Propagation prediction system, propagation prediction method, and propagation prediction program

Abstract

To provide a propagation prediction system, a propagation prediction method, and a propagation prediction program, capable of accurately predicting the propagation loss between two wireless communication systems.SOLUTION: From among clutters placed between two base stations, a dominant clutter having the maximum elevation angle when the apex of the clutter is seen from each base station is selected. On the basis of the distance between each base station and each dominant clutter and the altitudes of each base station and each dominant clutter, a clutter loss of the propagation loss of a propagation path between the two base stations is calculated, the clutter loss being a component resulting from the dominant clutter. The components of the propagation loss excluding the clutter loss are approximated to a free space loss to predict the propagation loss. An output signal according to the propagation loss is output.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a propagation prediction system, a propagation prediction method, and a propagation prediction program, and is particularly suitable for use in a propagation prediction system, a propagation prediction method, and a propagation prediction program for predicting propagation loss between base stations of two wireless communication systems that use the same frequency. [Background technology]

[0002] The frequency band used in wireless communication is limited, and with the spread of mobile terminals that perform wireless communication, there is a demand for methods to use the frequency band more efficiently. From this perspective, technology to allocate the same frequency band to multiple wireless communication systems is being considered.

[0003] In order to prevent mutual interference, it is possible to perform control to stop at least a part of a secondary wireless communication system having a lower priority using the same frequency during the time and in the area in which a primary wireless communication system having a higher priority performs wireless communication. This control may be performed by predicting the interference power of each of the secondary base stations included in the secondary wireless communication system to the primary base station included in the primary wireless communication system. This interference power may be predicted based on the propagation loss between the primary base station and the secondary base station.

[0004] Examples of wireless communication systems with higher priority include wireless relay transmission systems for television broadcasting, wireless communication systems related to disaster prevention or defense, etc. Examples of wireless communication systems with lower priority include wireless communication using mobile phones or smartphones, especially wireless communication using carrier aggregation that bundles and utilizes multiple frequency bands.

[0005] In relation to the above, Non-Patent Document 1 (ITU-R (Radiocommunication Sector of International Telecommunication Union), "Recommendation ITU-R P.2108-0 (06 / 2017) Prediction of clutter loss P Series Radiowave propagation", [Online], June 20, 2017, Internet<URL:https: / / www.itu.int / dms_pubrec / itu-r / rec / p / R-REC-P.2108-0-201706-I!!PDF-E.pdf> ) discloses a calculation method for modeling an electromagnetic wave propagation environment and approximately predicting propagation loss due to clutter present in this propagation environment.

[0006] The standard model in Non-Patent Document 1 does not take into account the difference in altitude between the transmitting antenna, the receiving antenna, clutter, etc., and also produces a large error in the predicted propagation loss when clutter such as a building that is significantly taller than the antenna is present. [Prior art documents] [Non-patent literature]

[0007] [Non-Patent Document 1] ITU-R (Radiocommunication Sector of International Telecommunication Union), "Recommendation ITU-R P.2108-0 (06 / 2017) Prediction of clutter loss P Series Radiowave propagation", [Online], June 20, 2017, Internet<URL:https: / / www.itu.int / dms_pubrec / itu-r / rec / p / R-REC-P.2108-0-201706-I!!PDF-E.pdf> Summary of the Invention [Problem to be solved by the invention]

[0008] An object of the present disclosure is to accurately predict propagation loss. Other objects and novel features will become apparent from the description of this specification and the accompanying drawings. [Means for solving the problem]

[0009] The means for solving the problems will be explained below using the numbers used in the (Mode for carrying out the invention). These numbers are added to clarify the correspondence between the description in the (Claims) and the (Mode for carrying out the invention). However, these numbers should not be used to interpret the technical scope of the invention described in the (Claims).

[0010] According to one embodiment, the propagation prediction system (1) includes a calculation device (23) and an input / output device (22). The calculation device (23) estimates a propagation path between a primary base station (41) and a secondary base station (51) and predicts a propagation loss in the propagation path. The input / output device (22) outputs an output signal according to the propagation loss. The calculation device (23) calculates an elevation angle (θ θ ) of vertices (631, 641, 651) of clutter (63, 64, 65) as seen from the primary base station (41) among clutters (63, 64, 65) disposed between the primary base station (41) and the secondary base station (51). clut ) is the maximum of the first dominant clutter (64), and the elevation angle (θ clutThe calculation device (23) calculates components of the propagation loss attributable to the first dominant clutter (64) and the second dominant clutter (64, 65) as clutter losses (A) based on the distance from the primary base station (41) to the first dominant clutter (64), the distance from the first dominant clutter (64) to the second dominant clutter (64, 65), the distance from the second dominant clutter (64, 65) to the secondary base station (51), and the respective altitudes of the primary base station (41), the first dominant clutter (64), the second dominant clutter (64, 65), and the secondary base station (51). h The calculation device calculates the clutter loss (A h ) is approximated to the free space loss to predict the propagation loss.

[0011] According to one embodiment, the propagation prediction method includes estimating a propagation path between a primary base station (41) and a secondary base station (51), predicting a propagation loss of the propagation path, and outputting (S05) an output signal (14) according to the propagation loss. Predicting the propagation loss includes predicting an elevation angle (θ θ ) of a clutter apex (631, 641, 651) from the primary base station (41) among clutters (63, 64, 65) disposed between the primary base station (41) and the secondary base station (51), clut ) is maximized (S03), and from among the clutters (63, 64, 65) disposed between the primary base station (41) and the secondary base station (51), an elevation angle (θ clutThe prediction of the propagation loss further includes selecting (S03) a second dominant clutter (64, 65) for which the clutter loss (A) is maximum. The prediction of the propagation loss further includes determining components of the propagation loss attributable to the first dominant clutter (64) and the second dominant clutter (64, 65) as clutter losses (A) based on the distance from the primary base station (41) to the first dominant clutter (64), the distance from the first dominant clutter (64) to the second dominant clutter (64, 65), the distance from the second dominant clutter (64, 65) to the secondary base station (51), and the respective altitudes of the primary base station (41), the first dominant clutter (64), the second dominant clutter (64, 65), and the secondary base station (51). h ) (S04). The prediction of the propagation loss further includes calculating the clutter loss (A h ) is approximated to the free space loss (S04).

[0012] According to one embodiment, the propagation prediction program is for causing a computer to realize a predetermined function. The predetermined function includes estimating a propagation path between a primary base station (41) and a secondary base station (51), predicting a propagation loss of the propagation path, and outputting (S04) an output signal (14) according to the propagation loss. The prediction of the propagation loss includes estimating an elevation angle (θ θ θ ) of clutter vertices (631, 641, 651) as seen from the primary base station (41) among clutters (63, 64, 65) disposed between the primary base station (41) and the secondary base station (51), and outputting (S05) an output signal (14) according to the propagation loss. clut ) is maximized (S03), and from among the clutters (63, 64, 65) disposed between the primary base station (41) and the secondary base station (51), an elevation angle (θ clutThe prediction of the propagation loss further includes selecting (S03) a second dominant clutter (64, 65) for which the clutter loss (A) is maximum. The prediction of the propagation loss further includes determining a component of the propagation loss attributable to the first dominant clutter (64) and the second dominant clutter (64, 65) as a clutter loss (A) based on the distance from the primary base station (41) to the first dominant clutter (64), the distance from the first dominant clutter (64) to the second dominant clutter (64, 65), the distance from the second dominant clutter (64, 65) to the secondary base station (51), and the respective altitudes of the primary base station (41), the first dominant clutter (64), the second dominant clutter (64, 65), and the secondary base station (51). h ) (S04). The prediction of the propagation loss further includes calculating the clutter loss (A h ) is approximated to the free space loss (S04). Effect of the Invention

[0013] According to the embodiment, it is possible to predict the propagation loss with high accuracy. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a diagram showing an example of a configuration of a propagation prediction system according to an embodiment. [Figure 2A] FIG. 2A is a block circuit diagram showing an example of a configuration of a server according to an embodiment. [Figure 2B] FIG. 2B is a block circuit diagram showing an example of the configuration of the server shown in FIG. 2A from a functional point of view. [Diagram 3] FIG. 3 is a flowchart showing an example of a configuration of a propagation prediction method according to an embodiment. [Figure 4] FIG. 4 is a diagram for explaining a method for selecting dominant clutter in one embodiment. [Diagram 5] FIG. 5 is a diagram for explaining parameters derived from the positional relationship between the antenna and dominant clutter according to one embodiment. [Figure 6]FIG. 6 is a diagram for explaining a case where the dominant clutter corresponding to two antennas is the same in one embodiment. [Figure 7] FIG. 7 is a flowchart showing a modification of the propagation prediction method according to one embodiment. [Figure 8A] FIG. 8A is a flow chart illustrating another variation of the propagation prediction method according to one embodiment. [Figure 8B] FIG. 8B is a flowchart illustrating yet another variation of the propagation prediction method according to one embodiment. [Figure 8C] FIG. 8C is a flow chart illustrating a variation of the propagation prediction method according to one embodiment. [Figure 9] FIG. 9 is a diagram for explaining parameters derived from the positional relationship between two antennas at different altitudes and dominant clutter in one embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS With reference to the accompanying drawings, embodiments for implementing a propagation prediction system, a propagation prediction method, and a propagation prediction program according to the present invention will be described below.

[0016] (First embodiment) A configuration example of a propagation prediction system 1 according to an embodiment will be described with reference to Fig. 1. The propagation prediction system 1 is connected to a primary wireless communication system 4 and a secondary wireless communication system 5. Hereinafter, a case where the primary wireless communication system 4 and the secondary wireless communication system 5 are external to the propagation prediction system 1 will be described, but this embodiment does not necessarily exclude a case where the primary wireless communication system 4 and the secondary wireless communication system 5 are included in the propagation prediction system 1.

[0017] In this embodiment, a case will be described in which the primary wireless communication system 4 is a transmission / reception system for an FPU (Field Pickup Unit: wireless relay transmission device). The FPU is used, for example, for transmitting material for broadcasting a marathon. The primary wireless communication system 4 includes a primary base station 41 and a primary mobile station 42. The primary base station 41 and the primary mobile station 42 perform wireless communication using a predetermined frequency band allocated to the primary wireless communication system 4.

[0018] In addition, in this embodiment, a case where the secondary wireless communication system 5 is a cellular system will be described. The cellular system is used for wireless communication of, for example, mobile phones, smartphones, etc. The secondary wireless communication system 5 includes secondary base stations 51A, 51B, 51C, 51D, and 51E, a secondary operation server 50 that controls the secondary base stations 51A, 51B, 51C, 51D, and 51E, and secondary mobile stations (not shown). Hereinafter, when the secondary base stations 51A, 51B, 51C, 51D, and 51E are not distinguished from each other, they may be simply referred to as secondary base stations 51. In the example of FIG. 1, the total number of secondary base stations 51 is 5, but this embodiment is not limited to this total number. Furthermore, this embodiment is not limited to the total number of secondary mobile stations. The secondary base stations 51 and the secondary mobile stations perform wireless communication using a predetermined frequency band assigned to the secondary wireless communication system 5.

[0019] Here, in this embodiment, a case will be described in which the secondary wireless communication system 5 uses a frequency band that may interfere with the frequency band of the primary wireless communication system 4. In other words, a case will be described in which a radio signal emitted from the secondary base station 51 may reach the primary base station 41 as an interference wave 53. The primary wireless communication system 4 preferentially uses this frequency band for the secondary wireless communication system 5, and the secondary wireless communication system 5 uses the same frequency band within a range that does not cause interference with the primary wireless communication system 4. This frequency band may be, for example, a frequency band used in 5G (fifth generation mobile communication system).

[0020] The propagation prediction system 1 performs control to suppress interference from the secondary wireless communication system 5 to the primary wireless communication system 4 by predicting a propagation loss between the primary wireless communication system 4 and the secondary wireless communication system 5. First, the propagation prediction system 1 acquires operation information from each of the primary wireless communication system 4 and the secondary wireless communication system 5. Primary operation information 44 of the primary wireless communication system 4 may be provided to the propagation prediction system 1 from the primary base station 41, or may be provided to the propagation prediction system 1 from a primary operation server (not shown). Secondary operation information 54 of the secondary wireless communication system 5 is provided to the propagation prediction system 1 from a secondary operation server 50 included in the secondary wireless communication system 5.

[0021] The propagation prediction system 1 predicts the propagation loss of each secondary base station 51 based on these operation information, and performs control to limit the operation of the secondary wireless communication system 5 so that the interference power from the secondary base station 51 to the primary base station 41 is equal to or less than a desired threshold. This threshold may be determined based on a protection rule for protecting the primary wireless communication system 4. This control may also be performed by the propagation prediction system 1 generating and outputting an output signal 14 according to the propagation loss of each secondary base station 51, and the secondary operation server 50 stopping or operating each of the secondary base stations 51 based on the output signal 14.

[0022] To calculate this interference power, the propagation prediction system 1 calculates the propagation loss between the primary wireless communication system 4 and the secondary wireless communication system 5. To calculate this propagation loss, the propagation prediction system 1 refers to three-dimensional map information of the area where the primary wireless communication system 4 and the secondary wireless communication system 5 are located.

[0023] The three-dimensional map information includes position information indicating the horizontal position and altitude of clutter located between the primary wireless communication system 4 and the secondary wireless communication system 5. Clutter is a general term for objects other than terrain that exist on the surface of the Earth, such as buildings and vegetation. The position information of the clutter may indicate the horizontal position and altitude of a vertex at which diffraction of electromagnetic waves may occur in the clutter.

[0024] The three-dimensional map information further includes location information indicating the horizontal position and altitude of the primary wireless communication system 4, particularly the primary base station 41, and location information indicating the horizontal position and altitude of the secondary wireless communication system 5, particularly the secondary base station 51. The location information of the primary base station 41 may indicate the horizontal position and altitude of an antenna provided in the primary base station 41. The location information of the secondary base station 51 may also indicate the horizontal position and altitude of an antenna provided in the secondary base station 51.

[0025] The propagation prediction system 1 may hold in advance three-dimensional map information of the area in which the primary wireless communication system 4, the secondary wireless communication system 5, and the clutter are located, or may acquire the information from an external source as necessary.

[0026] When clutter exists that blocks a virtual straight line connecting the primary wireless communication system 4 and the secondary wireless communication system 5, propagation loss occurs due to the clutter. Such propagation loss is called clutter loss. In other words, the clutter loss of a certain clutter is the component of the propagation loss between the primary wireless communication system 4 and the secondary wireless communication system 5 that is due to the clutter.

[0027] With reference to the block circuit diagram of FIG. 2A, a configuration example of the propagation prediction system 1 according to an embodiment will be described. Each function of the propagation prediction system 1 may be realized using the configuration of the server 2. The server 2 includes a bus 21, an input / output device 22, a calculation device 23, a storage device 24, and an external storage device 25. The input / output device 22 inputs and outputs information, signals, and the like between the server 2 and a configuration outside the server 2. The calculation device 23 can realize a predetermined function by reading and executing a program stored in the storage device 24. The storage device 24 stores a program, data, and the like that the calculation device 23 reads in order to realize a predetermined function. The external storage device 25 can read a program, data, and the like from a recording medium 26, and can also write a program, data, and the like to the recording medium 26. The recording medium 26 may be non-transient. The input / output device 22, the calculation device 23, the storage device 24, and the external storage device 25 can communicate with each other via the bus 21.

[0028] With reference to the block circuit diagram of Fig. 2B, a configuration example of the server 2 shown in Fig. 2A will be described from a functional point of view. The server 2 includes a communication unit 201, a clutter selection unit 202, a propagation loss calculation unit 203, and a control unit 204. The communication unit 201 and the control unit 204 are each functional units realized by the input / output device 22, the arithmetic unit 23, and the storage device 24 working together. The clutter selection unit 202 and the propagation loss calculation unit 203 are each functional units realized by the arithmetic unit 23 and the storage device 24 working together. The functions of the communication unit 201, the clutter selection unit 202, the propagation loss calculation unit 203, and the control unit 204 will be described later.

[0029] An example of the configuration of the propagation prediction method according to an embodiment will be described with reference to the flowchart of Fig. 3. Note that the explanation of the example of the configuration of the propagation prediction method according to this embodiment is to explain the operation of the propagation prediction system 1 according to this embodiment, and is also to explain an example of the configuration of the propagation prediction program according to this embodiment.

[0030] When the propagation prediction method according to the present embodiment starts, step S01 is executed and three-dimensional map information is prepared in the storage device 24. As described above, this three-dimensional map information is for an area in which the primary wireless communication system 4 including the primary base station 41, the secondary wireless communication system 5 including the secondary base station 51, and clutter of the primary base station 41 and the secondary base station 51 are located. A part or all of the three-dimensional map information may be read from the outside by the communication unit 201 of the server 2 and stored in the storage device 24.

[0031] Step S02 is executed following step S01, and the communication unit 201 of the server 2 acquires primary operation information 44 from the primary base station 41 or the primary operation server, and acquires secondary operation information 54 from the secondary operation server 50. The primary operation information 44 may include various information indicating the horizontal position and altitude of the primary base station 41, the frequency band used by the primary wireless communication system 4, the strength of the wireless signal transmitted from the primary mobile station 42 and reaching the primary base station 41, the time period during which the primary wireless communication system 4 operates, and the like. Similarly, the secondary operation information 54 may include various information indicating the horizontal position and altitude of the secondary base station 51, the frequency band used by the secondary wireless communication system 5, the strength of the wireless signal transmitted from the secondary base station 51, the time period during which each of the secondary base stations 51 operates, and the like. Note that the information indicating the horizontal position and altitude of each of the primary base station 41 and the secondary base station 51 may be supplied from any one of the three-dimensional map information, the primary operation information 44, and the secondary operation information 54, or may be supplied in a duplicated manner from a plurality of them. Regarding the redundantly supplied operation information, the server 2 may appropriately determine which operation information to adopt, for example, based on a criterion such as adopting the most recent operation information.

[0032] Following step S02, step S03 is executed, in which the clutter selection unit 202 of the server 2 selects, from among the clutter located between the primary base station 41 and the secondary base station 51, a dominant clutter that has a dominant effect on the propagation loss between the primary base station 41 and the secondary base station 51.

[0033] An example of a method for selecting dominant clutter in one embodiment will be described with reference to Fig. 4. In the example of Fig. 4, three clutters 63, 64, and 65 exist between a first antenna 61 of the primary base station 41 and a second antenna 62 of the secondary base station 51. In the following description using the example of Fig. 4, it is assumed that the first antenna 61 and the second antenna 62 are at the same altitude, but the present embodiment is not limited to this example.

[0034] Each of the clutters 63, 64, and 65 is disposed so as to have a portion that blocks the imaginary straight path 612 connecting the first antenna 61 and the second antenna 62. In other words, each of the clutters 63, 64, and 65 is disposed between the first antenna 61 and the second antenna 62, and has a portion whose altitude is higher than the altitude of the first antenna 61 and the second antenna 62. At least, a direct wave cannot propagate along this imaginary straight path 612 between the first antenna 61 and the second antenna 62.

[0035] On the other hand, the electromagnetic waves emitted from the first antenna 61 may reach the second antenna 62 by being diffracted at the ends of the clutters 63, 64, and 65. Similarly, the electromagnetic waves emitted from the second antenna 62 may reach the first antenna 61 by being diffracted at the ends of the clutters 63, 64, and 65. However, propagation loss occurs due to the diffraction.

[0036] In the clutter model according to this embodiment, the clutters 63, 64, and 65 have vertices 631, 641, and 651, respectively. Although the propagation loss may be calculated by taking into consideration all the diffractions occurring at these vertices 631, 641, and 651, the amount of calculation required for this may become relatively large. Therefore, in this embodiment, an approximation is performed in which a first dominant clutter, the influence of which is predominantly due to the propagation loss to the first antenna 61, and a second dominant clutter, the influence of which is predominantly due to the propagation loss to the second antenna 62, are selected from the clutters disposed between the first antenna 61 and the second antenna 62, and the propagation loss caused by the remaining clutters is ignored.

[0037] In the example of FIG. 4, clutter 64 is selected as the first dominant clutter corresponding to the first antenna 61. The selection criterion is that the clutter has the maximum elevation angle when the vertices 631, 641, and 651 of the clutters 63, 64, and 65 are viewed from the first antenna 61. Here, a path 613 that is a straight line connecting the first antenna 61 and the vertex 631 of the clutter 63 is blocked by the clutter 64, and a path 615 that is a straight line connecting the first antenna 61 and the vertex 651 of the clutter 65 is also blocked by the clutter 64. On the other hand, a path 614 that is a straight line connecting the first antenna 61 and the vertex 641 of the clutter 64 is not blocked by the other clutters 63 and 65. Therefore, it is considered that the propagation loss of the electromagnetic wave transmitted and received by the first antenna 61 is larger when diffracted by the clutter 64 than when diffracted by the clutter 63 or 65.

[0038] Similarly, in the example of FIG. 4, clutter 65 is selected as the second dominant clutter corresponding to second antenna 62. The selection criterion is that the clutter has the maximum elevation angle when vertices 631, 641, and 651 of clutters 63, 64, and 65 are viewed from second antenna 62. Here, path 623, which is a straight line connecting second antenna 62 and vertex 631 of clutter 63, is blocked by clutters 64 and 65, and path 624, which is a straight line connecting second antenna 62 and vertex 641 of clutter 64, is blocked by clutter 65. On the other hand, path 615, which is a straight line connecting second antenna 62 and vertex 651 of clutter 65, is not blocked by other clutters 63 and 64. Therefore, it is considered that the propagation loss of the electromagnetic wave transmitted and received by second antenna 62 is larger when diffracted by clutter 65 than when diffracted by clutter 63 or 64.

[0039] Another criterion for selecting the dominant clutter for a given antenna may be to select the clutter with the largest clearance factor for that antenna, where the clearance factor is a parameter related to the loss of electromagnetic waves propagating through obstacles.

[0040] In this embodiment, among the propagation losses of the propagation path between the first antenna 61 and the second antenna 62, i.e., among the propagation losses of the propagation path between the primary base station 41 and the secondary base station 51, components excluding clutter losses caused by the first dominant clutter 64 and the second dominant clutter 65 are calculated and / or predicted by approximating them to free space losses. In the example of Fig. 4, when calculating the propagation loss in the case where the electromagnetic wave transmitted from the second antenna 62 passes through the path 625, the path 645, and the path 614 and is received by the first antenna 61, first, the propagation losses in the path 625, the path 645, and the path 614 are approximated to the propagation loss in free space over the distance of the path 612. In other words, it is estimated that the propagation path between the first antenna 61 and the second antenna 62 is free space over the distance of the path 612. Next, the propagation loss is approximately calculated by adding the clutter loss caused by the first dominant clutter 64 and the clutter loss caused by the second dominant clutter 65 to the free space loss for the distance of the path 612. As a modified example of the method for calculating the propagation loss through the paths 625, 645, and 614, the propagation loss through each of the paths 625, 645, and 614 may be the propagation loss in free space for the same distance. In this modified example, by selecting the first dominant clutter 64 corresponding to the first antenna 61 and the second dominant clutter 65 corresponding to the second antenna 62, it is estimated that the propagation path between the first antenna 61 and the second antenna 62 is a set of the paths 625, 645, and 614 that pass through the vertex 641 of the first dominant clutter 64 and the vertex 651 of the second dominant clutter 65.

[0041] In this manner, in this embodiment, the present invention is based on Non-Patent Document 1 (ITU-R (Radiocommunication Sector of International Telecommunication Union), "Recommendation ITU-R P.2108-0 (06 / 2017) Prediction of clutter loss P Series Radiowave propagation", [Online], June 20, 2017, Internet<URL:https: / / www.itu.int / dms_pubrec / itu-r / rec / p / R-REC-P.2108-0-201706-I!!PDF-E.pdf> ) is improved. By doing so, in this embodiment, it is possible to calculate and / or predict the path loss with high accuracy.

[0042] When a plurality of secondary base stations 51 are present, the clutter selection unit 202 selects a plurality of second dominant clutters corresponding to the plurality of secondary base stations 51, respectively.

[0043] In either case, the clutter selector 202 stores information representing the selected dominant clutter in the storage device 24.

[0044] Referring again to the flowchart of Fig. 3, step S04 is executed following step S03, and the propagation loss calculation unit 203 of the server 2 calculates the propagation loss at a frequency included in a frequency band in which interference with the primary base station 41 may occur, among the frequency bands used by the secondary base station 51. A first clutter loss, which is a component caused by a first dominant clutter, among the propagation loss between the primary base station 41 and the secondary base station 51, can be calculated based on the distance from the primary base station 41 to the first dominant clutter and the respective altitudes of the primary base station 41 and the first dominant clutter. Similarly, a second clutter loss, which is a component caused by a second dominant clutter, among the propagation loss between the primary base station 41 and the secondary base station 51, can be calculated based on the distance from the secondary base station 51 to the second dominant clutter and the respective altitudes of the secondary base station 51 and the second dominant clutter.

[0045] First, the clutter loss A h is defined by the following equation (1) in the standard model (suburban, city, trees, forest, dense city) of Non-Patent Document 1, and its unit is dB (decibels).

number

[0046] Referring to FIG. 5, parameters derived from the positional relationship between the first antenna 61 and the dominant clutter 64 according to an embodiment will be described. The altitude h of the antenna and the altitude R of the dominant clutter 64 shown in FIG. 5 are both altitudes with respect to the same horizontal plane. These altitudes may be defined as altitudes above sea level, or may be defined by adding the altitude of the ground surface to the height from the ground surface, but the present embodiment is not limited to these examples. In any case, in calculating the clutter loss and / or propagation loss in the present embodiment, since the difference between the altitude h and the altitude R is used, the altitude of the reference horizontal plane may be arbitrary.

[0047] (1a) formula is applicable when the condition of "h < R" is satisfied, that is, when the dominant clutter blocks the virtual straight line connecting the first antenna 61 and the second antenna 62. Also, (1b) formula is applicable when the condition of "h ≥ R" is satisfied, that is, when electromagnetic waves can propagate directly along this virtual straight line between the first antenna 61 and the second antenna 62. Hereinafter, the calculation method of (1a) formula will be described.

[0048] The parameter J(ν) used in (1a) formula is defined as in the following (2) formula.

Equation

[0049] The clearance coefficient ν used in (2) formula is defined as in the following (3) formula.

Equation

[0050] The frequency parameter K used in equation (3) nu is defined as the following equation (4).

number

[0051] The altitude difference h used in equation (3) dif is defined as the following equation (5).

number

[0052] Elevation angle θ used in equation (3) clut is defined as the following equation (6).

number

[0053] As described above, based on information on the positions and altitudes of the first antenna 61 and the dominant clutter 64, respectively, and on the values ​​of frequencies included in the frequency band used, it is possible to calculate the clutter loss due to the dominant clutter 64 in this frequency band. The clutter loss can be calculated in a similar manner for the dominant clutter corresponding to the second antenna 62.

[0054] Next, the propagation path from the primary base station 41 to the secondary base station 51 is approximated to free space. Alternatively, in the case of a modified example in which this propagation path is divided by a dominant clutter 64 and a second dominant clutter 65, the propagation path from the primary base station 41 to the first dominant clutter 64, the propagation path from the first dominant clutter 64 to the second dominant clutter 65, and the propagation path from the second dominant clutter 65 to the secondary base station 51 are each approximated to free space. The propagation loss in each of these free spaces, i.e., the free space loss, is defined as in the following equation (7).

number

[0055] Next, the free space loss L of each propagation path 0 By adding the clutter losses of the respective dominant clutters 64 and 65 to this, the overall propagation loss from the primary base station 41 to the secondary base station 51 can be predicted.

[0056] Step S05 is executed following step S04, and the control unit 204 of the server 2 generates an output signal 14 according to the propagation loss calculated in step S04 and outputs it to the secondary operation server 50. Here, a threshold for the propagation loss may be set so that when the propagation loss is smaller than a predetermined threshold, the interference power from the secondary base station 51 to the primary base station 41 exceeds another predetermined threshold. The interference power can be calculated from the power of the radio signal transmitted from the secondary base station 51 and the propagation loss.

[0057] The output signal 14 output by the control unit 204 may be a control signal for the secondary operation server 50 to stop the secondary base station 51 whose interference power to the primary base station 41 exceeds a predetermined protection standard. In other words, the secondary operation server 50 may stop the secondary base station 51 whose interference power to the primary base station 41 exceeds a predetermined protection standard in response to the output signal 14.

[0058] When step S05 is completed, the flowchart in FIG. 3 ends.

[0059] Another example of a method for selecting a dominant clutter in an embodiment will be described with reference to Fig. 6. The example in Fig. 6 is obtained by adding the following changes to the example in Fig. 4. That is, the altitude of clutter 65 is lowered. As a result, the second dominant clutter corresponding to the second antenna 62 is clutter 64 in the example in Fig. 6, whereas it was clutter 65 in the example in Fig. 4. On the other hand, the first dominant clutter corresponding to the first antenna 61 is clutter 64 in Fig. 6, as in the case of Fig. 4. That is, in the example in Fig. 6, the first dominant clutter and the second dominant clutter are the same clutter 64.

[0060] The calculation of the propagation loss of the dominant clutter in step S04 of the flowchart in Fig. 3 may be performed in a different manner depending on whether the first dominant clutter 64 and the second dominant clutter 65 are different clutters as shown in Fig. 4 or the first dominant clutter 64 and the second dominant clutter 65 are the same dominant clutter 64 as shown in Fig. 6. Such a modification will be described with reference to the flowchart in Fig. 7.

[0061] 7 starts, step S11 is executed, and the propagation loss calculation unit 203 judges whether the first dominant clutter and the second dominant clutter are the same clutter. To make this judgment, the propagation loss calculation unit 203 may read out the result of the selection of the dominant clutter stored in the storage device 24 by the clutter selection unit 202.

[0062] 4, if it is determined that the first dominant clutter 64 and the second dominant clutter 65 are different clutters from each other (No), step S11 is followed by step S12. In step S12, the path loss calculation unit 203 calculates the overall path loss between the first antenna 61 of the primary base station 41 and the second antenna 62 of the secondary base station 51 as follows.

[0063] That is, the first clutter loss and the second clutter loss caused by diffraction occurring in the first dominant clutter 64 and the second dominant clutter 65 are calculated using the formulas (1a) to (7), respectively, as described above.

[0064] When step S12 is completed, the flowchart in FIG. 7 ends, and the process proceeds to step S05 in the flowchart in FIG.

[0065] 7, if it is determined that the first dominant clutter 64 and the second dominant clutter 64 are the same dominant clutter 64 (Yes), as illustrated in FIG 6, step S11 is followed by step S13. In step S13, the path loss calculation unit 203 calculates the overall path loss between the first antenna 61 of the primary base station 41 and the second antenna 62 of the secondary base station 51 as follows.

[0066] That is, the clutter loss of the same dominant clutter 64 is calculated based on the shorter of a first distance from the primary base station 41 to the dominant clutter 64 and a second distance from the secondary base station 51 to the dominant clutter 64.

[0067] Next, the propagation path from the primary base station 41 to the first dominant clutter 64 and the propagation path from the first dominant clutter 64 to the second antenna 62 are each approximated to a free space. The free space loss in each of these free spaces is defined as in the above-mentioned equation (7).

[0068] Next, the free space loss L of each propagation path 0 By adding the clutter loss of the first dominant clutter 64 to this, the overall propagation loss from the primary base station 41 to the secondary base station 51 can be predicted.

[0069] When step S13 is completed, the flowchart in FIG. 7 ends, and the process proceeds to step S05 in the flowchart in FIG.

[0070] In this way, depending on whether or not the process of the flowchart in FIG. 7 is performed, when the dominant clutter corresponding to the first antenna 61 and the second antenna 62 is the same clutter, it is possible to select whether the clutter loss caused by this dominant clutter is taken into account once or twice in the overall propagation loss between the first antenna 61 and the second antenna 62. This selection may be made according to the shape of the apex of the dominant clutter. As an example, when the dominant clutter is a rectangular parallelepiped building or the like and there is a sufficiently long distance between the apex facing the first antenna 61 and the apex facing the second antenna 62, there is a possibility that the accuracy of predicting the propagation loss is higher when the process of the flowchart in FIG. 7 is not performed. On the other hand, when the distance between the apex facing the first antenna 61 and the apex facing the second antenna 62 is sufficiently short, there is a possibility that the accuracy of predicting the propagation loss is higher when the process of the flowchart in FIG. 7 is performed.

[0071] Another modified example of the propagation prediction method according to an embodiment will be described with reference to the flowchart in Fig. 8A. In this modified example, when calculating the clutter loss caused by the dominant clutter in step S04 of the flowchart in Fig. 3 or step S12 or step S13 of the flowchart in Fig. 7, the altitude of the dominant clutter is replaced with another lower altitude if a predetermined condition is satisfied. In this way, it is possible to simulate propagation due to diffraction on the side surface of the dominant clutter, which is not taken into account in the standard model of Non-Patent Document 1.

[0072] When the flowchart of Fig. 8A starts, step S21 is executed, and the propagation loss calculation unit 203 judges whether the height of the dominant clutter is equal to or higher than a threshold. To make this judgment, the propagation loss calculation unit 203 may read out the selection result of the dominant clutter stored in the storage device 24 by the clutter selection unit 202 in step S03 of the flowchart of Fig. 3. Alternatively, the propagation loss calculation unit 203 may read out the height of the dominant clutter stored in a database (not shown) or the storage device 24.

[0073] If the result of the determination in step S21 is that the altitude of the dominant clutter selected in step S03 is equal to or higher than a predetermined threshold (Yes), step S21 is followed by step S22. In step S22, the propagation loss calculation unit 203 replaces the altitude of this dominant clutter with this threshold. When step S22 is completed, the flowchart in Fig. 8A ends, and the process returns to step S04 in the flowchart in Fig. 3 or step S12 or step S13 in the flowchart in Fig. 7, where the propagation loss calculation unit 203 calculates the clutter loss and the propagation loss using the replaced altitude as the altitude of the dominant clutter.

[0074] If the result of the judgment in step S21 is that the altitude of the dominant clutter selected in step S03 is less than the predetermined threshold value (No), the flowchart in FIG. 8A ends, and the process returns to step S04 in the flowchart in FIG. 3 or step S12 or step S13 in the flowchart in FIG. 7, and the propagation loss calculation unit 203 calculates the clutter loss and the propagation loss using the unreplaced altitude as the altitude of the dominant clutter.

[0075] In this way, by using an appropriate altitude threshold as the altitude threshold of the dominant clutter when performing the process shown in the flowchart of Fig. 8A, it is possible to simulate, in addition to propagation via diffraction at the apex of the dominant clutter, propagation due to diffraction at the side surface of the dominant clutter, which is not taken into account in the standard model of Non-Patent Document 1. This process requires a relatively small amount of calculation as a method for calculating propagation loss due to diffraction at the side surface of the dominant clutter, and further leads to accurate prediction of propagation loss.

[0076] With reference to the flowchart of Fig. 8B, a further modified example of the propagation prediction method according to an embodiment will be described. In this modified example, similar to the case of Fig. 8A, when calculating the clutter loss caused by the dominant clutter in step S04 of the flowchart of Fig. 3 or step S12 or step S13 of the flowchart of Fig. 7, the altitude of the dominant clutter is replaced with another lower altitude if a predetermined condition is satisfied. In this way, it is possible to simulate propagation due to diffraction on the side surface of the dominant clutter, which is not taken into account in the standard model of Non-Patent Document 1.

[0077] When the flowchart of Fig. 8B starts, step S31 is executed, and the propagation loss calculation unit 203 judges whether the altitude difference between the dominant clutter and the corresponding base station is equal to or greater than a threshold. To make this judgment, the propagation loss calculation unit 203 may read out the selection result of the dominant clutter stored in the storage device 24 by the clutter selection unit 202 in step S03 of the flowchart of Fig. 3. The propagation loss calculation unit 203 may also read out the respective altitudes of the primary base station 41, the secondary base station 51, and the dominant clutter stored in the database or the storage device 24.

[0078] If the result of the determination in step S31 is that the altitude difference between the dominant clutter selected in step S03 and the corresponding base station is equal to or greater than a predetermined threshold (Yes), step S31 is followed by step S32. In step S32, the propagation loss calculation unit 203 replaces the altitude of this dominant clutter with a value that makes this altitude difference equal to the threshold. When step S32 is completed, the flowchart in Fig. 8B ends, and the process returns to step S04 in the flowchart in Fig. 3 or step S12 or step S13 in the flowchart in Fig. 7, where the propagation loss calculation unit 203 calculates the clutter loss and the propagation loss using the replaced altitude as the altitude of the dominant clutter.

[0079] If the result of the judgment in step S31 is that the altitude of the dominant clutter selected in step S03 is less than the predetermined threshold value (No), the flowchart in FIG. 8B ends, and the process returns to step S04 in the flowchart in FIG. 3 or step S12 or step S13 in the flowchart in FIG. 7, and the propagation loss calculation unit 203 calculates the clutter loss and the propagation loss using the unreplaced altitude as the altitude of the dominant clutter.

[0080] In this way, when performing the process shown in the flowchart of Fig. 8B, by using an appropriate altitude threshold as the threshold for the altitude of the dominant clutter, as in the case of Fig. 8A, it is possible to simulate, in addition to propagation via diffraction at the apex of the dominant clutter, propagation due to diffraction at the side surface of the dominant clutter, which is not taken into account in the standard model of Non-Patent Document 1. This process requires a relatively small amount of calculation as a method for calculating propagation loss due to diffraction at the side surface of the dominant clutter, and further leads to accurate prediction of propagation loss.

[0081] In the modification example described with reference to Figures 8A and 8B, when the altitude of the dominant clutter is replaced with another lower altitude to calculate the clutter loss, a similar replacement is also performed when selecting the dominant clutter as a preliminary step. This will be described with reference to Figure 8C.

[0082] In this modification, when step S03 in the flowchart of Fig. 3 is executed, the flowchart of Fig. 8C is started. First, in step S41, the clutter selection unit 202 refers to map information, lists information on clutter that exists between the primary base station 41 and the secondary base station 51, and initializes the order in which the clutter is processed. The order in which the clutter is processed may be, for example, in order of proximity to the primary base station. Also, an argument representing the order is initialized to zero, and an argument representing the total number of listed clutters is stored.

[0083] In step S42, the clutter selection unit 202 reads the next clutter information from the listed clutter information. At this time, an argument indicating the order of processing the clutter is incremented. In step S43, it is determined whether a value obtained by subtracting the reference altitude from the altitude of the clutter whose information has been read is greater than a predetermined threshold value. Here, if the first antenna 61 of the primary base station 41 and the second antenna 62 of the secondary base station 51 have the same altitude, the reference altitude is equal to this altitude.

[0084] When the first antenna 61 and the second antenna 62 have different altitudes, the altitude is the altitude of the point that is included in the imaginary line connecting the first antenna 61 and the second antenna 62 and is closest to the apex of the clutter. In other words, the value obtained by subtracting the reference altitude from the altitude of the clutter is equal to the vertical length from the apex of the clutter to the imaginary line. When the first antenna 61 and the second antenna 62 have different altitudes, the altitude of the clutter is similarly replaced when calculating the clutter loss due to the dominant clutter. The details will be described later as another embodiment.

[0085] In either case, if the result of the determination is that the value obtained by subtracting the reference altitude from the altitude of the clutter whose information has been read is greater than the predetermined threshold (Yes), the altitude of the clutter is replaced with another lower altitude in step S44, and the process proceeds to step S45. Conversely, if the value obtained by subtracting the reference altitude from the altitude of the clutter whose information has been read is not greater than the predetermined threshold (No), step S44 is not executed and the process proceeds to step S45.

[0086] In step S45, it is determined whether information on all clutters has been read. In other words, it is determined whether the argument representing the order in which the clutters are processed has reached the argument representing the total number of clutters listed. If the result of the determination is that information on all clutters has been read (Yes), the process proceeds to step S46. Conversely, if there is still clutter for which information has not been read (No), the process returns to step S42.

[0087] In step S46, the clutter selection unit 202 extracts dominant clutter. This operation is as shown in step S03 in the flowchart of Fig. 3. When step S46 is completed, the flowchart of Fig. 8C ends, and the process proceeds to step S04 in the flowchart of Fig. 3.

[0088] In this modification, by performing the above-described processing, it is possible to achieve consistency between the processing for extracting dominant clutter and the processing for calculating clutter loss resulting from dominant clutter by similarly replacing the clutter heights in both the processing.

[0089] (Second embodiment) In the above-mentioned first embodiment, a case has been described in which the altitudes of the first antenna 61 and the second antenna 62 are the same as each other, as exemplified in Fig. 4 and Fig. 6. This configuration conforms to the standard model of Non-Patent Document 1. In the second embodiment, a method of predicting propagation loss taking into account the altitude difference between the first antenna 61 and the second antenna 62 will be described.

[0090] With reference to Fig. 9, a parameter derived from the positional relationship between two antennas 61 and 62 at different altitudes and a dominant clutter 66 in one embodiment will be described. In the example of Fig. 9, the altitude h eb is the altitude R of the clutter 66 where the effect of the propagation loss on the first antenna 61 is dominant. e Higher, the altitude of this dominant clutter 66 R e is the altitude h of the second antenna 62 et Higher. Now, these altitudes h eb , h et , R e Each of the above is an altitude based on the same horizontal plane. This reference may be the height above sea level or the height from the ground surface, as in the case of FIG. 5, but the present embodiment is not limited to these examples.

[0091] Altitude h of the first antenna 61 eb and the altitude of the second antenna 62 is h et When the altitudes R of the dominant clutter 66 are different, the imaginary line connecting the first antenna 61 and the second antenna 62 is not horizontal. e is the altitude h of the first antenna 61 eb Even if the altitude h of the first antenna 61 is lower, depending on the position of the dominant clutter 66, it may block the virtual straight path 612 as shown in FIG. 9. Even in this case, the electromagnetic wave radiated from the second antenna 62 can reach the first antenna 61 via a path 616 connecting the first antenna 61 and a vertex 661 of the dominant clutter, and a path 626 connecting the vertex 661 and the second antenna 62. In this embodiment, the formula used to calculate the propagation loss in the first embodiment is corrected as follows, so that the altitude h of the first antenna 61 can be calculated as follows: eb and the altitude of the second antenna 62 is h et This makes it possible to calculate the propagation loss even when the antennas are different.

[0092] The definition of the clearance coefficient v is corrected from equation (3) used in the first embodiment to the following equation (8).

number

[0093] (8) The length h' of the formula dif 9, is the vertical length from the vertex 661 of the dominant clutter 66 to the imaginary line connecting the first antenna 61 and the second antenna 62, and its unit is m. dif The definition of h is given by the formula (5) used in the first embodiment. dif The definition of is corrected as shown in the following equation (9).

number

[0094] Angle θ in Eq. (9) tr is defined as the following equation (10).

number

[0095] Angle θ' in equation (8) clut9, is the angle between an imaginary straight path 612 connecting the first antenna 61 and the second antenna 62 and an imaginary straight path 616 connecting the first antenna 61 and the apex 661 of the dominant clutter 66, and is expressed in degrees. clut The definition of is the elevation angle θ clut The definition of is corrected as shown in the following equation (11).

number

[0096] As a result of the above correction, the application condition of equation (1) is also corrected to the following equation (12).

number

[0097] By correcting each definition as described above, according to this embodiment, it is possible to accurately calculate the propagation loss between the primary base station 41 and the secondary base station 51, where the altitudes of the antennas 61, 62 are different, as in the case of the first embodiment.

[0098] (Third embodiment) In this embodiment, as a modification of the first and second embodiments, the following changes are made. That is, when the propagation loss between the primary base station 41 and the secondary base station 51 includes a first clutter loss, which is a component caused by a first dominant clutter, and a second clutter loss, which is a component caused by a second dominant clutter, the propagation loss is calculated by considering only one of the first clutter loss and the second clutter loss. At this time, the other of the first clutter loss and the second clutter loss, which was not considered in the propagation loss calculation, is replaced with a free space loss when the propagation loss is calculated. The free space loss is defined as in the above-mentioned formula (7).

[0099] In this embodiment, the propagation loss is calculated by considering the smaller of the first clutter loss and the second clutter loss and replacing the larger loss with the free space loss.

[0100] In a modification of this embodiment, on the other hand, the larger of the first clutter loss and the second clutter loss is considered, and the smaller loss is replaced with the free space loss to calculate the propagation loss.

[0101] In this embodiment, by performing the calculations as described above, it is possible to accurately predict the propagation loss, particularly when setting a margin for the signal output when the primary wireless communication system 4 and the secondary wireless communication system 5 share a frequency.

[0102] Although the invention made by the inventor has been specifically described above based on the embodiment, it goes without saying that the present invention is not limited to the above embodiment and can be modified in various ways without departing from the gist of the invention. Furthermore, the respective features described in the above embodiment can be freely combined within the scope of technical compatibility.

[0103] As a modification of each of the above-mentioned embodiments, the clutter loss may be calculated using three-dimensional map information that is divided into a plurality of regions and has altitude information registered for each region. For example, mesh-shaped three-dimensional map information divided horizontally at a predetermined unit length may be used. The altitude information registered for these regions is the representative altitude of each region, and may be, for example, the average altitude within the region. Selection of dominant clutter and calculation of clutter loss caused by dominant clutter may be performed assuming that clutter of the representative altitude exists at a representative position of each region, for example, at the geometric center position. That is, a region in which the elevation angle of the representative altitude of the region as seen from the antenna is maximum may be selected as the dominant region, and the component of the propagation loss caused by the dominant region may be calculated based on the distance from the antenna to the representative position of the dominant region, the height of the antenna, and the representative altitude. Also, the area in which the primary base station 41 and the secondary base station 51 are located may be divided horizontally into a plurality of meshes at a predetermined unit length, and the average value of the altitude of the clutter included in each mesh may be treated as the altitude of each mesh. In this case, in step S03 of the flowchart in Fig. 3, the height of the clutter located between the primary base station 41 and the secondary base station 51 can be replaced with the height of the mesh located between the primary base station 41 and the secondary base station 51, and the dominant mesh can be selected instead of the dominant clutter. Also, in step S04 of the flowchart in Fig. 3, the height of the dominant clutter can be replaced with the height of the dominant mesh to calculate the clutter loss and the propagation loss.

[0104] Although a clutter model having an apex at the top position has been described, the present disclosure is not limited to this, and may be a structure formed in a rectangular parallelepiped shape, for example, a building. In this case, the geometric center position of the structure may be used as the position of the clutter, or the position of the wall surface closer to the antenna may be used. Furthermore, a model may be adopted in which the apex of the clutter is located directly above the position of the clutter and has the height of the clutter.

[0105] 3, the control unit 204 may generate and output an output signal 14 for displaying the propagation loss calculated in step S04 on an arbitrary display device. The user of the propagation prediction system 1 may control the secondary base station 51 via the secondary operation server 50 in accordance with the propagation loss displayed on the display device. [Explanation of symbols]

[0106] 1. Propagation prediction system 14 Output Signal 2 Server 21 Bus 22 Input / Output Devices 23 Arithmetic unit 24 Storage device 25 External storage device 26 Recording media 201 Communications Department 202 Clutter Selection Section 203 Propagation loss calculation unit 204 Control section 4 Primary Radio Communication System 41 Primary base station 42 Primary Mobile Station 44 Primary Operational Information 5 Secondary wireless communication system 50 Secondary production servers 51, 51A~51E Secondary base station 53 Interference Wave 54 Secondary Operation Information 61, 62 Antenna 612~616, 623~626, 645 Pass 63, 64, 65, 66 Clutter 631, 641, 651, 661 Vertex

Claims

1. A calculation device that estimates a propagation path between a primary base station and a secondary base station and predicts a propagation loss in the propagation path; an input / output device that outputs an output signal according to the propagation loss; Equipped with The computing device includes: selecting, from among the clutters located between the primary base station and the secondary base station, a first dominant clutter having a maximum elevation angle when the clutter apex is viewed from the primary base station, and a second dominant clutter having a maximum elevation angle when the clutter apex is viewed from the secondary base station; calculating, as a clutter loss, a component of the propagation loss caused by the first dominant clutter and the second dominant clutter based on a distance from the primary base station to the first dominant clutter, a distance from the first dominant clutter to the second dominant clutter, a distance from the second dominant clutter to the secondary base station, and respective altitudes of the primary base station, the first dominant clutter, the second dominant clutter, and the secondary base station; predicting the propagation loss by approximating a component of the propagation loss excluding the clutter loss to a free space loss; The input / output device outputs the output signal for deactivating the secondary base station when the propagation loss is lower than a predetermined threshold. Propagation prediction system.

2. 2. The propagation prediction system according to claim 1, The computing device includes: calculating a first clutter loss attributable to the first dominant clutter among the clutter losses based on a first distance from the primary base station to the first dominant clutter and the altitudes of the primary base station and the first dominant clutter; Calculating a second clutter loss caused by the second dominant clutter among the clutter losses based on a second distance from the secondary base station to the second dominant clutter and the altitudes of the secondary base station and the second dominant clutter. Propagation prediction system.

3. 3. The propagation prediction system according to claim 2, The propagation loss is predicted by replacing the larger component of the clutter loss, the first clutter loss and the second clutter loss, with a free space loss. Propagation prediction system.

4. 3. The propagation prediction system according to claim 2, The propagation loss is predicted by replacing the smaller component of the first clutter loss and the second clutter loss, which are components of the clutter loss, with a free space loss. Propagation prediction system.

5. 2. The propagation prediction system according to claim 1, When the first dominant clutter and the second dominant clutter are the same clutter, the calculation device a first distance from the primary base station to the same clutter and a second distance from the secondary base station to the same clutter, the shorter of these; an altitude of a base station among the primary base station and the secondary base station, the base station having a shorter distance to the same clutter than the primary base station and the secondary base station; the height of the same clutter; The clutter loss is calculated based on Propagation prediction system.

6. The propagation prediction system according to any one of claims 1 to 5, The computing device includes: when selecting the first dominant clutter and the second dominant clutter, selecting from the clutters located between the primary base station and the secondary base station, the first dominant clutter having a maximum elevation angle when a peak of the clutter is seen from the primary base station and the second dominant clutter having a maximum elevation angle when a peak of the clutter is seen from the secondary base station when the altitude of the clutter is equal to or greater than a predetermined altitude threshold is replaced with the altitude threshold, When a first altitude of the first dominant clutter is equal to or greater than the altitude threshold, the first altitude is replaced with the altitude threshold to calculate the clutter loss; When the second height of the second dominant clutter is equal to or greater than the height threshold, the second height is replaced with the height threshold to calculate the clutter loss. Propagation prediction system.

7. The propagation prediction system according to any one of claims 1 to 5, The computing device includes: when selecting the first dominant clutter, for each of the clutters located between the primary base station and the secondary base station, when an altitude difference between the clutter and the primary base station is equal to or greater than a predetermined altitude difference threshold, selecting from the clutter the first dominant clutter which has a maximum elevation angle when a vertex of the clutter is viewed from the primary base station when the altitude of the clutter is replaced with a value that makes the altitude difference equal to the altitude difference threshold; When a first altitude difference between the first dominant clutter and the primary base station is equal to or greater than the altitude difference threshold, replace the altitude of the first dominant clutter with a value that makes the first altitude difference equal to the altitude difference threshold to calculate the clutter loss; when selecting the second dominant clutter, for each of the clutters located between the primary base station and the secondary base station, when an altitude difference between the clutter and the secondary base station is equal to or greater than a predetermined altitude difference threshold, selecting from the clutter the second dominant clutter which has a maximum elevation angle when a peak of the clutter is seen from the secondary base station when the altitude of the clutter is replaced with a value that makes the altitude difference equal to the altitude difference threshold; When a second altitude difference between the second dominant clutter and the secondary base station is equal to or greater than the altitude difference threshold, the altitude of the second dominant clutter is replaced with a value that makes the second altitude difference equal to the altitude difference threshold to calculate the clutter loss. Propagation prediction system.

8. The propagation prediction system according to any one of claims 1 to 5, The computing device includes: when selecting the first dominant clutter and the second dominant clutter, when a vertical length from an apex of the clutter to a virtual straight line connecting the primary base station and the secondary base station is equal to or greater than a predetermined length threshold for each of the clutters located between the primary base station and the secondary base station, selecting from the clutters the first dominant clutter for which the elevation angle when the apex of the clutter is seen from the primary base station and the second dominant clutter for which the elevation angle when the apex of the clutter is seen from the secondary base station is maximum when the altitude of the clutter is replaced with an altitude at which the length becomes the length threshold, when a first length in a vertical direction from a first vertex of the first dominant clutter to the virtual straight line is equal to or greater than a predetermined length threshold, replacing an altitude of the first dominant clutter with an altitude at which the first length becomes the length threshold, thereby calculating the clutter loss; When a second length in a vertical direction from a second apex of the second dominant clutter to the virtual straight line is equal to or greater than the length threshold, the altitude of the second dominant clutter is replaced with an altitude at which the second length becomes the length threshold to calculate the clutter loss. Propagation prediction system.

9. The propagation prediction system according to any one of claims 1 to 8, The computing device includes: an area in which the first dominant clutter and the second dominant clutter are located is divided into a plurality of regions, and map information is referred to in which a representative position and a representative altitude of the representative position are registered for each of the plurality of regions; From among the areas blocking a virtual straight line connecting the primary base station and the secondary base station, a first dominant area in which the elevation angle when viewing a virtual apex at a representative altitude of a representative position of the area from the primary base station is maximum is selected as the first dominant clutter, and a second dominant area in which the elevation angle when viewing a virtual apex at a representative altitude of a representative position of the area from the secondary base station is maximum is selected as the second dominant clutter. Propagation prediction system.

10. The propagation prediction system according to any one of claims 1 to 8, The calculation device predicts the propagation loss based on first operation information including information representing a position, an altitude, and a frequency band used by the primary base station, and second operation information including information representing a position, an altitude, and a frequency band used by the secondary base station. Propagation prediction system.

11. estimating a propagation path between a primary base station and a secondary base station and predicting a propagation loss in the propagation path; outputting an output signal according to the propagation loss; Including, Predicting the propagation loss comprises: selecting a first dominant clutter having a maximum elevation angle when a vertex of the clutter is seen from the primary base station, from among the clutters disposed between the primary base station and the secondary base station; selecting, from among the clutters disposed between the primary base station and the secondary base station, a second dominant clutter having a maximum elevation angle when the apex of the clutter is seen from the secondary base station; calculating, as a clutter loss, a component of the propagation loss caused by the first dominant clutter and the second dominant clutter based on a distance from the primary base station to the first dominant clutter, a distance from the first dominant clutter to the second dominant clutter, a distance from the second dominant clutter to the secondary base station, and respective altitudes of the primary base station, the first dominant clutter, the second dominant clutter, and the secondary base station; Of the propagation loss, components other than the clutter loss are approximated to free space loss. Including, The outputting step includes: outputting the output signal for deactivating the secondary base station when the path loss is lower than a predetermined threshold. Includes Propagation prediction methods.

12. A propagation prediction program for causing a computer to realize a predetermined function, The predetermined function is Assuming a propagation path between a primary base station and a secondary base station, and predicting a propagation loss in the propagation path; outputting an output signal according to the propagation loss; Including, Predicting the propagation loss comprises: selecting a first dominant clutter having a maximum elevation angle when a vertex of the clutter is seen from the primary base station, from among the clutters disposed between the primary base station and the secondary base station; selecting, from among the clutters disposed between the primary base station and the secondary base station, a second dominant clutter having a maximum elevation angle when the apex of the clutter is seen from the secondary base station; calculating, as a clutter loss, a component of the propagation loss caused by the first dominant clutter and the second dominant clutter based on a distance from the primary base station to the first dominant clutter, a distance from the first dominant clutter to the second dominant clutter, a distance from the second dominant clutter to the secondary base station, and respective altitudes of the primary base station, the first dominant clutter, the second dominant clutter, and the secondary base station; predicting the propagation loss by approximating a component of the propagation loss excluding the clutter loss to a free space loss; Including, The outputting step includes: outputting the output signal for deactivating the secondary base station when the path loss is lower than a predetermined threshold. Includes Propagation prediction program.

Images