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

Abstract

The present disclosure relates to a propagation environment estimating method for estimating a propagation environment of radio waves by use of a scale model. This method comprises the following steps. A scale model is created (step 1), a light source is installed (step 2), the scale model is scanned with the light source 10, a center-light generation state in which center light directed toward a measurement point is generated is detected, and a reception sphere is installed with the center thereof aligned with the measurement point (step 3). Under the center-light generation state, one path is recognized for each of the positions of irradiation points appearing on the reception sphere, and the center-light search step and the irradiation point detection step are repeated so as to find all paths related to the measurement point (step 4). A radio path incoming degree α representative of the total intensity of light generated by all the paths is calculated, and the radio path incoming degree α is considered a characteristic value of the radio intensity at the measurement point (step 6).

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 device, and a propagation environment estimation system 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] The following Non-Patent Document 1 discloses a method for investigating radio wave reflection conditions using a scale model. Figure 1 is a schematic diagram that compares the process of estimating a propagation model through actual measurements in an actual area with the process of using a scale model to estimate the model through actual measurements.

[0005] As shown in Figure 1, in the scale modeling method, a scale model of an actual urban area is created at a scale of, for example, 1 / 100. Radio signals are then generated in the scale model environment, and the propagation characteristics of the radio waves are measured. This method can significantly reduce the cost of collecting the necessary data compared to measuring the propagation environment in an actual urban area. [Prior art documents] [Non-patent literature]

[0006] [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. https: / / ieeexplore.ieee.org / abstract / document / 5633222 Summary of the Invention [Problem to be solved by the invention]

[0007] In urban areas where various buildings coexist, radio waves emitted from a transmitting station are repeatedly reflected, so the direction from which the radio waves arrive at each point within the area varies. For this reason, when launching a new communication service, it is important to estimate the direction from which radio waves will arrive at each point in the target area.

[0008] In conventional methods using scale models, the propagation environment is generally estimated by actually measuring the behavior of radio waves in the 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.

[0009] However, installing multiple antennas at each measurement point on a scale model requires significant costs and labor. Furthermore, antennas with sharp directivity are generally large and difficult to fit within a scale model. Therefore, when using a scale model to estimate the radio wave propagation environment, it is desirable to use an alternative method that estimates the direction of arrival of radio waves easily and at low cost without installing antennas. Furthermore, installing antennas on a scale model allows the strength of radio waves reaching the antenna to be measured and the communication capacity and communication speed at the measurement point to be determined based on the measurement results. However, without using antennas, it is not possible to directly measure radio wave strength. Therefore, with methods that do not use antennas, it is not possible to determine communication capacity, etc. from radio wave strength.

[0010] The present disclosure has been made in consideration of the above-mentioned problems, and has as a first object to provide a propagation environment estimation method for estimating radio wave propagation characteristics using a scale model, by which radio wave intensity at any measurement point can be estimated in a simple manner without using an antenna.

[0011] A second object of the present disclosure is to provide a propagation environment estimation system that estimates radio wave strength at any measurement point using a simple method without using an antenna when estimating radio wave propagation characteristics using a scale model.

[0012] Furthermore, a third object of the present disclosure is to provide a propagation environment estimation device that estimates radio wave strength at any measurement point using a simple method without using an antenna when estimating radio wave propagation characteristics using a scale model. [Means for solving the problem]

[0013] In order to achieve the above object, a first aspect is 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 scanning step of scanning the light source through the scale model; a central light searching step of detecting a central light generation state in which a central light is generated toward a measurement point set in the scale model during the scanning process; an irradiation point detection step of detecting the position of an irradiation point that appears under the central light generation state on a receiving sphere that is installed so that its center coincides with the measurement point; identifying one path for each location of the illumination point and repeating the center light search step and the illumination point detection step to find all paths related to the measurement point; an α calculation step of calculating a radio wave path arrival degree α that represents the total intensity of light generated by all the paths; a step of setting the radio wave path arrival degree α as a characteristic value of radio wave intensity at a measurement point on a target area corresponding to the measurement point; It is desirable to include:

[0014] A second aspect is a propagation environment estimation system that estimates a radio wave propagation environment using a scale model, 3D printers to create scale models, an element mounter for mounting a light source that emits directional light and can scan the irradiation direction on the scale model, likening it to a radio wave transmitting station; a control device that controls the 3D printer and the element mounter; The control device a scanning process for scanning the scale model with the light source; a central light search process for detecting a central light generation state in which a central light is generated toward a measurement point set in the scale model during the scanning process; an irradiation point detection process for detecting the position of an irradiation point that appears under the central light generation state on a receiving sphere that is installed so that its center coincides with the measurement point; a process of identifying one path for each position of the irradiation point and repeating the central light search process and the irradiation point detection process to find all paths related to the measurement point; an α calculation process for calculating a radio wave path arrival degree α that represents the total intensity of light generated by all the paths; A process of setting the radio wave path arrival degree α as a characteristic value of radio wave intensity at a measurement point on a target area corresponding to the measurement point; It is preferable that the method is further configured to execute the following.

[0015] A third aspect is a propagation environment estimation device that estimates a radio wave propagation environment using a scale model, 3D printer section for creating scale models, an element mounter unit for mounting a light source on the scale model, which emits directional light and is capable of scanning the irradiation direction, in the manner of a radio wave transmitting station; A control device unit that controls the 3D printer unit and the element mounter unit, The control device unit a scanning process for scanning the scale model with the light source; a central light search process for detecting a central light generation state in which a central light is generated toward a measurement point set in the scale model during the scanning process; an irradiation point detection process for detecting the position of an irradiation point that appears under the central light generation state on a receiving sphere that is installed so that its center coincides with the measurement point; a process of identifying one path for each position of the irradiation point and repeating the central light search process and the irradiation point detection process to find all paths related to the measurement point; an α calculation process for calculating a radio wave path arrival degree α that represents the total intensity of light generated by all the paths; A process of setting the radio wave path arrival degree α as a characteristic value of radio wave intensity at a measurement point on a target area corresponding to the measurement point; It is preferable that the method is further configured to execute the following. [Effects of the Invention]

[0016] According to the first to third aspects, when estimating the propagation characteristics of radio waves using a scale model, the radio wave intensity at any measurement point can be estimated by a simple method without using an antenna. [Brief explanation of the drawings]

[0017] [Figure 1] This is a schematic diagram showing a comparison between estimating a propagation model through actual measurements in an actual area and estimating a model through actual measurements using a scale model. [Figure 2] FIG. 2 is a diagram illustrating a processing flow when estimating the direction of arrival of radio waves using the propagation environment estimation method according to the first embodiment of the present disclosure. [Figure 3] 1 is a diagram for explaining the concept of a radio wave path arrival degree α required to implement a propagation environment estimation method according to a first embodiment of the present disclosure. [Figure 4] Four examples of the calculation formula for the radio wave path arrival degree α are shown below. [Figure 5] 1 is a development diagram of an actual measurement environment for measuring actual measurement data required to implement a propagation environment estimation method according to a first embodiment of the present disclosure. [Figure 6] Figure 5 shows an experiment scene using a scale model that corresponds to the actual measurement environment. [Figure 7] FIG. 2 is a diagram for explaining a method for calculating a communication capacity ratio R required to implement the propagation environment estimation method according to the first embodiment of the present disclosure. [Figure 8]FIG. 2 is a diagram for explaining a processing flow when estimating a communication capacity at a measurement point by the propagation environment estimation method according to the first embodiment of the present disclosure. [Figure 9] 1 is a diagram illustrating a comparison between the estimated results of communication capacity measured by the propagation environment estimation method according to the first embodiment of the present disclosure and the results of actual measurement. [Figure 10] FIG. 9 is a block diagram for explaining the configuration of a propagation environment estimation system that performs the series of processes shown in FIG. 8 continuously and fully automatically. [Figure 11] 11 is a flowchart illustrating the flow of processing executed in the transmission environment estimation system shown in FIG. 10. [Figure 12] 11 is a flowchart illustrating the flow of processing executed in the transmission environment estimation system shown in FIG. 10. DETAILED DESCRIPTION OF THE INVENTION

[0018] Embodiment 1 [Outline of the first embodiment] 2 is a diagram illustrating a processing flow when estimating the direction of arrival of radio waves using the propagation environment estimation method according to the first embodiment of the present disclosure. More specifically, the upper part of FIG. 2 shows a perspective view of a scale model used in the propagation environment estimation method according to this embodiment. Even more specifically, the left side of the upper part of FIG. 2 shows a case where a hollow point on the scale model is set as the measurement point of radio waves. Furthermore, the right side of the upper part of FIG. 2 shows a case where a point on the ground surface on the scale model is set as the measurement point of radio waves.

[0019] The lower part of Fig. 2 shows a flowchart for explaining the flow when estimating the direction of arrival of radio waves using the propagation environment estimation method of this embodiment. The numbers "1," "2," "3," and "4" shown in the upper part of Fig. 2 correspond to the numbers of each step shown in the lower part of Fig. 2, respectively.

[0020] The propagation environment estimation method of this embodiment can be used as a technique for investigating in advance the propagation characteristics of wireless signals in a service area when starting a new wireless communication service, etc. A service area is typically assumed to be an urban area with many buildings or an indoor space inside a building.

[0021] As shown in FIG. 2, in the method of this embodiment, the direction of arrival of the radio wave is estimated in the following procedure. 1. Create a model of the target area. 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. Figure 2 shows an example in which an outdoor space is used as the target area, but the interior of a specific building may also be used as the target area.

[0022] 2. A light source is installed to act as a radio wave transmission source. A laser pointer or similar device that emits a laser beam with excellent linearity is used as the light source. The light source is configured so that the direction of the laser beam can be scanned three-dimensionally.

[0023] 3. The receiving sphere is placed so that the measurement point set on the scale model is at its center. The receiving sphere is made of a material that appropriately reflects laser light so that the irradiation point can be identified visually or by an image sensor when the laser light is irradiated. The receiving sphere may be coated with, for example, fluorescent paint to make the irradiation point of the laser light clear. If the measurement point is in midair, a perfect sphere is used as the receiving sphere. On the other hand, if the measurement point is on the ground surface, a hemisphere is used as the receiving sphere.

[0024] 4. Next, measure the direction from which the light reaching the measurement point, i.e., the center of the receiving sphere, comes. Hereafter, this light will be referred to as the "center light." The 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.

[0025] Here, first, the scanning position of the laser light that generates the central light is searched for. For example, a light-receiving target is placed at the measurement point on the scale model, that is, the point where the arrival direction of the radio waves is to be estimated. In this state, scanning is performed with the laser light to find the state where the light-receiving target is illuminated. Since the light that illuminates the light-receiving target is the "central light," the scanning position that illuminates the light-receiving target can be recognized as the scanning position that generates the central light.

[0026] Once the scanning position that generates the central light is found, a receiving sphere is placed in place of the light-receiving target. At this time, the receiving sphere is placed so that its center coincides with the measurement point. Under this condition, when a central light is generated using the above scanning position, the surface of the receiving sphere is illuminated with light directed toward the center of the receiving sphere. Then, by connecting the illuminated point that appears on the surface of the receiving sphere with the center of the receiving sphere, i.e., the measurement point, the direction of arrival of the light reaching the illuminated point can be detected.

[0027] [Features of the first embodiment] As described above, the propagation environment estimation method of this embodiment makes it possible to estimate the direction of arrival of light reaching a measurement point, i.e., the direction of arrival of radio waves reaching a measurement point in a target area, without placing an antenna in the scale model. However, because this method does not place an antenna in the scale model, it is not possible to directly measure the strength of radio waves reaching a measurement point on the scale model.

[0028] 3 is a diagram illustrating the concept of the radio wave path arrival degree α used in this embodiment to estimate the radio wave intensity arriving at a measurement point in a scale model. By using the radio wave path arrival degree α, it becomes possible to estimate the radio wave intensity at any measurement point in the scale model without using an antenna, as will be explained below.

[0029] Specifically, Figure 3 shows a top view of a receiving sphere 10 installed on a scale model. The receiving sphere 10 is divided into M parts based on direction. Specifically, Figure 3 shows an example where M=4, i.e., the receiving sphere 10 is divided into four parts based on direction.

[0030] Illumination from the light source may reach the receiving sphere 10, which is installed at the measurement point of the scale model, from various directions by being reflected at various locations. Hereinafter, each individual path of light that reaches the receiving sphere 10 will be referred to as a "path." In Figure 3, each circle shown inside the receiving sphere 10 represents each path that reaches the receiving sphere 10.

[0031] In Figure 3, pm,n shown along the circles indicates the number of reflections experienced by the m,nth path. Here, m,n indicates that the path arrived from the mth direction out of M divided directions, and that the path is the nth path included in the mth divided direction. According to this definition, the number of reflections of multiple paths arriving at the receiving sphere 10 from all directions can be handled separately.

[0032] Figure 4 shows four examples of formulas for calculating the radio wave path arrival degree α of the receiving sphere 10. Each formula can be used depending on the characteristics of the target area whose propagation environment is to be estimated. Furthermore, these formulas may be used depending on the characteristics of each measurement point within the target area.

[0033] In the equations shown in Figure 4, Π is a symbol meaning the sum of factors, and Σ is a symbol meaning the sum of factors. Also, r is the reflection coefficient at a reflection point in the scale model. In this embodiment, for simplicity, the reflection coefficient r is assumed to be the same value at all points.

[0034] The formula shown at the top of Figure 4 represents the following summation: α=(1+r p1,1 )·(1+r p1,2 )... (1+r p4,N4 ) For example, the first term (1+r p1,1) will have a maximum value of "2" if the 1,1th path is direct light, that is, if the number of reflections p1,1 = 0, and will approach a minimum value of "1" as the number of reflections p1,1 increases. In other words, in this calculation formula, the more paths that reach the receiving sphere 10, the more times the factors, each of which is "1 or greater," are multiplied. As a result, the calculation result α will have a larger value as the number of paths increases. Furthermore, in this calculation formula, the fewer the number of reflections, the greater the weighting given to each individual path. Therefore, the calculation result of α is the total strength of all paths when direct waves are emphasized.

[0035] The calculation formula shown at the bottom of Figure 4 represents the summation as follows: α=1+r p1,1 +r p1,2 +···Omitted···r p4,N4 This calculation formula takes a larger value as the number of paths that reach the receiving sphere 10 increases. However, each factor is not multiplied by the other factors, but is simply added individually. Therefore, unlike the calculation formula shown at the top, the intensity of each path (number of reflections) does not function as a weighting factor. Therefore, according to this calculation formula, whether the wave is a direct wave or a reflected wave is not given importance, and α becomes a value that simply represents the overall intensity of the light that reaches the receiving sphere 10.

[0036] The other two equations shown in Figure 4 also have different characteristics. Although detailed explanations are omitted, the characteristics of the four equations shown in Figure 4 change from emphasizing direct waves to not emphasizing direct waves, starting from the top. Each equation provides the total strength of all paths that reach the receiving sphere 10 as the radio wave path arrival degree α.

[0037] According to the propagation environment estimation method of this embodiment, it is possible to find the state in which light arrives at a measurement point on a scale model using the procedure described with reference to FIG. 2 . Then, the path that the light follows in each state can be detected visually or by image processing. That is, according to the propagation environment estimation method of this embodiment, it is possible to find all paths that arrive at each measurement point and to detect where and how each path is reflected. Once this information is known, it is possible to calculate the radio wave path arrival degree α, which represents the total strength of all paths, for each measurement point using the procedure described with reference to FIGS. 3 and 4 . The propagation environment estimation method of this embodiment is characterized in that it enables estimation of the radio wave strength at any measurement point, as well as estimation of communication capacity, etc., without placing an antenna in the scale model, by using the radio wave path arrival degree α calculated in this manner.

[0038] [Example of communication capacity estimation] The actual communication capacity (channel capacity or Shannon capacity) in a target area is not determined solely by the strength of radio waves arriving at a measurement point. Specifically, the communication capacity varies depending on, for example, the SNR (Signal Noise Rate) at the measurement point. For this reason, even if the radio wave path arrival degree α can be estimated, it is difficult to estimate the communication capacity and the like from that value alone. Therefore, in this embodiment, a small number of actual measurements are performed in the target area, and the results are combined with measurements using a scale model, making it possible to estimate the communication capacity at any measurement point.

[0039] Fig. 5 shows an example of an actual measurement environment used in this embodiment. Specifically, Fig. 5 shows an indoor space with a width of 7.5 m, a depth of 6.2 m, and a height of 2.6 m as the target area for propagation environment estimation. Two windows, each 1.2 m high and 2.65 m and 1.70 m wide, are installed on one wall. A whiteboard and partitions are installed in the indoor space, and measurement points #1 to #64 are set.

[0040] An antenna can be installed at each of measurement points #1 to #64. At the measurement points where an antenna is installed, communication capacity (channel capacity or Shannon capacity) and SNR can be measured. Although it is possible to measure communication capacity and the like at all of measurement points #1 to #64, in this embodiment, in order to reduce the measurement load, measurements are performed by focusing on several reference points. As an example, here, communication capacity and SNR are measured using six diagonally arranged measurement points #1, #19, #28, #37, #46, and #64 as reference points.

[0041] Figure 6 shows an experimental scene in a scale model that mimics the target area shown in Figure 5. As shown in Figure 6, the scale model is provided with windows and partitions to mimic the target area. In the scale model, the above measurements using receiving sphere 10 are performed at all measurement points for which communication capacity estimation is desired, including the above reference points #1, #19, #28, #37, #46, and #64.

[0042] Fig. 7 is a diagram for explaining a calculation method of the communication capacity ratio R used in the propagation environment estimation method of the first embodiment. The broken "measured" line in Fig. 7 indicates the communication capacity value actually measured at the reference point in the target area. Furthermore, "α x SNR" indicated by the dashed line in Fig. 7 is a plot of the multiplication value of (radio wave path arrival degree α) and (actually measured SNR value) at six reference points. Here, α is calculated from path information measured for each reference point using a scale model. Furthermore, the actual SNR value is a value actually measured at the reference point in the target area.

[0043] Since α for each reference point is the total strength of all paths that reach the reference point on the scale model, it should correlate with the radio wave strength at the reference point on the target area. Furthermore, since communication capacity is primarily determined by radio wave strength and SNR, the value of α×SNR should correlate with the actually measured communication capacity. Therefore, in this embodiment, the correlation between the "actually measured" communication capacity and "α×SNR" is calculated as the "communication capacity ratio R" using the following method.

[0044] (1) The average value of the communication capacity actually measured at six reference points #1, #19, #28, #37, #46 and #64 on the target model is calculated. (2) Calculate the radio wave path arrival degree α for each of the six reference points #1, #19, #28, #37, #46, and #64 on the scale model. (3) The SNRs actually measured at six reference points #1, #19, #28, #37, #46 and #64 on the target model are multiplied by the corresponding radio wave path arrival degrees α. (4) Calculate the average value of the six obtained "α × SNR". (5) The ratio of the average value calculated in (1) above to the average value calculated in (4) above is defined as the "communication capacity ratio R."

[0045] The "Estimate (=α×SNR×R)" shown by the solid line in Fig. 7 is a plot of the value obtained by multiplying the above "α×SNR" for each reference point by the communication capacity ratio R. Theoretically, the "Estimate (=α×SNR×R)" calculated in this way should approximate the communication capacity for each reference point, and in fact, as shown in Fig. 7, it is close to the actually measured value of communication capacity.

[0046] As described above, by actually measuring the communication capacity and SNR at several reference points, the communication capacity ratio R can be determined. Once the communication capacity ratio R can be determined, it becomes possible to estimate the communication capacity at any measurement point for which the radio wave path arrival degree α and SNR are known. The radio wave path arrival degree α can be calculated using a scale model as described above. Therefore, according to this embodiment, once the SNR can be obtained, the communication capacity at any measurement point can be estimated. The SNR at any point may be obtained by actual measurement, but it can also be estimated by statistically processing data obtained in the past, for example. Therefore, according to this embodiment, the communication capacity at any measurement point can be easily estimated with only a small amount of actual measurement work.

[0047] 8 is a diagram for explaining the processing flow when estimating the communication capacity of an arbitrary measurement point by the propagation environment estimation method of this embodiment. As shown in Fig. 8, in the method of this embodiment, the arrival direction of radio waves is estimated in the following procedure.

[0048] 1 to 4. Measurements are taken on the scale model according to the procedure explained with reference to Figure 2. Specifically, the following processing is carried out for each measurement point. (1) Scan to find all paths. (2) Measure the direction of arrival of each path. (3) Measure the number of reflections for each path.

[0049] 5. Perform the following measurements in the actual environment of the target area. (1) Measure the communication capacity at several predetermined reference points. (2) Measure the SNR at the above reference points.

[0050] 6. Estimate the communication capacity for any measurement point. Specifically, perform the following process. (1) Calculate the radio wave path arrival degree α for the above reference point on the scale model. (2) A communication capacity ratio R is calculated based on the average value of the actually measured communication capacity and the average value of α×SNR. (3) Obtain the SNR at any measurement point (actually measured or estimated). (4) Calculate the radio wave path arrival degree α for any measurement point. (5) For any measurement point, estimate the communication capacity by α×SNR×R.

[0051] 9 is a diagram comparing the estimated communication capacity (solid line) calculated for 64 measurement points using the method of this embodiment with the communication capacity actually measured at those 64 points (dashed line). As shown in FIG. 9, a strong correlation is observed between the estimated value indicated by the solid line and the actual measurement value indicated by the dashed line. Thus, the method of this embodiment makes it possible to accurately estimate the communication capacity at any measurement point using a simple method.

[0052] [Propagation environment estimation system according to the first embodiment] Fig. 10 is a block diagram for explaining the configuration of a propagation environment estimation system that can continuously and fully automatically carry out the series of processes shown in Fig. 8. The system shown in Fig. 10 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. 10 by the arithmetic processing unit carrying out processing in accordance with the program.

[0053] 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 reflection coefficient of buildings, roads, etc. The storage device 32 also stores dimensional data for various elements that can be used in the scale model. The storage device 32 also stores the results of measurements performed using the scale model, i.e., information on all paths obtained by the processing of steps 1 to 4 shown in FIG. 8. The storage device 32 may also store the results of surveys conducted in the past. The SNR at any measurement point may then be statistically estimated from the past results depending on the dimensions and characteristics of the target area.

[0054] The system shown in Fig. 10 includes a 3D printer 34. The control device 30 reads various information from the storage device 32 and performs a process to determine the scale. The 3D printer reads information about the target area from the storage device 32 and carves out a scale model at the scale determined by the control device 30. If texture processing is required on a specific portion to align the reflection coefficients of the radio waves and the measurement light, this processing is also performed by the 3D printer 34.

[0055] The system shown in Fig. 10 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 reflection coefficient.

[0056] The system shown in Figure 10 includes an element mounter 38. The element mounter 38 has the function of installing various elements, etc., planned for use in the scale model, at any position on the scale model. In this embodiment, a laser pointer, which functions as a light source, and a receiving sphere 10, which is installed at the measurement point, are installed by the element mounter 38 in accordance with commands from the control device 30.

[0057] The system shown in Fig. 10 further includes an image capture device 40. The image capture device 40 has the function of capturing images of a measurement point set in the scale model from multiple directions. More specifically, the image capture device 40 is configured to capture images of the light-receiving target and the receiving sphere 10 from all directions. The search for the central light and the estimation of the direction of arrival are both performed based on the data of the images captured by the image capture device 40.

[0058] The propagation environment estimation system shown in Fig. 10 can perform the series of steps shown in Fig. 8 in a seamless and fully automated manner. Therefore, this system can significantly improve the efficiency of the task of estimating the direction of arrival of radio waves in a target area using a scale model.

[0059] The process from setting the scale to estimating information about all paths, that is, the series of processes executed by the propagation environment estimation system corresponding to steps 1 to 4 shown in Fig. 8, can be divided and represented as shown in the flowchart of Fig. 11. Furthermore, the process from reading the communication capacity obtained in the actual measurement environment to estimating the communication capacity at an arbitrary measurement point, that is, the series of processes executed by the propagation environment estimation system corresponding to steps 5 to 6 shown in Fig. 8, can be divided and represented as shown in the flowchart of Fig. 12. The contents of each step have already been explained, so a repeated explanation thereof will be omitted here.

[0060] [Modification of the first embodiment] In the first embodiment described above, a light-receiving target is placed on the scale model, the central light is searched for, and then the receiving sphere 10 is placed on the scale model. However, the method for illuminating the receiving sphere 10 with the central light is not limited to this. For example, two identical scale models may be prepared, one with the receiving sphere 10 placed on it and the other with the light-receiving target placed on it, and both may be scanned by the light source in the same way. In this case, when the light-receiving target is irradiated, the receiving sphere 10 will inevitably be illuminated by the central light.

[0061] In addition, in this embodiment, the configuration shown in Fig. 10 is realized as a system consisting of multiple devices, but the present disclosure is not limited to this. That is, the configuration shown in Fig. 10 may be realized as a single device in which the illustrated elements are housed in a single housing. [Explanation of symbols]

[0062] 10 Receiving Sphere 30 Control device 32 Storage device 34 3D printer 36 Painting equipment 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 scanning step of scanning the light source through the scale model; a central light searching step of detecting a central light generation state in which a central light is generated toward a measurement point set in the scale model during the scanning process; an irradiation point detection step of detecting the position of an irradiation point that appears under the central light generation state on a receiving sphere that is installed so that its center coincides with the measurement point; identifying one path for each location of the illumination point and repeating the center light search step and the illumination point detection step to find all paths related to the measurement point; an α calculation step of calculating a radio wave path arrival degree α that represents the total intensity of light generated by all the paths; a step of setting the radio wave path arrival degree α as a characteristic value of radio wave intensity at a measurement point on a target area corresponding to the measurement point; A propagation environment estimation method including:

2. The α calculation step measuring the number p of reflections that occur in a process from the light source to the irradiation point for each path included in the total number of paths; reading out a reflection coefficient r at a location where the reflection occurs; The intensity of each path included in all the paths is expressed as the p-th power of r=r ｐ and calculating based on calculating the radio wave path arrival degree α by integrating the strength of each path; The propagation environment estimation method according to claim 1 , comprising:

3. m=1 to M is the direction of arrival of the path, n=1 to Nm is the path number in the m-th divided arrival direction, p m,n is the number of reflections of the n-th path in the m-th divided direction of arrival, 3. The propagation environment estimation method according to claim 2, wherein the α calculation step calculates the degree of arrival α of the radio wave path by using one of the following four arithmetic expressions:

4. a measuring step of measuring a communication capacity and an SNR at a reference point on the target area; a reference point α calculation step of calculating the radio wave path arrival degree α for a reference point on the scale model corresponding to the reference point; multiplying the SNR actually measured in the measurement step by the radio wave path arrival degree α calculated in the reference point α calculation step to obtain (α×SNR); calculating a communication capacity ratio R based on the actual measurement value of the communication capacity and the (α×SNR); acquiring an SNR at the measurement point; estimating a communication capacity at the measurement point based on the radio wave path arrival degree α at the measurement point, the SNR acquired for the measurement point, and the communication capacity ratio R; 4. The propagation environment estimation method according to claim 1, further comprising:

5. 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 for mounting a light source that emits directional light and can scan the irradiation direction on the scale model, likening it to a radio wave transmitting station; a control device that controls the 3D printer and the element mounter, The control device a scanning process for scanning the scale model with the light source; a central light search process for detecting a central light generation state in which a central light is generated toward a measurement point set in the scale model during the scanning process; an irradiation point detection process for detecting the position of an irradiation point that appears under the central light generation state on a receiving sphere that is installed so that its center coincides with the measurement point; a process of identifying one path for each position of the irradiation point and repeating the central light search process and the irradiation point detection process to find all paths related to the measurement point; an α calculation process for calculating a radio wave path arrival degree α that represents the total intensity of light generated by all the paths; A process of setting the radio wave path arrival degree α as a characteristic value of radio wave intensity at a measurement point on a target area corresponding to the measurement point; A propagation environment estimation system configured to further execute the above.

6. The control device an actual measurement value reading process for reading communication capacity and SNR actually measured at a reference point on the target area; a reference point α calculation process for calculating the radio wave path arrival degree α for a reference point on the scale model corresponding to the reference point; A process of multiplying the SNR acquired in the actual measurement value reading process by the radio wave path arrival degree α calculated in the reference point α calculation process to obtain (α×SNR); A process of calculating a communication capacity ratio R based on the actual measurement value of the communication capacity and the (α×SNR); A process of acquiring an SNR at the measurement point; a process of estimating a communication capacity at the measurement point based on the radio wave path arrival degree α at the measurement point, the SNR acquired for the measurement point, and the communication capacity ratio R; The propagation environment estimation system according to claim 5 , further configured to execute the following:

7. A propagation environment estimation device that estimates a radio wave propagation environment using a scale model, 3D printer section for creating scale models, an element mounter unit for mounting a light source on the scale model, which emits directional light and is capable of scanning the irradiation direction, in the manner of a radio wave transmitting station; A control device unit that controls the 3D printer unit and the element mounter unit, The control device unit a scanning process for scanning the scale model with the light source; a central light search process for detecting a central light generation state in which a central light is generated toward a measurement point set in the scale model during the scanning process; an irradiation point detection process for detecting the position of an irradiation point that appears under the central light generation state on a receiving sphere that is installed so that its center coincides with the measurement point; a process of identifying one path for each position of the irradiation point and repeating the central light search process and the irradiation point detection process to find all paths related to the measurement point; an α calculation process for calculating a radio wave path arrival degree α that represents the total intensity of light generated by all the paths; A process of setting the radio wave path arrival degree α as a characteristic value of radio wave intensity at a measurement point on a target area corresponding to the measurement point; The propagation environment estimation device is configured to further execute the above.

8. The control device unit an actual measurement value reading process for reading communication capacity and SNR actually measured at a reference point on the target area; a reference point α calculation process for calculating the radio wave path arrival degree α for a reference point on the scale model corresponding to the reference point; A process of multiplying the SNR acquired in the actual measurement value reading process by the radio wave path arrival degree α calculated in the reference point α calculation process to obtain (α×SNR); A process of calculating a communication capacity ratio R based on the actual measurement value of the communication capacity and the (α×SNR); A process of acquiring an SNR at the measurement point; a process of estimating a communication capacity at the measurement point based on the radio wave path arrival degree α at the measurement point, the SNR acquired for the measurement point, and the communication capacity ratio R; The propagation environment estimation device according to claim 7 , further configured to execute the following:

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