JP2019185263A - Road-side wireless device and communication method for road-side wireless device - Google Patents

Abstract

To reduce a possibility that a communication is performed with an on-vehicle device that is not a communication subject, in an electronic toll collection system.SOLUTION: A calculation unit 142 of a road-side wireless device 10 in an electronic toll collection system calculates an arrival angle of a radio wave received from an on-vehicle device. A discrimination unit 143 discriminates whether the arrival angle calculated by the calculation unit 142 is an angle indicating the inside of a communication area. In a case where it is discriminated by the discrimination unit 143 that the arrival angle is an angle indicating the inside of the communication area, a communication unit 12 communicates with the on-vehicle device.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a communication technique between a roadside apparatus and an in-vehicle device in an electronic toll collection system.

Roadside radio equipment is installed on the toll booth and highway as equipment for the electronic toll collection system.
The roadside apparatus performs DSRC (Dedicated Short Range Communications) communication with an in-vehicle device mounted on the vehicle, and performs billing processing and the like. When the roadside wireless device forms a communication area on the road and the received power intensity value (RSSI) of the radio wave received from the vehicle-mounted device exceeds the threshold, the roadside device determines that the vehicle has entered the communication area and performs DSRC communication. Do.

JP 2011-23910 A

Since the conventional roadside wireless device is an outdoor communication facility, a radio wave transmitted from the vehicle-mounted device is reflected by an object such as a structure or a vehicle, and multipath waves are generated. And the conventional roadside radio | wireless apparatus may communicate with the onboard equipment which is not communication object under the influence of a multipath wave, and may charge in error. In order to reduce this phenomenon, 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 a vehicle-mounted device that is not a communication target.

The roadside apparatus according to the present invention is:
A roadside wireless device in an electronic toll collection system,
A calculation unit for calculating the angle of arrival of radio waves received from the vehicle-mounted device;
A determination unit that determines whether the angle of arrival calculated by the calculation unit is an angle indicating the inside of a communication area;
And a communication unit that communicates with the vehicle-mounted device when the determination unit determines that the arrival angle is an angle indicating the inside of the communication area.

  In this 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. Thereby, possibility that communication with the vehicle equipment which is not communication object will be performed can be made low.

1 is a configuration diagram of a roadside apparatus 10 according to a first embodiment. FIG. 3 is a flowchart showing the operation of the roadside apparatus 10 according to the first embodiment. Explanatory drawing of operation | movement of the roadside apparatus 10 which concerns on Embodiment 1. FIG. FIG. 3 is a configuration diagram of the angle measuring antenna 13 according to Embodiment 1. Explanatory drawing of the calculation method of the arrival angle which concerns on Embodiment 1. FIG.

Embodiment 1 FIG.
*** Explanation of configuration ***
With reference to FIG. 1, the structure of the roadside apparatus 10 which concerns on Embodiment 1 is demonstrated.
The roadside apparatus 10 is a facility of an electronic toll collection system installed on a toll booth or an expressway.

  The roadside apparatus 10 includes a main antenna 11, a communication unit 12, an angle measurement antenna 13, and an angle measurement calculation unit 14. The communication unit 12 includes a main transmission unit 121, a main reception unit 122, and a shared 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 measurement calculation unit 14 are realized by software or hardware.
When the function is realized by software, the roadside apparatus 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, a program for realizing the function is stored in the memory, and the program is read and executed by the processor. Thereby, a function is realized.
When the function is realized by hardware, the roadside apparatus 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 ***
With reference to FIG.2 and FIG.3, operation | movement of the roadside apparatus 10 which concerns on Embodiment 1 is demonstrated.
The operation of the roadside apparatus 10 according to the first embodiment corresponds to the communication method of the roadside apparatus 10 according to the first embodiment. The operation of the roadside apparatus 10 according to the first embodiment corresponds to the processing of the communication program of the roadside apparatus 10 according to the first embodiment.

(Step S11: Prior communication process)
The main transmission unit 121 of the communication unit 12 transmits a signal called FCMC (Frame Control Message Channel) at regular intervals to the vehicle-mounted device 20 mounted on the vehicle via the common unit 123 and the main antenna 11.
When the in-vehicle device 20 receives the FCMC, the on-vehicle device 20 transmits a signal called ACTC (ACTIVation Channel) to the roadside apparatus 10. Then, the main receiver 122 of the communication unit 12 receives the ACTC via the main antenna 11 and the shared unit 123. Further, the angle measurement reception unit 141 of the angle measurement calculation unit 14 receives the ACTC via the angle measurement antenna 13.

(Step S12: LID extraction process)
The calculation unit 142 of the angle measurement calculation unit 14 extracts LID (vehicle equipment specific information) from the ACTC received by the angle measurement reception unit 141 in step S11. In addition, 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 processing)
The calculation unit 142 of the angle measurement calculation 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 proceeds to step S14. On the other hand, if they do not match, the calculation unit 142 sets the tracking count to 0 and returns the process to step S11.

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

(Step S15: Arrival angle determination process)
The determination unit 143 of the angle measurement calculation unit 14 determines whether or not the arrival angle calculated in step S14 is an angle indicating the communication area. Specifically, as illustrated 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 communication area 30 set in advance. judge. The communication area 30 is set as a partial area in the lane between white lines.

If the angle of arrival is not an angle indicating 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 communication area, the determination unit 143 adds 1 to the number of tracking and determines whether the number of tracking is equal to the reference number. When the tracking number is equal to the reference number, the determination unit 143 advances the process to step S17. On the other hand, when the tracking number is not equal to the reference number, the determination unit 143 returns the process to step S11.

(Step S16: BST discarding process)
The determination unit 143 of the angle measurement calculation unit 14 transmits NGLID information to a control device that performs charge calculation and the like, and discards BST (Beacon Service Table) allocation. And the determination part 143 returns a process to step S11, after setting 0 to the frequency | count of tracking.

(Step S17: Communication processing)
The main transmission unit 121 of the communication unit 12 transmits service information provided by the roadside apparatus 10 called BST to the vehicle-mounted device 20. When receiving the BST, the vehicle-mounted device 20 transmits initial setting information of a mobile station called a VST (Vehicle Service Table) to the roadside apparatus 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 that indicates the arrival angle of each radio wave within the communication region 30. It is determined whether or not. The communication unit 12 communicates with the vehicle-mounted device 20 when it is determined that all the arrival angles for the radio waves received from the vehicle-mounted device 20 for the reference number of times are angles that indicate the inside of the communication region 30.

With reference to FIG.4 and FIG.5, the calculation method of the arrival angle of the electromagnetic wave in step S14 of FIG. 2 is demonstrated.
As shown in FIG. 4, in the first embodiment, the angle measuring antenna 13 is an array antenna in which a total of 64 elements are arranged in 8 elements vertically and horizontally. The angle measuring antenna 13 receives radio waves by each of the 64 elements. The calculation unit 142 calculates the arrival angle of radio waves using an ESPRIT (Estimation of Signal Parameters via Rotational Invariance Techniques) method.
As a specific example, as shown in FIG. 4, the calculation unit 142 uses four elements arranged in two in the vertical and horizontal directions out of 64 elements. The calculation unit 142 handles the four elements as subarray # 1 and subarray # 2 in which two elements are arranged vertically, and as subarray # 3 and subarray # 4 in which two elements are arranged horizontally. The calculation unit 142 calculates the arrival angle in the horizontal direction by the ESPRIT method using the subarray # 1 and the subarray # 2. Further, the calculation unit 142 calculates the arrival angle in the vertical direction by the ESPRIT method using the subarray # 3 and the subarray # 4. Thereby, the arrival angle of a horizontal direction and a vertical direction is specified, and the position of the vehicle carrying the onboard equipment 20 can be specified.

With reference to FIG. 5, the method of calculating the angle of arrival when subarray # 1 and subarray # 2 are taken as an example will be described. Assume that the distance between the elements is 2d. At this time, it is assumed that two radio waves, that is, the radio wave X having the arrival angle θ _{1 and} the radio wave Y having the arrival angle θ ₂ are received. Then, for radio wave X, there is a propagation path distance difference of 2d · sin θ ₁ between subarray # 1 and subarray # 2, and from this distance difference, there is a phase difference between subarray # 1 and subarray # 2. Φ ₁ = exp (j2π · (2d · sin θ ₁ ) / λ). Similarly, for radio wave Y, there is a propagation path distance difference of 2d · sin θ ₂ between sub-array # 1 and sub-array # 2, and from this distance difference between sub-array # 1 and sub-array # 2. There is a phase difference Φ ₂ = exp (j2π · (2d · sin θ ₂ ) / λ).
As shown in Equation 1, a matrix Φ is defined. Further, the matrix indicating the radio wave amplitude and phase received by subarray # 1 and A _1, and A ₂ matrix indicating a radio wave amplitude and phase received by the sub-array # 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 sub-array # 3 and sub-array # 4 are used.

*** Effects of Embodiment 1 ***
As described above, the roadside apparatus 10 according to Embodiment 1 performs communication 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 region 30. Thereby, it can reduce that communication with the onboard equipment 20 which is not communication object is performed.
That is, the roadside apparatus 10 according to the first embodiment communicates only with the vehicle-mounted device 20 to be communicated even in an environment where multipath may occur by grasping the position of the vehicle. It becomes possible.

*** Other configurations ***
<Modification 1>
In the first embodiment, whether or not to perform communication is determined based only on the arrival angle of radio waves. However, whether to perform communication may be determined in consideration of whether the received power intensity value of the radio wave received from the vehicle-mounted device is higher than a 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 a threshold value. When the communication unit 12 determines that the reception strength is higher than the threshold and the arrival angles for the radio waves received from the vehicle-mounted device 20 for the reference number of times are all angles indicating the communication area 30, Communication with the vehicle-mounted device 20 is performed.

  DESCRIPTION OF SYMBOLS 10 Roadside apparatus, 11 main antenna, 12 communication part, 121 main transmission part, 122 main reception part, 123 common use part, 13 angle measurement antenna, 14 angle measurement calculation part, 141 angle measurement reception part, 142 calculation part, 143 determination Part, 20 vehicle-mounted device, 30 communication area.

Claims (5)

A roadside wireless device in an electronic toll collection system,
A calculation unit for calculating the angle of arrival of radio waves received from the vehicle-mounted device;
A determination unit that determines whether the angle of arrival calculated by the calculation unit is an angle indicating the inside of a communication area;
A roadside radio apparatus comprising: a communication unit that communicates with the vehicle-mounted device when the determination unit determines that the arrival angle is an angle indicating the inside of the communication area. The calculation unit calculates the arrival angle of each radio wave repeatedly received from the on-vehicle device,
The determination unit determines whether the arrival angle is an angle indicating the inside of the communication area for each radio wave,
The communication unit performs communication with the vehicle-mounted device when it is determined that the arrival angle of the radio wave received from the vehicle-mounted device for a reference number of times is an angle indicating the inside of the communication area. The roadside radio device according to the above. The determination unit determines whether the reception intensity of the radio wave is higher than a threshold value,
2. The communication unit according to claim 1, wherein the communication unit performs communication with the vehicle-mounted device when it is determined that the reception intensity is higher than the threshold and the angle of arrival is an angle indicating the inside of the communication area. Roadside radio device. The roadside apparatus receives the radio wave by a plurality of elements constituting an array antenna,
The roadside wireless device according to any one of claims 1 to 3, wherein the calculation unit calculates the angle of arrival from a phase difference between the radio waves received by the plurality of elements. A communication method for a roadside wireless device in an electronic toll collection system,
Calculate the arrival angle of the radio wave received from the OBE,
It is determined whether the calculated arrival angle is an angle indicating the communication area,
A communication method of a roadside apparatus that performs communication with the vehicle-mounted device when it is determined that the angle of arrival is an angle indicating the inside of the communication area.

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