JP2023172797A - Wireless road-side machine, traffic communication system, and traffic communication method - Google Patents

Abstract

To provide a wireless road-side machine, a traffic communication system, and a traffic communication method that can properly detect antenna abnormality even when the wireless road-side machine has only one antenna.SOLUTION: A wireless road-side machine in one embodiment of the present invention is a wireless road-side machine 100 that performs road-vehicle communication with a vehicle 200 via an antenna 110. The wireless road-side machine 100 includes a radio reception unit 120 that receives a radio signal transmitted from the vehicle 200. The wireless road-side machine 100 includes a message processing unit 130 that obtains location information of the vehicle 200 from the radio signals. The wireless road-side machine 100 includes an RSSI estimation unit 140 that calculates a distance between the wireless road-side machine 100 and the vehicle 200 based on the location information, and estimates a first RSSI of the radio signal based on the distance. The wireless road-side machine 100 includes an RSSI operation unit 150 that measures a second RSSI of the radio signal. The road-side machine 100 includes an abnormality detecting unit 160 that detects an abnormality in the antenna 110 based on the first RSSI and the second RSSI.SELECTED DRAWING: Figure 5

Description

The present invention relates to a wireless roadside machine, a traffic communication system, and a traffic communication method.

In recent years, intelligent transport systems (ITS) have been attracting attention as a technology that can avoid the risk of traffic accidents. Non-Patent Document 1 defines standards for a traffic communication system that includes a wireless roadside device that is a base station installed on the roadside and an on-vehicle communication device that is a mobile station installed in a vehicle.

In transportation communication systems, for example, there are the following technologies. In other words, the wireless environment is monitored using an antenna that is not used for transmission among multiple antennas, and if the received power of the received packet signal is lower than a threshold value during the window period, it is determined that there is a transmission abnormality. There is a wireless device (for example, Patent Document 1 below).

On the other hand, in electronic toll collection systems (ETC), there are, for example, the following technologies. In other words, the roadside antenna is determined to be functioning properly based on whether the time period in which the received signal strength RSSI (Received Signal Strength Indication) of the radio waves received by the roadside antenna continues to be lower than a predetermined reception judgment threshold for a predetermined judgment reference time or more. There is also a toll collection system that determines whether or not it is operating (for example, Patent Document 2 below).

ARIB STD-T109 1.3 version “700MHz band intelligent transportation system”

Japanese Patent Application Publication No. 2013-5249 International Publication WO2017/145354 Publication

One aspect of the present invention is to provide a wireless roadside device, a traffic communication system, and a traffic communication method that can appropriately detect an antenna abnormality even when the number of antennas is one.

In the wireless roadside machine according to the first aspect, the base station is a wireless roadside machine that performs road-to-vehicle communication with a vehicle via an antenna. The wireless roadside machine includes a wireless receiver that receives wireless signals transmitted from a vehicle. Further, the wireless roadside machine includes a message processing unit that acquires vehicle position information from radio signals. Further, the wireless roadside device includes an RSSI estimator that calculates a distance between the wireless roadside device and the vehicle based on the position information, and estimates a first RSSI of the radio signal based on the distance. Further, the wireless roadside device includes an RSSI calculation unit that measures a second RSSI of the wireless signal. Further, the wireless lineside device includes an abnormality detection section that detects an abnormality in the antenna based on the first RSSI and the second RSSI.

The traffic communication system according to the second aspect includes the wireless roadside machine according to the first aspect.

The traffic communication method according to the third aspect is a traffic communication method performed by a wireless roadside device that performs wireless communication with a vehicle via an antenna. The transportation communication method includes the step of receiving a wireless signal transmitted from a vehicle. The traffic communication method also includes the step of acquiring vehicle position information from a radio signal. Further, the traffic communication method includes the steps of calculating the distance between the wireless roadside machine and the vehicle based on the position information, and estimating the first RSSI of the wireless signal based on the distance. Further, the traffic communication method includes the step of measuring a second RSSI of the radio signal. Further, the traffic communication method includes the step of detecting an abnormality in the antenna based on the first RSSI and the second RSSI.

According to one aspect, it is possible to provide a wireless roadside device, a traffic communication system, and a traffic communication method that can appropriately detect an antenna abnormality even when the number of antennas is one.

FIG. 1 is a diagram illustrating a configuration example of a transportation communication system according to a first embodiment. FIG. 2 is a diagram illustrating a configuration example of a vehicle according to the first embodiment. FIG. 3 is a diagram illustrating a configuration example of the wireless roadside machine according to the first embodiment. FIGS. 4A and 4B are diagrams illustrating examples of estimated RSSI according to the first embodiment. FIG. 5 is a diagram illustrating an example of operation according to the first embodiment. FIG. 6(A) is a diagram showing an example of location information according to the first embodiment, and FIG. 6(B) is a diagram showing an example of estimated RSSI according to the first embodiment. FIG. 7(A) is a diagram showing an example of position information according to the first embodiment, and FIG. 7(B) is a diagram showing an example of estimated RSSI according to the first embodiment. FIG. 8(A) is a diagram showing an example of map information according to the first embodiment, and FIG. 8(B) is a diagram showing an example of an internal estimation table according to the first embodiment. FIG. 9(A) is a diagram showing an example of position information according to the first embodiment, and FIG. 9(B) is a diagram showing an example of estimated RSSI according to the first embodiment. FIG. 10 is a diagram illustrating an example of estimated RSSI according to the first embodiment. FIG. 11 is a diagram illustrating an example of an internal estimation table according to the first embodiment. FIG. 12 is a diagram illustrating an example of an internal estimation table according to the first embodiment. FIG. 13(A) is a diagram showing an example of position information according to the first embodiment, and FIG. 13(B) is a diagram showing an example of estimated RSSI according to the first embodiment.

[First embodiment]
Wireless roadside devices using ITS transmit information important to traffic, such as signal information or information on pedestrians running out. When the on-vehicle communication device installed in the vehicle receives this information, the driver of the vehicle can understand the surrounding situation, supporting traffic safety by preventing the risk of traffic accidents. becomes possible.

In order to provide such information at any time, it is important for wireless lineside devices to promptly detect failures in their own stations. This is because prompt detection allows appropriate measures to be taken against failures, such as promptly replacing parts of the wireless trackside equipment.

One of the failures is an antenna abnormality. Antenna abnormality refers to a deterioration in antenna performance that is greater than originally expected due to a connection error during maintenance, failure due to contact with a flying object, or aging deterioration such as rust. An abnormality in the antenna may cause phenomena such as a reduction in the transmission power of the wireless signal transmitted from the wireless lineside device compared to a normal case. Therefore, the information that should be notified is not transmitted from the wireless roadside device to the vehicle, which may affect traffic safety.

In order to detect an antenna abnormality, for example, as in Patent Document 1, it is possible to monitor antenna abnormalities by using an antenna that is not used for transmission among a plurality of antennas.

However, in wireless roadside devices used in ITS, road-to-vehicle communication may be performed using a single antenna. In such a case, if one antenna is used for road-to-vehicle communication, there will be no unused antenna. Therefore, the technique of Patent Document 1 may not be able to appropriately detect an antenna abnormality.

It is also conceivable to use a plurality of antennas, measure the RSSI of a radio signal received by each antenna, and detect an antenna abnormality based on the difference in RSSI between the antennas.

However, as described above, when road-to-vehicle communication is performed using a wireless roadside device having one antenna, the antenna abnormality detection technique using multiple antennas cannot be used.

Furthermore, for example, as in Patent Document 2, it is also possible to detect an abnormality in the roadside antenna by comparing the received signal strength (RSSI) of the radio waves received by the roadside antenna with a predetermined reception determination threshold.

However, if only the received signal strength (RSSI) of the radio waves received by the roadside antenna is the subject of judgment, depending on the situation around the roadside antenna, such as the presence of obstacles around the roadside antenna, even though there is no abnormality in the antenna, , the received signal strength (RSSI) may be smaller than a predetermined reception determination threshold.

Therefore, the technique of Patent Document 2 may not be able to appropriately detect antenna abnormalities.

Therefore, in the first embodiment, it is an object of the present invention to make it possible to appropriately detect an antenna abnormality even in a wireless lineside device having only one antenna.

A traffic communication system according to an embodiment will be described below with reference to the drawings. In addition, in the description of the following drawings, the same or similar parts are given the same or similar symbols.

(Example of configuration of transportation communication system)
First, a configuration example of a traffic communication system according to an embodiment will be described. In the following, a transportation communication system that performs wireless communication based on the standard of Non-Patent Document 1 will be mainly explained, but it is not limited to this standard. Wireless communication based on the V2X (Vehicle to Everything) standard of .) may be performed.

FIG. 1 is a diagram illustrating a configuration example of a traffic communication system 10 according to an embodiment. As shown in FIG. 1, the traffic communication system 10 includes a wireless roadside machine 100 provided near a road and a vehicle 200 running on the road.

The wireless roadside machine 100 is installed near a road. In the example shown in FIG. 1, the wireless roadside machine 100 is installed on a support (or utility pole) provided near a road. The wireless roadside device 100 may be installed in a traffic signal light device (for example, a traffic light). Wireless lineside machine 100 is connected to server device 300 via a communication line. Server device 300 is sometimes called a central device. The server device 300 collects various types of traffic information based on the information received by the wireless roadside machine 100 and manages road traffic.

Vehicle 200 may be any vehicle that travels on a road. The vehicle 200 may be, for example, a car such as a regular car or a light car, or a motorcycle (motorcycle). Additionally, vehicle 200 may be an autonomous vehicle. The vehicle 200 is provided with an in-vehicle communication device 250. In-vehicle communication device 250 may be a stationary communication device that is fixedly provided on vehicle 200, or may be a portable communication device that is temporarily connected to vehicle 200 via a cable.

In addition, in the traffic communication system 10 shown in FIG. 1, one wireless roadside machine 100 and one vehicle 200 are illustrated, but there may be a plurality of wireless roadside machines 100, and the vehicle 200 may also be present. There may be multiple units.

In such a traffic communication system 10, road-to-vehicle communication is performed between the wireless roadside device 100 and the vehicle-mounted communication device 250, and vehicle-to-vehicle communication is performed between the vehicle-mounted communication devices 250. In one embodiment, the in-vehicle communication device 250 shares a carrier wave frequency (frequency band) in the 700 MHz band with the wireless roadside device 100 in a time-sharing manner.

For example, through road-to-vehicle communication, the in-vehicle communication device 250 receives a road-to-vehicle message sent from the wireless roadside device 100, and the wireless roadside device 100 receives a vehicle information message sent from the in-vehicle communication device 250. Further, through vehicle-to-vehicle communication, a vehicle information message transmitted from one vehicle-mounted communication device 250 is received by another vehicle-mounted communication device 250. Through road-to-vehicle communication and vehicle-to-vehicle communication, it is possible to recognize the status of surrounding vehicles, traffic information, the presence or absence of pedestrians, and provide support to avoid the risk of traffic accidents. Further, the vehicle information message received by the wireless roadside machine 100 can be used for smoothing traffic flow, etc.

The road-to-vehicle message is a message that includes information regarding the road. Road-to-vehicle messages are based on, for example, the ``ITS Wireless Lineside Equipment Communication Application Common Standards'' and the ``5.8GHz/700MHz Band Wireless DSSS Communication Application (Optical/Radio Wave Experiment) Standards,'' published by the UTMS (Universal Traffic Management System) Association. It has a predetermined format compliant with .

The vehicle information message is a message containing information regarding vehicle 200. The vehicle information message has, for example, a predetermined format based on the "ITS Connect System Vehicle-to-Vehicle Communication Message Specification" published by the ITS Connect Promotion Council. Such a format may be "ITS Connect TD-001 version 1.0".

Furthermore, in the traffic communication system 10, roadside communication may be performed between the wireless roadside machines 100. Through road-to-road communication, a road-to-road message transmitted from one wireless roadside machine 100 is received by another wireless roadside machine 100.

Broadcast wireless communication may be used for each of the road-to-vehicle communication, vehicle-to-vehicle communication, and road-to-road communication. For example, only a broadcast address may be defined as a destination address (destination MAC address) for a wireless signal (communication packet) to be transmitted. Road-to-vehicle communication, vehicle-to-vehicle communication, and road-to-road communication are performed in a time-sharing manner so as not to overlap each other.

(Road-to-vehicle communication)
In road-to-vehicle communication, a road-to-vehicle communication period is assigned to the wireless roadside machine 100. The road-to-vehicle communication period is set at a maximum of 390 units (6240 μs) from the beginning of the control cycle during a 100 ms cycle (called a “control cycle”), with 16 μs as one control unit (called a “unit”). 16'' can be set. The wireless roadside device 100 broadcasts a road-to-vehicle message at a predetermined period using the road-to-vehicle communication period assigned to itself.

The road-to-vehicle message includes information regarding the road-to-vehicle communication period. Specifically, the wireless roadside device 100 transmits (notifies) a road-to-vehicle message that includes transmission time and road-to-vehicle communication period information (number of transfers and road-to-vehicle communication period length) as its own transmission information to the surrounding vehicle-mounted communication devices 250. ) to secure their own transmission time.

The in-vehicle communication device 250 that receives such a road-to-vehicle message synchronizes its time based on the transmission time included in the road-to-vehicle message, and stops its own transmission based on the road-to-vehicle communication period information included in the road-to-vehicle message. , the transmission is performed at a timing other than the transmission period of the wireless lineside machine 100. Specifically, the on-vehicle communication device 250 uses CSMA/CA (Carrier Sense Multiple Access /Collision Avoidance) method to broadcast vehicle information messages. The CSMA/CA system is a communication system that avoids contention when multiple users access the same channel. The CSMA/CS method is adopted as a communication protocol in IEEE802.11Aa, IEEE802.11b, and IEEE802.11g.

In the first embodiment, the wireless roadside device 100 receives the vehicle information message transmitted by the on-vehicle communication device 250, and the wireless roadside device 100 includes the vehicle information message based on the position information included in the vehicle information message. Estimate the RSSI when receiving a wireless signal. Then, the wireless roadside device 100 uses the estimated RSSI (hereinafter sometimes referred to as "estimated RSSI") and the RSSI measured when receiving the radio signal (hereinafter sometimes referred to as "measured RSSI"). An abnormality in the antenna of the wireless lineside device 100 is detected based on the following.

Specifically, first, the wireless trackside machine 100 calculates the distance between the wireless trackside machine and the vehicle based on the position information included in the vehicle information message (or radio signal), and calculates the distance between the radio trackside machine and the vehicle based on the distance. , estimate the RSSI (first RSSI) of the radio signal. Second, the wireless lineside device 100 measures the RSSI (second RSSI) when receiving the wireless signal. Thirdly, the wireless lineside device 100 detects an abnormality in the antenna based on the estimated RSSI and the measured RSSI.

As a result, for example, since the RSSI is estimated from the position information of the vehicle 200, the accuracy of the estimated RSSI may be higher than the measured RSSI, and antenna abnormalities are detected based on such estimated RSSI and measured RSSI. By doing so, it becomes possible to appropriately detect an antenna abnormality even if there is only one antenna.

(Example of vehicle configuration)
Next, a configuration example of the vehicle 200 according to the first embodiment will be described.

FIG. 2 is a diagram illustrating a configuration example of vehicle 200.

As shown in FIG. 2, vehicle 200 includes a GNSS (Global Navigation Satellite System) receiving section 210, a message generating section 220, a wireless transmitting section 230, and an antenna 240.

GNSS receiving section 210 performs positioning based on GNSS satellite signals received from satellites, and outputs position information indicating the current geographical position (latitude and longitude) of vehicle 200 to message generating section 220. The GNSS receiving unit 210 is configured to use, for example, GPS (Global Positioning System), GLONASS (Global Navigation Satellite System), IRNSS (Indian Regional Navigation Satellite System), COMPASS (Compass Navigation Satellite System), Galileo, and QZSS (Quasi-Zenith Satellite System). The system includes at least one GNSS receiver.

Message generating section 220 generates a vehicle information message including location information, and outputs the generated vehicle information message to wireless transmitting section 230 . The vehicle information message may be a message shown in "ITS Connect TD-001 Version 1.0". The vehicle information message may include various information other than location information. For example, the vehicle information message may include at least one of speed information representing the speed of vehicle 200, azimuth information representing the traveling direction of vehicle 200, and type information representing the type of vehicle 200. The message generation unit 220 may obtain speed information from a speed meter (or speed sensor) provided in the vehicle 200, or the like. Additionally, the message generation unit 220 may acquire orientation information from the GNSS reception unit 210. Furthermore, the message generation unit 220 may acquire the type information by reading the type information stored in a memory inside the vehicle 200 from the memory. The message generation unit 220 may generate a vehicle information message including the information acquired in this way.

The wireless transmitter 230 performs signal processing on the vehicle information message received from the message generator 220 to convert (upconvert) the vehicle information message into a wireless signal in a wireless band. The wireless transmitting unit 230 performs the above-mentioned road-to-vehicle communication, that is, the road-to-vehicle communication using a wireless communication method compliant with ARIB (Association of Radio Industries and Businesses) STD-T109. However, the wireless transmitter 230 may use a method compliant with the 3GPP V2X standard. In the case of ARIB STD-T109, the wireless transmission unit 230 performs transmission at a timing other than the transmission period of the wireless roadside device 100 based on the road-to-vehicle communication period information included in the road-to-vehicle message already received from the wireless roadside device 100. . At this time, the wireless transmitter 230 performs carrier sense, determines the availability of a radio wave frequency (for example, 700 MHz band), and broadcasts a wireless signal at a timing determined according to the result of the carrier sense. Good too.

Antenna 240 transmits the wireless signal received from wireless transmitter 230.

Note that the vehicle 200 is provided with an on-vehicle communication device 250. The in-vehicle communication device 250 includes a GNSS receiving section 210, a message generating section 220, a wireless transmitting section 230, and an antenna 240.

(Example of configuration of wireless trackside machine)
Next, a configuration example of the wireless roadside machine 100 according to the first embodiment will be described.

FIG. 3 is a diagram showing a configuration example of the wireless roadside machine 100.

As shown in FIG. 3, the wireless roadside device 100 includes an antenna 110, a wireless reception section 120, a message processing section 130, an RSSI estimation section 140, an RSSI calculation section 150, an abnormality detection section 160, and an abnormality notification section. 170.

Antenna 110 receives a wireless signal transmitted from vehicle 200 (or vehicle-mounted communication device 250). Antenna 110 outputs the received radio signal to radio receiving section 120. Note that the number of antennas 110 may be one or more than one.

Radio receiving section 120 performs road-to-vehicle communication with vehicle 200 via antenna 110. It is assumed that the wireless communication method in the wireless receiving section 120 is a method based on ARIB STD-T109. However, the wireless receiving unit 120 may be of a system compliant with the 3GPP V2X standard.

Radio receiving section 120 receives a radio signal transmitted from vehicle 200 via antenna 110. The wireless receiving unit 120 performs signal processing on the wireless signal to convert (down-convert) the wireless signal in the wireless band to the baseband signal in the baseband band. Wireless receiving section 120 outputs the baseband signal to message processing section 130.

Message processing section 130 extracts a vehicle information message from the baseband signal received from wireless receiving section 120, and acquires position information of vehicle 200 from the vehicle information message. That is, the message processing unit 130 acquires the position information of the car 200 from the wireless signal via the wireless reception unit 120. The message processing unit 130 outputs the acquired location information to the RSSI estimation unit 140. Note that the message processing unit 130 may obtain at least one of the speed information of the vehicle 200, the direction information of the vehicle 200, and the type information of the vehicle 200 in addition to the position information from the vehicle information message (or radio signal). good. Additionally, the message processing unit 130 may acquire the MAC address from the vehicle information message (or wireless signal). Message processing section 130 outputs location information to RSSI estimating section 140. The message processing unit 130 may output at least one of the speed information of the vehicle 200, the direction information of the vehicle 200, the type information of the vehicle 200, and the MAC address to the RSSI estimation unit 140.

The RSSI estimation unit 140 calculates the distance between the wireless roadside machine 100 and the vehicle 200 based on the position information. For example, the RSSI estimation unit 140 uses the position information received from the message processing unit 130 (that is, the latitude and longitude of the current position of the vehicle 200) and the position information of the wireless roadside machine 100 read from the memory in the wireless roadside machine 100 ( That is, the distance between the wireless trackside machine 100 and the vehicle 200 is calculated based on the latitude and longitude of the position where the wireless trackside machine 100 is installed. Then, the RSSI estimation unit 140 estimates the RSSI of the wireless signal based on the distance.

In the wireless roadside device 100, there is a correlation between the RSSI of the received radio signal and the distance from the transmission source (that is, the vehicle 200 or the vehicle-mounted communication device 250) that transmitted the wireless signal to the wireless roadside device 100. That is, the shorter the distance, the higher the RSSI, and the farther the distance, the lower the RSSI. The RSSI estimator 140 obtains the RSSI corresponding to the distance based on a table or function representing such a correlation on the premise that the transmission power of the radio signal transmitted from the vehicle 200 is known. , this may be used as the estimated RSSI. RSSI estimation section 140 outputs the estimated RSSI to abnormality detection section 160. Note that the wireless roadside device 100 may directly acquire the transmission power from the vehicle 200, or may store it in a memory or the like in advance.

RSSI calculation section 150 measures the RSSI of the radio signal received by radio reception section 120. The RSSI calculation unit 150 may measure the RSSI of a wireless signal in a wireless band. In this case, the RSSI calculation section 150 may obtain the measured RSSI measured by the radio reception section 120 from the radio reception section 120. RSSI calculation section 150 outputs the measured RSSI to abnormality detection section 160.

The abnormality detection unit 160 detects an abnormality in the antenna 110 based on the estimated RSSI (first RSSI) and the measured RSSI (second RSSI). Specifically, the abnormality detection unit 160 determines that the antenna 110 has an antenna abnormality when the number of times the difference between the estimated RSSI and the measured RSSI is equal to or greater than the first threshold (consecutively) exceeds the second threshold. do. On the other hand, if the difference between the estimated RSSI and the measured RSSI is less than the first threshold, and even if the difference is greater than or equal to the first threshold, the abnormality detection unit 160 detects that the number of times (consecutively) is less than or equal to the second threshold. In at least one of these cases, it is determined that the antenna 110 is normal. The abnormality detection section 160 outputs the detection result to the abnormality notification section 170.

The abnormality notification unit 170 transmits the detection result from the abnormality detection unit 160 to the server device 300. Then, via the server device 300, it becomes possible to notify, for example, the administrator who manages the traffic communication system 10 of an abnormality in the antenna of the wireless roadside device 100.

FIG. 4A is a diagram illustrating measured RSSI and estimated RSSI in time series in a case where position information is transmitted from a stopped vehicle 200 (or in-vehicle communication device 250). In FIG. 4(A), "ANT" represents the measured RSSI.

As shown in FIG. 4(A), an example in which the measured RSSI changes from "-70 dB" to "-110 dB" is shown. For example, if the first threshold is "-10 dB" and the second threshold is "6 times", if the measured RSSI is "-70 dB", the difference from the estimated RSSI is "-5 dB", which is less than the first threshold. It becomes. Therefore, the abnormality detection unit 160 determines that the antenna is normal (“OK”). On the other hand, when the measured RSSI is "-110 dB", the difference from the estimated RSSI is "-35 dB", and the difference is greater than or equal to the first threshold. Then, when the number of times the difference is detected as being equal to or greater than the first threshold value is "seven times" consecutively, the number of times exceeds the second threshold value, so the abnormality detection unit 160 determines that the antenna 110 is abnormal. In the example of FIG. 4(A), the abnormality notification unit 170 transmits a warning message to the server device 300 based on the determination result.

FIG. 4B shows an example of measured RSSI (“ANT”) and estimated RSSI in a case where vehicle 200 approaches wireless roadside machine 100 over time. As shown in FIG. 4(B), until the measured RSSI reaches "-62 dB", the difference from the estimated RSSI is less than or equal to the first threshold ("-10 dB"). Therefore, the abnormality detection unit 160 determines that the antenna 110 is normal. On the other hand, after that, when the measured RSSI becomes "-110 dB", the difference from the estimated RSSI becomes equal to or greater than the first threshold. Therefore, the abnormality detection unit 160 determines that the difference is equal to or greater than the first threshold (“NG”). Then, the abnormality detection unit 160 determines that there is an antenna abnormality when the number of times the difference is equal to or greater than the first threshold exceeds the second threshold ("six times").

(Operation example in the first embodiment)
Next, an example of operation according to the first embodiment will be described.

FIG. 5 is a diagram illustrating an example of operation according to the first embodiment. In addition, below, the vehicle 200 and the vehicle-mounted communication device 250 may be used without distinction. For example, location information transmitted from vehicle 200 and location information transmitted from in-vehicle communication device 250 may be described as having the same meaning.

As shown in FIG. 5, in step S10, vehicle 200 acquires position information.

In step S11, vehicle 200 transmits position information. For example, the wireless transmitter 230 transmits a wireless signal (or vehicle information message) including location information indicating the local location of the vehicle 200.

In step S12, the wireless roadside machine 100 receives the radio signal and measures the RSSI of the radio signal. For example, the RSSI calculation unit 150 measures the RSSI of the wireless signal received by the wireless reception unit 120.

In step S13, the wireless roadside machine 100 estimates RSSI from the position information. For example, the message processing unit 130 acquires position information from the wireless signal, and the RSSI estimating unit 140 calculates the distance between the wireless roadside machine 100 and the vehicle 200 from the position information, and estimates the RSSI from the distance.

In step S14, the wireless roadside device 100 (abnormality detection unit 160) detects an abnormality in the antenna 110 based on the measured RSSI (step S12) and the estimated RSSI (step S13).

(First modification of the first embodiment)
Next, a first modification of the first embodiment will be described. In the first modified example, differences from the first embodiment will be mainly explained.

For example, consider a case where visibility is good in front of the wireless trackside machine 100, but visibility is not good in the rear due to the presence of pillars or the like. In such a case, in the wireless roadside machine 100, although the measured RSSI for the front has a value close to the estimated RSSI, the measured RSSI for the rear may differ from the estimated RSSI by more than the third threshold value. In such a case, even if the wireless roadside device 100 estimates the estimated RSSI based on the radio signal from behind, the difference between the estimated RSSI and the measured RSSI is greater than the third threshold, so the wireless roadside device 100 detects an abnormality in the antenna 110. It may not be possible to detect it properly.

Therefore, in the first modification, an example will be described in which the estimated RSSI is learned using the measured RSSI. That is, the abnormality detection unit 160 corrects the estimated RSSI when the difference between the estimated RSSI (first RSSI) and the measured RSSI (second RSSI) is equal to or greater than the threshold (third threshold) within the correction period, and then corrects the estimated RSSI after the correction period has elapsed. , an abnormality in the antenna 110 is detected based on the corrected estimated RSSI and measured RSSI.

In this way, the wireless roadside machine 100 corrects the estimated RSSI based on the measured RSSI within the correction period, so that the estimated RSSI is brought closer to the measured RSSI until the difference from the measured RSSI becomes less than the third threshold. It is also possible to do so. Therefore, it is possible to set the estimated RSSI to a value that corresponds to the surrounding situation of the wireless trackside device 100, and after the correction period has elapsed, the wireless trackside device 100 can appropriately determine whether an abnormality has been detected in the antenna 110. .

FIG. 6(A) shows the time series of location information, measured RSSI, and distance in a case where location information is transmitted from a vehicle 200 located at the same location (latitude is "35.001" and longitude is "135.001"). It is expressed as Further, FIG. 6(B) shows an example of the estimated RSSI and the corrected estimated RSSI in time series. Note that the wireless trackside machine 100 is installed at a position with a latitude of "35" and a longitude of "135".

In this case, as shown in FIG. 6(A), the measured RSSI was "-80 dB". On the other hand, when the estimated RSSI was calculated based on the position information acquired from the vehicle 200, it was "-75 dB" as shown in FIG. 6(B). Assuming that the difference between the measured RSSI ("80 dB") and the estimated RSSI ("-75 dB") is greater than or equal to the third threshold (eg, "5 dB"), the abnormality detection unit 160 corrects the estimated RSSI. For example, the abnormality detection unit 160 performs the correction using the following equation.

Estimated RSSI after correction = estimated RSSI + (measured RSSI - estimated RSSI) x 0.1 (1)

As a result, as shown in FIG. 6(B), the estimated RSSI after correction is "75.500". Thereafter, the abnormality detection unit 160 calculates the equation (1) each time position information is obtained from the vehicle 200, using the corrected estimated RSSI as the "estimated RSSI", and calculates the corrected estimated RSSI within the correction period. Repeat the calculation. As a result, the estimated RSSI is learned. The correction period may be a learning period or a training period. Then, when the correction period ends, the abnormality detection unit 160 obtains "-79.392 dB" as the estimated RSSI, as shown by the dotted line in FIG. 6(B). Thereafter, the abnormality detection unit 160 uses the corrected estimated RSSI (“-79.392 dB”) as the “estimated RSSI” and compares the “estimated RSSI” with the measured RSSI to determine whether an abnormality has been detected in the antenna 110.

As for the operation of the first modified example, for example, in step S13 of FIG. 5, the abnormality detection unit 160 performs a correction process using equation (1) within the correction period, so that the estimated RSSI after correction is The estimated RSSI may be obtained as the "estimated RSSI".

Note that equation (1) is just an example, and any calculation equation that brings the estimated RSSI closer to the measured RSSI may be used. For example, "0.1" on the right side of equation (1) may be replaced with "0.1". It may be set to ``.15'' or ``0.2''.

Furthermore, when determining an abnormality in the antenna 110 within the correction period, the abnormality detection unit 160 may use the corrected RSSI as appropriate. For example, if the corrected RSSI when determining the abnormality of the antenna 110 is "-79.073 dB", the abnormality detection unit 160 uses this "-79.073 dB" as the estimated RSSI and detects the abnormality of the antenna 110. You may judge.

Furthermore, in FIG. 6(B), an internal table is used. For example, the abnormality detection unit 160 may store an internal table in a memory within the wireless roadside machine 100, and use the internal table to calculate the corrected RSSI. Further, the abnormality detection unit 160 may hold the corrected RSSI in an internal table, read the corrected RSSI from the internal table as appropriate, and determine whether the antenna 110 is abnormal.

(Second modification of the first embodiment)
Next, a second modification of the first embodiment will be described. The second modification will also be explained mainly focusing on the differences from the first embodiment.

As explained in the first modification, even if the vehicles 200 are located at the same distance from the wireless trackside machine 100, the (measured) RSSI may differ depending on the situation around the wireless trackside machine 100. For example, in a case where the north direction of the wireless roadside machine 100 is a downhill slope and the south direction is flat, the RSSI from the north direction may be lower than the RSSI from the south direction even at the same distance. Furthermore, for example, in a case where there is a pillar behind the wireless trackside machine 100 in the east direction and visibility in the west direction is good, the RSSI from the east direction may be lower than the RSSI from the west direction due to the influence of the pillar. .

Therefore, in a second modification, an example will be described in which directions such as east, west, north, south, etc. are acquired from position information and the estimated RSSI is estimated by taking the directions into consideration. Specifically, the RSSI estimating unit 140 calculates the direction of the vehicle 200 with respect to the wireless trackside machine 100 based on the position information, and estimates the RSSI (first RSSI) based on the direction and distance.

As a result, for example, the wireless roadside machine 100 can obtain an estimated RSSI according to the surrounding situation, and by making an abnormality determination using such an estimated RSSI, an abnormality determination of the antenna 110 can be appropriately performed. be able to.

FIG. 7(A) shows an example of location information, and FIG. 7(B) shows an example of estimated RSSI. 7(A) and 7(B) show an example of a case where the wireless roadside machine 100 is installed at a longitude of "35" and a latitude of "135".

FIG. 7A shows an example of a case where the latitude "35.001" remains unchanged and the longitude changes, that is, the vehicle 200 moves in the east-west direction. In the example shown in FIG. 7(A), the measured RSSI at each position with the longitude "135" as the center and the same distance to the wireless trackside device 100 is the same value, although the longitude is different. There is.

For example, the longitude "135.0005" and the longitude "134.9995" have the same distance to the wireless trackside device 100, and the measured RSSI of the former is "-77.9 dB" and the measured RSSI of the latter is "-77 dB." .9dB". Therefore, the estimated RSSI shown in FIG. 7(B) also has the same numerical value, ie, the former estimated RSSI is "-72.6 dB" and the latter estimated RSSI is "-72.6 dB."

Similarly, for example, the longitude "135.0001" and the longitude "134.9999" have the same distance to the wireless lineside device 100, the measured RSSI for both is "-77.1 dB", and the estimated RSSI is also , both are "-71.8 dB".

As mentioned above, depending on the situation around the wireless roadside machine 100, the measured RSSI may differ depending on the east-west direction even at the same distance. In such a case, the estimated RSSI may also vary depending on the measured RSSI even at the same distance in the east-west direction. It can be a different number. FIG. 7(A) and FIG. 7(B) represent an example in which the estimated RSSI is the same at the same distance.

For example, the RSSI estimation unit 140 calculates the distance from the position information, estimates the RSSI from the distance, and then corrects the estimated RSSI according to the direction using a predetermined calculation formula for the estimated RSSI. Different "estimated RSSI" can be obtained depending on the direction.

(Third modification of the first embodiment)
Next, a third modification of the first embodiment will be described. The third modification will also be explained mainly focusing on the differences from the first embodiment.

The third modification is an example using map information. As described above, the estimated RSSI can be calculated from the distance. Therefore, it is possible to calculate the distance to the wireless roadside device 100 using the latitude and longitude included in the map information, and also calculate the estimated RSSI from the distance. Thereby, for example, the wireless roadside machine 100 can obtain estimated RSSI with higher resolution regarding position information, compared to the case where position information acquired from the vehicle 200 is used.

FIG. 8(A) shows an example of map information, and FIG. 8(B) shows an example of estimated RSSI. Each estimated RSSI in FIG. 8(B) is transmitted from the vehicle 200 to the wireless roadside device 100 when it is assumed that the vehicle 200 is located at each position on the road indicated by diagonal lines in FIG. 8(A). Represents an estimate of the RSSI of a wireless signal.

As shown in FIG. 8(B), the RSSI estimation unit 140 stores each estimated RSSI in an internal estimation table based on the map information. The internal estimation table is a table representing the correspondence between position information and estimated RSSI. Then, the RSSI estimation unit 140 uses the internal estimation table to obtain the estimated RSSI corresponding to the position information. Specifically, the RSSI estimation unit 140 performs the following processing.

That is, the RSSI estimation unit 140 calculates the distance between the wireless trackside machine 100 and the position indicated by the position information, based on the position information acquired from the map information. The RSSI estimation unit 140 calculates the estimated RSSI based on the distance, and stores the estimated RSSI in an internal estimation table. The RSSI estimation unit 140 stores an internal estimation table in the memory within the wireless roadside machine 100. The RSSI estimation unit 140 uses the internal estimation table to obtain the estimated RSSI corresponding to the location information obtained by the message processing unit 130. RSSI estimation section 140 outputs the obtained estimated RSSI to abnormality detection section 160. Thereafter, abnormality detection of the antenna 110 is performed in the same manner as in the first embodiment.

(Fourth modification example according to the first embodiment)
Next, a fourth modification of the first embodiment will be described.

In the first modification, an example has been described in which the wireless roadside machine 100 corrects the estimated RSSI within the correction period. On the other hand, when the traveling speed of vehicle 200 is equal to or higher than the predetermined speed, the accuracy of RSSI or the accuracy of position information may deteriorate compared to when the traveling speed of vehicle 200 is less than the predetermined speed.

Therefore, in the fourth modification, the estimated RSSI is corrected in consideration of the vehicle speed. Specifically, first, the message processing unit 130 acquires the speed of the vehicle 200 from the wireless signal (or vehicle information message) transmitted from the vehicle 200. Second, RSSI estimating section 140 does not correct the estimated RSSI when the speed of vehicle 200 is equal to or higher than a predetermined speed.

Thereby, for example, the wireless roadside machine 100 can obtain the estimated RSSI after correction according to the accuracy of the RSSI based on the traveling speed of the vehicle 200 or the accuracy of the position information. Therefore, in the wireless lineside machine 100, it becomes possible to appropriately determine the abnormality of the antenna 110.

Furthermore, since the wireless trackside device 100 can obtain the speed (or speed information) of the vehicle 200 from the vehicle information message, the first threshold value used when determining antenna abnormality is changed according to the speed. Good too.

For example, the abnormality detection unit 160 may acquire the speed of the vehicle 200 from the message processing unit 130, and when the speed is equal to or higher than a predetermined speed, the abnormality detection unit 160 may change the first threshold to a larger value as the “first threshold”. . Then, the abnormality detection unit 160 determines that the antenna 110 is normal when the difference between the measured RSSI and the estimated RSSI is equal to or less than the "first threshold" after the change. Further, the abnormality detection unit 160 determines that the antenna 110 is abnormal when the number of times the difference exceeds the changed "first threshold" exceeds the second threshold. When the speed of vehicle 200 is equal to or higher than the predetermined speed, the measured RSSI becomes larger than when the speed is less than the predetermined speed. Therefore, the abnormality detection unit 160 determines whether the antenna 110 is abnormal using a "first threshold" that takes such measured RSSI into consideration. Therefore, in the wireless line side machine 100, it becomes possible to appropriately determine an antenna abnormality.

On the other hand, when the speed of vehicle 200 is less than a predetermined speed, a value that is smaller than the first threshold may be changed to the "first threshold". In this case as well, the abnormality detection unit 160 can appropriately determine the antenna abnormality as in the case where the first threshold value is made larger.

FIG. 9(A) shows an example of position information, and FIG. 9(B) shows an example of estimated RSSI after correction. As shown in FIG. 9(B), when the speed is equal to or higher than a predetermined speed (for example, "30" km/h), the estimated RSSI is not corrected and is left blank in the internal table.

(Fifth modification example of the first embodiment)
Next, a fifth modification example of the first embodiment will be described. The fifth modification will also be explained mainly focusing on the differences from the first embodiment.

The fifth modification is an example in which the wireless roadside machine 100 calculates the estimated RSSI in consideration of the traveling direction of the vehicle 200.

For example, consider a case where the vehicle 200 moves from north to south with respect to the wireless roadside machine 100. In such a case, assuming that the on-board communication device 250 of the vehicle 200 is installed in front of the vehicle 200, the wireless roadside device 100 can calculate the measured RSSI when the vehicle 200 approaches from the north, and the measured RSSI when the vehicle 200 approaches from the north. The measured RSSI when moving farther south may differ even if the radio signals are from the same distance.

That is, when the on-board communication device 250 is provided in front of the vehicle 200, when the vehicle 200 approaches the wireless trackside device 100, the vehicle 200 itself transmits the wireless signal transmitted from the on-board communication device 250 to the wireless trackside device 100. reach. On the other hand, when the vehicle 200 moves away from the wireless roadside machine 100, the wireless signal reaches the wireless roadside machine 100 via the vehicle 200. Therefore, when the vehicle 200 is farther away from the wireless trackside machine 100 by passing through the vehicle 200, compared to when the vehicle 200 approaches from the wireless trackside machine 100, even if the distance is the same, the RSSI of the radio signal is becomes lower.

In the fourth modification, the wireless roadside machine 100 uses different estimated RSSIs depending on the direction of travel of the vehicle, such as when the vehicle 200 approaches the wireless roadside machine 100 and when the vehicle 200 moves away from the wireless roadside machine 100. An example of how to do this will be explained below.

Specifically, first, the message processing unit 130 acquires the direction (or direction information) of the vehicle 200 from the wireless signal. Second, the RSSI estimation unit calculates the traveling direction of the vehicle 200 with respect to the wireless roadside machine 100 from the direction of the vehicle 200, and estimates the RSSI (first RSSI) based on the distance and the traveling direction.

Thereby, in the wireless roadside machine 100, it becomes possible to appropriately determine the abnormality of the antenna 110 based on the estimated RSSI according to the traveling direction of the vehicle.

FIG. 10 is a diagram illustrating an example of an internal estimation table. FIG. 10 shows an example of estimated RSSI according to the traveling direction of vehicle 200. However, in the example of FIG. 10, when the distance is the same when the vehicle 200 approaches and when the vehicle 200 moves away from the position of the wireless roadside machine 100 (latitude "35", longitude "135") , and the estimated RSSI are the same.

As described above, if the distance is the same when the vehicle 200 approaches and when the vehicle 200 moves away, the estimated RSSI may take different values. For example, if the distances are the same when the vehicle 200 approaches and when the vehicle 200 moves away, the RSSI estimation unit 140 uses a predetermined calculation formula to estimate the estimated RSSI so that the latter has a lower estimated RSSI than the former. The "estimated RSSI" may be obtained by correcting the RSSI.

Note that the wireless roadside device 100 may obtain the estimated RSSI using an internal estimation table, similarly to the third modification.

(Sixth modification example according to the first embodiment)
Next, a sixth modification example of the first embodiment will be described. The sixth modification will also be explained mainly focusing on the differences from the first embodiment.

For example, the height from the ground at which the in-vehicle communication device 250 is installed may be different depending on whether the vehicle 200 is a truck or a car. Due to this difference in height, the RSSI value measured by the wireless roadside device 100 may also differ.

Therefore, in the sixth modification, the wireless roadside machine 100 calculates the estimated RSSI in consideration of the type of vehicle 200. Specifically, first, the message processing unit 130 acquires the type of vehicle from the wireless signal. Second, the RSSI estimation unit 140 estimates the RSSI (first RSSI) based on the distance and type.

As a result, for example, the wireless trackside device 100 detects an antenna abnormality using the estimated RSSI according to the installation position of the in-vehicle communication device 250 depending on the type of vehicle 200, so that it is possible to appropriately detect an antenna abnormality. becomes.

FIG. 11 is a diagram illustrating an example of an internal estimation table. FIG. 11 is a diagram showing an example of estimated RSSI for a passenger car and a truck. However, the example in FIG. 11 represents an example in which the estimated RSSI values are the same for a passenger car and a truck when the distances are the same. After calculating the estimated RSSI from the position information, the RSSI estimation unit 140 may obtain the estimated RSSI according to the type of the vehicle 200 by correcting the estimated RSSI using a predetermined calculation formula.

(Seventh modification example according to the first embodiment)
Next, a seventh modification of the first embodiment will be described. The seventh modification will also be explained mainly focusing on the differences from the first embodiment.

The in-vehicle communication device 250 may exhibit different behavior depending on the manufacturer that manufactures the in-vehicle communication device 250. Therefore, the measured RSSI of the in-vehicle communication device 250 may differ depending on the manufacturer even if the distance is the same.

Therefore, the seventh modification is an example in which the wireless roadside device 100 estimates the RSSI in consideration of the manufacturer type of the on-vehicle communication device 250. Specifically, first, the message processing unit 130 acquires the MAC address from the wireless signal. Second, the RSSI estimating unit 140 acquires the manufacturer type of the in-vehicle communication device 250 mounted on the vehicle 200 from the MAC address, and estimates the RSSI (first RSSI) based on the distance and the manufacturer type.

Thereby, for example, even if the wireless roadside device 100 exhibits different behavior depending on the manufacturer that manufactured the in-vehicle communication device 250, it is possible to estimate the RSSI for each manufacturer. Therefore, in the wireless roadside device 100, by determining the abnormality of the antenna 110 using the estimated RSSI, it is possible to appropriately determine the abnormality of the antenna even if the in-vehicle communication device 250 is made by a different manufacturer.

FIG. 12 is a diagram illustrating an example of an internal estimation table. The example in FIG. 12 shows an example of estimated RSSI by two manufacturers, "Company A" and "Company B" as manufacturer types. However, in the example of FIG. 12, when the distance between the vehicle 200 and the wireless roadside machine 100 is the same, the estimated RSSI of "Company A" and the estimated RSSI of "Company B" represent an example of the same numerical value. . As described above, when the distances are the same, the estimated RSSI of "Company A" and the estimated RSSI of "Company B" may be different values.

As mentioned above, the vehicle information message includes the MAC address. The MAC address includes the manufacturer code (or manufacturer type) of the manufacturer that manufactured the in-vehicle communication device 250. Therefore, the message processing unit 130 can acquire the manufacturer code from the vehicle information message (or wireless signal). The RSSI estimation unit 140 estimates the RSSI using the distance calculated from the position information and the manufacturer code. For example, the RSSI estimation unit 140 can obtain different estimated RSSIs for each manufacturer by correcting the estimated RSSIs calculated from the location information using a predetermined calculation formula.

(Eighth modification example according to the first embodiment)
Next, an eighth modification example of the first embodiment will be described. The eighth modification will also be explained mainly focusing on the differences from the first embodiment.

As described in the first embodiment, the abnormality detection unit 160 determines whether the antenna 110 is abnormal based on whether the difference between the measured RSSI and the estimated RSSI is greater than or equal to the first threshold. Here, a case is assumed in which an obstacle exists in a certain specific direction in the wireless roadside machine 100. In this case, in the wireless roadside device 100, the RSSI of the radio signal received from the specific direction may be lower than the RSSI of the radio signal received from other directions due to the presence of the obstacle.

Therefore, in the eighth modification, in the wireless roadside machine 100, as a result of the measured RSSI being lower in a certain specific direction compared to others, the difference between the measured RSSI and the estimated RSSI in the specific direction is less than the first threshold. However, the antenna should not be determined to be abnormal.

Specifically, first, the RSSI estimation unit 140 calculates the orientation of the vehicle 200 with respect to the wireless roadside machine 100 based on the position information. Second, the abnormality detection unit 160 does not determine that the antenna 110 is abnormal even if the measured RSSI (second RSSI) in a specific direction becomes lower than the measured RSSI (second RSSI) in another direction at the same distance.

As a result, for example, in the wireless roadside device 100, even if the measured RSSI becomes lower than in other directions due to the presence of an obstacle in a specific direction, it will not be determined that the antenna 110 is abnormal. It becomes possible to make a judgment.

In this case, the abnormality detection unit 160 compares the measured RSSI in all directions and the estimated RSSI at the same distance as the measured RSSI, and determines that the number of times the difference is greater than or equal to the first threshold is (consecutive) a second threshold. If it exceeds , it may be determined that the antenna is abnormal.

FIG. 13(A) shows an example of location information, and FIG. 13(B) shows an example of estimated RSSI. As shown in FIG. 13A, the measured RSSI in the direction of latitude "34.999" is generally lower than the measured RSSI in the direction of latitude "35.001". Therefore, as shown in FIG. 13(B), the abnormality detection unit 160 detects that the difference between each measured RSSI and each estimated RSSI in the direction of latitude "34.999" is equal to or greater than the first threshold. It has been judged as "NG". In this case, the abnormality detection unit 160 determines that the number of times the difference between each measured RSSI and each estimated RSSI is equal to or greater than the first threshold in all directions including latitude "35.001" is equal to or greater than the second threshold (consecutive). If detected, it may be determined that the antenna 110 is abnormal.

[Other embodiments]
In the embodiment described above, an example in which the wireless lineside machine 100 detects an antenna abnormality has been described. For example, the server device 300 may detect an antenna abnormality. In this case, for example, the wireless roadside device 100 includes a wireless reception section 120, a message processing section 130, an RSSI estimation section 140, and an RSSI calculation section 150, and the server device 300 includes an abnormality detection section 160 and an abnormality notification section. 170. Specifically, the RSSI estimation unit 140 transmits the estimated RSSI to the server device 300, the RSSI calculation unit 150 also transmits the measured RSSI to the server device 300, and the abnormality detection unit 160 of the server device 300 determines the abnormality. Good too. This is an example of abnormality detection using the so-called cloud method by the server device 300. Thereby, for example, in the server device 300, it is possible to centrally manage antenna abnormalities of the wireless lineside devices 100 under its control.

A program that causes a computer to execute each process according to the embodiments described above may be provided. The program may be recorded on a computer readable medium. Computer-readable media allow programs to be installed on a computer. Here, the computer-readable medium on which the program is recorded may be a non-transitory recording medium. The non-transitory recording medium is not particularly limited, and may be, for example, a recording medium such as a CD-ROM or a DVD-ROM. Such a recording medium may be included in the abnormality detection section 160. The abnormality detection unit 160 may implement each of the functions described in the above-described embodiments by reading a program from a recording medium and executing it. Therefore, the abnormality detection section 160 may be configured with a processor or a controller such as a CPU (Central Processing Unit) or a DSP (Digital Signal Processor).

Although the embodiments have been described above in detail with reference to the drawings, the specific configuration is not limited to that described above, and various design changes can be made without departing from the scope of the invention. Furthermore, it is also possible to combine each embodiment, each operation example, or each process within a range that does not contradict each other.

(Additional note)
In one embodiment, (1) a wireless roadside device that performs road-to-vehicle communication with a vehicle via an antenna, including a wireless receiving unit that receives a wireless signal transmitted from the vehicle, and a position of the vehicle based on the wireless signal; a message processing unit that acquires information; an RSSI estimating unit that calculates a distance between the wireless roadside machine and the vehicle based on the position information, and estimates a first RSSI of the wireless signal based on the distance; The antenna includes an RSSI calculation unit that measures a second RSSI of the wireless signal, and an abnormality detection unit that detects an abnormality in the antenna based on the first RSSI and the second RSSI.

(2) The wireless roadside machine according to (1) above further comprises, in the abnormality detection unit, correcting the first RSSI when the difference between the first RSSI and the second RSSI is equal to or greater than a threshold value within the correction period; The method may include detecting an abnormality in the antenna based on the corrected first RSSI and the second RSSI after a period of time has elapsed.

(3) The wireless roadside machine of (1) or (2) above further calculates, in the RSSI estimating section, the direction of the vehicle with respect to the wireless roadside machine based on the position information, and calculates the distance and the direction. The method may include estimating the first RSSI based on.

(4) The wireless roadside machine according to any one of (1) to (3) above further includes, in the RSSI estimating section, an indication between the wireless roadside machine and the positional information based on the positional information acquired from the map information. calculate the distance to the location where the information is located, estimate the first RSSI based on the distance, generate an internal estimation table showing a correspondence relationship between the location information and the first RSSI, and use the internal estimation table to , obtaining the first RSSI corresponding to the location information obtained by the message processing unit.

(5) The wireless roadside machine according to any one of (1) to (4) above further acquires the speed of the vehicle from the radio signal in the message processing unit, and acquires the speed of the vehicle from the radio signal in the RSSI estimation unit. The method may include not correcting the first RSSI when the speed is equal to or higher than a predetermined speed.

(6) The wireless roadside machine according to any one of (1) to (5) above further acquires the direction of the vehicle from the radio signal in the message processing unit, and acquires the direction of the vehicle from the radio signal in the RSSI estimation unit. The method may include calculating a traveling direction of the vehicle with respect to the wireless roadside machine from the azimuth, and estimating the first RSSI based on the distance and the traveling direction.

(7) The wireless roadside machine according to any one of (1) to (6) above further acquires the vehicle type from the radio signal in the message processing unit, and acquires the distance and the vehicle type in the RSSI estimation unit. The method may include estimating the first RSSI based on the type.

(8) The wireless roadside machine according to any one of (1) to (7) above further acquires a MAC address from the radio signal in the message processing unit, and acquires a MAC address from the MAC address in the RSSI estimating unit. The method may include obtaining a manufacturer type of an in-vehicle communication device installed in the vehicle, and estimating the first RSSI based on the distance and the manufacturer type.

(9) The wireless roadside machine according to any one of (1) to (8) above calculates the orientation of the vehicle with respect to the wireless roadside machine based on the position information in the RSSI estimating unit, and The method may include not determining that the antenna is abnormal even if the second RSSI in a specific direction becomes lower than the second RSSI in another direction at the same distance.

In one embodiment, (10) a traffic communication system includes the wireless roadside machine according to any one of (1) to (9) above.

In one embodiment, (11) a traffic communication method performed by a wireless roadside device that performs wireless communication with a vehicle via an antenna, the method comprising: receiving a wireless signal transmitted from the vehicle; a step of acquiring position information of a vehicle; a step of calculating a distance between the wireless roadside machine and the vehicle based on the position information; and a step of estimating a first RSSI of the wireless signal based on the distance; The method includes the steps of measuring a second RSSI of a wireless signal, and detecting an abnormality in the antenna based on the first RSSI and the second RSSI.

10: Traffic communication system 100: Wireless roadside device 110: Antenna 120: Radio receiving section 120: Radio receiving section 130: Message processing section 140: RSSI estimation section 150: RSSI calculation section 160: Abnormality detection section 170: Abnormality notification section 200: Vehicle 210: GNSS receiving section 220: Message generating section 230: Wireless transmitting section 240: Antenna 250: In-vehicle communication device
300: Server device

Claims (11)

A wireless roadside machine that performs road-to-vehicle communication with a vehicle via an antenna,
a wireless receiving unit that receives a wireless signal transmitted from the vehicle;
a message processing unit that acquires position information of the vehicle from the wireless signal;
an RSSI estimation unit that calculates a distance between the wireless roadside machine and the vehicle based on the position information, and estimates a first RSSI of the wireless signal based on the distance;
an RSSI calculation unit that measures a second RSSI of the wireless signal;
A wireless lineside machine, comprising: an abnormality detection unit that detects an abnormality in the antenna based on the first RSSI and the second RSSI. The abnormality detection unit corrects the first RSSI when a difference between the first RSSI and the second RSSI is equal to or greater than a threshold within a correction period, and corrects the corrected first RSSI and the second RSSI after the correction period has elapsed. detecting an abnormality in the antenna based on
The wireless roadside machine according to claim 1. The RSSI estimation unit calculates a direction of the vehicle with respect to the wireless roadside machine based on the position information, and estimates the first RSSI based on the distance and the direction.
The wireless roadside machine according to claim 1. The RSSI estimation unit calculates the distance between the wireless trackside machine and the position indicated by the position information based on the position information acquired from map information, and estimates the first RSSI based on the distance. , generates an internal estimation table indicating a correspondence relationship between the location information and the first RSSI, and uses the internal estimation table to obtain the first RSSI corresponding to the location information obtained by the message processing unit. The wireless roadside machine described in 1. The message processing unit obtains the speed of the vehicle from the wireless signal,
The RSSI estimation unit does not correct the first RSSI when the speed of the vehicle is equal to or higher than a predetermined speed.
The wireless roadside machine according to claim 2. The message processing unit obtains the direction of the vehicle from the wireless signal,
The wireless roadside machine according to claim 1, wherein the RSSI estimation unit calculates the traveling direction of the vehicle with respect to the wireless roadside machine from the azimuth of the vehicle, and estimates the first RSSI based on the distance and the traveling direction. . The message processing unit acquires the type of the vehicle from the wireless signal,
The wireless roadside machine according to claim 1, wherein the RSSI estimation unit estimates the first RSSI based on the distance and the type. The message processing unit obtains a MAC address from the wireless signal,
The wireless roadside device according to claim 1, wherein the RSSI estimation unit acquires a manufacturer type of an on-vehicle communication device mounted on the vehicle from the MAC address, and estimates the first RSSI based on the distance and the manufacturer type. . The RSSI estimating unit calculates the orientation of the vehicle with respect to the wireless roadside machine based on the position information, and the abnormality detecting unit is configured such that the second RSSI in a specific direction is higher than the second RSSI in another direction at the same distance. The wireless roadside device according to claim 1, wherein even if the antenna becomes low, it is not determined that the antenna is abnormal. A traffic communication system comprising the wireless roadside machine according to any one of claims 1 to 9. A traffic communication method performed by a wireless roadside machine that performs wireless communication with a vehicle via an antenna,
receiving a wireless signal transmitted from the vehicle;
obtaining location information of the vehicle from the wireless signal;
calculating a distance between the wireless roadside machine and the vehicle based on the position information, and estimating a first RSSI of the wireless signal based on the distance;
measuring a second RSSI of the wireless signal;
A transportation communication method, comprising: detecting an abnormality in the antenna based on the first RSSI and the second RSSI.

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