Information processing system, radio wave propagation simulation method, and program

Abstract

The present invention provides an information processing system including: an acquisition unit that divides a target area into multiple meshes with a predetermined size and obtains mesh data representing an environment of the target area with height information of each of the multiple meshes; a first ray tracing unit that obtains, on the basis of the mesh data, two-dimensional ray traces from a transmission point at which radio waves are transmitted to a reception point at which the radio waves are received; a second ray tracing unit that obtains three-dimensional ray traces corresponding to the two-dimensional ray traces on the basis of the mesh data and the height information of the transmission point and the reception point; and a radio field strength calculation unit that calculates the strength of the radio waves at the reception point using one or more of the three-dimensional ray traces obtained by the second ray tracing unit.

Description

[Technical field]

[0001] The present invention relates to an information processing system, a radio wave propagation simulation method, and a program. [Background technology]

[0002] Ray tracing is a method for simulating radio wave propagation used in area evaluation of wireless communication systems, etc. In ray tracing, radio waves (rays) transmitted from a transmitting point are reflected or diffracted by structures along the way, and the trajectory of each ray is traced to arrive at a receiving point, and the power of all rays that reach the receiving point is added up to estimate the strength of the radio waves at the receiving point.

[0003] Also, an indoor wireless communication system is known that uses ray tracing to simulate the propagation characteristics between a wireless base station and a terminal station, and reduces electromagnetic interference based on the simulation results (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2001-168812 A Summary of the Invention [Problem to be solved by the invention]

[0005] In conventional technology, for example, when performing ray tracing in an environment with many structures, such as indoors, the ray is repeatedly reflected or diffracted by many structures before reaching the receiving point, resulting in an increase in the amount of calculations.

[0006] Furthermore, there are various formats for the environmental data used in radio wave propagation simulations, and with conventional technology, it took time to read the environmental data, which was an obstacle to speeding up the radio wave propagation simulations.

[0007] The embodiments of the present invention have been made in consideration of the above problems, and provide an information processing system that suppresses an increase in the amount of calculation in a radio wave propagation simulation and speeds up the radio wave propagation simulation. [Means for solving the problem]

[0008] In order to solve the above problems, an information processing system according to an embodiment of the present invention includes an acquisition unit that divides a target area into a plurality of meshes of a predetermined size and acquires mesh data representing the environment of the target area using height information for each of the plurality of meshes; a first ray tracing unit that calculates a two-dimensional ray tracing from a transmission point that transmits radio waves to a reception point that receives the radio waves based on the mesh data; a second ray tracing unit that calculates a three-dimensional ray tracing corresponding to the two-dimensional ray tracing based on the mesh data and height information of the transmission point and the reception point; and a radio wave intensity calculation unit that calculates the intensity of the radio waves at the reception point using one or more of the three-dimensional ray tracings calculated by the second ray tracing unit. Effect of the Invention

[0009] It is possible to provide an information processing system that suppresses an increase in the amount of calculation in a radio wave propagation simulation and speeds up the radio wave propagation simulation. [Brief description of the drawings]

[0010] [Figure 1] 1 is a diagram illustrating an example of the configuration of an information processing system according to an embodiment of the present invention. [Figure 2A] FIG. 1 is a diagram for explaining an overview of data processing according to the present embodiment; [Figure 2B] FIG. 2 is a diagram for explaining an overview of data processing according to the present embodiment; [Diagram 3] FIG. 2 is a diagram showing a method of dividing regional meshes. [Figure 4]4 is a flowchart illustrating an example of data processing according to the first embodiment. [Diagram 5] 13 is a flowchart illustrating another example of data processing according to the first embodiment. [Figure 6] 1 is a flowchart illustrating an example of a ray tracing process according to the first embodiment. [Figure 7] FIG. 2 is a diagram for explaining three-dimensional ray tracing according to the first embodiment. [Figure 8] 13 is a flowchart illustrating an example of a calculation process of a diffraction ray according to the second embodiment. [Figure 9A] FIG. 11 is a diagram for explaining an example of visibility determination according to the second embodiment. [Figure 9B] FIG. 13 is a diagram (2) for explaining an example of visibility determination according to the second embodiment. [Figure 9C] FIG. 3 is a diagram for explaining an example of visibility determination according to the second embodiment. [Figure 9D] FIG. 4 is a diagram for explaining an example of visibility determination according to the second embodiment. [Figure 10A] FIG. 11 is a diagram for explaining a process when there is no visibility according to the second embodiment. [Figure 10B] FIG. 13 is a diagram (2) for explaining the process when there is no visibility according to the second embodiment. [Figure 11] FIG. 11 is a diagram for explaining a process in a case where there are a plurality of structures according to the second embodiment. [Figure 12] 13 is a flowchart illustrating an example of a ray tracing process according to the third embodiment. [Figure 13] FIG. 2 illustrates an example of a hardware configuration of a computer. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present invention (the present embodiment) will be described with reference to the drawings. The embodiment described below is merely an example, and the embodiment to which the present invention is applied is not limited to the following embodiment.

[0012] <System configuration> 1 is a diagram showing an example of the configuration of an information processing system according to this embodiment. For example, the information processing system 1 realizes a data processing unit 10, a storage unit 20, a simulation unit 30, an interface unit 40, and the like by a computer included in the information processing system 1 executing a predetermined program. Note that each of the above functional configurations is not limited to a physical machine (computer), and may be realized by a program executed by a virtual machine on a cloud, for example. Also, each of the above functional configurations may be distributed and arranged on separate physical machines or virtual machines.

[0013] The storage unit 20 pre-stores environmental data 22 of a target area to be subjected to a radio wave propagation simulation. The environmental data 22 may include, for example, CAD (Computer Aided Design) data 101, building data 102, and point cloud data 103.

[0014] The CAD data 101 is, for example, three-dimensional CAD data including data indicating the width, height, shape, and position of each surface of an object (structure, building, etc.) in a target area, and information such as the reflectance and transmittance of radio waves on each surface. The CAD data 101 may be, for example, data input by an operator or the like into a three-dimensional CAD or the like, or may be data obtained by converting three-dimensional environmental map data created by SLAM (Simultaneous Localization and Mapping) technology into CAD data.

[0015] The building data 102 is a database (building database) including data indicating the width, height, shape, and position of each surface of a building in a target area, and information such as the reflectivity of radio waves on each surface. In this embodiment, the building data 102 includes information on each surface of the building, such as the walls, floors, ceilings, and pillars inside the building. The point cloud data 103 is, for example, three-dimensional point cloud data obtained using a LIDAR or the like, indicating the distance to each point of an object in the target area. Alternatively, the point cloud data 103 may be three-dimensional environmental map data or the like created based on three-dimensional point cloud information using a SLAM (Simultaneous Localization and Mapping) technique.

[0016] The storage unit 20 may be, for example, an external storage server of the information processing system 1, a cloud service, or the like.

[0017] (Data Processing Unit) The data processing unit 10 creates mesh data of a predetermined area in which the simulation unit 30 performs a radio wave propagation simulation, using environmental data 22, such as CAD data 101, building data 102, or point cloud data 103. The data processing unit 10 includes, for example, a division unit 11, an extraction unit 12, and a creation unit 13.

[0018] The dividing unit 11, for example, divides a target area to be the target of radio wave propagation simulation into a plurality of meshes. For example, as shown in Fig. 2A, the dividing unit 11 divides a target area 200 into a plurality of meshes 201 of a predetermined size. As one example, the dividing unit 11 divides the target area into the plurality of meshes 201 based on a regional mesh that divides a region into mesh-like regions based on latitude and longitude.

[0019] Fig. 3 shows a method of dividing a regional mesh published on the website of the Statistics Bureau of the Ministry of Internal Affairs and Communications (https: / / www.stat.go.jp / data / mesh / m_tuite.html). As an example, the division unit 11 divides the target area 200 into a plurality of meshes 201 according to the regional mesh division method of Fig. 3. Note that the regional mesh division method shown in Fig. 3 specifies only up to a quarter regional mesh, but the division unit 11 may extend the regional mesh division method of Fig. 3 according to a predetermined size, for example, to a quarter regional mesh, a sixteenth regional mesh, ..., etc.

[0020] As another example, the division unit 11 may divide the target area 200 into multiple meshes 201 based on the relative coordinates of the CAD data 101, when latitude and longitude information is not required, for example, when the simulation unit 30 performs an indoor radio wave propagation simulation.

[0021] Returning to FIG. 1, the functional configuration of the data processing unit 10 will be described. The extraction unit 12 extracts height information of each of a plurality of meshes 201, for example, as shown in FIG. 2A, from the environmental data 22. For example, the extraction unit 12 analyzes the CAD data 101, and when a structure with a height of 3 m is present in the mesh 201, the height information of the mesh 201 is set to 3 m. Note that, when the height information of the mesh 201 cannot be obtained, the extraction unit 12 may analyze other environmental data 22, such as building data 102, to extract the height information of the mesh 201. Also, when the extraction unit 12 analyzes the environmental data 22 and cannot obtain the height information of the mesh 201, the height information of the mesh 201 is set to 0.

[0022] The creation unit 13 creates mesh data 21 as shown in Fig. 2B, for example, using the height information of each mesh 211 extracted by the extraction unit 12. In the mesh data 21 shown in Fig. 2B, the x and y directions correspond to the position of each mesh 201 (for example, latitude, longitude, or row, column, etc.), and the value of each data indicates the height information of each mesh 201. Therefore, for example, in the mesh data 21, area 202 with height information "3" indicates that there is, for example, a structure with a height of 3m, and area 203 with height information "6" indicates that there is, for example, a structure with a height of 6m. Also, an area with height information "0" indicates that there is, for example, no structure.

[0023] As a result, the data processing unit 10 can convert data indicating the width, height, shape, position, etc. of each surface of objects (structures, buildings, etc.) within the target area, among the environmental data 22 stored in the storage unit 20, into two-dimensional mesh data 21 as shown in Fig. 2B. In addition, since this mesh data 21 has an image data format, it has the characteristic that it can be read and processed at high speed using a GPU (Graphicss Processing Unit).

[0024] Furthermore, since the mesh data 21 can be reused, when the simulation unit 30 performs a second or subsequent radio wave propagation simulation in the target area, the data processing unit 10 can omit the process of creating the mesh data 21.

[0025] (Simulation Department) The simulation unit 30 reads out the mesh data 21 created by the data processing unit 10 from the storage unit 20 or the like, and performs a radio wave propagation simulation of the target area. Here, the following description will be given assuming that the simulation unit 30 performs a radio wave propagation simulation of the target area by ray tracing. In ray tracing, the way in which radio waves (rays) transmitted from a transmission point are reflected, diffracted, or transmitted by structures along the way to reach a reception point is tracked (traced) as the trajectory of each ray, and the power of all rays that reach the reception point is added up to estimate the strength of the radio waves at the reception point.

[0026] However, with conventional technology, for example, when performing ray tracing in an environment with many structures, such as indoors, the ray repeatedly reflects, diffracts, or transmits through many structures before reaching the receiving point, which increases the amount of calculations and slows down the processing speed.

[0027] Therefore, in order to solve the above problems, the simulation unit 30 according to this embodiment has, for example, an acquisition unit 31, a unit vector calculation unit 32, a first ray tracing unit 33, a second ray tracing unit 34, and a radio wave intensity calculation unit 35.

[0028] The acquisition unit 31 acquires mesh data 21 of a target area for performing ray tracing from, for example, the storage unit 20. Preferably, the acquisition unit 31 reads out the mesh data 21 from the storage unit 20 at high speed using a GPU provided in the computer.

[0029] The unit vector calculation unit 32 calculates the unit vectors of each plane except the ceiling surface and the unit vectors of edges, using the mesh data 21 acquired by the acquisition unit 31. For example, the mesh data 21 represents structures within a building and the inside of the building except the ceiling (for example, walls, floors, pillars, etc.) as planes. The unit vector calculation unit 32 calculates the unit vectors of each of these planes and the unit vectors of edges formed by the intersection of planes. The function of the unit vector calculation unit 32 may be included in, for example, the first ray tracing unit 33 or the like.

[0030] The first ray tracing unit 33 obtains a two-dimensional ray trace from a transmission point that transmits radio waves to a reception point that receives radio waves, based on the mesh data 21. For example, the first ray tracing unit 33 emits a two-dimensional ray in the horizontal direction from the transmission point, and traces the two-dimensional ray to the reception point.

[0031] Based on the mesh data 21 and height information of the transmission points and reception points, the second ray tracing unit 34 determines a three-dimensional ray tracing corresponding to the two-dimensional ray tracing determined by the first ray tracing unit 33. For example, based on height information (antenna height) of the transmission points and reception points and height information of a structure, the second ray tracing unit 34 converts the two-dimensional ray tracing determined by the first ray tracing unit 33 into a three-dimensional ray tracing.

[0032] Preferably, when obtaining a three-dimensional ray trace, the second ray tracing section 34 obtains a reflected ray or a diffracted ray by restricting the emission angle of the ray launch based on, for example, Fermat's theorem.

[0033] In addition, when there is no line of sight between the transmitting point and the receiving point, the second ray tracing unit 34 replaces a structure between the transmitting point and the receiving point with, for example, a metal flat plate, and obtains a diffracted ray that undergoes screen diffraction through the metal flat plate.

[0034] Preferably, when there are multiple structures between the transmitting point and the receiving point, the second ray tracing unit 34 applies, for example, the Bullington model recommended in ITU-R Recommendation (ITU-R Recommendation P.526 "Propagation by diffraction") to obtain diffraction rays that diffract the multiple structures.

[0035] Further, the second ray tracing unit 34 uses, for example, the building data 102 to add reflected rays and diffracted rays from the ceiling surface of the building to the three-dimensional ray tracing obtained based on the mesh data 21.

[0036] The radio wave intensity calculation unit 35 calculates the intensity of the radio wave at the reception point using one or more three-dimensional ray traces obtained by the second ray tracing unit 34. For example, the radio wave intensity calculation unit 35 calculates the reflection coefficient and diffraction coefficient of one or more three-dimensional ray traces obtained by the second ray tracing unit 34, and calculates the total electric field intensity by adding up the electric field intensity of each ray.

[0037] In this manner, the acquisition unit 31 of the simulation unit 30 can acquire the mesh data 21, which is environmental data, from the storage unit 20 at high speed using the GPU.

[0038] In addition, in the simulation unit 30, the first ray tracing unit 33 obtains a two-dimensional ray trace from the transmitting point to the receiving point, and the second ray tracing unit 34 obtains a three-dimensional ray trace corresponding to the two-dimensional ray trace. Generally, when the strength of a radio wave at a receiving point is estimated by ray tracing, only a few rays contribute to the strength of the radio wave, and most rays are discarded in conventional techniques. On the other hand, the information processing system 1 according to this embodiment can speed up ray tracing without degrading accuracy by searching for the main rays.

[0039] Furthermore, when obtaining a three-dimensional ray trace corresponding to a two-dimensional ray trace, the simulation unit 30 restricts the emission angle of the ray launch to obtain a reflected ray or a diffracted ray, which enables the information processing system 1 to reduce the number of rays to be searched and further speed up the ray trace.

[0040] Furthermore, when calculating the diffracted rays diffracted by a plurality of structures between the transmitting point and the receiving point, the simulation unit 30 calculates the diffracted rays diffracted by a plurality of structures by applying the Bullington model. Since the Bullington model is simpler and has a faster calculation speed than other methods, the information processing system 1 can further increase the speed of ray tracing.

[0041] The interface unit 40 provides an API (Application Programming Interface) for other systems to utilize various functions provided by the information processing system 1, or a UI (User Interface) for users to utilize the functions. For example, a user (or another system) can use the interface unit 40 to request the data processing unit 10 to create mesh data 21, or to execute a radio wave propagation simulation. In addition, a user (or another system) can use the interface unit 40 to set parameters (e.g., the position of the transmission point, the position of the reception point, the frequency, the transmission output, etc.) required for the radio wave propagation simulation, or to register the environmental data 22 in the storage unit 20.

[0042] With the above configuration, according to this embodiment, it is possible to provide an information processing system 1 that suppresses an increase in the amount of calculation in a radio wave propagation simulation and speeds up the radio wave propagation simulation.

[0043] <Processing flow> Next, a process flow of the propagation environment data processing method according to this embodiment will be described.

[0044] [Example 1] (Data Processing 1) 4 is a flowchart showing an example of data processing according to the embodiment 1. This processing shows an example of data processing in which the data processing unit 10 creates mesh data 21 using environmental data 22.

[0045] In step S401, the division unit 11 of the data processing unit 10 selects a regional mesh that is equal to or smaller than a predetermined size from, for example, a regional mesh as shown in Fig. 3 or an expanded regional mesh (for example, a 1 / 8 regional mesh, a 1 / 16 regional mesh, ..., etc.). Here, the predetermined size may be set by a user or another system via the simulation unit 30, for example, or may be set in advance in the data processing unit 10.

[0046] In step S402, the division unit 11 divides the target area to be processed into a plurality of meshes each having the size of the regional mesh. For example, as shown in FIG. 2A, the division unit 11 divides the target area 200 into a plurality of meshes 201 each having the size of the regional mesh selected in step S401.

[0047] In step S403, the extraction unit 12 of the data processing unit 10 acquires the environmental data 22 of the target area, for example, from the storage unit 20. If the environmental data 22 uses relative coordinates instead of latitude and longitude, the latitude and longitude information of any point in the environmental data 22 is acquired in advance and stored, for example, in the environmental data 22. This allows the data processing unit 10 to associate the relative coordinates of the environmental data 22 with the latitude and longitude.

[0048] In step S404, the data processing unit 10 executes the processes of steps S405 to S408 for each of the plurality of meshes 201.

[0049] In step S405, the extraction unit 12 of the data processing unit 10 extracts height information of the mesh 201 to be processed from the environmental data 22. When there are multiple pieces of environmental data 22, such as CAD data 101, building data 102, and point cloud data 103, it is advisable to determine the priority of each piece of data in advance. In this case, the extraction unit 12 may attempt to obtain height information from data with a higher priority and extract the height information that is obtained first.

[0050] In step S405, the creation unit 13 of the data processing unit 10 judges whether or not the environmental data 22 contains height information for the mesh 201 to be processed. For example, if the extraction unit 12 is able to acquire height information from the environmental data 22, the creation unit 13 judges that there is height information. On the other hand, if the extraction unit 12 is unable to acquire height information from the environmental data 22, the creation unit 13 judges that there is no height information. If there is height information, the creation unit 13 shifts the process to step S407. On the other hand, if there is no height information, the creation unit 13 shifts the process to step S408.

[0051] In step S407, the creation unit 13 inputs the height information extracted by the extraction unit 12 to the mesh data of the mesh 201 to be processed. On the other hand, in step S408, the creation unit 13 inputs 0 to the mesh data of the mesh 201 to be processed.

[0052] The data processing unit 10 executes the processes of steps S405 to S408 described above for each of the plurality of meshes 201, thereby generating mesh data 21 as shown in FIG. 2B, for example.

[0053] (Data Processing 2) 5 is a flowchart showing an example of data processing according to the embodiment 2. This processing shows another example of data processing in which the data processing unit 10 creates mesh data 21 using environmental data 22.

[0054] In the process described in Fig. 4, an example has been described in which the data processing unit 10 divides the target area into regional meshes, for example, as shown in Fig. 3. However, this is not limited to this, and the data processing unit 10 may divide the target area into a plurality of meshes of a predetermined size, for example, based on the relative coordinates of the environmental data 22 (for example, the CAD data 101, etc.).

[0055] For example, when performing a radio wave propagation simulation indoors, such as inside a building, latitude and longitude information is often not required. Also, since indoor structures are often arranged along the walls or pillars of a building, for example, it may be better to divide the target area into a predetermined size based on the relative coordinates of the environment data 22.

[0056] Here, an example of processing will be described in which the data processing unit 10 divides the target area into a plurality of meshes of a predetermined size based on, for example, the relative coordinates of the environmental data 22. Among the processing shown in Fig. 5, the processing of steps S404 to S408 is similar to the processing described in Fig. 4, so here, differences from the processing described in Fig. 4 will be mainly described.

[0057] In step S501, the division unit 11 of the data processing unit 10 acquires the environmental data 22 of the target area, for example, from the storage unit 20. For example, when performing a radio wave propagation simulation on a certain floor in a building, the division unit 11 acquires the environmental data 22 of the floor.

[0058] In step S502, the dividing unit 11 divides the target area into a plurality of meshes of a predetermined size. For example, the dividing unit 11 divides the target area 200 into a plurality of meshes 201 of a predetermined size, as shown in FIG. 2A, based on the relative coordinates of the acquired environmental data 22 (e.g., CAD data 101).

[0059] In step S404, the data processing unit 10 executes the processes of steps S405 to S408 for each of the multiple meshes 201. In this way, the data processing unit 10 can create mesh data 21 as shown in FIG. 2(B), for example.

[0060] (Ray tracing processing) Fig. 6 is a flowchart showing an example of ray tracing processing according to the first embodiment. An example of processing when ray tracing is performed in an indoor environment will be described here. In addition, an imaging method and a ray-launching method are generally known as ray tracing algorithms, and an example of processing using the ray-launching method will be described here. In the ray-launching method, rays are emitted from a transmission point at a constant angle, and a trajectory is geometrically traced while performing an intersection determination with a wall surface or an edge of a wall surface for each emitted ray, thereby determining a ray that reaches a reception point.

[0061] In step S601, the data processing unit 10 creates mesh data 21 from the environmental data 22, for example, by the data processing described in Fig. 4 or Fig. 5. If the data processing unit 10 has already created the mesh data 21, the process of step S601 can be omitted. Also, the data processing unit 10 may execute the process of step S601 in advance at another timing (for example, batch processing at night, etc.).

[0062] In step S602, the acquisition unit 31 reads the mesh data 21 of the target area for ray tracing from the storage unit 20 or the like, using the GPU.

[0063] In step S603, the unit vector calculation unit 32 uses the mesh data 21 acquired by the acquisition unit 31 to calculate unit vectors of each plane, excluding the ceiling plane, and unit vectors of edges in the target area for ray tracing.

[0064] In step S604, the first ray tracing unit 33 obtains a two-dimensional ray trace from a transmission point that transmits radio waves to a reception point that receives radio waves, based on the mesh data 21. For example, the first ray tracing unit 33 emits a two-dimensional ray in the horizontal direction from the transmission point and transmits the ray for a maximum number of times N T , maximum number of reflections N R , and the maximum number of diffractions N DA two-dimensional ray that reaches the receiving point is traced within the range of . This results in a two-dimensional ray trace that does not take into account reflections on the ceiling and floor, for example.

[0065] In addition, the maximum number of passes N T , maximum number of reflections N R , and the maximum number of diffractions N D may be set before starting ray tracing, for example, by using the interface unit 40. Also, the first ray tracing unit 33 may set the maximum number of reflections N R , and the maximum number of diffractions N D If the setting is not set, the default value (for example, N T =1, N R =1, N D =1, etc.) to obtain a two-dimensional ray trace.

[0066] In step S605, the second ray tracing unit 34 converts the two-dimensional ray tracing obtained by the first ray tracing unit 33 in step S604 into a three-dimensional ray tracing.

[0067] Fig. 7 is a diagram for explaining three-dimensional ray tracing according to the first embodiment. In Fig. 7, the dashed arrow indicates an example of a two-dimensional ray tracing 711 obtained by the first ray tracing unit 33. The two-dimensional ray tracing 711 is a two-dimensional ray tracing in which a two-dimensional ray emitted from a transmitting point is diffracted at an edge of a structure 703b, reflected at a plane of a structure 703a, and reaches a receiving point.

[0068] The two-dimensional ray traces obtained by the first ray tracing unit 33 also include two-dimensional ray traces that reach the receiving point directly from the transmitting point, and two-dimensional ray traces that reach the receiving point by being reflected, diffracted, or transmitted by other structures or walls of buildings, etc. Here, as an example for explanation, a two-dimensional ray trace 311 with one reflection and one diffraction is shown.

[0069] The second ray tracing unit 34, for example, adds the height h1 of the transmitting point 701, the height h2 of the receiving point 702, and the heights of the structures 703a and 703b to the two-dimensional ray trace 711 shown in FIG. 7 to obtain a three-dimensional ray trace 712 corresponding to the two-dimensional ray trace 711.

[0070] For example, the second ray tracing unit 34 re-emits the three-dimensional ray that intersects with the plane of the structure 703a, etc., in the reflection direction. At this time, the second ray tracing unit 34 calculates a unit direction vector r that satisfies the following formula (1) based on Fermat's theorem. R ^ to keep the reflected rays and, for example, to filter out other reflected rays.

[0071]

number

[0072] In formula (1), r in ^ is a unit direction vector indicating the incident direction of the ray, and n^ indicates a unit vector (normal vector) of the plane where the ray intersects. By restricting the direction in which the reflected ray is emitted in this way, the information processing system 1 can reduce the amount of calculation of the three-dimensional ray.

[0073] The second ray tracing unit 34 also re-emits the three-dimensional ray that intersected with the edge of the structure 703a in the diffraction direction. At this time, the second ray tracing unit 34 calculates a unit direction vector r that satisfies the following formula (2) based on Fermat's theorem. D ^ diffracted rays and exclude other diffracted rays, for example.

[0074]

number

[0075] In addition, the second ray tracing unit 34 also obtains, for example, reflected rays and diffracted rays from the floor surface by adding the height h1 of the transmission point 701 and the height h2 of the reception point 702 to the two-dimensional ray tracing 711 shown in FIG.

[0076] In step S606, the second ray tracing unit 34 adds reflected rays and diffracted rays from the ceiling surface to the three-dimensional ray tracing obtained in step S605. For example, the second ray tracing unit 34 refers to the building data 102 (or the CAD data 101) or the like to identify a plane representing the ceiling of the building, and obtains rays that are reflected or diffracted by the ceiling surface from the transmission point 701 and reach the reception point 702.

[0077] In step S607, the radio wave intensity calculation unit 35 calculates the intensity of the radio wave (e.g., electric field intensity) at the reception point using all three-dimensional ray tracing obtained by the second ray tracing unit 34. For example, the radio wave intensity calculation unit 35 acquires information such as the reflectance and transmittance of the radio wave on each surface inside the structure and the building from the environmental data 22, calculates the reflection coefficient, diffraction coefficient, and transmission coefficient of all the rays found, and calculates the total electric field intensity by adding up the electric field intensities of all the rays. Note that the process of step S612 can be performed using a conventional ray tracing method.

[0078] As described above, according to the first embodiment, it is possible to provide the information processing system 1 that suppresses an increase in the amount of calculation in a radio wave propagation simulation and speeds up the radio wave propagation simulation.

[0079] [Example 2] In the second embodiment, an example of calculation processing of a diffraction ray executed by the second ray tracing unit 34 when converting a two-dimensional ray trace into a three-dimensional ray trace in step S604 in FIG. 6 will be described.

[0080] FIG. 8 is a flowchart illustrating an example of a calculation process of a diffraction ray according to the second embodiment.

[0081] In step S801, the second ray tracing unit 34 determines whether the target ray is a diffracted ray, and if it is a diffracted ray, executes the processes in and after step S802.

[0082] In step S802, the second ray tracing unit 34 determines whether there is line of sight between the transmission point and the reception point. For example, when a radio wave (ray) emitted from the transmission point reaches the reception point directly, the second ray tracing unit 34 determines that there is line of sight between the transmission point and the reception point.

[0083] 9A to 9D are diagrams for explaining an example of line-of-sight determination according to the first embodiment. In the two-dimensional ray trace in the horizontal plane obtained in step S604 in FIG. 6, the second ray tracer 34 determines whether or not a structure 902 is present on a path 901 between a transmission point 701 and a reception point 702, for example, as shown in FIG. 9A. If the structure 902 is not present on the path 901 between the transmission point 701 and the reception point 702, the second ray tracer 34 determines that there is line-of-sight between the transmission point 701 and the reception point 702.

[0084] On the other hand, when a structure 902 is present on the path 901 between the transmission point 701 and the reception point 702, the second ray tracing unit 34 performs line-of-sight determination on a vertical plane passing through the transmission point 701 and the reception point 702, for example, as shown in FIG. 9B and FIG. 9C. For example, as shown in FIG. 9B, when a structure 902 is present on the path 901 between the transmission point 701 and the reception point 702, the second ray tracing unit 34 determines that there is no line-of-sight between the transmission point 701 and the reception point 702. On the other hand, as shown in FIG. 9C, when a structure 902 is not present on the path 901 between the transmission point 701 and the reception point 702, the second ray tracing unit 34 determines that there is line-of-sight between the transmission point 701 and the reception point 702. In this case, when obtaining a three-dimensional ray trace, the second ray tracing unit 34 obtains a ray 903 reflected by the top surface of the structure 902, as shown in FIG. 9D, instead of a ray reflected by the floor surface.

[0085] In the above description, the second ray tracing unit 34 is described as performing the above-mentioned visibility determination, but this is not limited to the above. For example, the simulation unit 30 may have a visibility determination unit that performs the above-mentioned visibility determination.

[0086] Returning now to Fig. 8, the description of the flowchart will be continued. In step S802, if there is line of sight between the transmission point and the reception point, the second ray tracing unit 34 shifts the process to step S803. On the other hand, if there is no line of sight between the transmission point and the reception point, the second ray tracing unit 34 shifts the process to step S804.

[0087] In step S803, the second ray tracing unit 34 calculates the diffraction rays diffracted by the edge of the structure or the like, for example, as described with reference to FIG.

[0088] On the other hand, in step S804, the second ray tracing unit 34 replaces structures between the transmission point and the reception point with metal flat plates.

[0089] In step S805, the second ray tracing unit 34 determines whether or not there are multiple structures between the transmission point and the reception point, and if there are not multiple structures, the second ray tracing unit 34 shifts the process to step S806. On the other hand, if there are multiple structures between the transmission point and the reception point, the second ray tracing unit 34 shifts the process to step S807.

[0090] In step S806, the second ray tracing unit 34 calculates a diffracted ray that is subjected to screen diffraction from the metal plate that replaces the structure between the transmission point and the reception point.

[0091] On the other hand, in step S807, the second ray tracing unit 34 uses the Bullington model to calculate diffracted rays for analyzing a plurality of structures between the transmitting point and the receiving point.

[0092] 10A and 10B are diagrams for explaining a process in a case where there is no line of sight according to the second embodiment. As shown in Fig. 10A, when there is one structure 1001 between a transmission point 701 and a reception point 702, the second ray tracing unit 34 replaces the structure 1001 with a metal flat plate 1002 as shown in Fig. 10B. In addition, the second ray tracing unit 34 calculates the screen diffracted waves above and to the left and right of the metal flat plate 1002 to obtain the diffracted rays.

[0093] Fig. 11 is a diagram for explaining an example of processing when there are multiple structures according to the second embodiment. When there are multiple structures between the transmission point 701 and the reception point 702, the second ray tracing unit 34 replaces the multiple structures with multiple metal flat plates 1002a, 1002b, and 1002c as shown in Fig. 11. In addition, the second ray tracing unit 34 applies the Bullington model to obtain diffracted rays diffracting the multiple metal flat plates 1002a, 1002b, and 1002c.

[0094] For example, the second ray tracing unit 34 obtains a virtual blocking point 1103 which is an intersection between a transmitting side line of sight 1101 passing through the transmitting point 701 and the upper end of the metal flat plate 1002c and a receiving side line of sight 1102 passing through the receiving point 702 and the upper end of the metal flat plate 1002a. The second ray tracing unit 34 also obtains a diffracted ray by calculating a diffracted wave diffracted by a virtual knife edge (Barrington edge) at the virtual blocking point 1103. With this method, the second ray tracing unit 34 can obtain a diffracted ray diffracted by a plurality of structures with a smaller amount of calculation.

[0095] By the above process, the second ray tracing unit 34 can speed up the calculation of the diffraction rays when there is no line of sight between the transmitting point and the receiving point.

[0096] [Example 3] Fig. 12 is a flowchart showing an example of ray tracing processing according to the embodiment 3. Note that, among the processing shown in Fig. 12, the processing other than step S1201 is similar to the ray tracing processing according to the embodiment 1 described in Fig. 6, so here, differences from the processing according to the embodiment 1 will be mainly described.

[0097] In step S604 of FIG. 6, the first ray tracing unit 33 performs the maximum number of transmissions N T , maximum number of reflections N R , and the maximum number of diffractions N D We sought to find a two-dimensional ray trace from the transmitting point to the receiving point within this range.

[0098] On the other hand, in step S1201 of FIG. 12, the first ray tracing unit 33 calculates a two-dimensional ray trace by limiting the path from the transmission point to the reception point via structures within the building to a path from the transmission point to the reception point via structures that are visible from the transmission point or the reception point.

[0099] For example, the first ray tracing unit 33 identifies structures within a building that are visible from a transmission point (hereinafter referred to as Tx line-of-sight structures) and structures within a reception point (hereinafter referred to as Rx line-of-sight structures). As a specific example, when the environmental data 22 includes three-dimensional point cloud data 103 acquired by LIDAR, the first ray tracing unit 33 may identify Tx line-of-sight structures and Rx line-of-sight structures using the point cloud data 103. As another example, the first ray tracing unit 33 may analyze the mesh data 21 or three-dimensional CAD data or the like included in the environmental data 22 to identify Tx line-of-sight structures and Rx line-of-sight structures.

[0100] Moreover, the first ray tracing unit 33 determines a two-dimensional ray trace by limiting the paths from the transmission point to the reception point via structures inside the building to, for example, the following three paths. 1) The path from the transmitting point through the Tx line-of-sight structure to the receiving point. 2) The path from the transmitting point to the receiving point via the Tx line-of-sight structure and the Rx line-of-sight structure. 3) The path from the transmitting point through the Rx line-of-sight structure to the receiving point.

[0101] This allows the first ray tracing unit 33 to obtain the main rays that contribute to estimating the radio wave intensity at the reception point at a faster speed and with a smaller amount of calculation.

[0102] The above three routes are merely examples, and various modifications or applications are possible. For example, the Tx line-of-sight structures and the Rx line-of-sight structures may include walls or pillars of buildings included in the building data 102.

[0103] As described above, according to the third embodiment, it is possible to provide an information processing system that can further suppress an increase in the amount of calculation when performing ray tracing in an environment where many structures exist, such as indoors.

[0104] In the above embodiments, examples of performing ray tracing indoors have been described, but the ray tracing method according to this embodiment can also be applied to performing ray tracing outdoors where there are many structures, for example by replacing the floor with the ground.

[0105] <Hardware configuration example> The information processing system 1 according to this embodiment can be realized, for example, by causing a computer to execute a program in which the processing contents described in this embodiment are described.

[0106] The above program can be recorded on a computer-readable recording medium (such as a portable memory) and can be stored or distributed. The above program can also be provided via a network such as the Internet or e-mail.

[0107] Fig. 13 is a diagram showing an example of the hardware configuration of a computer. A computer 1300 in Fig. 13 includes a drive device 1301, an auxiliary storage device 1303, a memory device 1304, a CPU 1305, an interface device 1306, a display device 1307, an input device 1308, an output device 1309, and a GPU 1310, which are all connected to each other via a bus B.

[0108] A program for implementing processing in computer 1300 is provided by a recording medium 1302 such as a CD-ROM or a memory card. When recording medium 1302 storing the program is set in drive device 1301, the program is installed from recording medium 1302 via drive device 1301 into auxiliary storage device 1303. However, the program does not necessarily have to be installed from recording medium 1302, and may be downloaded from another computer via a network. Auxiliary storage device 1303 stores the installed program as well as necessary files, data, and the like.

[0109] The memory device 1304 reads out and stores the program from the auxiliary storage device 1303 when an instruction to start the program is received. The CPU 1305 realizes the functions related to each unit described in this embodiment according to the program stored in the memory device 1304. The interface device 1306 is used as an interface for connecting to a network. The display device 1307 displays a GUI or the like according to a program. The input device 1308 is composed of a keyboard and a mouse, buttons, a touch panel, or the like, and is used to input various operation instructions. The output device 1309 outputs the results of calculations. Note that the information processing system 1 may not include either or both of the display device 1307 and the input device 1308. The GPU 1310 is a processor that executes various processes related mainly to image processing (especially 3D graphics processing) faster than the CPU 1305.

[0110] <Effects of the embodiment> According to the technology of the present embodiment, it is possible to provide an information processing system that suppresses an increase in the amount of calculation in a radio wave propagation simulation and speeds up the radio wave propagation simulation.

[0111] <Summary of the embodiment> This specification discloses at least the following information processing system, propagation environment simulation method, and program. (Section 1) an acquisition unit that divides a target area into a plurality of meshes of a predetermined size and acquires mesh data that represents an environment of the target area using height information of each of the plurality of meshes; a first ray tracing unit that obtains a two-dimensional ray trace from a transmitting point that transmits radio waves to a receiving point that receives the radio waves based on the mesh data; a second ray tracing unit that obtains a three-dimensional ray tracing corresponding to the two-dimensional ray tracing based on the mesh data and height information of the transmission points and the reception points; a radio wave intensity calculation unit that calculates the intensity of the radio wave at the reception point by using one or more of the three-dimensional ray traces obtained by the second ray trace unit; An information processing system having the above configuration. (Section 2) the mesh data has a data format readable by a GPU; 2. The information processing system according to claim 1, wherein the acquisition unit reads the mesh data using a GPU. (Section 3) A division unit that divides the target area into a plurality of meshes of the predetermined size; an extraction unit that extracts height information of each of the plurality of meshes using environmental data that represents the position and shape of an object in the target area; a creation unit that creates the mesh data representing the height information of each of the plurality of meshes; 3. The information processing system according to claim 1 or 2, (Section 4) the mesh data represents structures within a building and the inside of the building excluding a ceiling, using a plurality of planes; the first ray tracing unit determines, based on the mesh data, a two-dimensional ray trace from the transmission point that transmits radio waves within the building to the reception point that receives the radio waves within the building; The second ray tracing unit includes: determining a three-dimensional ray trace corresponding to the two-dimensional ray trace based on the height information of the transmission points and the reception points and the mesh data; adding reflected rays and diffracted rays from a ceiling surface of the building to the three-dimensional ray trace based on the data of the building; 4. An information processing system according to any one of claims 1 to 3. (Section 5) 5. The information processing system according to any one of claims 1 to 4, wherein the first ray tracing unit determines the two-dimensional ray tracing by limiting a path from the transmitting point to the receiving point via a structure to a path from the transmitting point to the receiving point via a structure that is visible from the transmitting point or the receiving point. (Section 6) The information processing system according to any one of claims 1 to 5, wherein the second ray tracing unit, when obtaining a reflected or diffracted ray in the three-dimensional ray tracing, constrains the exit angle of a ray launch to obtain the reflected or diffracted ray. (Section 7) The information processing system according to any one of claims 1 to 6, wherein, when obtaining a diffraction ray in the three-dimensional ray tracing, if there is no line of sight on the path between the transmission point and the reception point, the second ray tracing unit obtains the diffraction ray by replacing structures between the transmission point and the reception point with metal flat plates. (Section 8) 8. The information processing system according to claim 7, wherein, when there are multiple structures between the transmitting point and the receiving point, the second ray tracing unit uses a Bullington model to determine the diffraction rays that diffract the multiple structures. (Section 9) The information processing system an acquisition process of dividing a target area into a plurality of meshes of a predetermined size and acquiring mesh data representing the environment of the target area using height information of each of the plurality of meshes; a first ray tracing process for obtaining a two-dimensional ray tracing from a transmitting point that transmits radio waves to a receiving point that receives the radio waves based on the mesh data; a second ray tracing process for obtaining a three-dimensional ray tracing corresponding to the two-dimensional ray tracing based on the mesh data and height information of the transmission points and the reception points; a radio wave intensity calculation process for calculating the intensity of the radio wave at the reception point using one or more of the three-dimensional ray traces obtained in the second ray trace process; A radio wave propagation simulation method. (Section 10) Information processing system, an acquisition process of dividing a target area into a plurality of meshes of a predetermined size and acquiring mesh data representing the environment of the target area using height information of each of the plurality of meshes; a first ray tracing process for obtaining a two-dimensional ray tracing from a transmitting point that transmits radio waves to a receiving point that receives the radio waves based on the mesh data; a second ray tracing process for obtaining a three-dimensional ray tracing corresponding to the two-dimensional ray tracing based on the mesh data and height information of the transmission points and the reception points; a radio wave intensity calculation process for calculating the intensity of the radio wave at the reception point using one or more of the three-dimensional ray traces obtained in the second ray trace process; A program to execute.

[0112] Although the present embodiment has been described above, the present invention is not limited to such a specific embodiment, and various modifications and variations are possible within the scope of the gist of the present invention described in the claims. [Explanation of symbols]

[0113] 1. Information Processing Systems 10 Data Processing Section 11 Division 12 Extraction part 13 Creation Department 21 Mesh data 31 Acquisition Department 33 First Raytrace Section 34 Second Raytrace Section 35 Radio wave intensity calculation unit 22 Environmental Data 30 Simulation Section 101 CAD data 102 Building Data 103 Point Cloud Data 1301 Drive device 1302 Recording media 1303 Auxiliary storage device 1304 Memory device 1305 CPU 1306 Interface Device 1307 Display device 1308 Input Device 1309 Output Device 1310 GPU

Claims

1. an acquisition unit that divides a target area into a plurality of meshes of a predetermined size and acquires mesh data that represents an environment of the target area using height information of each of the plurality of meshes; a first ray tracing unit that obtains a two-dimensional ray trace from a transmitting point that transmits radio waves to a receiving point that receives the radio waves based on the mesh data; a second ray tracing unit that obtains a three-dimensional ray tracing corresponding to the two-dimensional ray tracing based on the mesh data and height information of the transmission points and the reception points; a radio wave intensity calculation unit that calculates the intensity of the radio wave at the reception point by using one or more of the three-dimensional ray traces obtained by the second ray trace unit; An information processing system having the above configuration.

2. the mesh data has a data format readable by a GPU; The information processing system according to claim 1 , wherein the acquisition unit reads the mesh data with a GPU.

3. A division unit that divides the target area into a plurality of meshes of the predetermined size; an extraction unit that extracts height information of each of the plurality of meshes using environmental data that represents the position and shape of an object in the target area; a creation unit that creates the mesh data representing the height information of each of the plurality of meshes; The information processing system according to claim 1 or 2, further comprising:

4. the mesh data represents structures within a building and the inside of the building excluding a ceiling, using a plurality of planes; the first ray tracing unit determines, based on the mesh data, a two-dimensional ray trace from the transmission point that transmits radio waves within the building to the reception point that receives the radio waves within the building; The second ray tracing unit includes: determining a three-dimensional ray trace corresponding to the two-dimensional ray trace based on the height information of the transmission points and the reception points and the mesh data; adding reflected rays and diffracted rays from a ceiling surface of the building to the three-dimensional ray trace based on the data of the building; The information processing system according to claim 1 .

5. 5. The information processing system according to claim 1, wherein the first ray tracing unit determines the two-dimensional ray tracing by limiting a path from the transmission point to the reception point via a structure to a path from the transmission point to the reception point via a structure that has a line of sight to the transmission point or the reception point.

6. The information processing system according to claim 1 , wherein the second ray tracing unit, when determining a reflected or diffracted ray in the three-dimensional ray tracing, determines the reflected or diffracted ray by restricting an exit angle of a ray launch.

7. 7. The information processing system according to claim 1, wherein when a diffracted ray is obtained in the three-dimensional ray tracing, if there is no line of sight on a path between the transmission point and the reception point, the second ray tracing unit obtains the diffracted ray by replacing a structure between the transmission point and the reception point with a metal flat plate.

8. The information processing system according to claim 7 , wherein when there are a plurality of structures between the transmitting point and the receiving point, the second ray tracing unit uses a Bullington model to obtain the diffracted rays that diffract the plurality of structures.

9. The information processing system an acquisition process of dividing a target area into a plurality of meshes of a predetermined size and acquiring mesh data representing the environment of the target area using height information of each of the plurality of meshes; a first ray tracing process for obtaining a two-dimensional ray tracing from a transmitting point that transmits radio waves to a receiving point that receives the radio waves based on the mesh data; a second ray tracing process for obtaining a three-dimensional ray tracing corresponding to the two-dimensional ray tracing based on the mesh data and height information of the transmission points and the reception points; a radio wave intensity calculation process for calculating the intensity of the radio wave at the reception point using one or more of the three-dimensional ray traces obtained in the second ray trace process; A radio wave propagation simulation method.

10. Information processing system, an acquisition process of dividing a target area into a plurality of meshes of a predetermined size and acquiring mesh data representing the environment of the target area using height information of each of the plurality of meshes; a first ray tracing process for obtaining a two-dimensional ray tracing from a transmitting point that transmits radio waves to a receiving point that receives the radio waves based on the mesh data; a second ray tracing process for obtaining a three-dimensional ray tracing corresponding to the two-dimensional ray tracing based on the mesh data and height information of the transmission points and the reception points; a radio wave intensity calculation process for calculating the intensity of the radio wave at the reception point using one or more of the three-dimensional ray traces obtained in the second ray trace process; A program to execute.

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