Method, device, and program for creating radio wave propagation model

Abstract

A method for creating a radio wave propagation model (M2) for performing radio wave propagation analysis of a target structure, said method comprising: an acquisition step (S1) of acquiring a three-dimensional model (M1) of the target structure; a determination step (S2) of determining RCS in the three-dimensional model (M1); and a radio wave propagation model creation step (S3) of creating a radio wave propagation model (M2) by removing a portion where RCS is equal to or less than a threshold value from the three-dimensional model (M1).

Description

Method, apparatus, and program for creating a radio wave propagation model

[0001] The present invention relates to a method, apparatus, and program for creating a radio wave propagation model.

[0002] In order to prepare an environment for performing wireless communication, there is a method of making a design plan in advance as reported. For example, in Non-Patent Document 1, it is disclosed that the communication environment when a transmission point (access point) is installed at the center of the ceiling of a factory is analyzed by the ray tracing method. In the ray tracing method, radio wave propagation considering buildings, terrain, etc. can be simulated by analyzing a three-dimensional model of the target structure using analysis software (for example, Non-Patent Document 2).

[0003] "Wireless Environment Evaluation in Factory", Structural Planning Research Institute, Internet <URL: https: / / network2.kke.co.jp / consulting_samples / factory> "Radio Wave Propagation Analysis Tool Wireless InSite", Structural Planning Research Institute, Internet <URL: https: / / network2.kke.co.jp / wireless-products / wireless-insite> "Comparison between Ray Tracing Method and FDTD Method (Radio Wave Propagation in Tunnel)", Structural Planning Research Institute, Internet <URL: https: / / network2.kke.co.jp / column / tunnel-propergation> "RCS01 Compact Range Near Field to Far Field Conversion RCS (Radar Cross Section) Measurement System - 01", Keycom Co., Ltd., Internet <URL: https: / / keycom.co.jp / jproducts / rcs / rcs01 / page.html> "Analysis of Radar Cross Section (RCS) in Millimeter Wave Band", Structural Planning Research Institute, Internet <URL: https: / / network2.kke.co.jp / consulting_samples / rcs>

[0004] However, since various objects exist in a factory, room, etc., the three-dimensional model of the target structure tends to be overly detailed, and there is a problem that the analysis of radio wave propagation takes time.

[0005] This invention has been made in view of the above problems, and aims to shorten the analysis time while ensuring the accuracy of the radio wave propagation analysis.

[0006] To solve the above problems, the present invention includes the following embodiments. 1. A method for creating a radio wave propagation model for performing radio wave propagation analysis of a target structure, comprising: an acquisition step of acquiring a three-dimensional model of the target structure; a determination step of determining the RCS in the three-dimensional model; and a radio wave propagation model creation step of creating a radio wave propagation model by removing portions of the three-dimensional model in which the RCS is below a threshold. 2. A method according to 1, wherein the determination step comprises: a decomposition step of decomposing the three-dimensional model into individual objects; a calculation step of calculating the RCS of each of the objects; and the radio wave propagation model creation step comprises: an identification step of identifying small objects among the objects in which the RCS is below a threshold; and a removal step of removing the small objects from the three-dimensional model. 3. Apparatus for creating a radio wave propagation model for performing radio wave propagation analysis of a target structure, comprising: acquisition unit for acquiring a three-dimensional model of the target structure; determination unit for determining the RCS in the three-dimensional model; and radio wave propagation model creation unit for creating a radio wave propagation model by removing portions of the three-dimensional model where the RCS is below a threshold. Item 4. Apparatus according to Item 3, wherein the determination unit comprises: decomposition unit for decomposing the three-dimensional model into individual objects; calculation unit for calculating the RCS of each of the objects; and the radio wave propagation model creation unit comprises: identification unit for identifying small objects among the objects whose RCS is below a threshold; and removal unit for removing the small objects from the three-dimensional model. Item 5. A program for creating a radio wave propagation model for performing radio wave propagation analysis of a target structure, the program causing a computer to perform the following steps: an acquisition step to acquire a three-dimensional model of the target structure; a determination step to determine the RCS in the three-dimensional model; and a radio wave propagation model creation step to create a radio wave propagation model by removing the portion of the three-dimensional model in which the RCS is below a threshold.Item 6. A program as described in Item 5, wherein the determination step comprises: a decomposition step of decomposing the three-dimensional model into individual objects; and a calculation step of calculating the RCS of each of the objects; and the radio wave propagation model creation step comprises: a identification step of identifying small objects among the objects whose RCS is below a threshold; and a removal step of removing the small objects from the three-dimensional model.

[0007] According to the present invention, it is possible to shorten the analysis time while ensuring the accuracy of the radio wave propagation analysis.

[0008] This is a block diagram showing the configuration of a radio wave propagation analysis system 1 according to one embodiment of the present invention. This is a flowchart showing the processing procedure of a method according to one embodiment of the present invention. This is a flowchart showing the processing procedure of the determination step. This is a flowchart showing the processing procedure of the radio wave propagation model creation step. (A) and (B) are examples of three-dimensional models. (A) to (J) are examples of decomposed objects. This is an example of a radio wave propagation model. This is a diagram showing the three-dimensional model in Example 1. This is a diagram showing the radio wave propagation model in Example 1. This is a diagram showing the three-dimensional model in Example 2. This is a diagram showing the radio wave propagation model in Example 2. This is a diagram showing the radio wave propagation model in Example 2.

[0009] Embodiments of the present invention will be described below with reference to the accompanying drawings.

[0010] (System Configuration) Figure 1 is a block diagram showing the configuration of a radio wave propagation analysis system 1 according to one embodiment of the present invention. The radio wave propagation analysis system 1 is a system for analyzing the radio wave propagation environment of a target structure and includes a 3D scanner 2 and an information processing device 3. The target structure is not particularly limited as long as it is a structure, but in this embodiment the target structure is a building (room).

[0011] The 3D scanner 2 has the function of generating point cloud data that shows the three-dimensional shape of a target structure by irradiating the target structure with laser light and measuring its surface shape with a sensor. Furthermore, the 3D scanner 2 can convert the point cloud data into 3D CAD data, and the 3D CAD data is transferred to the information processing device 3.

[0012] The information processing device 3 can be configured as a general-purpose computer. The information processing device 3 includes, as a hardware configuration, a processor such as a CPU or GPU (not shown), a main memory such as DRAM or SRAM (not shown), and an auxiliary storage device 30 such as an HDD or SSD. The auxiliary storage device 30 stores the 3D model M1, a program P, an RCS calculation database DB, etc. In this embodiment, the 3D model M1 is 3D CAD data transferred from the 3D scanner 2.

[0013] The auxiliary storage device 30 may be externally connected to the information processing device 3. Furthermore, the information processing device 3 may be located on the cloud.

[0014] The information processing device 3 has, as functional blocks, an acquisition unit 31, a determination unit 32, a radio wave propagation model creation unit 33, and an analysis unit 34. Furthermore, the determination unit 32 has a decomposition unit 321 and a calculation unit 322, and the radio wave propagation model creation unit 33 has a identification unit 331 and a removal unit 332. These functional blocks may be implemented in hardware by logic circuits formed on an integrated circuit, but in this embodiment, they are implemented in software by the processor of the information processing device 3 reading the program P from the auxiliary storage device 30 to the main storage device and executing it. The program P may be downloaded to the information processing device 3 via a communication network such as the Internet, or the program P may be recorded on a computer-readable non-temporary recording medium such as a CD-ROM or SD card and transferred to the information processing device 3 via the recording medium.

[0015] (Processing Procedure) The functions of the information processing device 3 will be explained based on Figure 2. Figure 2 is a flowchart showing the processing procedure of the method according to this embodiment.

[0016] In step S1 (acquisition step), the acquisition unit 31 acquires the 3D model M1 by reading it from the auxiliary storage device 30. Alternatively, the acquisition unit 31 may acquire the 3D model M1 by receiving it directly from the 3D scanner 2.

[0017] In step S2 (determination step), the determination unit 32 determines the RCS in the 3D model M1. RCS (radar cross-section) is an index that indicates the size of the reflected area of ​​radio waves, calculated from the magnitude (electric field strength) of the reflected radio waves when radio waves of a certain frequency are reflected from an object. In other words, RCS is an electromagnetic definition that indicates how large an object appears to be when viewed from the perspective of radio waves. Therefore, the larger the RCS, the greater the reflection and the larger the object appears to be from the perspective of radio waves.

[0018] In step S3 (radio wave propagation model creation step), the radio wave propagation model creation unit 33 creates the radio wave propagation model M2 by removing the portion of the 3D model M1 where the RCS is below a threshold. The radio wave propagation model M2 is stored in the auxiliary storage device 30.

[0019] In step S4, the analysis unit 34 analyzes the radio wave propagation environment of the target structure based on the radio wave propagation model M2. The analysis method is not particularly limited as long as it is a known method, and for example, the ray tracing method or the FDTD method (Non-Patent Literature 3) can be used.

[0020] The radio wave propagation model M2 is obtained by removing the portion of the 3D model M1 in which the RCS is below a threshold. As a result, the radio wave propagation model M2 simplifies the excessive detail of the 3D model M1, allowing the analysis unit 34 to perform the analysis with less computation than when analyzing the 3D model M1. Furthermore, since the portion of the RCS below the threshold is an object of negligible size relative to radio waves, the impact of removing this portion on the analysis accuracy is small. Therefore, the analysis time can be shortened while ensuring the accuracy of the radio wave propagation analysis.

[0021] Steps S2 and S3 will be explained in more detail. Figure 3 is a flowchart showing the processing procedure for step S2, and Figure 4 is a flowchart showing the processing procedure for step S3.

[0022] As shown in Figure 3, step S2 includes steps S21 and S22.

[0023] In step S21 (decomposition step), the decomposition unit 321 decomposes the 3D model M1 into individual objects. As a specific example, suppose the 3D model M1 is 3D CAD data of a room as shown in Figures 5(A) and (B), and is composed of 10 objects T1 to T10. Objects T1 to T6 are a light fixture, an air purifier, a television, a table, an air conditioner, and a chest of drawers, respectively. Objects T7 and T8 are window panes, object T9 is a glass panel for the balcony, and object T10 is a partition that divides the entire room. The decomposition unit 321 decomposes the 3D model M1 into objects T1 to T10 as shown in Figures 6(A) to (J).

[0024] In step S22 (calculation step), the calculation unit 322 calculates the RCS for each of the objects T1 to T10. The method for calculating the RCS is not particularly limited, but in this embodiment, the calculation unit 322 calculates the RCS by referring to the RCS calculation database DB.

[0025] The RCS calculation database DB includes the type of object (air conditioner, television, chest of drawers, etc.), the size of each object, the RCS of each object, and the RCS proportionality constant with respect to size. The RCS calculation database DB can be created by first identifying the RCS of each object through actual measurement or simulation. A method for identifying the RCS by actual measurement is disclosed, for example, in Non-Patent Document 4, and a method for identifying the RCS by simulation is disclosed, for example, in Non-Patent Document 5.

[0026] The calculation unit 322 can determine the type and size of each object T1 to T10 using, for example, a machine learning-based discrimination model, and then query the RCS calculation database DB to calculate the RCS for each object T1 to T10. Alternatively, instead of using a discrimination model, the user may determine the type and size of each object T1 to T10.

[0027] This concludes step S2.

[0028] As shown in Figure 4, step S3 comprises steps S31 to S33.

[0029] In step S31 (identification step), the identification unit 331 determines whether there are any small objects among the objects T1 to T10 whose RCS is below a threshold. The threshold can be set appropriately considering the complexity of the target structure, the required design accuracy of wireless communication, the length of economically reasonable analysis time, etc. In this embodiment, four objects T4, T6 to T9 are identified as small objects.

[0030] If there are small objects (YES in step S32), the process proceeds to step S33 (removal step), where the removal unit 332 removes the small objects from the 3D model M1. As a result, a radio wave propagation model M2 consisting of objects T1 to T3, T5, and T10 is created, as shown in Figure 7.

[0031] The radio wave propagation model M2 is a simplified version of the 3D model M1 shown in Figures 5(A) and (B), as it removes objects T4, T6-T9, which are below the threshold RCS. In this case, the number of objects is reduced from 10 to 6, thus reducing the computational load required for radio wave propagation analysis. ６ C ２ / １０ C ２ This can reduce the number of objects by approximately one-third. Furthermore, since the removed objects T4, T6-T9 are small objects from the perspective of radio waves, their impact on analysis accuracy is minimal. Therefore, it is possible to shorten the analysis time while maintaining the accuracy of radio wave propagation analysis.

[0032] (Additional Notes) Although embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications are possible without departing from the spirit of the invention.

[0033] For example, in the above embodiment, the 3D model M1 was 3D CAD data, but it is not particularly limited as long as it is data of a target structure that can be subjected to radio wave propagation analysis, and the 3D model M1 may be, for example, point cloud data. In this case, the 3D scanner 2 may transfer the point cloud data to the information processing device 3 without converting it to 3D CAD data.

[0034] In the embodiment, the effect of reducing computation time was verified by simulating the analysis time of radio wave propagation for a 3D model of the target structure and a radio wave propagation model obtained by removing the portion of the 3D model from which the RCS is below a threshold. However, the present invention is not limited to the embodiments described below.

[0035] (Example 1) Figure 8 shows the 3D model M11 in Example 1. The 3D model M11 consists of an object T11 that defines space, three large objects T12a to T12c, two medium objects T13a and T13b, and five small objects T14a to T14e. Object T11 is a rectangular parallelepiped, the medium objects T13a and T13b are cubes, and the large objects T12a to T12c and the small objects T14a to T14e are spheres. The center coordinates, length (m), or radius (m) of each object are shown in Table 1.

[0036]

[0037] Object T11 has an internal space, while the area outside object T11 and objects T12 to T14 other than object T11 are tangible objects made of perfect conductors (PEC). When a dipole antenna A is placed at coordinates (0.5, 2, 1.5), the RCS for large objects T12a to T12c is 0.8043 (m ２ ) and the middle objects T13a and T13b are each 0.1712 (m ２ ) and the small objects T14a to T14e are each 0.034 (m２ That is, the RCS in this embodiment is defined as bistatic RCS, where the measurement point is set to be deviated by 90 degrees from the incident angle, rather than the so-called monostatic RCS when facing directly.

[0038] Fig. 9 shows the radio wave propagation model M12 in Embodiment 1. The radio wave propagation model M12 is obtained by removing small objects T14a to T14e from the three-dimensional model M11.

[0039] In this embodiment, using a computing device equipped with a CPU (Xeon Platinum 8259CL) and a RAM (64 GB) manufactured by Intel, radio wave propagation analysis simulations were performed on the three-dimensional model M11 and the radio wave propagation model M12. As a result, the analysis time of the three-dimensional model M11 was 2 hours 39 minutes 20 seconds, while the analysis time of the radio wave propagation model M12 was 1 hour 33 minutes 40 seconds.

[0040] Thus, in this embodiment, it was found that by simply removing small objects T14a to T14e that have an extremely small impact on the analysis accuracy, the computation amount can be reduced by approximately 41%.

[0041] (Embodiment 2) Fig. 10 shows the three-dimensional model M13 in Embodiment 2, Fig. 11 shows the radio wave propagation model M14 in Embodiment 2, and Fig. 12 shows the radio wave propagation model M15 in Embodiment 2. The three-dimensional model M13 is obtained by removing the large object T12b from the three-dimensional model M11 shown in Fig. 8. The radio wave propagation model M14 is obtained by removing small objects T14a to T14e from the three-dimensional model M13, and the radio wave propagation model M15 is obtained by removing medium objects T13a and T13b from the radio wave propagation model M14.

[0042] In this embodiment, using the same computing device as in Embodiment 1, radio wave propagation analysis simulations were performed on the three-dimensional model M13, the radio wave propagation model M14, and the radio wave propagation model M15. As a result, the analysis time of the three-dimensional model M13 was 2 hours 0 minutes 26 seconds, while the analysis time of the radio wave propagation model M14 was 51 minutes 49 seconds, and the analysis time of the radio wave propagation model M15 was 17 minutes 35 seconds.

[0043] Thus, in this embodiment, it was found that the computational load can be reduced by approximately 57% simply by removing small objects T14a to T14e, which have very little impact on analysis accuracy. Furthermore, it was found that if the requirement for analysis accuracy is not so high, the computational load can be reduced by approximately 85% by removing medium objects T13a and T13b.

[0044] 1 Radio wave propagation analysis system 2 3D scanner 3 Information processing device (device) 30 Auxiliary storage device 31 Acquisition unit 32 Judgment unit 321 Decomposition unit 322 Calculation unit 33 Radio wave propagation model creation unit 331 Identification unit 332 Removal unit 34 Analysis unit DB RCS calculation database M1 3D model M2 Radio wave propagation model M11 3D model M12 Radio wave propagation model M13 3D model M14 Radio wave propagation model M15 Radio wave propagation model P Program T1-T11 Objects T12a-T12c Large objects T13a, T13b Medium objects T14a-T14e Small objects

Claims

1. A method for creating a radio wave propagation model for performing radio wave propagation analysis of a target structure, comprising: an acquisition step of acquiring a three-dimensional model of the target structure; a determination step of determining the RCS in the three-dimensional model; and a radio wave propagation model creation step of creating a radio wave propagation model by removing the portion of the three-dimensional model in which the RCS is below a threshold.

2. A method according to claim 1, wherein the determination step comprises: a decomposition step of decomposing the three-dimensional model into individual objects; and a calculation step of calculating the RCS of each of the objects; and the radio wave propagation model creation step comprises: a identification step of identifying small objects among the objects whose RCS is below a threshold; and a removal step of removing the small objects from the three-dimensional model.

3. An apparatus for creating a radio wave propagation model for performing radio wave propagation analysis of a target structure, comprising: an acquisition unit for acquiring a three-dimensional model of the target structure; a determination unit for determining the RCS in the three-dimensional model; and a radio wave propagation model creation unit for creating a radio wave propagation model by removing the portion of the three-dimensional model in which the RCS is below a threshold.

4. The apparatus according to claim 3, wherein the determination unit comprises: a decomposition unit for decomposing the three-dimensional model into individual objects; and a calculation unit for calculating the RCS of each of the objects; and the radio wave propagation model creation unit comprises: a identification unit for identifying small objects among the objects whose RCS is below a threshold; and a removal unit for removing the small objects from the three-dimensional model.

5. A program for creating a radio wave propagation model for performing radio wave propagation analysis of a target structure, the program causing a computer to perform the following steps: an acquisition step to acquire a three-dimensional model of the target structure; a determination step to determine the RCS in the three-dimensional model; and a radio wave propagation model creation step to create a radio wave propagation model by removing the portion of the three-dimensional model in which the RCS is below a threshold.

6. A program according to claim 5, wherein the determination step comprises: a decomposition step of decomposing the three-dimensional model into individual objects; and a calculation step of calculating the RCS of each of the objects; and the radio wave propagation model creation step comprises: a identification step of identifying small objects among the objects whose RCS is below a threshold; and a removal step of removing the small objects from the three-dimensional model.

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