cause an acceptable change in the communication performance index and the satellite signal quality index due to a change in the communication environment while the subject vehicle2ais traveling. The retention time is predetermined based on experiments. All or part of the functions performed by the controller37may be configured as hardware by using one or more IC modules.

The notifier38is available as either or both of a display and a speaker and is used to notify an occupant of the subject vehicle2athat the wide area communicator32is abnormal.

(Processes of the Controller37)

The controller37, when powered on, performs processes illustrated inFIGS. 3 through 5each at a corresponding predetermined cycle. The description below first explains an information transmission process inFIG. 3.

At step S1, it is determined whether an information transmission cycle is reached. The information transmission cycle ranges from one to several hundreds of milliseconds. The process inFIG. 3terminates if the determination at step S1results in NO. The process proceeds to step S2if the determination results in YES.

At step S2, the most recent satellite signal quality index, the most recent communication performance index, and the telecommunications carrier information are acquired from the subject vehicle storage area36aof the storage unit36.

At step S3, the narrow area communicator31transmits, to the surrounding of the subject vehicle2a, the most recent satellite signal quality index, the most recent communication performance index, and the telecommunications carrier information acquired at step S2along with a vehicle ID of the subject vehicle2a. The vehicle ID of the subject vehicle2ais stored in a given storage unit such as the ROM372. An ID of the in-vehicle device3acan be used as the vehicle ID of the subject vehicle2a. The narrow area communicator31uses a broadcast system as a transmission system, for example. However, the transmission system may use a unicast or multicast system that specifies the periphery vehicle2bas an information transmission destination.

The description below explains an information reception process illustrated inFIG. 4. At step S11, it is determined whether information is transmitted from the in-vehicle device3bmounted on the periphery vehicle2b. Specifically, the periphery vehicle2bperforms step S3inFIG. 3as above and the narrow area communicator31of the in-vehicle device3areceives the information. The narrow area communicator31then supplies the decoded data as above. At step S11, it is determined whether the decoded data is supplied from the narrow area communicator31. The process directly proceeds to step S13if the determination results in NO. The process proceeds to step S12if the determination results in YES.

At step S12, the information acquired from the narrow area communicator31is stored in the periphery vehicle storage area36bof the storage unit36along with the storing time point. The most recent information acquired from the narrow area communicator31is stored and information whose retention time expires is deleted.

The periphery vehicle2btransmits the same type of information the subject vehicle2atransmits at step S3inFIG. 3. The information transmitted from the periphery vehicle2btherefore includes the satellite signal quality index, the communication performance index, the telecommunications carrier information, and the vehicle ID of the periphery vehicle2b.

Steps S13and S14correspond to a reference value setup section. At step S13, it is determined whether a reference value update cycle is reached. The reference value update cycle is predetermined and takes effect longer than or equal to an information transmission cycle. The process inFIG. 4terminates if the determination results in NO. The process proceeds to S14if the determination results in YES.

At step S14, the reference value is updated based on a reference value generation set, namely, the most recent communication performance index stored in the periphery vehicle storage area36bof the storage unit36in terms of each periphery vehicle2b. The reference value generation set may include the given number of communication performance indexes from the most recent one in addition to the most recent communication performance index. The reference value generation set may include communication performance indexes corresponding to a given time period from the most recent one.

No reference value is specified when the in-vehicle device3ais powered. Thus, when S14is performed for the first time after power on of the in-vehicle device3a, the reference value is specified, not updated.

A specific reference value generated from the reference value generation set uses any one of an average value, a median value, and a mode value for communication performance indexes included in the reference value generation set. No reference value may be generated if the number of reference value generation sets is smaller than the minimum number of reference value generation sets to ensure the reliability of reference values. The minimum number is 2 or larger. Specifically, any numeric values are available. The reference value generation set may include the communication performance index for the subject vehicle2a.

The description below explains an anomaly determination process illustrated inFIG. 5. At step S21, it is determined whether an anomaly determination cycle elapses from the previous anomaly determination or from the time to start a power-on sequence if the anomaly determination is not performed yet. The process inFIG. 5terminates if the determination results in NO. The process proceeds to step S22if the determination results in YES.

At step S22, it is determined whether the current area is capable of satisfactorily receiving a positioning signal. The determination uses the most recent satellite signal quality index that is stored in the periphery vehicle storage area36bof the storage unit36in terms of each periphery vehicle2b. The most recent satellite signal quality index is compared with a predetermined signal quality threshold value. The periphery vehicle2bhaving transmitted the satellite signal quality index is assumed not to satisfactorily receive the positioning signal if the satellite signal quality index is smaller than the signal quality threshold value as a result of the comparison. The current area is assumed not to be capable of satisfactorily receiving the positioning signal if the number of or a ratio of periphery vehicles2bincapable of satisfactorily receiving the positioning signal exceeds an unsuccessful reception determination threshold value. In this case, the determination at step S22results in NO. The process inFIG. 5terminates if the determination at step S22results in NO.

The determination at step S22results in YES and the process proceeds to S23if the current area is determined to be capable of satisfactorily receiving the positioning signal.

In step S23corresponding to a roaming determination section, it is determined whether the current position is located in a global roaming area. The determination is performed by comparing the telecommunications carrier information stored in the periphery vehicle storage area36bof the storage unit36with telecommunications carrier information predetermined for each country. The current position is determined to be located in a global roaming area if the telecommunications carrier information stored in the periphery vehicle storage area36bincludes the telecommunications carrier information for multiple countries. The global roaming area changes the telecommunications carrier that manages the wide area communication network6to which the wide area communicator32connects. The global roaming area corresponds to a changeover area.

The determination at step S23results in YES if the current position is located in the global roaming area. In this case, the process inFIG. 5terminates. The determination at step S23results in NO if the current position is determined not to be located in the global roaming area. In this case, the process proceeds to step S24inFIG. 6.

At step S24as an acquisition section, the most recent communication performance index corresponding to the wide area communicator32of the periphery vehicle2btargeted at the anomaly determination is acquired from the periphery vehicle storage area36bof the storage unit36.

A targeted wide area communicator represents the wide area communicator32of the periphery vehicle2bwhen the wide area communicator32is targeted at the anomaly determination. The wide area communicator32of the periphery vehicle2btargeted at the anomaly determination equals at least one of wide area communicators32for which the reference value generation set includes the communication performance index. In the description below, the wide area communicators32for which the reference value generation set includes the communication performance index are all assumed to be targeted wide area communicators32.

At step S25as an anomaly determination section, the communication performance index acquired at step S24is compared with the reference value to determine whether the wide area communicator32corresponding to the communication performance index acquired at step S24is abnormal.

The wide area communicator32of the periphery vehicle2btransmitting the communication performance index is determined to be abnormal when an anomaly determination condition is satisfied as a result of the comparison between the communication performance index and the reference value. The anomaly determination condition is satisfied when a difference between the reference value and the communication performance index is larger than an anomaly determination threshold value predetermined for the difference, for example. The anomaly determination condition may be satisfied when a ratio between the reference value and the communication performance index exceeds an anomaly determination range predetermined for the ratio.

At step S26, it is determined whether the anomaly determination on the targeted wide area communicator32of the periphery vehicle2bterminates. The process returns to step S24if the determination results in NO. At step S24, in this case, the most recent communication performance index is acquired from the periphery vehicle storage area36bof the storage unit36on condition that the communication performance index corresponds to the periphery vehicle2bon which the anomaly determination is not yet performed.

The process proceeds to step S27if the determination at step S26results in YES. At step S27, it is determined whether the repetition from steps S24through S26determines the wide area communicator32to be abnormal. The process proceeds to step S29if the determination results in NO. The process proceeds to step S28if the determination results in YES.

At step S28as a first anomaly notification processing section, the wide area communicator32of the subject vehicle2anotifies the center5of a message signifying that the wide area communicator32of the periphery vehicle2bdetermined to be abnormal is abnormal. Repeated notification is unneeded if the same contents are already notified to the center5. The notification also includes the vehicle ID of the periphery vehicle2bmounted with the wide area communicator32determined to be abnormal. The wide area communicator32of the subject vehicle2acorresponds to a specified communicator.

At step S29as the acquisition section, the targeted narrow area communicator is identified with the wide area communicator32of the subject vehicle2a. The most recent communication performance index for the wide area communicator32of the subject vehicle2ais acquired from the subject vehicle storage area36aof the storage unit36.

At step S30as the anomaly determination section, the communication performance index acquired at step S29is compared with the reference value and it is determined whether the wide area communicator32of the subject vehicle2ais abnormal. The anomaly determination uses the same method as step S25.

At step S31, it is determined whether the wide area communicator32of the subject vehicle2ais determined to be abnormal as a result of the anomaly determination at step S30. The process inFIG. 6terminates if the determination results in NO. The process proceeds to step S32if the determination results in YES.

At step S32as a second anomaly notification processing section, the notifier38notifies that the wide area communicator32of the subject vehicle2ais abnormal.

(Overview of the First Embodiment)

The configuration of the first embodiment uses the reference value generation set including a communication performance index acquired from the periphery vehicle2bexisting in the communication range for the narrow area communicator31of the subject vehicle2a. The reference value is therefore settled from communication performance indexes included in the reference value generation set (S14).

The communication performance of the wide area communicator32dynamically varies because the in-vehicle device3is used for a vehicle as a movable object. However, multiple periphery vehicles2bshare a similar communication environment with each other. An influence of the communication environment may change the communication performance of the wide area communicator32. In such a case, an influence of the communication environment also changes the reference value settled based on communication performance indexes acquired from the multiple periphery vehicles2b. Even if the wide area communicator32is abnormal, the anomaly exercises little influence on the reference value because multiple communication performance indexes are used. The reference value is therefore assumed to vary with the communication environment.

The reference value is compared with communication performance index for the wide area communicator32to determine an anomaly in the wide area communicator32of the periphery vehicle2b(S25). A difference between the reference value and the communication performance index is therefore large when the communication performance index for the wide area communicator32of the periphery vehicle2bindicates an abnormal value due to an anomaly of the wide area communicator32. A difference between the reference value and the communication performance index is not large when the wide area communicator32of the periphery vehicle2bis not abnormal but the communication performance index indicates an abnormal value due to an influence of the communication environment.

It is possible to accurately distinguish between the case where the wide area communicator32of the periphery vehicle2bis abnormal and the case where an influence of the communication environment causes an abnormal value from the communication performance index for the wide area communicator32. It is therefore possible to accurately determine anomaly of the wide area communicator32of the periphery vehicle2b.

The reference value is also used to determine anomaly of the wide area communicator32of the subject vehicle2a. Anomaly on the wide area communicator32of the subject vehicle2ais determined by comparing the reference value with the communication performance index for the wide area communicator32of the subject vehicle2a(S30). It is possible to accurately distinguish between the case where the wide area communicator32of the subject vehicle2ais abnormal and the case where an influence of the communication environment causes an abnormal value from the communication performance index for the wide area communicator32of the subject vehicle2afor the same reason as the above-mentioned anomaly determination on the wide area communicator32of the periphery vehicle2b. It is therefore possible to accurately determine anomaly of the wide area communicator32of the subject vehicle2a.

Particularly, the present embodiment does not perform the anomaly determination on the wide area communicator32when the area cannot satisfactorily receive a positioning signal (S22: NO). The positioning signal greatly degrades its communication performance in a tunnel similarly to the communication of the wide area communicator32. The reliability of the reference value is also highly likely to degrade in an area that cannot satisfactorily receive a positioning signal. It is therefore possible to suppress accuracy degradation in the anomaly determination by avoiding the anomaly determination on the wide area communicator32outside an area capable of satisfactorily receiving a positioning signal.

The present embodiment does not perform the anomaly determination on the wide area communicator32when located in a global roaming area (S23: YES). In the global roaming area, the wide area communicator32in the in-vehicle device3bmounted on multiple periphery vehicles2bis likely to perform a process that changes the wide area communication network6for connection to the wide area communication network6managed by a different telecommunications carrier. The communication performance temporarily degrades while this process is performed. All the periphery vehicles2bdo not perform the process to change the wide area communication network6even in the global roaming area. Some periphery vehicles2btemporarily degrade the communication performance, but others do not in the global roaming area. The reference value is therefore likely to be instable. It is therefore possible to suppress accuracy degradation in the anomaly determination by avoiding the anomaly determination on the wide area communicator32in the global roaming area.

Normally, the wide area communicator32is used for communication with the center5. The wide area communicator32, if abnormal, makes notification to the center5difficult. It is therefore difficult for the periphery vehicle2bincluding the abnormal wide area communicator32to notify the center5that the wide area communicator32of the periphery vehicle2bis abnormal.

However, the present embodiment determines that the wide area communicator32of the periphery vehicle2bis abnormal (S27: YES). In this case, the wide area communicator32of the subject vehicle2anotifies the center5of the vehicle ID of the periphery vehicle2bdetermined to be abnormal along with a message signifying that the wide area communicator32is abnormal (S28). The present embodiment can therefore notify the center5that the wide area communicator32is abnormal even if the wide area communicator32is abnormal. The center5can perform a process to temporarily stop a wide area communication service, when notified that the wide area communicator32is abnormal.

The present embodiment determines that the wide area communicator32of the subject vehicle2ais abnormal (S31: YES). In this case, the notifier38notifies that the wide area communicator32is abnormal (S32). An occupant of the subject vehicle2acan recognize that the wide area communicator32of the subject vehicle2ais abnormal. The occupant can use a communicator other than the wide area communicator32such as a mobile telephone carried by the occupant to notify the center5that the wide area communicator32of the subject vehicle2ais abnormal.

While the embodiment has been illustrated, the embodiment is not limited to the above-mentioned and can be variously modified. The embodiment is also applicable to the modifications described below. The description below includes an element assigned the same reference numeral as that used hitherto. Except as otherwise noted, such element equals the element that is assigned the same reference numeral and is described in the above-mentioned embodiment. A configuration may be described only partially. In such a case, the above-mentioned embodiment is applicable to the remaining part of the configuration.

The above-mentioned embodiment determines an anomaly on the wide area communicator32of the subject vehicle2a(S26, S27) and the wide area communicator32of the subject vehicle2b(S21through S23). However, anomaly may be determined on one of the wide area communicator32of the subject vehicle2aand the wide area communicator32of the subject vehicle2b.

In the above-mentioned embodiment, the subject vehicle2aand the periphery vehicle2bare mounted with the same in-vehicle device3. The controller37of the in-vehicle device3in each of the subject vehicle2aand the periphery vehicle2btherefore performs the information transmission process (FIG. 3), the information reception process (FIG. 4), and the anomaly determination process (FIGS. 5 and 6). However, the subject vehicle2aneed not perform the information transmission process (FIG. 3) so that the in-vehicle device3of the subject vehicle2adetermines an anomaly on the wide area communicator32of the subject vehicle2aand the periphery vehicle2b. The periphery vehicle2bneed not perform the information reception process (FIG. 4) and the anomaly determination process (FIG. 5). The controller37of the in-vehicle device3in the subject vehicle2atherefore may not perform the information transmission process (FIG. 3). The in-vehicle device3of the periphery vehicle2bmay not perform the information reception process (FIG. 4) and the anomaly determination process (FIG. 5).

The above-mentioned embodiment uses the narrow area communicator31to transmit the satellite signal quality index, the communication performance index, the present telecommunications carrier information, and the vehicle ID (S3). However, the wide area communicator32may be used to transmit the communication performance index and the others. In this case, the wide area communicator32also transmits the current position.

The wide area communicator32receives the communication performance index and the others when the wide area communicator32is used to transmit the communication performance index and the others. The wide area communicator32functions as a reception section. The wide area communicator32receives the communication performance index and the others from the vehicles other than the periphery vehicle2bwhen the wide area communicator32transmits and receives the communication performance index and the others. However, the communication performance index from the periphery vehicle2bcan be isolated from communication performance indexes received by the wide area communicator32based on the current position received along with the communication performance index and the current position of the subject vehicle2a. The wide area communicator32may therefore transmit and receive the communication performance index.

The position detector33may include an acceleration sensor and a gyro sensor in addition to the GNSS receiver so as to be capable of autonomous navigation when an electromagnetic wave is unsatisfactorily received from a positioning satellite.

As illustrated inFIG. 7, it may be determined that the wide area communicator32of the subject vehicle2ais abnormal (S31: YES). In this case, the narrow area communicator31of the subject vehicle2amay transmit request information to the narrow area communicator31mounted on the periphery vehicle2bor to the roadside device4(S33). The request information notifies the center5that the wide area communicator32of the subject vehicle2ais abnormal. Step S33corresponds to a third anomaly notification processing section. The narrow area communicator31of the subject vehicle2amay not be able to communicate with the narrow area communicator31of the periphery vehicle2band the roadside device4because the periphery vehicle2band the roadside device4are unavailable nearby. In such a case, a possible solution is to wait for a situation that enables communication with the periphery vehicle2bor the roadside device4.

Similarly to step S33inFIG. 7, the narrow area communicator31of the subject vehicle2amay be used when the in-vehicle device3aof the subject vehicle2anotifies the center5that the wide area communicator32of the periphery vehicle2bis abnormal. In this case, the narrow area communicator31corresponds to a specified communicator.

The above-mentioned embodiment causes the targeted wide area communicator to represent all the wide area communicator32whose reference value generation set includes the communication performance index. This embodiment is not limiting. The targeted wide area communicator may represent the predetermined number of wide area communicators32sequentially from the one nearest to the subject vehicle2aout of wide area communicators32whose reference value generation set includes the communication performance index.

The controller37may include a function as a baseband section that processes baseband signals included in electromagnetic waves transmitted and received by the wide area communicator32. In this case, the controller37specifies the communication performance index.

It may not be necessary to cyclically transmit the communication performance index. The communication performance index may be transmitted at the time when the narrow area communicator31starts communication with the roadside device4.

In the above-mentioned embodiment, the communication performance index corresponds to one of the RSSI, the average communication rate, the communication success rate, and the number of received error frames. The communication performance index may use two or more of these. In this case, the reference value is also specified for a respective communication performance index. The reference value is also compared with the communication performance index to determine an anomaly for a respective communication performance index. The anomaly determination performed for a respective communication performance index may result in the given number of communication performance indexes that satisfy an anomaly determination condition. The wide area communicator32corresponding to the communication performance index is then determined to be abnormal.