WO2021261031A1

WO2021261031A1 - Propagation prediction system, propagation prediction method, and recording medium storing propagation prediction program

Info

Publication number: WO2021261031A1
Application number: PCT/JP2021/010539
Authority: WO
Inventors: 威生藤井; 直宮本; 啓太片桐; 宏一安達; 光哉佐藤
Original assignee: 国立大学法人電気通信大学
Priority date: 2020-06-25
Filing date: 2021-03-16
Publication date: 2021-12-30

Abstract

According to the present invention, the propagation loss between two wireless communication systems is accurately predicted. 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 thereof, 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.

Description

A recording medium containing a propagation prediction system, a propagation prediction method, and a propagation prediction program.

The present invention relates to a propagation prediction system, a propagation prediction method, and a recording medium containing a propagation prediction program, and in particular, a propagation prediction system for predicting propagation loss between base stations of two wireless communication systems using the same frequency, propagation. It can be suitably used as a recording medium in which a prediction method and a propagation prediction program are stored.

The frequency band used in wireless communication is finite, and with the spread of mobile terminals that perform wireless communication, there is a demand for a method of using the frequency band more efficiently. From this point of view, a technique for allocating the same frequency band to a plurality of wireless communication systems is being studied.

Here, in order to prevent mutual interference, control is performed to stop at least a part of the lower priority secondary radio communication system using the same frequency at the time and region where the higher priority primary radio communication system performs wireless communication. Can be considered. This control may be performed by predicting the interference power to the primary base station included in the primary wireless communication system for each of the secondary base stations included in the secondary wireless communication system. This interference power may be predicted based on the propagation loss between the primary base station and the secondary base station.

Examples of wireless communication systems with higher priority include wireless relay transmission systems for television broadcasting and wireless communication systems related to disaster prevention or defense. Further, as an example of a wireless communication system having a lower priority, wireless communication using a mobile phone, a smartphone, or the like, particularly wireless communication by carrier aggregation that bundles and uses a plurality of frequency bands can be mentioned.

In relation to the above, Non-Patent Document 1 (ITU-R (Radiocommunication Sector of International Telecommunication Union), "Recommunication ITU-R P.2108-0 (06/2017) Redocommunication Section ], 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 the propagation environment of electromagnetic waves and approximately predicting the propagation loss due to clutter existing in this propagation environment.

In the standard model of Non-Patent Document 1, the elevation difference of the transmitting side antenna, the receiving side antenna, the clutter, etc. is not taken into consideration, and the propagation predicted when there is a clutter such as a building significantly higher than the antenna. The loss error increases.

The purpose of this disclosure is to accurately predict propagation loss. Other issues and novel features will become apparent from the description and accompanying drawings herein.

According to one embodiment, the propagation prediction system includes an arithmetic unit and an input / output unit. The arithmetic unit estimates the propagation path between the primary base station and the secondary base station, and predicts the propagation loss in the propagation path. The input / output device outputs an output signal according to the propagation loss. Among the clutters arranged between the primary base station and the secondary base station, the arithmetic unit is the first dominant clutter that has the maximum elevation angle when the apex of the clutter is seen from the primary base station, and the clutter from the secondary base station. Select the second dominant clutter that has the maximum elevation angle when looking at the apex of. The arithmetic unit is the distance from the primary base station to the first dominant clutter, the distance from the first dominant clutter to the second dominant clutter, the distance from the second dominant clutter to the secondary base station, and the primary base. Based on the respective altitudes of the station, the first dominant clutter, the second dominant clutter, and the secondary base station, the component of the propagation loss caused by the first dominant clutter and the second dominant clutter is calculated as the clutter loss. do. The arithmetic unit predicts the propagation loss by approximating the component of the propagation loss excluding the clutter loss to the free space loss.

According to one embodiment, the propagation prediction method estimates the propagation path between the primary base station and the secondary base station, predicts the propagation loss of the propagation path, and outputs an output signal according to the propagation loss. Including that. Predicting propagation loss is to select the first dominant clutter that has the maximum elevation angle from the primary base station to the apex of the clutter from the clutters located between the primary base station and the secondary base station. This includes selecting the second dominant clutter that has the maximum elevation angle when the apex of the clutter is seen from the secondary base station from the clutters arranged between the primary base station and the secondary base station. Predicting propagation loss also means the distance from the primary base station to the first dominant clutter, the distance from the first dominant clutter to the second dominant clutter, and the distance from the second dominant clutter to the secondary base station. Due to the first dominant clutter and the second dominant clutter of the propagation loss, based on the distance of the primary base station, the first dominant clutter, the second dominant clutter, and the respective altitudes of the secondary base stations. Includes calculating the component as a clutter loss. Predicting the propagation loss further includes approximating the components of the propagation loss excluding the clutter loss to the free space loss.

According to one embodiment, the recording medium in which the propagation prediction program is stored is a recording medium in which the program for realizing a predetermined function in the computer is stored. A predetermined function includes estimating the propagation path between the primary base station and the secondary base station, predicting the propagation loss of the propagation path, and outputting an output signal according to the propagation loss. Predicting propagation loss is to select the first dominant clutter that has the maximum elevation angle from the primary base station to the apex of the clutter from the clutters located between the primary base station and the secondary base station. This includes selecting the second dominant clutter that has the maximum elevation angle when the apex of the clutter is seen from the secondary base station from the clutters arranged between the primary base station and the secondary base station. Predicting propagation loss also means the distance from the primary base station to the first dominant clutter, the distance from the first dominant clutter to the second dominant clutter, and the distance from the second dominant clutter to the secondary base station. The component of the propagation loss due to the 1st dominant clutter and the 2nd dominant clutter based on the distance of the primary base station, the 1st dominant clutter, the 2nd dominant clutter and the secondary base station respectively. Includes calculating as a clutter loss. Predicting the propagation loss further includes approximating the components of the propagation loss excluding the clutter loss to the free space loss.

According to the above-described embodiment, it is possible to accurately predict the propagation loss.

FIG. 1 is a diagram showing a configuration example of a propagation prediction system according to an embodiment. FIG. 2A is a block circuit diagram showing a configuration example of a server of a propagation prediction system according to an embodiment. 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. FIG. 3 is a flowchart showing a configuration example of a propagation prediction method according to an embodiment. FIG. 4 is a diagram for explaining a method of selecting a dominant clutter in one embodiment. FIG. 5 is a diagram for explaining parameters derived from the positional relationship between the antenna and the dominant clutter according to the embodiment. FIG. 6 is a diagram for explaining a case where the dominant clutter corresponding to the two antennas is the same in one embodiment. FIG. 7 is a flowchart showing a modified example of the propagation prediction method according to the embodiment. FIG. 8A is a flowchart showing another modification of the propagation prediction method according to the embodiment. FIG. 8B is a flowchart showing still another modification of the propagation prediction method according to the embodiment. FIG. 8C is a flowchart showing a modified example of the propagation prediction method according to the embodiment. FIG. 9 is a diagram for explaining parameters derived from the positional relationship between two antennas having different altitudes and a dominant clutter in one embodiment.

With reference to the attached drawings, a mode for implementing a recording medium containing a propagation prediction system, a propagation prediction method, and a propagation prediction program according to the present invention will be described below.

(First Embodiment)
A configuration example of the propagation prediction system 1 according to the embodiment will be described with reference to FIG. 1. The propagation prediction system 1 is connected to the primary radio communication system 4 and the secondary radio communication system 5. Hereinafter, the 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 in the present embodiment, the primary wireless communication system 4 and the secondary wireless communication system 5 are propagation prediction systems. It does not necessarily exclude the case included in 1.

In the present embodiment, a case where the primary wireless communication system 4 is a transmission / reception system of an FPU (Field Pickup Unit: wireless relay transmission device) will be described. The FPU is used, for example, for material transmission for relaying and 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 assigned to the primary wireless communication system 4.

Further, in the present 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 and smartphones. The secondary wireless communication system 5 includes a

secondary base station

51A, 51B, 51C, 51D, 51E, a secondary operation server 50 that controls the

secondary base stations

51A, 51B, 51C, 51D, 51E, and a secondary mobile station (not shown). Hereinafter, when the

secondary base stations

51A, 51B, 51C, 51D, and 51E are not distinguished, they may be simply referred to as the secondary base station 51. In the example of FIG. 1, the total number of secondary base stations 51 is 5, but the present embodiment is not limited to this total number. Further, the present embodiment is not limited to the total number of secondary mobile stations. The secondary base station 51 and the secondary mobile station perform wireless communication using a predetermined frequency band assigned to the secondary wireless communication system 5.

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

The propagation prediction system 1 controls the suppression of interference from the secondary wireless communication system 5 to the primary wireless communication system 4 by predicting the propagation loss between the primary wireless communication system 4 and the secondary wireless communication system 5. Therefore, first, the propagation prediction system 1 acquires operational information from each of the primary wireless communication system 4 and the secondary wireless communication system 5. The 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). The secondary operation information 54 of the secondary wireless communication system 5 is provided to the propagation prediction system 1 from the secondary operation server 50 included in the secondary wireless communication system 5.

The propagation prediction system 1 predicts the propagation loss of each secondary base station 51 based on these operational information, and makes the interference power from the secondary base station 51 to the primary base station 41 equal to or less than a desired threshold value. Control is performed to limit the operation of the wireless communication system 5. This threshold may be determined based on the protection norms for protecting the primary radio communication system 4. Further, in this control, the propagation prediction system 1 generates and outputs an output signal 14 according to the propagation loss of each secondary base station 51, and the secondary operation server 50 stops each of the secondary base stations 51 based on the output signal 14. Alternatively, it may be performed by operating it.

The propagation prediction system 1 calculates the propagation loss between the primary wireless communication system 4 and the secondary wireless communication system 5 in order to calculate this interference power. In order to calculate this propagation loss, the propagation prediction system 1 refers to the three-dimensional map information of the area where the primary wireless communication system 4 and the secondary wireless communication system 5 are arranged.

The three-dimensional map information includes position information indicating the horizontal position and altitude of the clutter arranged between the primary wireless communication system 4 and the secondary wireless communication system 5. Clutter is a general term for objects other than topography that exist on the surface of the earth, and refers to, for example, buildings and vegetation. The position information of the clutter may represent the horizontal position and altitude of the apex where the diffraction of the electromagnetic wave can occur in the clutter.

Further, the three-dimensional map information includes the position information indicating the horizontal position and altitude of the primary wireless communication system 4, particularly the primary base station 41, and the horizontal position of the secondary wireless communication system 5, particularly the secondary base station 51. It also includes location information that represents altitude. The position information of the primary base station 41 may represent the horizontal position and altitude of the antenna included in the primary base station 41. Further, the position information of the secondary base station 51 may represent the horizontal position and altitude of the antenna included in the secondary base station 51.

The propagation prediction system 1 may hold the three-dimensional map information of the area where the primary wireless communication system 4, the secondary wireless communication system 5 and the clutter are arranged in advance, or acquire it from the outside as needed. May be good.

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

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

With reference to the block circuit diagram of FIG. 2B, one 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. Each of the communication unit 201 and the control unit 204 is a functional unit realized by the input / output device 22, the arithmetic unit 23, and the storage device 24 in cooperation with each other. Each of the clutter selection unit 202 and the propagation loss calculation unit 203 is a functional unit realized by the arithmetic unit 23 and the storage device 24 in cooperation with each other. 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.

With reference to the flowchart of FIG. 3, a configuration example of a propagation prediction method according to an embodiment will be described. It should be noted that explaining one configuration example of the propagation prediction method according to the present embodiment is to explain the operation of the propagation prediction system 1 according to the present embodiment, and is stored in the recording medium according to the present embodiment. It is also to explain a configuration example of the propagation prediction program.

When the propagation prediction method according to the present embodiment is started, step S01 is executed, and the three-dimensional map information is prepared in the storage device 24. As described above, the three-dimensional map information includes 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 the clutter of the primary base station 41 and the secondary base station 51. It belongs to the area where it is 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.

Step S02 is executed after step S01, and the communication unit 201 of the server 2 acquires the primary operation information 44 from the primary base station 41 or the primary operation server, and acquires the secondary operation information 54 from the secondary operation server 50. The primary operation information 44 includes the horizontal position and altitude of the primary base station 41, the frequency band used by the primary radio communication system 4, the strength of the radio signal transmitted from the primary mobile station 42 and reaching the primary base station 41, and the primary radio communication system. Various information indicating the time zone in which 4 operates may be included. Similarly, the secondary operation information 54 includes 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 radio signal transmitted from the secondary base station 51, and the secondary base station 51, respectively. It may contain various information indicating the time zone during which the device is operated. 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. However, it may be supplied in duplicate from a plurality of units. With respect to the operation information supplied in duplicate, which operation information the server 2 adopts may be appropriately determined based on criteria such as, for example, the latest operation information being adopted.

Step S03 is executed after step S02, and the clutter selection unit 202 of the server 2 is placed between the primary base station 41 and the secondary base station 51 from among the clutters arranged between the primary base station 41 and the secondary base station 51. Election a dominant clutter whose effect on propagation loss is dominant.

With reference to FIG. 4, an example of a method of selecting a dominant clutter in one embodiment will be described. In the example of FIG. 4, three clutters 63, 64, and 65 are present between the first antenna 61 of the primary base station 41 and the second antenna 62 of the secondary base station 51. In the following description using the example of FIG. 4, it is assumed that the altitudes of the first antenna 61 and the second antenna 62 are the same, but the present embodiment is not limited to this example.

Each of the clutters 63, 64, and 65 is arranged so as to have a portion that blocks a virtual 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 arranged between the first antenna 61 and the second antenna 62, and the altitude thereof is higher than the altitudes of the first antenna 61 and the second antenna 62. Have. At the very least, no direct wave can propagate between the first antenna 61 and the second antenna 62 along this virtual straight path 612.

On the other hand, the electromagnetic wave emitted from the first antenna 61 can reach the second antenna 62 by diffracting at the ends of the clutters 63, 64, and 65. Similarly, the electromagnetic wave radiated from the second antenna 62 can reach the first antenna 61 by diffracting at the ends of the clutters 63, 64, 65. However, diffraction causes propagation loss.

In the clutter model according to the present embodiment, the clutters 63, 64, and 65 have vertices 631, 641, and 651, respectively. The propagation loss may be calculated in consideration of all the diffractions generated at these vertices 631, 641, and 651, but the amount of calculation for that purpose can be relatively enormous. Therefore, in the present embodiment, among the clutters arranged between the first antenna 61 and the second antenna 62, the first dominant clutter, in which the influence of the propagation loss on the first antenna 61 is dominant, and the first. The approximation is made by selecting the second dominant clutter in which the influence of the propagation loss on the two antennas 62 is dominant, and ignoring the propagation loss caused by the remaining clutter.

In the example of FIG. 4, the clutter 64 is selected as the first dominant clutter corresponding to the first antenna 61. The criterion for selection is that the clutter has the maximum elevation angle when the vertices 631, 641 and 651 of the clutter 63, 64 and 65 are viewed from the first antenna 61. Here, the path 613 which is a straight line connecting the first antenna 61 and the apex 631 of the clutter 63 is blocked by the clutter 64, and the path 615 which is a straight line connecting the first antenna 61 and the apex 651 of the clutter 65 is also blocked by the clutter 64. It is blocked. On the other hand, the path 614, which is a straight line connecting the first antenna 61 and the apex 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.

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

As another criterion for selecting the dominant clutter corresponding to an antenna, the clutter having the maximum clearance coefficient of the clutter with respect to the antenna may be used as the dominant clutter. Here, the clearance coefficient is a parameter related to the loss that the electromagnetic wave propagates through the obstacle.

In the present embodiment, the propagation loss of the propagation path between the first antenna 61 and the second antenna 62, that is, the propagation loss of the propagation path between the primary base station 41 and the secondary base station 51, is the first. The components excluding the clutter loss due to the 1 dominant clutter 64 and the 2nd dominant clutter 65 are calculated and / or predicted by approximating the free space loss. In the example of FIG. 4, when calculating the propagation loss when the electromagnetic wave transmitted from the second antenna 62 is received by the first antenna 61 through the path 625, the path 645 and the path 614, first, the path 625 and the path The propagation loss at 645 and path 614 is approximated to the propagation loss in free space at the distance of path 612. That is, it is estimated that the propagation path between the first antenna 61 and the second antenna 62 is a free space at a distance of the path 612. Next, by adding the clutter loss due to the first dominant clutter 64 and the clutter loss due to the second dominant clutter 65 to the free space loss at the distance of the path 612, the propagation loss is approximated. calculate. Further, as a modification of the method of calculating the propagation loss through the path 625, the path 645, and the path 614, it is assumed that the propagation loss in each of the path 625, the path 645, and the path 614 is the propagation loss in the free space of the same distance. May be good. In this modification, the first antenna 61 and the second antenna 62 are arranged 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 them is a set of

paths

625, 645 and 614 that pass through the apex 641 of the first dominant clutter 64 and the apex 651 of the second dominant clutter 65.

As described above, in the present embodiment, Non-Patent Document 1 (ITU-R (Radiocommunication Sector of International Telecommunication Union), "Recommunication ITU-R P.2108-0 (06/2017) Radiocommunication , [Online], June 20, 2017, Internet <URL: https://www.itu.int/dms_pubrec/itu-r/rec/p/R-REC-P.2108-0-201706-I !! The clutter model defined in PDF-E.pdf>) has been improved. By doing so, in the present embodiment, the propagation loss can be accurately calculated and / or predicted.

When a plurality of secondary base stations 51 exist, the clutter selection unit 202 selects a plurality of second dominant clutters corresponding to the plurality of secondary base stations 51, respectively.

In either case, the clutter selection unit 202 stores information representing the selected dominant clutter in the storage device 24.

With reference to the flowchart of FIG. 3 again, step S04 is executed after step S03, and the propagation loss calculation unit 203 of the server 2 interferes with the primary base station 41 in the frequency band used by the secondary base station 51. Calculate the propagation loss at frequencies included in the frequency band where can occur. Of the propagation losses between the primary base station 41 and the secondary base station 51, the first clutter loss, which is a component caused by the first dominant clutter, is the distance from the primary base station 41 to the first dominant clutter and the primary. It can be calculated based on the respective altitudes of the base station 41 and the first dominant clutter. Similarly, of the propagation loss between the primary base station 41 and the secondary base station 51, the second clutter loss, which is a component caused by the second dominant clutter, is the distance from the secondary base station 51 to the second dominant clutter. And the altitude of each of the secondary base station 51 and the second dominant clutter.

First, clutter loss A _h is the standard model of non-patent document 1 is defined by the following (1a) formula and (1b) Formula (suburban, urban, trees, forests, dense urban) and has units of dB (Decibel).

In the equation (1a), "J (ν)" is a parameter related to the loss due to diffraction, and its unit is dB. “Ν” is the clearance coefficient of the dominant clutter, and its unit is dimensionless. "6.03" is an approximated constant, and depending on the approximated condition, for example, "6.02", "6.04", "any numerical value from 6.00 to 6.06", etc. , Can be changed to another value. "H" is the altitude of the antenna, and its unit is m (meter). "R" is the altitude of the dominant clutter 64 corresponding to this antenna, the unit of which is m.

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

Equation (1a) is applied 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. Further, the equation (1b) is applied when the condition of "h ≧ R" is satisfied, that is, when the electromagnetic wave can be directly propagated along this virtual straight line between the first antenna 61 and the second antenna 62. Will be done. Hereinafter, the calculation method of the equation (1a) will be described.

The parameter J (ν) used in the equation (1a) is defined as the following equation (2).

The clearance coefficient ν used in the equation (2) is defined as the following equation (3).

In equation (3), "K _nu " is a parameter related to frequency. As shown in FIG. 5, “h _dif ” is the difference between the altitude R of the dominant clutter 64 and the altitude h of the first antenna 61, and the unit thereof is m. As shown in FIG. 5, “θ _cult ” is an elevation angle when the apex 641 of the dominant clutter 64 is viewed from the first antenna 61, and the unit thereof is deg (degrees). Here, the value of the elevation angle when looking above the horizontal direction is positive, but the depression angle when looking below the horizontal direction may be treated as an elevation angle having a negative value.

_{The frequency parameter K nu} used in the equation (3) is defined as the following equation (4).

In equation (4), "f" is a frequency, and its unit is GHz (gigahertz).

_{The altitude difference h def} used in the equation (3) is defined as the following equation (5).

_{The elevation angle θ clut} used in the equation (3) is defined as the following equation (6).

In (6), "w _s", as shown in FIG. 5, a horizontal distance to the vertex 641 of the dominant clutter 64 from the first antenna 61, the unit is m. The distance w _s may correspond to a parameter defined as a road width in the standard model of Non-Patent Document 1.

As described above, the dominant in this frequency band is based on the position and altitude information of each of the first antenna 61 and the dominant clutter 64 and the value of the frequency contained in the frequency band used. The clutter loss due to the clutter 64 can be calculated. The clutter loss can be similarly calculated for the dominant clutter corresponding to the second antenna 62.

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 modification in which this propagation path is divided by the dominant clutter 64 and the second dominant clutter 65, the propagation path from the primary base station 41 to the first dominant clutter 64 and the first dominant clutter 64 to the first. The propagation path to the two dominant clutter 65 and the propagation path from the second dominant clutter 65 to the secondary base station 51 are approximated to free space, respectively. The propagation loss, that is, the free space loss in each of these free spaces is defined by the following equation (7).

In equation (7), "L ₀ " is a free space loss, the unit of which is dimensionless, but the propagation loss of the unit is dB by calculating 10 times its log (logarithm with a base of 10). Can be calculated. “D” is the distance at which the electromagnetic wave propagates in the propagation path as a free space, and its unit is m. “Λ” is a wavelength corresponding to the frequency used, and its unit is m.

Next, by adding the clutter losses of the dominant clutters 64 and 65, respectively, to the free space loss L ₀ of each propagation path, the overall propagation loss from the primary base station 41 to the secondary base station 51 is predicted. be able to.

Step S05 is executed after 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 the output signal 14 to the secondary operation server 50. Here, when the propagation loss is smaller than a predetermined threshold value, the propagation loss threshold value may be set so that the interference power from the secondary base station 51 to the primary base station 41 exceeds another predetermined threshold value. The interference power can be calculated from the power and propagation loss of the radio signal transmitted from the secondary base station 51.

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 in which the 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 in which the interference power to the primary base station 41 exceeds a predetermined protection standard in response to the output signal 14.

When step S05 is completed, the flowchart of FIG. 3 ends.

With reference to FIG. 6, another example of the method of selecting the dominant clutter in one embodiment will be described. The example of FIG. 6 is the example of FIG. 4 with the following changes added. That is, the altitude of the clutter 65 is lowered. As a result, the second dominant clutter corresponding to the second antenna 62 was the clutter 65 in the example of FIG. 4, but the clutter 64 in the example of FIG. On the other hand, the first dominant clutter corresponding to the first antenna 61 is the clutter 64 in FIG. 6 as in the case of FIG. That is, in the example of FIG. 6, the first dominant clutter and the second dominant clutter are the same clutter 64.

The calculation of the propagation loss of the dominant clutter in step S04 of the flowchart of FIG. 3 is performed when the first dominant clutter 64 and the second dominant clutter 65 are different clutters as illustrated in FIG. The first dominant clutter 64 and the second dominant clutter 64 may be the same dominant clutter 64 as illustrated in the above, and may be performed by different methods. An example of such a modification will be described with reference to the flowchart of FIG.

When the flowchart of FIG. 7 starts, step S11 is executed, and the propagation loss calculation unit 203 determines whether the first dominant clutter and the second dominant clutter are the same clutter. In order to make this determination, the propagation loss calculation unit 203 may read out the result of selecting the dominant clutter stored in the storage device 24 by the clutter selection unit 202.

In step S11, as illustrated in FIG. 4, when it is determined that the first dominant clutter 64 and the second dominant clutter 65 are different clutters (No), step S12 is executed after step S11. .. In step S12, the propagation loss calculation unit 203 calculates the overall propagation 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.

That is, as described above, the first clutter loss and the second clutter loss due to the diffraction generated in the first dominant clutter 64 and the second dominant clutter 65 are each used by equations (1a) to (7). To calculate.

When step S12 is completed, the flowchart of FIG. 7 ends, and the process proceeds to step S05 of the flowchart of FIG.

In step S11 of the flowchart of FIG. 7, as illustrated in FIG. 6, when it is determined that the first dominant clutter 64 and the second dominant clutter 64 are the same dominant clutter 64 (Yes), step S11. Then step S13 is executed. In step S13, the propagation loss calculation unit 203 calculates the overall propagation 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.

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

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 approximated to free space, respectively. The free space loss in each of these free spaces is defined as the above-mentioned equation (7).

Next, by adding the clutter loss of the first dominant clutter 64 to the free space loss L ₀ of each propagation path, it is possible to predict the overall propagation loss from the primary base station 41 to the secondary base station 51. can.

When step S13 is completed, the flowchart of FIG. 7 ends, and the process proceeds to step S05 of the flowchart of FIG.

As described above, when the dominant clutter corresponding to the first antenna 61 and the second antenna 62 is the same clutter depending on whether or not the flowchart of FIG. 7 is processed, the clutter caused by this dominant clutter. It is possible to select whether the loss is added once or twice in the overall propagation loss between the first antenna 61 and the second antenna 62. This selection may be made depending on the shape of the apex of the dominant clutter and the like. As an example, if 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, FIG. 7 shows. If the flow chart is not processed, the accuracy of predicting the propagation loss may be higher. On the contrary, if the distance between the apex facing the first antenna 61 and the apex facing the second antenna 62 is sufficiently short, the flow chart processing of FIG. 7 is more accurate in predicting the propagation loss. May be higher.

With reference to the flowchart of FIG. 8A, another modification of the propagation prediction method according to one embodiment will be described. In this modification, when calculating the clutter loss due to 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 determined when a predetermined condition is satisfied. To another lower altitude. By doing so, it is possible to simulate propagation by diffraction in the aspect of the dominant clutter, which is not considered in the standard model of Non-Patent Document 1.

When the flowchart of FIG. 8A starts, step S21 is executed, and the propagation loss calculation unit 203 determines whether or not the altitude of the dominant clutter is equal to or higher than the threshold value. In order to make this determination, 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. Further, the propagation loss calculation unit 203 may read out the altitude of the dominant clutter stored in the database or the storage device 24 (not shown).

As a result of the determination in step S21, if the altitude of the dominant clutter selected in step S03 is equal to or higher than a predetermined threshold value (Yes), step S22 is executed after step S21. In step S22, the propagation loss calculation unit 203 replaces the altitude of this dominant clutter with this threshold value. When step S22 is completed, the flowchart of FIG. 8A ends, processing returns to step S04 of the flowchart of FIG. 3 or step S12 or step S13 of the flowchart of FIG. 7, and the propagation loss calculation unit 203 dominates the replaced altitude. The clutter loss and propagation loss are calculated using the clutter altitude.

As a result of the determination in step S21, if the altitude of the dominant clutter selected in step S03 is less than a predetermined threshold value (No), the flowchart of FIG. 8A ends, and the process is performed in step S04 or the flowchart of FIG. Returning to step S12 or step S13 of the flowchart of 7, the propagation loss calculation unit 203 calculates the clutter loss and the propagation loss by using the altitude that has not been replaced as the altitude of the dominant clutter.

Thus, when performing the process shown in the flowchart of FIG. 8A, by using an appropriate altitude threshold as the threshold of the altitude of the dominant clutter, in addition to propagation through diffraction at the apex of the dominant clutter, non-progression is performed. It is possible to simulate the propagation by diffraction in the aspect of the dominant clutter, which is not considered in the standard model of Patent Document 1. This process requires a relatively small amount of calculation as a method for calculating the propagation loss due to diffraction on the side surface of the dominant clutter, and further leads to accurate prediction of the propagation loss.

Further, another modification of the propagation prediction method according to the embodiment will be described with reference to the flowchart of FIG. 8B. Also in this modification, as in the case of FIG. 8A, when calculating the clutter loss due to the dominant clutter in step S04 of the flowchart of FIG. 3 or step S12 or step S13 of the flowchart of FIG. 7, a predetermined condition is satisfied. If so, replace the altitude of the dominant clutter with another lower altitude. By doing so, it is possible to simulate propagation by diffraction in the aspect of the dominant clutter, which is not considered in the standard model of Non-Patent Document 1.

When the flowchart of FIG. 8B starts, step S31 is executed, and the propagation loss calculation unit 203 determines whether or not the altitude difference between the dominant clutter and the corresponding base station is equal to or greater than the threshold value. In order to make this determination, 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. Further, the propagation loss calculation unit 203 may read out the 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.

As a result of the determination in step S31, if 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 value (Yes), step S32 is executed after step S31. In step S32, the propagation loss calculation unit 203 replaces the altitude of the dominant clutter with a value at which the altitude difference is equal to the threshold value. When step S32 is completed, the flowchart of FIG. 8B ends, processing returns to step S04 of the flowchart of FIG. 3 or step S12 or step S13 of the flowchart of FIG. 7, and the propagation loss calculation unit 203 dominates the replaced altitude. The clutter loss and propagation loss are calculated using the clutter altitude.

As a result of the determination in step S31, when the altitude of the dominant clutter selected in step S03 is less than a predetermined threshold value (No), the flowchart of FIG. 8B ends, and the process is performed in step S04 or the flowchart of FIG. Returning to step S12 or step S13 of the flowchart of 7, the propagation loss calculation unit 203 calculates the clutter loss and the propagation loss by using the altitude that has not been replaced as the altitude of the dominant clutter.

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

In the modification described with reference to FIGS. 8A and 8B, when the clutter loss is calculated by replacing the altitude of the dominant clutter with another lower altitude, the dominant clutter is selected as a preliminary step. Sometimes the same replacement is done. This will be described with reference to FIG. 8C.

In this modification, when step S03 of 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 the map information, lists the information of the clutter existing between the primary base station 41 and the secondary base station 51, and initializes the order of processing the clutter. The order in which the clutter is processed may be, for example, the order closest to the primary base station. Also, the argument representing the order is initialized to zero, and the argument representing the total number of clutters listed is stored.

In step S42, the clutter selection unit 202 reads the next clutter information from the clutter information listed. At this time, the argument indicating the order of processing the clutter is incremented. In step S43, it is determined whether or not the value obtained by subtracting the reference altitude from the altitude of the clutter from which the information is read is larger than a predetermined threshold value. Here, the reference altitude is equal to this altitude when 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.

When the first antenna 61 and the second antenna 62 have different altitudes, the altitude of the point closest to the apex of the clutter included in the virtual straight line connecting the first antenna 61 and the second antenna 62. Is. 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 virtual straight line. When calculating the clutter loss derived from the dominant clutter when the first antenna 61 and the second antenna 62 have different altitudes, the altitude of the clutter is similarly replaced. The details will be described later as another embodiment.

In either case, as a result of the determination, if the value obtained by subtracting the reference altitude from the altitude of the clutter from which the information is read is larger than the predetermined threshold value (Yes), the altitude of the clutter is set to another lower altitude in step S44. After the replacement, the process proceeds to step S45. On the contrary, when the value obtained by subtracting the reference altitude from the altitude of the clutter from which the information is read is not larger than the predetermined threshold value (No), the process proceeds to step S45 without executing step S44.

In step S45, it is determined whether or not all the clutter information has been read. In other words, it is determined whether the argument indicating the order in which the clutters are processed has reached the argument indicating the total number of clutters listed. As a result of the determination, if all the clutter information has been read (Yes), the process proceeds to step S46. On the contrary, when the clutter for which the information has not been read remains (No), the process returns to step S42.

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

In this modification, by performing the above processing, both the processing for extracting the dominant clutter and the processing for calculating the clutter loss derived from the dominant clutter are performed by similarly replacing the altitude of the clutter. Consistency can be achieved between processes.

(Second embodiment)
In the first embodiment described above, as illustrated in FIGS. 4 and 6, a case where the altitudes of the first antenna 61 and the second antenna 62 are the same has been described. This configuration conforms to the standard model of Non-Patent Document 1. In the second embodiment, a method of predicting the propagation loss in consideration of the altitude difference between the first antenna 61 and the second antenna 62 will be described.

With reference to FIG. 9, parameters derived from the positional relationship between the two antennas 61 and 62 at different altitudes and the dominant clutter 66 in one embodiment will be described. In the example of FIG. 9, the altitude h _eb of the first antenna 61 is higher than the high R _e of the clutter 66 influence the propagation loss is dominant for the first antenna 61, high R _e of the dominant clutter 66 second 2 Higher than the altitude h _{et of the antenna 62.} Here, each of these advanced _{_{_{h eb, h et, R e}}} , a highly referenced to the same horizontal plane. As in the case of FIG. 5, this standard may be above sea level or at a height above the ground surface, but the present embodiment is not limited to these examples.

If the altitude _{h et} altitude _{h eb} and second antenna 62 of the first antenna 61 are different, a virtual straight line connecting the first antenna 61 and the second antenna 62 is not horizontal. Moreover, even highly R _e dominant clutter 66 is lower than the height h _eb of the first antenna 61, depending on the position of the dominant clutter 66, as illustrated in FIG. 9, the path 612 of the virtual straight line It may block. Even in this case, the electromagnetic wave radiated from the second antenna 62 via the path 616 connecting the first antenna 61 and the apex 661 of the dominant clutter and the path 626 connecting the apex 661 and the second antenna 62 is the first antenna. 61 can be reached. _{In the present embodiment, the altitude heb} _{of the first antenna 61 and the altitude h et} of the second antenna 62 are different by correcting the equation used for calculating the propagation loss in the first embodiment as follows. Even in this case, it is possible to calculate the propagation loss.

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

In equation (8), "K _nu " is a parameter related to the frequency defined in equation (4). The “ _h'dif ” is the length obtained by correcting _{the altitude difference h div} of the above-mentioned equation (5). The "_θ'clut" is an angle corrected by _{the elevation angle θ clut} of the above-mentioned equation (6).

_{As shown in FIG. 9, the length h'dim} of the equation (8) is the length in the vertical direction from the apex 661 of the dominant clutter 66 to the virtual straight line connecting the first antenna 61 and the second antenna 62. And the unit is m. The definition of the length _h'dim _{is a correction of the definition of h def according to} the equation (5) used in the first embodiment as shown in the following equation (9).

In (9), "R _e" is highly dominant clutter 66, the unit is m. “H _et ” is the altitude of the second antenna 62, and its unit is m. “H _eb ” is the altitude of the first antenna 61, and its unit is m. "W _s" is the distance in the horizontal direction to the dominant clutter 66 from the first antenna 61, the unit is m. “D” is the horizontal distance from the first antenna 61 to the second antenna 62, and the unit thereof is m. “Theta _tr ” is the angle between the horizontal direction and the path 612 of a virtual straight line connecting the first antenna 61 and the second antenna 62, and the unit is deg (degrees).

_{The angle θ tr} of the equation (9) is defined as the following equation (10).

_{As shown in FIG. 9, the angle θ'clut in the} equation (8) is a virtual straight line path 612 connecting the first antenna 61 and the second antenna 62, and the apex 661 of the first antenna 61 and the dominant clutter 66. It is an angle between the path 616 of a virtual straight line connecting the two, and its unit is deg (degree). The definition of the angle _θ'clut _{is a correction of the definition of the elevation angle θ clut according to} the equation (6) used in the first embodiment as shown in the following equation (11).

Here, the angle _θ'clut is an elevation angle obtained from the first antenna 61 as seen from the apex 661 of the dominant clutter 66 when the path 612 of a virtual straight line connecting the first antenna 61 and the second antenna 62 is used as a reference. Can be regarded as.

As a result of the above correction, the application conditions of the formula (1) are also corrected as the following formulas (12a) and (12b).

By correcting each definition as described above, according to the present embodiment, even between the primary base station 41 and the secondary base station 51 having different altitudes of the antennas 61 and 62, the case of the first embodiment Similarly, the propagation loss can be calculated accurately.

(Third embodiment)
In this embodiment, the following changes are made as modified examples of the first embodiment and the second embodiment. That is, in the propagation loss between the primary base station 41 and the secondary base station 51, the first clutter loss which is a component caused by the first dominant clutter and the second clutter loss which is a component caused by the second dominant clutter. When and is included, the propagation loss is calculated by considering only one of the first clutter loss and the second clutter loss. At this time, of the first clutter loss and the second clutter loss, the other one not considered in the calculation of the propagation loss is replaced with the free space loss when calculating the propagation loss. The definition of free space loss is as in Eq. (7) above.

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

In the modification of the present embodiment, on the contrary, the propagation loss is calculated by considering the larger loss of the first clutter loss and the second clutter loss and replacing the smaller loss with the free space loss. do.

In the present embodiment, by calculating as described above, the prediction of propagation loss can be accurately predicted, in particular, when a margin is set for the signal output when the frequency is shared between the primary wireless communication system 4 and the secondary wireless communication system 5. It can be carried out.

Although the invention made by the inventor has been specifically described above based on the embodiment, the present invention is not limited to the above-described embodiment and can be variously modified without departing from the gist thereof. Needless to say. Further, the respective features described in the above-described embodiments can be freely combined within a technically consistent range.

As a modification of each of the above-described embodiments, the clutter loss may be calculated using the three-dimensional map information which is divided into a plurality of areas and the altitude information is registered for each area. For example, mesh-shaped three-dimensional map information divided in a predetermined unit length in the horizontal direction may be used. The altitude information registered in these areas is the representative altitude of each area, and may be, for example, the average altitude in the area. The selection of the dominant clutter and the calculation of the clutter loss due to the dominant clutter may be performed assuming that the clutter of the representative altitude exists at the representative position of each region, for example, at the geometric center position. That is, the region where the elevation angle of the region is maximum when viewed from the antenna is selected as the dominant region, and the distance from the antenna to the representative position of the dominant region, the height of the antenna, and the representative altitude are used. Then, the component due to the dominant region of the propagation loss may be calculated. Further, the area where the primary base station 41 and the secondary base station 51 are arranged is horizontally divided into a plurality of meshes with a predetermined unit length, and the average value of the altitudes of the clutter included in each mesh is calculated as the altitude of each mesh. Can be treated as. In this case, in step S03 of the flowchart of FIG. 3, the altitude of the clutter arranged between the primary base station 41 and the secondary base station 51 is set to the altitude of the mesh arranged between the primary base station 41 and the secondary base station 51. It can be highly replaced to elect the dominant mesh instead of the dominant clutter. Further, in step S04 of the flowchart of FIG. 3, the altitude of the dominant clutter can be replaced with the altitude of the dominant mesh, and the clutter loss and the propagation loss can be calculated.

As a model of the clutter, a model having a vertex at the uppermost position has been described, but the present disclosure is not limited to this, and it may be a structure formed in a rectangular parallelepiped shape, for example, a building. In this case, the position of the geometric center of the building may be used as the position of the clutter, or the position of the wall surface on the side close to the antenna may be used. Further, a model may be adopted in which the apex of the clutter is directly above the position of the clutter and has the altitude of the clutter.

As a modification of step S05 in the flowchart of FIG. 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 according to the propagation loss displayed on the display device.

This application claims priority based on Japanese Patent Application No. 2020-109410 filed on June 25, 2020 and Japanese Patent Application No. 2020-170283 filed on October 8, 2020. , All of its disclosures are taken here.

Claims

An arithmetic unit that estimates the propagation path between the primary base station and the secondary base station and predicts the propagation loss in the propagation path.
It is equipped with an input / output device that outputs an output signal according to the propagation loss.
The arithmetic unit is
Among the clutters arranged between the primary base station and the secondary base station, the first dominant clutter having the maximum elevation angle when the apex of the clutter is seen from the primary base station and the clutter from the secondary base station. Select the second dominant clutter that has the maximum elevation angle when looking at the apex of
The distance from the primary base station to the first dominant clutter, the distance from the first dominant clutter to the second dominant clutter, and the distance from the second dominant clutter to the secondary base station. The first dominant clutter and the second dominant clutter of the propagation loss are based on the respective altitudes of the primary base station, the first dominant clutter, the second dominant clutter and the secondary base station. Calculate the component caused by the clutter loss as a clutter loss.
A propagation prediction system that predicts the propagation loss by approximating the components of the propagation loss excluding the clutter loss to the free space loss.
In the propagation prediction system according to claim 1,
The input / output device is a propagation prediction system that outputs the output signal for stopping the secondary base station when the propagation loss is lower than a predetermined threshold value.
In the propagation prediction system according to claim 1 or 2.
The arithmetic unit is
The first dominant clutter of the clutter loss based on the first distance from the primary base station to the first dominant clutter and the respective altitudes of the primary base station and the first dominant clutter. Calculate the first clutter loss due to
The second dominant clutter of the clutter loss is based on the second distance from the secondary base station to the second dominant clutter and the respective altitudes of the secondary base station and the second dominant clutter. Propagation prediction system that calculates the second clutter loss due to.
In the propagation prediction system according to claim 3,
A propagation prediction system that predicts the propagation loss by replacing the component having the larger loss among the first clutter loss and the second clutter loss, which are components of the clutter loss, with free space loss.
In the propagation prediction system according to claim 3,
A propagation prediction system that predicts the propagation loss by replacing a component having a smaller loss among the first clutter loss and the second clutter loss, which are components of the clutter loss, with free space loss.
In the propagation prediction system according to claim 1 or 2.
When the first dominant clutter and the second dominant clutter are the same clutter, the arithmetic unit is used.
The shorter of the first distance from the primary base station to the same clutter and the second distance from the secondary base station to the same clutter.
The altitude of the base station in which the distance between the primary base station and the secondary base station to the same clutter is shorter than the distance, and the altitude of the base station.
With the altitude of the same clutter,
A propagation prediction system that calculates the clutter loss based on.
In the propagation prediction system according to any one of claims 1 to 6.
The arithmetic unit is
When the first dominant clutter and the second dominant clutter are elected, the altitude of each of the clutters arranged between the primary base station and the secondary base station is equal to or higher than a predetermined altitude threshold. When the altitude of the clutter was replaced with the altitude threshold value, the first dominant clutter having the maximum elevation angle when the apex of the clutter was seen from the primary base station and the apex of the clutter were seen from the secondary base station. The second dominant clutter with the maximum elevation angle is selected from the clutters, respectively.
When the first altitude of the first dominant clutter is equal to or higher than the altitude threshold value, the first altitude is replaced with the altitude threshold value to calculate the clutter loss.
A propagation prediction system that calculates the clutter loss by replacing the second altitude with the altitude threshold when the second altitude of the second dominant clutter is equal to or higher than the altitude threshold.
In the propagation prediction system according to any one of claims 1 to 6.
The arithmetic unit is
When the first dominant clutter is elected, the altitude difference between the clutter and the primary base station is a predetermined altitude difference threshold value in each of the clutters arranged between the primary base station and the secondary base station. When the above is the case, when the altitude of the clutter is replaced with a value at which the altitude difference is equal to the altitude difference threshold value, the first control that maximizes the elevation angle when the apex of the clutter is viewed from the primary base station. Select the target clutter from the clutter,
When the first altitude difference between the first dominant clutter and the primary base station is equal to or higher than the altitude difference threshold value, the altitude of the first dominant clutter is set to a value at which the first altitude difference becomes equal to the altitude difference threshold value. Replace and calculate the clutter loss,
When the second dominant clutter is elected, the altitude difference between the clutter and the secondary base station is a predetermined altitude difference threshold value in each of the clutters arranged between the primary base station and the secondary base station. When the above is the case, when the altitude of the clutter is replaced with a value at which the altitude difference is equal to the altitude difference threshold value, the second control that maximizes the elevation angle when the apex of the clutter is viewed from the secondary base station. Select the target clutter from the clutter,
When the second altitude difference between the second dominant clutter and the secondary base station is equal to or higher than the altitude difference threshold value, the altitude of the second dominant clutter is set to a value at which the second altitude difference becomes equal to the altitude difference threshold value. A propagation prediction system that replaces and calculates the clutter loss.
In the propagation prediction system according to any one of claims 1 to 6.
The arithmetic unit is
When selecting the first dominant clutter and the second dominant clutter, in each of the clutters arranged between the primary base station and the secondary base station, from the apex of the clutter, the primary base When the vertical length to the virtual straight line connecting the station and the secondary base station is equal to or greater than a predetermined length threshold, and the altitude of the clutter is replaced with an altitude at which the length becomes the length threshold. The first dominant clutter having the maximum elevation angle when the apex of the clutter is seen from the primary base station, and the second dominant clutter having the maximum elevation angle when the apex of the clutter is seen from the secondary base station. Are selected from the above clutters, respectively.
When the first length in the vertical direction from the first vertex of the first dominant clutter to the virtual straight line is equal to or greater than a predetermined length threshold value, the first length becomes the length threshold value. The clutter loss is calculated by substituting the altitude of the first dominant clutter.
When the second length in the vertical direction from the second apex of the second dominant clutter to the virtual straight line is equal to or greater than the length threshold value, the second length becomes the length threshold value. A propagation prediction system that replaces the altitude of the second dominant clutter and calculates the clutter loss.
In the propagation prediction system according to any one of claims 1 to 9,
The arithmetic unit is
The area where the first dominant clutter and the second dominant clutter are arranged is divided into a plurality of areas, and the representative position and the representative altitude of the representative position are registered in each of the plurality of areas with reference to the map information. ,
From the area that blocks the virtual straight line connecting the primary base station and the secondary base station, the first control that maximizes the elevation angle when the virtual apex at the representative altitude of the representative position of the area is seen from the primary base station. The target region is defined as the first dominant clutter, and the second dominant region having the maximum elevation angle when the virtual apex at the representative altitude of the representative position of the region is viewed from the secondary base station is defined as the second dominant clutter. Propagation prediction system to be elected.
In the propagation prediction system according to any one of claims 1 to 9,
The arithmetic unit includes first operational information including information representing the position, altitude, and frequency band of the primary base station, and second operational information including information representing the position, altitude, and frequency band of the secondary base station. A propagation prediction system that predicts the propagation loss based on the above.
Estimating the propagation path between the primary base station and the secondary base station, predicting the propagation loss in the propagation path, and
Including outputting an output signal according to the propagation loss.
Predicting the propagation loss is
From the clutters arranged between the primary base station and the secondary base station, the first dominant clutter having the maximum elevation angle when the apex of the clutter is seen from the primary base station is selected.
From the clutters arranged between the primary base station and the secondary base station, the second dominant clutter having the maximum elevation angle when the apex of the clutter is seen from the secondary base station is selected.
The distance from the primary base station to the first dominant clutter, the distance from the first dominant clutter to the second dominant clutter, and the distance from the second dominant clutter to the secondary base station. The first dominant clutter and the second dominant clutter of the propagation loss are based on the respective altitudes of the primary base station, the first dominant clutter, the second dominant clutter and the secondary base station. To calculate the component caused by the clutter loss,
A propagation prediction method including approximating a component of the propagation loss excluding the clutter loss to a free space loss.
It is a non-temporary and tangible recording medium that stores a propagation prediction program for realizing a predetermined function in a computer.
The predetermined function is
Assuming a propagation path between the primary base station and the secondary base station, predicting the propagation loss in the propagation path, and
Including outputting an output signal according to the propagation loss.
Predicting the propagation loss is
From the clutters arranged between the primary base station and the secondary base station, the first dominant clutter having the maximum elevation angle when the apex of the clutter is seen from the primary base station is selected.
From the clutters arranged between the primary base station and the secondary base station, the second dominant clutter having the maximum elevation angle when the apex of the clutter is seen from the secondary base station is selected.
The distance from the primary base station to the first dominant clutter, the distance from the first dominant clutter to the second dominant clutter, and the distance from the second dominant clutter to the secondary base station. The first dominant clutter and the second dominant clutter of the propagation loss are based on the respective altitudes of the primary base station, the first dominant clutter, the second dominant clutter and the secondary base station. To calculate the component caused by the clutter loss,
A recording medium containing a propagation prediction program including predicting the propagation loss by approximating the components of the propagation loss excluding the clutter loss to the free space loss.