JP6912972B2 - Roadside unit, in-vehicle device, in-vehicle device communication system, in-vehicle device communication method, and computer program - Google Patents

Description

The present invention relates to a roadside unit that wirelessly communicates with an on-board unit mounted on a vehicle, an on-board unit that wirelessly communicates with the roadside unit, an on-board unit communication system that wirelessly communicates between the on-board unit and the roadside unit, an on-board unit communication method, and an on-board unit communication method. The present invention relates to a computer program for causing a roadside unit to communicate with an on-board unit.

Electronic toll collection system (ETC) that allows vehicles to pass non-stop by wirelessly communicating information on toll collection between the roadside unit installed at the tollhouse on the highway and the on-board unit mounted on the vehicle. Collection System) is widespread. In addition, such ETC is also used for entrance / exit management of parking lots. ETC adopts DSRC (Dedicated Short Range Communication), which is a wireless communication method in the 5.8 GHz band, and the roadside machine side forms a narrow wireless communication area on the traveling lane of the vehicle. .. However, even in such a narrow range communication, there is a possibility that the on-board unit mounted on the vehicle in the vicinity of the vehicle to be communicated and the roadside unit communicate erroneously.

Some systems are disclosed in Patent Documents 1 and 2 as a system for preventing such erroneous communication. In the system disclosed in Patent Document 1, a jamming antenna that emits a radio wave having a frequency different from the radio wave radiated in the radio communication area is provided in an adjacent lane adjacent to the lane in which the roadside unit forms the radio communication area. By radiating radio waves from this jamming antenna, a jamming radio wave zone is formed in the adjacent lane, and when a vehicle traveling in the adjacent lane enters the jamming radio wave zone, the in-vehicle device mounted on this vehicle and the roadside unit It is to prevent erroneous communication. Further, in the system disclosed in Patent Document 2, a wireless communication device and a vehicle detection unit are provided at each of the entrance gate and the exit gate adjacent to each other, and a vehicle entering either the entrance gate or the exit gate detects the vehicle. When detected by the unit, each of the two wireless communication devices emits radio waves at the same time to form a radio wave zone at each of the entrance gate and the exit gate, so that the vehicle is mounted on the vehicle that has entered one of the gates. This is to prevent erroneous communication between the on-board unit and the wireless communication device provided at the other gate.

Japanese Unexamined Patent Publication No. 2003-242544 Japanese Patent No. 5239690

However, in the system disclosed in Patent Documents 1 and 2 described above, when the lane in which the antenna is installed and the lane in which the antenna is not installed are mixed, the system is mounted on a vehicle traveling in the lane in which the antenna is not installed. It is conceivable that the on-board unit communicates with the roadside unit, causing erroneous communication. In order to prevent this, it is necessary to install antennas in all lanes to prevent erroneous communication, which makes the system expensive.

The present invention has been made in view of such circumstances, and a main object thereof is to provide a roadside unit, an in-vehicle device, an in-vehicle device communication system, an in-vehicle device communication method, and a computer program capable of solving the above problems. There is.

In order to solve the above-mentioned problems, the roadside unit according to one aspect of the present invention includes an antenna that forms a wireless communication area by radiating radio waves and an on-board unit mounted on a vehicle that has entered the wireless communication area. On the other hand, the wireless communication unit that transmits a request signal requesting identification information for identifying the vehicle-mounted device and receives the identification information from the vehicle-mounted device through the antenna is the same as the wireless communication unit. When the identification information is received a plurality of times, the vehicle-mounted device that has transmitted the identification information is determined as the target of the information communication processing, and the control unit that executes the information communication processing related to the vehicle-mounted device determined as the target. To be equipped with.

In the above aspect, the control unit sets a monitoring period for monitoring the reception of the identification information after the identification information is once received from the vehicle-mounted device by the wireless communication unit, and the identification information is combined with the identification information during the monitoring period. When the identification information is received a plurality of times as a result of receiving the same identification information, the vehicle-mounted device may be determined as the target.

Further, in the above aspect, the control unit may set a non-use period in which the reception of the identification information is not used for determining the target within the monitoring period after the identification information is received by the wireless communication unit. good.

Further, in the above aspect, the monitoring period may be longer than the period obtained by multiplying the impossible period by a number smaller than the plurality of times.

Further, in the above aspect, the impossibility period is a release timer, and the control unit may be set by transmitting the release timer to the vehicle-mounted device by the wireless communication unit.

Further, in the above aspect, when the wireless communication unit receives each of the plurality of identification information transmitted from each of the plurality of vehicle-mounted devices, the control unit gives priority to one identification information over the other identification information. You may monitor it.

Further, in the above aspect, the roadside unit further includes a detection unit for detecting the radio field intensity of the received signal in the wireless communication unit, and the control unit is from each of the plurality of vehicle-mounted devices detected by the detection unit. Based on the radio field strength of the received signal, the one identification information may be monitored with priority over the other identification information.

Further, in the above aspect, after the reception of the one identification information is received by the wireless communication unit, a first non-performing period is set in which the reception of the one identification information is not used for determining the target, and the wireless communication unit sets the first impossible period. After the other identification information is received, a second impossibility period longer than the first impossibility period may be set so that the reception of the other identification information is not used for determining the target.

Further, in the above aspect, the second impossible period may be longer than the period obtained by multiplying the first impossible period by the number of times.

Further, in the above aspect, when the control unit receives one identification information a plurality of times without receiving other identification information different from the one identification information, the vehicle-mounted vehicle that transmits the one identification information is transmitted. The vessel may be determined as the target.

Further, in the above aspect, in the control unit, the wireless communication unit receives each of the plurality of identification information transmitted from each of the plurality of vehicle-mounted devices, and the one identification information is received before the other identification information. When it is received a plurality of times, the vehicle-mounted device that has transmitted the above-mentioned identification information may be determined as the target.

Further, in the above aspect, the identification information may be WCN.

Further, in the above aspect, the information communication process may be an authentication process for collating the registered WCN with the WCN received from the vehicle-mounted device by the wireless communication unit.

Further, the vehicle-mounted device of another aspect of the present invention performs wireless communication with a roadside unit that determines the vehicle-mounted device as a target of information communication processing when the identification information for identifying the vehicle-mounted device is received a plurality of times. To control the wireless communication unit and identify the own unit according to a request signal transmitted from the roadside unit when the wireless communication unit and the own device enter the wireless communication area of the roadside unit. It is provided with a control unit that transmits the identification information of the above multiple times.

Further, the on-board unit communication system of another aspect of the present invention includes the roadside unit of the above aspect and the on-board unit of the above aspect.

Further, in the vehicle-mounted device communication method of another aspect of the present invention, when the vehicle enters the wireless communication area formed by the roadside unit provided on the roadside, the vehicle-mounted device is mounted on the vehicle. When the roadside unit transmits a request signal requesting identification information for identifying the device and the roadside unit receives the identification information from the vehicle-mounted device a plurality of times, the vehicle-mounted device that transmits the identification information. Is determined as the target of the information communication processing, and the information communication processing regarding the vehicle-mounted device determined as the target is executed.

Further, in the computer program of another aspect of the present invention, when the vehicle enters the wireless communication area formed by the roadside unit provided on the roadside, the vehicle-mounted device is mounted on the vehicle-mounted device. A transmission means for transmitting a request signal requesting identification information for identification, when the identification information is received a plurality of times from the vehicle-mounted device, the vehicle-mounted device that has transmitted the identification information is determined as a target of information communication processing. The computer is made to function as a determination means and an execution means for executing the information communication process regarding the vehicle-mounted device determined as the target.

According to the present invention, it is possible to prevent erroneous communication while suppressing the number of antennas.

The schematic diagram which shows the structure of the vehicle-mounted device communication system which concerns on Embodiment 1. FIG. The block diagram which shows the structure of the vehicle-mounted device which concerns on Embodiment 1. FIG. The block diagram which shows the structure of the roadside machine which concerns on Embodiment 1. FIG. The schematic diagram which shows the structure of the vehicle management database. The schematic diagram which shows the frame structure in DSRC wireless communication. The flowchart which shows the communication procedure by the on-board unit communication system which concerns on Embodiment 1. A flowchart showing the procedure of the authentication process. The figure which shows an example of the entry of a vehicle into the wireless communication area of a roadside machine. FIG. 5 is a sequence diagram showing an operation flow in the example shown in FIG. 8 of the on-board unit communication system according to the first embodiment. The schematic diagram which shows the example which two vehicles entered into the wireless communication area of a roadside machine. The flowchart which shows the communication procedure by the roadside machine which concerns on Embodiment 2. FIG. 5 is a sequence diagram showing an operation flow in the example shown in FIG. 10 of the on-board unit communication system according to the second embodiment. The block diagram which shows the structure of the roadside machine which concerns on Embodiment 3. The flowchart which shows the communication procedure by the roadside machine which concerns on Embodiment 3. FIG. 5 is a sequence diagram showing an operation flow in the example shown in FIG. 10 of the on-board unit communication system according to the third embodiment. The flowchart which shows the communication procedure by the roadside machine which concerns on Embodiment 4. FIG. 5 is a sequence diagram showing an operation flow in the example shown in FIG. 10 of the on-board unit communication system according to the fourth embodiment.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. It should be noted that each of the embodiments shown below exemplifies a method and an apparatus for embodying the technical idea of the present invention, and the technical idea of the present invention is not limited to the following. do not have. The technical idea of the present invention can be modified in various ways within the technical scope described in the claims.

(Embodiment 1)
In the present embodiment, the roadside unit and the on-board unit mounted on the vehicle entering the wireless communication area of the roadside unit perform DSRC communication, and the roadside unit performs DSRC communication a plurality of times on the WCN (Wireless Call Number) of the on-board unit. When the in-vehicle device is continuously received, the in-vehicle device is determined as the target of the authentication process, and the authentication process using WCN is executed.

<Configuration of on-board unit communication system>
FIG. 1 is a schematic diagram showing a configuration of an on-board unit communication system according to the present embodiment. As shown in FIG. 1, the on-board unit communication system 100 includes an on-board unit 200, a roadside unit 300, and a vehicle management database (vehicle management DB) 400. The on-board unit 200 is mounted on the vehicle 210, and the roadside unit 300 is installed at the entrance / exit gate 500 of the contract vehicle parking lot. Contract vehicle parking lots include monthly parking lots for which users (vehicles) are fixed, parking lots for residents in condominiums, parking lots for employees of business establishments, factories, etc. Wireless communication by DSRC is possible between the on-board unit 200 and the roadside unit 300. The roadside machine 300 and the vehicle management DB 400 are connected to the communication network 600 and can communicate with each other.

The entrance / exit gate 500 includes an opening / closing gate bar or an elevating chain, and is installed at the entrance / exit of the parking lot. A roadside machine 300 is installed at the entrance / exit gate 500. The roadside machine 300 executes an authentication process for determining whether or not the vehicle is a registered vehicle using WCN when the vehicle 210 passes through the gate. In addition, instead of a gate-type parking lot, a light or display device is set at the entrance and exit, and the entry / exit instruction is given to the vehicle by turning on the light or displaying the vehicle entry / exit instruction on the display device. It is also possible to install the on-board unit communication system 100 in the parking lot having the given configuration.

FIG. 2 is a block diagram showing the configuration of the vehicle-mounted device 200. The on-board unit 200 is an ETC (Electronic Toll Collection System) on-board unit and has a DSRC communication function. The on-board unit 200 includes a control unit 201, an antenna 202, a wireless communication unit 203, and a card reading unit 204.

The control unit 201 has a CPU and a memory, and controls each unit of the vehicle-mounted device 200. The wireless communication unit 203 is a communication module that enables wireless communication by DSRC, and is connected to the antenna 202. The wireless communication unit 203 stores WCN, which is identification information of the own device. The card reading unit 204 is an ETC card reading device, and when the ETC card is inserted, the ETC card information stored in the card can be read.

FIG. 3 is a block diagram showing the configuration of the roadside machine 300. The roadside unit 300 is an ETC roadside unit and has a DSRC communication function and a wired communication function. The roadside machine 300 includes a control unit 301, an antenna 302, a wireless communication unit 303, and a wired communication unit 304.

The wireless communication antenna 302 is installed at the tip of a pole 501 provided near the entrance / exit gate 500 (see FIG. 1). Although the pole is used here, the location of the pole 501 does not matter as long as a wireless communication area of an appropriate size can be formed in front of the entrance / exit gate 500. For example, the antenna 302 can be installed on the wall surface of the building, the housing of the entrance / exit gate 500, or the arched gantry.

The control unit 301 has a CPU and a memory 306, and the memory 306 stores an on-board unit communication program 305 for communicating with the on-board unit 200. The control unit 301 controls each unit of the roadside unit 300 and executes the vehicle-mounted device communication program 305 to execute communication processing with the vehicle-mounted device 200 as described later. The wireless communication unit 303 is a communication module that enables wireless communication by DSRC, and is connected to the antenna 302. The wired communication unit 304 can communicate with another device (specifically, the vehicle management DB 400) connected to the communication network 600 via the communication network 600.

FIG. 4 is a schematic view showing the structure of the vehicle management DB 400. In the vehicle management DB 400, the WCN, the vehicle number (vehicle registration number), and the name of the owner of the vehicle are stored in association with each other. The vehicle whose information is registered in the vehicle management DB 400 is a vehicle that is permitted to park in the parking lot. That is, in the authentication process, the roadside machine 300 makes an inquiry to the vehicle management DB 400 using the WCN as a key, and if there is a reply that the WCN is registered in the vehicle management DB 400, it is authenticated as a conforming vehicle and the WCN is registered. If there is no answer, it will be rejected as a non-conforming vehicle.

<Operation of on-board unit communication system>
Next, the operation of the on-board unit communication system according to the present embodiment will be described. The roadside unit 300 radiates radio waves from the antenna 302 to form a wireless communication area in front of the entrance / exit gate 500. DSRC wireless communication by the TDMA (Time Division Multiple Access) method is performed between the roadside unit 300 and the on-board unit 200 in the wireless communication area. FIG. 5 is a schematic diagram showing a frame configuration in DSRC wireless communication. The frame transmitted by such DSRC wireless communication includes slots such as FCMS (Flame Control Message Slot), MDS (Message Data Slot), WCNS (Wireless Call Number Slot), and ACTS (Activation Slot). As shown in FIG. 5, the downlink is composed of FCMS and a plurality of MDS. The FCMS is a slot for transmitting FCMC (Flame Control Message Channel) including frame control information and slot allocation information, and is positioned at the beginning of a frame. The MDS is a slot for data transmission. The uplink selectively includes MDS, ACTS, WCNS and the like. The ACTS is a slot for transmitting an ACTC (Activation Channel), which is a connection request signal to the roadside machine 300, and the WCNS is a slot for transmitting WCN.

FIG. 6 is a flowchart showing a communication procedure by the on-board unit communication system according to the present embodiment. The control unit 301 of the roadside machine 300 periodically transmits the FCMC by the wireless communication unit 303 (step S101). When the vehicle 210 enters the wireless communication area of the roadside machine 300, the on-board unit 200 of the vehicle 210 receives the FCMC (step S102). The control unit 201 of the vehicle-mounted device 200 that has received the FCMC transmits the ACTC by the wireless communication unit 203 (step S103), and the roadside unit 300 receives this (step S104). After that, the roadside unit 300 transmits the BST (Beacon Service Table) to the in-vehicle device 200, the in-vehicle device 200 transmits the VST (Vehicle Service Table) to the roadside unit 300, and other necessary communication is performed. Control unit 301 transmits a WCN request signal requesting WCN to the vehicle-mounted device 200 (step S105). When the control unit 201 of the vehicle-mounted device 200 receives the WCN request signal (step S106), it reads out the WCN of its own device (step S107) and transmits it to the roadside unit 300 (step S108).

When the control unit 301 of the roadside machine 300 receives the WCN (step S109), it determines whether or not the monitoring period for monitoring the WCN is in progress (step S110). The monitoring period is a period for monitoring the reception of a specific WCN. When the monitoring period has ended or the monitoring period has not been set up to that point (NO in step S110), the control unit 301 stores the WCN as a processing target candidate in the memory 306 (step S111) and receives the WCN. The initial value "1" is set in the WCN counter i in the memory 306, which is a variable indicating the number of times (step S112). The memory 306 is provided with only one WCN counter i.

Next, the control unit 301 sets a monitoring period and starts it (step S113). At this time, if the monitoring period is set at that time, the monitoring period is invalidated and a new monitoring period is started. Further, the control unit 301 transmits a release timer to the vehicle-mounted device 200, which is a non-use period during which the reception of the WCN is not used for determining the authentication process (step S114). When the vehicle-mounted device 200 receives the release timer (YES in step S115), the control unit 201 sets the release timer and starts it (step S116). The on-board unit 200 does not respond to the communication from the roadside unit 300 during the period in which the release timer is set. If the on-board unit 200 does not receive the release timer (NO in step S115), the control unit 201 returns the process to step S102 and repeats the process after receiving the FCMC.

Here, the monitoring period is set longer than the release timer. Further, in the present embodiment, the relationship between the monitoring period WT and the release timer RT is defined by the following equation.
WT> RT × (N-1)
Further, more preferably, the WT can be defined as follows.
WT ≧ RT × N
Specifically, the WT is preferably set longer than 200 milliseconds. However, if the WT is made too long, the communication time between the roadside unit 300 and the on-board unit 200 becomes long. Therefore, the WT is preferably set to 2000 milliseconds or less.

On the other hand, when the monitoring period is in progress, that is, when the reception of the WCN of the processing target candidate is monitored (YES in step S110), the control unit 301 has previously received the processing target and stored in the memory 306. It is determined whether or not the candidate WCN and the WCN received this time match (step S117). Here, if the WCN of the processing target candidate is not stored in the memory 306, it is determined that they do not match. If the WCN of the processing target candidate and the received WCN do not match, that is, the reception of the WCN is the first (NO in step S117), the control unit 301 shifts the processing to step S111 and moves to the memory 306. The WCN is overwritten and saved as a new processing target candidate (step S111), and the initial value "1" is set in the WCN counter i in the memory 306 (that is, the WCN counter i is reset) (step S112). After that, in the same manner as described above, the control unit 301 executes the processes of steps S113 and S114.

After transmitting the release timer, the control unit 301 of the roadside machine 300 returns the process to step S101, and executes the process after the transmission of the FCMC again. On the other hand, after setting the release timer, the control unit 201 of the vehicle-mounted device 200 determines whether or not the release timer has ended (step S118), and if it has not ended (NO in step S118), the process of step S118. repeat. When the release timer ends (YES in step S118), the control unit 201 returns the process to step S102, and executes the process after receiving the FCMC again.

When the WCN of the processing target candidate stored in the memory and the received WCN match, that is, when the same WCN is received twice or more, the control unit 301 of the roadside machine 300 (in step S117). YES), the value of the WCN counter i is incremented by one (step S119), and it is determined whether or not the value of the WCN counter i matches the preset specified number of receptions N (step S120). When the value of the WCN counter i does not match the specified number of receptions N (NO in step S120), the control unit 301 shifts the process to step S114, transmits the release timer again (step S114), and then moves to step S101. return.

On the other hand, when the value of the WCN counter i matches the specified number of receptions N (YES in step S120), the control unit 301 is identified by the WCN of the processing target candidate stored in the memory 306 (that is, the WCN). The on-board unit 200) is determined as the target of the authentication process (step S121), and the processing target candidates are reset (step S122). As a result, the WCN that is the target of the authentication process is deleted from the processing target candidates of the memory 306. The control unit 301 monitors the elapsed time since the WCN was set as the processing target candidate, and resets the processing target candidate even when the monitoring period elapses while the WCN is set as the processing target candidate. do. After step S122, the control unit 301 executes the authentication process (step S123). The details of the authentication process will be described later. After the authentication process, the control unit 301 shifts the process to step S114, transmits the release timer again (step S114), and returns the process to step S101. The above is the communication process between the roadside unit 300 and the on-board unit 200. After that, the FCMC will be transmitted from the roadside unit 300, but since it is not necessary to receive the WCN that has already been determined as the target of the authentication process, for example, the release timer may be set longer or the WCN may be received. Even if it is ignored, the above-mentioned communication process is not newly performed between the vehicle-mounted device 200 and the roadside device 300, which have already been determined to be the targets of the authentication process.

In the above communication process, in order for the vehicle-mounted device 200 to be determined as the target of the authentication process, the WCN of the vehicle-mounted device 200 must be received by the roadside unit 300 by the specified number of reception times N. Therefore, when the WCN is transmitted from the on-board unit mounted on the vehicle traveling on the road near the roadside unit 300, the time during which this vehicle is traveling in the wireless communication area of the roadside unit 300 is Since it is very short, it is unlikely that the number of receptions of the WCN of the on-board unit mounted on the vehicle will reach the specified number of receptions N, and it is possible to prevent the on-board unit from being determined as the target of the authentication process.

Here, an arbitrary period can be set for the release timer, and the release timer can be set to 0 seconds (that is, the release timer is not set). However, if the release timer is set to 0 seconds, WCN with a specified number of receptions N can be transmitted and received in a very short period of time, and the possibility of erroneous communication as described above increases. Therefore, it is preferable that the release timer is set to a value larger than 0 seconds. Further, if the release timer is set too long, it is conceivable that when the vehicle 210 moves to another roadside machine, communication with this roadside machine cannot be performed. Therefore, in order to prevent such an inconvenience, it is necessary to make the length of the release timer at least shorter than the time required to move to the next roadside machine. Specifically, the length of the release timer is preferably 2000 milliseconds or less.

Further, the roadside unit 300 receives the WCN (hereinafter referred to as “WCN1”) from one on-board unit 200, the WCN1 is stored in the memory 306 as a processing target candidate, the monitoring period is set, and the number of times the WCN1 is received. Is less than the specified number of receptions N, and when the roadside unit 300 receives the WCN (hereinafter referred to as “WCN2”) from the other on-board unit 200, the WCN2 which is a new processing target candidate is overwritten and saved in the memory 306. And the monitoring period and WCN counter i are reset. Therefore, even if the WCN1 is subsequently received by the roadside machine 300 again and the total number of receptions of the WCN1 reaches the specified number of receptions N, the WCN1 is not determined as the target of the authentication process. This means that if the same WCN is not continuously received by the roadside machine 300 for the specified number of receptions N or more, the WCN is not determined as the target of the authentication process.

Next, the authentication process will be described. FIG. 7 is a flowchart showing the procedure of the authentication process. The control unit 301 of the roadside machine 300 reads the WCN determined as the target of the authentication process from the memory 306 (step S131), transmits a verification request signal (query) including this WCN as a key to the vehicle management DB 400, and performs verification. Request (step S132). The vehicle management DB 400 receives the collation request signal, collates the WCN included in the collation request signal with the registered WCN, and transmits the collation result as a response signal. When the control unit 301 of the roadside machine 300 receives the response signal (step S133), the control unit 301 determines whether or not the authentication is successful based on the response signal (step S134), and the authentication is successful, that is, the WCN is sent to the vehicle management DB 400. If it is registered (YES in step S134), a gate opening instruction signal is transmitted to the control unit of the entrance / exit gate 500 (step S135), and the authentication process ends. On the other hand, if the authentication fails, that is, if the WCN is not registered in the vehicle management DB 400 (NO in step S134), the control unit 301 does not send a gate opening instruction signal to the control unit of the entrance / exit gate 500. End the authentication process. As a result, if the authentication fails, the entrance / exit gate 500 remains closed and the vehicle 210 is denied passage through the gate.

Next, the operation of the on-board unit communication system 100 according to the present embodiment will be described with reference to a specific example. FIG. 8 is a diagram showing an example of the vehicle 210 entering the wireless communication area of the roadside unit 300, and FIG. 9 is a sequence diagram showing the operation flow of the on-board unit communication system 100 in this example. In this example, the monitoring period WT is 400 milliseconds, the release timer RT is 200 milliseconds, and the specified number of receptions N is 2.

When one vehicle 210 trying to enter the parking lot stops in front of the entrance / exit gate 500, the on-board unit 200 mounted on the vehicle 210 is in the wireless communication area 350 of the roadside unit 300. First, the vehicle-mounted device 200 receives the FCMC transmitted from the roadside unit 300, and the roadside unit 300 receives the ACTC transmitted from the vehicle-mounted device 200 accordingly (steps S101a to S104a). After the BST and VST are transmitted and received, the roadside unit 300 makes the first WCN request, and the on-board unit 200 receives the request and performs the first WCN transmission (steps S105a to S108a). When the roadside machine 300 receives the first WCN (step S109a), the monitoring period WT is set (step S113). Further, the roadside machine 300 transmits the release timer RT, and the vehicle-mounted device 200 receives the release timer RT to set the release timer RT (steps S114a to S116a).

After the roadside machine 300 transmits the release timer RT, the FCMC is periodically transmitted again (step S101), but since the release timer RT is set in the vehicle-mounted device 200, the vehicle-mounted device 200 responds to the FCMC. There is no. When the release timer RT ends, the vehicle-mounted device 200 transmits the ACTC in response to the FCMC transmitted from the roadside unit 300, and the roadside unit 300 receives this (steps S101b to S104b). After the BST and VST are transmitted and received, the roadside unit 300 makes a second WCN request, and the on-board unit 200 receives the request and performs the second WCN transmission (steps S105b to S108b). Since the monitoring period WT has not ended at this point, when the roadside machine 300 receives the second WCN (step S109a), it determines the WCN as the target of the authentication process (step S121) and executes the authentication process (step S121). Step S123).

(Embodiment 2)
FIG. 10 is a schematic view showing an example in which two vehicles have entered the wireless communication area 350 of the roadside machine 300. As shown in FIG. 10, when two vehicles 210a and 210b stop side by side in front of the entrance / exit gate 500, these two vehicles 210a and 210b are in the wireless communication area 350 of the roadside unit 300. There is. In such a case, in the conventional system, the roadside unit 300 communicates with the on-board unit 200b mounted on the following vehicle 210b instead of communicating with the on-board unit 200a mounted on the preceding vehicle 210a. Miscommunication may occur. Therefore, the on-board unit communication system according to the present embodiment executes communication processing that can prevent erroneous communication even in the above case. In the present embodiment, when a plurality of vehicles enter the wireless communication area of the roadside unit, a short release timer is set for one on-board unit (first on-board unit), and another on-board unit (first on-board unit) is set. Set a long release timer for 2 on-board units).

<Configuration of on-board unit communication system>
Since the configuration of the on-board unit communication system according to the present embodiment is the same as the configuration of the on-board unit communication system 100 according to the first embodiment, the same components are designated by the same reference numerals and the description thereof will be omitted.

<Operation of on-board unit communication system>
The operation of the on-board unit communication system 100 according to the present embodiment will be described. FIG. 11 is a flowchart showing a communication procedure by the roadside machine 300 according to the present embodiment. The communication procedure by the vehicle-mounted device 200 is the same as that described in the first embodiment.

The control unit 301 of the roadside machine 300 periodically transmits FCMC (step S101), and receives ACTC when it is transmitted from the vehicle-mounted device 200 (step S104). Further, when the control unit 301 transmits a WCN request signal to the vehicle-mounted device 200 (step S105) and receives the WCN (step S109), it determines whether or not the monitoring period is in progress (step S110).

When the monitoring period has ended or the monitoring period has not been set up to that point (NO in step S110), the control unit 301 stores the received WCN in the memory 306 as a priority WCN (step S211). Here, the priority WCN is a target WCN that is preferentially monitored over other WCNs when a plurality of WCNs are received in competition, and the other WCNs are other than the priority WCNs. A release timer shorter than WCN is set.

Next, the control unit 301 stores the WCN as a processing target candidate in the memory 306 (step S111), and sets the initial value “1” in the WCN counter i (step S112). Further, the control unit 301 sets a monitoring period and starts the monitoring period (step S113).

Next, the control unit 301 determines whether or not the processing target candidate matches the priority WCN (step S214). When the processing target candidate matches the priority WCN (YES in step S214), the first release timer is transmitted to the on-board unit 200 (step S215), and when the processing target candidate does not match the priority WCN (step S214). NO), the second release timer is transmitted to the vehicle-mounted device 200 (step S216). Here, the first release timer is a release timer shorter than the second release timer. Further, in the present embodiment, _{the relationship between the first release timer RT 1} and the second release timer RT ₂ is defined by the following equation.
RT ₂ > RT ₁ x (N-1)
Further, more preferably, RT ₂ can be defined as follows.
RT ₂ ≧ RT ₁ × N
A suitable range for the first release timer RT ₁ is 200 ms ≤ RT ₁ ≤ 1000 ms. However, the first release timer RT ₁ can be set to 0 seconds (that is, the first release timer is not set). In this case, since it is considered that the number of WCN receptions reaches the specified number of receptions in a short period of time, it is sufficient that the length of _{the second release timer RT 2 is at least 200 milliseconds.} Further, in order to prevent the communication time from becoming too long, the _{length of the second release timer RT 2} is preferably 2000 milliseconds or less. Further, since the length of the monitoring period WT is the same as that described in the first embodiment, the description thereof will be omitted. After transmitting the release timer (that is, the first release timer or the second release timer), the control unit 301 returns the process to step S101, and executes the process after the transmission of the FCMC again.

On the other hand, when the monitoring period is in progress, that is, when the reception of the WCN of the processing target candidate is monitored (YES in step S110), the control unit 301 determines whether or not the processing target candidate and the received WCN match. (Step S117). If the processing target candidate and the received WCN do not match (NO in step S117), the control unit 301 shifts the processing to step S111, overwrites and saves the WCN as a new processing target candidate in the memory 306, and saves the WCN as a new processing target candidate (NO). Step S111), the WCN counter i in the memory 306 is set to the initial value “1” (that is, the WCN counter i is reset) (step S112). After that, in the same manner as described above, the control unit 301 executes the processes of steps S113 and S214 to S216.

When the processing target candidate and the received WCN match, that is, when the same WCN is received twice or more (YES in step S117), the control unit 301 of the roadside machine 300 sets the value of the WCN counter i. Is incremented by one (step S119), and it is determined whether or not the value of the WCN counter i matches the specified number of receptions N (step S120). When the value of the WCN counter i does not match the specified number of receptions N (NO in step S120), the control unit 301 shifts the processing to step S214 and determines whether or not the processing target candidate matches the priority WCN (step). S214), the first or second release timer is transmitted according to the determination result (steps S215 and S216).

On the other hand, when the value of the WCN counter i matches the specified number of receptions N (YES in step S120), the control unit 301 determines the WCN of the processing target candidate as the target of the authentication process (step S121), and the priority WCN. And reset the processing target candidate (step S222). As a result, the WCN is deleted from the priority WCN and the processing target candidates. The control unit 301 monitors the elapsed time since the WCN was set to the priority WCN, and resets the priority WCN even when the monitoring period elapses while the WCN is set to the priority WCN. The reset of the processing target candidate is the same as that described in the first embodiment.

After step S222, the control unit 301 executes the authentication process (step S123). Since the authentication process is the same as that described in the first embodiment, the description thereof will be omitted. After the authentication process, the control unit 301 shifts the process to step S215, transmits the first release timer to the vehicle-mounted device 200 (step S215), and returns the process to step S101. The above is the communication processing of the roadside machine 300 according to the present embodiment. After that, the FCMC will be transmitted from the roadside unit 300, but since it is not necessary to receive the WCN from the on-board unit 200 that has already been determined as the target of the authentication process, for example, the release timer may be set longer. By ignoring the WCN even if it is received, the above-mentioned communication process is not newly performed between the on-board unit 200 and the roadside unit 300 that have already been determined as the target of the authentication process. To.

Next, the operation of the on-board unit communication system 100 according to the present embodiment will be described with reference to the example shown in FIG. FIG. 12 is a sequence diagram showing an operation flow of the on-board unit communication system 100 in the example shown in FIG. In the following description, the WNC of the on-board unit 200a mounted on the vehicle 210a is referred to as WNC1, and the WNC of the on-board unit 200b mounted on the vehicle 210b is referred to as WNC2. Further, in this example, the monitoring period WT is 400 milliseconds, the first release timer RT ₁ is 200 milliseconds, the second release timer RT ₂ is 500 milliseconds, and the specified number of receptions N is 2.

As shown in FIG. 10, it is assumed that the two vehicles 210a and 210b are in the wireless communication area 350 of the roadside unit 300. First, the on-board unit 200a mounted on the vehicle 210a receives the FCMC transmitted from the roadside unit 300, and the roadside unit 300 receives the ACTC transmitted from the on-board unit 200a accordingly (steps S101a to S104a). After the BST and VST are transmitted and received, the roadside unit 300 makes the first WCN request, and the on-board unit 200a receives this and transmits the first WCN1 (steps S105a to 108a). When the roadside machine 300 receives the first WCN1 (step S109a), since the monitoring period WT is not set at this point, the WCN1 is set as the priority WCN and the processing target candidate. Further, the roadside machine 300 sets the monitoring period WT (step S113a).

At this point, each of the priority WCN and the processing target candidate is WCN1, and both are in agreement. Therefore, the roadside machine 300 _{transmits the first release timer RT 1} , and the vehicle-mounted device 200a receives the first release timer RT ₁ to set the first release timer RT 1 (steps S215a, S115a, S116a).

After transmitting the first release timer RT ₁ , the roadside unit 300 periodically transmits the FCMC again, but since the first release timer RT ₁ is set in the on-board unit 200a, the on-board unit 200a responds to the FCMC. There is nothing to do. However, the release timer is not set in the on-board unit 200b, and the on-board unit 200b responds to the FCMC transmitted from the roadside unit 300. As a result, the on-board unit 200b transmits WCN2, which is its own WCN (steps S101b to S108b).

When the roadside machine 300 receives the WCN2 (step S109b), it is determined whether or not the WCN2 matches the processing target candidate because the monitoring period WT is in progress. Since the processing target candidate at this point is WCN1, the new processing target candidate WCN2 is overwritten and saved, the WCN counter i is reset, and the monitoring period WT is reset (step S113b).

The roadside machine 300 determines whether or not the processing target candidate and the priority WCN match. At this point, the processing target candidate WCN2 and the priority WCN are WCN1, and they do not match. Therefore, the roadside machine 300 _{transmits the second release timer RT 2} to the vehicle-mounted device 200b, and the vehicle-mounted device 200b receives the second release timer RT ₂ to set the second release timer RT 2 (steps S216b, S115b, S116b).

After the roadside machine 300 _{transmits the second release timer RT 2} , the FCMC is periodically transmitted again (step S101), but since the second release timer RT ₂ is set on the on-board unit 200b, the on-board unit 200b is set on the FCMC. The vessel 200b does not respond. _{After that, the first release timer RT 1} of the on-board unit 200a, which is set earlier and _{is shorter than the second release timer RT 2} , ends, and FCMC, ACTC transmission / reception, WCN request, and WCN 1 transmission are performed again ( Steps S101c to S108c). Although the WCN1 is transmitted for the second time, even if the roadside unit 300 receives the WCN1 (step S109c), the WCN counter i has already been reset, so that the on-board unit 200a is determined to be the target of the authentication process. do not have. Since the monitoring period WT is in progress at this point, the roadside machine 300 determines whether or not WCN1 matches the processing target candidate. Since the processing target candidate at this point is WCN2, the new processing target candidate WCN1 is overwritten and saved, the WCN counter i is reset, and the monitoring period WT is reset (step S113c). The on-board unit 200a transmits WCN1 twice, and the value of the WCN counter i at this point is "1".

The roadside machine 300 determines whether or not the processing target candidate and the priority WCN match. At this point, both the processing target candidate and the priority WCN are WCN1, and both are in agreement. Therefore, the roadside unit 300 _{transmits the first release timer RT 1} to the vehicle-mounted device 200a, and the vehicle-mounted device 200a receives the first release timer RT ₁ to set the first release timer RT 1 (steps S215c, S115c, S116c).

After transmitting the first release timer RT ₁ , the roadside machine 300 periodically transmits the FCMC again (step S101), but since the first release timer RT ₁ is set in the on-board unit 200a, the on-board unit 200a is set on the FCMC. The vessel 200a does not respond. Here, the first release timer RT ₁ ends first, and the second release timer RT ₂ longer than this does not end. Therefore, FCMC, ACTC transmission / reception, WCN request, and WCN1 transmission / reception are performed again between the roadside unit 300 and the on-board unit 200a (steps S101d to S109d).

Since the monitoring period WT is in progress at this point, the roadside machine 300 determines whether or not WCN1 matches the processing target candidate. Since the processing target candidate at this point is WCN1, the WCN counter i becomes “2”, which matches the specified number of receptions N. Therefore, the roadside machine 300 determines WCN1 as the target of the authentication process (step S121) and executes the authentication process (step S123).

By the structure described above, the vehicle 210a, 210b is when entering the radio communication area 350 of the roadside device 300 sets a shorter first release timer RT ₁ is for one of the vehicle-mounted device 200a, other OBE are setting the long second release timer RT ₂ for 200b, erroneous communication with the vehicle-mounted device 200b of the second release timer RT ₂ is set to prevent the provisions receive WCN1 of the vehicle-mounted device 200a It can be received more than the number of times, and the on-board unit 200a can be determined as the target of the authentication process.

(Embodiment 3)
In the present embodiment, the radio field strength of each of the radio signals transmitted from the plurality of on-board units is detected, and a short release timer is set for one on-board unit (first on-board unit) having a high radio wave strength. Set a long release timer for other on-board units (second on-board units) with low signal strength. By using the radio wave strength of the received signal that reflects the distance of the communication partner, priority is given to communication with the first on-board unit that is close to the roadside unit 300, and erroneous communication with the second on-board unit is effectively performed. To prevent.

<Configuration of on-board unit communication system>
First, the configuration of the on-board unit communication system according to the present embodiment will be described. FIG. 13 is a block diagram showing a configuration of a roadside machine according to the present embodiment. In the present embodiment, the roadside unit 330 includes a detection unit 307 that detects the radio wave intensity of the received signal in the wireless communication unit 303. The detection unit 307 is an RSSI (Received Signal Strength Indicator), and outputs an RSSI (Received Signal Strength Indication) value indicating the radio wave strength of the detected received signal to the control unit 301. Since the other configurations of the on-board unit communication system according to the present embodiment are the same as the configurations of the on-board unit communication system 100 according to the first embodiment, the same components are designated by the same reference numerals and the description thereof will be described. Omit.

<Operation of on-board unit communication system>
The operation of the on-board unit communication system according to the present embodiment will be described. FIG. 14 is a flowchart showing a communication procedure by the roadside unit 330 according to the present embodiment. The communication procedure by the vehicle-mounted device 200 is the same as that described in the first embodiment.

The control unit 301 of the roadside unit 330 periodically transmits FCMC (step S101), and receives ACTC when it is transmitted from the vehicle-mounted device 200 (step S104). The detection unit 307 detects the radio field intensity of the ACTC and outputs the RSSI value. As a result, the control unit 301 acquires the RSSI value (step S305).

Further, when the control unit 301 transmits a WCN request signal to the vehicle-mounted device 200 (step S105) and receives the WCN (step S109), it determines whether or not the monitoring period is in progress (step S110).

When the monitoring period has ended or the monitoring period has not been set up to that point (NO in step S110), the control unit 301 sets the previous value, which is a variable in the memory 306 indicating the previously acquired RSSI value, to "0". "(Step S311).

Next, the control unit 301 stores the WCN as a processing target candidate in the memory 306 (step S111), and sets the initial value “1” in the WCN counter i (step S112). Further, the control unit 301 sets a monitoring period and starts the monitoring period (step S113).

Next, the control unit 301 compares the acquired RSSI value with the previous value, and determines whether or not the RSSI value is larger than the previous value (step S314). In the present embodiment, the WCN transmitted from the vehicle-mounted device having a large RSSI value is monitored with priority over the WCN transmitted from the vehicle-mounted device having a small RSSI value. Specifically, a release timer shorter than other WCNs is set for the priority WCN. That is, when the RSSI value is larger than the previous value (YES in step S314), the first release timer is transmitted to the on-board unit 200 (step S315), and when the RSSI value is equal to or less than the previous value (in step S314). NO), the second release timer is transmitted to the vehicle-mounted device 200 (step S316). Here, the first release timer is a release timer shorter than the second release timer. Since the relationship between the first release timer RT ₁ and the second release timer RT _{2 in} the present embodiment is the same as that described in the first embodiment, the description thereof will be omitted. After transmitting the release timer (that is, the first release timer or the second release timer), the control unit 301 sets the current RSSI value to the previous value (step S317). After that, the control unit 301 returns the process to step S101, and executes the process after the transmission of the FCMC again.

On the other hand, when the monitoring period is in progress, that is, when the reception of the WCN of the processing target candidate is monitored (YES in step S110), the control unit 301 determines whether or not the processing target candidate and the received WCN match. (Step S117). If the processing target candidate and the received WCN do not match (NO in step S117), the control unit 301 shifts the processing to step S111, overwrites and saves the WCN as a new processing target candidate in the memory 306, and saves the WCN as a new processing target candidate (NO). Step S111), the WCN counter i in the memory 306 is set to the initial value “1” (that is, the WCN counter i is reset) (step S112). After that, in the same manner as described above, the control unit 301 executes the processes of steps S113 and S314 to S317.

The control unit 301 increments the value of the WCN counter i by one when the processing target candidate and the received WCN match, that is, when the same WCN is received twice or more (YES in step S117). (Step S119), it is determined whether or not the value of the WCN counter i matches the specified number of receptions N (step S120). When the value of the WCN counter i does not match the specified number of receptions N (NO in step S120), the control unit 301 shifts the process to step S315, transmits the first release timer to the vehicle-mounted device 200 (step S315), and steps. The process is returned to S101.

On the other hand, when the value of the WCN counter i matches the specified number of receptions N (YES in step S120), the control unit 301 determines the WCN of the processing target candidate as the target of the authentication process (step S121), and the processing target. The candidates are reset (step S122). As a result, WCN is deleted from the processing target candidates. The resetting of the processing target candidates is the same as that described in the first embodiment.

After step S122, the control unit 301 executes the authentication process (step S123). Since the authentication process is the same as that described in the first embodiment, the description thereof will be omitted. After the authentication process, the control unit 301 shifts the process to step S315, transmits the first release timer to the vehicle-mounted device 200 (step S315), and returns the process to step S101. The above is the communication processing of the roadside unit 330 according to the present embodiment. After that, FCMC will be transmitted from the roadside unit 330, but since it is not necessary to receive WCN from the on-board unit 200 that has already been determined as the target of the authentication process, for example, the release timer may be set longer. By ignoring the WCN even if it is received, the above-mentioned communication process is not newly performed between the on-board unit 200 and the roadside unit 330 that have already been determined as the target of the authentication process. To.

Next, the operation of the on-board unit communication system 100 according to the present embodiment will be described with reference to the example shown in FIG. FIG. 15 is a sequence diagram showing an operation flow in the example shown in FIG. 10 of the on-board unit communication system according to the present embodiment. In this example, the monitoring period WT is 400 milliseconds, the first release timer RT ₁ is 200 milliseconds, the second release timer RT ₂ is 500 milliseconds, and the specified number of receptions N is 2.

As shown in FIG. 10, it is assumed that the two vehicles 210a and 210b are in the wireless communication area 350 of the roadside unit 330. Here, the case where the on-board unit 200b mounted on the following vehicle 210b responds to the FCMC transmitted from the roadside unit 330 before the on-board unit 200a mounted on the preceding vehicle 210a will be described. First, the on-board unit 200b mounted on the vehicle 210b receives the FCMC transmitted from the roadside unit 330, and the roadside unit 330 receives the ACTC transmitted from the on-board unit 200b accordingly (steps S101b to S104b). The detection unit 307 detects the radio field intensity of the ACTC, and the roadside machine 330 acquires the RSSI value. The RSSI value at this time is defined as RSSIb. Then, after the BST and VST are transmitted and received, the roadside unit 330 makes the first WCN request, and the on-board unit 200a receives this and transmits the first WCN2 (steps S105b to 108b). When the roadside machine 330 receives the first WCN2 (step S109b), since the monitoring period WT is not set at this point, WCN2 is set as a processing target candidate. Further, the roadside machine 330 initializes the previous value to 0 and sets the monitoring period WT (step S113b).

At this point, the previous value is "0", so RSSIb is larger than the previous value. Therefore, the roadside machine 330 _{transmits the first release timer RT 1} , and the vehicle-mounted device 200b receives the first release timer RT ₁ to set the first release timer RT 1 (steps S315b, S115b, S116b). Further, the roadside machine 330 sets RSSIb to the previous value.

After transmitting the first release timer RT ₁ , the roadside unit 330 periodically transmits the FCMC again, but since the first release timer RT ₁ is set in the on-board unit 200b, the on-board unit 200b responds to the FCMC. There is nothing to do. However, the release timer is not set in the on-board unit 200a, and the on-board unit 200a responds to the FCMC transmitted from the roadside unit 330 (steps S101a to 104a). The detection unit 307 detects the radio field intensity of the ACTC as a response of the FCMC, and the roadside unit 330 acquires the RSSI value. The RSSI value at this time is RSSIa, and RSSIa> RSSIb. After that, the on-board unit 200a transmits WCN1 which is the WCN of its own unit (steps S105a to S108a).

When the roadside unit 330 receives the WCN1 (step S109a), since the monitoring period WT is in progress, it is determined whether or not the WCN1 matches the processing target candidate. Since the processing target candidate at this point is WCN2, the new processing target candidate WCN1 is overwritten and saved, the WCN counter i is reset, and the monitoring period WT is reset (step S113a).

The roadside machine 330 compares RSSIA with the previous value. At this point, the previous value is RSSIb, and RSSIa is larger than the previous value. Therefore, the roadside unit 330 _{transmits the first release timer RT 1} to the vehicle-mounted device 200a, receives the first release timer RT ₁ by the vehicle-mounted device 200a, and sets the first release timer RT 1 (steps S315a, S115a, S116a). Further, the roadside machine 330 sets RSSIA to the previous value.

After transmitting the first release timer RT ₁ , the roadside unit 330 periodically transmits the FCMC again, but since the first release timer RT ₁ is set in the on-board unit 200a, the on-board unit 200a responds to the FCMC. There is nothing to do. Then, since the vehicle-mounted device 200a and release timer set to 200b are each a first release timer RT _1, completed first release timer RT ₁ of the vehicle-mounted device 200b previously set again FCMC, ACTC Transmission / reception, acquisition of RSSI value, WCN request, and WCN2 transmission (steps S101d to S108d). For the sake of simplicity, the RSSI value acquired here is referred to as RSSIb.

Although the WCN2 is transmitted for the second time, even if the roadside unit 330 receives the WCN2 (step S109d), the WCN counter i has already been reset, so that the on-board unit 200b is determined to be the target of the authentication process. do not have. Since the monitoring period WT is in progress at this point, the roadside machine 330 determines whether or not WCN2 matches the processing target candidate. Since the processing target candidate at this point is WCN1, the new processing target candidate WCN2 is overwritten and saved, the WCN counter i is reset, and the monitoring period WT is reset (step S113d). The on-board unit 200b transmits WCN2 twice, and the value of the WCN counter i at this point is "1".

The roadside machine 330 compares RSSIb with the previous value. At this point, the previous value is RSSIa, and RSSIb is less than or equal to the previous value. Therefore, the roadside unit 330 _{transmits the second release timer RT 2} to the vehicle-mounted device 200b, and the vehicle-mounted device 200b receives this _{to set the second release timer RT 2} (steps S316a, S115a, S116a). Further, the roadside machine 330 sets RSSIb to the previous value.

After transmitting the second release timer RT ₂ , the roadside unit 330 periodically transmits the FCMC again, but since the second release timer RT ₂ is set in the on-board unit 200b, the on-board unit 200b responds to the FCMC. There is nothing to do. _{After that, the first release timer RT 1} of the on-board unit 200a, which is set earlier and _{shorter than the second release timer RT 2} , ends, and FCMC, ACTC transmission / reception, RSSI value acquisition, WCN request, and WCN 1 again. Transmission is performed (steps S101c to S108c). For the sake of simplicity, the RSSI value acquired here is referred to as RSSIA.

Although the WCN1 is transmitted for the second time, even if the roadside unit 330 receives the WCN1 (step S109c), the WCN counter i has already been reset, so that the on-board unit 200a is determined to be the target of the authentication process. do not have. Since the monitoring period WT is in progress at this point, the roadside machine 330 determines whether or not WCN1 matches the processing target candidate. Since the processing target candidate at this point is WCN2, the new processing target candidate WCN1 is overwritten and saved, the WCN counter i is reset, and the monitoring period WT is reset (step S113c). The on-board unit 200a transmits WCN1 twice, and the value of the WCN counter i at this point is "1".

The roadside machine 330 compares RSSIA with the previous value. At this point, the previous value is RSSIb, and RSSIa is larger than the previous value. Therefore, the roadside unit 330 _{transmits the first release timer RT 1} to the vehicle-mounted device 200a, and the vehicle-mounted device 200a receives this _{to set the first release timer RT 1} (steps S315c, S115c, S116c). Further, the roadside machine 330 sets RSSIA to the previous value.

After transmitting the first release timer RT ₁ , the roadside unit 330 periodically transmits the FCMC again, but since the first release timer RT ₁ is set in the on-board unit 200a, the on-board unit 200a responds to the FCMC. There is nothing to do. Here, the first release timer RT ₁ ends first, and the second release timer RT ₂ longer than this does not end. Therefore, FCMC, ACTC transmission / reception, RSSI value acquisition, WCN request, and WCN1 transmission / reception are performed again between the roadside unit 330 and the on-board unit 200a (steps S101e to S109e).

Since the monitoring period WT is in progress at this point, the roadside machine 330 determines whether or not WCN1 matches the processing target candidate. Since the processing target candidate at this point is WCN1, the WCN counter i becomes “2”, which matches the specified number of receptions N. Therefore, the roadside machine 330 determines WCN1 as the target of the authentication process (step S121) and executes the authentication process (step S123).

Due to the above configuration, the radio wave strength (RSSIa) in the received signal from the on-board unit 200a close to the roadside unit 330 is larger than the radio wave strength (RSSIa) in the received signal from the on-board unit 200b away from the roadside unit 330. _{Therefore, a short first release timer RT 1} should be set for the on-board unit 200a having a large _{RSSI value, and a long second release timer RT 2} should be set for the on-board unit 200b having a small RSSI value. Therefore, erroneous communication with the on-board unit 200b in which the second release timer RT ₂ is set can be prevented, WCN1 of the on-board unit 200a can be received more than the specified number of receptions, and the on-board unit 200a is determined as the target of the authentication process. can do.

(Embodiment 4)
In the present embodiment, the continuous reception of WCN is not set as the determination condition of the target of the authentication process, but when a plurality of WCNs are received in competition, the number of receptions of WCN reaches the specified number of receptions first. The on-board unit is determined as the target of the authentication process.

<Configuration of on-board unit communication system>
Since the configuration of the on-board unit communication system according to the present embodiment is the same as the configuration of the on-board unit communication system 100 according to the first embodiment, the same components are designated by the same reference numerals and the description thereof will be omitted.

<Operation of on-board unit communication system>
The operation of the on-board unit communication system 100 according to the present embodiment will be described. FIG. 16 is a flowchart showing a communication procedure by the roadside machine 300 according to the present embodiment. The communication procedure by the vehicle-mounted device 200 is the same as that described in the first embodiment.

The control unit 301 of the roadside machine 300 periodically transmits FCMC (step S101), and receives ACTC when it is transmitted from the vehicle-mounted device 200 (step S104). Further, when the control unit 301 transmits a WCN request signal to the vehicle-mounted device 200 (step S105) and receives the WCN (step S109), it determines whether or not the monitoring period is in progress (step S110).

When the monitoring period has ended or the monitoring period has not been set up to that point (NO in step S110), the control unit 301 sets the monitoring period and starts it (step S411). Next, the control unit 301 stores the received WCN in the memory 306 as a priority WCN (step S412). Since the priority WCN is the same as that described in the second embodiment, the description thereof will be omitted.

Next, the control unit 301 deletes all the WCNs to be monitored stored in the memory 306 (step S413), and sets the received WCNs as new monitoring targets by storing them in the memory 306 (step S413). S414). Here, the monitoring target means a WCN to be monitored for the number of receptions during the monitoring period. Next, the control unit 301 _{defines the WCN counter i WCN} corresponding to the received WCN (step S415), and sets the initial value “1” in the _{WCN counter i WCN (step S416).} This WCN counter i _WCN is defined for each WCN to be monitored.

Next, the control unit 301 determines whether or not the received WCN matches the priority WCN (step S417). If the received WCN matches the priority WCN (YES in step S417), the first release timer is transmitted to the on-board unit 200 (step S418), and if the received WCN does not match the priority WCN (YES). NO) in step S417, the second release timer is transmitted to the vehicle-mounted device 200 (step S419). Here, the first release timer is a release timer shorter than the second release timer. Since the relationship between the first release timer RT ₁ and the second release timer RT _{2 in} the present embodiment is the same as that described in the first embodiment, the description thereof will be omitted. After transmitting the release timer (that is, the first release timer or the second release timer), the control unit 301 returns the process to step S101, and executes the process after the transmission of the FCMC again.

On the other hand, when the monitoring period is in progress, that is, when the reception of the WCN to be monitored is monitored (YES in step S110), the control unit 301 sets the received WCN as the monitoring target stored in the memory 306. It is determined whether or not it is included (step SS420). If the received WCN is not the monitoring target (NO in step S420), the control unit 301 shifts the process to step S414 and stores the received WCN as a new monitoring target in the memory 306 (step S414). .. After that, in the same manner as described above, the control unit 301 executes the processes of steps S415 to S419.

When the received WCN is the monitoring target (YES in step S420), the control unit 301 of the roadside machine 300 _{increments the value of the WCN counter i WCN} defined for this WCN by one (step S421). It is determined whether or not the value of the WCN counter i _WCN matches the specified number of receptions N (step S422). When the value of the WCN counter i _WCN does not match the specified number of receptions N (NO in step S422), the control unit 301 shifts the process to step S417 and determines whether or not the received WCN matches the priority WCN. (Step S417), the first or second release timer is transmitted according to the determination result (steps S418 and S419).

On the other hand, when _{the value of the WCN counter i WCN} matches the specified number of receptions N (YES in step S422), the control unit 301 determines the received WCN as the target of the authentication process (step S121), and the priority WCN. Is reset (step S423). This removes the WCN from the preferred WCN. The priority WCN reset is the same as that described in the second embodiment.

After step S423, the control unit 301 executes the authentication process (step S123). Since the authentication process is the same as that described in the first embodiment, the description thereof will be omitted. After the authentication process, the control unit 301 shifts the process to step S418, transmits the first release timer to the vehicle-mounted device 200 (step S418), and returns the process to step S101. The above is the communication processing of the roadside machine 300 according to the present embodiment. After that, the FCMC will be transmitted from the roadside unit 300, but since it is not necessary to receive the WCN from the on-board unit 200 that has already been determined as the target of the authentication process, for example, the release timer may be set longer. By ignoring the WCN even if it is received, the above-mentioned communication process is not newly performed between the on-board unit 200 and the roadside unit 300 that have already been determined as the target of the authentication process. To.

Next, the operation of the on-board unit communication system 100 according to the present embodiment will be described with reference to the example shown in FIG. FIG. 17 is a sequence diagram showing an operation flow of the on-board unit communication system 100 in the example shown in FIG. In this example, the monitoring period WT is 600 milliseconds, the first release timer RT ₁ is 200 milliseconds, the second release timer RT ₂ is 400 milliseconds, and the specified number of receptions N is 3.

As shown in FIG. 10, it is assumed that the two vehicles 210a and 210b are in the wireless communication area 350 of the roadside unit 300. First, the on-board unit 200a mounted on the vehicle 210a receives the FCMC transmitted from the roadside unit 300, and the roadside unit 300 receives the ACTC transmitted from the on-board unit 200a accordingly (steps S101a to S104a). After the BST and VST are transmitted and received, the roadside unit 300 makes the first WCN request, and the on-board unit 200a receives this and transmits the first WCN1 (steps S105a to 108a). When the roadside machine 300 receives the first WCN1 (step S109a), the monitoring period WT is not set at this point, so the roadside machine 300 sets the monitoring period WT (step S411) and gives priority to WCN1 as well as WCN1. Set to be monitored.

At this point, the preferred WCN is WCN1, and the received WCN1 and the preferred WCN match. Therefore, the roadside machine 300 _{transmits the first release timer RT 1} , and the vehicle-mounted device 200a receives the first release timer RT ₁ to set the first release timer RT 1 (steps S418a, S115a, S116a).

After transmitting the first release timer RT ₁ , the roadside unit 300 periodically transmits the FCMC again, but since the first release timer RT ₁ is set in the on-board unit 200a, the on-board unit 200a responds to the FCMC. There is nothing to do. However, the release timer is not set in the on-board unit 200b, and the on-board unit 200b responds to the FCMC transmitted from the roadside unit 300. As a result, the on-board unit 200b transmits WCN2, which is its own WCN (steps S101b to S108b).

When the roadside machine 300 receives the WCN2 (step S109b), it is determined whether or not the WCN2 is the monitoring target because the monitoring period WT is in progress. Since the monitoring target set at this point is only WCN1, WCN2 is set as a new monitoring target. That is, the monitoring targets are WCN1 and WCN2. Here, in the present embodiment, the WCN counters i _WCN1 and i _WCN2 are defined for each of WCN1 and WCN2, respectively, and are not reset. In addition, the monitoring period WT is not reset.

The roadside machine 300 determines whether or not the WCN2 and the priority WCN match. Here, since the priority WCN is WCN1, they do not match. Therefore, the roadside machine 300 _{transmits the second release timer RT 2} to the vehicle-mounted device 200b, and the vehicle-mounted device 200b receives the second release timer RT ₂ to set the second release timer RT 2 (steps S419b, S115b, S116b).

After the roadside machine 300 _{transmits the second release timer RT 2} , the FCMC is periodically transmitted again, but since the second release timer RT ₂ is set in the on-board unit 200b, the on-board unit 200b responds to the FCMC. There is nothing to do. _{After that, the first release timer RT 1} of the on-board unit 200a, which is set earlier and _{is shorter than the second release timer RT 2} , ends, and FCMC, ACTC transmission / reception, WCN request, and WCN 1 transmission / reception are performed again ( Steps S101c to S109c). At this point, since the monitoring period WT is in progress, the roadside machine 300 determines whether or not WCN1 is the monitoring target. As described above, since the monitoring targets are WCN1 and WCN2, _{the value of the WCN counter i WCN1} becomes “2”, which matches the number of transmissions of WCN1 of the on-board unit 200a.

The roadside machine 300 determines whether or not the WCN1 and the priority WCN match. The preferred WCN is WCN1 and they are in agreement. Therefore, the roadside unit 300 _{transmits the first release timer RT 1} to the vehicle-mounted device 200a, and the vehicle-mounted device 200a receives the first release timer RT ₁ to set the first release timer RT 1 (steps S418c, S115c, S116c).

After transmitting the first release timer RT ₁ , the roadside unit 300 periodically transmits the FCMC again, but since the first release timer RT ₁ is set in the on-board unit 200a, the on-board unit 200a responds to the FCMC. There is nothing to do. Here, the first release timer RT ₁ ends first, and the second release timer RT ₂ longer than this does not end. Therefore, FCMC, ACTC transmission / reception, WCN request, and WCN1 transmission / reception are performed again between the roadside unit 300 and the on-board unit 200a (steps S101d to S109d). At this point, since the monitoring period WT is in progress, the roadside machine 300 determines whether or not WCN1 is the monitoring target. As described above, since the monitoring targets are WCN1 and WCN2, _{the value of the WCN counter i WCN1} becomes "3", which matches the specified number of receptions N. Therefore, the roadside machine 300 determines WCN1 as the target of the authentication process (step S121) and executes the authentication process (step S123).

By the structure described above, the vehicle 210a, 210b is when entering the radio communication area 350 of the roadside device 300 sets a shorter first release timer RT ₁ is for one of the vehicle-mounted device 200a, other OBE are setting the long second release timer RT ₂ for 200b, erroneous communication with the vehicle-mounted device 200b of the second release timer RT ₂ is set to prevent the provisions receive WCN1 of the vehicle-mounted device 200a It can be received more than the number of times, and the on-board unit 200a can be determined as the target of the authentication process.

(Other embodiments)
In the above-described first to fourth embodiments, the configuration in which the WCN is used as the identification information for identifying the vehicle-mounted device 200 has been described, but the present invention is not limited thereto. For example, LID (Link Address), device number, on-board unit ID, and other identification information can be used.

Further, in the above-described first to fourth embodiments, the roadside units 300 and 330 transmit the release timer to the vehicle-mounted device 200, and the vehicle-mounted device 200 sets the release timer so that the roadside unit 300 can communicate between them. It is configured so that it does not respond so that the on-board unit 200 does not transmit the WCN for a certain period of time, but the present invention is not limited to this. A period other than the release timer may be set as a non-use period during which the reception of WCN is not used for determining the target of the authentication process. Specifically, even if the roadside units 300 and 330 receive the WCN from the on-board unit 200, a non-inclusion period is set in which the WCN is not included in the number of receptions for determining the target of the authentication process, or from the on-board unit 200. Even if the WCN is received, an invalid period for invalidating the reception can be set. It is also possible to set the number of times the WCN is received, which is not used for determining the target of the authentication process, instead of the non-usable period during which the reception of the WCN is not used for determining the target of the authentication process.

The roadside unit, the on-board unit, the on-board unit communication system, the on-board unit communication method, and the computer program of the present invention are the roadside unit that wirelessly communicates with the on-board unit mounted on the vehicle, and the on-board unit and the on-board unit that wirelessly communicate with the roadside unit. It is useful as an on-board unit communication system in which the roadside unit and the roadside unit perform wireless communication, an on-board unit communication method, and a computer program for causing the roadside unit to communicate with the on-board unit.

100 On-board unit communication system 200 On-board unit 201 Control unit 202 Antenna 203 Wireless communication unit 204 Card reader 210 Vehicle 300, 330 Roadside unit 301 Control unit 302 Antenna 303 Wireless communication unit 304 Wired communication unit 305 On-board unit communication program 306 Memory 307 Detection Department 350 Wireless communication area 400 Vehicle management database 500 Entrance / exit gate 501 Pole 600 Communication network

Claims (13)

An antenna that forms a wireless communication area by radiating radio waves,
A request signal requesting identification information for identifying the vehicle-mounted device is transmitted from the vehicle-mounted device to the vehicle-mounted device mounted on the vehicle entering the wireless communication area through the antenna, and the identification information is transmitted from the vehicle-mounted device through the antenna. The receiving wireless communication unit and
When the same identification information is received a plurality of times by the wireless communication unit, the vehicle-mounted device that has transmitted the identification information is determined as a target of information communication processing, and the information regarding the vehicle-mounted device determined as the target. Equipped with a control unit that executes communication processing
The control unit sets a monitoring period for monitoring the reception of the identification information after the identification information is once received from the vehicle-mounted device by the wireless communication unit, and the identification information is the same as the identification information during the monitoring period. As a result of receiving the above-mentioned identification information, when the identification information is received a plurality of times, the on-board unit is determined as the target.
After the identification information is received by the wireless communication unit, the control unit sets a non-use period in which the reception of the identification information is not used for determining the target within the monitoring period.
The monitoring period is longer than the period obtained by multiplying the impossible period by a number smaller than the plurality of times.
Roadside machine. The impossibility period is the release timer.
The control unit is set by transmitting the release timer to the vehicle-mounted device by the wireless communication unit.
The roadside machine according to claim 1. An antenna that forms a wireless communication area by radiating radio waves,
A request signal requesting identification information for identifying the vehicle-mounted device is transmitted from the vehicle-mounted device to the vehicle-mounted device mounted on the vehicle entering the wireless communication area through the antenna, and the identification information is transmitted from the vehicle-mounted device through the antenna. The receiving wireless communication unit and
When the same identification information is received a plurality of times by the wireless communication unit, the vehicle-mounted device that has transmitted the identification information is determined as a target of information communication processing, and the information regarding the vehicle-mounted device determined as the target. Equipped with a control unit that executes communication processing
The control unit sets a monitoring period for monitoring the reception of the identification information after the identification information is once received from the vehicle-mounted device by the wireless communication unit, and the identification information is the same as the identification information during the monitoring period. As a result of receiving the above-mentioned identification information, when the identification information is received a plurality of times, the on-board unit is determined as the target.
When the wireless communication unit receives each of the plurality of identification information transmitted from each of the plurality of vehicle-mounted devices, the control unit monitors one identification information in preference to the other identification information.
After the reception of the one identification information is received by the wireless communication unit, a first non-performing period is set in which the reception of the one identification information is not used for determining the target.
After the other identification information is received by the wireless communication unit, a second impossible period longer than the first impossible period is set, in which the reception of the other identification information is not used for determining the target.
Roadside machine. The second impossible period is equal to or longer than the period obtained by multiplying the first impossible period by the plurality of times.
The roadside machine according to claim 3. When the control unit receives one identification information a plurality of times without receiving other identification information different from the one identification information, the control unit determines the vehicle-mounted device that has transmitted the one identification information as the target. do,
The roadside machine according to any one of claims 1 to 4. When the wireless communication unit receives each of the plurality of identification information transmitted from each of the plurality of vehicle-mounted devices, and the control unit receives one identification information a plurality of times before the other identification information. , The in-vehicle device that has transmitted the above-mentioned identification information is determined as the target.
The roadside machine according to any one of claims 1 to 4. The identification information is WCN.
The roadside machine according to any one of claims 1 to 6. The information communication process is an authentication process for collating the registered WCN with the WCN received from the vehicle-mounted device by the wireless communication unit.
The roadside machine according to any one of claims 1 to 7. The roadside machine according to any one of claims 1 to 8.
Equipped with an in-vehicle device,
The on-board unit
When the identification information for identifying the on-board unit is received a plurality of times, the wireless communication unit that performs wireless communication with the roadside unit that determines the on-board unit as the target of information communication processing, and
When the own device enters the wireless communication area of the roadside unit, the wireless communication unit is controlled to generate a plurality of identification information for identifying the own device in response to a request signal transmitted from the roadside unit. Equipped with a control unit that transmits times
On-board unit communication system. When a vehicle enters a wireless communication area formed by a roadside machine provided on the roadside, a request signal for requesting identification information for identifying the on-board unit from the on-board unit mounted on the vehicle is transmitted. The roadside machine sends and
When the roadside unit receives the identification information from the vehicle-mounted device a plurality of times, the vehicle-mounted device that has transmitted the identification information is determined as a target of information communication processing.
The information communication process regarding the vehicle-mounted device determined as the target is executed.
It is an in-vehicle device communication method,
After the roadside unit receives the identification information from the on-board unit once, a monitoring period for monitoring the reception of the identification information is set, and as a result of receiving the same identification information as the identification information during the monitoring period, the result. When the identification information is received a plurality of times, the vehicle-mounted device is determined as the target.
After the roadside machine receives the identification information, a non-use period during which the reception of the identification information is not used for determining the target is set within the monitoring period.
The monitoring period is longer than the period obtained by multiplying the impossible period by a number smaller than the plurality of times.
On-board unit communication method. When a vehicle enters a wireless communication area formed by a roadside machine provided on the roadside, a request signal for requesting identification information for identifying the on-board unit from the on-board unit mounted on the vehicle is transmitted. The roadside machine sends and
When the roadside unit receives the identification information from the vehicle-mounted device a plurality of times, the vehicle-mounted device that has transmitted the identification information is determined as a target of information communication processing.
The information communication process regarding the vehicle-mounted device determined as the target is executed.
It is an in-vehicle device communication method,
After the roadside unit receives the identification information from the on-board unit once, a monitoring period for monitoring the reception of the identification information is set, and as a result of receiving the same identification information as the identification information during the monitoring period, the result. When the identification information is received a plurality of times, the vehicle-mounted device is determined as the target.
When the roadside unit receives each of the plurality of identification information transmitted from each of the plurality of on-board units, one identification information is monitored in preference to the other identification information.
After receiving the one identification information, a first non-performing period is set in which the reception of the one identification information is not used for determining the target.
After receiving the other identification information, a second impossibility period longer than the first impossibility period is set so that the reception of the other identification information is not used for determining the target.
On-board unit communication method. When a vehicle enters a wireless communication area formed by a roadside unit provided on the roadside, a request signal for requesting identification information for identifying the on-board unit is transmitted to the on-board unit mounted on the vehicle. Transmission means,
When the identification information is received a plurality of times from the vehicle-mounted device, a determination means for determining the vehicle-mounted device that has transmitted the identification information as a target of information communication processing, and the information communication regarding the vehicle-mounted device determined as the target. As an execution means to execute the process
Make your computer work
The determination means sets a monitoring period for monitoring the reception of the identification information after the identification information is once received from the vehicle-mounted device, and the result of receiving the same identification information as the identification information during the monitoring period. When the identification information is received a plurality of times, the vehicle-mounted device is determined as the target.
It said determining means after the front Symbol identification information is received, and set the disabled period is not used in determining the target of the reception of the identification information within the monitoring period,
The monitoring period is longer than the period obtained by multiplying the impossible period by a number smaller than the plurality of times.

Computer program. When a vehicle enters a wireless communication area formed by a roadside unit provided on the roadside, a request signal for requesting identification information for identifying the on-board unit is transmitted to the on-board unit mounted on the vehicle. Transmission means,
When the identification information is received a plurality of times from the vehicle-mounted device, a determination means for determining the vehicle-mounted device that has transmitted the identification information as a target of information communication processing, and the information communication regarding the vehicle-mounted device determined as the target. As an execution means to execute the process
Make your computer work
The determination means sets a monitoring period for monitoring the reception of the identification information after the identification information is once received from the vehicle-mounted device, and the result of receiving the same identification information as the identification information during the monitoring period. When the identification information is received a plurality of times, the vehicle-mounted device is determined as the target.
When each of the plurality of identification information transmitted from each of the plurality of vehicle-mounted devices is received, the determination means monitors one identification information in preference to the other identification information.
After the reception of the one identification information is received, a first non-performing period is set in which the reception of the one identification information is not used for determining the target.
After the other identification information is received, a second impossibility period longer than the first impossibility period is set, in which the reception of the other identification information is not used in determining the target.
Computer program.

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