JP2016161282A - Angle detection apparatus, wireless communication system, angle detection method, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an angle detection device with which it is possible to suppress the false recognition of the arrival angle of a radio wave.SOLUTION: An angle detection device 20A comprises: a phase difference detection unit 200 for selecting a plurality of combinations consisting of two antennas among three or more antennas arrayed along a reference line, and detecting a phase difference between incoming waves received by the two antennas pertaining to a combination; a candidate value arithmetic unit 201 for calculating a candidate value for the arrival angle of an incoming wave on the basis of the phase difference and the spacing of the two antennas pertaining to a combination used in detecting the phase difference; and an arrival angle identification unit 202 for identifying the detection value of an arrival angle on the basis of the candidate value calculated for each of the plurality of combinations.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an angle detection device, a wireless communication system, an angle detection method, and a program.

  An electronic toll collection system (ETC (registered trademark)) that automatically establishes wireless communication with a running vehicle at a toll road such as a toll road such as an expressway and performs billing processing by electronic payment Electronic Toll Collection System, also called “automatic toll collection system”). In the electronic toll collection system, when a vehicle traveling in a lane arrives in a predetermined communicable area, a wireless communication device installed on the lane and an in-vehicle device installed in the user's vehicle are automatically The billing process is performed by performing a wireless communication process. In this way, the charging process is performed without hindering the traveling of the vehicle by wireless communication, so that the occurrence of traffic jams can be effectively suppressed.

  In the above-mentioned entrance toll booth or the like, usually, a plurality of traveling lanes are laid in parallel, and the above-described wireless communication devices are also installed corresponding to each of the plurality of traveling lanes. In this case, the wireless communication device corresponding to one travel lane has a communicable area in advance in order to avoid wireless communication (erroneous communication) with the vehicle-mounted device of the vehicle traveling in another travel lane. It is limited within the range of the corresponding traveling lane (own traveling lane).

However, there are various buildings (ceilings, pillars, etc.) that constitute an entrance toll gate and the like around the wireless communication device. Therefore, there is a possibility that the electromagnetic waves radiated from the wireless communication device are reflected by the building or the like and radiated to an area that is not assumed in design. Then, such unexpected reflection may cause erroneous communication with a vehicle traveling in another traveling lane adjacent to the own traveling lane, for example.
In order to solve such problems, measures have been taken to prevent erroneous communication with unintended vehicles by providing a radio wave absorbing material on the surface of the building such as the ceiling to suppress reflection of electromagnetic waves. Yes.

  However, the above-described radio wave absorbing material is not only expensive, but also requires installation and maintenance costs for reliable installation and maintenance in the building.

  On the other hand, in addition to the method using the radio wave absorbing material, by using an array antenna formed by arranging a plurality of antenna elements, the arrival angle of the incoming electromagnetic wave is estimated and the radio wave arrives from the desired arrival angle A technique for performing wireless communication for billing only is disclosed (for example, see Patent Document 1).

Japanese Patent No. 4810730

  In the method of estimating the arrival angle using the array antenna, the arrival angle is mainly estimated based on the phase difference of the arrival waves (electromagnetic waves) received by each of the plurality of antenna elements. However, it is generally known that the phase difference between two electromagnetic waves having the same frequency has an uncertainty of ± 360 ° (2π) × n (n is an integer). That is, even when the phase difference φ between the two electromagnetic waves is detected through a predetermined phase difference detector, the actual phase shift between the two electromagnetic waves is further increased by the n period ( 360 ° × n) It cannot be specified whether or not there is a deviation.

  Therefore, for electromagnetic waves coming from an angle that does not satisfy the predetermined conditions based on the structure of the array antenna (interval between the plurality of antenna elements), the wavelength of the electromagnetic waves, etc., the calculation result (solution) according to the detected phase difference is There are cases where a plurality of electromagnetic waves cannot be uniquely identified. Then, depending on the signal processing method, there is a case where the electromagnetic wave is erroneously recognized as coming from an angle different from the true arrival angle.

  An object of the present invention is to provide an angle detection device, a wireless communication system, an angle detection method, and a program that can suppress erroneous recognition of the arrival angle of an electromagnetic wave.

One aspect of the present invention is to select a plurality of combinations of two antenna elements among three or more antenna elements (10a, 10b, 10c) arranged along a reference line, and to A phase difference detection unit (200) for detecting a phase difference (φ ₁ , φ ₂ ) of an incoming wave (E) received by the antenna element, and the phase difference and the combination used for detecting the phase difference Candidate value calculation unit (θ _{11 to} θ ₁₄ , θ _{21 to} θ ₂₄ ) that calculates the arrival angle candidate values (θ _{11 to} θ ₁₄ , θ _{21 to} θ ₂₄ ) based on the distance (d ₁ , d ₂ ) between the two antenna elements. 201) and an arrival angle specifying unit 202 that specifies the detection value (θd) of the arrival angle based on the candidate values calculated for each of the plurality of combinations.
In this way, even if it is not possible to specify a single arrival angle solution (candidate value) by only one set of antenna elements due to phase difference uncertainty, another set of antennas By referring to the solution obtained from the combination of elements and narrowing down, the accuracy of the solution can be improved. Therefore, even if the incident light is incident from an arrival angle where a single solution cannot be specified in the past, it is possible to accurately detect that the incident light is incident from the arrival angle.

Moreover, according to one aspect of the present invention, the phase difference detection unit according to the angle detection device described above is configured such that an interval between two antenna elements according to one of the combinations is two antennas according to the other combination. A plurality of the combinations that do not become an integral multiple of the element spacing are selected.
By doing so, it is possible to prevent the arrival angle from being uniquely specified by the candidate values calculated for each of the plurality of combinations of antenna elements.

Moreover, according to one aspect of the present invention, the phase difference detection unit according to the angle detection device described above includes two antennas arranged in a plurality of the combinations with one or more antenna elements interposed therebetween. Includes combinations of elements.
By doing so, the difference between the distance between the antenna elements according to the combination of one antenna element and the distance between the antenna elements according to the combination of the other antenna elements can be increased. Can be identified well.

Moreover, according to one aspect of the present invention, the arrival angle specifying unit according to the angle detection device described above includes a plurality of candidate values calculated for one of the plurality of candidate values calculated for one of the combinations. One candidate value common to any one of the candidate values is specified as the detected value.
By doing in this way, since the detection value of an arrival angle can be narrowed down to one candidate value common over the combination of different antenna elements, it has the highest accuracy among a plurality of candidate values with a simple process. One candidate value can be selected as a detection value.

Also, according to one aspect of the present invention, the angle detection device described above is an estimated value of the arrival angle of the incoming wave based on signal processing on the amplitude and phase of the incoming wave received by three or more antenna elements. A signal processing unit (203) for calculating (θs), and the arrival angle specifying unit is configured to determine that the detected value specified based on the candidate value is within an estimable range corresponding to the signal processing. The estimated value calculated based on the signal processing is specified as the detected value.
In this way, if it is expected that electromagnetic waves are coming from a range where the estimated value can be uniquely specified based on the vector calculation (amplitude and phase) of the incoming wave, the signal processing is separately performed. Based on the arrival angle estimation process based on this, an estimated value that is the calculation result is output. Therefore, a more accurate detection result can be obtained.

Moreover, according to one aspect of the present invention, the arrival angle specifying unit according to the angle detection device described above has the detection value (θ [rad]) specified based on a plurality of candidate values of the arrival angle, The estimation that satisfies the condition of | θ | <sin ⁻¹ (λ / 2d) with respect to the wavelength (λ [m]) of the incoming wave and the interval (d [m]) between three or more antenna elements When it is within the range, the estimated value calculated based on the signal processing is specified as the detected value.
By doing in this way, when the phase difference of the incoming wave which can calculate an estimated value uniquely based on signal processing is given in the range of 180 ° to −180 ° (+ π to −π), the condition is satisfied. The arrival angle estimation process based on the signal processing can be performed only when the incoming wave is incident at the arrival angle.

  Another embodiment of the present invention is the above-described angle detection device and three or more antenna elements, and is provided from an in-vehicle device mounted on a vehicle (A1, A2) traveling in a lane (L1, L2). A wireless communication system (1A) comprising an array antenna that receives the incoming wave.

  In one embodiment of the present invention, a plurality of combinations of two antenna elements are selected from three or more antenna elements arranged along a reference line, and reception is performed by the two antenna elements according to the combination. Detecting the phase difference of the incoming waves based on the step of detecting the phase difference of the incoming waves, the phase difference, and the interval between the two antenna elements according to the combination used for detecting the phase difference An angle detection method comprising: calculating a value; and specifying a detection value of the arrival angle based on the candidate value calculated for each of the plurality of combinations.

  According to one embodiment of the present invention, a computer of an angle detection device selects a plurality of combinations including two antenna elements from among three or more antenna elements arranged along a reference line, and relates to the combination. Based on phase difference detection means for detecting a phase difference between incoming waves received by two antenna elements, the phase difference, and an interval between the two antenna elements according to the combination used for detecting the phase difference. , Candidate value calculating means for calculating a candidate value for the arrival angle of the incoming wave, and arrival angle specifying means for specifying the detected value of the arrival angle based on the candidate value calculated for each of the plurality of combinations. It is a program that makes it work.

  According to the above-described angle detection device, wireless communication system, angle detection method, and program, erroneous recognition of the arrival angle of electromagnetic waves can be suppressed.

It is a figure which shows the outline | summary of the radio | wireless communications system which concerns on 1st Embodiment. It is a figure which shows the function structure of the radio | wireless communications system which concerns on 1st Embodiment. It is a figure which shows the structure of the array antenna which concerns on 1st Embodiment. It is the 1st figure explaining the function of the angle detector concerning a 1st embodiment. It is a 2nd figure explaining the function of the angle detection apparatus which concerns on 1st Embodiment. It is a 3rd figure explaining the function of the angle detection apparatus which concerns on 1st Embodiment. It is a 4th figure explaining the function of the angle detection apparatus which concerns on 1st Embodiment. It is a figure which shows the function structure of the radio | wireless communications system which concerns on 2nd Embodiment. It is a figure which shows the processing flow of the angle detection apparatus which concerns on 2nd Embodiment.

<First Embodiment>
Hereinafter, the wireless communication system according to the first embodiment will be described with reference to FIGS.

(overall structure)
FIG. 1 is a diagram illustrating an outline of a wireless communication system according to the first embodiment.
As shown in FIG. 1, a wireless communication system 1A according to the first embodiment is provided in a toll collection facility 1 laid at an entrance toll gate, an exit toll gate, or the like of a highway that is a toll road.
Here, the toll collection facility 1 performs wireless communication processing (wireless communication) with dedicated vehicle-mounted devices mounted on the vehicles A1, A2, etc. traveling on the lanes L1, L2, and performs charging processing by electronic settlement.

As shown in FIG. 1, the toll collection facility 1 includes a wireless communication system 1 </ b> A, an approach side vehicle detector 30, a start control device 40, and a start side vehicle detector 50.
The wireless communication system 1A is a system that performs charging processing through wireless communication with the vehicle-mounted devices mounted on the vehicles A1 and A2. The wireless communication system 1A is provided corresponding to each of the lanes L1 and L2 of the toll collection facility 1.
The approach-side vehicle detector 30 is provided on the road side of the lanes L1 and L2, determines whether or not the vehicles A1 and A2 traveling on the lane L are present, and detects entry and passage of one vehicle A1 and A2. To do.
The start control device 40 performs start control of the vehicles A1 and A2 traveling in the lanes L1 and L2. For example, when the charging process with the vehicle A1 is not properly performed, the start control device 40 closes the lane L1 so as to restrict the exit of the vehicle A1. The start control device 40 opens the lane L1 when the charging process for the vehicle A1 is properly completed.

  The start side vehicle detector 50 detects the exit of the vehicles A1 and A2 from the toll collection facility 1. The start side vehicle detector 50 detects the passing and leaving of the vehicles A1 and A2 by the same mechanism as the approach side vehicle detector 30 described above.

As shown in FIG. 1, the wireless communication system 1 </ b> A includes a wireless communication device 10 and a roadside system 20.
The wireless communication device 10 is attached to the ceiling R built in the toll collection facility 1 and is connected to the vehicles A1 and A2 (on-vehicle devices) that have entered the communicable areas Q1 and Q2 defined in advance on the lanes L1 and L2. Wireless communication for billing processing is performed between them.
The roadside system 20 performs billing processing based on the result of wireless communication between the wireless communication device 10 and the vehicles A1 and A2. In addition, the roadside system 20 manages necessary cooperation operations in the toll collection facility 1 such as detecting that the charging process for the vehicles A1 and A2 has been properly performed and opening the start control device 40, for example.

The wireless communication device 10 according to the present embodiment has an array antenna 10A inside. As will be described later, the array antenna 10A is used to detect the angle of arrival of electromagnetic waves from the vehicle-mounted devices mounted on the vehicles A1 and A2.
Here, in FIG. 1, it is assumed that the wireless communication device 10 provided corresponding to the lane L1 performs wireless communication with the vehicle A1 that has entered the communicable area Q1 defined on the lane L1. Yes. Similarly, it is assumed that the wireless communication device 10 provided corresponding to the lane L2 performs wireless communication with the vehicle A2 that has entered the communicable area Q2 defined on the lane L2.
However, in operation of the toll collection facility 1, unexpected reflection of electromagnetic waves may occur due to the presence of a building such as the ceiling R or other obstacles such as a traveling vehicle. For example, electromagnetic waves radiated from the vehicle-mounted device of the vehicle A2 traveling in the lane L2 may arrive at the wireless communication device 10 provided corresponding to the lane L1 through reflection on the ceiling R or the like. Then, the wireless communication device 10 erroneously recognizes that the incoming electromagnetic wave is emitted from the vehicle A1 traveling on the lane L1, and causes the roadside system 20 to malfunction.

  Therefore, the roadside system 20 according to the present embodiment has a function of detecting the arrival angle of the electromagnetic wave from the vehicle-mounted device through the array antenna 10A described above, and the corresponding lane (lane L1) based on the detected value of the arrival angle. , L2), it is determined whether or not wireless communication with the vehicle (vehicles A1, A2) traveling is performed.

(Functional configuration of wireless communication system)
FIG. 2 is a diagram illustrating a functional configuration of the wireless communication system according to the first embodiment.
FIG. 3 is a diagram showing the structure of the array antenna according to the first embodiment.
As shown in FIG. 2, the wireless communication system 1 </ b> A includes a wireless communication device 10 and a roadside system 20.

  The wireless communication device 10 has the array antenna 10A described above. The roadside system 20 includes an angle detection device 20A that receives an electromagnetic wave (arrival wave) received by the array antenna 10A and detects an arrival angle of the electromagnetic wave.

Here, the structure of the array antenna 10A will be described in detail with reference to FIG.
As shown in FIG. 3, the array antenna 10A includes three antenna elements (first antenna element 10a and second antenna element 10b) along a predetermined reference line (for example, the X-axis direction shown in FIG. 3) on the substrate 11. And the third antenna element 10c).
The distance d ₁ between the first antenna element 10a and the second antenna element 10b is arranged so that d ₁ = 0.6λ. In addition, the distance d ₂ between the first antenna element 10a and the third antenna element 10c is arranged so that d ₂ = 1.3λ.
“Λ” is the wavelength of the electromagnetic wave used for wireless communication with the wireless communication device 10 and the vehicle-mounted device. In this embodiment, electromagnetic waves having a frequency of about 5.8 GHz are used for wireless communication performed between the wireless communication device 10 and the vehicle-mounted device. In this case, the wavelength λ is about 5 cm.

As shown in FIG. 3, each antenna element (first antenna element 10a to third antenna element 10c) receives an incoming wave E that is an electromagnetic wave radiated from the vehicle-mounted device. At this time, the incoming wave E is incident on each antenna element at a predetermined arrival angle θ. Here, the arrival angle θ is an incident angle of the arrival wave E with reference to the normal direction of the plate surface (XY plane) of the substrate 11.
Considering that the distance between the wireless communication device 10 and the vehicles A1 and A2 (onboard equipment) is sufficiently larger than the distances d ₁ and d ₂ , the incoming wave E is generated by the first antenna element 10a and the second antenna. It can be considered that each of the element 10b and the third antenna element 10c is a plane wave that arrives at the same arrival angle θ.

Then, a phase difference φ ₁ is generated in each incoming wave E according to the path difference Δ ₁ between the incoming wave E received by the first antenna element 10 a and the incoming wave E received by the second antenna element 10 b. Therefore, the phase difference φ ₁ can be calculated by the following equation (1) based on the relational expression (Δ ₁ = (λ / 2π) · φ ₁ ) between the path difference Δ ₁ and the phase difference φ _1. .

Similarly, the phase difference phi ₂ between the incoming wave E where the incoming wave E where the first antenna element 10a is received by the third antenna element 10c is received, the path difference delta ₂ and the phase difference phi ₂ and the relational expression (delta ₂ = (Λ / 2π) · φ ₂ ) can be calculated by the following formula (2).

As described above, when the array antenna 10A (the first antenna element 10a, the second antenna element 10b, and the third antenna element 10c) receives the incoming wave E, it has a geometrical shape according to the arrival angle θ of the incoming wave E. Thus, phase differences φ ₁ and φ ₂ (see formulas (1) and (2)) are determined.

In FIG. 3, only three antenna elements (first antenna element 10a, second antenna element 10b, and third antenna element 10c) arranged along one reference line (X-axis direction) on the substrate 11 are shown. In practice, a plurality of antenna elements are similarly arranged along another reference line on the substrate 11 (for example, the Y-axis direction orthogonal to the X-axis direction). The functions and functions of the antenna elements arranged along the other reference lines are the same as those of the first antenna element 10a to the third antenna element 10c described above.
Further, each antenna element (first antenna element 10a to third antenna element 10c) shown in FIG. 3 is merely a schematic representation of the arrangement of each antenna element, and the actual structure of the antenna element is as follows. It may be different from that shown in FIG. For example, each antenna element may be a patch antenna or the like formed on the substrate 11.

  As illustrated in FIG. 2, the angle detection device 20 </ b> A includes a phase difference detection unit 200, a candidate value calculation unit 201, and an arrival angle specification unit 202.

The phase difference detection unit 200 selects a plurality of combinations of two antenna elements from among the three antenna elements (first antenna element 10a to third antenna element 10c, see FIG. 3) arranged along the reference line. Then, the phase difference (phase differences φ ₁ and φ ₂ shown in FIG. 3) of the incoming wave E received by the two antenna elements related to the combination is detected.
Specifically, the phase difference detection unit 200 first selects a combination of the first antenna element 10a and the second antenna element 10b, and the arrival received by each of the first antenna element 10a and the second antenna element 10b. It detects the phase difference phi ₁ of the wave E. Similarly, the phase difference detection unit 200 selects a combination of the first antenna element 10a and the third antenna element 10c, and the order of the incoming wave E received by each of the first antenna element 10a and the third antenna element 10c. phase difference φ ₂ to detect.
The phase difference detection unit 200 may be an existing phase difference detection circuit or the like that can generate a detection signal corresponding to the phase difference between two input signal waveforms (signal waveforms based on the incoming wave E). Moreover, the aspect provided with two or more for the phase difference detection part 200 according to the some combination from which any two among three antenna elements were selected may be sufficient. For example, the angle detection device 20A includes a phase difference detection unit 200 in which the first antenna element 10a and the second antenna element 10b are connected, and a phase difference detection in which the first antenna element 10a and the third antenna element 10c are connected. The aspect provided with the part 200 separately may be sufficient.

The candidate value calculation unit 201 includes a phase difference (phase difference φ ₁ , φ ₂ ) detected by the phase difference detection unit 200 and an interval (interval d ₁ , two antenna elements) related to the combination used for detecting the phase difference. d ₂ ) and a candidate value for the arrival angle θ of the incoming wave E is calculated.
The arrival angle specifying unit 202 specifies the detection value of the arrival angle θ based on the candidate value calculated by the candidate value calculation unit 201 for each of the plurality of combinations of the two antenna elements.

(Function of angle detector)
4 and 5 are first and second diagrams illustrating functions of the angle detection device according to the first embodiment.
FIG. 4 shows an example in which an incoming wave E is incident on the array antenna 10A at an incoming angle θ = 65 °.
In this case, the phase difference φ ₁ between the incoming wave E received by the first antenna element 10a and the incoming wave E received by the second antenna element 10b is determined by the interval d ₁ (= 0.6λ) and the equation (1). In this case, φ ₁ = 195.8 °. The phase difference detection unit 200 detects the phase difference φ ₁ = 195.8 ° related to the combination of the first antenna element 10a and the second antenna element 10b.

Here, the candidate value calculation unit 201, a phase difference phi ₁ to the phase difference detecting unit 200 detects, two antenna elements according to the combination used for detection of the phase difference phi ₁ (first antenna element 10a and the second Based on the distance d ₁ of the antenna element 10b), a candidate value for the arrival angle θ of the incoming wave E is calculated. Specifically, the candidate value calculation unit 201 substitutes the phase difference φ ₁ (= 195.8 °) detected by the phase difference detection unit 200 into Expression (3) that is an inverse function of Expression (1). in, and calculates the candidate values theta ₁₁ of the arrival angle theta.

Thereby, the candidate value calculation unit 201 calculates the candidate value θ ₁₁ = 65 ° of the arrival angle θ.

However, the phase difference phi ₁ acquired by detecting the phase difference detecting unit 200 actually has uncertainty ± 360 ° (2π) × n (n is an integer). That is, the true phase difference between the incoming waves E received by the incoming wave E has received the second antenna element 10b in the first antenna element 10a is, with respect to the detected phase difference phi _1, actually more, n cycles There is a possibility of deviation (± 360 ° × n).
For example, depending on the specifications of the phase difference detection unit 200, a case where a phase difference of -164.2 ° is detected as φ ₁ = 195.8 ° (= −164.2 ° + 360 °) can be considered.

Here, for example, it is assumed that the array antenna 10A receives an incoming wave having an arrival angle θ ′ = − 49.5 ° (referred to as a virtual incoming wave E ′). In this case, the phase difference between the incoming wave E received by the first antenna element 10a and the incoming wave E received by the second antenna element 10b is -164.2 °. However, depending on the specifications of the phase difference detection unit 200, the phase difference of −164.2 ° can be detected as the phase difference φ ₁ = 195.8 ° (= −164.2 ° + 360 °). Then, only by the information of the phase difference φ ₁ = 195.8 ° detected by the phase difference detection unit 200, whether the arrival wave E has arrived at the arrival angle θ = 65 ° or the arrival angle θ ′ = − 49.5. It is indistinguishable whether it arrived at ° (see virtual incoming wave E ′ shown in FIG. 4).

Therefore, the candidate value calculation unit 201 substitutes the phase difference (φ ₁ −360 °) in addition to the candidate value θ ₁₁ calculated by substituting the detection result (phase difference φ ₁ ) of the phase difference detection unit 200 into the equation (3). ), (Φ ₁ −720 °), and (φ ₁ + 360 °) are substituted into Equation (3) to calculate other candidate values θ ₁₂ , θ ₁₃ , and θ ₁₄ . For example, the candidate value θ ₁₂ based on the phase difference (φ ₁ -360 °) is calculated based on the following equation (4).

The calculation formulas for the candidate value θ ₁₃ based on the phase difference (φ ₁ -720 °) and the candidate value θ ₁₄ based on the phase difference (φ ₁ + 360 °) are also the same.

FIG. 5 shows the relationship between the four arrival angle candidate values θ ₁₁ , θ ₁₂ , θ ₁₃ , and θ ₁₄ obtained by the above calculation and the true value θ ₀ of the arrival angle.
As shown in FIG. 5, for example, when the candidate value calculation unit 201 receives the phase difference φ ₁ = 195.8 ° from the phase difference detection unit 200, the candidate phase calculation unit 201 receives the phase difference φ ₁ = 195.8 °, and Then, two candidate values θ ₁₁ = 65 ° and θ ₁₂ = −49.5 ° corresponding to each of the phase difference (φ ₁ −360 °) = − 164.2 ° are calculated.
For example, when the candidate value calculation unit 201 receives the phase difference φ ₁ = 108.0 ° from the phase difference detection unit 200, the candidate value calculation unit 201 has only one corresponding to the phase difference φ ₁ = 108.0 °. The candidate value θ ₁₁ = 30 ° is calculated.

6 and 7 are third and fourth diagrams illustrating the function of the angle detection device according to the first embodiment.
FIG. 6 shows an example in which an incoming wave E is incident on the array antenna 10A at an incoming angle θ = 25 °.
In this case, the phase difference φ ₂ between the incoming wave E received by the first antenna element 10a and the incoming wave E received by the third antenna element 10c is determined by the interval d ₂ (= 1.3λ) and the equation (2). Φ ₂ = 197.8 °. The phase difference detection unit 200 detects the phase difference φ ₂ = 197.8 ° related to the combination of the first antenna element 10a and the third antenna element 10c.

Here, the candidate value calculation unit 201, a phase difference phi ₂ to the phase difference detecting unit 200 detects, two antenna elements according to the combination used for detection of the phase difference phi ₂ (first antenna element 10a and the third Based on the distance d ₂ of the antenna element 10c), a candidate value for the arrival angle θ of the incoming wave E is calculated. Specifically, the candidate value calculation unit 201 substitutes the phase difference φ ₂ (= 197.8 °) detected by the phase difference detection unit 200 into the equation (5), so that the candidate value θ of the arrival angle θ. ₂₁ is calculated.

Thereby, the candidate value calculation unit 201 calculates the candidate value θ ₂₁ = 25 ° of the arrival angle θ.

However, the phase difference phi ₂ acquired by detecting the phase difference detecting unit 200, similarly to the above, in fact, has uncertainty ± 360 ° (2π) × n . That is, the true phase difference between the incoming waves E received by the incoming wave E received by the first antenna element 10a third antenna element 10c, compared detected phase difference phi _2, further, n cycles (± 360 ° x n) There is a possibility of deviation.

Here, for example, it is assumed that the array antenna 10A separately receives an incoming wave having an arrival angle θ ′ = − 20.3 ° (virtual incoming wave E ′ shown in FIG. 6). In this case, the phase difference between the incoming wave E received by the first antenna element 10a and the incoming wave E received by the third antenna element 10c is -162.2 °. However, depending on the specifications of the phase difference detection unit 200, the phase difference of −162.2 ° can be detected as the phase difference φ ₂ = 197.8 ° (= −162.2 ° + 360 °). Then, only by the information that the phase difference φ ₂ = 197.8 ° detected by the phase difference detection unit 200, whether the incoming wave E has arrived at the arrival angle θ = 25 °, or the arrival angle θ ′ = − 20.3. It is impossible to distinguish whether it arrived at ° (see virtual incoming wave E ′ shown in FIG. 6).

Therefore, the candidate value calculation unit 201 substitutes the phase difference (φ ₂ −360 °) in addition to the candidate value θ ₂₁ calculated by substituting the output value (phase difference φ ₂ ) of the phase difference detection unit 200 into the equation (5). ), (Φ ₂ −720 °), and (φ ₂ + 360 °) are substituted into Equation (5) to calculate other candidate values θ ₂₂ , θ ₂₃ , and θ ₂₄ . For example, the candidate value θ ₂₂ based on the phase difference (φ ₂ −360 °) is calculated based on the following equation (6).

The arithmetic expressions for the candidate value θ ₂₃ based on the phase difference (φ ₂ −720 °) and the candidate value θ ₂₄ based on the phase difference (φ ₂ + 360 °) are the same.

FIG. 7 shows the relationship between the four arrival angle candidate values θ ₂₁ , θ ₂₂ , θ ₂₃ , and θ ₂₄ obtained by the above calculation and the true value θ ₀ of the arrival angle.
As illustrated in FIG. 7, for example, when the candidate value calculation unit 201 receives a phase difference φ ₂ = 197.8 ° from the phase difference detection unit 200, the candidate value calculation unit 201 receives the phase difference φ ₂ = 197.8 °, and Then, two candidate values θ ₂₁ = 25 ° and θ ₂₂ = −20.3 ° corresponding to each of the phase difference (φ ₂ −360 °) = − 162.2 ° are calculated.
For example, when the candidate value calculation unit 201 receives the phase difference φ ₂ = 81.3 ° from the phase difference detection unit 200, the candidate value calculation unit 201 receives the phase difference φ ₂ = 81.3 °, the phase difference (φ ₂ − 360 °) = − 278.7 ° and three candidate values corresponding to each of the phase difference (φ ₂ + 360 °) θ ₂₁ = 25 °, θ ₂₂ = −20.3 ° and θ ₂₄ = 70.5 Calculate °.

Next, the function of the arrival angle specifying unit 202 will be specifically described with reference to FIGS. 5 and 7.
The arrival angle specifying unit 202 is based on the candidate values calculated by the above processing of the candidate value calculation unit 201 for each of a plurality of combinations of the first antenna element 10a, the second antenna element 10b, and the third antenna element 10c. Specifically, the arrival angle detection unit 202 specifies a plurality of candidate values θ ₁₁ , θ ₁₂ , θ calculated for the combination of the first antenna element 10a and the second antenna element 10b. ₁₃ and θ _14, and a plurality of candidate values θ ₂₁ , θ ₂₂ , θ ₂₃ , and θ ₂₄ calculated for the combination of the first antenna element 10 a and the third antenna element 10 c are referred to. Then, the arrival angle specifying unit 202 sets one candidate value common to any one of the candidate values θ ₂₁ , θ ₂₂ , θ ₂₃ , and θ ₂₄ among the candidate values θ ₁₁ , θ ₁₂ , θ ₁₃ , and θ ₁₄ . The detected value θd is specified.

For example, the candidate value calculation unit 201 calculates two candidate values θ ₁₁ = 65 ° and θ ₁₂ = −49.5 ° from the phase difference φ ₁ = 195.8 ° acquired through the phase difference detection unit 200. (See FIG. 5). Similarly, from the phase difference φ ₂ = 424.2 ° acquired by the candidate value calculation unit 201 through the phase difference detection unit 200, three candidate values θ ₂₁ = 65 °, θ ₂₂ = −7.9 °, −39 Assume that 2 ° is calculated (see FIG. 7).
In this case, the arrival angle specifying unit 202 includes the first antenna element 10a among the candidate values θ ₁₁ = 65 ° and θ ₁₂ = −49.5 ° related to the combination of the first antenna element 10a and the second antenna element 10b. As a candidate value common to any one of the candidate values θ ₂₁ = 65 °, θ ₂₂ = −7.9 °, and −39.2 ° related to the combination of the third antenna element 10c and θ ₁₁ (= Select θ ₂₁ ) = 65 °. Then, the arrival angle specifying unit 202 specifies the selected θ ₁₁ = 65 ° as the detection value θd = 65 ° to be output.
As shown in FIGS. 5 and 7, the true value θ ₀ of the arrival angle θ in the above case is θ ₀ = 65 °, and the detected value θd specified by the arrival angle specifying unit 202 is the true value θ _0. It matches.

(Function and effect)
According to the angle detection apparatus 20A according to the first embodiment, first, the phase difference detection unit 200 includes three or more antenna elements (first antenna element 10a to third antenna element 10c) arranged along the reference line. ), A plurality of combinations composed of two antenna elements are selected, and the phase differences φ ₁ and φ ₂ of the incoming wave E received by the two antenna elements related to the combination are detected.
Based on the phase differences φ ₁ , φ ₂ and the distances d ₁ , d ₂ between the two antenna elements related to the combination used for detecting the phase differences φ ₁ , φ ₂ The candidate values θ _{11 to} θ ₁₄ and θ _{21 to} θ ₂₄ of the arrival angle θ of the incoming wave E are calculated.
Furthermore, the arrival angle specifying unit 202 specifies the detected value θd of the arrival angle θ based on the candidate values θ _{11 to} θ ₁₄ and θ _{21 to} θ ₂₄ calculated for each of the plurality of combinations.

By doing so, it is a case where the solution (candidate values θ ₁₁ , θ ₁₂ ... Of arrival angles) cannot be specified as one by just combining a set of antenna elements due to the uncertainty of the phase difference. In addition, the accuracy of the solution can be improved by narrowing down with reference to solutions (candidate values of arrival angles θ ₂₁ , θ ₂₂ ...) Obtained from a combination of another set of antenna elements. Therefore, even when the incident light is incident from the arrival angle θ that cannot be identified as a single solution, it is possible to accurately detect the incident light from the incoming angle θ.
That is, according to the angle detection device 20A according to the first embodiment, it is possible to suppress erroneous recognition of the arrival angle of electromagnetic waves.

In addition, as described above, the angle detection device 20A according to the first embodiment has another combination among a plurality of candidate values (candidate values θ ₁₁ , θ ₁₂ ,...) Calculated for one combination. One candidate value common to any one of the plurality of candidate values (candidate values θ ₂₁ , θ ₂₂ ,...) Calculated for is specified as the detected value θd.

In this way, since the detected value θd of the arrival angle θ can be narrowed down to one candidate value that is common across different combinations of antenna elements, a plurality of candidate values (candidate values θ ₁₁ , θ ₁₂ ,...) Can be selected as the detection value θd.
Here, the phrase “common” is not limited to the meaning that the two candidate values need to be completely matched, and the two candidate values are included within a predetermined error tolerance range. The meaning of is included.

Further, in the angle detection device 20A according to the first embodiment, the distance between two antenna elements according to one combination (interval d ₁ ) is equal to the distance between two antenna elements according to another combination (interval d ₂ ). A combination that does not become an integral multiple of is selected (for example, d ₁ = 0.6λ, d ₂ = 1.3λ).

Here, when the interval (interval d ₁ ) of the antenna elements related to one combination is an integral multiple of the interval (interval d ₂ ) of the antenna elements related to another combination (for example, d ₁ = m × d _2). , M is an integer), a common candidate value cannot be narrowed down to one for each combination. That is, among a plurality of candidate values (candidate values θ ₁₁ , θ ₁₂ ,...) Calculated for one combination, a plurality of candidate values (candidate values θ ₂₁ , θ ₂₂ ,. There are cases where two or more candidate values in common with ..) are specified.
Then, the candidate values that are common to both the plurality of candidate values calculated for one combination and the plurality of candidate values calculated for the other combination cannot be specified as one, and the candidate value is calculated. Depending on the result, it becomes difficult to obtain a highly accurate detection value θd. Therefore, by arranging the distances d ₁ and d ₂ between the antenna elements so as not to satisfy the above relationship (d ₁ ≠ m × d ₂ ), the incident angle can be any angle. , It is always possible to uniquely identify a common solution.

As described above, the first embodiment has been described in detail. However, the specific aspect of the wireless communication system 1A according to the first embodiment is not limited to the above-described one and is within the scope not departing from the gist. Various design changes and the like can be added.
For example, the array antenna 10A according to the first embodiment includes three antenna elements (first antenna element 10a to third antenna element 10c) along a reference line (X axis (FIG. 2)) on the substrate 11. Although described as being arranged at a predetermined interval, the array antenna 10A according to another embodiment is not limited to this.
That is, an array antenna 10A according to another embodiment has a fourth antenna element on the reference line in addition to the first antenna element 10a to the third antenna element 10c, and four or more antenna elements are arranged. It may be an embodiment.
Further, the angle detection device 20A may calculate candidate values for combinations of three or more antenna elements.

In addition, the angle detection device 20A according to the first embodiment has one common with any one of a plurality of candidate values calculated for another combination among a plurality of candidate values calculated for one combination. The candidate value is specified as the detection value θd, but is not limited to this aspect in other embodiments.
For example, the angle detection device 20A (arrival angle specifying unit 202) has a plurality of candidate values (for example, candidate values θ ₁₁ , θ ₁₂ ,..., Candidate values θ ₂₁ , θ for combinations of three or more antenna elements). ₂₂ ,..., The candidate values θ ₃₁ , θ ₃₂ ,...) Are calculated, the mode value of the candidate values may be specified as the detected value θd. Here, candidate values θ ₁₁ , θ ₁₂ ,... Are candidate values for the first set, candidate values θ ₂₁ , θ ₂₂ ,... Are candidate values for the second set, and candidate values θ ₃₁ , θ ₃₂ ,... Are candidate values for the third set.
In this way, the candidate value that is common to the largest number of combinations among the plurality of candidate values is specified as the detected value θd, and therefore, the detected value θd with higher accuracy than the true value θ ₀ of the arrival angle. Can be obtained.

Further, the angle detection device 20A according to the first embodiment obtains a maximum of four candidate values (candidate values θ ₁₁ , θ ₁₂ , θ ₁₃ , θ ₁₄ ) based on the detected one phase difference φ _1. Although described as what is calculated, other embodiments are not limited to this mode.
For example, the angle detection device 20A (candidate value calculation unit 201) sets five or more candidate values calculated based on the phase difference (φ ₁ + 720 °) and the like based on the detected phase difference φ _1. It may be calculated.

In addition, the angle detection device 20A (phase difference detection unit 200) according to another embodiment includes a combination of two antenna elements arranged with one or more antenna elements sandwiched among a plurality of combinations of antenna elements. May be included. For example, the angle detection device 20A selects a combination of the first antenna element 10a and the third antenna element 10c arranged with the second antenna element 10b interposed therebetween.
Here, when there is no large difference between the intervals (intervals d ₁ , d ₂ ) of the antenna elements related to the selected combinations, a plurality of candidate values (candidate values θ ₁₁ , θ ₁₂ , ..) And a plurality of candidate values (candidate values θ ₂₁ , θ ₂₂ ,...) Calculated for other combinations are assumed to be similar to each other. Then, the angle detection device 20A cannot specify one candidate value common to both.
However, as in the other embodiments described above, by always including a combination of two antenna elements arranged with one or more antenna elements in between, the distance between the antenna elements according to the combination of one antenna element and the other The difference between the antenna elements according to the combination of the antenna elements can be increased. Therefore, the angle detection device 20A can specify the arrival angle with higher accuracy.

<Second Embodiment>
Next, a radio communication system according to the second embodiment will be described with reference to FIGS.

FIG. 8 is a diagram illustrating a functional configuration of a wireless communication system according to the second embodiment.
As shown in FIG. 8, the angle detection apparatus 20A according to the second embodiment further includes a signal processing unit 203 in addition to the configuration of the first embodiment.
The signal processing unit 203 calculates an estimated value θs of the arrival angle θ of the incoming wave E based on signal processing for the amplitude and phase of the incoming wave E received by three or more antenna elements provided in the array antenna 10A.
Here, the signal processing unit 203 performs signal processing based on a beam former method, which is a known method for estimating the arrival angle θ of the electromagnetic wave (arrival wave E). The beamformer method uses an array antenna in which three or more antenna elements are arranged along a reference line, and causes the main lobe of the array antenna 10A (range angle having the highest radiation characteristic per array antenna 10A) to extend in all directions. This is a method of scanning and searching for a direction in which the output power of the array antenna 10A increases. In the beam former method, vector calculation (calculation using an amplitude value and a phase value) is performed for an incoming wave E received by each antenna element. Therefore, the estimated value θs of the arrival angle estimated by the signal processing unit 203 is a value calculated based on the detected value θd (phase differences φ ₁ and φ ₂₎ specified by the arrival angle specifying unit 202 according to the first embodiment. ) And higher accuracy.

However, also in the beamformer method, the signal waveform acquired through the array antenna 10A has an uncertainty of ± 360 ° (2π) × n as described above. That is, depending on the arrival angle θ of the incoming wave E, the arrival angle θ may not be uniquely estimated even with the beamformer method. Therefore, the designer of the angle detection device 20A normally knows in advance the estimable maximum angle θmax that defines the condition (range of the arrival angle θ) by which the arrival angle θ can be uniquely estimated by the beamformer method.
Here, the estimable maximum angle θmax is defined as, for example, the arrival angle θ that gives the phase difference φ ₁ = 180 ° (π) in Equation (1). That is, the condition that the absolute value of the arrival angle θ falls within the range of 180 ° to −180 ° of the phase difference φ ₁ of the incoming wave E received by each of the first antenna element 10a and the second antenna element 10b (| θ | when ≦ .theta.max) meet, without taking into account the uncertainty of the phase difference phi _1, it can be estimated uniquely correct arrival angle theta.

  In this case, the estimable maximum angle θmax is defined by the following equation (7).

On the other hand, the arrival angle identifying unit 202 according to the second embodiment identifies based on candidate values (for example, candidate values θ ₁₁ , θ ₁₂ ,..., Candidate values θ ₂₁ , θ ₂₂ ,...). When the detected value θd is within the estimable range corresponding to the signal processing (beamformer method), the estimated value θs calculated based on the signal processing is specified as the detected value θd.

FIG. 9 is a diagram illustrating a processing flow of the angle detection apparatus according to the second embodiment.
A specific processing flow of the angle detection apparatus 20A according to the second embodiment will be described step by step with reference to FIG.
Here, the processing flow shown in FIG. 9 is started when the toll collection facility 1 detects that the vehicles A1 and A2 have arrived in the communicable areas Q1 and Q2 (see FIG. 1).

First, the angle detection device 20A specifies the detection value θd by the processing of the phase difference detection unit 200, the candidate value calculation unit 201, and the arrival angle specification unit 202 according to the first embodiment (step S01). Specifically, candidate values (candidate values θ ₁₁ , θ ₁₂ ,..., Θ ₂₁ , θ ₂₂₎ for each combination of antenna elements according to the phase differences φ ₁ and φ ₂ detected by the phase difference detection unit 200. ,..., And one detected value θd is specified based on the candidate value.

  Next, the arrival angle specifying unit 202 determines whether or not the detected value θd specified based on the candidate value is within an estimable range corresponding to signal processing based on the beamformer method (step S02). Specifically, the arrival angle specifying unit 202 determines whether or not the detected value θd satisfies | θd | ≦ θmax.

When | θd | ≦ θmax is satisfied (step S02: YES), the signal processing unit 203 performs signal processing based on the beamformer method, and calculates the estimated value θs of the arrival angle. Then, the arrival angle specifying unit 202 specifies the estimated value θs calculated by the signal processing unit 203 as the detected value θd (step S03).
On the other hand, when | θd |> θmax is satisfied (step S02: NO), the angle detection device 20A determines that the correct estimated value θs of the arrival angle cannot be calculated by the beamformer method, and performs the signal processing. Do not do.

  The arrival angle specifying unit 202 outputs the detection value θd specified through the above steps S01 to S03 (step S04), and ends a series of processing.

(Function and effect)
As described above, according to the angle detection device 20A according to the second embodiment, the signal processing unit 203 performs signal processing (beamformer method) on the amplitude and phase of the incoming wave E received by three or more antenna elements. Based on this, an estimated value θs of the arrival angle of the incoming wave E is calculated. When the detected value θd specified based on the candidate values θ ₁₁ , θ _12, etc. is within the estimable range according to the signal processing (| θd | ≦ θmax) The estimated value θs is specified as the detected value θd.

In this way, when it is expected that electromagnetic waves are coming from a range where the solution (estimated value θs) can be uniquely specified based on the beamformer method, the arrival angle estimation based on the beamformer method is separately performed. Processing is performed, and an estimated value θs that is a calculation result can be output.
Therefore, it is possible to obtain a detection result with higher accuracy than the angle detection device 20A according to the first embodiment.
On the other hand, when it is expected that no electromagnetic wave has arrived from a range where the solution can be uniquely specified based on the beamformer method, the detection value θd obtained by the method according to the first embodiment is directly adopted and output. To do. As a result, the arrival angle θ can be detected even when electromagnetic waves arrive from outside the range that can be estimated by the beamformer method.

  Note that the specific mode of signal processing performed by the signal processing unit 203 according to the second embodiment is not limited to that based on the above-described “beamformer method”. That is, signal processing based on other methods used for arrival angle estimation may be employed. Specifically, the signal processing unit 203 may perform signal processing based on a “Capon method”, a “MUSIC (Multiple Signal Classification) method”, a “linear prediction method”, or the like, which is a further development of the “beamformer method”. Good.

In each of the above-described embodiments, a program for realizing various functions of the angle detection device 20A is recorded on a computer-readable recording medium, and the program recorded on the recording medium is read by a computer system. Various processes are performed by executing. Here, various processes of the angle detection device 20A described above are stored in a computer-readable recording medium in the form of a program, and the above-described various processes are performed by the computer reading and executing the program. The computer-readable recording medium is a magnetic disk, a magneto-optical disk, a CD-ROM, a DVD-ROM, a semiconductor memory, or the like. Alternatively, the computer program may be distributed to the computer via a communication line, and the computer that has received the distribution may execute the program.
Moreover, the aspect with which the various functions of 20 A of angle detection apparatuses are comprised over the some apparatus connected with a network may be sufficient.

  As mentioned above, although some embodiment of this invention was described, these embodiment is shown as an example and is not intending limiting the range of invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the invention described in the claims and equivalents thereof, as long as they are included in the scope and gist of the invention.

1 Toll collection facility 1A Wireless communication system 10 Wireless communication device 10A Array antenna 10a First antenna element 10b Second antenna element 10c Third antenna element 11 Substrate 20 Roadside system 20A Angle detector 200 Phase difference detector 201 Candidate value calculator 202 Arrival angle specifying unit 203 Signal processing unit 30 Entering side vehicle detector 40 Start control device 50 Starting side vehicle detector A1, A2 Vehicle L1, L2 Lane Q1, Q2 Communicable area R Ceiling E Arrival wave E 'Virtual arrival wave d ₁ , D ₂ antenna element distance Δ ₁ , Δ ₂ path difference φ ₁ , φ ₂ phase difference θ arrival angle θ ₀ arrival angle true value θ ₁₁ , θ ₁₂ , θ ₁₃ , θ ₁₄ arrival angle candidate value θ ₂₁ , θ ₂₂ , θ ₂₃ , θ ₂₄ arrival angle candidate values θd arrival angle detection value θmax maximum estimable angle

Claims (9)

A plurality of combinations of the two antenna elements are selected from three or more antenna elements arranged along a reference line, and a phase difference between incoming waves received by the two antenna elements according to the combination is detected. A phase difference detector;
A candidate value calculation unit that calculates a candidate value of an arrival angle of the incoming wave based on the phase difference and an interval between the two antenna elements according to the combination used for detecting the phase difference;
Based on the candidate values calculated for each of a plurality of the combinations, an arrival angle specifying unit that specifies a detection value of the arrival angle;
An angle detection device comprising: The phase difference detector is
The angle detection device according to claim 1, wherein a plurality of combinations in which an interval between two antenna elements related to one combination is not an integral multiple of an interval between two antenna elements related to another combination are selected. The phase difference detector is
The angle detection device according to claim 1, wherein the plurality of combinations include a combination of two antenna elements arranged with one or more antenna elements interposed therebetween. The arrival angle specifying unit includes:
One candidate value that is common to any one of the plurality of candidate values calculated for the other combination among the plurality of candidate values calculated for the one combination is specified as the detected value. The angle detection device according to any one of claims 1 to 3. A signal processing unit that calculates an estimated value of an arrival angle of the incoming wave based on signal processing with respect to amplitude and phase of the incoming wave received by three or more antenna elements;
The arrival angle specifying unit includes:
The estimated value calculated based on the signal processing is specified as the detected value when the detected value specified based on the candidate value is within an estimable range corresponding to the signal processing. The angle detection device according to any one of claims 1 to 4. The arrival angle specifying unit includes:
The detected value (θ [rad]) specified based on a plurality of candidate arrival angle values is the wavelength (λ [m]) of the incoming wave, and the interval (d [ m]), the estimated value calculated based on the signal processing is used as the detected value when it is within the estimable range that satisfies the condition | θ | <sin ⁻¹ (λ / 2d). The angle detection device according to claim 5. The angle detection device according to any one of claims 1 to 6,
An array antenna that has three or more antenna elements and receives the incoming waves from the vehicle-mounted device mounted on a vehicle traveling in a lane;
A wireless communication system. A plurality of combinations of the two antenna elements are selected from three or more antenna elements arranged along a reference line, and a phase difference between incoming waves received by the two antenna elements according to the combination is detected. Steps,
Calculating a candidate value of the arrival angle of the incoming wave based on the phase difference and an interval between the two antenna elements according to the combination used for detecting the phase difference;
Identifying a detection value of the arrival angle based on the candidate values calculated for each of the plurality of the combinations;
An angle detection method comprising: Computer of angle detection device,
A plurality of combinations of the two antenna elements are selected from three or more antenna elements arranged along a reference line, and a phase difference between incoming waves received by the two antenna elements according to the combination is detected. Phase difference detection means,
Candidate value calculation means for calculating a candidate value of an arrival angle of the incoming wave based on the phase difference and an interval between the two antenna elements related to the combination used for detecting the phase difference;
An arrival angle specifying means for specifying a detection value of the arrival angle based on the candidate value calculated for each of a plurality of the combinations;
Program to function as.

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