JP7764447B2 - Radio base station, mobile station, vehicle, and message transmission method - Google Patents

Description

The present invention relates to a radio base station, a mobile station, a vehicle, and a message transmission method.

In advanced transportation systems (e.g., ITS: Intelligent Transport System), technology has been proposed for wireless communication between roadside units, which are base stations installed around roads, and in-vehicle units, which are mobile stations installed in vehicles (see, for example, Non-Patent Document 1).

Association of Radio Industries and Businesses, "700 MHz Band Intelligent Transport Systems ARIB-STD T109 Version 1.3," [online], July 27, 2017, [searched June 22, 2018], Internet http://www.arib.or.jp/tyosakenkyuu/kikaku_tushin/tsuushin_kikaku_number.html

Conventional ITS systems aim to reduce traffic accidents by targeting vehicles such as automobiles traveling on roads, and do not fully consider railway vehicles traveling on railroads.

For this reason, conventional ITS has room for improvement in reducing level crossing accidents at crossings where railways and roads intersect, particularly those caused by vehicles being held up at the crossing as a result of misjudging congestion ahead of the crossing (so-called congestion ahead).

Therefore, the present invention aims to provide a base station, mobile station, vehicle, and message transmission method that can reduce railroad crossing accidents.

A base station according to a first aspect is installed near a railroad crossing where a railroad and a road intersect. The base station includes a transmitter that transmits a message via wireless communication to vehicles traveling on the road toward the entrance side of the railroad crossing. The transmitter transmits the message to the vehicles, the message including at least one information element indicating the traffic conditions on the road at the exit side of the railroad crossing.

A mobile station according to a second aspect is installed in a vehicle. The mobile station has a receiving unit that receives a message via wireless communication from a base station installed in the vicinity of a railroad crossing where a railroad and a road intersect when the vehicle travels along the road toward the entrance side of the railroad crossing. The receiving unit receives the message from the base station, which includes at least one information element indicating the traffic conditions on the road at the exit side of the railroad crossing.

A vehicle according to the third aspect is equipped with a mobile station according to the second aspect.

A fourth aspect of the message transmission method is a method in which a base station located near a railroad crossing where a railroad and a road intersect transmits a message to vehicles via wireless communication, and includes a step of transmitting a message containing information elements indicating the traffic conditions on the road at the exit side of the railroad crossing to vehicles traveling on the road toward the entrance side of the railroad crossing.

One aspect of the present invention provides a base station, a mobile station, a vehicle, and a message transmission method that can reduce railroad crossing accidents.

FIG. 1 is a diagram showing a configuration of a transportation communication system according to an embodiment. FIG. 2 is a diagram illustrating the configuration of a roadside device according to an embodiment. 3A to 3C are diagrams showing the structure of a message for a vehicle according to one embodiment. FIG. 4 is a diagram showing the configuration of a vehicle according to one embodiment. FIG. 5 is a diagram illustrating an example of an operation sequence of the transportation communication system according to an embodiment.

The embodiments will be described with reference to the drawings. Note that in the following description of the drawings, identical or similar parts are designated by the same or similar reference numerals.

(Transportation and Communication Systems)
First, a transport communication system according to an embodiment will be described. Fig. 1 is a diagram showing the configuration of the transport communication system according to an embodiment.

As shown in FIG. 1, a transportation communication system according to one embodiment includes vehicles 10a to 10d and roadside units 20a and 20b. Hereinafter, when vehicles 10a to 10d are not distinguished from one another, they will simply be referred to as vehicle 10, and when roadside units 20a and 20b are not distinguished from one another, they will simply be referred to as roadside unit 20. Roadside unit 20 is an example of a base station.

Vehicle 10 travels on road 110. In Figure 1, a four-wheeled motor vehicle is shown as an example of vehicle 10, but vehicle 10 may also be a motorcycle, a three-wheeled motor vehicle, an electric bicycle, or the like. Also, while a one-lane road 110 is shown as an example, road 110 may have multiple lanes.

The roadside unit 20a is installed near a railroad crossing 150 where a road 110 and a railway 120 intersect. Railway vehicles (not shown) travel on the railway 120. While Figure 1 illustrates a railway 120 consisting of a single track, the railway 120 may have multiple tracks.

Level crossing 150 is equipped with level crossing safety equipment. Figure 1 shows an example of level crossing safety equipment, including level crossing warning devices 130 (130a and 130b) and level crossing barriers 140 (140a and 140b). Level crossing warning devices 130 are devices that notify vehicle drivers traveling on road 110 of the presence of level crossing 150 and, if a railroad vehicle approaches, issue a sound and light warning to stop road traffic. Level crossing barrier 140 is a device that restricts traffic on road 110 to give priority to railroad vehicles. Level crossing barrier 140 has a barrier and a mechanism for raising and lowering it.

A sensor 160 is installed around the railroad crossing 150. The sensor 160 detects the traffic conditions on the road 110 on the exit side of the railroad crossing 150 and outputs the detection results to the roadside device 20a. The sensor 160 may be any sensor capable of detecting traffic conditions, such as an ultrasonic sensor, optical sensor, or image sensor. Note that the exit side of the railroad crossing 150 refers to the rear side of the railroad crossing 150 in the direction of vehicle traffic on the lane, and the entrance side of the railroad crossing 150 refers to the front side of the railroad crossing 150 in the direction of vehicle traffic on the lane.

A traffic signal 170 is installed on the road 110 at the exit side of the railroad crossing 150, at a distance from the railroad crossing 150. The traffic signal 170 is a device that displays signals such as permission to proceed and stop instructions to ensure traffic safety on the road 110 and to smooth traffic flow. Figure 1 shows an example in which the traffic signal 170 is displaying a light color indicating a stop instruction, causing vehicles 10b to 10d to stop.

Roadside unit 20b is installed near traffic signal 170. Roadside unit 20b acquires signal light color information indicating the signal light color of traffic signal 170. The signal light color information may include not only information indicating the current signal light color, but also information indicating the signal light color transition pattern over a certain period of time in the future. Roadside unit 20b transmits the signal light color information to roadside unit 20a via wireless communication.

The roadside unit 20a transmits a message via wireless communication to a vehicle 10a traveling on the road 110 toward the entrance side of the railroad crossing 150. Specifically, the roadside unit 20a transmits a message to the vehicle 10a that includes at least one information element indicating the traffic conditions on the road 110 at the exit side of the railroad crossing 150. For example, the at least one information element indicating the traffic conditions on the road 110 at the exit side of the railroad crossing 150 is based on signal light color information that the roadside unit 20a receives from the roadside unit 20b and detection information that the roadside unit 20a acquires from the sensor 160.

Vehicle 10a receives a message from roadside unit 20a. Based on the message received from roadside unit 20a, vehicle 10a presents the driver of vehicle 10a with information about the traffic conditions on road 110 at the exit side of railroad crossing 150. If vehicle 10a is an autonomous vehicle, vehicle 10a may automatically control the progression or stopping of vehicle 10a toward railroad crossing 150, taking into account the traffic conditions on road 110 at the exit side of railroad crossing 150, based on the message received from roadside unit 20a.

In this way, by sending a message including at least one information element indicating the traffic conditions on the road 110 at the exit side of the railroad crossing 150 to a vehicle 10a traveling on the road 110 toward the entrance side of the railroad crossing 150, it is possible to reduce railroad crossing accidents at the railroad crossing 150. In particular, it is possible to reduce railroad crossing accidents that occur when the driver of vehicle 10a misjudges the congestion ahead of the crossing (so-called congestion ahead), causing vehicle 10a to become stuck at the railroad crossing 150.

(roadside unit)
Next, a roadside device 20a according to an embodiment will be described. Fig. 2 is a diagram showing the configuration of the roadside device 20a according to an embodiment.

As shown in FIG. 2, the roadside unit 20a has an antenna 21a, a wireless communication unit 21, a control unit 22, and an interface 23. The interface 23 is an interface for communicating with the sensor 160. The roadside unit 20a may further have an interface for communicating with the railroad crossing warning device 130 and the railroad crossing barrier 140. The roadside unit 20a may further have an interface for communicating with a sensor for detecting the approach of a railroad vehicle. The roadside unit 20a may also have a GNSS (Global Navigation Satellite System) receiver.

The wireless communication unit 21 performs wireless communication via the antenna 21a. The antenna 21a may be an omnidirectional antenna or a directional antenna that has directivity toward the entrance side of the railroad crossing 150. The antenna 21a may also be an adaptive array antenna whose directivity can be dynamically changed.

The wireless communication method of the wireless communication unit 21 may be a method compliant with ARIB T109, a method compliant with the 3GPP (registered trademark; the same applies below) V2X (Vehicle to Everything) standard, or a method compliant with a wireless LAN standard such as the IEEE 802.11 series. The wireless communication unit 21 may be configured to be compatible with all of these communication standards.

The wireless communication unit 21 has a receiving unit 21b that converts wireless signals received by the antenna 21a into baseband signals (received packets) and outputs them to the control unit 22. The wireless communication unit 21 also has a transmitting unit 21c that converts baseband signals (transmitted packets) output by the control unit 22 into wireless signals and transmits them from the antenna 21a.

If the wireless communication unit 21 complies with the ARIB T109 standard, it may have a function to perform carrier sensing using the receiver 21b to determine whether a radio wave frequency (e.g., the 700 MHz band) is available. The transmitter 21c of the wireless communication unit 21 may transmit packets at a timing determined based on the results of the carrier sensing. One or more packets may constitute one message.

For example, the wireless communication unit 21 performs road-to-road communication with another roadside unit 20b. The road-to-road communication may be performed by unicast, broadcast, or multicast. The receiving unit 21b of the wireless communication unit 21 receives road-to-road communication packets from the roadside unit 20b. The road-to-road communication packets may include identification information used to identify the sender. The receiving unit 21b receives a message consisting of one or more packets from the roadside unit 20b. The message includes the signal light color information described above.

The wireless communication unit 21 performs road-to-vehicle communication with the vehicle 10. Road-to-vehicle communication may be performed by unicast, broadcast, or multicast. Road-to-vehicle communication packets transmitted to the vehicle 10 may include identification information used to identify the sender, synchronization information indicating the synchronization method for the roadside unit 20a, the transmission time of the packet, and period information indicating the period of road-to-vehicle communication (e.g., the number of road-to-vehicle communication transfers, the period length of road-to-vehicle communication), etc.

The transmitter 21c of the wireless communication unit 21 transmits a message consisting of one or more packets to the vehicle 10 via road-to-vehicle communication. This message is generated by the control unit 22.

The control unit 22 is composed of a control circuit having at least one memory and at least one processor electrically connected to the memory. The control unit 22 controls various functions of the roadside unit 20a. The control unit 22 periodically generates messages for the vehicle 10 and periodically transmits the messages via the transmission unit 21c.

Figure 3 is a diagram showing the structure of a message M for a vehicle 10 according to one embodiment. Message M may be a message transmitted and received at layer 2 or layer 3 of the OSI reference model, or may be a message transmitted and received at the application layer.

As shown in Figure 3(A), message M has information elements E1 to E5.

Information element E1 is railroad crossing presence information indicating that a railroad crossing 150 exists on road 110. Information element E1 may be a flag that is set to "1" if a railroad crossing 150 exists and to "0" if a railroad crossing 150 does not exist.

Information element E2 is railroad crossing geographic information that indicates the geographic attributes of railroad crossing 150. Information element E2 includes information indicating the geographic location (latitude and longitude) of railroad crossing 150. Information element E2 may also include information indicating the size of railroad crossing 150, for example, the distance between the entrance and exit. The information indicating the distance between the entrance and exit of railroad crossing 150 may be a numerical value indicating this distance (for example, how many meters), or may be information indicating whether railway 120 is single-track or double-track.

Information element E3 is railway vehicle approach information that indicates whether or not an approaching railway vehicle to the railway crossing 150 has been detected. Information element E3 may be a flag that is set to "1" if an approaching railway vehicle has been detected, and to "0" if an approaching railway vehicle has not been detected. Information element E3 may indicate whether or not the railway crossing warning device 130 is performing an alarm operation, or whether or not the railway crossing barrier 140 is performing a barrier operation.

Information element E4 is at least one information element (crossing destination traffic information) that indicates the traffic conditions on road 110 at the exit side of railroad crossing 150. Figure 3(B) shows configuration example 1 of information element E4. Figure 3(C) shows configuration example 2 of information element E4.

As shown in FIG. 3(B), information element E4 includes information element E41 (leading vehicle position information) indicating the latitude and longitude of leading vehicle 10b located on road 110 on the exit side of railroad crossing 150, and information element E42 (leading vehicle speed information) indicating the travel speed of leading vehicle 10b. Leading vehicle 10b refers to the vehicle 10 closest to railroad crossing 150 on the exit side of railroad crossing 150, i.e., the vehicle 10 that most recently passed through railroad crossing 150.

Information element E41 may be information indicating whether or not a leading vehicle 10b is present at the exit side of the railroad crossing 150. Information element E42 may be a numerical value indicating the traveling speed of leading vehicle 10b (e.g., kilometers per hour), or a flag indicating whether leading vehicle 10b is stopped. A stopped state refers to a state in which the traveling speed is below a threshold, for example, a state in which the traveling speed is zero.

As shown in FIG. 3(C), information element E4 includes information element E44 (preceding vehicle stop information) that indicates whether there is a stopped preceding vehicle 10b on the road 110 on the exit side of the railroad crossing 150. Information element E44 may be a flag that is set to "1" if there is a stopped preceding vehicle 10b on the road 110 on the exit side of the railroad crossing 150, and to "0" if there is not.

The control unit 22 may generate information elements E41, E42, and E44 based on the detection results obtained by the sensor 160. Alternatively, the control unit 22 may generate information elements E41, E42, and E44 based on a message received by the receiving unit 21b from the leading vehicle 10b via road-to-vehicle communication. This message includes location information indicating the geographical position of the leading vehicle 10b and speed information indicating the traveling speed of the leading vehicle 10b.

If a traffic signal 170 is installed on the road 110 at the exit side of the railroad crossing 150 at a distance from the railroad crossing 150, information element E4 includes information element E43 (railroad crossing signal information) that indicates the signal light color of the traffic signal 170. Information element E43 may include not only information indicating the current signal light color, but also information indicating the signal light color transition pattern over a certain period of time in the future.

The control unit 22 may generate information element E43 based on signal light color information received by the receiving unit 21b from another roadside unit 20b via road-to-road communication. Alternatively, the control unit 22 may generate information element E43 based on signal light color information obtained via a communication line from a traffic management center (not shown).

If road 110 has multiple lanes for round-trip traffic, message M may include information element E5 (target lane information) for identifying the lane targeted by information element E4. Information element E5 may be an identifier for the lane targeted by information element E4, or may be information indicating the direction (bearing) of vehicle traffic in the lane targeted by information element E4.

(vehicle)
Next, a vehicle 10a according to an embodiment will be described. Fig. 4 is a diagram showing the configuration of the vehicle 10a according to an embodiment.

As shown in FIG. 4, the vehicle 10a has a GNSS receiver 12, a presentation unit 13, a drive control unit 14, and an onboard device 16. The onboard device 16 is an example of a mobile station provided in the vehicle 10a. The onboard device 16 has an antenna 11a, a wireless communication unit 11, and a control unit 15.

The wireless communication unit 11 performs wireless communication via the antenna 11a. The antenna 11a may be an omnidirectional antenna or a directional antenna.

The wireless communication method of the wireless communication unit 11 may be a method compliant with ARIB T109, a method compliant with the 3GPP V2X standard, or a method compliant with a wireless LAN standard such as the IEEE 802.11 series. The wireless communication unit 11 may be configured to be compatible with all of these communication standards.

The wireless communication unit 11 has a receiving unit 11b that converts wireless signals received by the antenna 11a into baseband signals (received packets) and outputs them to the control unit 15. The wireless communication unit 11 also has a transmitting unit 11c that converts baseband signals (transmitted packets) output by the control unit 15 into wireless signals and transmits them from the antenna 11a.

When the wireless communication unit 11 complies with the ARIB T109 standard, it may have the function of performing carrier sensing using the receiver 11b to determine whether a radio wave frequency (e.g., the 700 MHz band) is available. The transmitter 11c of the wireless communication unit 11 may transmit packets at a timing determined based on the results of the carrier sensing. One or more packets may constitute one message.

The wireless communication unit 11 performs road-to-vehicle communication with the roadside unit 20a. The road-to-vehicle communication may be performed by unicast or broadcast. The receiving unit 11b of the wireless communication unit 11 receives a message M from the roadside unit 20a.

The GNSS receiver 12 performs positioning based on GNSS satellite signals and outputs position information indicating the current geographical position (latitude and longitude) of the vehicle 10a to the control unit 15.

Under the control of the control unit 15, the presentation unit 13 presents information to the driver of the vehicle 10a. For example, the presentation unit 13 includes at least one of a display that displays information and a speaker that outputs information audibly. Hereinafter, presentation of information refers to at least one of displaying information and outputting information audibly.

The drive control unit 14 controls the engine or motor as a power source, the power transmission mechanism, the brakes, etc. If the vehicle 10a is an autonomous vehicle, the drive control unit 14 may control the drive of the vehicle 10a in cooperation with the control unit 15.

The control unit 15 is composed of a control circuit having at least one memory and at least one processor electrically connected to the memory. The control unit 15 controls various functions in the vehicle 10a (on-board device 16).

For example, the control unit 15 controls the presentation unit 13 based on a message M received by the receiving unit 11b from the roadside unit 20a.

The control unit 15 may control the presentation unit 13 to present information that a railroad crossing 150 is located in the direction of travel of the vehicle 10a, based on information element E1 (railroad crossing presence information) included in the message M.

The control unit 15 may control the presentation unit 13 to present information indicating the geographic attributes of the railroad crossing 150 based on information element E2 (railroad crossing geographic information) included in the message M. Here, the control unit 15 may control the presentation unit 13 to present information indicating the distance between the current position of the vehicle 10a and the position of the railroad crossing 150.

The control unit 15 may control the presentation unit 13 to present information indicating whether or not a railway vehicle approaching the railroad crossing 150 has been detected, based on information element E3 (railroad vehicle approach information) included in the message M.

The control unit 15 may control the presentation unit 13 to present information indicating the traffic conditions on the road 110 at the exit side of the railroad crossing 150 based on information element E4 (traffic information ahead of the railroad crossing) included in the message M.

For example, if the control unit 15 determines, based on information element E41 (leading vehicle position information), information element E42 (leading vehicle speed information), or information element E44 (leading vehicle stop information), that there is a stopped leading vehicle 10b on the road 110 on the exit side of the railroad crossing 150, it controls the presentation unit 13 to present information to that effect. Here, the control unit 15 may alert the driver by presenting information such as "Caution: Entering the railroad crossing" or "Congestion ahead of the railroad crossing. Caution: Entering."

When the control unit 15 determines, based on information element E43 (railroad crossing signal information), that the traffic signal 170 at the exit side of the railroad crossing 150 is displaying a signal indicating a stop, it controls the presentation unit 13 to present information to that effect. Here, the control unit 15 may alert the driver by presenting information such as "Red light ahead of railroad crossing. Be careful entering."

If road 110 has multiple lanes for round-trip traffic, control unit 15 may determine whether to present information based on information element E4 based on information element E5 (target lane information) included in message M. Specifically, control unit 15 presents information based on information element E4 only if the lane in which vehicle 10a is traveling matches the lane indicated by information element E5.

If the vehicle 10a is an autonomous vehicle, the control unit 15 may control the driving of the vehicle 10a based on the message M received by the receiving unit 11b from the roadside unit 20a.

The control unit 15 may control the vehicle 10a to decelerate as the vehicle 10a approaches the railroad crossing 150 and to stop temporarily before the railroad crossing 150 based on information element E1 (railroad crossing presence information) and information element E2 (railroad crossing geographic information) contained in the message M.

Furthermore, if the control unit 15 determines that a railway vehicle is approaching the railroad crossing 150 based on information element E3 (railroad vehicle approach information) included in message M, the control unit 15 may control the vehicle 10a to continue to be stopped until the railway vehicle passes the railroad crossing 150.

The control unit 15 may control the entry of the vehicle 10a into the railroad crossing 150, taking into account the traffic conditions on the road 110 on the exit side of the railroad crossing 150, based on information element E4 (traffic information ahead of the railroad crossing) included in the message M.

For example, if the control unit 15 determines, based on information element E41 (leading vehicle position information), information element E42 (leading vehicle speed information), or information element E44 (leading vehicle stop information), that there is a leading vehicle 10b that is stopped on the road 110 on the exit side of the railroad crossing 150, the control unit 15 may control the vehicle 10a to continue to be stopped until the leading vehicle 10b resumes movement or moves a predetermined distance away from the railroad crossing 150.

If the control unit 15 determines, based on information element E43 (railroad crossing destination signal information), that the traffic signal 170 at the exit side of the railroad crossing 150 is displaying a signal indicating a stop, it may control the vehicle 10a to continue in a stopped state until the traffic signal 170 switches to a signal indicating permission to proceed.

If road 110 has multiple lanes for round-trip traffic, control unit 15 may determine whether to present information based on information element E4 based on information element E5 (target lane information) included in message M. Specifically, control unit 15 performs drive control of vehicle 10a based on information element E4 only if the lane in which vehicle 10a is traveling matches the lane indicated by information element E5.

(Example of operation sequence)
5 is a diagram illustrating an example of an operation sequence of a transportation communication system according to an embodiment. The sequence illustrated in FIG. 5 may be executed periodically.

As shown in FIG. 5, in step S1, the receiver 21b of the roadside unit 20a receives signal light color information from the roadside unit 20b via road-to-road communication.

In step S2, the control unit 22 of the roadside unit 20a acquires detection information from the sensor 160 via the interface 23. Note that the order of steps S1 and S2 may be reversed.

In step S3, the control unit 22 of the roadside unit 20a generates a message M.

In step S4, the transmitter 21c of the roadside device 20a transmits the generated message M to the vehicle 10a via road-to-vehicle communication. The receiver 11b of the vehicle 10a receives the message M from the roadside device 20a.

In step S5, the control unit 15 of the vehicle 10a presents information or controls the driving of the vehicle 10a based on the received message M.

(Other embodiments)
In the above-described embodiment, an example was described in which information element E4 (traffic information at the crossing destination) indicating the traffic conditions on road 110 at the exit side of railroad crossing 150 individually includes information elements regarding preceding vehicle 10b and traffic light 170.

Here, the information element regarding the preceding vehicle 10b indicates the current stopped state of the preceding vehicle 10b at the exit side of the railroad crossing 150, and the information element regarding the traffic light 170 can be thought of as indicating the near-future congestion situation at the exit side of the railroad crossing 150.

However, the roadside unit 20a may take into consideration the conditions of both the preceding vehicle 10b and the traffic signal 170 to determine whether or not to permit the vehicle 10a to enter the railroad crossing 150, and transmit a single information element indicating whether or not the vehicle 10a is permitted to enter the railroad crossing 150 to the vehicle 10a as information element E4 (railroad crossing destination traffic information).

For example, if the roadside device 20a determines that the preceding vehicle 10b is stopped at the exit side of the railroad crossing 150 or that congestion will occur on the exit side of the railroad crossing 150 in the near future, it transmits information element E4 (traffic information ahead of the railroad crossing) indicating that entry into the railroad crossing 150 is prohibited to the vehicle 10a.

A program may be provided that causes a computer to execute each process performed by the vehicle 10 (onboard device 16) and a program that causes a computer to execute each process performed by the roadside device 20. The program may be recorded on a computer-readable medium. Using the computer-readable medium, the program can 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 CD-ROM, DVD-ROM, or other recording medium.

The circuits that execute the processes performed by the vehicle 10 (on-board device 16) may be integrated, and at least a portion of the vehicle 10 (on-board device 16) may be configured as a semiconductor integrated circuit (chip set, SoC). Furthermore, the circuits that execute the processes performed by the roadside device 20 may be integrated, and the roadside device 20 may be configured as a semiconductor integrated circuit (chip set, SoC).

One embodiment has been described in detail above with reference to the drawings, but the specific configuration is not limited to that described above, and various design changes can be made without departing from the spirit of the invention.

10: Vehicle 11: Wireless communication unit 11a: Antenna 11b: Receiving unit 11c: Transmitting unit 12: GNSS receiver 13: Presentation unit 14: Drive control unit 15: Control unit 16: In-vehicle device 20: Roadside device 21: Wireless communication unit 21a: Antenna 21b: Receiving unit 21c: Transmitting unit 22: Control unit 23: Interface 110: Road 120: Railway 130: Railroad crossing warning device 140: Railroad crossing barrier 150: Railroad crossing road 160: Sensor 170: Traffic signal

Claims (6)

A radio base station installed near a railroad crossing where a railroad and a road intersect,
a transmitter that transmits a message by wireless communication to vehicles traveling on the road toward the entrance side of the railroad crossing,
When a roadside sensor detects a preceding vehicle on the exit side of the railroad crossing, the transmitter transmits the message to the vehicle, including one bit of information indicating whether the preceding vehicle in a stopped state is present on the exit side, so that the vehicle does not become stranded at the railroad crossing. The radio base station according to claim 1 , wherein, when the leading vehicle is present, the transmitter transmits the message to the vehicle, the message including location information indicating the latitude and longitude of the leading vehicle. The radio base station according to claim 2 , wherein the transmitter transmits the message to the vehicle further including direction information indicating a traveling direction of the leading vehicle. A mobile station provided in a vehicle,
a receiving unit that receives a message by wireless communication from a wireless base station provided in the vicinity of a railroad crossing when the vehicle travels along the road toward an entrance side of the railroad crossing where a railroad and a road intersect,
The receiving unit receives the message from the wireless base station, which includes one bit of information indicating whether or not there is a stopped preceding vehicle on the exit side of the railroad crossing detected by a roadside sensor, so that the vehicle does not become stuck at the railroad crossing. A vehicle comprising the mobile station according to claim 4. a wireless communication step in which a wireless base station provided in the vicinity of a level crossing where a railroad and a road intersect transmits a message by wireless communication to vehicles traveling on the road toward an entrance side of the level crossing,
In the wireless communication step, when a roadside sensor detects a stopped preceding vehicle on the exit side of the railroad crossing so that the vehicle does not become stuck at the railroad crossing, the message includes one bit of information indicating whether or not the preceding vehicle is present, and the message notifies the vehicle of whether or not the preceding vehicle is present .