Estimation device and estimation method

Abstract

To provide an estimation device and an estimation method capable of precisely estimating an azimuth angle of an arrival direction of a signal even under an environment having different antenna heights among transceivers.SOLUTION: An estimation device 1 includes: a reception device 10 having multiple antenna elements Rx_0 to Rx_N-1 for receiving a transmission signal transmitted from a transmission antenna of a transmission station as a reception signal; a signal recording device 13 for recording data of a reception signal; an array response output device 15 for outputting an array response vector based on zenith angle prior information θprior that is an assumed value of a zenith angle in an arrival direction of a transmission signal; an angle spectrum estimation section 21 for estimating an azimuth angle spectrum S(φ) of a transmission signal from data of the array response vector and a reception signal; and an arrival direction estimation section 22 for estimating an azimuth angle of each peak included in the azimuth angle spectrum S(φ) estimated by the angle spectrum estimation section 21 as an azimuth angle of an arrival direction of a transmission signal.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an estimation device and an estimation method for estimating the direction of arrival of radio waves. [Background technology]

[0002] Estimation of the direction of arrival of radio waves can be applied to various fields, such as estimating the position of a wireless communication terminal, identifying illegal radio wave sources, and beam management, and high-resolution estimation methods using array antennas are being studied. As shown in Fig. 14, a conventional estimation method estimates the azimuth angle φ of the direction of arrival using an array response assuming that the zenith angle θ of the direction of arrival of a signal incident from the transmitting antenna of a transmitting station to the receiving antenna Rx of a receiving device 100 is 90 degrees.

[0003] For example, Patent Document 1 and Non-Patent Document 1 disclose an estimation method using Multiple Signal Classification (MUSIC) based on a subspace method that uses eigenvalue decomposition of the correlation matrix of a received signal. Non-Patent Document 2 discloses an estimation method using compressed sensing that focuses on the sparsity of the angle space. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5135595 [Non-patent literature]

[0005] [Non-Patent Document 1] R. Schmidt, "Multiple emitter location and signal parameter estimation," IEEE Transactions on Antennas and Propagation, Vol. 34, No. 3, pp. 276-280, Mar. 1986. [Non-patent document 2] H. Suganuma, K. Takizawa, T. Kobayashi, I. Otani, and T. Mitsui,"Impact of antenna directivity on compressed sensing-based DOA estimation employing UCA antenna," IEICE Communications Express, Vol. 12, No. 4, pp. 132-138, Apr. 2023. Summary of the Invention [Problem to be solved by the invention]

[0006] In recent years, the fifth generation mobile communication system has been put into operation as a mobile communication system, and the number of compatible wireless communication terminals is increasing. Among these, millimeter waves, which have high frequencies that enable ultra-high speed communication, are also used. Millimeter wave radio waves have the characteristics of strong directionality, vulnerability to obstruction, and large attenuation over distance.

[0007] That is, since millimeter-wave communications are expected to have a relatively narrow coverage area and a short distance between transmitter and receiver, millimeter-wave transmitting antennas are installed at high positions to ensure line of sight. As a result, as shown in Figures 14 and 15, due to differences in antenna height between transmitter and receiver, the actual zenith angle θ of the arrival direction of the transmitted signal from the transmitting antenna Tx of the transmitting station is an angle other than 90 degrees.

[0008] For example, when the receiving device 100 is installed on the ground and the transmitting antenna Tx of the transmitting station is installed on the roof of a building, the zenith angle θ is smaller than 90°. When the receiving device 100 is mounted on a drone and placed higher in the sky than the transmitting antenna Tx, the zenith angle θ is larger than 90°.

[0009] However, the conventional methods disclosed in Patent Document 1, Non-Patent Document 1, and Non-Patent Document 2 use an array response assuming that the zenith angle θ is 90 degrees, and therefore have a problem in that the accuracy of direction-of-arrival estimation deteriorates when the antenna heights of the transmitter and receiver are different.

[0010] The present invention has been made to solve the above-mentioned conventional problems, and aims to provide an estimation device and an estimation method that can accurately estimate the azimuth angle of the direction of arrival of a signal even in an environment where the antenna heights of a transmitter and a receiver are different. [Means for solving the problem]

[0011] In order to solve the above problem, the estimation device according to the present invention includes a receiving device (10) having a plurality of antenna elements (Rx_0 to Rx_N-1) that receives a transmission signal transmitted from a transmitting antenna of a transmitting station as a received signal, a signal recording device (13) that records data of the received signal, and zenith angle prior information that is an estimated value of the zenith angle of the arrival direction of the transmission signal. θ prior and a radiation pattern of the plurality of antenna elements. an angle spectrum estimator (21) for estimating the azimuth angle spectrum of the transmission signal from the array response vector and data of the received signal; and a frequency spectrum estimator (22) for estimating the azimuth angle of each peak included in the azimuth angle spectrum estimated by the angle spectrum estimator (21) relative to the azimuth angle of the direction of arrival of the transmission signal. φ and an arrival direction estimation unit (22) that estimates the arrival direction as follows: The array response vector is expressed by the following formula (1), and each element of the array response vector is expressed by the following formula (2), The plurality of antenna elements are a uniform circular array antenna. The antenna elements have directivities in different directions, and the angular spectrum estimation unit uses FISTA, a compressed sensing algorithm. It is a composition.

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[0012] With this configuration, the estimation device according to the present invention can accurately estimate the azimuth angle of the arrival direction of a transmitted signal even in an environment where the antenna heights of the transmitter and receiver are different, i.e., even if the zenith angle of the arrival direction of the transmitted signal is an angle other than 90 degrees.

[0013] Moreover, the estimation device according to the present invention may be configured to further include an elevation angle measurement device (40) that measures an elevation angle of the transmitting antenna as seen from a central position of the plurality of antenna elements, and the zenith angle advance information may be a value of the elevation angle measured by the elevation angle measurement device.

[0014] With this configuration, the estimation device according to the present invention can accurately estimate the azimuth angles of the directions of arrival of the direct wave and reflected wave of the transmitted signal, even in a so-called multipath situation in which both the direct wave and the reflected wave of the transmitted signal are incident on multiple antenna elements.

[0015] In addition, in the estimation device according to the present invention, the elevation angle measurement device is a level with a laser or a finder, and is configured to measure the elevation angle of the transmitting antenna of the transmitting station located on a line of sight from the central position of the plurality of antenna elements. In addition, the estimation device according to the present invention further includes an operation device (14) that selects a radio environment scenario through an operation input by a user, and the operation device is configured to select the zenith angle prior information by selecting the radio environment scenario. Furthermore, in the estimation device according to the present invention, when the operation device selects the radio environment scenario, the operation device sets the zenith angle advance information that reduces an estimation error in the direction of arrival in the array response output device (15), and the estimation error is a root mean squared error (RMSE) between an azimuth angle estimated by computer simulation and an actual known azimuth angle. The estimation method according to the present invention includes a step (S3) of receiving a transmission signal transmitted from a transmission antenna of a transmitting station as a received signal by a plurality of antenna elements (Rx_0 to Rx_N-1), a step (S4) of recording data of the received signal, and a step (S5) of recording zenith angle a priori information which is an estimated value of the zenith angle of the arrival direction of the transmission signal. θ prior and a radiation pattern of the plurality of antenna elements. a step (S5) of outputting an array response vector based on the above; an angular spectrum estimation step (S6) of estimating an azimuth angle spectrum of the transmission signal from the array response vector and data of the reception signal; and φ and (S7) estimating the The array response vector is expressed by the following formula (1), and each element of the array response vector is expressed by the following formula (2), The plurality of antenna elements are a uniform circular array antenna. The antenna elements have directivities in different directions, and the angular spectrum estimation step uses FISTA, a compressed sensing algorithm. It is a composition.

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[0016] The present invention provides an estimation device and estimation method that can accurately estimate the azimuth angle of the direction of arrival of a signal even in an environment where the antenna heights of a transmitter and a receiver are different. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a diagram illustrating a configuration of an estimation device according to a first embodiment of the present invention. [Figure 2]1A and 1B are schematic diagrams showing the configuration of a receiving device included in an estimation device according to a first embodiment of the present invention, in which (a) is a perspective view and (b) is a plan view. [Figure 3] 10 is a table showing an example of types of radio environment scenarios and zenith angle advance information associated with each radio environment scenario. [Figure 4] 1 is a graph showing a unit vector representing the direction of arrival of a transmitted signal. [Figure 5] FIG. 1 is a diagram illustrating the concept of direction of arrival estimation based on compressed sensing. [Figure 6] 3 is a graph schematically showing an azimuth angle spectrum estimated by a signal processing device included in the estimation device according to the first embodiment of the present invention. [Figure 7] 10 is a graph showing the radiation patterns in the horizontal plane of four antenna elements used in a computer simulation. [Figure 8] 1 is a table showing parameters used in a computer simulation. [Figure 9] 10 is a graph showing an estimation error of an azimuth angle estimated by computer simulation. [Figure 10] 10 is a graph showing, for each radio environment scenario, the estimation error when the zenith angle prior information is 90 degrees, among the estimation errors of the azimuth angle shown in FIG. 9, and the estimation error when the zenith angle prior information is shown in FIG. [Figure 11] 3 is a flowchart illustrating the processing of an estimation method using the estimation device according to the first embodiment of the present invention. [Figure 12] FIG. 10 is a diagram illustrating a configuration of an estimation device according to a second embodiment of the present invention. [Figure 13] FIG. 10 is a diagram showing a state in which a direct wave and a reflected wave of a transmission signal from a transmission antenna of a transmitting station are incident on a receiving antenna of a receiving device included in an estimation device according to a second embodiment of the present invention. [Figure 14] FIG. 1 is a diagram showing the zenith angle assumed by a conventional estimation method and the actual zenith angle. [Figure 15] FIG. 10 is a diagram showing an example in which the actual zenith angle is an angle other than 90 degrees. DETAILED DESCRIPTION OF THE INVENTION

[0018] (First embodiment) First, an estimation device and an estimation method according to a first embodiment of the present invention will be described with reference to the drawings.

[0019] 1, the estimation device 1 of this embodiment includes a receiving device 10, a signal recording device 13, an operation device 14, an array response output device 15, a signal processing device 20, and a display device 30. Each device is connected to each other by wireless communication or wired communication.

[0020] The receiving device 10 has a plurality of N antenna elements Rx_0 to Rx_N-1 that receive, as received signals, transmission signals transmitted from a transmission antenna of a transmitting station (not shown), and the same number of receiving units 11_0 to 11_N-1 as the plurality of N antenna elements Rx_0 to Rx_N-1. Note that hereinafter, the plurality of N antenna elements Rx_0 to Rx_N-1 will also be collectively referred to simply as "receiving antennas Rx."

[0021] Each of the antenna elements Rx_0 to Rx_N-1 is, for example, a planar antenna such as a microstrip antenna, and constitutes, for example, a Uniform Circular Array (UCA) antenna. That is, when the number N of the antenna elements Rx_0 to Rx_N-1 is 4, the four antenna elements Rx_0 to Rx_3 have directivities in the directions of 0°, 90°, 180°, and 270°, respectively, on the horizontal plane.

[0022] Each of the receiving units 11_0 to 11_N-1 performs receiving processes such as amplification, frequency conversion, and analog-to-digital conversion on the received signals (radio signals) received by the corresponding antenna elements Rx_0 to Rx_N-1. Note that the number of receiving units 11_0 to 11_N-1 may be less than the number of antenna elements Rx_0 to Rx_N-1, and in that case, it is sufficient that the configuration allows the antenna elements Rx_0 to Rx_N-1 to be switched and connected to each of the receiving units 11_0 to 11_N-1 using a switch or the like.

[0023] 2(a) and 2(b) are schematic diagrams showing an example configuration of the receiving device 10. In the example of Fig. 2(a) and 2(b), N=4, and four antenna elements Rx_0 to Rx_3 are provided at a height h on four side surfaces of a rectangular pillar 12.

[0024] As shown in Figure 2(b), the four antenna elements Rx_0 to Rx_3 are arranged so that the centers of adjacent antenna elements are spaced apart by 0.5λ in the horizontal direction, where λ is the wavelength of the millimeter-wave transmission signal transmitted from the transmitting antenna of the transmitting station.

[0025] The receiving device 10 may be installed at a measurement point on the ground, or may be mounted on a drone or the like and placed at a measurement point in the sky above the transmitting station.

[0026] The signal recording device 13 is a device equipped with a storage for recording data of the received signal that has been received and processed by the receiving device 10.

[0027] The operation device 14 is for accepting operation inputs by a user, and is configured, for example, as a touch panel equipped with a touch sensor for detecting a contact position by a touch operation on an input surface corresponding to the display screen of the display device 30. Alternatively, the operation device 14 may be configured to include an input device such as a keyboard or a mouse.

[0028] The operation device 14 receives the zenith angle advance information θ associated with the radio environment scenario selected by the user's operation input. prior is set in the array response output device 15 at the subsequent stage. That is, the user selects a radio environment scenario using the operation device 14, thereby indirectly setting the zenith angle prior information θ prior In this embodiment, the zenith angle prior information θ prior is an assumed value of the zenith angle of the arrival direction of a transmission signal from the transmission antenna of the transmitting station when the center position of the arrangement of the multiple antenna elements Rx_0 to Rx_N-1 is taken as the origin.

[0029] Examples of wireless environment scenarios include Dense Urban Macro, Dense Urban Micro, Rural, Indoor Hotspot, Dense Urban Macro (Drone), Dense Urban Micro (Drone), and Rural (Drone).

[0030] Dense Urban Macro is a wireless environment scenario that assumes an urban environment with a high user density and heavy traffic load, mainly consisting of pedestrians and vehicles, and the area covered by a single transmitter station is relatively wide, with a radius of about several hundred meters.

[0031] Dense Urban Micro is a wireless environment scenario that assumes an urban environment with a high user density and heavy traffic load, mainly consisting of pedestrians and vehicles, and the area covered by a single transmitter station is relatively small, with a radius of about several tens of meters.

[0032] Rural is a wireless environment scenario that covers a wider, continuous, wide area, supporting pedestrians, vehicles, and high-speed vehicle users.

[0033] Indoor Hotspot is a wireless environment scenario that is based on stationary users and pedestrians in an indoor isolated environment such as an office or shopping mall, with very high user density.

[0034] The above-mentioned Dense Urban Macro, Dense Urban Micro, Rural, and Indoor Hotspot are all wireless environment scenarios that assume the receiving device 10 is installed at a measurement point on the ground.

[0035] Dense Urban Macro (Drone) is a wireless environment scenario in which the receiving device 10 is mounted on a drone and placed at a measurement point in the sky in the above-described Dense Urban Macro.

[0036] Dense Urban Micro (Drone) is a wireless environment scenario in which the receiving device 10 is mounted on a drone and placed at a measurement point in the sky in the above-described Dense Urban Micro.

[0037] Rural (Drone) is a wireless environment scenario in which the receiving device 10 is mounted on a drone and placed at a measurement point in the sky.

[0038] Figure 3 shows the results of computer simulations (described later) for each of the above wireless environment scenarios, namely, Dense Urban Macro, Dense Urban Micro, and Indoor Hotspot, in order to determine the zenith angle a priori information θ that reduces the estimation error of the direction of arrival. prior For example, when the user selects Dense Urban Micro from the radio environment scenarios via the operation device 14, the array response output device 15 at the downstream side receives the zenith angle prior information θ prior is set to 70 deg.

[0039] The array response output device 15 calculates the zenith angle a priori information θ prior Array response vector a (bold) based on θprior (φ), where φ is the azimuth angle of the direction of arrival of the transmission signal when the center position of the arrangement of the multiple antenna elements Rx_0 to Rx_N-1 is taken as the origin. For example, the array response output device 15 receives zenith angle prior information θ prior The array response vectors are stored in a storage device that stores the array response vectors determined for each of the possible candidate values ​​of zenith angle θ selected by the operation device 14. prior Any method can be used to call the array response vector corresponding to

[0040]

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[0041] Array response vector a (bold)θprior Each element of (φ) is expressed by the following equation (2).

[0042]

number

[0043] where n is an integer between 0 and N-1. n (θ,φ) is the antenna gain [dBi] according to the zenith angle θ and the azimuth angle φ, and can be obtained by measuring the radiation patterns of the actual antenna elements Rx_0 to Rx_N-1 in advance. λ is the wavelength of the transmitted signal. r (bold) n is the position vector of each antenna element when the center position of the arrangement of multiple antenna elements Rx_0 to Rx_N-1 is the origin. d (bold) (θ, φ) is a unit vector that indicates the arrival direction of the transmitted signal when the center position of the arrangement of multiple antenna elements Rx_0 to Rx_N-1 is the origin, that is, the direction determined by the zenith angle θ and the azimuth angle φ, as shown in Fig. 4.

[0044] Position vector r (bold) of each antenna element Rx_0 to Rx_N-1 n In the case of a UCA antenna, is expressed by the following equation (3).

[0045]

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[0046] Here, R is the array radius, which is usually set so that the centers of adjacent antenna elements are spaced apart by 0.5λ in the horizontal direction.

[0047] The unit vector d (bold) (θ, φ) indicating the direction of arrival of the transmitted signal is expressed by the following equation (4).

[0048]

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[0049] The signal processing device 20 includes an angular spectrum estimation unit 21 and an arrival direction estimation unit 22. The signal processing device 20 is configured by a control device such as a computer including, for example, a central processing unit (CPU), a graphics processing unit (GPU), a field programmable gate array (FPGA), a read only memory (ROM), a random access memory (RAM), and a hard disk drive (HDD). For example, the signal processing device 20 can configure at least a part of the angular spectrum estimation unit 21 and the arrival direction estimation unit 22 in software form by executing a predetermined program using the CPU or the GPU.

[0050] The above program may be stored in advance in a ROM or HDD. Alternatively, the program may be provided or distributed in an installable or executable format recorded on a computer-readable recording medium such as a compact disc or DVD. Alternatively, the program may be stored in a computer connected to a network such as the Internet and provided or distributed by downloading via the network.

[0051] The angular spectrum estimation unit 21 estimates the array response vector a (bold) output from the array response output device 15. θprior The azimuth angle spectrum, which includes information on the azimuth angle of the arrival direction of the transmitted signal, is estimated from (φ) and the vector data of the received signal (hereinafter simply referred to as the "received signal vector") y (bold)(t) that has been received and processed by the receiving device 10 and recorded in the signal recording device 13.

[0052] The received signal vector y (bold)(t) is expressed by the time waveform data y of the received signal at the antenna element Rx_n as shown in the following equation (5). n (t) is a vector whose elements are n, where n is an integer between 0 and N-1.

[0053]

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[0054] For example, the angular spectrum estimator 21 may estimate the azimuth angular spectrum of the transmission signal using a direction of arrival estimation algorithm such as the well-known beamformer method, MUSIC method, or FISTA (Fast Iterative Shrinkage-Thresholding Algorithm).

[0055] Hereinafter, the process of estimating the azimuth angle spectrum when the angle spectrum estimator 21 uses FISTA, which is one of the compressed sensing algorithms, will be described.

[0056] As shown in Figure 5, the angular space is divided into M small regions (bins), and the transmitted signal is located in the mth bin (azimuth angle φ m Consider a situation where the transmitted signal passes through the zenith angle information θ prior Assuming that the signal arrives from the direction of , the received signal vector y (bold)(t) is given by the following equation (6).

[0057]

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[0058] Here, A (bold) θprior is an array response matrix consisting of M columns, where each column corresponds to the azimuth angle φ from 0 to M-1. m Array response vector a (bold) corresponding to θprior (φ m ) x(bold)(t) is the transmitted signal vector, and its element x m (t) is the time waveform data of the transmitted signal arriving via the m-th bin #m. z (bold)(t) is a noise vector, and its element z0(t) is the time waveform data of the noise.

[0059] Normally, the transmitted signal is considered to be incident on only a portion of the M bins, so the transmitted signal vector x(bold)(t) is expected to be a sparse vector with many zero elements. Therefore, the angular spectrum estimator 21 can estimate the transmitted signal vector x(bold)(t) by applying compressed sensing such as FISTA to the received signal vector y(bold)(t).

[0060] Furthermore, the angular spectrum estimation unit 21 calculates the power value of the transmission signal from the estimated transmission signal vector x (bold)(t) by multiplying it by the azimuth angle φ m 6 is a graph schematically showing the azimuth angle spectrum S(φ) estimated by the angle spectrum estimator 21 when the number of incoming waves of the transmission signal is two.

[0061] The arrival direction estimation unit 22 detects a peak contained in the azimuth angle spectrum S(φ) estimated by the angle spectrum estimation unit 21, and estimates the azimuth angle of the detected peak as the azimuth angle of the arrival direction of the transmission signal.

[0062] The arrival direction estimation unit 22 estimates the m-th transmitted signal x m When the peak power value of (t) is equal to or greater than the specified value, the azimuth angle of the arrival direction of the transmitted signal is φ m 6, if the specified value is −40 dB, the arrival direction estimation unit 22 estimates 162 degrees and 273 degrees as the azimuth angle φ of the arrival direction of the transmitted signal, and if the specified value is −30 dB, the arrival direction estimation unit 22 estimates 162 degrees as the azimuth angle φ of the arrival direction of the transmitted signal. This specified value can be set to an arbitrary value, for example, by a user operating the operation device 14.

[0063] The display device 30 is configured with a display device such as an LCD (Liquid Crystal Display), a CRT (Cathode Ray Tube), etc. In response to a display control signal from the signal processing device 20, the display device 30 displays the azimuth angle spectrum S(φ) estimated by the angle spectrum estimator 21 and the azimuth angle φ of the peak of the azimuth angle spectrum S(φ) estimated by the direction-of-arrival estimator 22, as shown in Fig. 6, for example.

[0064] The effects of the estimation device 1 according to this embodiment will be confirmed by computer simulation below. In this computer simulation, the Dense Urban Macro, Dense Urban Micro, and Indoor Hotspot described in Report ITU-R M.2412-0 are used as radio environment scenarios. In addition, in this computer simulation, a carrier frequency of 28.0 GHz is assumed, and FISTA is used as the direction-of-arrival estimation algorithm.

[0065] Figure 7 is a graph showing the antenna element radiation pattern in the horizontal plane of the UCA antenna consisting of four antenna elements #0 to #3 used as the receiving antenna Rx in this computer simulation. The four antenna elements #0 to #3 have directivity in the directions of 0°, 90°, 180°, and 270° in the horizontal plane, respectively. Based on Report ITU-R M.2412-0, the maximum directional gain of each of antenna elements #0 to #3 is 5 dBi, and the beamwidth in both the vertical and horizontal directions is 90°.

[0066] Figure 8 is a table showing the parameters used in this computer simulation. "Cell radius" represents the horizontal distance between the transmitting antenna of the transmitting station and the center position of the four antenna elements #0 to #3. "Tx antenna height" represents the height of the transmitting antenna of the transmitting station. "Rx antenna height" represents the height of the four antenna elements #0 to #3.

[0067] Therefore, the actual zenith angle θ of the transmitting antenna as viewed from the center position of the four antenna elements #0 to #3 at the cell edge is 80.0 deg for Dense Urban Macro, 73.6 deg for Dense Urban Micro, and 84.3 deg for Indoor Hotspot.

[0068] In this computer simulation, a known received signal vector y(bold)(t) based on a transmitted signal from a transmitting antenna at a known position is prepared for each of the three wireless environment scenarios. That is, this computer simulation simulates a process in which the known received signal vector y(bold)(t) is input to the signal processing device 20 of the estimation device 1 of this embodiment, and the signal processing device 20 estimates the azimuth angle of the known arrival direction of the transmitted signal.

[0069] Figure 9 shows the zenith angle prior information θ prior 9 is a graph showing the root mean squared error (RMSE) between the azimuth angle estimated by the computer simulation and the actual known azimuth angle for each radio environment scenario when the azimuth angle is 10°, 20°, 30°, 40°, 50°, 60°, 70°, 80°, and 90°. That is, Fig. 9 shows the estimation error of the azimuth angle obtained by the computer simulation. This RMSE is calculated by dividing the total number of trials of the computer simulation by T and the actual known azimuth angle in the tth trial by φ. t , the azimuth angle estimated in the t-th trial is φ^ t Then, it is calculated according to the following formula (7).

[0070]

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[0071] According to the graph in Fig. 9, in the outdoor scenario Dense Urban Macro / Micro, the zenith angle prior information θ priorOn the other hand, in the indoor scenario, Indoor Hotspot, the RMSE is best when the zenith angle prior information θ prior It can be seen that the RMSE is best when the zenith angle prior information θ prior In this computer simulation, the zenith angle prior information θ that gives the best RMSE is prior It gives.

[0072] Fig. 10 shows the estimation error of the azimuth angle shown in Fig. 9, when the zenith angle prior information θ prior The estimation error when the zenith angle is 90 deg and the RMSE shown in Fig. 3 is the best when the zenith angle is θ prior , and the estimation error for each of the above-mentioned radio environment scenarios. prior The estimation error when θ is 90° corresponds to the estimation error of the conventional method using the array response vector when the zenith angle of the arrival direction of the transmitted signal is assumed to be 90°. prior The estimation error when is the value shown in FIG. 3 corresponds to the estimation error of the estimation method of the present invention.

[0073] In environments such as dense urban macro and dense urban micro, the difference between the height of the transmitting antenna and the height of the receiving antenna Rx of the receiving device 10 is relatively large compared to the horizontal distance between the transmitting antenna of the transmitting station and the receiving antenna Rx, so the zenith angle of the arrival direction of the transmitted signal tends to be smaller than 90 degrees. From the results shown in Fig. 10, it was confirmed that the estimation device 1 of this embodiment can improve the estimation accuracy of the zenith angle of the arrival direction of the transmitted signal in an environment where the zenith angle of the arrival direction of the transmitted signal is smaller than 90 degrees.

[0074] An example of the processing of an estimation method using the estimation device 1 according to this embodiment will be described below with reference to the flowchart in Fig. 11. Note that descriptions that overlap with the description of the configuration of the estimation device 1 described above will be omitted as appropriate.

[0075] First, the receiving device 10 is placed at a measurement point on the ground or in the air (step S1).

[0076] Next, a wireless environment scenario is selected by the user through an operation input to the operation device 14 (step S2).

[0077] Next, the receiving device 10 receives the transmission signals transmitted from the transmitting antenna of the transmitting station as received signals by the plurality of antenna elements Rx_0 to Rx_N-1, and performs receiving processes such as amplification, frequency conversion, and analog-to-digital conversion on the received signals (step S3).

[0078] Next, the signal recording device 13 records the data of the received signal that has been subjected to reception processing in step S3 (step S4).

[0079] Next, the array response output device 15 calculates the zenith angle a priori information θ associated with the radio environment scenario selected in step S2. prior Array response vector a (bold) based on θprior (φ) is output (step S5).

[0080] Next, the angular spectrum estimation unit 21 calculates the array response vector a (bold) output from the array response output device 15. θprior (φ) and the data of the received signal recorded in the signal recording device 13, the azimuth angle spectrum S(φ) of the transmitted signal is estimated (angle spectrum estimation step S6).

[0081] Next, the arrival direction estimating unit 22 estimates the azimuth angle of each peak included in the azimuth angle spectrum S(φ) estimated in the angular spectrum estimating step S6 as the azimuth angle of the arrival direction of the transmitted signal (step S7).

[0082] Next, the display device 30 displays the azimuth angle spectrum S(φ) estimated in the angular spectrum estimation step S6 and the azimuth angle of the peak of the azimuth angle spectrum S(φ) estimated in step S7 (step S8).

[0083] As described above, the estimation device 1 according to this embodiment calculates the zenith angle a priori information θ , which is an estimated value of the zenith angle of the arrival direction of a transmission signal, in accordance with the radio environment scenario selected by the user. prior Furthermore, the estimation device 1 according to this embodiment can switch between the selected zenith angle prior information θ prior Array response vector a (bold) based on θprior (φ) is used to estimate the azimuth angle of the direction of arrival of the transmitted signal.

[0084] As a result, the estimation device 1 according to this embodiment can accurately estimate the azimuth angle of the arrival direction of a transmitted signal even in an environment where the antenna heights of the transmitter and receiver are different, i.e., even if the zenith angle of the arrival direction of the transmitted signal is an angle other than 90 degrees.

[0085] Furthermore, the estimation device 1 according to this embodiment can accurately estimate the azimuth angle of the arrival direction of a transmitted signal even when the position of the transmitting antenna of the transmitting station is unknown, by allowing the user to select an appropriate radio environment scenario.

[0086] (Second embodiment) Next, an estimation device 2 according to a second embodiment of the present invention will be described with reference to the drawings. Note that the same components as those in the first embodiment are denoted by the same reference numerals and their description will be omitted as appropriate, and differences from the first embodiment will be mainly described.

[0087] The estimation device 1 of the first embodiment receives the zenith angle a priori information θ associated with the radio environment scenario by the user selecting the radio environment scenario via the operation device 14. prior The configuration was to select

[0088] As shown in FIG. 12, the estimation device 2 of the second embodiment uses the zenith angle prior information θ prior The elevation angle measurement device 40 sets the above to the array response output device 15.

[0089] The elevation angle measurement device 40 is, for example, a laser or a level with a finder, and measures the elevation angle of the transmitting antenna of the transmitting station as seen from the center position of the plurality of antenna elements Rx_0 to Rx_N-1, i.e., the elevation angle of the transmitting antenna of the transmitting station located on the line of sight from the center position of the plurality of antenna elements Rx_0 to Rx_N-1. Furthermore, the elevation angle measurement device 40 calculates the measured elevation angle value based on the zenith angle prior information θ prior and set it in the array response output device 15 as:

[0090] In this embodiment, the array response output device 15 receives the zenith angle prior information θ set by the elevation angle measurement device 40. prior Array response vector a (bold) based on θprior The subsequent processing of the estimation device 2 of this embodiment is the same as that of the estimation device 1 of the first embodiment.

[0091] Furthermore, as shown in Fig. 13, the estimation device 2 of this embodiment can estimate the arrival direction of not only the direct wave but also the reflected wave in a situation where the direct wave (solid arrow) and the reflected wave (dashed arrow) of the transmission signal from the transmitting antenna Tx of the transmitting station are incident on the receiving antenna Rx. This is because the direct wave and the reflected wave from the same transmitting antenna Tx are considered to have a high correlation in their arrival directions, and therefore the same zenith angle a priori information θ is used for the direct wave and the reflected wave. prior Array response vector a (bold) based on θprior This is because (φ) can be used.

[0092] As described above, the estimation device 2 according to this embodiment calculates the elevation angle of the transmitting antenna Tx measured by the elevation angle measurement device 40 based on the zenith angle prior information θ prior It has come to be used as such.

[0093] As a result, the estimation device 2 according to this embodiment can accurately estimate the azimuth angles of the directions of arrival of the direct wave and reflected wave of the transmission signal, even in a so-called multipath situation in which both the direct wave and the reflected wave of the transmission signal are incident on the receiving antenna Rx. [Explanation of symbols]

[0094] 1,2 Estimation device 10 Receiving device 11_0~11_N-1 Receiver 13 Signal recording device 14 Operating device 15 Array response output device 20 Signal Processing Device 21 Angular spectrum estimation unit 22 Direction of Arrival Estimator 30 Display device 40 Elevation angle measuring device Tx Transmitting Antenna Rx receiving antenna Rx_0~Rx_N-1 antenna elements

Claims

1. a receiving device (10) having a plurality of antenna elements (Rx_0 to Rx_N-1) for receiving a transmission signal transmitted from a transmission antenna of a transmitting station as a reception signal; a signal recording device (13) for recording data of the received signal; an array response output device (15) that outputs zenith angle prior information θ prior that is an assumed value of the zenith angle of the arrival direction of the transmission signal and an array response vector based on the radiation patterns of the plurality of antenna elements; an angular spectrum estimator (21) that estimates an azimuth angular spectrum of the transmission signal from the array response vector and data of the reception signal; an arrival direction estimation unit (22) that estimates the azimuth angle of each peak included in the azimuth angle spectrum estimated by the angle spectrum estimation unit as the azimuth angle φ of the arrival direction of the transmission signal, The array response vector is expressed by the following equation (1): Each element of the array response vector is expressed by the following equation (2): The plurality of antenna elements are uniform circular array antennas, and each of the antenna elements has directivity in a different direction from each other; The estimation device, wherein the angular spectrum estimation unit uses FISTA, which is a compressed sensing algorithm. [Equation 1] [Equation 2] In equation (2), G n (θ prior , φ) is the antenna gain [dBi] according to the zenith angle prior information θ prior and the azimuth angle φ, and is obtained from the radiation pattern. r n is a position vector of each of the antenna elements when the center position of the arrangement of the plurality of antenna elements is the origin, and d(θ prior , φ) is a unit vector indicating the arrival direction of the transmission signal when the center position of the arrangement of the plurality of antenna elements is the origin.

2. further comprising an elevation angle measuring device (40) for measuring an elevation angle of the transmitting antenna as viewed from a central position of the plurality of antenna elements, 2. The estimation device according to claim 1, wherein the zenith angle prior information is a value of the elevation angle measured by the elevation angle measurement device.

3. 3. The estimation device according to claim 2, wherein the elevation angle measurement device is a level with a laser or a finder, and measures the elevation angle of the transmitting antenna of the transmitting station located on a line of sight from the center position of the plurality of antenna elements.

4. The wireless communication system further includes an operation device (14) for selecting a wireless environment scenario through an operation input by a user, The estimation device according to claim 1 , wherein the operation device selects the zenith angle prior information by selecting the radio environment scenario.

5. When the operation device selects the radio environment scenario, the operation device sets the zenith angle advance information that reduces an estimation error in the direction of arrival in the array response output device (15); 5. The estimation device according to claim 4, wherein the estimation error is a root mean squared error (RMSE) between an azimuth angle estimated by computer simulation and an actual known azimuth angle.

6. a step (S3) of receiving a transmission signal transmitted from a transmission antenna of the transmitting station as a reception signal by a plurality of antenna elements (Rx_0 to Rx_N-1); a step (S4) of recording data of the received signal; a step (S5) of outputting zenith angle prior information θ prior which is an estimated value of the zenith angle of the arrival direction of the transmission signal and an array response vector based on the radiation patterns of the plurality of antenna elements; an angular spectrum estimation step (S6) of estimating an azimuth angular spectrum of the transmission signal from the array response vector and data of the reception signal; a step (S7) of estimating the azimuth angle of each peak included in the azimuth angle spectrum estimated in the angular spectrum estimation step as the azimuth angle φ of the direction of arrival of the transmission signal, The array response vector is expressed by the following equation (1): Each element of the array response vector is expressed by the following equation (2): The plurality of antenna elements are uniform circular array antennas, and each of the antenna elements has directivity in a different direction from each other; The estimation method is characterized in that the angular spectrum estimation step uses FISTA, which is a compressed sensing algorithm. [Equation 3] [Equation 4] In equation (2), G n (θ prior , φ) is the antenna gain [dBi] according to the zenith angle prior information θ prior and the azimuth angle φ, and is obtained from the radiation pattern. r n is a position vector of each of the antenna elements when the center position of the arrangement of the plurality of antenna elements is the origin, and d(θ prior , φ) is a unit vector indicating the arrival direction of the transmission signal when the center position of the arrangement of the plurality of antenna elements is the origin.

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