Terrain correction method determination device, terrain correction method determination method, and program

Abstract

A terrain correction method determination device according to the present disclosure determines a terrain correction method as being one of a land-sea mixed passage correction, a mountain correction, a hilly terrain correction, a sloped terrain correction, or a non-correction on the basis of information about points between a reference point and an evaluation target point. When the ratio of the number of points determined to be on the water surface to the number of all of the points between the reference point and the evaluation target point is equal to or greater than a certain ratio, the terrain correction method is determined to be the land-sea mixed passage correction. When the altitude difference between the reference point and a maximum altitude point at which the altitude is greatest among all of the points is equal to or greater than a predetermined value, and the planar distance between the maximum altitude point and the peak of every mountain is equal to or less than a predetermined value, the terrain correction method is determined to be the mountain correction.

Description

Terrain correction method determination device, terrain correction method determination method and program

[0001] The present invention relates to a terrain correction method determination device, a terrain correction method determination method, and a program.

[0002] In wireless communications, when creating a received power level map or the like, an equation is used to estimate radio wave propagation characteristics, including terrain correction. Non-Patent Document 1 explains propagation characteristics in irregular terrain such as hilly terrain. Non-Patent Document 2 explains the Okumura-Hata equation, which is a propagation characteristic estimation equation.

[0003] Patent No. 5845198

[0004] Edited by Yoshihisa Okumura and Masaaki Shinji: "Fundamentals of Mobile Communications", edited by the Institute of Electronics, Information and Communication Engineers (1986 / 10 / 01), published by Coronasha, A5 size, pp. 47-53, ISBN: 978-4-88552-065-5, https: / / www.coronasha.co.jp / np / isbn / 9784885520655 / 2.6 Land Mobile Propagation 2.6.3 Propagation Characteristics in Irregular Terrain Antenna and Propagation Research Committee (A.P.) Okumura-Hata Formula https: / / www.ieice.org / cs / ap / misc / denpan-db / prop_model_db / model_list / okumura-hata-formula /

[0005] However, although Non-Patent Document 1 describes multiple terrain correction methods depending on the type of irregular terrain, it does not clearly explain in what cases they should be applied. Also, although Patent Document 1 discloses a propagation characteristic estimation method, it is not clear what processing is used to select the terrain correction to be applied. An object of the present invention is to determine an appropriate terrain correction method.

[0006] One aspect of the present invention is a terrain correction method determination device that determines a terrain correction method to be one of land-sea mixed passage correction, mountain correction, hilly terrain correction, slope terrain correction, and no correction based on information on points between a reference point and an evaluation point, and determines the terrain correction method to be the land-sea mixed passage correction when the ratio of the number of points determined to be water surfaces to the number of all points between the reference point and the evaluation point is equal to or greater than a certain level, and determines the terrain correction method to be the mountain correction when the difference in elevation between the reference point and the maximum elevation point that has the highest elevation among all points is equal to or greater than a certain level and the planar distances between the maximum elevation point and the summit of a mountain are all equal to or less than a certain level. and when the number of points that are undulation peaks among all the points is equal to or greater than a predetermined number, determines the terrain correction method to be the hilly terrain correction; when the maximum value of the ratio of the difference between an angle between the reference point and an inflection point among all the points and the first angle, which is the angle between the reference point and the evaluation point, to the first angle, is equal to or greater than a predetermined value, determines the terrain correction method to be the slope terrain correction; and when the terrain correction method is not determined to be any of the land-sea mixed passage correction, the mountain correction, the hilly terrain correction, and the slope terrain correction, determines the terrain correction method to be no correction.

[0007] The terrain correction method determination device, the terrain correction method determination method, and the program of the present invention can determine an appropriate terrain correction method.

[0008] FIG. 1 is a diagram showing a terrain correction method determination device according to the present embodiment. FIG. 2 is a terrain profile created based on the planar distance from a reference point and the altitude included in the terrain information. FIG. 3 is an example showing terrain information for each point. FIG. 4 is a diagram showing points determined to be inflection points or water surfaces extracted by the terrain information analysis unit. FIG. 5 is a flowchart showing a method for extracting points that are undulation peaks or valley points. FIG. 6 is a flowchart showing an example of a method for extracting points that are undulation peaks or valley points. FIG. 7 is a flowchart showing the operation of the terrain correction method determination device. FIG. 8 is a flowchart showing a method for determining a correction method. FIG. 9 is a flowchart showing a method for calculating a correction value K in land-sea mixed passage correction. FIG. 10 is a flowchart showing the ratio (C) of points determined to be water surfaces to all points. ｄｓ / C ｄａ ), the planar distance d between the reference point and the evaluation point, and the correction value K for the land-sea mixed passage correction ｓThis is a graph showing the relationship between H and d when H=200m. １ , d ２ , K. ｉｍ ΣH and K ｍｍ 10 is a graph showing the relationship between the terrain undulation height Δh and the hill correction value K ｈ 10 is a graph showing the relationship between the terrain undulation height Δh and the hill fine correction value K ｈｆ 10 is a graph showing the relationship between the planar distance d between the reference point and the evaluation point and the inclination angle θ between the reference point and the evaluation point. ｍ and the slope correction value K ｓｐ 10 is a graph showing the relationship between the correction value calculated by each terrain correction method and the correction value calculated by each terrain correction method.

[0009] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram showing a terrain correction method determination device 1 according to this embodiment. The terrain correction method determination device 1 includes a terrain information acquisition unit 11, a terrain information analysis unit 12, a terrain correction method determination unit 13, and an output unit 14. The terrain information acquisition unit 11 acquires terrain information. The terrain information is information about each point between a predetermined reference point and an evaluation point to be evaluated. The reference point is the location of a base station.

[0010] The topographical information includes information on the planar distance from a reference point to each point. The planar distance is the distance between two points when altitude is ignored, and is the straight-line distance between two points on a flat map. The planar distance is a value calculated, for example, based on the latitude and longitude of the two points.

[0011] The topographical information includes elevation information for each point. The topographical information includes location information for each point (e.g., longitude and latitude for each point). The topographical information includes land use type information for each point. The land use type information is, for example, land use subdivision mesh data provided by the Ministry of Land, Infrastructure, Transport and Tourism, and indicates, for example, whether the land use type is river land, lakes, marshes, or seawater.

[0012] Figure 2 shows a terrain profile created based on the planar distance and altitude from a reference point included in the terrain information. The terrain profile shown in Figure 2 is a terrain profile between the reference point and an evaluation point located 10,000 m from the reference point.

[0013] 3 shows an example of topographical information for each point, which is associated with the distance from the reference point, altitude, location information, and land use type information for each point.

[0014] The topographical information analysis unit 12 analyzes the topographical information and determines that, among all points between the reference point and the evaluation point, points whose land use type is related to water (rivers, lakes, marshes, and sea areas) are water surfaces.

[0015] The topographic information analysis unit 12 extracts points that are, for example, undulation peaks or valleys. FIG. 5 is a flowchart showing a method for extracting points that are undulation peaks or valleys. The topographic information analysis unit 12 calculates the difference in elevation and the slope between adjacent points (step S121). The topographic information analysis unit 12 extracts points where the slope changes from positive to negative as inflection points (step S122). The topographic information analysis unit 12 extracts points where the slope changes from positive to negative as undulation peaks, and points where the slope changes from negative to positive as valleys (step S123). Points where the slope changes from positive to zero or from zero to positive include points where the slope changes from negative to zero or from zero to positive.

[0016] Note that if the slope changes from positive to 0 and then changes from 0 to positive, the topographic information analysis unit 12 does not need to extract those two points as inflection points. Also, if the slope changes from negative to 0 and then changes from 0 to negative, the topographic information analysis unit 12 does not need to extract those two points as inflection points.

[0017] When two adjacent points are both extracted as inflection points, and the absolute value of the slope between those two points is equal to or less than a predetermined value, the topographic information analysis unit 12 may exclude those two inflection points from the inflection points to be extracted. This is because when the absolute value of the slope between two points is equal to or less than a predetermined value, the two inflection points can be considered to be points located midway along an upslope or downslope. When the difference in height between an adjacent undulation vertex is equal to or less than a predetermined value, the topographic information analysis unit 12 may exclude that undulation vertex from the undulation vertices to be extracted. When the difference in height between an adjacent valley point is equal to or less than a predetermined value, the topographic information analysis unit 12 may exclude that valley point from the valley points to be extracted. When the difference in height between an adjacent undulation vertex and valley point is equal to or less than a predetermined value, the undulation vertex and valley point may be excluded from the undulation vertices and valley points to be extracted.

[0018] FIG. 6 is a flowchart showing an example of a method for extracting points that are undulation peaks or valleys. The topographic information analysis unit 12 calculates the difference in elevation and the slope between adjacent points (step S121a). The topographic information analysis unit 12 extracts points where the slope changes from positive to negative as inflection points (step S122a). The topographic information analysis unit 12 excludes adjacent inflection points whose elevation difference is equal to or less than a predetermined value (step S123a). The topographic information analysis unit 12 excludes, from the remaining inflection points, inflection points where the slopes of adjacent inflection points are the same (step S124a). The topographic information analysis unit 12 calculates the slopes of adjacent inflection points among the remaining inflection points, and extracts points where the slope changes from positive to negative as inflection points (step S125). The topographical information analysis unit 12 extracts points where the slope changes from positive to negative as undulation peaks, and extracts points where the slope changes from negative to positive as valleys.

[0019] 6, it is not necessary to repeat the same processing step, that is, the extraction operation, many times, and therefore it is possible to extract inflection points with fewer processing times.

[0020] The topographical information analysis unit 12 calculates the slope angle between the reference point and the evaluation target point, and the slope angle between the reference point and the inflection point.

[0021] FIG. 4 is a diagram showing inflection points extracted by the topographical information analysis unit 12 and points determined to be water surfaces.

[0022] The terrain correction method determination unit 13 determines a terrain correction method based on the analysis results by the terrain information analysis unit 12. The method for determining the terrain correction method will be described later.

[0023] The output unit 14 outputs the determined terrain correction method to the correction value calculation device 2 .

[0024] 7 is a flowchart showing the operation of the terrain correction method determination device 1. The terrain information acquisition unit 11 acquires terrain information (step S11). The terrain information analysis unit 12 analyzes the terrain information (step S12). The terrain correction method determination unit 13 determines a terrain correction method (step S13). The output unit 14 outputs the terrain correction method to the correction value calculation device 2 (step S14). Note that the operations do not necessarily have to be performed in this order, and the terrain correction method determination device 1 may analyze terrain information as necessary when determining a terrain correction method.

[0025] The correction value calculation device 2 calculates a correction value K based on the terrain correction method determined by the terrain correction method determination device 1. The correction value calculation device 2 outputs the calculated correction value K. The calculation method of the correction value K, which differs depending on the terrain correction method, will be described later. The correction value K is a value added to the propagation loss L in the Okumura-Hata formula described in Non-Patent Document 2. In the Okumura-Hata formula, the received power P Ｒ is calculated using formula (1).

[0026] In formula (1), P Ｔ is the transmission power, G Ｔ is the transmit antenna gain, L Ｆ is the power supply loss, G Ｒ is the receiving antenna gain, and L is the propagation loss. L is usually calculated by equation (2).

[0027] In equation (2), f is the frequency, h ｂ is the antenna height at the reference point, d is the distance between the transmitter and receiver, h ｍ is the antenna height at the evaluation point, α(h ｍ) is the height characteristic of the evaluation point. ｍ ) is calculated by equation (3) when the location is a small or medium-sized city, by equation (4) when the location is a large city and the frequency f is 200 MHz or less, and by equation (5) when the location is a large city and the frequency f is 400 MHz or more.

[0028] In addition, when the location is a suburban area or an open area, the correction shown in Equation (6) and Equation (7) is performed, and the propagation loss in the suburban area L ｐｓ , propagation loss in open areas L ｐｏ Calculate.

[0029] The correction value calculation device 2 may be realized as the same device as the terrain correction method determination device 1. Furthermore, the correction value calculation device 2 may refer to the terrain information or the analysis results of the terrain information as necessary when calculating the correction value.

[0030] The method by which the terrain correction method determination unit 13 determines the terrain correction method will be described below. When the ratio of points that are water surfaces to all points between the reference point and the evaluation point is equal to or greater than a certain level, the terrain correction method determination unit 13 determines the terrain correction method to be land-sea mixed passage correction. Hereinafter, the ratio of points that are water surfaces to all points between the reference point and the evaluation point is equal to or greater than a certain level, which is referred to as condition C1. For example, condition C1 means that the ratio of points that are water surfaces to all points between the reference point and the evaluation point is equal to or greater than 40%. The ratio of points that are water surfaces to all points between the reference point and the evaluation point being equal to or greater than a certain level is expressed as follows: ｄｓ The number of all points in C ｄａ Ratio to (C ｄｓ / C ｄａ ) is above a certain level.

[0031] The terrain correction method determination unit 13 determines the terrain correction method to be mountain correction when condition C1 is not satisfied, the elevation difference between the reference point and the maximum elevation point is equal to or greater than a predetermined value, and the planar distance between the maximum elevation point and the peak of the mountain is equal to or less than a certain value. The maximum elevation point is the point with the highest elevation of all points between the reference point and the evaluation target point. Hereinafter, condition C2 refers to the elevation difference between the reference point and the maximum elevation point being equal to or greater than a predetermined value, and the planar distance between the maximum elevation point and the peak of the mountain being equal to or less than a certain value. Condition C2, for example, refers to the elevation difference between the reference point and the maximum elevation point being equal to or greater than 110 m, and the planar distance between the maximum elevation point and the peak of the mountain being equal to or less than a certain value.

[0032] The terrain correction method determination unit 13 calculates the planar distance between the maximum elevation point and the mountain peak from the information on the maximum elevation point and the latitude and longitude, and the list information on the latitude and longitude of the mountain peak, and determines the shortest planar distance l ｍｔ is equal to or less than a certain value, it is determined that the planar distance between the maximum elevation point and the summit of the mountain is equal to or less than a certain value.

[0033] When conditions C1 and C2 are not satisfied and the number of vertices of the terrain is equal to or greater than a predetermined number, the terrain correction method determination unit 13 determines the terrain correction method to be hilly terrain correction. Hereinafter, the fact that the number of vertices of the terrain is equal to or greater than a predetermined number will be referred to as condition C3.

[0034] If the conditions C1, C2, and C3 are not satisfied, the terrain correction method determination unit 13 determines that the angle θ ｍ The angle θ between the reference point and the inflection point ｊ and θ ｍ When the maximum value of the difference ratio is equal to or greater than a predetermined value, the terrain correction method is determined to be slope terrain correction. ｍ Angle θ ｊ and θ ｍ The condition C4 is that the maximum value of the ratio of the difference between the values ​​is equal to or greater than a predetermined value. The condition C4 is expressed by the following equation (8).

[0035] R ＴＨ is a predetermined value, for example, 10%.

[0036] If the conditions C1, C2, C3, and C4 are not satisfied, the terrain correction method determination unit 13 determines the terrain correction method to be no correction. If the terrain correction method is no correction, the correction value calculation device 2 calculates the correction value K=0.

[0037] 8 is a flowchart showing the correction method determination method. If condition C1 is satisfied (step S131: YES), the terrain correction method determination unit 13 determines the correction method to be land-sea mixed passage correction (step S132). If condition C1 is not satisfied (step S131: NO) but condition C2 is satisfied (step S133: YES), the terrain correction method determination unit 13 determines the correction method to be mountain correction (step S134). If condition C2 is not satisfied (step S133: NO) but condition C3 is satisfied (step S135: YES), the terrain correction method determination unit 13 determines the correction method to be hilly terrain correction (step S136). If condition C3 is not satisfied (step S135: NO) but condition C4 is satisfied (step S137: YES), the terrain correction method determination unit 13 determines the correction method to be slope terrain correction (step S138). If the condition C4 is not satisfied (step S137: NO), the correction method is determined to be no correction (step S139).

[0038] The terrain correction method determination unit 13 may determine that the terrain correction method is no correction when conditions C1 and C2 are not satisfied and the planar distance between the reference point and the evaluation point is equal to or less than a predetermined value. More specifically, the terrain correction method determination unit 13 may determine that the terrain correction method is no correction when conditions C1 and C2 are not satisfied and the planar distance between the reference point and the evaluation point is equal to or less than 5 km. Hilly terrain correction is performed assuming that the planar distance between the reference point and the evaluation point is relatively short (10 km or less), but if the planar distance is even shorter, such as less than 5 km, it falls outside the range in which hilly terrain correction can be applied (the distance d between the reference point and the evaluation point in the graph showing the hilly terrain correction value in Figure 13 is 0.05). ＭＲIn addition, the correction value calculated when the terrain is slope terrain correction takes a small value when the planar distance between the reference point and the evaluation point is short (in the graph showing slope terrain correction in Figure 15, when the distance d between the reference point and the evaluation point is < 5 km, the value is on a curve with a smaller slope than the dashed curve where d < 10 km, and the slope terrain correction value K ｓｐ (The difference is only about 1 to 2 dB.) Therefore, when the planar distance between the reference point and the evaluation point is equal to or less than a predetermined value, the amount of calculation can be reduced by determining that no correction is to be performed as the terrain correction method.

[0039] If the conditions C1, C2, and C3 are not satisfied, the terrain correction method determination unit 13 determines that the slope angle θ ｍ If the value of the inclination angle θ is within a predetermined range, the terrain correction method may be determined to be no correction. In addition, in determining whether condition C3 is satisfied, the reference point may be changed to limit the terrain information to be investigated to a range with a shorter planar distance from the evaluation target point. The predetermined range of values ​​is a range in which the terrain is determined to be not inclined. ｍ If the value is within a predetermined range, a valid correction value cannot be calculated using slope terrain correction. Therefore, the amount of calculation can be reduced by determining that no correction is to be performed as the terrain correction method.

[0040] The following describes how to calculate the correction value K, which differs depending on the terrain correction method. Note that correction values ​​calculated using different methods may be distinguished by adding a suffix to the correction value K. For example, if the correction value for land-sea mixed passage correction is K, ｓ 9 is a flowchart showing a method for calculating the correction value K in the land-sea mixed passage correction. When the terrain correction method is the land-sea mixed passage correction, the correction value calculation device 2 calculates a correction coefficient P based on the position of the water surface and the total planar distance (step S141). The correction value calculation device 2 calculates the number C of points determined to be water surfaces based on the number C of points determined to be water surfaces. ｄｓ The number of all points in C ｄａ If the number of points C determined to be the water surface is less than half of the number of points C determined to be the water surface and the position of the water surface is closer to the reference point, the correction coefficient P is calculated as 0. ｄｓ The number of all points in C ｄａIf the number of points C determined to be the water surface is less than half of the number of points C determined to be the water surface and the position of the water surface is closer to the evaluation target point, the correction coefficient P is calculated as 1. ｄｓ The number of all points in C ｄａ If the number of the errors is equal to or greater than half, the correction coefficient P is calculated by the formula (9).

[0041] In formula (9), L ｃ is the distance from the reference point to the point determined to be the water surface where the cumulative distribution is at the 50th percentile. ｃ is the distance from the reference point to the midpoint among the points determined to be the water surface. ｓｔ is the distance between the points. ｓｔ ×C ｄｓ is the distance to the water surface. d is the planar distance between the reference point and the evaluation point.

[0042] The correction value calculation device 2 is L ｃ -L ｓｔ ×C ｄｓ If / 2 is 0 or less, the correction coefficient P is calculated as 0, and L ｃ -L ｓｔ ×C ｄｓ / 2 is greater than 0, and L ｃ +L ｓｔ ×C ｄｓ If / 2 is equal to or greater than d, the correction coefficient P is calculated as 1, and L ｃ -L ｓｔ ×C ｄｓ / 2 is greater than 0, and L ｃ +L ｓｔ ×C ｄｓ When / 2 is smaller than d, the correction coefficient P can be calculated by the formula (9) in the same manner as the above method.

[0043] Thereafter, the correction value calculation device 2 calculates a correction value K based on the planar distance between the reference point and the evaluation point, the ratio of the points determined to be the water surface to all points, and the correction coefficient P (step S142). ｄｓ / C ｄａ ), the planar distance d between the reference point and the evaluation point, and the correction value K for the land-sea mixed passage correction ｓ1 is a graph showing the relationship between the correction value calculation device 2 and C ｄｓ / C ｄａ , d, K ｓ The relationship between ｄｓ / C ｄａ , d, the correction value K in the land-sea mixed passage correction ｓ Calculate.

[0044] The correction value calculation device 2 calculates the correction value K using a graph (graph indicated by b) showing the correction value when the water surface is on the reference point side, a graph (graph indicated by a) showing the correction value when the water surface is on the evaluation target point side, and a graph (hereinafter referred to as the intermediate value graph) showing the intermediate value between the graphs indicated by a and b. ｓ When the correction coefficient P is 0.5 or less, the correction value calculation device 2 calculates the correction value K using the graph indicated by b and the intermediate value graph. ｓ Specifically, the correction value calculation device 2 calculates a given C ｄｓ / C ｄａ , d, the correction value K ｂ and the correction value K shown in the intermediate value graph ｍｉｄ Based on this, the correction value K ｓ Calculate.

[0045] When the correction coefficient P is greater than 0.5, the correction value calculation device 2 calculates the correction value K using the graph indicated by a and the intermediate value graph. ｓ Specifically, the correction value calculation device 2 calculates a given C ｄｓ / C ｄａ , d, the correction value K ａ and the correction value K shown in the intermediate value graph ｍｉｄ Based on this, the correction value K is calculated using equation (11). ｓ Calculate.

[0046] Using the graph, the correction value K ｓ The correction value calculation device 2 calculates the correction value K using the calculation formula shown in the graph. ｓ Although only two graphs that change depending on the change in d are shown in FIG. 10, the correction value calculation device 2 calculates the difference between d and C in the calculation formula shown in the graph. ｄｓ / C ｄａUsing the approximate formula for the correction value K ｓ Hereinafter, the calculation method of the correction value for mountain correction, hilly land correction, and slope terrain correction will be described using graphs. The correction value calculation device 2 calculates the value of d in the calculation formula shown in the graph and d ２ , ΣH, Δh, θ ｍ The correction value K may be calculated using an approximation formula for each combination of the above.

[0047] When the terrain correction method is mountain correction, the correction value calculation device 2 determines whether the terrain correction method is isolated mountain correction or multiple mountain correction. Isolated mountain correction is correction when there is only one mountain, and multiple mountain correction is correction when there are two or more mountains. The correction value calculation device 2 calculates all slope angles between the reference point and the ridge peaks and evaluation target points. Then, it extracts the point with the largest slope angle from among the ridge peaks and evaluation target points, and calculates all slope angles between the ridge peaks and evaluation target points using the extracted point as a new reference point. This process is repeated until the extracted point becomes the evaluation target point. If there is one extracted point other than the evaluation target point, the terrain correction method is isolated mountain correction. If there are two or more extracted points other than the evaluation target point, the terrain correction method is multiple mountain correction.

[0048] In the case of isolated mountain correction, the correction value calculation device 2 calculates the distance d between the reference point and the extracted point. １ , the distance d between the extracted point and the evaluation point ２ , and the elevation H of the extracted points excluding the evaluation target points, the isolated mountain correction value K ｉｍ Figure 11 shows the d when H = 200 m. １ , d ２ , K. ｉｍ For example, the correction value calculation device 2 calculates the value of d when H=200 m. １ , d ２ , K. ｉｍ A graph showing the relationship between １ , d ２ From the value of K ｉｍ Calculate K ｉｍ By multiplying this by a correction coefficient α = 0.07√H based on the altitude H, the isolated mountain correction value K at the desired altitude is obtained. ｉｍ can be calculated.

[0049] In the case of multiple mountain correction, the correction value calculation device 2 calculates a multiple mountain correction value K based on the sum ΣH of the elevations of the extracted points excluding the evaluation target point. ｍｍ Calculate the following equation. ｍｍ 1 is a graph showing the relationship between ΣH and K. ｍｍ Based on the graph showing the relationship between ｍｍ Calculate.

[0050] When the terrain correction method is hilly terrain correction, the correction value calculation device 2 calculates a high representative value and a low representative value from the height data of each point. The high representative value and the low representative value are quantiles, and for example, the high representative value is the 90th percentile of the height of each point, and the low representative value is the 10th percentile of the height of each point.

[0051] The correction value calculation device 2 calculates the terrain undulation height Δh, which is the difference between the high representative value and the low representative value, and calculates the terrain undulation height Δh and the hill correction value K ｈ and the terrain undulation height Δh, the hill correction value K ｈ FIG. 13 shows the relationship between the terrain undulation height Δh and the hill correction value K ｈ 10 is a graph showing the relationship between

[0052] Thereafter, if the height of the evaluation point is greater than the high representative value, that is, if the evaluation point is at the top, the correction value calculation device 2 calculates the terrain undulation height Δh and the hill fine correction value K ｈｆ and the terrain undulation height Δh, the hill fine correction value K ｈｆ Calculate the hill correction value K ｈ If the evaluation point is smaller than the low representative value, that is, if the evaluation point is in a valley, the correction value calculation device 2 adds the topographical relief Δh and the hill fine correction value K hf and the terrain undulation height Δh, the hill fine correction value K ｈｆ Calculate the hill correction value K ｈ FIG. 14 shows the relationship between the terrain relief height Δh and the hill fine correction value K ｈｆ 10 is a graph showing the relationship between the correction value K and the correction value calculation device 2.

[0053] When the terrain correction method is slope terrain correction, the correction value calculation device 2 calculates the planar distance d between the reference point and the evaluation target point and the slope angle θ between the reference point and the evaluation target point. ｍ and the slope correction value K ｓｐ Using the equation showing the relationship between the planar distance d between the base station and the evaluation point and the tilt angle θ between the reference point and the evaluation point, ｍ From the slope terrain correction value K ｓｐ 15 shows the planar distance d between the reference point and the evaluation point and the inclination angle θ between the reference point and the evaluation point. ｍ and the slope correction value K ｓｐ In the graph shown in FIG. 15, the horizontal axis indicates the inclination angle θ ｍ The unit is milliradian (mr).

[0054] In the embodiment described above, the terrain correction method determination device 1 determines the terrain correction method in the order of conditions C1, C2, C3, and C4. For example, when the terrain correction method is determined to be hilly terrain correction or slope correction, there are cases where land-sea mixed passage correction or mountain correction is actually required. However, in the embodiment described above, the terrain correction method determination device 1 determines whether the terrain correction method is land-sea mixed passage correction or mountain correction before determining whether the terrain correction method is hilly terrain correction or slope correction, thereby preventing the terrain correction method from being determined to be hilly terrain correction or slope correction when land-sea mixed passage correction or mountain correction is actually required.

[0055] The terrain correction method determination device 1 may determine the terrain correction method by changing the order of conditions C1, C2, C3, and C4. The terrain correction method determination device 1 may determine the terrain correction method by giving priority to the terrain correction method that has the largest absolute value of the correction value calculated by the terrain correction method. FIG. 16 is a diagram showing the possible values ​​of the correction values ​​calculated by each terrain correction method. The possible values, in descending order of absolute value, are multiple mountain correction, hilly terrain correction, isolated mountain correction, fine hilly correction, land-sea mixed passage correction, and slope terrain correction. The terrain correction method determination device 1 may determine the terrain correction method in the order of conditions C2, C3, C1, and C4. In other words, the terrain correction method determination device 1 may determine the terrain correction method in the following order: mountain correction, hilly terrain correction, land-sea mixed passage correction, or slope terrain correction.

[0056] There are other correction methods in addition to the above-described terrain correction methods, namely, multiple mountain correction, hilly terrain correction, isolated mountain correction, fine hill correction, land-sea mixed passage correction, and slope terrain correction. The terrain correction method determination device 1 may be configured to determine a new correction method. In this case, the order in which the new correction method is determined can be set so as not to make an erroneous determination of the characteristics of each terrain, or can be set in descending order of the absolute value of the possible correction values.

[0057] One embodiment of the present invention has been described in detail above with reference to the drawings, but the specific configuration is not limited to that described above, and various design changes and the like are possible within the scope that does not deviate from the gist of the present invention.

[0058] In this embodiment, the correction value calculation device 2 uses the Okumura-Hata formula as the propagation characteristic estimation formula, but is not limited to this. For example, the correction value calculation device 2 may calculate the received power by performing correction based on the correction value K on another propagation characteristic estimation formula.

[0059] The terrain correction method determination device 1 and the correction value calculation device 2 in the above-described embodiment may be implemented in part or in whole by a computer. In this case, a program for implementing this function may be recorded on a computer-readable recording medium, and the program may be loaded into a computer system and executed. Note that the term "computer system" as used herein includes an operating system (OS) and peripheral hardware. Furthermore, the term "computer-readable recording medium" refers to portable media such as flexible disks, optical magnetic disks, ROMs, and CD-ROMs, as well as storage devices such as hard disks built into computer systems. Furthermore, the term "computer-readable recording medium" may also include media that dynamically store programs for a short period of time, such as communication lines used when transmitting programs via networks such as the Internet or telephone lines, or media that store programs for a fixed period of time, such as volatile memory within a computer system that serves as a server or client. The program may also be designed to implement some of the above-described functions, or may be capable of implementing the above-described functions in combination with programs already stored in the computer system. Furthermore, part or all of the terrain correction method determination device 1 and the correction value calculation device 2 may be realized using a programmable logic device such as an FPGA (Field Programmable Gate Array).

[0060] 1 Terrain correction method determination device, 11 Terrain information acquisition unit, 12 Terrain information analysis unit, 13 Terrain correction method determination unit, 14 Output unit, 2 Correction value calculation device

Claims

1. A terrain correction method determination device which determines a terrain correction method to be one of land-sea mixed passage correction, mountain correction, hilly terrain correction, slope terrain correction, or no correction based on information on points between a reference point and an evaluation point, the device determining the terrain correction method to be the land-sea mixed passage correction when a ratio of the number of points determined to be water surface to the number of all points between the reference point and the evaluation point is equal to or greater than a certain level, determining the terrain correction method to be the mountain correction when an elevation difference between the reference point and a maximum elevation point having the highest elevation among all points is equal to or greater than a certain level and the planar distances between the maximum elevation point and the summit of a mountain are all equal to or less than a certain level, determining the terrain correction method to be the hilly terrain correction when the number of points which are undulating peaks among all points is equal to or greater than a certain level, determining the terrain correction method to be the slope terrain correction when a first angle, which is the angle between the reference point and the evaluation point, is equal to or greater than a certain level, a terrain correction method determining device that determines the terrain correction method to be no correction when the terrain correction method is not determined to be any of the land-sea mixed passage correction, the mountain correction, the hilly terrain correction, and the slope terrain correction.

2. A terrain correction method determination device as described in claim 1, which determines whether or not the terrain correction method is the land-sea mixed passage correction based on information about the location, and when it is determined that the terrain correction method is not to be the land-sea mixed passage correction, determines whether or not the terrain correction method is the mountain correction based on information about the location, when it is determined that the terrain correction method is not to be the mountain correction, determines whether or not the terrain correction method is the hilly terrain correction based on information about the location, when it is determined that the terrain correction method is not to be the hilly terrain correction, determines whether or not the terrain correction method is the slope terrain correction based on information about the location, and when it is determined that the terrain correction method is not to be the slope terrain correction, determines the terrain correction method to be no correction.

3. A terrain correction method determination device as described in claim 1, which determines whether or not the terrain correction method is to be the mountain correction based on information about the location, and when it is determined that the terrain correction method is not to be the mountain correction, determines whether or not the terrain correction method is to be the hilly terrain correction based on information about the location, when it is determined that the terrain correction method is not to be the hilly terrain correction, determines whether or not the terrain correction method is to be the land-sea mixed passage correction based on information about the location, when it is determined that the terrain correction method is not to be the land-sea mixed passage correction, determines whether or not the terrain correction method is to be the slope terrain correction based on information about the location, and when it is determined that the terrain correction method is not to be the slope terrain correction, determines the terrain correction method to be the no correction.

4. A terrain correction method determination device as described in claim 2, wherein when it is determined that the terrain correction method is not the land-sea mixed passage correction or the mountain correction, if the planar distance between the reference point and the evaluation point is less than or equal to a predetermined value, the terrain correction method is determined to be the no correction.

5. A terrain correction method determination device as described in claim 2, wherein when it is determined that the terrain correction method is not the land-sea mixed passage correction, the mountain correction, or the hilly terrain correction, and when the inclination angle between the reference point and the evaluation target point is within a predetermined range, the terrain correction method is determined to be no correction.

6. A method for determining a terrain correction method based on information on points between a reference point and an evaluation point, the method determining the terrain correction method to be one of land-sea mixed passage correction, mountain correction, hilly terrain correction, slope terrain correction, or no correction, the method determining the terrain correction method to be the land-sea mixed passage correction when a ratio of the number of points determined to be water surface to the number of all points between the reference point and the evaluation point is equal to or greater than a certain level, the method determining the terrain correction method to be the mountain correction when an elevation difference between the reference point and a maximum elevation point having the highest elevation among all points is equal to or greater than a certain level and the planar distances between the maximum elevation point and the summit of a mountain are all equal to or less than a certain level, the method determining the terrain correction method to be the hilly terrain correction when the number of points which are undulating peaks among all points is equal to or greater than a certain level, the method determining the terrain correction method to be the slope terrain correction when a maximum value of a ratio of a difference between an angle between the reference point and an inflection point among all points and the first angle to a first angle which is the angle between the reference point and the evaluation point is equal to or greater than a certain level, a terrain correction method determining method for determining no correction when the terrain correction method is not determined to be any of the land-sea mixed passage correction, the mountain correction, the hilly terrain correction, and the slope terrain correction.

7. A program for causing a computer to execute the terrain correction method determining method according to claim 6.

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