JP7617472B2 - Station location design support device and station location design support method - Google Patents

Description

The present invention relates to a station placement design support device and a station placement design support method.

Many drop cables, which are overhead cables used to pull optical lines from utility poles to individual buildings, have been installed for a long time. Replacing aging drop cables with new ones is expected to require a great deal of labor and cost, so in recent years, the conversion of drop cables to wireless has become widespread. To convert drop cables to wireless, it is necessary to design the locations of the wireless base station devices installed on utility poles and the wireless terminal station devices installed in each building, for example, a station placement design such as the one below is required.

Figure 40 is a schematic diagram with some modifications based on the use case proposed by mmWave Networks in the Telecom Infra Project (TIP) (major members: Facebook, Deutsche Telecom, Intel, NOKIA, etc.), a consortium that promotes open specifications for communication network equipment in general. mmWave Networks is one of the project groups of TIP, and aims to build a network that is faster and cheaper than laying optical fiber by using unlicensed millimeter wave radio.

Terminal station devices (hereinafter referred to as "terminal stations") are installed on the walls of buildings such as buildings 800-801 and houses 810-812 shown in Figure 40. Base station devices (hereinafter referred to as "base stations") are installed on utility poles 821-826 shown in Figure 40. Base stations 830-834 and terminal stations 840-844 shown in Figure 40 are devices called mmWave DNs (Distribution Nodes).

The base stations 830-834 are connected to communication equipment provided in station buildings (Fiber PoP (Point of Presence)) 850-851 by optical fibers 900-901, respectively. These communication equipment are connected to the provider's communication network. Between the terminal stations 840-844 and the base stations 830-834, mmWave Links, i.e., millimeter wave radio, are used. In Figure 40, the millimeter wave radio links are shown by dashed lines.

In a communications network configuration in which base stations 830-834 are installed on utility poles 821-826, terminal stations 840-844 are installed on the walls of buildings, and communication between the two stations is via millimeter wave wireless, the process of selecting candidate locations for installing base stations 830-834 and terminal stations 840-844 is referred to as station placement design.

One method for designing base stations is to use three-dimensional point cloud data obtained by imaging space. In this method, for example, first, a moving object such as a vehicle equipped with an MMS (Mobile Mapping System) is driven along roads surrounding an area to be evaluated such as a residential area to obtain three-dimensional point cloud data. Next, the obtained point cloud data is used to evaluate wireless communication between the base stations 830-834 and the terminal stations 840-844.

The evaluation means include a means for determining the visibility between the two stations in three dimensions and a means for calculating the shielding rate. Here, the "shielding rate" is an index showing the degree to which objects (shielding objects) existing between the base stations 830-834 and the terminal stations 840-844 affect wireless communication, and from the opposite perspective, it can also be called the "transmittance rate." To realize such an evaluation means, it is necessary to have point cloud data for all objects existing in the evaluation area including the candidate installation locations of the base stations 830-834 and the candidate installation locations of the terminal stations 840-844.

JP 2020-107955 A JP 2020-113826 A JP 2020-120161 A

Wataru Yamada, Naoki Kita, Takatoshi Sugiyama, "R&D Hot Corner Solution - A Method to Reduce the Calculation Amount of MIMO Propagation Channel Estimation Using Ray Tracing Method", NTT Technical Journal, Vol. 22, No. 11, pp. 61-64, November 2010, [Retrieved March 24, 2021], Internet (URL: https://www.ntt.co.jp/journal/1011/files/jn201011061.pdf) Tetsuro Imai, "Technology Reports - Ray Tracing Method Using Genetic Algorithm for Estimating Radio Wave Propagation", NTT DoCoMo Technical Journal, Vol. 15, No. 3, pp. 20-26, October 2007, [Retrieved March 24, 2021], Internet (URL: https://www.nttdocomo.co.jp/binary/pdf/corporate/technology/rd/technical_journal/bn/vol15_3/vol15_3_020jp.pdf) Tetsuro Imai, "Invited Paper: Simulation of Mobile Propagation Using Ray Tracing Method", Simulation and Analysis Methods and Antenna and Propagation Technology Special Issue, IEICE Transactions on Electronics, Information and Communication Engineers (IEICE) Transactions on Electronics, Information and Communication Engineers (IEICE), September 2009, [Retrieved March 24, 2021], Internet (URL: https://www.ieice.org/cs/jpn/JB/PDF/2009/j92-b_9_1333.pdf) Masaru Fukushige, Tetsuro Imai, "Analysis of urban polarization characteristics using ray tracing method", 497th URSI-F Subcommittee, pp.1-7, September 9, 2005, [Retrieved March 24, 2021], Internet (URL: https://ursi-f.nict.go.jp/doc/URSI_F_2005Sep09_fukushige.pdf) Yukiko Kishiki, Junichi Takada, "Method of Introducing Complex Scattering Cross Section in Microcell Propagation Simulation Using Ray Tracing Method and Application Results", 522nd URSI-F Meeting Materials, pp.1-5, March 7, 2008, [Retrieved March 24, 2021], Internet (URL: http://www.ap.ide.titech.ac.jp/publications/Archive/URSI-F_0803Kishiki.pdf) Junichi Takada, "Special contribution - Simulation for site-specific radio wave propagation prediction: Limitations of ray tracing method and application of physical optics approximation", Hitachi International Electrical Engineering Review 2019 Edition, No. 20, pp. 1-10, [Retrieved March 24, 2021], Internet (URL: https://www.hitachi-kokusai.co.jp/laboratories/gihou_20/2019_no20_002.pdf)

As described above, when trying to cover an area such as a city with a communication network in which base stations are installed on utility poles and terminal stations are installed on the walls of buildings, wireless communication operators may have to design station placement over a wide area, for example, several hundred meters square, as the evaluation area. In such a case, if the visibility determination process and the calculation process of the shielding rate were to be performed for all combinations of candidate installation positions for base stations (e.g., all utility pole positions) and candidate installation positions for terminal stations (e.g., at least one position on the wall of every building) in the evaluation area, the amount of calculation would be enormous. Therefore, there was a problem in that it was necessary to reduce the number of combinations of candidate installation positions for both stations to be evaluated to a number that could be completed within a realistic calculation time.

In view of the above circumstances, the present invention aims to provide a technology that can appropriately present combinations of candidate locations for installing communication stations while minimizing increases in the amount of calculations.

One aspect of the present invention is a station placement design support device that includes: a generation unit that generates a first combination candidate group, which is a set of combinations of a candidate installation position of a first wireless station and a candidate installation position of a second wireless station that communicates with the first wireless station in an evaluation target area; a first determination unit that determines, for each of the combinations included in the first combination candidate group, whether or not there is line of sight between the candidate installation positions of the first wireless station and the candidate installation positions of the second wireless station based on first environmental information including information indicating the planar positions and heights of objects that may block or reflect radio waves present in the evaluation target area; a second determination unit that determines, for each combination determined by the first determination unit to have line of sight, whether or not there is line of sight between the candidate installation positions of the first wireless station and the candidate installation positions of the second wireless station based on second environmental information that has a larger amount of information than the first environmental information; and an output unit that outputs a second combination candidate group, which is a set of combinations determined by the second determination unit to have line of sight.

One aspect of the present invention is a station placement design support method including: a generation step of generating a first combination candidate group, which is a set of combinations of a candidate installation position of a first wireless station and a candidate installation position of a second wireless station that communicates with the first wireless station in an evaluation target area; a first determination step of determining, for each of the combinations included in the first combination candidate group, whether or not there is line of sight between the candidate installation positions of the first wireless station and the candidate installation positions of the second wireless station based on first environmental information including information indicating the planar positions and heights of objects that may block or reflect radio waves present in the evaluation target area; a second determination step of determining, for each combination determined in the first determination step that there is line of sight between the candidate installation positions of the first wireless station and the candidate installation positions of the second wireless station based on second environmental information having a larger amount of information than the first environmental information; and an output step of outputting a second combination candidate group, which is a set of combinations determined in the second determination step that there is line of sight.

The present invention makes it possible to appropriately present combinations of candidate locations for installing communication stations while minimizing increases in the amount of calculations.

1 is a block diagram showing a functional configuration of a station placement design assistance device 1 according to a first embodiment of the present invention. 4 is a flowchart showing an operation of the station placement design assistance device 1 in the first embodiment of the present invention. 5 is a flowchart showing an example of an operation of a visibility determination process by a map visibility determination unit 16 according to the first embodiment of the present invention. 5 is a flowchart showing an example of an operation of a visibility determination process by a point cloud visibility determination unit 23 according to the first embodiment of the present invention. 4A to 4C are diagrams for explaining the effect of reducing the amount of calculation by the station placement design assisting device 1 in the first embodiment of the present invention. 11A and 11B are diagrams for explaining visibility determination and reflection visibility determination on a horizontal plane by a station placement design assistance device 1 according to a second embodiment of the present invention. 11A and 11B are diagrams for explaining visibility determination and reflection visibility determination on a vertical cross section by a station placement design assistance device 1 according to a second embodiment of the present invention. 13 is a flowchart showing an example of an operation of a visibility determination process by a map visibility determination unit 16 according to the second embodiment of the present invention. FIG. 11 is a diagram for explaining an example of visibility determination by a station placement design assistance device 1 according to a second embodiment of the present invention. FIG. 11 is a diagram for explaining an example of visibility determination by a station placement design assistance device 1 according to a second embodiment of the present invention. FIG. 11 is a diagram for explaining an example of visibility determination by a station placement design assistance device 1 according to a second embodiment of the present invention. FIG. 11 is a diagram for explaining an example of visibility determination by a station placement design assistance device 1 according to a second embodiment of the present invention. FIG. 11 is a diagram for explaining an example of visibility determination by a station placement design assistance device 1 according to a second embodiment of the present invention. FIG. 11 is a diagram for explaining an example of visibility determination by a station placement design assistance device 1 according to a second embodiment of the present invention. FIG. 11 is a diagram for explaining an example of visibility determination by a station placement design assistance device 1 according to a second embodiment of the present invention. FIG. 11 is a diagram for explaining an example of visibility determination by a station placement design assistance device 1 according to a second embodiment of the present invention. FIG. 11 is a diagram for explaining an example of visibility determination by a station placement design assistance device 1 according to a second embodiment of the present invention. FIG. 11 is a diagram for explaining an example of visibility determination by a station placement design assistance device 1 according to a second embodiment of the present invention. FIG. 11 is a diagram for explaining an example of visibility determination by a station placement design assistance device 1 according to a second embodiment of the present invention. FIG. 11 is a diagram for explaining an example of visibility determination by a station placement design assistance device 1 according to a second embodiment of the present invention. FIG. 11 is a diagram for explaining an example of visibility determination by a station placement design assistance device 1 according to a second embodiment of the present invention. FIG. 11 is a diagram for explaining an example of visibility determination by a station placement design assistance device 1 according to a second embodiment of the present invention. FIG. 11 is a diagram for explaining an example of visibility determination by a station placement design assistance device 1 according to a second embodiment of the present invention. FIG. 13 is a diagram for explaining an example of visibility determination by a station placement design assistance device 1 according to a third embodiment of the present invention. FIG. 13 is a diagram for explaining an example of visibility determination by a station placement design assistance device 1 according to a third embodiment of the present invention. FIG. 13 is a diagram for explaining an example of visibility determination by a station placement design assistance device 1 according to a third embodiment of the present invention. 13 is a flowchart showing an example of an operation of a visibility determination process by a map visibility determination unit 16 according to a third embodiment of the present invention. FIG. 13 is a diagram for explaining an example of visibility determination by a station placement design assistance device 1 according to a fourth embodiment of the present invention. FIG. 13 is a diagram for explaining an example of visibility determination by a station placement design assistance device 1 according to a fourth embodiment of the present invention. FIG. 13 is a diagram for explaining an example of visibility determination by a station placement design assistance device 1 according to a fourth embodiment of the present invention. FIG. 31 is a flowchart showing an example of the operation of the visibility determination process by the map visibility determination unit 16 according to the fourth embodiment of the present invention. FIG. 13 is a diagram for explaining an example of visibility determination by a station placement design assistance device 1 according to a fifth embodiment of the present invention. FIG. 13 is a diagram for explaining an example of visibility determination by a station placement design assistance device 1 according to a fifth embodiment of the present invention. FIG. 13 is a diagram for explaining an example of visibility determination by a station placement design assistance device 1 according to a fifth embodiment of the present invention. FIG. 13 is a diagram for explaining an example of visibility determination by a station placement design assistance device 1 according to a fifth embodiment of the present invention. 13 is a flowchart showing an example of an operation of a visibility determination process by a map visibility determination unit 16 according to the fifth embodiment of the present invention. 11 is a diagram for explaining four possible cases as a result of visibility determination. FIG. A figure showing the relationship between the results of visibility judgment on a horizontal plane and the results of visibility judgment on a vertical cross section, and whether or not it is subject to visibility judgment based on point cloud data. A figure showing the relationship between the results of reflection visibility judgment on a horizontal plane and the results of reflection visibility judgment on a vertical cross section, and whether or not it is subject to visibility judgment based on point cloud data. FIG. 1 is a diagram illustrating an example of a use case proposed by TIP.

Below, the station placement design support device and station placement design support method of the embodiment will be explained with reference to the drawings.

First Embodiment
Hereinafter, a description will be given of the station placement design support device 1 in the first embodiment. The station placement design support device 1 in this embodiment is a device for supporting station placement design that determines the installation positions of base stations to be installed on utility poles and the installation positions of terminal stations to be installed in each building.

The station location design support device 1 determines whether communication is possible for each combination of at least one candidate installation location for a base station and at least one candidate installation location for a terminal station. In this embodiment, the station location design support device 1 determines whether communication is possible by determining whether there is line of sight or calculating the shielding rate between the candidate installation location for the base station and the candidate installation location for the terminal station.

The presence or absence of line of sight here refers to whether or not there is an obstruction blocking the propagation of radio waves transmitted and received between the base station and the terminal station when the base station and the terminal station are installed at the candidate installation locations for the base station and the terminal station, respectively. If there is no obstruction blocking the radio waves on the propagation path between the base station and the terminal station, it is said that there is "line of sight," and if there is an obstruction blocking the radio waves on the propagation path between the base station and the terminal station, it is said that there is "no line of sight."

Hereinafter, the judgment of the presence or absence of visibility and the judgment of the possibility of communication by calculating the shielding rate are collectively referred to as "visibility judgment." The station location design support device 1 provides station location design support by presenting a set of appropriate combination candidates (hereinafter referred to as "candidate combination group") for the candidate installation positions of both stations identified by the visibility judgment.

The combination candidate group presented by the station placement design support by the station placement design support device 1 is used in the subsequent station placement design. The station placement design device that performs the station placement design evaluates the communication state for each of the combination candidates included in the combination candidate group presented by the station placement design support device 1, for example by performing a radio wave propagation simulation. The station placement design device determines the installation positions of the base station and the terminal station based on the evaluation results.

The station design support device 1 first narrows down the combination candidates in advance by performing visibility assessment using low-density data that indicates the positions of objects such as obstructions that exist within the evaluation target area. Obstructions here refer to objects that may block the propagation of radio waves transmitted and received between the base station and the terminal station. Obstructions include all objects that may block the propagation of radio waves, such as buildings (architectures) such as dwellings and buildings, structures such as residential walls and elevated roads, structures such as road signs and billboards, plants such as roadside trees and garden trees, and raised ground.

Low-density data (first environmental information) is data with a relatively small amount of information, and in this embodiment, it is three-dimensional map information (hereinafter simply referred to as "map information") in which information showing the (two-dimensional) contours of buildings on a horizontal plane is given with height information of the buildings. The height information in this embodiment is information showing the height of the highest point of each building.

The map information in this embodiment is not a map generated based on point cloud data (hereinafter simply referred to as "point cloud data") obtained by an MMS or the like, but is information based on a general map, such as a residential map produced by a map production company (e.g., by surveying, etc.). Therefore, the map information in this embodiment includes, for example, information indicating the outline and height of a building, but may not include information regarding the position of objects other than buildings (e.g., the above-mentioned structures, works, and plants, etc.). When low-density data is used to determine visibility, the determination accuracy is relatively low, but the amount of calculation required for the determination process is relatively small.

Then, the station design support device 1 performs visibility assessment for each of the candidate combinations narrowed down by the visibility assessment based on the low-density data, using high-density data representing the positions of objects such as obstructions that exist within the evaluation area.

High-density data (second environmental information) is data with a relatively large amount of information, and in this embodiment, it is three-dimensional point cloud data obtained by, for example, an MMS. The point cloud data includes information indicating the three-dimensional positions of all objects that may be obstructions, including not only buildings but also objects other than buildings that are not included in the above map information. Therefore, the point cloud data is data with a much larger amount of information than the above map information. In visibility determination using high-density data, the determination accuracy is relatively high, but the amount of calculation required for the determination process is relatively large.

In this way, the station placement design support device 1 of this embodiment performs visibility assessment in advance using low-density data, thereby eliminating in advance combination candidates for the installation positions of both stations that are unlikely to be able to communicate. The station placement design support device 1 then performs detailed visibility assessment using high-density data for only the narrowed-down combination candidates. This allows the station placement design support device 1 to present a group of appropriate combination candidates for the installation positions of the base station and the terminal station with less calculation effort while suppressing a decrease in assessment accuracy.

[Functional configuration of a station placement design assistance device]
The following describes the functional configuration of the station placement design assistance device 1. Fig. 1 is a block diagram showing the functional configuration of a station placement design assistance device 1 according to a first embodiment of the present invention.

As shown in Fig. 1, the station placement design support device 1 includes an equipment information acquisition unit 11, a base station candidate position extraction unit 12, a map information acquisition unit 13, a terminal station candidate position extraction unit 14, a combination candidate group generation unit 15, a map visibility determination unit 16, a point cloud data acquisition unit 21, a data matching unit 22, a point cloud visibility determination unit 23, a memory unit 30, and a combination candidate group output unit 40. The station placement design support device 1 is an information processing device such as a general-purpose computer.

The equipment information acquisition unit 11 acquires equipment information, for example, from an external device. The equipment information here includes information indicating the planar position and height of outdoor equipment, such as utility poles on which base stations can be installed. The equipment information acquisition unit 11 outputs the acquired equipment information to the base station candidate position extraction unit 12.

Note that "planar position" here refers to two-dimensional coordinates that do not include height (vertical) coordinates. In the following explanation, unless otherwise specified, "position" refers to three-dimensional coordinates that include height (vertical) coordinates.

The equipment information acquisition unit 11 may acquire the equipment information from an external storage device, or from an external device via a communication network. Alternatively, the equipment information may be pre-stored in the storage unit 30, and the equipment information acquisition unit 11 may acquire the equipment information from the storage unit 30.

The base station candidate position extraction unit 12 acquires the equipment information output from the equipment information acquisition unit 11. The base station candidate position extraction unit 12 extracts candidate installation positions for the base station based on the acquired equipment information. The base station candidate position extraction unit 12 outputs information indicating the extracted candidate installation positions for the base station and the equipment information to the combination candidate group generation unit 15.

The map information acquisition unit 13 acquires map information, for example, from an external device. The map information here includes information indicating the planar position and height of the contours of buildings, such as houses and buildings. The map information acquisition unit 13 outputs the acquired map information to the terminal station candidate position extraction unit 14 and the data matching unit 22.

The map information acquisition unit 13 may acquire the map information from an external storage device, or from an external device via a communication network. Alternatively, the map information may be pre-stored in the storage unit 30, and the map information acquisition unit 13 may acquire the map information from the storage unit 30.

The terminal station candidate position extraction unit 14 acquires the map information output from the map information acquisition unit 13. The terminal station candidate position extraction unit 14 extracts candidate installation positions for the terminal station based on the acquired map information. The terminal station candidate position extraction unit 14 outputs information indicating the extracted candidate installation positions for the terminal station and the map information to the combination candidate group generation unit 15.

The combination candidate group generation unit 15 (generation unit) acquires information indicating the candidate installation positions of the base station extracted by the base station candidate position extraction unit 12 and equipment information. The combination candidate group generation unit 15 also acquires information indicating the candidate installation positions of the terminal station extracted by the terminal station candidate position extraction unit 14 and map information. The combination candidate group generation unit 15 generates a set of candidates (first combination candidate group) for combinations of the candidate installation positions of the base station (first wireless station) and the terminal station (second wireless station) based on the acquired information. The combination candidate group generation unit 15 stores the information indicating the generated combination candidate group, the equipment information, and the map information in the memory unit 30.

The map visibility determination unit 16 (first determination unit) acquires information indicating the group of candidate combinations, facility information, and map information stored in the memory unit 30. The map visibility determination unit 16 performs a visibility determination for each of the acquired group of candidate combinations. As described above, the visibility determination in this embodiment is a determination of whether communication is possible between a base station and a terminal station based on a determination of the presence or absence of visibility or a calculation of the shielding rate. Details of the visibility determination process by the map visibility determination unit 16 will be described later.

The map visibility determination unit 16 extracts only combination candidates that are determined to be communicable. The map visibility determination unit 16 overwrites and updates the combination candidate group stored in the memory unit 30 with the combination candidate group that is determined to be communicable by a determination using map information. Note that instead of overwriting and updating as described above, the map visibility determination unit 16 may assign information (e.g., a visibility determination result flag) indicating whether or not each of the combination candidates included in the combination candidate group stored in the memory unit 30 has been determined to have visibility.

The point cloud data acquisition unit 21 acquires point cloud data, for example, from an external device. The point cloud data referred to here is three-dimensional point cloud data obtained by imaging a space. For example, the point cloud data is obtained by driving a mobile object such as a vehicle equipped with an MMS along roads surrounding the residential area to be evaluated. The facility information acquisition unit 11 outputs the acquired point cloud data to the data matching unit 22.

The point cloud data acquisition unit 21 may acquire the point cloud data from an external storage device, or from an external device via a communication network. Alternatively, the point cloud data may be pre-stored in the storage unit 30, and the point cloud data acquisition unit 21 may acquire the point cloud data from the storage unit 30.

The data matching unit 22 acquires map information output from the map information acquisition unit 13. The data matching unit 22 also acquires point cloud data output from the point cloud data acquisition unit 21. The data matching unit 22 attempts to align the coordinate system of the map information with the coordinate system of the point cloud data, and aligns positions (coordinates) included in the map information with positions (coordinates) included in the point cloud data. If necessary, the data matching unit 22 corrects positions included in the group of combination candidates stored in the storage unit 30 so that they become positions based on the coordinate system of the point cloud data. The data matching unit 22 stores the acquired point cloud data in the storage unit 30.

In general, the coordinate system of the map information and the coordinate system of the point cloud data often use a common coordinate system, such as the World Geodetic System, so it is considered that there is often no need for coordinate matching processing by the data matching unit 22.

The point cloud visibility determination unit 23 (second determination unit) acquires information indicating the combination candidate group stored in the memory unit 30, and point cloud data. The point cloud visibility determination unit 23 performs visibility determination for each of the acquired combination candidates. As described above, visibility determination in this embodiment is a determination of whether communication is possible between a base station and a terminal station based on a determination of the presence or absence of visibility or a calculation of the shielding rate. Note that any conventional technology can be used for the visibility determination processing by the point cloud visibility determination unit 23.

The point cloud visibility determination unit 23 extracts only combination candidates that are determined to be communicable. The map visibility determination unit 16 overwrites and updates the combination candidates stored in the memory unit 30 with the combination candidates that are determined to be communicable by a determination using point cloud data. Note that instead of overwriting and updating as described above, the point cloud visibility determination unit 23 may update information (e.g., a visibility determination result flag) indicating whether or not each of the combination candidates stored in the memory unit 30 has been determined to have reasonable visibility.

The storage unit 30 stores the above-mentioned combination candidate group, facility information, map information, and point cloud data. Note that the storage unit 30 does not need to store all facility information, all map information, and all point cloud data, but only needs to store at least the facility information and map information required for the determination process by the map visibility determination unit 16, and at least the point cloud data required for the determination process by the point cloud visibility determination unit 23.

The memory unit 30 is composed of a storage medium such as a hard disk drive (HDD), flash memory, an electrically erasable programmable read only memory (EEPROM), a random access read/write memory (RAM), a read/write memory (ROM), or any combination of these storage media.

For example, the base station candidate position extraction unit 12, the terminal station candidate position extraction unit 14, the combination candidate group generation unit 15, the map visibility determination unit 16, the data matching unit 22, and the point cloud visibility determination unit 23 may be configured as components of a single control unit (not shown). In this case, the control unit is realized, for example, by a hardware processor such as a CPU (Central Processing Unit) executing a program (software). Alternatively, the control unit may be realized by collaboration between software and hardware. The program read by the CPU may be stored in advance in a storage medium such as the storage unit 30 provided in the station placement design support device 1.

The combination candidate group output unit 40 (output unit) acquires information indicating a combination candidate group (second combination candidate group) that is generated by the combination candidate group generation unit 15 and that has been subsequently narrowed down by the judgment process by the map visibility judgment unit 16 and the judgment process by the point cloud visibility judgment unit 23 from the storage unit 30. The combination candidate group output unit 40 outputs the information indicating the acquired combination candidate group to an external device.

The combination candidate group output unit 40 is configured to include, for example, a communication interface for outputting information indicating the combination candidate group to an external device. The combination candidate group output unit 40 may also function as a display unit that displays the combination candidate group. In this case, the combination candidate group output unit 40 is configured to include a display device such as a liquid crystal display (LCD) or an organic electroluminescence (EL) display.

[Operation of the channel placement design assistance device]
An example of the operation of the station placement design assistance device 1 in the first embodiment will be described below. Fig. 2 is a flowchart showing the operation of the station placement design assistance device 1 in the first embodiment of the present invention.

The equipment information acquisition unit 11 acquires equipment information, for example, from an external device (step S1). The equipment information acquisition unit 11 outputs the acquired equipment information to the base station candidate position extraction unit 12.

The map information acquisition unit 13 acquires map information, for example, from an external device. The map information acquisition unit 13 outputs the acquired map information to the terminal station candidate position extraction unit 14 and the data matching unit 22 (step S2).

The base station candidate position extraction unit 12 acquires the equipment information output from the equipment information acquisition unit 11. The base station candidate position extraction unit 12 extracts base station installation candidate positions based on the acquired equipment information (step S3). The base station candidate position extraction unit 12 outputs information indicating the extracted base station installation candidate positions and equipment information to the combination candidate group generation unit 15.

The terminal station candidate position extraction unit 14 acquires the map information output from the map information acquisition unit 13. The terminal station candidate position extraction unit 14 extracts candidate installation positions for the terminal station based on the acquired map information (step S4). The terminal station candidate position extraction unit 14 outputs information indicating the extracted candidate installation positions for the terminal station and the map information to the combination candidate group generation unit 15.

The combination candidate group generation unit 15 acquires information indicating the candidate installation positions of the base station extracted by the base station candidate position extraction unit 12 and facility information. The combination candidate group generation unit 15 also acquires information indicating the candidate installation positions of the terminal station extracted by the terminal station candidate position extraction unit 14 and map information. The combination candidate group generation unit 15 generates a combination candidate group that is a set of candidates for combinations of the candidate installation positions of the base station and the terminal station based on the acquired information (step S5). The combination candidate group generation unit 15 stores the information indicating the generated combination candidate group, facility information, and map information in the storage unit 30.

The map visibility determination unit 16 acquires information indicating the group of candidate combinations, facility information, and map information stored in the memory unit 30. The map visibility determination unit 16 performs visibility determination for each of the acquired group of candidate combinations. The map visibility determination unit 16 narrows down the group of candidate combinations through visibility determination based on the map information by extracting only combination candidates that are determined to have visibility (step S6).

The map visibility determination unit 16 outputs information indicating the combination candidate group narrowed down based on the map information to the storage unit 30 (step S7). As a result, the combination candidate group stored in the storage unit 30 is overwritten and updated with the combination candidate group consisting of combination candidates that have been determined to have visibility by the visibility determination using the map information. The map visibility determination unit 16 may output information indicating the combination candidate group narrowed down based on the map information to an external device. Details of the operation of step S6 will be described later with reference to FIG. 3.

The data matching unit 22 receives information from the storage unit 30 indicating the combination candidate group narrowed down based on the map information output in step S7 and the coordinates of the base station installation candidate positions and terminal station installation candidate positions included in the combination candidate group (step S8). Note that the information may be input to the data matching unit 22 from an external device.

For example, the station design support device 1 may be a device that has a device that performs the visibility judgment based on the map information described above and a device that performs the visibility judgment based on the point cloud data described below separately. In the flowchart of FIG. 2, the visibility judgment based on the map information and the visibility judgment based on the point cloud data are performed in a series of operations. However, the visibility judgment based on the map information and the visibility judgment based on the point cloud data may each be performed separately.

The point cloud data acquisition unit 21 acquires point cloud data, for example, from an external device (step S9). The point cloud data acquisition unit 21 outputs the acquired point cloud data to the data matching unit 22.

The data matching unit 22 acquires the point cloud data output from the point cloud data acquisition unit 21. The data matching unit 22 attempts to match the coordinate system of the map information with the coordinate system of the point cloud data, and matches the positions (coordinates) included in the map information with the positions (coordinates) included in the point cloud data. The data matching unit 22 stores the acquired point cloud data in the memory unit 30.

The point cloud visibility determination unit 23 acquires information indicating the combination candidate group stored in the storage unit 30 and point cloud data. The point cloud visibility determination unit 23 performs visibility determination for each of the combination candidates included in the acquired combination candidate group. The point cloud visibility determination unit 23 extracts only combination candidates that are determined to have visibility. The map visibility determination unit 16 narrows down the combination candidates by overwriting and updating the combination candidate group stored in the storage unit 30 with a combination candidate group consisting of combination candidates that are determined to have visibility by a visibility determination using the point cloud data (step S10). Details of the operation of step S10 will be described later with reference to FIG. 4.

The combination candidate group output unit 40 acquires information indicating a combination candidate group in which combination candidates have been narrowed down by the visibility judgment by the map visibility judgment unit 16 and the visibility judgment by the point cloud visibility judgment unit 23 from the storage unit 30. The combination candidate group output unit 40 outputs the acquired information indicating the combination candidate group to an external device (step S11). This completes the operation of the station placement design support device 1 shown in the flowchart of FIG. 2.

Below, we will explain in more detail the operation of the map visibility determination unit 16 in step S6 of the flowchart shown in Figure 2. Figure 3 is a flowchart showing an example of the operation of the visibility determination process by the map visibility determination unit 16 in the first embodiment of the present invention.

The map visibility determination unit 16 acquires information indicating the group of combination candidates, facility information, and map information stored in the memory unit 30. The map visibility determination unit 16 selects one combination candidate for which visibility determination has not yet been performed from the acquired group of combination candidates (step S601).

The map visibility determination unit 16 performs visibility determination between the candidate installation locations of the base station and the candidate installation locations of the terminal station indicated by the selected combination candidate (step S602). If the map visibility determination unit 16 determines that there is no visibility as a result of the visibility determination (step S602, NO), it deletes the selected combination candidate from the acquired combination candidate group (step S603).

The map visibility determination unit 16 repeats the operations from step S601 to step S603 described above until visibility determination has been performed for all combination candidates included in the acquired combination candidate group (step S604). If visibility determination has been performed for all combination candidates included in the acquired combination candidate group (step S604, YES), the process proceeds to step S7 of the flowchart shown in FIG. 2.

Below, we will explain in more detail the operation of the point cloud visibility determination unit 23 in step S10 of the flowchart shown in Figure 2. Figure 4 is a flowchart showing an example of the operation of the visibility determination process by the point cloud visibility determination unit 23 in the first embodiment of the present invention.

The point cloud visibility determination unit 23 acquires information indicating the combination candidate group stored in the memory unit 30 and point cloud data. The point cloud visibility determination unit 23 selects one combination candidate for which visibility determination has not yet been performed from the acquired combination candidate group (step S1001).

The point cloud visibility determination unit 23 performs visibility determination between the candidate installation positions of the base station and the candidate installation positions of the terminal station indicated by the selected combination candidate (step S1002). If the point cloud visibility determination unit 23 determines that there is no visibility as a result of the visibility determination (step S1002, NO), it deletes the selected combination candidate from the acquired combination candidate group (step S1003).

The point cloud visibility determination unit 23 repeats the operations from step S1001 to step S1003 until visibility determination is performed for all combination candidates included in the acquired combination candidate group (step S1004). If visibility determination is performed for all combination candidates included in the acquired combination candidate group (step S1004, YES), proceed to step S11 of the flowchart shown in FIG. 2.

As a result of the visibility determination by the station placement design support device 1 of this embodiment, four cases as shown in Figure 37 are possible. Figure 37 is a diagram for explaining the four cases that can be considered as a result of the visibility determination.

As shown in Figure 37, the four possible cases as a result of visibility assessment by the station design support device 1 are combinations of cases where the result of the visibility assessment based on map information is "visibility available" and "no visibility," and cases where the result of the visibility assessment based on point cloud data is "visibility available" and "no visibility."

As shown in FIG. 37, here, the case where the result of the visibility judgment based on the map information is "visibility available" and the result of the visibility judgment based on the point cloud data is "visibility available" is referred to as "case (1)." Moreover, the case where the result of the visibility judgment based on the map information is also "visibility available" and the result of the visibility judgment based on the point cloud data is "no visibility" is referred to as "case (2)." Moreover, the case where the result of the visibility judgment based on the map information is "no visibility" and the result of the visibility judgment based on the point cloud data is "visibility available" is referred to as "case (3)." Moreover, the case where the result of the visibility judgment based on the map information is "no visibility" and the result of the visibility judgment based on the point cloud data is also "no visibility" is referred to as "case (4)."

[Effect of reducing the amount of calculation]
The effect of reducing the amount of calculation by narrowing down combination candidates in advance using map information will be described below. Fig. 5 is a diagram for explaining the effect of reducing the amount of calculation by the station placement design assistance device 1 in the first embodiment of the present invention.

Figures 5A and 5B show the visibility determination based on map information by the map visibility determination unit 16. On the other hand, Figures 5C and 5D show the visibility determination based on point cloud data by the point cloud visibility determination unit 23.

As shown, in (A) and (B) of Figure 5, the visibility assessment is based on map information, so the presence of residential walls, roadside trees, traffic signs, etc. that are not included in the map information are not taken into consideration in the visibility assessment. On the other hand, in (C) and (D) of Figure 5, the visibility assessment is based on point cloud data, so the presence of residential walls, roadside trees, road signs, etc. that are included in the point cloud data are also taken into consideration in the visibility assessment.

Figures 5 (A) to (D) all show examples of possible combinations when a location on the wall of house h1 is selected as a possible installation location for a terminal station.

5A shows a case where a visibility determination is performed based on map information, with utility pole p1 as the candidate installation location for the base station. In this case, as shown in the figure, the visibility between the candidate installation location for the base station and the candidate installation location for the terminal station is blocked by a house h2, so the result of the visibility determination is "no visibility."

On the other hand, (B) of Figure 5 shows a case where utility pole p2 is set as a candidate installation location for the base station and visibility is determined based on map information. In this case, as shown in the figure, the visibility between the candidate installation location for the base station and the candidate installation location for the terminal station is not blocked by a house h2 or the like, so the result of the visibility determination is "visible."

Figure 5 (C) shows a case where a visibility determination is performed based on point cloud data, with utility pole p1 as the candidate installation location for the base station. In this case, as shown in the figure, the visibility between the candidate installation location for the base station and the candidate installation location for the terminal station is blocked by a house h2, so the result of the visibility determination is "no visibility."

On the other hand, (D) of Figure 5 shows a case where a visibility determination is performed based on point cloud data with utility pole p2 as the candidate installation location for the base station. In this case, as shown in the figure, the visibility between the candidate installation location for the base station and the candidate installation location for the terminal station is not blocked by, for example, house h2, the fence of house h2, roadside trees, road signs, etc., so the result of the visibility determination is "visible."

The reason why the station placement design support device 1 of this embodiment has the effect of reducing the amount of calculation is based on the assumption that in an actual environment, most situations are as shown in case (1) or case (4) in FIG. 37. For example, in a situation where visibility is determined to be available by a visibility determination based on map information, as in the case of FIG. 5(B), it is highly likely that the situation is also determined to be available by a visibility determination based on point cloud data, as in the case of FIG. 5(D). Similarly, in a situation where visibility is determined to be unavailable by a visibility determination based on map information, as in the case of FIG. 5(A), it is highly likely that the situation is also determined to be unavailable by a visibility determination based on point cloud data, as in the case of FIG. 5(C).

However, although the possibility is low, a situation like case (2) shown in FIG. 37 may occur. For example, even if a situation is determined to have visibility based on map information as in FIG. 5(B), a situation may be determined to have no visibility based on point cloud data as in FIG. 5(C). For example, the visibility between the candidate installation positions of the base station and the candidate installation positions of the terminal station may be blocked by any object other than a building that can block the propagation of radio waves, such as structures such as residential fences and elevated roads, road signs and signboards, plants such as roadside trees and garden trees, and raised ground, which are not included in the map information. Therefore, the station placement design support device 1 in this embodiment performs a visibility judgment based on point cloud data for combination candidates that are determined to have visibility based on map information.

And, although less likely, a situation like case (3) shown in Figure 37 may also occur. For example, when a visibility determination is performed based on map information in which the information showing the outline of a building contained in two-dimensional map information is assigned the height of the highest point of the building, another building may become an obstruction and block the visibility between the candidate installation location of the base station and the candidate installation location of the terminal station. For example, in a situation like that of Figures 10 and 13 described later, a visibility determination based on map information may determine that there is no visibility (based on the height of the highest point of the building), but a visibility determination based on point cloud data may determine that there is visibility (when there is actually visibility).

Here, the determination times required for visibility determination in the cases of (A), (B), (C), and (D) in Figure 5 are represented as ta, tb, tc, and td, respectively. In this case, since the map information is data with a relatively low density (low amount of information) compared to the point cloud data, the determination times ta and tb for visibility determination based on the map information are significantly shorter than the determination times tc and td for visibility determination based on the point cloud data.

Furthermore, regardless of whether visibility is available or not, the judgment time for determining visibility based on map information for each combination candidate is roughly the same, so ta and tb are roughly the same judgment times. Similarly, regardless of whether visibility is available or not, the judgment time for determining visibility based on point cloud data for each combination candidate is roughly the same, so tc and td are roughly the same judgment times.

From the above, it can be said that the relationship shown in equation (1) below holds.

ta≒tb<<tc≒td...(1)

Here, the total number of combinations of all the candidate installation locations of the base station and all the candidate installation locations of the terminal station within the evaluation area is denoted as M. Furthermore, among these M combination candidates, the number of combinations in which there is line of sight between the candidate installation locations of the base station and the candidate installation locations of the terminal station is denoted as n.

In this embodiment, the station placement design support device 1 first narrows down the number of combination candidates included in the combination candidate group by performing a visibility judgment based on map information, and then performs a visibility judgment for each of the narrowed down combination candidates based on point cloud data, so that the visibility judgment can be completed in approximately the judgment time shown in the following formula (2).

ta×n+tb×(M-n)+tc×n
Here, if ta = tb,
ta×M+tc×n...(2)

On the other hand, when a visibility assessment is performed based on point cloud data for all combinations of candidate installation locations for base stations and all candidate installation locations for terminal stations within the evaluation area, as in the conventional technology, the assessment time required is approximately the same as shown in the following equation (3).

tc×n+td×(M−n)
Here, if tc = td,
tc×M...(3)

As described above, since ta<<tc, it can be said that the station placement design support device 1 in this embodiment can achieve a reduction in the decision time by approximately tc x (M-n).

As described above, the map information in this embodiment is obtained by adding information indicating the height of each building to the position information of the building included in the two-dimensional map data. Generally, coordinate information based on two-dimensional map information is coordinate information consisting of coordinates at intervals of several meters, and coordinate information based on two-dimensional point cloud data is coordinate information consisting of coordinates at intervals of several centimeters. Therefore, the amount of information in the coordinate information based on the two-dimensional point cloud data is about 10,000 (= ¹⁰⁰² ) times larger than the amount of information in the coordinate information based on the two-dimensional map information.

As described above, the station placement design support device 1 in the first embodiment of the present invention performs a visibility assessment in advance using low-density data (three-dimensional map information) representing the positions of obstructions present within the evaluation area. This allows the station placement design support device 1 to exclude combinations of candidate installation positions for both stations that are presumed to have no clear visibility, and narrow down the combination candidates. After that, the station placement design support device 1 performs a more detailed visibility assessment for each of the narrowed-down combination candidates using high-density data (three-dimensional point cloud data) representing the positions of obstructions present within the evaluation area. This allows the station placement design support device 1 to identify combination candidates with visibility.

In this way, the station placement design support device 1 of the present invention can reduce the number of detailed visibility assessments that need to be performed using high-density data by performing visibility assessments in advance using low-density data.

By having such a configuration, the station placement design support device 1 in the first embodiment of the invention can appropriately present combinations of candidate installation locations for base stations and candidate installation locations for terminal stations while suppressing an increase in the amount of calculations required for determining visibility.

Second Embodiment
The station location design support device 1 in the second embodiment will be described below. In general, even if there is no line of sight between a base station and a terminal station, a radio wave propagation path may be secured by, for example, the reflection of radio waves on the wall of a building, and communication may be possible. Even if it is determined that there is no line of sight between the candidate installation positions of the base station and the candidate installation positions of the terminal station by the line of sight determination based on map information, the station location design support device 1 in this embodiment further determines the presence or absence of line of sight that allows for the reflection of radio waves on walls, etc., using the map information.

Hereinafter, the visibility that allows for the reflection of radio waves from walls and the like is referred to as "reflection visibility," and the judgment of the presence or absence of reflection visibility is referred to as "reflection visibility judgment." The station placement design support device 1 of the second embodiment can present more combination candidates, including not only combination candidates that are judged to have visibility, but also combination candidates that are judged to have reflection visibility.

[Determining visibility based on map information]
The following describes the visibility determination based on map information by the station location design support device 1 of this embodiment. The station location design support device 1 of this embodiment first performs visibility determination and reflection visibility determination on a horizontal plane, and then performs visibility determination and reflection visibility determination on a vertical cross section.

Below, we will explain the visibility judgment and reflection visibility judgment by the station placement design support device 1. Figure 6 is a diagram for explaining the visibility judgment and reflection visibility judgment on a horizontal plane by the station placement design support device 1 of the second embodiment of the present invention.

Figure 6 shows utility pole p11, which is a candidate installation location for the base station, and base station b11 when installed on utility pole p11. Figure 6 also shows wall position h11-1, which is the center position of one wall of house h11, which is a candidate installation location for a terminal station, wall position h11-2, which is the end position of one wall of house h11, and terminal station t11 when installed at wall position h11-1 and wall position h11-2. Figure 6 also shows houses h12 and h13, which may act as obstructions blocking the propagation of radio waves between base station b11 and terminal station t11.

The map visibility determination unit 16 first performs a visibility determination on a horizontal plane between utility pole p11, which is a candidate installation location for the base station, and the wall of house h11, which is a candidate installation location for the terminal station. As shown in FIG. 6, for example, the view between utility pole p11 and wall position h11-1 is blocked by house h12, so it can be said that there is no view between utility pole p11 and house h11. In this case, the map visibility determination unit 16 performs a reflection visibility determination on a horizontal plane between utility pole p11, which is a candidate installation location for the base station, and the wall of house h11, which is a candidate installation location for the terminal station.

As shown in Figure 6, if one wall surface of a house h13 is a reflective surface m11 that reflects radio waves, the position of the mirror image of utility pole p11 when viewed from wall position h11-2 is the position of mirror image p11m. In addition, the intersection of the straight line connecting wall position h11-2 and mirror image p11m with the reflective surface m11 is the reflection point r11, which is the position where the radio waves are reflected.

The map visibility determination unit 16 determines that there is visibility between the utility pole p11 and the reflection point r11, and also between the reflection point r11 and the wall position h11-2, and therefore that there is visibility between the utility pole p11 and the wall position h11-2 on the horizontal plane.

Next, the map visibility determination unit 16 performs a visibility determination on a vertical cross section between the utility pole p11, which is a candidate installation location for the base station, and the wall of the house h11, which is a candidate installation location for the terminal station.

Figure 7 is a diagram for explaining visibility determination and reflection visibility determination on a vertical cross section by the station location design support device 1 of the second embodiment of the present invention.

Figure 7 (A) shows the visibility assessment on a vertical cross section between utility pole p11 and wall position h11-1. On the other hand, Figure 7 (B) shows the reflected visibility assessment on a vertical cross section between utility pole p11 and wall position h11-2.

Figures 7A and 7B show utility pole p11, which is a candidate installation location for the base station, and base station b11 when installed on utility pole p11. Figures 7A and 7B also show wall position h11-1, which is the center position of one wall of house h11, which is a candidate installation location for a terminal station, wall position h11-2, which is the end position of one wall of house h11, and terminal station t11 when installed at wall position h11-1 and wall position h11-2. Figures 7A and 7B also show houses h12 and h13, which may be obstructions that block the propagation of radio waves between base station b11 and terminal station t11. As shown in the figure, the height of house h13 is lower than that of house h12.

As shown in (A) of Figure 7, for example, the view between utility pole p11 and wall position h11-1 is blocked by house h12, and it can be said that there is no view between utility pole p11 and house h11 on a vertical cross section.

However, if the height of house h12 is, for example, about the same as the height of house h13, it can be said that there is visibility on the vertical cross section between utility pole p11 and wall position h11-1. In such a case, even if it is determined that there is no visibility based on the visibility determination on the horizontal plane, the map visibility determination unit 16 can recognize that there is actually a possibility of visibility based on the visibility determination on the vertical cross section.

When the map visibility determination unit 16 determines that there is visibility in at least one of the visibility determinations on the horizontal plane and the visibility determination on the vertical cross section, it determines that there is visibility between the candidate installation locations of the base station and the candidate installation locations of the terminal station, and includes this combination candidate in the group of combination candidates (i.e., does not delete this combination candidate from the group of combination candidates).

If the map visibility determination unit 16 determines that there is no visibility in both the visibility determination on the horizontal plane and the visibility determination on the vertical cross section, it determines that there is no visibility between the candidate installation location of the base station and the candidate installation location of the terminal station, and removes this combination candidate from the group of combination candidates.

On the other hand, as shown in Figure 7B, for example, if a straight line is drawn between utility pole p11 and wall position h11-2 on a vertical cross section, it can be seen that the position of reflection point r11 is higher than the height of house h13 that forms reflection surface m11 in Figure 6. Therefore, the map visibility determination unit 16 can recognize that there is no reflection visibility because there is actually no wall at the position of reflection point r11 shown in Figure 7B.

In this way, even if it is determined that there is reflective visibility based on a reflective visibility assessment on a horizontal plane, the map visibility assessment unit 16 can recognize that there is actually no reflective visibility based on a visibility assessment on a vertical cross section.

When it is determined that there is visibility of reflection in both the visibility determination on the horizontal plane and the visibility determination on the vertical cross section, the map visibility determination unit 16 determines that there is visibility of reflection between the candidate installation location of the base station and the candidate installation location of the terminal station, and includes this combination candidate in the combination candidate group (i.e., does not delete this combination candidate from the combination candidate group).

When the map visibility determination unit 16 determines that there is no visibility in at least one of the reflection visibility determination on the horizontal plane and the reflection visibility determination on the vertical cross section, it determines that there is no visibility between the candidate installation location of the base station and the candidate installation location of the terminal station, and removes this combination candidate from the group of combination candidates.

Figure 38 is a diagram showing the relationship between the results of visibility assessment on a horizontal plane and the results of visibility assessment on a vertical cross section, and whether or not it is subject to visibility assessment based on point cloud data. Figure 38 shows whether or not a candidate combination to be evaluated is subject to visibility assessment based on point cloud data, depending on the results of visibility assessment on a horizontal plane and the results of visibility assessment on a vertical cross section.

As shown in FIG. 38, for example, case (A) is a case where a visibility assessment on a horizontal plane determines that there is no visibility, and a visibility assessment on a vertical cross section also determines that there is no visibility. In such a case (A), the candidate combination to be evaluated is not subject to visibility assessment based on the point cloud data. Also, case (B) is a case where a visibility assessment on a horizontal plane determines that there is no visibility, and a visibility assessment on a vertical cross section determines that there is visibility. In such a case (B), the candidate combination to be evaluated is subject to visibility assessment based on the point cloud data.

Case (C) is a case where visibility is determined to be available based on visibility assessment on a horizontal plane. In such a case (C), there is no need to perform visibility assessment on a vertical cross section, and the candidate combinations to be evaluated are subject to visibility assessment based on point cloud data. With this configuration, the station placement design support device 1 of this embodiment can efficiently determine whether or not a combination is subject to visibility assessment based on point cloud data.

Figure 39 is a diagram showing the relationship between the results of reflection visibility judgment on a horizontal plane and the results of reflection visibility judgment on a vertical cross section, and whether or not it is subject to visibility judgment based on point cloud data. Figure 39 shows whether or not a candidate combination to be evaluated is subject to visibility judgment based on point cloud data, depending on the results of reflection visibility judgment on a horizontal plane and the results of reflection visibility judgment on a vertical cross section.

As shown in FIG. 39, for example, case (D) is a case where it is determined that there is no reflection visibility based on a reflection visibility assessment on a horizontal plane. In such a case (D), there is no need to perform a reflection visibility assessment on a vertical cross section, and the candidate combination to be evaluated is not subject to visibility assessment based on point cloud data. With this configuration, the station placement design support device 1 of this embodiment can efficiently determine whether or not a combination is subject to visibility assessment based on point cloud data.

Case (E) is a case where a reflection visibility assessment on a horizontal plane determines that there is reflection visibility, but a reflection visibility assessment on a vertical cross section determines that there is no reflection visibility. In such a case (E), the candidate combination to be evaluated is not subject to visibility assessment based on point cloud data. In such a case (F), a reflection visibility assessment on a horizontal plane determines that there is reflection visibility, but a reflection visibility assessment on a vertical cross section also determines that there is reflection visibility. In such a case (E), the candidate combination to be evaluated is subject to visibility assessment based on point cloud data.

[Operation of the channel placement design assistance device]
An example of the operation of the station placement design support device 1 in the second embodiment will be described below. Note that in the operation of the station placement design support device 1 in the second embodiment, the operations other than step S6 in the flowchart shown in Fig. 2 are the same as the operations of the station placement design support device 1 in the first embodiment described above. Therefore, only the operation of narrowing down the combination candidate group by the visibility judgment based on the map information shown in step S6 in the flowchart in Fig. 2 will be described below.

Figure 8 is a flowchart showing an example of the operation of visibility determination processing by the map visibility determination unit 16 in the second embodiment of the present invention.

The map visibility determination unit 16 acquires information indicating the group of combination candidates, facility information, and map information stored in the memory unit 30. The map visibility determination unit 16 selects one combination candidate for which visibility has not yet been determined from the acquired group of combination candidates (step S611).

The map visibility determination unit 16 performs visibility determination on a horizontal plane between the candidate installation positions of the base station and the candidate installation positions of the terminal station indicated by the selected combination candidate (step S612). If the map visibility determination unit 16 determines that there is no visibility on the horizontal plane as a result of the visibility determination (step S612, NO), it performs visibility determination on a vertical cross section between the candidate installation positions of the base station and the candidate installation positions of the terminal station (step S613).

The reason why the processing order is such that visibility assessment on the horizontal plane is followed by visibility assessment on the vertical cross section is that, as mentioned above, in case (C) of Figure 38, it is not necessary to perform visibility assessment on the vertical cross section, making it possible to perform an efficient visibility assessment.

If the map visibility determination unit 16 determines that there is no visibility on the vertical cross section as a result of the visibility determination (step S613, NO), it performs a reflection visibility determination on the horizontal plane between the candidate installation locations of the base station and the candidate installation locations of the terminal station (step S614).

If the map visibility determination unit 16 determines that there is visibility of reflection on the horizontal plane as a result of the reflection visibility determination (step S614, YES), it performs a visibility determination of reflection on a vertical cross section between the candidate installation location of the base station and the candidate installation location of the terminal station (step S615).

The reason why the processing order is such that the reflective visibility determination on the horizontal plane is followed by the reflective visibility determination on the vertical cross section is that, as mentioned above, in the case of (D) in Figure 38, it is not necessary to perform the reflective visibility determination on the vertical cross section, making it possible to perform an efficient reflective visibility determination.

On the other hand, if the map visibility determination unit 16 determines that there is no reflection visibility on the horizontal plane as a result of the reflection visibility determination (step S614, NO), it deletes the selected combination candidate from the obtained group of combination candidates (step S616).

If the map visibility determination unit 16 determines that there is no reflection visibility on the vertical cross section as a result of the reflection visibility determination (step S615, NO), it deletes the selected combination candidate from the obtained group of combination candidates (step S616).

The map visibility determination unit 16 repeats the operations from step S611 to step S616 until visibility determination and reflection visibility determination are performed for all combination candidates included in the acquired combination candidate group (step S617). When visibility determination and reflection visibility determination are performed for all combination candidates included in the acquired combination candidate group, the process proceeds to step S7 of the flowchart shown in FIG. 2.

As described above, the station location design support device 1 in the second embodiment of the present invention further determines the presence or absence of reflection visibility that allows reflection of radio waves from reflective surfaces such as building walls, even if it is determined by a visibility determination based on map information that there is no visibility between the candidate installation positions of the base station and the candidate installation positions of the terminal station. Even if it is determined that there is no visibility, the station location design support device 1 does not exclude from the group of combination candidates a combination candidate that is determined to have reflection visibility.

If necessary, steps S614 and S615 relating to the reflection line of sight determination in the flowchart shown in FIG. 8 may be omitted. In other words, a configuration may be used in which only a direct line of sight determination is performed between the candidate installation positions for the base station and the candidate installation positions for the terminal station. If necessary, steps S612 and S613 relating to the line of sight determination in the flowchart shown in FIG. 8 may be omitted. In other words, a configuration may be used in which only a reflection line of sight determination is performed between the candidate installation positions for the base station and the candidate installation positions for the terminal station.

By having such a configuration, the station placement design support device 1 in the second embodiment of the invention can appropriately present a larger number of combination candidates, including not only combination candidates that are determined to have line of sight, but also combination candidates that are determined to have reflection line of sight, while suppressing an increase in the amount of calculations in line of sight determination and reflection line of sight determination.

[Building shape based on map information]
In addition, if the height information contained in the map information only indicates the height of the highest point of each building, the map visibility determination unit 16 may assume that the shape of each building is columnar and perform visibility determination and reflection visibility determination.

That is, the map visibility determination unit 16 may determine that a building whose outline on the two-dimensional map is, for example, rectangular has a three-dimensional shape that is a rectangular parallelepiped. Similarly, the map visibility determination unit 16 may determine that a building whose outline on the two-dimensional map is, for example, circular has a three-dimensional shape that is a cylinder.

Figure 9 is a diagram for explaining an example of visibility determination by the station placement design support device 1 of the second embodiment of the present invention.

Figure 9 shows utility pole p11, which is a candidate installation location for the base station, and base station b11 when installed on utility pole p11. Figure 9 also shows wall position h11-1, which is the central position of one wall of house h11, which is a candidate installation location for a terminal station, and terminal station t11 when installed at wall position h11-1. Figure 9 also shows houses h12 and h13, which may act as obstructions blocking the propagation of radio waves between base station b11 and terminal station t11.

As shown in FIG. 9, the map visibility determination unit 16 considers the three-dimensional shapes of houses h11, h12, and h13, which have rectangular outlines on the two-dimensional map, to be rectangular prisms.

For example, if the three-dimensional shape of house h12 is deemed to be a rectangular parallelepiped shown by the dashed line in Fig. 9 based on the height of the highest point of house h12, the map visibility determination unit 16 determines that there is no visibility between utility pole p11 and wall position h11-1 because the view is blocked by house h12. Also, for example, if the three-dimensional shape of house h12 is deemed to be a rectangular parallelepiped shown by the solid line in Fig. 9 based on the height of the highest point of house h12, the map visibility determination unit 16 determines that there is visibility between utility pole p11 and wall position h11-1 because the view is not blocked by house h12.

In addition, when the height information included in the map information includes not only information indicating the height of the highest point of each building, but also information regarding the shape of the buildings, such as the shape and inclination angle of the roof of each building, the map visibility determination unit 16 may also take into account the information regarding the shape of the buildings when making visibility determination and reflection visibility determination.

Figure 10 is a diagram for explaining an example of visibility determination by the station placement design support device 1 of the second embodiment of the present invention.

Figure 10 shows utility pole p11, which is a candidate installation location for the base station, and base station b11 when installed on utility pole p11. Figure 10 also shows wall position h11-1, which is the central position of one wall of house h14, which is a candidate installation location for a terminal station, and terminal station t11 when installed at wall position h11-1. Figure 10 also shows houses h15 and h16, which may act as obstructions blocking the propagation of radio waves between base station b11 and terminal station t11.

As shown in FIG. 10, between the utility pole p11, which is a candidate installation location for the base station b11, and the wall position h11-1 of the house h14, which is a candidate installation location for the terminal station t11, there are houses h15 and h16, both of which have gable roofs.

As shown in Figure 9 above, if the shape of house h15 is deemed to be a rectangular parallelepiped based on the height of its highest point, the map visibility determination unit 16 will determine that there is no visibility between utility pole p11 and wall position h11-1 because the visibility is blocked by house h15. However, if information about the shape of the building is also available, the map visibility determination unit 16 can make a visibility determination taking into account, for example, the shape of the roof of house h15.

Figures 11 and 12 are diagrams for explaining an example of visibility determination by the station placement design support device 1 of the second embodiment of the present invention. Figure 11 shows the positional relationship of objects on a horizontal plane in the area shown in Figure 10. As shown in Figure 11, according to the visibility determination on the horizontal plane, it is determined that there is no visibility between utility pole p11 and wall position h11-1 because it is blocked by houses h16 and h15.

On the other hand, FIG. 12 shows the positional relationship of objects on a vertical cross section in the area shown in FIG. 10. FIG. 12 shows the position rf15 of the roof of house h15 on the vertical cross section, and the position rf16 of the roof of house h16 on the vertical cross section. For reference, the position of the roof of house h14 on the same vertical cross section is the highest position (same as the height of house h14) in this example. As shown in FIG. 12, although the straight line connecting utility pole p11 and wall position h11-1 passes through a position lower than the height of the highest point of house h15, it passes through a position higher than the position rf15 of the roof of house h15 on the vertical cross section and the position rf16 of the roof of house h16 on the vertical cross section, so the map visibility determination unit 16 can recognize that this combination candidate has visibility.

[Determining visibility using the Fresnel zone shielding factor]
In addition, the map visibility determination unit 16 may perform the visibility determination taking into account the shielding rate of the Fresnel zone, rather than simply performing the visibility determination based on the visibility on a straight line connecting the candidate installation positions of the base station and the candidate installation positions of the terminal station.

Actual electromagnetic waves do not propagate only along a straight line between two opposing wireless stations, but also within an elliptical path area called a Fresnel zone. Therefore, in order to more accurately determine whether or not there is line of sight between two opposing wireless stations, it is necessary to determine whether or not there is line of sight while taking into account the effects of obstructions present within the Fresnel zone. The Fresnel zone radius of the millimeter wave band is a maximum of about 25 cm when transmitting a distance of 50 m using electromagnetic waves in the 60 GHz band, for example.

Figure 13 is a diagram for explaining an example of visibility determination by the station placement design support device 1 of the second embodiment of the present invention.

Figure 13 shows utility pole p11, which is a candidate installation location for the base station, and base station b11 when installed on utility pole p11. Figure 13 also shows wall position h11-1, which is the central position of one wall of house h11, which is a candidate installation location for the terminal station, and terminal station t11 when installed at wall position h11-1. Figure 13 also shows houses h12 and h13, which may act as obstructions blocking the propagation of radio waves between base station b11 and terminal station t11. Figure 13 also shows Fresnel zone fz11 when radio waves are transmitted and received between base station b11 and terminal station t11.

As shown in Figure 13, the line of sight between utility pole p11, which is a candidate installation location for base station b11, and wall position h11-1, which is a candidate installation location for terminal station t11, is blocked by the wall of house h12. Figure 13 also shows cross section cs11 of Fresnel zone fz11 at the position of the wall of house h12 where the line of sight is blocked.

As shown in the figure, the area of cross section cs13 where the view is blocked by house h12 is approximately half of the lower part of cross section cs13 (i.e., the blocking rate can be said to be approximately 50%). Therefore, although there is no view in a straight line between utility pole p11 and wall position h11-1, it is possible that communication is possible by radio waves transmitted and received between base station b11 and terminal station t11 passing through the upper range of cross section cs11 of Fresnel zone fz11.

Figures 14 and 15 are figures for explaining an example of visibility determination by the station placement design support device 1 of the second embodiment of the present invention.

Figure 14 shows the positional relationship of objects on a horizontal plane in the area shown in Figure 13. As shown in Figure 14, according to a visibility determination on the horizontal plane, it is determined that there is no visibility between utility pole p11 and wall position h11-1 because it is blocked by house h12. Furthermore, even if Fresnel zone fz11 is taken into account, on the horizontal plane, Fresnel zone fz11 is blocked by house h12.

On the other hand, Figure 15 shows the positional relationship of objects on a vertical cross section in the area shown in Figure 10. As shown in Figure 15, according to the visibility judgment on the vertical cross section, it is judged that there is no visibility between the utility pole p11 and the wall position h11-1 because it is blocked by the house h12. However, when the Fresnel zone fz11 is taken into consideration, it can be seen that at least the upper part of the Fresnel zone fz11 is not blocked by the house h12 on the vertical cross section. Therefore, the map visibility judgment unit 16 may judge that there is visibility when, for example, the blocking rate at the cross section cs11 of the Fresnel zone f11 is equal to or greater than a predetermined value.

In this way, the map visibility determination unit 16 can perform a more accurate visibility determination by determining the presence or absence of visibility taking into account the shielding rate of the Fresnel zone even when there is no visibility on a straight line connecting the candidate installation positions of the base station and the candidate installation positions of the terminal station. This allows the station placement design support device 1 to present more combination candidates.

[Reflection visibility determination allowing multiple reflections]
In this embodiment, the map visibility determination unit 16 performs a reflection visibility determination including one reflection, but the map visibility determination unit 16 may be configured to perform a reflection visibility determination including two or more reflections.

Figures 16 to 23 are figures for explaining an example of visibility determination by the station placement design support device 1 of the second embodiment of the present invention.

Figures 16 to 23 show utility pole p11, which is a candidate installation location for the base station, and base station b11 when installed on utility pole p11. Figures 16 to 23 also show wall position h11-1, which is the center position of one wall of house h11, which is a candidate installation location for a terminal station, and wall position h11-2, which is the end position of one wall of house h11, and terminal station t11 when installed at wall position h11-1 and wall position h11-2, respectively. Figures 16 to 21 also show houses h12, h13, h17, and h18, which may become obstructions that block the propagation of radio waves between base station b11 and terminal station t11.

Note that Figures 16 to 21 are diagrams showing the positional relationships of the above-mentioned objects on a horizontal plane, and these positional relationships are common to Figures 16 to 21. Also, the positional relationship between utility pole p11, which is a candidate installation location for base station b11, and house h11, which has wall positions h11-1 and h11-2, which are candidate installation locations for terminal station t11, house h12, and house h13 shown in Figures 16 to 21 is the same as the positional relationship between utility pole p11 and each house shown in the above-mentioned Figure 6.

As shown in Figure 16, on the horizontal plane, there is no line of sight between utility pole p11, which is a candidate installation location for the base station device, and the wall of house h11, which is a candidate installation location for the terminal station, due to the presence of house h12. Therefore, the map visibility determination unit 16 performs a reflection visibility determination that allows multiple reflections.

First, the map visibility determination unit 16 extracts candidates for wall surfaces that can be reflective surfaces. Figure 17 shows six reflective surface candidates (reflective surface candidates α, β, γ, δ, ε, ζ) that have been extracted. Figure 17 shows areas that can be the propagation path of radio waves from base station b11 to each reflective surface candidate.

Next, the map visibility determination unit 16 identifies the position of the mirror image of the base station b11 based on each of the extracted reflecting surface candidates. As shown in FIG. 18, the position of the mirror image of the base station b11 based on the reflecting surface candidate α is the position of mirror image A. The position of the mirror image of the base station b11 based on the reflecting surface candidate β is the position of mirror image B. The position of the mirror image of the base station b11 based on the reflecting surface candidate γ is the position of mirror image C. The position of the mirror image of the base station b11 based on the reflecting surface candidate δ is the position of mirror image D. The position of the mirror image of the base station b11 based on the reflecting surface candidate ε is the position of mirror image E (note that the positional relationship between the reflecting surface candidate ε and the mirror image E shown in FIG. 18 to FIG. 20 is the same as the positional relationship between the reflecting surface m11 and the mirror image p11m shown in FIG. 6 described above). The position of the mirror image of the base station b11 based on the reflecting surface candidate ζ is the position of mirror image F.

Next, the map visibility determination unit 16 identifies a position that is further mirrored by another reflecting surface candidate, which is a wall surface of a building where the reflected wave reflected by the reflecting surface candidate reaches (i.e., the position of the mirror image of the identified mirror image). Specifically, as shown in FIG. 19, for example, the wall surface of house h18 where the reflected wave reflected by the reflecting surface candidate β reaches is reflecting surface candidate η. The position of the mirror image of mirror image B by reflecting surface candidate η is the position of mirror image G.

On the other hand, as shown in Figure 19, it can be seen that the reflected wave reflected by the candidate reflecting surface ε reaches wall position h11-2, which is the candidate installation location of terminal station t11. Therefore, the map visibility determination unit 16 can recognize that there is a combination candidate that has visibility after one reflection due to the reflection of the radio wave from the candidate reflecting surface ε.

Next, the map visibility determination unit 16 identifies the area through which the reflected wave that is re-reflected at the reflection surface candidate η propagates. As shown in FIG. 20, the map visibility determination unit 16 identifies reflection point C based on the route connecting the mirror image G and the wall surface position h11-1, which is the candidate installation location of the terminal station t11. The map visibility determination unit 16 identifies mirror image reflection point c based on reflection point C and reflection surface candidate β. The map visibility determination unit 16 identifies reflection point B based on utility pole p11, which is the candidate installation location of the base station, reflection surface candidate β, and mirror image reflection point c. By identifying reflection points B and reflection point C, the map visibility determination unit 16 can recognize that there is a combination candidate with reflection visibility due to the two reflections of the radio waves at reflection points B and C.

As shown in Figure 21, the propagation path of the radio wave reflected at reflection point A has line of sight to wall position h11-2 of the house h11, but has no line of sight to wall position h11-1 of the house h11 because house h12 is an obstruction (note that the position of reflection point A shown in Figures 20 to 21 is the same as the position of reflection point r11 shown in Figure 6 above). On the other hand, the propagation path of the radio wave reflected at reflection points B and C has line of sight to wall position h11-1 of the house h11, but has no line of sight to wall position h11-2 of the house h11 because house h12 is an obstruction.

Next, the map visibility determination unit 16 performs a reflection visibility determination on the vertical cross section. The upper diagram in Fig. 22 shows the propagation paths of radio waves reflected at reflection points B and C on a horizontal plane. The lower diagram in Fig. 22 shows the propagation paths of radio waves on the horizontal plane projected onto a vertical cross section.

Figure 23 shows in more detail the propagation path of radio waves on the vertical cross section shown in the lower diagram of Figure 22. The map visibility determination unit 16 determines that the position of the mirror image of utility pole p11, which is a candidate installation location for the base station, based on the reflecting surface candidate β is the position of mirror image B (mirror image base station). The map visibility determination unit 16 determines that the position of the mirror image of reflection point B on reflecting surface candidate β, based on the reflecting surface candidate η, is the position of mirror image reflection point b. The map visibility determination unit 16 determines that the position of the mirror image of reflection point C on reflecting surface candidate η, based on the reflecting surface candidate β, is the position of mirror image reflection point c. The map visibility determination unit 16 determines that the position of the mirror image of wall position h11-1 of house h11, which is a candidate installation location for the terminal station, based on the reflecting surface candidate η, is the position of the mirror image terminal station.

As shown in Figure 23, on the vertical cross section, utility pole p11, which is a candidate installation location for base station b11, reflection point B, and mirror image reflection point c are located immediately in front of each other. Also, on the vertical cross section, the position of the mirror image base station (mirror image B), the position of reflection point B, the position of reflection point C, and the position of the mirror image terminal station are located on the same straight line. Also, on the vertical cross section, mirror image reflection point b, reflection point C, and wall position h11-1, which is a candidate installation location for terminal station t11, are located on the same straight line.

Because reflection point B needs to be located on the wall of the house h17, the map visibility determination unit 16 compares the height of the wall of the house h17 with the height of reflection point B, and can recognize that there is no reflection visibility if the height of the wall of the house h17 is lower than the height of reflection point B. Also, because reflection point C needs to be located on the wall of the house h18, the map visibility determination unit 16 compares the height of the wall of the house h18 with the height of reflection point C, and can recognize that there is no reflection visibility if the height of the wall of the house h18 is lower than the height of reflection point C.

In addition, the station location design support device 1 may simulate radio wave propagation for each of the combination candidates narrowed down by the above-mentioned reflection visibility judgment, for example, using a ray tracing method (see non-patent documents 1 to 6), and further narrow down the combination candidates so that only combination candidates whose propagation quality value is equal to or greater than a predetermined value remain.

Third Embodiment
In the above-described embodiment, the station location design support device 1 is configured to determine visibility between a candidate installation position of a base station and a candidate installation position of a terminal station by first determining visibility on a horizontal plane and then determining visibility on a vertical cross section. On the other hand, in the station location design support device 1 in the third embodiment described below, the visibility determination in the height direction can be made simpler.

Figures 24 to 26 are figures for explaining an example of visibility determination by the station placement design support device 1 of the third embodiment of the present invention.

Figure 24 shows utility pole p11, which is a candidate installation location for the base station, and base station b11 when installed on utility pole p11. Figure 24 also shows wall position h11-1, which is the central position of one wall of house h11, which is a candidate installation location for a terminal station, and terminal station t11 when installed at wall position h11-1. Figure 24 also shows houses h12 and h13, which may act as obstructions blocking the propagation of radio waves between base station b11 and terminal station t11.

As shown in Figure 24, a house h12 exists between utility pole p11 and wall position 11-1. Therefore, when the map visibility determination unit 16 performs a visibility determination on the horizontal plane, it determines that there is no visibility on the horizontal plane for this combination candidate.

However, as shown in Figure 25, when viewed on a vertical cross section, the height of the house h12 is lower than the height of the straight line connecting the candidate installation locations of the base station b11 and the terminal station t11, so there may be visibility on the vertical cross section.

In this embodiment, the map visibility determination unit 16 sets a reference plane that is a horizontal plane at a predetermined height, and performs visibility determination on the reference plane. For example, the map visibility determination unit 16 sets the horizontal plane at the height at which base station b11 is installed on utility pole p11 as the reference plane. Figure 25 shows the reference plane rp11 set at the height at which base station b11 is installed.

As shown in Figure 26, when visibility is assessed on the reference plane, house h12, which does not meet the height of the reference plane, is not recognized as an obstruction by the map visibility assessment unit 16. This allows the map visibility assessment unit 16 to recognize that there is visibility between utility pole p11, which is a candidate installation location for the base station, and wall position h11-1, which is a candidate installation location for the terminal station.

In this way, the station location design support device 1 of the third embodiment performs visibility judgment on the reference plane, which is a horizontal plane, while taking into account height information by setting the reference plane, so that the visibility judgment on the vertical cross section mentioned above can be omitted.

[Operation of the channel placement design assistance device]
An example of the operation of the station placement design support device 1 in the third embodiment will be described below. Note that in the operation of the station placement design support device 1 in the third embodiment, the operations other than step S6 in the flowchart shown in Fig. 2 are the same as the operations of the station placement design support device 1 in the first embodiment described above. Therefore, only the operation of narrowing down the combination candidate group by the visibility judgment based on the map information shown in step S6 in the flowchart in Fig. 3 will be described below.

Figure 27 is a flowchart showing an example of the operation of visibility determination processing by the map visibility determination unit 16 in the third embodiment of the present invention.

The map visibility determination unit 16 sets a reference plane, which is a horizontal plane at a predetermined height (step S621). For example, the map visibility determination unit 16 sets the horizontal plane at the height at which the base station b11 is installed on the utility pole p11 as the reference plane.

The map visibility determination unit 16 acquires information indicating the group of combination candidates, facility information, and map information stored in the memory unit 30. The map visibility determination unit 16 selects one combination candidate for which visibility has not yet been determined from the acquired group of combination candidates (step S622).

The map visibility determination unit 16 performs visibility determination on the reference plane between the candidate installation positions of the base station and the candidate installation positions of the terminal station indicated by the selected combination candidate (step S623). If the map visibility determination unit 16 determines that there is no visibility on the reference plane as a result of the visibility determination (step S623, NO), it deletes the selected combination candidate from the acquired combination candidate group (step S624).

The map visibility determination unit 16 repeats the operations from step S622 to step S624 until visibility determination is performed for all combination candidates included in the acquired combination candidate group (step S625). When visibility determination is performed for all combination candidates included in the acquired combination candidate group, the process proceeds to step S7 of the flowchart shown in FIG. 2.

As described above, the station placement design support device 1 in the third embodiment of the present invention sets a reference plane that is a horizontal plane at a predetermined height and performs visibility judgment on the reference plane. As a result, the station placement design support device 1 can perform a simple visibility judgment in the height direction simply by performing visibility judgment on the reference plane that is a horizontal plane, so that the processing of visibility judgment on the vertical cross section described above can be omitted.

By having such a configuration, the station placement design support device 1 in the third embodiment of the present invention can appropriately present combination candidates while reducing the amount of calculation, particularly in determining visibility in the vertical direction.

Fourth Embodiment
In the above-described embodiment, the station location design support device 1 is configured to determine the visibility of reflection between the candidate installation positions of the base station and the candidate installation positions of the terminal station by first determining the visibility of reflection on a horizontal plane and then determining the visibility of reflection on a vertical cross section. On the other hand, in the station location design support device 1 in the fourth embodiment described below, the visibility of reflection in the height direction can be determined in a simpler configuration.

Figures 28 to 30 are figures for explaining an example of visibility determination by the station placement design support device 1 of the fourth embodiment of the present invention.

Figure 28 shows utility pole p11, which is a candidate installation location for the base station, and base station b11 when installed on utility pole p11. Figure 28 also shows wall position h11-2, which is the position of the end of one wall of house h11, which is a candidate installation location for a terminal station, and terminal station t11 when installed at wall position h11-2. Figure 28 also shows houses h12 and h13, which may act as obstructions blocking the propagation of radio waves between base station b11 and terminal station t11.

As shown in Figure 28, a house h12 exists between utility pole p11 and wall position 11-2. However, when the map visibility determination unit 16 performs a reflection visibility determination on a horizontal plane, it is able to identify the propagation path of the radio waves including reflection by reflection surface candidate ε (the wall of house h13), and therefore determines that there is reflection visibility on a horizontal plane for this combination candidate.

However, as shown in FIG. 29, since the height of the house h13 is lower than the height of the straight line connecting the candidate installation location of the base station b11 and the candidate installation location of the terminal station t11, there may be no wall at the reflection point, and there may be no visibility of the reflection on the vertical cross section.

In this embodiment, the map visibility determination unit 16 sets a reference plane, which is a horizontal plane at a predetermined height, and performs a reflection visibility determination on the reference plane. For example, the map visibility determination unit 16 sets the horizontal plane at the height at which base station b11 is installed on utility pole p11 as the reference plane. Figure 29 shows the reference plane rp11 set at the height at which base station b11 is installed.

As shown in Figure 30, when a reflection visibility determination is performed on the reference plane, house h13, which does not meet the height of the reference plane, is not recognized as a building having a wall that is subject to a reflection surface by the map visibility determination unit 16. As a result, the map visibility determination unit 16 can recognize that there is no reflection visibility between utility pole p11, which is a candidate installation location for the base station, and wall position h11-1, which is a candidate installation location for the terminal station, because there is no available reflection surface.

In this way, the station location design support device 1 of the fourth embodiment performs reflection visibility judgment on the reference plane, which is a horizontal plane, while taking into account height information by setting the reference plane, so that it is possible to omit the reflection visibility judgment on the vertical cross section mentioned above.

[Operation of the channel placement design assistance device]
An example of the operation of the station placement design support device 1 in the fourth embodiment will be described below. Note that in the operation of the station placement design support device 1 in the fourth embodiment, the operations other than step S6 in the flowchart shown in Fig. 2 are the same as the operations of the station placement design support device 1 in the first embodiment described above. Therefore, only the operation of narrowing down the combination candidate group by the visibility judgment based on the map information shown in step S6 in the flowchart in Fig. 4 will be described below.

Figure 31 is a flowchart showing an example of the operation of visibility determination processing by the map visibility determination unit 16 in the fourth embodiment of the present invention.

The map visibility determination unit 16 sets a reference plane, which is a horizontal plane at a predetermined height (step S631). For example, the map visibility determination unit 16 sets the horizontal plane at the height at which the base station b11 is installed on the utility pole p11 as the reference plane.

The map visibility determination unit 16 acquires information indicating the group of combination candidates, facility information, and map information stored in the memory unit 30. The map visibility determination unit 16 selects one combination candidate for which visibility has not yet been determined from the acquired group of combination candidates (step S632).

The map visibility determination unit 16 extracts reflective surfaces on the reference plane that have visibility from the candidate installation positions of the base station based on the selected combination candidates (step S633). The map visibility determination unit 16 also extracts reflective surfaces on the reference plane that have visibility from the candidate installation positions of the terminal station based on the selected combination candidates (step S634).

The map visibility determination unit 16 compares the reflective surfaces that are visible from the candidate installation positions of the base station extracted in step S633 with the reflective surfaces that are visible from the candidate installation positions of the terminal station extracted in step S634, and determines whether or not there are any reflective surfaces that are visible from both stations (step 635).

If the map visibility determination unit 16 determines as a result of the comparison that there is no reflective surface that is visible from both stations (step S635, NO), it deletes the selected combination candidate from the obtained group of combination candidates (step S636).

The map visibility determination unit 16 repeats the operations from step S632 to step S636 until it has performed a reflection visibility determination for all combination candidates included in the acquired combination candidate group (step S637). If the visibility determination has been performed for all combination candidates included in the acquired combination candidate group (step S637, YES), the process proceeds to step S7 in the flowchart shown in FIG. 2.

As described above, the station placement design support device 1 in the fourth embodiment of the present invention sets a reference plane that is a horizontal plane at a predetermined height and performs a reflection visibility judgment on the reference plane. As a result, the station placement design support device 1 can simply perform a reflection visibility judgment on the reference plane that is a horizontal plane, and simultaneously perform a simple reflection visibility judgment in the height direction, thereby omitting the processing of reflection visibility judgment on the vertical cross section described above.

The series of processes for determining visibility of reflections shown in the flowchart of Fig. 31 may be incorporated into the flowchart shown in Fig. 8 described above. In this case, it becomes possible to carry out the processes for determining direct visibility between the candidate installation locations of the base station and the candidate installation locations of the terminal station together with the series of processes for determining visibility of reflections shown in Fig. 31.

By having such a configuration, the station placement design support device 1 in the fourth embodiment of the present invention can appropriately present combination candidates while reducing the amount of calculation, particularly in determining reflection visibility in the vertical direction.

Fifth embodiment
In the fourth embodiment described above, the station location design support device 1 is configured to set a horizontal plane at a predetermined height, such as the height at which a base station is installed, as a reference plane and perform a reflection visibility judgment on the reference plane. Here, the lower the height of the reference plane, the more buildings that have walls that become reflection surfaces, and therefore the number of combination candidates narrowed down by the reflection visibility judgment is expected to be greater. The station location design support device 1 in the fifth embodiment described below adjusts the height of the reference plane so that the number of combination candidates narrowed down becomes a desired number.

Figures 32 to 35 are figures for explaining an example of visibility determination by the station placement design support device 1 of the fifth embodiment of the present invention.

Figure 32 shows utility pole p11, which is a candidate installation location for the base station, and base station b11 when installed on utility pole p11. Figure 32 also shows wall position h11-2, which is the position of the end of one wall of house h11, which is a candidate installation location for a terminal station, and terminal station t11 when installed at wall position h11-2. Figure 32 also shows houses h12 and h13, which may act as obstructions blocking the propagation of radio waves between base station b11 and terminal station t11.

Figure 32 also shows reference planes of three different heights. Reference plane rp11 is a horizontal plane at the height of the candidate installation location for base station b11. Reference plane rp12 is a horizontal plane at a lower height than the above-mentioned reference plane rp11. Reference plane rp13 is a horizontal plane at an even lower height than the above-mentioned reference plane rp12.

As shown in FIG. 32, the height of house h11 is higher than reference plane rp11. The height of house h12 is higher than reference plane rp12 and lower than reference plane rp11. The height of house h13 is higher than reference plane rp13 and lower than reference plane rp12. Note that wall position h11-2, which is a candidate installation position for terminal station t11, is lower than reference plane rp13.

Figure 33 shows how reflection visibility is determined when the reference plane rp11 is set. As shown in the figure, in the reference plane rp11, houses h12 and h13, which are lower in height than the reference plane rp11, are not recognized as buildings having walls that can serve as reflective surfaces. Therefore, when the reference plane rp11 is set, since there are no building walls that can serve as reflective surfaces, the map visibility determination unit 16 determines that this combination candidate has no reflection visibility.

Figure 34 shows how reflection visibility is determined when the reference plane rp12 is set. As shown in the figure, in the reference plane rp12, house h13, which is lower in height than the reference plane rp12, is not recognized as a building having a wall that can be a reflective surface. On the other hand, as shown in the figure, in the reference plane rp12, house h12, which is higher than the reference plane rp12, is recognized as a building that can have a wall that can be a reflective surface. However, based on the positional relationship between the utility pole p11, the wall position h11-2, and the house h12, the house h12 does not have a wall that can be a reflective surface candidate, so the map visibility determination unit 16 determines that this combination candidate has no reflection visibility.

Figure 35 shows how reflection visibility is determined when the reference plane rp13 is set. As shown in the figure, in the reference plane rp13, houses h12 and h13, which are taller than the reference plane rp13, are recognized as buildings that may have walls that may be candidates for reflection surfaces. However, due to the positional relationship between the utility pole p11, wall position h11-2, and house h12, house h12 does not have a wall that is a candidate for a reflection surface. On the other hand, due to the positional relationship between the utility pole p11, wall position h11-2, and house h13, house h13 has a wall that is a candidate for a reflection surface. As a result, the map visibility determination unit 16 determines that this combination candidate has reflection visibility.

In this way, the lower the height of the reference plane, the greater the number of combination candidates that are determined to have reflection visibility among the combination candidates. The station placement design support device 1 of this embodiment adjusts the height of the reference plane so that the number of combination candidates after reflection visibility determination becomes the desired number.

[Operation of the channel placement design assistance device]
An example of the operation of the station placement design support device 1 in the fifth embodiment will be described below. Note that in the operation of the station placement design support device 1 in the fifth embodiment, the operations other than step S6 in the flowchart shown in Fig. 2 are the same as the operations of the station placement design support device 1 in the first embodiment described above. Therefore, only the operation of narrowing down the combination candidate group by the visibility judgment based on the map information shown in step S6 in the flowchart in Fig. 5 will be described below.

Figure 36 is a flowchart showing an example of the operation of visibility determination processing by the map visibility determination unit 16 in the fifth embodiment of the present invention.

The map visibility determination unit 16 sets a reference plane that is a horizontal plane at a predetermined height (step S641). The map visibility determination unit 16 sets the highest reference plane among the reference planes at multiple heights. For example, the map visibility determination unit 16 sets the horizontal plane at the height at which the base station b11 is installed on the utility pole p11 as the reference plane.

The map visibility determination unit 16 acquires information indicating the group of combination candidates, facility information, and map information stored in the memory unit 30. The map visibility determination unit 16 selects one combination candidate for which visibility has not yet been determined from the acquired group of combination candidates (step S642).

The map visibility determination unit 16 extracts reflective surfaces on the reference plane that have visibility from the candidate installation positions of the base station based on the selected combination candidates (step S643). The map visibility determination unit 16 also extracts reflective surfaces on the reference plane that have visibility from the candidate installation positions of the terminal station based on the selected combination candidates (step S644).

The map visibility determination unit 16 compares the reflective surfaces that are visible from the candidate installation positions of the base station extracted in step S643 with the reflective surfaces that are visible from the candidate installation positions of the terminal station extracted in step S644, and determines whether or not there are any reflective surfaces that are visible from both stations (step 645).

If the map visibility determination unit 16 determines as a result of the comparison that there is no reflective surface that is visible from both stations (step S645, NO), it deletes the selected combination candidate from the obtained group of combination candidates (step S646).

The map visibility determination unit 16 repeats the operations from step S642 to step S646 described above until reflection visibility determination has been performed for all combination candidates included in the obtained group of combination candidates (step S647).

If visibility judgment has been performed on all combination candidates included in the acquired combination candidate group (step S647, YES), the map visibility judgment unit 16 counts the number of combination candidates included in the combination candidate group that have been narrowed down by the reflection visibility judgment. If the number of combination candidates included in the combination candidate group does not reach a predetermined number (step S648, NO), the map visibility judgment unit 16 deletes the combination candidate group that has been narrowed down by the reflection visibility judgment (step S649).

The map visibility determination unit 16 reloads the group of combination candidates stored in the memory unit 30 before the reflection visibility determination was performed (step S650). In other words, the map visibility determination unit 16 resets the group of combination candidates. The map visibility determination unit 16 resets the height of the reference surface to a height one level lower (step S651). At this time, the map visibility determination unit 16 considers that the visibility determination has not yet been performed again for all combination candidates stored in the memory unit 30. As a result, in the above step S642, all combination candidates become selection candidates again.

The map visibility determination unit 16 repeats the operations from step S642 to step S651 until the number of combination candidates included in the combination candidate group narrowed down by the reflection likelihood determination becomes equal to or greater than a predetermined number (step S648). If the number of combination candidates included in the combination candidate group becomes equal to or greater than a predetermined number (step S648, YES), the process proceeds to step S7 in the flowchart shown in FIG. 2.

As described above, the station placement design support device 1 in the fifth embodiment of the present invention sets a reference plane, which is a horizontal plane at a predetermined height, and performs a reflection visibility judgment on the reference plane. Then, if the number of combination candidates included in the combination candidate group narrowed down by the reflection visibility judgment does not reach a predetermined number, the station placement design support device 1 slightly lowers the height of the reference plane and performs reflection visibility judgment on the reference plane again. The station placement design support device 1 repeats the reflection visibility judgment on the reference plane while gradually lowering the height of the reference plane until the number of combination candidates included in the combination candidate group narrowed down by the reflection visibility judgment reaches or exceeds the predetermined number.

In this way, the station placement design support device 1 in the fifth embodiment of the present invention can obtain a combination candidate group consisting of a desired number of combination candidates. In addition, the station placement design support device 1 can simultaneously perform a simple reflection visibility determination in the height direction simply by performing a reflection visibility determination on the reference plane, which is a horizontal plane, and therefore can omit the process of reflection visibility determination on the vertical cross section described above.

The series of processes for determining visibility of reflections shown in the flowchart of Fig. 36 may be incorporated into the flowchart shown in Fig. 8 described above. In this case, it becomes possible to carry out the processes related to determining direct visibility between the candidate installation locations of the base station and the candidate installation locations of the terminal station together with the series of processes for determining visibility of reflections shown in Fig. 36.

By having such a configuration, the station placement design support device 1 in the fifth embodiment of the present invention can appropriately present combination candidates while reducing the amount of calculation, particularly in determining reflection visibility in the vertical direction.

In each of the above embodiments, millimeter wave radio has been shown as an example of wireless communication between the base station and the terminal station, but other types of communication besides millimeter wave wireless communication, such as terrestrial digital communication, communication using satellite radio waves, or communication using UHF (Ultra High Frequency), may also be used.

According to the above-described embodiment, the station placement design support device includes a generation unit, a first determination unit, a second determination unit, and an output unit. For example, the station placement design support device is station placement design support device 1 in the embodiment, the generation unit is combination candidate group generation unit 15 in the embodiment, the first determination unit is map visibility determination unit 16 in the embodiment, the second determination unit is point cloud visibility determination unit 23 in the embodiment, and the output unit is combination candidate group output unit 40 in the embodiment.

The generation unit generates a first combination candidate group, which is a set of combinations of candidate installation locations of a first wireless station and candidate installation locations of a second wireless station that communicates with the first wireless station in the evaluation target area. For example, the first wireless station is base station b11 in the embodiment, and the second wireless station is terminal station t11 in the embodiment, and the first combination candidate group is a combination candidate group stored in the memory unit 30 by the combination candidate group generation unit 15 in the embodiment.

The first determination unit determines, for each combination included in the first combination candidate group, whether there is line of sight between the candidate installation locations of the first wireless station and the candidate installation locations of the second wireless station, based on first environmental information including information indicating the planar positions and heights of objects that can block or reflect radio waves present in the evaluation target area. For example, the objects that can block or reflect radio waves are obstructions such as houses h11 to h18 in the embodiment, and the first environmental information is map information and facility information in the embodiment.

The second determination unit determines whether or not there is line of sight between the candidate installation positions of the first wireless station and the candidate installation positions of the second wireless station for each combination determined by the first determination unit to have line of sight based on second environmental information having a larger amount of information than the first environmental information. For example, the second environmental information is point cloud data in the embodiment.

The output unit outputs a second group of combination candidates, which is a set of combinations that are determined to have visibility by the second determination unit. For example, the second group of combination candidates is a group of combination candidates after narrowing down of combination candidates based on visibility determination by the map visibility determination unit 16 and visibility determination by the point cloud visibility determination unit 23 in the embodiment.

In addition, the first judgment unit may be configured to determine whether or not there is visibility by regarding the object as a columnar object having a height based on the above information.

The first environmental information may include information about the shape of the roof of the object. In this case, the first determination unit may determine whether or not there is visibility by taking into account the shape of the roof.

In addition, the first judgment unit may be configured to judge whether or not there is visibility, including reflection of radio waves by objects that can reflect the radio waves.

The first determination unit may determine whether or not there is visibility based on the shielding ratio of a Fresnel zone generated between the first wireless station and the second wireless station. For example, the Fresnel zone is Fresnel zone fz11 in the embodiment.

In addition, the first judgment unit may set a reference plane, which is a horizontal plane at a predetermined height, for the area to be evaluated and judge whether or not there is visibility based on the height of the reference plane and the height of the object.

In addition, the first judgment unit may set the height of the reference plane so that the number of combinations included in the second combination candidate group is greater than or equal to a predetermined number.

The station placement design support device 1 in each of the above-mentioned embodiments may be realized by a computer. In that case, a program for realizing this function may be recorded on a computer-readable recording medium, and the program recorded on the recording medium may be read into a computer system and executed to realize the function. The term "computer system" as used herein includes hardware such as an OS and peripheral devices. The term "computer-readable recording medium" refers to portable media such as flexible disks, optical magnetic disks, ROMs, and CD-ROMs, and storage devices such as hard disks built into a computer system. The term "computer-readable recording medium" may also include a medium that dynamically holds a program for a short period of time, such as a communication line when transmitting a program via a network such as the Internet or a communication line such as a telephone line, and a medium that holds a program for a certain period of time, such as a volatile memory inside a computer system that is a server or client in that case. The above program may be a program for realizing part of the above-mentioned functions, or may be a program that can realize the above-mentioned functions in combination with a program already recorded in the computer system, or may be a program that is realized using a programmable logic device such as an FPGA (Field Programmable Gate Array).

The above describes in detail an embodiment of the present invention with reference to the drawings, but the specific configuration is not limited to this embodiment and also includes designs that do not deviate from the gist of the present invention.

1...station placement design support device, 11...facility information acquisition unit, h11-1, h11-2...wall surface position, 12...base station candidate position extraction unit, 13...map information acquisition unit, 14...terminal station candidate position extraction unit, 15...combination candidate group generation unit, 16...map visibility determination unit, 21...point cloud data acquisition unit, 22...data matching unit, 23...point cloud visibility determination unit, 30...memory unit, 40...combination candidate group output unit, 800, 801...building, 810, 811, 812...house, 821, 826...utility pole, 830, 834...base station, 840, 844...terminal station, 850, 851...station, 900, 901...optical fiber

Claims (8)

a generation unit that generates a first combination candidate group, which is a set of combinations of a candidate installation location of a first wireless station and a candidate installation location of a second wireless station that communicates with the first wireless station, in an evaluation target area;
a first determination unit that determines, for each of the combinations included in the first combination candidate group, whether there is line of sight between the candidate installation positions of the first wireless station and the candidate installation positions of the second wireless station based on first environmental information including information indicating planar contours of buildings that are present in the evaluation target area and that can block or reflect radio waves and heights of the buildings;
a second determination unit that determines, for each combination for which it has been determined by the first determination unit that there is line of sight , whether or not there is line of sight between the candidate installation positions of the first wireless station and the candidate installation positions of the second wireless station, based on second environmental information that is data with a higher density than the first environmental information and that is point cloud data of objects that exist in the evaluation target area and that includes objects other than the buildings;
an output unit that outputs a second combination candidate group that is a set of combinations determined to have prospects by the second determination unit;
A station placement design support device comprising: The station placement design assistance device according to claim 1 , wherein the first determination unit determines whether or not the line of sight is available by regarding the building as a columnar object having the height. the first environmental information includes information regarding a shape of a roof of the building ;
The station placement design assistance device according to claim 1 , wherein the first determination unit determines whether or not the visibility exists by taking into account a shape of the roof. The station location design assistance device according to claim 1 , wherein the first determination unit determines the presence or absence of the line of sight including the reflection of the radio wave by a building that can reflect the radio wave. The station placement design assistance device according to claim 1 , wherein the first determination unit determines whether or not there is line of sight based on a shielding ratio of a Fresnel zone generated between the first wireless station and the second wireless station. 6. The station placement design support device according to claim 1, wherein the first determination unit sets a reference plane, which is a horizontal plane at a predetermined height, for the evaluation target area, and determines whether or not there is visibility based on a height of the reference plane and a height of the building . The station placement design assistance device according to claim 6 , wherein the first determination unit sets the height of the reference plane so that a number of combinations included in a second combination candidate group is equal to or greater than a predetermined number. a generating step of generating a first combination candidate group which is a set of combinations of a candidate installation location of a first wireless station and a candidate installation location of a second wireless station which communicates with the first wireless station in an evaluation target area;
a first determination step of determining, for each of the combinations included in the first combination candidate group, whether there is line of sight between the candidate installation positions of the first wireless station and the candidate installation positions of the second wireless station based on first environmental information including information indicating outlines on a plane of buildings that are present in the evaluation target area and that can block or reflect radio waves and heights of the buildings;
a second determination step of determining, for each combination determined in the first determination step that the line of sight exists, whether or not there is line of sight between the candidate installation positions of the first wireless station and the candidate installation positions of the second wireless station based on second environmental information, which is data with a higher density than the first environmental information and is point cloud data of objects including objects other than the buildings that exist in the evaluation target area;
an output step of outputting a second combination candidate group which is a set of combinations determined to have prospects in the second determination step;
The present invention relates to a station placement design support method.

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