Propagation environment estimation method, propagation environment estimation system, and propagation environment estimation device

Abstract

This disclosure relates to a propagation environment estimation method suitable for radio signal environment estimation using a scale model. This propagation environment estimation method includes the following steps. A scale model is created (step 1). A light source capable of emitting directional light and scanning in the irradiation direction is installed in the scale model so as to simulate a radio wave transmitting station (step 2). A receiver marker simulating a radio wave receiving station is installed in the scale model (step 3). The scale model is filled with smoke using a smoke generator (step 4). The light source scans through the scale model (step 5). A camera captures an image of the path of light when the receiver marker is irradiated with light (step 6). Path propagation information is estimated from the image captured by the camera (step 7).

Description

[Technical Field]

[0001] The present disclosure relates to a propagation environment estimation method, a propagation environment estimation system, and a propagation environment estimation device, and more particularly to a propagation environment estimation method, a propagation environment estimation system, and a propagation environment estimation device that are suitable for estimating the environment of a wireless signal using a scale model. [Background technology]

[0002] In recent years, the explosive spread of wireless communication devices has led to an increasing demand for wireless communication. However, the frequency resources available for wireless communication are limited. This has made it necessary to utilize previously unused frequencies in addition to existing frequencies. When using a new frequency band, it is necessary to investigate in advance the propagation characteristics of wireless signals in the service area and the impact of interference that signals in the new frequency band may have on other systems.

[0003] In response to these demands, the International Telecommunication Union (ITU) Radiocommunication Sector (ITU-R) is attempting to measure the propagation characteristics of wireless signals in real areas and develop propagation models based on various measurement results. However, these types of attempts face challenges, such as insufficient measurement results for unexplored frequencies and insufficient development of propagation models.

[0004] Non-Patent Document 1 listed below discloses a method for estimating the radio wave reflection conditions in a mobile communication environment using a scale model. In this method, a scale model of an actual urban area or the like is created at a scale of, for example, 1 / 100. Then, a radio signal is generated in the environment of the scale model, and the radio wave reflection conditions are estimated. This method can significantly reduce the cost required to collect the necessary data compared to actually measuring the propagation environment in an actual urban area. [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] Ryuichiro Iwakuma, Yu Funaki, Toyokazu Mine, Shinichi Ichitsubo, “Delay Profile Using Scale Model Method for Microcells in Urban Areas,” 2010 International Conference on Broadband, Wireless Computing, Communication and Applications, Nov. 2010. Summary of the Invention [Problem to be solved by the invention]

[0006] As described above, conventional methods using scale models estimate the propagation environment by actually measuring the behavior of radio waves in a scale model environment. In measurements using radio waves, for example, multiple antennas are placed at the measurement point and the arrival direction can be estimated by analyzing the phase difference of the radio waves arriving at them. Alternatively, the arrival direction can be estimated by placing an antenna with sharp directivity at the measurement point and performing omnidirectional scanning with that antenna.

[0007] However, with the estimation method using radio waves, although it is possible to estimate the direction of arrival of a path as described above, there is a problem in that it is not possible to directly estimate the propagation distance of the path, the number of reflections, or the reflection position.

[0008] In order to solve the above-mentioned problems, the present disclosure aims to provide a propagation environment estimation method, a propagation environment estimation system, and a propagation environment estimation device that can estimate the propagation distance, number of reflections, and reflection positions of a path by filling a scale model with smoke and then scanning it with a directional light-emitting element that is treated as a transmitter. [Means for solving the problem]

[0009] A first aspect of the present disclosure is a propagation environment estimation method for estimating a radio wave propagation environment using a scale model, and preferably the propagation environment estimation method includes: a model creation step of creating a scale model; a light source installation step of installing a light source on the scale model that emits directional light and is capable of scanning the irradiation direction, simulating a radio wave transmitting station; a receiving marker installation step of installing a receiving marker on the scale model that resembles a radio wave receiving station; a smoke generation step of filling the scale model with smoke using a smoke generator; a scanning step of scanning the inside of the scale model with the light source; an imaging step of using a camera to capture the light path when light is irradiated onto the receiving marker; and an estimation step of estimating path propagation information from the image captured by the camera.

[0010] A second aspect of the present disclosure is a propagation environment estimation system that estimates the propagation environment of radio waves using a scale model, and preferably includes a 3D printer that creates the scale model, an element mounter that installs a light source and a receiving marker on the scale model, a smoke generator that fills the scale model with smoke, an imaging device that captures an image of the path of light irradiated from the light source to the receiving marker, and a control device that controls the 3D printer, the element mounter, the smoke generator, and the imaging device, and the control device estimates path propagation information from an image acquired by capturing the image.

[0011] A third aspect of the present disclosure is a propagation environment estimation device that estimates a radio wave propagation environment using a scale model, and includes a 3D printer unit that creates the scale model, an element mounter unit that installs a light source and a receiving marker on the scale model, a smoke generator unit that fills the scale model with smoke, an imaging device unit that captures an image of the path of light irradiated from the light source to the receiving marker, and a control device unit that controls the 3D printer unit, the element mounter unit, the smoke generator unit, and the imaging device unit, and it is preferable that the control device unit is a propagation environment estimation device that estimates path propagation information from an image acquired by capturing. [Effects of the Invention]

[0012] According to the first to third aspects of the present disclosure, by filling a scale model with smoke and then scanning it with a directional light-emitting element that acts as a transmitter, it is possible to estimate the propagation distance, number of reflections, and reflection position of the path. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 10 is a perspective view of a scale model used in a propagation environment estimation method of a comparative example. [Figure 2] 10 is a flowchart for explaining an outline of a propagation environment estimation method of a comparative example. [Figure 3] 1 is a perspective view of a scale model used in a propagation environment estimation method according to a first embodiment of the present disclosure. [Figure 4] 1 is a flowchart showing an overview of a propagation environment estimation method according to a first embodiment of the present disclosure. [Figure 5] 3 is a flowchart showing in detail the procedure of a propagation environment estimation method according to the first embodiment of the present disclosure. [Figure 6] 1 is a block diagram showing the configuration of a propagation environment estimation system that performs a series of processes according to a first embodiment of the present disclosure continuously and fully automatically. [Figure 7] FIG. 11 is a perspective view of a scale model used in a propagation environment estimation method according to a second embodiment of the present disclosure. [Figure 8] FIG. 11 is a perspective view of a scale model used in a propagation environment estimation method according to a third embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0014] Embodiment 1 [Comparative Example Overview] Prior to describing the first embodiment, a comparative example will be briefly outlined. Fig. 1 is a perspective view of a scale model used in a propagation environment estimation method of the comparative example. The left diagram shows a case where a hollow point on the scale model is set as a measurement point of radio waves. The right diagram shows a case where a point on the ground surface on the scale model is set as a measurement point of radio waves.

[0015] When attempting to estimate the propagation environment using a scale model, one possible method is to create a miniature model of an indoor or outdoor target area at an arbitrary scale, scan a directional light-emitting element that acts as a transmitter, and estimate the direction of arrival of the radio waves from the position where the light is irradiated on a sphere installed at the receiving position. Figure 1 shows a miniature model that can be used in this method.

[0016] Fig. 2 is a flowchart for explaining an outline of the propagation environment estimation method of the comparative example. As shown in Fig. 2, in the propagation environment estimation method of the comparative example, estimation of the propagation environment proceeds in the following steps.

[0017] First, a model of the target area is created (step 202). Hereinafter, this model will be referred to as a "scale model." A scale model is a reproduction of an actual urban space, for example, at a scale of about 1 / 100. While FIG. 2 shows an example in which an outdoor space is used as the target area, the interior of a specific building may also be used as the target area.

[0018] Next, a light source is set up to act as a radio wave transmission source (step 204). The light source is preferably a laser pointer or the like, which is a directional light-emitting element that emits laser light with excellent linearity. The light source is also configured to be able to scan the irradiation direction of the laser light in three dimensions.

[0019] Next, the light-receiving sphere 50 or 52 is placed so that the measurement point set on the scale model is at its center (step 206). The light-receiving spheres 50 and 52 are made of a material that appropriately reflects laser light so that the irradiation point can be identified visually or by an image sensor when irradiated with laser light. The light-receiving spheres 50 and 52 may be coated with, for example, fluorescent paint to make the irradiation point of the laser light clear. Note that if the measurement point is located in midair, a perfect sphere such as the light-receiving sphere 50 is used. On the other hand, if the measurement point is located on the ground surface, a hemisphere such as the light-receiving sphere 52 is used.

[0020] Next, the direction from which the light reaching the measurement point, i.e., the center of the light-receiving sphere, comes is measured (step 208). This measurement is performed, for example, by taking photographs from multiple directions. Laser light emitted from the light source is reflected by various elements contained in the scale model, so it may arrive at the measurement point from any direction.

[0021] In the comparative example described above, it is only possible to estimate the direction of arrival of the path to the receiving sphere from the directional light irradiated onto the receiving sphere, and there is a problem in that it is not possible to estimate the propagation distance, number of reflections, and reflection position of the path. In order to solve the above problem, the present disclosure aims to provide a propagation environment estimation method that can estimate the propagation distance, number of reflections, and reflection position of the path by filling a scale model with smoke and then scanning it with a directional light-emitting element that is regarded as a transmitter.

[0022] [Outline of the first embodiment] Fig. 3 is a perspective view of a scale model used in the propagation environment estimation method according to embodiment 1 of the present disclosure. Fig. 4 is a flowchart showing an outline of the propagation environment estimation method according to embodiment 1 of the present disclosure. As shown in Fig. 4, in the propagation environment estimation method according to embodiment 1, estimation of the propagation environment proceeds in the following procedure.

[0023] First, a scale model 10 is created at an arbitrary scale ratio for an indoor target area (step 102). In addition, paint is applied or mirror film is attached to the surfaces of the created scale model 10, such as walls, floors, ceilings, and objects, to produce specular reflection.

[0024] Next, a laser pointer 2, which is a directional light emitting element that is used for transmission, is placed (step 104).

[0025] Next, a receiving marker 4 is placed at the receiving position to represent reception (step 106).

[0026] Next, the smoke generator 6 is used to fill the inside of the scale model 10 with smoke (step 108). Dry ice, glycols, or the like are used for the smoke.

[0027] Next, the laser pointer 2 is scanned, and when the laser light is irradiated onto the receiving marker 4, the camera 8 photographs the path of the laser light (step 110). By filling the scale model with smoke, the light from the laser pointer 2 can be made visible, making it possible to photograph it. The camera 8 photographs through holes drilled in the walls, ceiling, and floor.

[0028] Next, the propagation distance, number of reflections, and reflection position of each path are derived from the results of the image taken in the previous step (step 112). For example, image recognition using images taken by the camera 8 is used for the derivation.

[0029] As described above, by filling a scale model with smoke and scanning it with a directional light-emitting element that acts as a transmitter, it is possible to estimate the propagation distance of a path, the number of reflections, and the reflection positions.

[0030] [Details of the procedure in the first embodiment] Fig. 5 is a flowchart illustrating in detail the steps of the propagation environment estimation method according to the first embodiment of the present disclosure. The steps illustrated in Fig. 5 are started when information collection for an existing target area, such as the dimensions and locations of buildings and roads, the radio wave reflectivity of key locations, and the radio wave frequency to be used, has been completed, and the specifications of the light source to be used for measurement, etc. have been determined.

[0031] As shown in Figure 5, this procedure first involves creating a scale model using a 3D printer (step 114). Here, the 3D printer is provided with information about the scale of the scale model to be created and information about the dimensions and locations of various structures and other structures in the target area. The 3D printer creates a scale model of the target area according to the provided scale.

[0032] Once the 3D printer processing is complete, the created scale model is then subjected to a reflective treatment (step 116). For example, the walls of the building model are painted or surface treated to match the reflectance of light to that of radio waves. The reflective treatment in this step may be performed manually by an operator. Alternatively, the painting process may be performed using a fully automated painting device that can specify the areas to be painted in three dimensions. Furthermore, the surface treatment may be achieved by processing using a 3D printer.

[0033] Next, a light source that resembles a radio wave transmitting station, specifically a laser pointer capable of three-dimensional scanning, is installed (step 118). The laser pointer 2 is installed at a candidate installation site for the transmitting station on the scale model. The installation of the laser pointer may be carried out manually by an operator, or may be carried out without human intervention by a fully automated element mounter.

[0034] Next, receiving markers are placed at the measurement points set in the scale model (step 120). The placement of the receiving markers may be performed manually by an operator, or may be performed by a fully automatic element mounter without human intervention.

[0035] Next, the interior of the scale model is filled with smoke by a smoke generation process (step 122). This process may be carried out manually by an operator, or may be carried out without human intervention by a fully automatic smoke generation device.

[0036] Once the above process is complete, scanning with the laser pointer begins (step 124). As the scanning direction of the laser pointer changes, various reflected lights are generated within the scale model in addition to direct light. At a certain scanning position, these lights may become laser light that illuminates the receiving marker. In step 124, the scanning direction of the laser pointer is changed manually or automatically, and the state in which the receiving marker is illuminated by laser light is searched for visually or by image processing.

[0037] If the occurrence of the above-mentioned condition is confirmed, the path of the laser light is photographed with a camera (step 126). The camera photographs are taken through holes drilled in the wall, ceiling, and floor. The camera photographs may be taken manually by an operator, or may be taken by a fully automatic photographing device without human intervention.

[0038] Next, the path of the laser light is estimated from the captured image (step 128). For example, the reflection position is derived by extracting refraction points from the captured image and detecting their positions. The number of refraction points is also detected to derive the number of reflections. Furthermore, the distance between a refraction point and other refraction points is detected to derive the propagation distance of the laser light path.

[0039] As described above, the propagation environment estimation method of this embodiment makes it possible to derive the propagation distance, number of reflections, and reflection positions of the path of laser light at a measurement point without installing multiple antennas or a large directional antenna in the scale model. The propagation information of the path of laser light derived in this manner accurately matches the propagation information of radio waves in an actual target area. Therefore, the method of this embodiment makes it possible to estimate the propagation information of radio waves at any measurement point in a target area simply and at low cost.

[0040] [Propagation environment estimation system according to the first embodiment] Fig. 6 is a block diagram showing the configuration of a propagation environment estimation system that performs a series of processes continuously and fully automatically according to the first embodiment of the present disclosure. The system shown in Fig. 6 includes a control device 30 and a storage device 32. The control device 30 includes an arithmetic processing unit. The storage device 32 stores a program to be executed by the arithmetic processing unit. The control device 30 controls each part of the system shown in Fig. 6 by the arithmetic processing unit performing processing in accordance with the program.

[0041] In addition to the above programs, the storage device 32 stores various information related to the target area. This information includes the dimensions, location, and radio wave reflectivity of buildings, roads, etc., as well as scale information for the scale model to be created. The storage device 32 also stores dimensional data for various elements that can be used in the scale model. Furthermore, the storage device 32 also stores the results of measurements performed using the scale model, i.e., information on the propagation distance, number of reflections, and reflection position obtained in the processing of step 114 above.

[0042] The system shown in Fig. 6 includes a 3D printer 34. The 3D printer 34 reads information about the target area and scale information for the scale model to be created from the storage device 32, and cuts out the scale model. If texture processing is required on a specific portion to match the reflectance of the radio waves and the measurement light, the 3D printer 34 also performs this processing.

[0043] The system shown in Fig. 6 includes a painting device 36. The painting device 36 is equipped with a paint nozzle that can move three-dimensionally, and can apply a desired paint to any position on the scale model. In response to commands from the control device 30 and based on information read from the memory device 32, the painting device 36 can apply paint to a specified position on the scale model to obtain a desired reflectance.

[0044] The system shown in Fig. 6 includes an element mounter 38. The element mounter 38 has the function of installing various elements, etc., that are planned to be used in the scale model, at any position on the scale model. In this embodiment, the laser pointer 2, which functions as a light source, and the receiving marker 4, which is installed at the measurement point, are installed by the element mounter 38 in accordance with commands from the control device 30.

[0045] The system shown in Fig. 6 includes a smoke generator 6. The smoke generator 6 has the function of emitting smoke such as dry ice or glycols. In this embodiment, the smoke generator 6 fills the interior of the scale model 10 with smoke in accordance with commands from the control device 30.

[0046] The system shown in Fig. 6 further includes an imaging device 40. The imaging device 40 has the function of capturing images of measurement points set in the scale model from multiple directions. In this embodiment, the imaging device 40 is configured to be able to capture images of the path of the laser light illuminating the receiving marker 4 from holes opened in the walls, ceiling, and floor of the scale model 10. The estimation process in step 128 above is executed by the control device 30 based on the data of the images captured by the imaging device 40.

[0047] The propagation environment estimation system shown in Fig. 6 can perform the series of steps shown in Fig. 5 in a seamless and fully automated manner. Therefore, this system can significantly improve the efficiency of the work of estimating radio wave propagation information in a target area using a scale model.

[0048] Embodiment 2 7 is a perspective view of a scale model used in a propagation environment estimation method according to Embodiment 2 of the present disclosure. The scale model according to Embodiment 2 differs from Embodiment 1 in that the target area is outdoors.

[0049] In the propagation environment estimation method according to the second embodiment, the propagation environment is estimated in the same procedure as in the flowchart of Fig. 4. Therefore, the following will describe the differences from the first embodiment.

[0050] First, in step 102, the target area for creating a scale model 12 at an arbitrary scale ratio is outdoors. Therefore, the scale model 12 does not have walls or a ceiling. As in the first embodiment, paint is applied or mirror film is attached to the surfaces of the created scale model 12, such as the floor and objects, to create a mirror-like reflection.

[0051] In step 108, when filling the scale model 12 with smoke, something heavier in density than air, such as dry ice, is used. This is to prevent the smoke from being diluted by diffusion, since the measurement is performed outdoors.

[0052] Furthermore, in step 110, since the measurement is performed outdoors, the camera 8 can take the photograph from any location.

[0053] As described above, by using smoke that has a higher specific gravity than air, it is possible to obtain the same effect as in the first embodiment even in an outdoor target area.

[0054] Embodiment 3 8 is a perspective view of a scale model used in a propagation environment estimation method according to Embodiment 3 of the present disclosure. The scale model according to Embodiment 3 differs from Embodiment 1 in that the floor, walls, and ceiling are half mirrors.

[0055] In the propagation environment estimation method according to the third embodiment, the propagation environment is estimated in the same procedure as in the flowchart of Fig. 4. Therefore, the following will describe the differences from the first embodiment.

[0056] First, in step 102, half mirrors are used on the floor, walls, and ceiling when fabricating the scale model 14. This achieves both the effect of reflecting the path of the laser light off the floor, walls, and ceiling, and the effect of making the inside of the scale model 14 visible from the outside. As in the first embodiment, paint is applied or mirror film is attached to the surfaces of the fabricated scale model 14, such as the floor and objects, to provide a mirror-like reflection.

[0057] In addition, in step 110, the light path of the laser pointer 2 is photographed through half mirrors installed on the floor, walls, and ceiling. As described in step 1, the installation of half mirrors makes it possible to always see the inside of the scale model from the outside. Therefore, unlike in embodiment 1, there is no need to prepare a hole for photography, and photography can be performed from any position.

[0058] As described above, by using a half mirror on the outer surface of the scale model, it is possible to obtain the same effect as in the first embodiment without providing a hole for photography. [Explanation of symbols]

[0059] 4 Receive Marker 6 Smoke Generator 8. Camera 10 scale model 12 scale model 14 scale model 30 Control device 38 Element mounter 40 Imaging equipment

Claims

1. A propagation environment estimation method for estimating a radio wave propagation environment using a scale model, comprising: A model making step to make a scale model; a light source installation step of installing a light source that emits directional light and can scan an irradiation direction on the scale model, the light source being likened to a radio wave transmitting station; a receiving marker installation step of installing a receiving marker representing a radio wave receiving station on the scale model; a smoke generating step of filling the scale model with smoke using a smoke generating device; a scanning step of scanning the light source through the scale model; an imaging step of imaging a path of light when the light is irradiated onto the receiving marker with a camera; an estimation step of estimating propagation information of the path from an image captured by the camera; A propagation environment estimation method including:

2. 2. The propagation environment estimation method according to claim 1, wherein the path propagation information is at least one of the propagation distance, the number of reflections, and the reflection position of the path.

3. The propagation environment estimation method according to claim 1 , further comprising the step of performing a reflection process on at least a part of the scale model so that the light reflectance of the scale model matches the radio wave reflectance of the target area.

4. the scale model comprises walls, a floor, and a ceiling with holes; The camera takes a photograph through the hole. The propagation environment estimation method according to any one of claims 1 to 3.

5. The smoke used in the smoke generation step has a physical property of being heavier in specific gravity than air, The camera takes pictures from any location. The propagation environment estimation method according to any one of claims 1 to 3.

6. The scale model has walls, a floor, and a ceiling made of half mirrors, The camera takes a photograph from an arbitrary location outside the scale model through the half mirror. The propagation environment estimation method according to any one of claims 1 to 3.

7. A propagation environment estimation system that estimates a radio wave propagation environment using a scale model, A 3D printer to create scale models, an element mounter that installs a light source and a receiving marker on the scale model; a smoke generator for filling the scale model with smoke; an imaging device that captures a path of light irradiated from the light source to the receiving marker; a control device that controls the 3D printer, the element mounter, the smoke generating device, and the photographing device; Equipped with The control device estimates propagation information of the path from the image acquired by the photographing. Propagation environment estimation system.

8. A propagation environment estimation device that estimates a radio wave propagation environment using a scale model, A 3D printer section for creating scale models, an element mounter unit that installs a light source and a receiving marker on the scale model; a smoke generator unit that fills the scale model with smoke; an imaging device unit that captures an image of a path of light irradiated from the light source to the receiving marker; a control device unit that controls the 3D printer unit, the element mounter unit, the smoke generator unit, and the photographing device unit; Equipped with The control device estimates propagation information of the path from the image acquired by the photographing. Propagation environment estimation device.

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