JP6991096B2 - Communication method of roadside wireless device and roadside wireless device - Google Patents

Description

The present invention relates to a communication technique between a roadside wireless device and an on-board unit in an electronic toll collection system.

Roadside wireless devices will be installed on tollhouses and highways as equipment for electronic toll collection systems.
The roadside wireless device performs DSRC (Dedicated Short Range Communications) communication with the on-board unit mounted on the vehicle, and performs billing processing and the like. The roadside radio device forms a communication area on the road, and when the received power intensity value (RSSI) of the radio wave received from the on-board unit exceeds the threshold value, it determines that the vehicle has entered the communication area and performs DSRC communication. conduct.

Japanese Unexamined Patent Publication No. 2011-23910

Since the conventional roadside radio device is an outdoor communication facility, the radio wave transmitted from the on-board unit is reflected by an object such as a structure or a vehicle to generate a multipath wave. Then, the conventional roadside wireless device may communicate with an in-vehicle device that is not a communication target due to the influence of the multipath wave, resulting in erroneous charging. In order to mitigate this event, this event may occur even in a place where a radio wave absorption band is installed and operated so that reflection can be reduced.
An object of the present invention is to reduce the possibility of communication with an in-vehicle device that is not a communication target.

The roadside wireless device according to the present invention is
It is a roadside wireless device in the electronic toll collection system.
A calculation unit that calculates the arrival angle of radio waves received from the in-vehicle device,
A determination unit for determining whether or not the arrival angle calculated by the calculation unit is an angle indicating the inside of the communication area, and a determination unit.
When the determination unit determines that the arrival angle is an angle indicating the inside of the communication area, the determination unit includes a communication unit that communicates with the vehicle-mounted device.

In the present invention, when the arrival angle of the radio wave received from the vehicle-mounted device is an angle indicating the inside of the communication area, communication with the vehicle-mounted device is performed. As a result, it is possible to reduce the possibility of communication with the in-vehicle device that is not the communication target.

The block diagram of the roadside wireless apparatus 10 which concerns on Embodiment 1. FIG. The flow diagram which shows the operation of the roadside wireless apparatus 10 which concerns on Embodiment 1. FIG. An explanatory diagram of the operation of the roadside wireless device 10 according to the first embodiment. The block diagram of the angle measuring antenna 13 which concerns on Embodiment 1. FIG. The explanatory view of the calculation method of the arrival angle which concerns on Embodiment 1.

Embodiment 1.
*** Explanation of configuration ***
The configuration of the roadside wireless device 10 according to the first embodiment will be described with reference to FIG. 1.
The roadside radio device 10 is a facility of an electronic toll collection system installed on a tollhouse or a highway.

The roadside wireless device 10 includes a main antenna 11, a communication unit 12, an angle measuring antenna 13, and an angle measuring unit 14. The communication unit 12 includes a main transmission unit 121, a main reception unit 122, and a common unit 123. The angle measurement calculation unit 14 includes an angle measurement reception unit 141, a calculation unit 142, and a determination unit 143.

The functions of the communication unit 12 and the angle calculation unit 14 are realized by software or hardware.
If the function is realized by software, the roadside radio device 10 includes a processor and a memory. The processor is an IC (Integrated Circuit) that performs processing, and a CPU (Central Processing Unit) is assumed. The memory is assumed to be a ROM (Read Only Memory) or a memory card. Then, the program for realizing the function is stored in the memory, and the program is read and executed by the processor. As a result, the function is realized.
When the function is realized by hardware, the roadside radio device 10 includes an electronic circuit for realizing the function. The electronic circuit may be a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, a logic IC, a GA (Gate Array), an ASIC (Application Specific Integrated Circuit), or an FPGA (Field-Programmable Gate Array). is assumed.

*** Explanation of operation ***
The operation of the roadside wireless device 10 according to the first embodiment will be described with reference to FIGS. 2 and 3.
The operation of the roadside wireless device 10 according to the first embodiment corresponds to the communication method of the roadside wireless device 10 according to the first embodiment. Further, the operation of the roadside wireless device 10 according to the first embodiment corresponds to the processing of the communication program of the roadside wireless device 10 according to the first embodiment.

(Step S11: Pre-communication processing)
The main transmission unit 121 of the communication unit 12 transmits a signal called FCMC (Frame Control Message Channel) to the vehicle-mounted device 20 mounted on the vehicle via the common unit 123 and the main antenna 11.
When the vehicle-mounted device 20 receives the FCMC, it transmits a signal called ACTC (ACTVation Channel) to the roadside wireless device 10. Then, the main receiving unit 122 of the communication unit 12 receives the ACTC via the main antenna 11 and the common unit 123. Further, the angle measuring receiving unit 141 of the angle measuring unit 14 receives the ACTC via the angle measuring antenna 13.

(Step S12: LID extraction process)
The calculation unit 142 of the angle measurement unit 14 extracts LID (on-board unit unique information) from the ACTC received by the angle measurement reception unit 141 in step S11. Further, the calculation unit 142 acquires the LID extracted from the ACTC received by the main reception unit 122 in step S11.

(Step S13: LID determination process)
The calculation unit 142 of the angle measurement unit 14 is extracted from the LID extracted from the ACTC received by the angle measurement reception unit 141 in step S12 and the ACTC received by the main reception unit 122 acquired in step S12. It is determined whether or not the LID matches.
If they match, the calculation unit 142 advances the process to step S14. On the other hand, if they do not match, the calculation unit 142 sets the number of tracking times to 0 and then returns the process to step S11.

(Step S14: Arrival angle calculation process)
The calculation unit 142 of the angle measurement unit 14 calculates the arrival angle of the ACTC radio wave received by the angle measurement reception unit 141 in step S11. The method of calculating the arrival angle of radio waves will be described later.

(Step S15: Arrival angle determination process)
The determination unit 143 of the angle measurement unit 14 determines whether or not the arrival angle calculated in step S14 is an angle indicating the inside of the communication area. Specifically, as shown in FIG. 3, the determination unit 143 determines whether or not the horizontal plane angle and the vertical plane angle of the arrival angle of the radio wave are angles indicating the range of the preset communication region 30. judge. As the communication area 30, a part of the area in the lane sandwiched between the white lines and the like is set.

If the arrival angle is not an angle indicating the inside of the communication area, the determination unit 143 of the angle measurement calculation unit 14 advances the process to step S16.
On the other hand, when the arrival angle is an angle indicating the inside of the communication area, the determination unit 143 determines whether or not the number of tracking times is equal to the reference number of times after adding 1 to the number of tracking times. If the number of trackings is equal to the reference number, the determination unit 143 advances the process to step S17. On the other hand, if the number of trackings is not equal to the reference number, the determination unit 143 returns the process to step S11.

(Step S16: BST discard process)
The determination unit 143 of the angle measurement unit 14 transmits the NGLID information to the control device that performs charge calculation and the like, and causes the BST (Beacon Service Table) allocation to be discarded. Then, the determination unit 143 sets the number of tracking times to 0 and then returns the process to step S11.

(Step S17: Communication processing)
The main transmission unit 121 of the communication unit 12 transmits the service information provided by the roadside wireless device 10 called BST to the vehicle-mounted device 20. When the vehicle-mounted device 20 receives the BST, it transmits the initial setting information of the mobile station called VST (Vehicle Service Table) to the roadside wireless device 10.

That is, as shown in FIG. 3, the calculation unit 142 calculates the arrival angle of each radio wave repeatedly received from the vehicle-mounted device 20, and the determination unit 143 is an angle indicating that the arrival angle of each radio wave is within the communication area 30. Judge whether or not. Then, the communication unit 12 communicates with the vehicle-mounted device 20 when it is determined that the arrival angles of the radio waves received from the vehicle-mounted device 20 continuously for the reference number of times are all angles indicating the inside of the communication area 30.

A method of calculating the arrival angle of the radio wave in step S14 of FIG. 2 will be described with reference to FIGS. 4 and 5.
As shown in FIG. 4, in the first embodiment, the angle measuring antenna 13 is an array antenna in which eight elements are arranged vertically and horizontally, for a total of 64 elements. The angle measuring antenna 13 receives radio waves by each of the 64 elements. The calculation unit 142 calculates the arrival angle of the radio wave by using the ESPRIT (Estimation of Signal Parameters via Rotational Investment Technologies) method.
As a specific example, as shown in FIG. 4, the calculation unit 142 uses four elements in which two elements are arranged vertically and horizontally among the 64 elements. The calculation unit 142 treats the four elements as sub-array # 1 and sub-array # 2 in which two elements are arranged vertically, and as sub-array # 3 and sub-array # 4 in which two elements are arranged horizontally. The calculation unit 142 calculates the horizontal arrival angle by the ESPRIT method using the sub-array # 1 and the sub-array # 2. Further, the calculation unit 142 calculates the arrival angle in the vertical direction by the ESPRIT method using the sub-array # 3 and the sub-array # 4. Thereby, the arrival angles in the horizontal direction and the vertical direction can be specified, and the position of the vehicle on which the on-board unit 20 is mounted can be specified.

With reference to FIG. 5, a method of calculating the arrival angle when the sub-array # 1 and the sub-array # 2 are taken as an example will be described. It is assumed that the distance between the elements is 2d. At this time, it is assumed that two radio waves, a radio wave X having an arrival angle θ ₁ and a radio wave Y having an arrival angle θ ₂ , are received. Then, regarding the radio wave X, there is a distance difference of the propagation path between the sub array # 1 and the sub array # 2 by 2d · sin θ ₁ , and the phase difference between the sub array # 1 and the sub array # 2 is due to this distance difference. There is Φ ₁ = exp (j2π · (2d · sinθ ₁ ) / λ). Similarly, regarding the radio wave Y, there is a distance difference in the propagation path between the sub array # 1 and the sub array # 2 by 2d · sinθ ₂ , and from this distance difference, there is a distance difference between the sub array # 1 and the sub array # 2. There is a phase difference Φ ₂ = exp (j2π · (2d · sinθ ₂ ) / λ).
The matrix Φ is defined as shown in Equation 1. Further, the matrix showing the amplitude and phase of the radio wave received in the sub array # 1 is referred to as A ₁ , and the matrix showing the amplitude and phase of the radio wave received in the sub array # 2 is referred to as A ₂ . Then, it can be expressed as A ₁ = A ₂ Φ, and A _{2-1 A 1} ⁼ Φ. The arrival angles θ ₁ and θ ₂ can be calculated from this equation.

The arrival angle can be calculated in the same manner when the sub array # 3 and the sub array # 4 are used.

*** Effect of Embodiment 1 ***
As described above, the roadside wireless device 10 according to the first embodiment communicates with the vehicle-mounted device 20 when the arrival angle of the radio wave received from the vehicle-mounted device 20 is an angle indicating the inside of the communication area 30. As a result, it is possible to reduce communication with the vehicle-mounted device 20 that is not the communication target.
That is, the roadside wireless device 10 according to the first embodiment communicates only with the vehicle-mounted device 20 to be communicated by grasping the position of the vehicle even in an environment where multipath may occur. Will be possible.

*** Other configurations ***
<Modification 1>
In the first embodiment, it is determined whether or not communication is performed based only on the arrival angle of the radio wave. However, it may be determined whether or not communication is performed in consideration of whether or not the received power intensity value of the radio wave received from the vehicle-mounted device is higher than the threshold value.
That is, the determination unit 143 determines whether or not the reception intensity of the radio wave received by the main reception unit 122 in step S11 is higher than the threshold value. Then, when the communication unit 12 determines that the reception intensity is higher than the threshold value and the arrival angles of the radio waves received from the vehicle-mounted device 20 continuously for the reference number of times are all angles indicating the inside of the communication area 30. Communicates with the vehicle-mounted device 20.

10 Roadside wireless device, 11 main antenna, 12 communication unit, 121 main transmission unit, 122 main reception unit, 123 common unit, 13 angle measurement antenna, 14 angle measurement calculation unit, 141 measurement reception unit, 142 calculation unit, 143 judgment Department, 20 on-board equipment, 30 communication areas.

Claims (3)

It is a roadside wireless device in the electronic toll collection system.
After transmitting the FCMC (Frame Control Message Channel) signal to the in-vehicle device by the main antenna, the in-vehicle device specific information extracted from the ACTC (ACTivation Channel) radio waves received by each of the main antenna and the angle measuring antenna. 4 are arranged in each of the vertical direction and the horizontal direction constituting the angle measuring antenna, which is an array antenna in which three or more elements are arranged in each of the vertical direction and the horizontal direction. A calculation unit that calculates the arrival angle of the radio wave received by the sub-array consisting of one element from the phase difference between the two elements in each of the vertical direction and the horizontal direction .
A determination unit for determining whether or not the arrival angle of the radio wave calculated by the calculation unit is an angle indicating the inside of the communication area, and a determination unit.
When the determination unit determines that the arrival angle of the radio wave received from the vehicle-mounted device continuously for a reference number of times after transmitting the FCMC is an angle indicating the inside of the communication area, the vehicle-mounted device is determined. BST (Beacon Service Table) is transmitted, and when the determination unit determines that the arrival angle is not an angle indicating the inside of the communication area, the vehicle is provided with a communication unit that does not transmit BST to the on-board unit. Roadside radio device. The determination unit determines whether or not the reception intensity of the radio wave is higher than the threshold value.
The first aspect of the present invention, wherein the communication unit communicates with the vehicle-mounted device when it is determined that the reception strength is higher than the threshold value and the arrival angle is an angle indicating the inside of the communication region. Roadside radio device. It is a communication method of roadside wireless devices in the electronic toll collection system.
After transmitting the FCMC (Frame Control Message Channel) signal to the in-vehicle device by the main antenna, the in-vehicle device specific information extracted from the ACTC (ACTivation Channel) radio waves received by each of the main antenna and the angle measuring antenna. 4 are arranged in each of the vertical direction and the horizontal direction constituting the angle measuring antenna, which is an array antenna in which three or more elements are arranged in each of the vertical direction and the horizontal direction. For the radio wave received by the sub-array consisting of one element, the arrival angle is calculated from the phase difference between the two elements in each of the vertical direction and the horizontal direction .
It is determined whether or not the arrival angle of the calculated radio wave is an angle indicating the inside of the communication area.
When it is determined that the arrival angle of the radio wave received from the vehicle-mounted device consecutively after transmitting the FCMC is an angle indicating the inside of the communication area, BST (Beacon) is determined with respect to the vehicle-mounted device. A communication method of a roadside radio device that does not transmit BST to the on-board unit when it is determined that the arrival angle is not an angle indicating the inside of the communication area by transmitting Service Table).

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