Diffraction loss analysis device, diffraction loss analysis method, and program

Abstract

This diffraction loss analysis device calculates, using a diffraction loss calculation formula, an estimated value of the diffraction loss of a radio communication path on the basis of terrain data indicating the ground surface corresponding to the radio communication path between the installation location of a transmission-side antenna and the installation location of a reception-side antenna. The diffraction loss analysis device generates a roundness loss estimation model that estimates roundness loss in accordance with the cross-sectional roundness in the direction of the radio communication path on the ground surface indicated by the terrain data, on the basis of the relationship between the estimated value of the diffraction loss and the diffraction loss calculation formula, and the measured value of the diffraction loss.

Description

[Technical Field]

[0001] The present disclosure relates to a diffraction loss analysis device and a diffraction loss analysis method for analyzing the diffraction loss of radio waves. program Regarding. [Background technology]

[0002] There is a technology for over-the-horizon radio wave communication where direct waves cannot reach the transmitting and receiving points separated by mountainous regions, etc. In such technology, the transmitting antenna at the transmitting point and the receiving antenna at the receiving point are often oriented directly opposite each other, with each antenna facing near the peak of the mountainous region. The transmitting and receiving antennas used for this radio wave communication have large diameters and use high-output power amplifiers. Radio wave communication beyond the line of sight is sometimes called over-the-horizon communication (OH communication). Radio wave diffraction loss must be calculated during circuit design work, which requires understanding propagation loss and other factors along the radio wave communication path between the installation location of the transmitting antenna and the installation location of the receiving antenna where OH communication is conducted.

[0003] A related technique is disclosed in Patent Document 1. Patent Document 1 discloses a technique for determining a representative diffraction point for a building and calculating the amount of loss in a radio wave propagation path using a knife-edge diffraction model. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2013-058929 Summary of the Invention [Problem to be solved by the invention]

[0005] It is necessary to analyze with high accuracy the diffraction loss, which is one type of propagation loss in the radio wave communication path between the installation position of the transmitting antenna and the installation position of the receiving antenna, where communication takes place.

[0006] An example of the object of this disclosure is to provide a diffraction loss analysis device and a diffraction loss analysis method that solve the above-mentioned problems. program The purpose is to provide [Means for solving the problem]

[0007] According to a first aspect of the present disclosure, a diffraction loss analysis device includes: an estimate calculation means that calculates an estimate of a diffraction loss of a radio wave communication path between an installation position of a transmitting antenna and an installation position of a receiving antenna, using the diffraction loss calculation formula, based on topographical data that indicates the earth's surface corresponding to the radio wave communication path; and a model generation means that generates a roundness loss estimation model that estimates a roundness loss corresponding to the roundness of a cross section of the earth's surface that is indicated by the topographical data, in the direction of the radio wave communication path, based on a relationship between the estimated diffraction loss, the diffraction loss calculation formula, and an actual measurement value of the diffraction loss.

[0008] According to a second aspect of the present disclosure, a diffraction loss analysis method includes: calculating an estimate of a diffraction loss of a radio wave communication path between an installation position of a transmitting antenna and an installation position of a receiving antenna, using the diffraction loss calculation formula, based on topographical data indicating the earth's surface corresponding to the radio wave communication path; and generating a roundness loss estimation model that estimates a roundness loss corresponding to the roundness of a cross section of the earth's surface indicated by the topographical data in the direction of the radio wave communication path, based on a relationship between the estimated diffraction loss, the diffraction loss calculation formula, and an actual measurement value of the diffraction loss.

[0009] According to a third aspect of the present disclosure, a recording medium stores a program that causes a computer of a diffraction loss analysis device to calculate, using the diffraction loss calculation formula, an estimated value of diffraction loss of a radio wave communication path between an installation position of a transmitting antenna and an installation position of a receiving antenna, based on topographical data that indicates the earth's surface corresponding to the radio wave communication path; and generate a roundness loss estimation model that estimates a roundness loss corresponding to the roundness of a cross section of the earth's surface that is indicated by the topographical data and that is in the direction of the radio wave communication path, based on a relationship between the estimated diffraction loss, the diffraction loss calculation formula, and an actual measurement value of the diffraction loss. [Effects of the Invention]

[0010] According to the present disclosure, it is possible to obtain a calculation formula for analyzing with high precision the diffraction loss, which is one type of propagation loss in a radio wave communication path between the installation position of a transmitting antenna and the installation position of a receiving antenna. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a diagram showing the configuration of a radio wave communication system having a radio wave communication path for which a diffraction loss analyzing apparatus according to an embodiment of the present invention estimates diffraction loss; [Figure 2] FIG. 1 is a hardware configuration diagram of a diffraction loss analysis device according to an embodiment of the present invention. [Figure 3] FIG. 1 is a functional block diagram of a diffraction loss analysis device according to an embodiment of the present invention. [Figure 4] FIG. 1 is a diagram showing an outline of processing performed by a diffraction loss analysis apparatus according to an embodiment of the present invention. [Figure 5] FIG. 10 is a diagram illustrating parameters used in a calculation formula for roundness loss according to the present embodiment. [Figure 6] FIG. 4 is a diagram showing a processing flow of the diffraction loss analysis apparatus according to the present embodiment. [Figure 7] FIG. 1 is a diagram illustrating an example of the configuration of a diffraction loss analysis device according to an embodiment of the present invention. [Figure 8] FIG. 8 is a diagram showing a processing flow by the diffraction loss analysis device shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0012] A diffraction loss analysis device for a radio wave communication system according to an embodiment of the present disclosure will be described below with reference to the drawings. Fig. 1 is a diagram showing the configuration of a radio wave communication system having a radio wave communication path for which a diffraction loss analysis device according to this embodiment estimates diffraction loss. As shown in Fig. 1, the radio wave communication system 100 has wireless communication equipment, each composed of an antenna and a wireless control device, at points A and B separated by a mountainous region or the like. A first wireless equipment at point A is equipped with an antenna 10 and a wireless control device 11. A second wireless equipment at point B is equipped with an antenna 20 and a wireless control device 21. The diffraction loss analysis device 1 may be communicatively connected to the wireless control device 11 and the wireless control device 21.

[0013] When one of antennas 10 and 20 transmits radio waves, the other of antennas 10 and 20 receives diffracted or reflected waves from obstacles such as mountainous regions. This results in OH communication, which is radio communication with no line of sight, between antennas 10 and 20. Radio control device 11 controls the signal amplification and output power of antenna 10, the transmission and reception direction of the transmitted radio waves, etc. Radio control device 21 controls the signal amplification and output power of antenna 20, the transmission and reception direction of the transmitted radio waves, etc. Diffraction loss analysis device 1 is a computer device provided to assist in line design according to the arbitrary installation positions of antennas 10 and 20, and identifies an equation to use for the diffraction loss of the radio wave communication path between a transmitting antenna and a receiving antenna, such as antenna 10 or antenna 20.

[0014] Specifically, the diffraction loss analysis device 1 calculates an estimated value of diffraction loss for a radio wave communication path based on topographical data for the radio wave communication path between the installation position of a transmitting antenna and the installation position of a receiving antenna. Based on the relationship between the estimated diffraction loss, the diffraction loss calculation formula, and the measured diffraction loss value, the diffraction loss analysis device 1 generates a roundness loss estimation model that estimates roundness loss according to the roundness of a cross section of the shape of the topographical data in the direction of the radio wave communication path in the diffraction loss calculation formula. The cross section in the direction of the radio wave communication path may be a cross section (ground surface) that is tangent to (included in) a (virtual) plane that includes the radio wave communication path (see FIG. 5).

[0015] FIG. 2 is a hardware configuration diagram of the diffraction loss analysis device according to this embodiment. 2, the diffraction loss analysis device 1 is a computer equipped with various hardware components such as a CPU (Central Processing Unit) 101, a ROM (Read Only Memory) 102, a RAM (Random Access Memory) 103, a HDD (Hard Disk Drive) 104, a communication module 105, and a database 106. The radio control device 11 and the radio control device 21 may also have a similar hardware configuration.

[0016] FIG. 3 is a functional block diagram of the diffraction loss analysis device according to this embodiment. The diffraction loss analyzing apparatus 1 executes a processing program, which causes the diffraction loss analyzing apparatus 1 to fulfill the functions of a control unit 111, an acquisition unit 112, an estimated value calculation unit 113, a model generation unit 114, a recording unit 115, and a management unit 116.

[0017] The control unit 111 controls each functional unit of the diffraction loss analysis apparatus 1 . The acquisition unit 112 acquires various data used for processing by the diffraction loss analysis device 1. For example, the acquisition unit 112 acquires, from the radio control device 11 or the radio control device 21, actual measured values of diffraction loss calculated in advance for the radio wave communication path between the installation position of the transmitting antenna and the installation position of the receiving antenna. The acquisition unit 112 acquires topographical data for the radio wave communication path between the installation position of the transmitting antenna and the installation position of the receiving antenna from the database 106. The acquisition unit 112 acquires other data. The estimated value calculation unit 113 calculates an estimated value of the diffraction loss of the radio wave communication path based on topographical data of the radio wave communication path between the installation position of the transmitting antenna and the installation position of the receiving antenna. The model generation unit 114 generates a roundness loss estimation model for estimating a roundness loss according to the roundness of the cross section of the shape of the topographical data in the direction of the radio wave communication path in the diffraction loss calculation formula, based on the relationship between the estimated value of the diffraction loss, the diffraction loss calculation formula, and the actual measured value of the diffraction loss. The recording unit 115 records information indicating the radio wave communication path between the installation position of the transmitting antenna and the installation position of the receiving antenna, information on the topographical data corresponding to the radio wave communication path, and the roundness loss estimation model in association with each other. The management unit 116 presents a roundness loss estimation model to a user terminal or the like based on either the topographical data or the antenna information relating to the installation positions of the new transmitting antenna and receiving antenna.

[0018] FIG. 4 is a diagram showing an outline of processing performed by the diffraction loss analysis device. The diffraction loss analysis device 1 acquires topographical data of a radio wave communication path between the installation position of a transmitting antenna and the installation position of a receiving antenna and a calculation formula for calculating the diffraction loss of the radio wave communication path, and calculates an estimated value of the diffraction loss of the radio wave communication path (step S41). The diffraction loss analysis device 1 acquires an actual measurement value of the diffraction loss of the radio wave communication path between the installation position of the transmitting antenna and the installation position of the receiving antenna (step S42). The diffraction loss analysis device 1 generates a roundness loss estimation model using a machine learning technique, which estimates the roundness loss according to the roundness of the cross section of the shape of the topographical data in the direction of the radio wave communication path in the diffraction loss calculation formula, based on the relationship between the estimated diffraction loss value, the diffraction loss calculation formula, and the actual measurement value of the diffraction loss (step S43). The diffraction loss analysis device 1 associates a combination ID that identifies the combination of the transmitting antenna and the receiving antenna, topographical data of the radio wave communication path between the installation position of the transmitting antenna and the installation position of the receiving antenna, and the roundness loss estimation model, and records them (step S44). The diffraction loss analysis device 1 presents a roundness loss estimation model based on either the topographical data or the antenna information (combination ID) relating to the installation positions of the new transmitting antenna and receiving antenna (step S45).

[0019] FIG. 5 is a diagram illustrating parameters used in the calculation formula for the roundness loss. The formula for calculating roundness loss is used to calculate the loss that occurs when radio waves traveling along radio wave communication paths d1 and d2 for OH communication that are in contact with the roundness of a cross-section of the earth's surface, as shown in Figure 5, are diffracted at the earth's surface, and can be expressed as T(m, n). m and n can be expressed by formulas (1) and (2). In formula (1), d1 and d2 are the radio wave communication paths of the radio waves from each opposing antenna and are expressed as values that indicate distance. R is the radius of a circle that models the roundness of the earth's surface, such as a mountain peak, and h is the height of the earth's surface that represents the roundness. In Figure 5, α1 and α2 represent the angle between the directional directions of the transmitting antenna and the receiving antenna. Note that the more rounded the place, such as the top of a mountain, the more difficult it is to diffract.

[0020]

number

[0021]

number

[0022] The diffraction loss A of the radio wave communication path can be expressed as in equation (3) using the knife-edge diffraction loss J(v) at the vertex where the radio waves d1 and d2 intersect and the roundness diffraction loss T(m, n).

[0023]

number

[0024] Note that T(m, n) can also be calculated using the following formulas (4) and (5) in accordance with the regulations of the ITU-R (International Telecommunication Union Radiocommunication Sector).

[0025]

number

[0026]

number

[0027] FIG. 6 is a diagram showing a processing flow of the diffraction loss analysis device. The processing flow of the diffraction loss analyzing apparatus 1 according to this embodiment will be described below. The acquisition unit 112 of the diffraction loss analysis apparatus 1 receives designation of a transmitting antenna and a receiving antenna based on an operation by an administrator or the like (step S101). The acquisition unit 112 acquires, from the database 106 or the like, topographical data of the earth's surface corresponding to the radio wave communication path when the antenna 10 or the antenna 20 is the transmitting antenna or the receiving antenna (step S102). The topographical data may be information indicated by the radio wave communication path d1, the radio wave communication path d2, the radius R, the height h, or the like, which are identified by modeling the acquired topographical data. The topographical data may also be the coordinates (latitude, longitude, altitude) of the transmitting antenna and the receiving antenna, the distance, the coordinates (latitude, longitude, altitude) of the peaks of mountainous regions between the antennas, the coordinates (latitude, longitude, altitude) of points at a predetermined interval on the straight line between the antennas, or the like.

[0028] The acquisition unit 112 also acquires a calculation formula for diffraction loss (step S103). The acquisition unit 112 outputs the acquired information to the estimate calculation unit 113. The estimate calculation unit 113 uses the parameters, such as the radio wave communication path d1, the radio wave communication path d2, the radius R, and the height h, that are identified by modeling the acquired topographical data as shown in FIG. 5, to calculate estimates of the knife-edge diffraction loss J(v), the roundness loss T(m,n), and the diffraction loss A using the above-mentioned formula or known formulas (step S104). The estimate calculation unit 113 outputs the estimated values of the diffraction loss A, the knife-edge diffraction loss J(v), and the roundness loss T(m,n) to the model generation unit 114.

[0029] The acquiring unit 112 acquires a previously calculated actual value of diffraction loss A on the radio wave communication path between the specified transmitting antenna and receiving antenna (step S105). This actual value of diffraction loss A may be a value calculated by the radio control device 11 or the radio control device 21, or may be a value calculated by the diffraction loss analysis device 1 using a known technique based on a received power value or a transmitted power value acquired from the radio control device 11 or the radio control device 21. The actual measured value A of diffraction loss is recorded in the database 106 for each combination of a transmitting antenna and a receiving antenna, and the acquiring unit 112 may acquire the actual measured value A of diffraction loss recorded in association with a combination ID indicating the specified combination of a transmitting antenna and a receiving antenna from the database 106. The acquiring unit 112 outputs the actual measured value of diffraction loss A to the model generating unit 114.

[0030] The model generation unit 114 acquires the relationship between the measured value of diffraction loss A, the estimated values of diffraction loss A, knife-edge diffraction loss J(v), and roundness loss T(m,n), and the topographical data. By repeating the above process, the model generation unit 114 acquires multiple relationships between the measured value of diffraction loss A, the estimated values of diffraction loss A, knife-edge diffraction loss J(v), and roundness loss T(m,n), and the topographical data, calculated based on multiple timings and multiple pieces of topographical data. The model generation unit 114 performs machine learning on multiple pieces of data indicating the relationship between the measured value of diffraction loss A, the estimated values of diffraction loss A, knife-edge diffraction loss J(v), and roundness loss T(m,n), and the topographical data, and generates a calculation model for roundness loss T(m,n) such that the estimated value of diffraction loss A, which is the sum of the estimated value of roundness loss T(m,n) and knife-edge diffraction loss J(v), approaches the measured value of diffraction loss A (step S106). Any known machine learning technique may be used to generate a calculation model for the roundness loss T(m,n).

[0031] The model generation unit 114 outputs a combination ID indicating the specified combination of the transmitting antenna and the receiving antenna, topographical data corresponding to the radio wave communication path of the transmitting antenna and the receiving antenna, and the calculated calculation model of the rounding loss T(m, n) to the recording unit 115. The recording unit 115 associates the combination ID indicating the specified combination of the transmitting antenna and the receiving antenna, the topographical data corresponding to the radio wave communication path of the transmitting antenna and the receiving antenna, and the calculated calculation model of the rounding loss T(m, n) and records them in the database 106 (step S107).

[0032] The diffraction loss analysis device 1 may perform the same process as described above for each different combination of transmitting antenna and receiving antenna, and for each combination, associate a combination ID, topographical data, and a calculation model for the roundness loss T(m, n) with each other, and record them in the database 106. This makes it possible to record a calculation model for the roundness loss T(m, n) that can accurately calculate the roundness loss T(m, n) according to the combination of transmitting antenna and receiving antenna and the topographical data.

[0033] When the management unit 116 of the diffraction loss analysis device 1 acquires a combination ID indicating a transmitting antenna and a receiving antenna from a user such as an administrator via the interface, the management unit 116 reads out a calculation model for the roundness loss T(m,n) that is associated with the combination ID and recorded in the database 106, and presents the model to a terminal used by the administrator (step S108). Alternatively, when the management unit 116 of the diffraction loss analysis device 1 acquires topography data from a user such as an administrator via the interface, the management unit 116 may read out a calculation model for the roundness loss T(m,n) that is associated with topography data similar to the topography data and present the model to a terminal used by the administrator. The recording unit 115 of the diffraction loss analysis device 1 may record the calculation model for the roundness loss T(m,n) in the database 106, associated with the installation positions, such as the latitude, longitude, and altitude, of the transmitting antenna and the receiving antenna. Then, the management unit 116 may acquire the installation positions of the new transmitting antenna and the new receiving antenna from a user such as an administrator via an interface, read out a calculation model of the rounding loss T(m, n) that is associated with each installation position close to the acquired installation positions and recorded in the database 106, and present the model to a terminal used by the administrator.

[0034] This allows the administrator to obtain a calculation model that can calculate the appropriate rounding loss T(m,n) for the transmitting antenna and receiving antenna during processing such as line design, and calculate the rounding loss T(m,n).

[0035] While the knife-edge diffraction loss J(v) can be easily calculated, the value of the roundness loss T(m,n) is difficult to estimate because it is based on topographical data. For this reason, related technologies fix the value of the roundness loss T(m,n) to a predetermined value and calculate the diffraction loss A corresponding to the radio wave communication path. However, by performing the processing described above, the roundness loss T(m,n) can be easily calculated based on a roundness loss estimation model that estimates the roundness loss according to the roundness of the cross section of the topographical data shape of the radio wave communication path between the transmitting antenna and the receiving antenna in the direction of the radio wave communication path. This enables highly accurate analysis of the diffraction loss, which is one type of propagation loss in the radio wave communication path between the installation position of an arbitrary transmitting antenna and the installation position of a receiving antenna.

[0036] FIG. 7 is a diagram showing an example of the configuration of a diffraction loss analysis device according to this embodiment. FIG. 8 is a diagram showing a processing flow by the diffraction loss analysis device shown in FIG. The diffraction loss analysis device 1 performs at least the functions of an estimated value calculation unit 113 and a model generation unit 114 . The estimated value calculation unit 113 calculates an estimated value of the diffraction loss of the radio wave communication path based on topographical data of the radio wave communication path between the installation position of the transmitting antenna and the installation position of the receiving antenna (step S201). The model generation unit 114 generates a roundness loss estimation model that estimates the roundness loss according to the roundness of the cross section of the shape of the topographical data in the direction of the radio wave communication path in the diffraction loss calculation formula, based on the relationship between the estimated value of the diffraction loss, the diffraction loss calculation formula, and the actual measured value of the diffraction loss (step S202).

[0037] Each of the above-mentioned devices has a computer system built in. The steps of each of the above-mentioned processes are stored in the form of a program on a computer-readable recording medium, and the computer reads and executes this program to perform the above-mentioned processes. Here, computer-readable recording medium refers to a magnetic disk, magneto-optical disk, CD-ROM, DVD-ROM, semiconductor memory, etc. Alternatively, the computer program may be distributed to a computer via a communication line, and the computer that receives the program may execute the program.

[0038] The program may also be a program for realizing some of the functions described above, or may be a so-called differential file (differential program) that can realize the functions described above in combination with a program already recorded in the computer system.

[0039] This application claims priority based on Japanese Patent Application No. 2021-151197, filed on September 16, 2021, the disclosure of which is incorporated herein in its entirety. [Industrial Applicability]

[0040] The present disclosure may be applied to a diffraction loss analysis device, a diffraction loss analysis method, and a recording medium. [Explanation of symbols]

[0041] 1. Diffraction loss analysis device 10,20...antenna 100 Radio communication system 111 Control unit 112...Acquisition part 113 Estimated value calculation section 114...Model generation unit 115 Recording section 116...Management Department

Claims

1. an estimate calculation means for calculating, based on topographical data indicating the ground surface corresponding to the radio wave communication path between the installation position of the transmitting antenna and the installation position of the receiving antenna, an estimate of diffraction loss of the radio wave communication path, the estimate of roundness loss corresponding to the roundness of a cross section of the ground surface indicated by the topographical data in the direction of the radio wave communication path, and an estimate of knife-edge diffraction loss at an apex of the radio wave communication path connecting the transmitting antenna and the receiving antenna, using the diffraction loss calculation formula; a model generation means for performing machine learning on the relationship between the estimated value of the roundness loss, the estimated value of the knife-edge diffraction loss, the sum of the estimated value of the roundness loss and the estimated value of the knife-edge diffraction loss, and the actually measured value of the diffraction loss of the radio wave communication path, and generating a roundness loss estimation model for estimating the roundness loss according to the roundness of a cross section of the earth's surface indicated by the topographical data in the direction of the radio wave communication path; A diffraction loss analysis device comprising:

2. the diffraction loss calculation formula includes a knife-edge diffraction loss calculation formula and a roundness loss calculation formula, and the estimated total value is the sum of the knife-edge diffraction loss calculated by the knife-edge diffraction loss calculation formula and the roundness loss calculated by the roundness loss calculation formula; The diffraction loss analysis device according to claim 1 .

3. The model generation means generates the roundness loss estimation model by performing the machine learning so that the sum of the estimated value of the roundness loss and the estimated value of the knife-edge diffraction loss approaches an actual measured value of the diffraction loss of the radio wave communication path.

3. The diffraction loss analysis device according to claim 1 or 2.

4. The model generation means generating the roundness loss estimation model for each relationship between the installation position of the transmitting antenna and the installation position of the receiving antenna; 3. The diffraction loss analysis device according to claim 1 or 2.

5. a recording means for recording topographical data of a radio wave communication path between the installation position of the transmitting antenna and the installation position of the receiving antenna, and the roundness loss estimation model for each relationship between the installation position of the transmitting antenna and the installation position of the receiving antenna; a presentation means for presenting a roundness loss estimation model identified from the roundness loss estimation models recorded for each relationship between the installation positions of the transmitting antenna and the receiving antenna, based on either topographical data or antenna information relating to new installation positions of the transmitting antenna and the receiving antenna; The diffraction loss analysis device according to claim 1 or 2, comprising:

6. calculating, using the diffraction loss calculation formula, an estimated value of diffraction loss of a radio wave communication path based on topographical data indicating the earth's surface corresponding to the radio wave communication path between the installation position of a transmitting antenna and the installation position of a receiving antenna, the estimated value being a roundness loss corresponding to the roundness of a cross section of the earth's surface indicated by the topographical data in the direction of the radio wave communication path, and an estimated value of knife-edge diffraction loss at an apex of the radio wave communication path connecting the transmitting antenna and the receiving antenna; machine learning the relationship between the estimated value of the roundness loss, the estimated value of the knife-edge diffraction loss, the sum of the estimated value of the roundness loss and the estimated value of the knife-edge diffraction loss, and the actual measured value of the diffraction loss of the radio wave communication path, to generate a roundness loss estimation model that estimates the roundness loss according to the roundness of a cross section of the earth's surface indicated by the topographical data in the direction of the radio wave communication path; Diffraction loss analysis method.

7. The diffraction loss analyzer computer calculating, based on topographical data indicating the earth's surface corresponding to the radio wave communication path between the installation position of the transmitting antenna and the installation position of the receiving antenna, an estimated value of diffraction loss of the radio wave communication path, the estimated value of roundness loss corresponding to the roundness of a cross section of the earth's surface indicated by the topographical data in the direction of the radio wave communication path, and an estimated value of knife-edge diffraction loss at an apex of the radio wave communication path connecting the transmitting antenna and the receiving antenna, using the diffraction loss calculation formula; generating a roundness loss estimation model that estimates a roundness loss according to the roundness of a cross section of the earth's surface indicated by the topographical data in the direction of the radio wave communication path by machine learning a relationship between the estimated value of the roundness loss, the estimated value of the knife-edge diffraction loss, a sum of the estimated value of the roundness loss and the estimated value of the knife-edge diffraction loss, and an actual measured value of the diffraction loss of the radio wave communication path; A program that executes the following.

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