Patent Publication Number: US-2023156483-A1

Title: Station placement support method, station placement support apparatus and station placement support program

Description:
TECHNICAL FIELD 
     The present invention relates to a station deployment support method, a station deployment support apparatus, and a station deployment support program. 
     BACKGROUND ART 
       FIG.  32    is a partially modified schematic view of, regarding TIP (Telecom Infra Project) that is a consortium working together to accelerate the openness of the specifications of the general communication network devices (main members: Facebook, Deutsche Telecom, Intel, NOKIA, etc.), a use case proposed by mmWave Networks as a reference (for example, see Non-Patent Literatures 1 to 3). The mmWave Networks is one of the project groups of TIP and is aiming at constructing a network that is inexpensive and faster than deploying an optical fiber, using millimeter-wave radio signals in an unlicensed band. 
     Referring to buildings, such as buildings  800  and  801  and houses  810 ,  811 , and  812 , illustrated in  FIG.  32   , each of terminal station apparatuses (hereinafter referred to as “terminal stations”)  840  to  844 , which are installed on wall surfaces of the respective buildings, and base station apparatuses (hereinafter referred to as “base stations”)  830  to  834 , which are installed on utility poles  821  to  826 , is an apparatus called mmWave DN (Distribution Node). 
     Each of the base stations  830  to  834  is connected to one of communication apparatuses provided in telephone exchange stations (Fiber PoP (Point of Presence))  850  and  851  by an optical fiber  900  or  901 . The communication apparatuses are connected to a communication network of a provider. The mmWave Link, that is, millimeter-wave wireless communication is performed between one of the terminal stations  840  to  844  and one of the base stations  830  to  834  (hereinafter also referred to as “between the two stations”). In  FIG.  32   , millimeter-wave wireless links are indicated by alternate long and short dash lines. 
     In a configuration in which the base stations  830  to  834  are installed on the utility poles  821  to  826 , the terminal stations  840  to  844  are installed on the wall surfaces of the buildings, and millimeter-wave wireless communication is performed between the two stations, the act of selecting candidate positions for installing the base stations  830  to  834  and the terminal stations  840  to  844  is referred to as station deployment design (hereinafter also referred to as “station deployment”). 
     CITATION LIST 
     Non-Patent Literature 
     
         
         Non-Patent Literature 1: Sean Kinney, “Telecom Infra Project focuses on millimeter wave for dense networks, Millimeter Wave Networks Project Group eyes 60 GHz band”, Image courtesy of the Telecom Infra Project, RCR Wireless News, Intelligence on all things wireless, Sep. 13, 2017, [searched Mar. 6, 2020], the website (URL: https://www.rcrwireless.com/20170913/carriers/telecom-infra-project-millimeter-wave-tag17) 
         Non-Patent Literature 2: Frederic Lardinois, “Facebook-backed Telecom Infra Project adds a new focus on millimeter wave tech for 5G”, [searched Mar. 6, 2020], the website (URL: https://techcrunch.com/2017/09/12/facebook-backed-telecom-infra-project-adds-a-new-focus-on-millimeter-wave-tech-for-5g/?renderMode=ie11) 
         Non-Patent Literature 3: Jamie Davies, “DT and Facebook TIP the scales for mmWave”, GLOTEL AWARDS 2019, telecoms.com, Sep. 12, 2017, [searched Mar. 6, 2020], the website (URL: http://telecoms.com/484622/dt-and-facebook-tip-the-scales-for-mmwave/) 
       
    
     SUMMARY OF THE INVENTION 
     Technical Problem 
     As a method of station deployment design, there is known a method that uses three-dimensional point group data obtained by capturing an image of a space. Such a method includes, for example, first driving a mobile object, such as a vehicle, having an MMS (Mobile Mapping System) mounted thereon along a road around a residential area as an evaluation target to acquire three-dimensional point group data, and then evaluating wireless communication between one of the base stations  830  to  834  and one of the terminal stations  840  to  844  utilizing the acquired point group data. As an evaluation means, there is known a means of determining three-dimensional visibility or a means of calculating the shield factor for a space between the two stations. The “shield factor” herein is an index indicating the degree of influence of an object, which is present between one of the base stations  830  to  834  and one of the terminal stations  840  to  844 , on the wireless communication, and may also be referred to as “transmissivity” from the opposite perspective. To implement such an evaluation means, it is necessary to prepare point group data on all evaluation targets in the space including the candidate positions of the base stations  830  to  834  and the terminal stations  840  to  844 . 
     However, even when a mobile object having an MMS mounted thereon has traveled extensively in advance in an area set as an evaluation target by an apparatus for supporting station deployment design, there are many places from which point group data has been partially difficult to obtain. Alternatively, when the range of the evaluation target contains no point group data at all, it is necessary to collect new point group data. However, when the mobile object has already traveled in the range of the evaluation target, it is often the case that only the point group data that has been already obtained through the travel is used. If station deployment design is performed with the apparatus based on such point group data with partially missing information, a processing result with low accuracy may be output. 
     For example, assume that even when there is an object in a space between the base station  830  and the terminal station  840 , point group data on the object has not been acquired. In such a case, even if an apparatus for supporting station deployment performs three-dimensional visibility determination or shield factor calculation for the space between the two stations utilizing the acquired point group data, the apparatus performs a process on the assumption that there is no shielding object between the two stations because there is no point group data on the space between the two stations. Consequently, the apparatus for supporting station deployment design may erroneously determine that the space is “visible” or erroneously calculate the shield factor as a “low shield factor” that is sufficient to perform wireless communication. Therefore, the reliability of the processing result may decrease, which in turn may prompt a user to perform erroneous determination, for example, install the terminal station  840  on a wall surface of an inappropriate building. 
     There is also a case where one of the base station  830  and the terminal station  840  is present in the range in which point group data has not been acquired or is not present in the range around the travel trajectory of a mobile object having an MMS mounted thereon. In such a case also, a three-dimensional visibility determination or shield factor calculation process may be influenced depending on the positional relationship among the base station  830 , the terminal station  840 , and the travel trajectory. Therefore, the reliability of the processing result may decrease, which in turn may prompt a user to perform erroneous determination. 
     In view of the foregoing circumstances, it is an object of the present invention to provide a technique that allows a user to perform appropriate station deployment design by improving the state of acquisition of point group data from a space between a candidate position for installing a base station and a candidate position for installing a terminal station. 
     Means for Solving the Problem 
     An aspect of the present invention is a station deployment support method including a positional relationship identification step of, based on travel trajectory data indicating a travel trajectory of a mobile object that measures an object present in a three-dimensional space within a predetermined measurable distance and acquires point group data indicating a position of the measured object in the three-dimensional space, the measurable distance, candidate base station position data indicating a candidate position for installing a base station apparatus, and candidate terminal station position data indicating a candidate position for installing a terminal station apparatus, generating base station positional relationship identification data indicating a positional relationship between the travel trajectory and a candidate base station position, and terminal station positional relationship identification data indicating a positional relationship between the travel trajectory and a candidate terminal station position; a measurable range identification step of generating measurable range data indicating a measurable range based on the travel trajectory data and the measurable distance; and a travel trajectory selection step of selecting at least one piece of travel trajectory data so that a proportion of the measurable range in a predetermined evaluation area satisfies a predetermined value. 
     In addition, an aspect of the present invention is a station deployment support apparatus including a positional relationship identification unit that, based on travel trajectory data indicating a travel trajectory of a mobile object that measures an object present in a three-dimensional space within a predetermined measurable distance and acquires point group data indicating a position of the measured object in the three-dimensional space, the measurable distance, candidate base station position data indicating a candidate position for installing a base station apparatus, and candidate terminal station position data indicating a candidate position for installing a terminal station apparatus, generates base station positional relationship identification data indicating a positional relationship between the travel trajectory and a candidate base station position, and terminal station positional relationship identification data indicating a positional relationship between the travel trajectory and a candidate terminal station position; a measurable range identification unit that generates measurable range data indicating a measurable range based on the travel trajectory data and the measurable distance; and a travel trajectory selection unit that selects at least one piece of travel trajectory data so that a proportion of the measurable range in a predetermined evaluation area satisfies a predetermined value. 
     In addition, an aspect of the present invention is a station deployment support program for causing a computer to execute a positional relationship identification step of, based on travel trajectory data indicating a travel trajectory of a mobile object that measures an object present in a three-dimensional space within a predetermined measurable distance and acquires point group data indicating a position of the measured object in the three-dimensional space, the measurable distance, candidate base station position data indicating a candidate position for installing a base station apparatus, and candidate terminal station position data indicating a candidate position for installing a terminal station apparatus, generating base station positional relationship identification data indicating a positional relationship between the travel trajectory and a candidate base station position, and terminal station positional relationship identification data indicating a positional relationship between the travel trajectory and a candidate terminal station position; a measurable range identification step of generating measurable range data indicating a measurable range based on the travel trajectory data and the measurable distance; and a travel trajectory selection step of selecting at least one piece of travel trajectory data so that a proportion of the measurable range in a predetermined evaluation area satisfies a predetermined value. 
     Effects of the Invention 
     The present invention allows a user to perform appropriate station deployment design by improving the state of acquisition of point group data from a space between a candidate position for installing a base station and a candidate position for installing a terminal station. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is a block diagram illustrating the configuration of a station deployment support apparatus of a first embodiment. 
         FIG.  2    is a flowchart illustrating a process flow of the station deployment support apparatus of the first embodiment. 
         FIG.  3    is a view for describing a process of the station deployment support apparatus of the first embodiment in two stages. 
         FIG.  4    is a block diagram illustrating the configuration of a point group data processing unit in a station deployment support apparatus of a second embodiment. 
         FIG.  5    is a view illustrating the configuration of the positional relationship among a travel trajectory, a candidate base station position, and a candidate terminal station position in the second embodiment. 
         FIG.  6    is a view illustrating the configuration of the positional relationship among a travel trajectory, a candidate base station position, and a candidate terminal station position in the second embodiment. 
         FIG.  7    is a view illustrating the configuration of the positional relationship among a travel trajectory, a candidate base station position, and a candidate terminal station position in the second embodiment. 
         FIG.  8    is a view illustrating the configuration of the positional relationship among a travel trajectory, a candidate base station position, and a candidate terminal station position in the second embodiment. 
         FIG.  9    is a view illustrating the configuration of the positional relationship among a travel trajectory, a candidate base station position, and a candidate terminal station position in the second embodiment. 
         FIG.  10    is a view illustrating the configuration of the positional relationship among a travel trajectory, a candidate base station position, and a candidate terminal station position in the second embodiment. 
         FIG.  11    is a view illustrating the configuration of the positional relationship among a travel trajectory, a candidate base station position, and a candidate terminal station position in the second embodiment. 
         FIG.  12    is a view illustrating the configuration of the positional relationship among a travel trajectory, a candidate base station position, and a candidate terminal station position in the second embodiment. 
         FIG.  13    is a view illustrating the configuration of the positional relationship among a travel trajectory, a candidate base station position, and a candidate terminal station position in the second embodiment. 
         FIG.  14    is a view illustrating the configuration of the positional relationship among a travel trajectory, a candidate base station position, and a candidate terminal station position in the second embodiment. 
         FIG.  15    is a flowchart illustrating a process flow of a point group data processing unit in the station deployment support apparatus of the second embodiment. 
         FIG.  16    is a view illustrating the positional relationship between an evaluation area and a travel trajectory in a third embodiment. 
         FIG.  17    is a view illustrating the positional relationship between the evaluation area and the travel trajectory in the third embodiment. 
         FIG.  18    is a view illustrating the positional relationship between the evaluation area and the travel trajectory in the third embodiment. 
         FIG.  19    is a view illustrating the positional relationship between the evaluation area and the travel trajectory in the third embodiment. 
         FIG.  20    is a chart illustrating the effect of superposition of travel trajectories with a station deployment support apparatus of the third embodiment. 
         FIG.  21    is a block diagram illustrating the configuration of a point group data processing unit in the station deployment support apparatus of the third embodiment. 
         FIG.  22    is a flowchart illustrating a process flow of the point group data processing unit in the station deployment support apparatus of the third embodiment. 
         FIG.  23    is a view illustrating the positional relationship between an evaluation area and a travel trajectory in a fourth embodiment. 
         FIG.  24    is an enlarged view illustrating the positional relationship between the evaluation area and the travel trajectory in the fourth embodiment. 
         FIG.  25    is a view illustrating the configuration of the positional relationship among a travel trajectory, a candidate base station position, a candidate terminal station position, and a truck in a fifth embodiment. 
         FIG.  26    is a graph illustrating an exemplary transition of the shield factor of a space between the candidate base station position and the candidate terminal station position in the fifth embodiment. 
         FIG.  27    is a flowchart illustrating a process flow of a station deployment support apparatus of the fifth embodiment. 
         FIG.  28    is a view illustrating the configuration of the positional relationship among a travel trajectory, a candidate base station position, a candidate terminal station position, and a tree in a sixth embodiment. 
         FIG.  29    is a view illustrating the configuration of the positional relationship among a travel trajectory, a candidate base station position, a candidate terminal station position, and a tree in the sixth embodiment. 
         FIG.  30    is a graph illustrating an exemplary transition of the shield factor of a space between the candidate base station position and the candidate terminal station position in the sixth embodiment. 
         FIG.  31    is a flowchart illustrating a process flow of a station deployment support apparatus of the sixth embodiment. 
         FIG.  32    is a view illustrating an example of a use case proposed by TIP. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     First Embodiment 
     Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.  FIG.  1    is a block diagram illustrating the configuration of a station deployment support apparatus  1  that is an apparatus for supporting station deployment design of the first embodiment. The station deployment support apparatus  1  includes a design area designation unit  2 , a candidate base station position extraction unit  3 , a candidate terminal station position extraction unit  4 , a two-dimensional visibility determination processing unit  5 , a point group data processing unit  6 , a number-of-stations calculation unit  7 , an operation processing unit  10 , a map data storage unit  11 , a facility data storage unit  12 , a point group data storage unit  13 , a travel trajectory data storage unit  14 , and a two-dimensional visibility determination result storage unit  15 . The point group data processing unit  6  includes a candidate three-dimensional position selection unit  20 , a positional relationship identification unit  21 , a confidence coefficient identification unit  22 , a three-dimensional visibility determination processing unit  23 , and a shield factor calculation unit  24 . 
     Described below is data stored in advance in the map data storage unit  11 , the facility data storage unit  12 , the point group data storage unit  13 , and the travel trajectory data storage unit  14  of the station deployment support apparatus  1 . 
     The map data storage unit  11  stores two-dimensional map data in advance. The map data includes, for example, data indicating the position and the shape of a candidate building in which a terminal station is to be installed, data indicating the range of the site of the building, and data indicating a road. The facility data storage unit  12  stores candidate base station position data on the two-dimensional coordinate system (hereinafter referred to as “candidate two-dimensional base station position data”) indicating a candidate base station installation building structure that is an outdoor facility, such as a utility pole, on which a base station is to be installed. 
     The point group data storage unit  13  stores three-dimensional point group data acquired by an MMS, for example. The travel trajectory data storage unit  14  stores in advance travel trajectory data indicating the travel trajectory of a mobile object, such as a vehicle, having an MMS mounted thereon, for example. Herein, the travel trajectory data is data represented by a two-dimensional line segment on the coordinate system of the map data, for example. 
     Hereinafter, the configuration of each functional unit of the station deployment support apparatus  1  as well as a process flow of a station deployment support method performed by the station deployment support apparatus  1  will be described with reference to a flowchart illustrated in  FIG.  2   . 
     The design area designation unit  2  reads the two-dimensional map data from the map data storage unit  11  (step S 1 - 1 ). The design area designation unit  2  writes and stores the read map data into a working memory, for example. The design area designation unit  2  selects a rectangular area on the map data stored in the working memory based on a designation signal designating the range of a design area output from the operation processing unit  10  in response to an operation of the user of the station deployment support apparatus  1 , for example. The design area designation unit  2  designates the selected area as a design area (step S 1 - 2 ). 
     The candidate terminal station position extraction unit  4  extracts, for each building, building contour data, which indicates the position and the shape of the building, from the map data within the design area (step S 2 - 1 ). The building contour data extracted by the candidate terminal station position extraction unit  4  is data indicating a wall surface of the building on which a terminal station may possibly be installed, and thus is regarded as a candidate position for installing a terminal station. 
     The candidate terminal station position extraction unit  4  generates building identification data, which is identification information capable of uniquely identifying each individual building, and provides the data to the extracted building contour data on each building. The candidate terminal station position extraction unit  4  associates the thus provided building identification data with the building contour data corresponding to the building, and outputs the resulting data. 
     The candidate base station position extraction unit  3  reads from the facility data storage unit  12  candidate two-dimensional base station position data corresponding to a base station installation building structure located in the design area designated by the design area designation unit  2 , and outputs the read data (step S 3 - 1 ). It should be noted that when the coordinates of the map data stored in the map data storage unit  11  do not coincide with the coordinates of the candidate two-dimensional base station position data stored in the facility data storage unit  12 , the candidate base station position extraction unit  3  converts the coordinates of the read candidate two-dimensional base station position data into the coordinate system of the map data. 
     The two-dimensional visibility determination processing unit  5  performs, for each piece of the candidate two-dimensional base station position data output from the candidate base station position extraction unit  3 , determination of whether each building is visible in the horizontal direction from the position indicated by each piece of the candidate two-dimensional base station position data, based on the building contour data on each building output from the candidate terminal station position extraction unit  4 , using a means disclosed in Reference 1 (Japanese Patent Application No. 2019-004727), for example. The two-dimensional visibility determination processing unit  5  detects as the visible range the range of the building that has been determined to be visible, that is, wall surfaces of the building (step S 4 - 1 ). 
     The two-dimensional visibility determination processing unit  5  further preferentially selects, from among the wall surfaces of the building corresponding to the detected visible range, a candidate wall surface of the building for installing a terminal station. When the visible range of a given building includes a plurality of wall surfaces, for example, the two-dimensional visibility determination processing unit  5  preferentially determines a wall surface closer to the base station as a wall surface for installing a terminal station, and selects such a wall surface as a final visible range in the horizontal direction. 
     It should be noted that when the visible range of a given building includes a plurality of wall surfaces, the method of selecting a wall surface is not limited to the aforementioned method and may be any method. For example, selection may be performed based on the value of a confidence coefficient described below. 
     The two-dimensional visibility determination processing unit  5  associates, for each candidate base station position, the building contour data on the building having the detected visible range in the horizontal direction with data indicating the visible range in the horizontal direction of the building, and writes and stores the resulting data into the two-dimensional visibility determination result storage unit  15  (step S 4 - 2 ). Accordingly, building identification data on a building as well as data indicating the visible range in the horizontal direction of the building corresponding to the building identification data is stored in the two-dimensional visibility determination result storage unit  15  for each piece of candidate two-dimensional base station position data. 
     The two-dimensional visibility determination processing unit  5  determines the presence or absence of an instruction signal, which indicates “an instruction to consider a building that has another building present between such building and the candidate base station position,” output from the operation processing unit  10  in response to an operation of the user of the station deployment support apparatus  1  (step S 4 - 3 ). It should be noted that the user of the station deployment support apparatus  1  has selected in advance whether to consider a building that has another building present between such building and the candidate base station position before the process in  FIG.  2    is started, and if the user has selected to consider such building, the operation processing unit  10  outputs an instruction signal indicating “an instruction to consider a building that has another building present between such building and the candidate base station position” in response to an operation of the user. 
     If the two-dimensional visibility determination processing unit  5  determines that such an instruction signal is not received (step S 4 - 3 , No), the process proceeds to step S 5 - 1 . Meanwhile, if the two-dimensional visibility determination processing unit  5  determines that such an instruction signal is received (step S 4 - 3 , Yes), the process proceeds to step S 4 - 4 . 
     The two-dimensional visibility determination processing unit  5  detects, for each piece of candidate two-dimensional base station position data, a building that has another building present between such building and the position indicated by the candidate two-dimensional base station position data, as a target building for which visibility in the vertical direction is to be detected, among buildings within the design area. For example, the two-dimensional visibility determination processing unit  5  refers to the two-dimensional visibility determination result storage unit  15 , and, for each piece of candidate two-dimensional base station position data, determines a building without the visible range detected in the horizontal direction as a building that has another building present such building and the position indicated by the candidate two-dimensional base station position data, and thus detects the building as a target building for which visibility in the vertical direction is to be detected (hereinafter, a target building for which visibility in the vertical direction is to be detected shall also be referred to as a “visibility-detection-target building”). 
     The two-dimensional visibility determination processing unit  5 , in response to an operation of the user of the station deployment support apparatus  1 , captures from the outside data indicating the installation altitude for each candidate base station position designated by the user as well as data indicating the height of each building, for example. 
     The two-dimensional visibility determination processing unit  5  performs, for each visibility-detection-target building for each detected candidate base station position, detection of the visible range in the vertical direction from the height of the installation altitude at the candidate base station position, using the captured data indicating the height of the building. The two-dimensional visibility determination processing unit  5  associates the building identification data on the building having the detected visible range in the vertical direction with data indicating the detected visible range in the vertical direction of the building, and writes and stores the resulting data into the two-dimensional visibility determination result storage unit  15  (step S 4 - 4 ). Accordingly, building identification data on a building as well as data indicating the visible range in the horizontal and vertical directions of the building corresponding to the building identification data is stored in the two-dimensional visibility determination result storage unit  15  for each piece of candidate two-dimensional base station position data. 
     The candidate three-dimensional position selection unit  20  in the point group data processing unit  6  selects a candidate base station position indicating a candidate position for installing a base station in a three-dimensional space, and a candidate terminal station position indicating a candidate position for installing a terminal station in the three-dimensional space. 
     For example, the user of the station deployment support apparatus  1  operates the operation processing unit  10  to select one piece of candidate two-dimensional base station position data from the two-dimensional visibility determination result storage unit  15 . The operation processing unit  10  outputs the selected candidate two-dimensional base station position data to the candidate three-dimensional position selection unit  20 . The candidate three-dimensional position selection unit  20  captures the candidate two-dimensional base station position data output from the operation processing unit  10 . The candidate three-dimensional position selection unit  20  acquires from the point group data storage unit  13  point group data around the position indicated by the captured candidate two-dimensional base station position data, and displays the acquired point group data on a screen. The user operates the operation processing unit  10  to select a candidate three-dimensional position for installing a base station from among the pieces of point group data displayed on the screen, and output the selected candidate three-dimensional position to the candidate three-dimensional position selection unit  20 . The candidate three-dimensional position selection unit  20  captures the three-dimensional position output from the operation processing unit  10 , and determines the captured three-dimensional position as the candidate three-dimensional base station position data. 
     Next, the candidate three-dimensional position selection unit  20  reads from the two-dimensional visibility determination result storage unit  15  data indicating the visible range of the building associated with the captured candidate two-dimensional base station position data. The candidate three-dimensional position selection unit  20  reads from the point group data storage unit  13  point group data in the range indicated by the read data indicating the visible range of the building, and displays the read point group data on the screen. The user operates the operation processing unit  10  to select a candidate three-dimensional position for installing a terminal station from among the pieces of point group data displayed on the screen, and output the selected candidate three-dimensional position to the candidate three-dimensional position selection unit  20 . The candidate three-dimensional position selection unit  20  captures the three-dimensional position output from the operation processing unit  10 , and determines the captured three-dimensional position as the candidate three-dimensional terminal station position data. Hereinafter, the candidate three-dimensional base station position data shall be simply referred to as “candidate base station position data,” and the candidate three-dimensional terminal station position data shall be simply referred to as “candidate terminal station position data.” 
     The positional relationship identification unit  21  performs, for each combination of the candidate base station position data and the candidate terminal station position data selected by the candidate three-dimensional position selection unit  20 , generation of base station positional relationship identification data indicating the positional relationship between the travel trajectory and the candidate base station position, and terminal station positional relationship identification data indicating the positional relationship between the travel trajectory and the candidate terminal station position based on the travel trajectory data stored in the travel trajectory data storage unit  14 . 
     The confidence coefficient identification unit  22  performs, based on the base station positional relationship identification data and the terminal station positional relationship identification data generated by the positional relationship identification unit  21 , identification of a confidence coefficient indicating the degree of reliability of the processing result of a predetermined evaluation process performed based on the point group data. Herein, the predetermined evaluation process is a three-dimensional visibility determination process performed by the three-dimensional visibility determination processing unit  23  or a shield factor calculation process performed by the shield factor calculation unit  24 . 
     The confidence coefficient identification unit  22  outputs the identified confidence coefficient together with a combination of the candidate base station position data and the candidate terminal station position data corresponding to the confidence coefficient (step S 5 - 1 ). The confidence coefficient identification unit  22  can, by presenting the confidence coefficient to the user of the station deployment support apparatus  1 , allow the user to recognize the degree of reliability of the processing result of a predetermined evaluation process for each combination of the candidate base station position and the candidate terminal station position. 
     The three-dimensional visibility determination processing unit  23  reads from the point group data storage unit  13  point group data of a space between the candidate base station position and the candidate terminal station position respectively indicated by the candidate base station position data and the candidate terminal station position data selected by the candidate three-dimensional position selection unit  20  (step S 5 - 2 ). Then, the three-dimensional visibility determination processing unit  23  performs a three-dimensional visibility determination process for the space between the candidate base station position and the candidate terminal station position based on the read point group data, using a means disclosed in Reference 2 (Japanese Patent Application No. 2019-001401), for example, and estimates if communication is possible based on the result of the determination process (step S 5 - 3 ). 
     In contrast, when the point group data processing unit  6  calculates the shield factor, the shield factor calculation unit  24  reads from the point group data storage unit  13  point group data of the space between the candidate base station position and the candidate terminal station position respectively indicated by the candidate base station position data and the candidate terminal station position data selected by the candidate three-dimensional position selection unit  20  (step S 5 - 2 ). Then, the shield factor calculation unit  24  calculates the shield factor of the space between the candidate base station position and the candidate terminal station position based on the read point group data, using a means disclosed in Reference 3 (Japanese Patent Application No. 2019-242831), for example, and estimates if communication is possible based on the result of the calculation process (step S 5 - 3 ). The point group data processing unit  6  performs the process of steps S 5 - 1  to S 5 - 3  for all combinations of the candidate base station position data and the candidate terminal station position data. 
     The number-of-stations calculation unit  7  counts the candidate base station positions and the candidate terminal station positions based on the result of estimation of if communication is possible, which has been performed by the point group data processing unit  6  using the three-dimensional point group data, and calculates the required number of base stations and the number of terminal stations to be accommodated for each candidate base station position (step S 6 - 1 ). 
     The configuration of the process performed by the station deployment support apparatus  1  can also be regarded as a two-stage process that includes a process performed using map data as two-dimensional data, and a process performed using point group data as three-dimensional data in response to the result of the first-stage process as illustrated in  FIG.  3   . 
     As illustrated in  FIG.  3   , the first-stage process performed using map data as two-dimensional data includes four processes: (1) designating a design area, (2) extracting a candidate terminal station position, (3) extracting a candidate base station position, and (4) determining visibility using the two-dimensional map data. 
     The process (1) of designating a design area corresponds to the process of steps S 1 - 1  and S 1 - 2  performed by the design area designation unit  2 . The process (2) of extracting a candidate terminal station position corresponds to the process of step S 2 - 1  performed by the candidate terminal station position extraction unit  4 . The process (3) of extracting a candidate base station position corresponds to the process of step S 3 - 1  performed by the candidate base station position extraction unit  3 . The process (4) of determining visibility using the two-dimensional map data corresponds to the process of steps S 4 - 1  to S 4 - 4  performed by the two-dimensional visibility determination processing unit  5 . 
     The second-stage process performed using point group data as three-dimensional data includes two processes: (5) determining if communication is possible using three-dimensional point group data, and (6) calculating the required number of base stations and the number of terminal stations to be accommodated in the design area. 
     The process (5) of determining if communication is possible using three-dimensional point group data corresponds to the process of steps S 5 - 1  to S 5 - 3  performed by the point group data processing unit  6 . The process (6) of calculating the required number of base stations and the number of terminal stations to be accommodated in the design area corresponds to the process of step S 6 - 1  performed by the number-of-stations calculation unit  7 . 
     For example, regarding a base station to be installed in an outdoor facility, such as a utility pole, and a terminal station to be installed on a wall surface of a building for performing millimeter-wave wireless communication, it is possible to support the station deployment design by determining the three-dimensional visibility of a space between a candidate base station position and a candidate terminal station position using three-dimensional point group data. To handle three-dimensional point group data, an enormous volume of data and enormous computer resources are needed. Therefore, the station deployment support apparatus  1  is configured such that before the three-dimensional point group data is utilized, the two-dimensional visibility determination processing unit  5  determines the two-dimensional visibility of a space between a candidate base station position and a candidate terminal station position, and the point group data processing unit  6  narrows the point group data to be utilized using the result of the determination so as to perform a three-dimensional visibility determination process. Therefore, it is possible to perform an efficient three-dimensional visibility determination process with reduced computer resources. 
     For wireless communication, it is important to not only determine simple linear visibility, but also calculate the “shield factor” of a spheroidal region, that is, a so-called Fresnel zone between transmission and reception related to the propagation of radio waves through a space. The point group data processing unit  6  in the station deployment support apparatus  1  includes the shield factor calculation unit  24  to calculate the shield factor. For calculation of the shield factor, more computer resources are needed than those for a three-dimensional visibility determination process. However, since the point group data to be utilized has been sufficiently narrowed through the two-dimensional visibility determination process performed by the two-dimensional visibility determination processing unit  5  in the station deployment support apparatus  1 , it is possible to perform an efficient shield factor calculation process with reduced computer resources. 
     In the station deployment support apparatus  1  of the first embodiment, the positional relationship identification unit  21  performs, based on travel trajectory data indicating the travel trajectory of a mobile object that travels and measures an object present in a three-dimensional space within a predetermined measurable distance, and then acquires point group data indicating the position of the measured object in the three-dimensional space, the measurable distance, candidate base station position data indicating a candidate position for installing a base station apparatus, and candidate terminal station position data indicating a candidate position for installing a terminal station apparatus, generation of base station positional relationship identification data that indicates the positional relationship between the travel trajectory and the candidate base station position, and terminal station positional relationship identification data that indicates the positional relationship between the travel trajectory and the candidate terminal station position. The confidence coefficient identification unit  22  is configured to, based on the base station positional relationship identification data and the terminal station positional relationship identification data generated by the positional relationship identification unit  21 , identify a confidence coefficient indicating the degree of reliability of the processing result of a predetermined evaluation process performed based on the point group data. 
     Accordingly, the confidence coefficient identification unit  22  can present to the user the confidence coefficient indicating the degree of reliability of the processing result of a predetermined evaluation process performed based on the point group data, for each candidate base station position and each candidate terminal station position. Therefore, when not all pieces of point group data have been acquired from the space between the candidate base station position and the candidate terminal station position, the reliability of the point group data is low, and in such a case, it is possible to allow the user to recognize from the confidence coefficient that the reliability of the processing result of a predetermined evaluation process performed using such point group data is also low. 
     For example, suppose that not all pieces of point group data have been acquired, but the three-dimensional visibility determination processing unit  23  indicates “visible” as a result of a determination process or the shield factor calculation unit  24  indicates “a sufficiently low shield factor that meets the requirement for wireless communication” as a result of a calculation process. Even in such a case, it is possible to urge the user to take precautions by presenting a confidence coefficient with a small value. Accordingly, it is possible to prevent the user from making erroneous determination, for example, selecting candidate positions for installing a base station and a terminal station in a space from which point group data, which serves as a basis for three-dimensional visibility determination or shield factor calculation, has not been acquired. 
     In addition, identifying the confidence coefficient can prompt the user to make the following determination depending on whether the value of the confidence coefficient is large or small. For example, suppose that not all pieces of point group data have been acquired from the space between the candidate base station position and the candidate terminal station position, but the value of the confidence coefficient is large. In such a case, it is possible to prompt the user to, regarding the combination of the candidate base station position and the candidate terminal station position to be considered, determine that consideration using the acquired point group data is possible. 
     Further, identifying the confidence coefficient can also allow the three-dimensional visibility determination processing unit  23  to determine whether to perform a three-dimensional visibility determination process or allow the shield factor calculation unit  24  to determine whether to calculate the shield factor depending on whether the value of the confidence coefficient is large or small. For example, the three-dimensional visibility determination processing unit  23  or the shield factor calculation unit  24  may be configured to, when the value of the confidence coefficient is small, not perform a process for a combination of the candidate base station position and the candidate terminal station position as the processing targets, so that the amount of calculation can be reduced. Further, when the user is notified of the fact that the three-dimensional visibility determination processing unit  23  or the shield factor calculation unit  24  has not performed a process, the user can be prompted to acquire point group data again from the space between the candidate base station position and the candidate terminal station position as the processing targets or reconsider the candidate base station position and the candidate terminal station position. Therefore, even when the state of acquisition of point group data from the space between the candidate base station position and the candidate terminal station position is not good, the user can perform appropriate station deployment design. 
     Second Embodiment 
     Hereinafter, a second embodiment of the present invention will be described with reference to the drawings. 
       FIG.  4    is a block diagram illustrating the internal configuration of a point group data processing unit  6   a  applied to the second embodiment. In the second embodiment, components identical to those of the first embodiment are denoted by identical reference signs. In the following description, a station deployment support apparatus of the second embodiment shall be referred to as a station deployment support apparatus  1   a  with a reference sign “ 1   a ” added thereto, though not illustrated in the drawings. The station deployment support apparatus  1   a  has a configuration obtained by replacing the point group data processing unit  6  in the station deployment support apparatus  1  of the first embodiment with the point group data processing unit  6   a  illustrated in  FIG.  4   . 
     First, the relevance of a confidence coefficient identified in the second embodiment to the positional relationship among the travel trajectory of a mobile object, such as a vehicle, having an MMS mounted thereon, a candidate base station position, and a candidate terminal station position will be described with reference to  FIGS.  5  to  14   . 
     In  FIG.  5   , an arrowed line segment indicated by reference sign  50  is the travel trajectory indicated by the travel trajectory data stored in the travel trajectory data storage unit  14 , and indicates that a mobile object, such as a vehicle, having an MMS mounted thereon has traveled in the direction of the arrow. The MMS irradiates a surrounding space with a laser radar beam to measure the reflection of the laser radar beam from the object, and then records data on the direction in which the object is present as well as the distance from the object. Point group data is generated through the operation of converting the recorded data on the direction and the distance into the coordinates of the three-dimensional space. Herein, there is a limitation on the distance within which data on the direction and the distance can be obtained with a laser radar beam emitted from the MMS, and such a limitation is referred to as a measurable distance. The measurable distance is the distance determined by the performance of the MMS and is a known value. 
     A planar region indicated by reference sign  110  is a region indicating the measurable range of a laser radar beam emitted from the MMS for measurement purposes, and is a region having, on the opposite sides of the line segment of the travel trajectory  50  as the center, areas each corresponding to the length of the measurable distance of the MMS. Hereinafter, such a region shall be referred to as a measurable range  110 . 
     In  FIG.  5   , a candidate base station position  60  indicated by candidate base station position data and a candidate terminal station position  70  indicated by candidate terminal station position data are located on the opposite sides of the travel trajectory  50 , and both the candidate base station position  60  and the candidate terminal station position  70  are included in a space obtained by expanding the measurable range  110  in the vertical direction. In other words, both the candidate base station position  60  on the two-dimensional plane for which the vertical coordinate components are ignored and the candidate terminal station position  70  on the two-dimensional plane for which the vertical coordinate components are ignored are located within the measurable range  110 . 
     It should be noted that in practice, a space in a sphere that has the MMS as the center and has the measurable distance as the radius corresponds to the measurable range. In addition, regarding an MMS that moves straight, a space in a cylinder that has the travel trajectory  50  as the center and has the measurable distance as the radius corresponds to the measurable range. However, usually, any of such measurable ranges has a measurable distance with a sufficiently large value in the horizontal direction in comparison with the altitude at which a base station apparatus is installed (on a utility pole, for example) and the altitude at which a terminal station apparatus is installed (on a wall surface of a building). Therefore, when the candidate base station position  60  and the candidate terminal station position  70  on the two-dimensional plane for which the vertical coordinate components are ignored are located within the measurable range  110 , it follows that the candidate base station position  60  and the candidate terminal station position  70  are also located within the measurable range in the three-dimensional space. 
     Hereinafter, the fact that the candidate base station position  60  or the candidate terminal station position  70  is included in the space obtained by expanding the measurable range  110  in the vertical direction is referred to as follows: “the candidate base station position  60  or the candidate terminal station position  70  is located within the measurable range  110 .” In contrast, the fact that the candidate base station position  60  or the candidate terminal station position  70  is not included in the space obtained by expanding the measurable range  110  in the vertical direction is referred to as follows: “the candidate base station position  60  or the candidate terminal station position  70  is located outside the measurable range  110 .” 
     A spheroid indicated by reference sign  80  is a Fresnel zone representing a region in which radio waves propagate. The Fresnel zone is formed when a wireless communication device is installed at each of the candidate base station position  60  and the candidate terminal station position  70 . When there is any point group data in the Fresnel zone  80 , it is highly probable that such a zone is determined to be not visible. In addition, the shield factor becomes high. 
       FIG.  6    is a view obtained by adding a planar region indicated by reference sign  100  to  FIG.  5   . The planar region indicated by reference sign  100  is a region having, on the opposite sides of the line segment of the travel trajectory  50  as the center, areas each corresponding to the length of the neighbor distance determined in advance that is shorter than the measurable distance of the MMS determined in advance. Hereinafter, such a region shall be referred to as a neighboring range  100 . For example, the neighbor distance may be determined in advance as a length corresponding to about half the width of a road in the evaluation target range on which a mobile object, such as a vehicle, having an MMS mounted thereon travels. 
     As illustrated in  FIG.  6   , the candidate base station position  60  is included in a space obtained by expanding the neighboring range  100  in the vertical direction. In contrast, the candidate terminal station position  70  is not included in the space obtained by expanding the neighboring range  100  in the vertical direction. In other words, the candidate base station position  60  on the two-dimensional plane for which the vertical coordinate components are ignored is located within the neighboring range  100 . Meanwhile, the candidate terminal station position  70  on the two-dimensional plane for which the vertical coordinate components are ignored is located outside the neighboring range  100 . 
     Hereinafter, the fact that the candidate base station position  60  or the candidate terminal station position  70  is included in the space obtained by expanding the neighboring range  100  in the vertical direction is referred to as follows: “the candidate base station position  60  or the candidate terminal station position  70  is located within the neighboring range  100 .” In contrast, the fact that the candidate base station position  60  or the candidate terminal station position  70  is not included in the space obtained by expanding the neighboring range  100  in the vertical direction is referred to as follows: “the candidate base station position  60  or the candidate terminal station position  70  is located outside the neighboring range  100 .” 
     As illustrated in  FIG.  6   , a case where both the candidate base station position  60  and the candidate terminal station position  70  are located within the measurable range  110  shall be hereinafter referred to as a “case a,” and the positional relationship of the “case a” shall be hereinafter referred to as a positional relationship configuration  200   a.    
     In the “case a,” both the candidate base station position  60  and the candidate terminal station position  70  are located within the measurable range  110 . Therefore, it is considered that all pieces of point group data in the space between the candidate base station position  60  and the candidate terminal station position  70  can be acquired unless some are missed during the measurement process. Therefore, it is estimated that the processing result of a three-dimensional visibility determination process of the three-dimensional visibility determination processing unit  23  and the processing result of a shield factor calculation process of the shield factor calculation unit  24 , each performed based on the acquired point group data, are high reliable. Thus, it is considered that it makes sense to perform such a process with the three-dimensional visibility determination processing unit  23  or the shield factor calculation unit  24 . 
     In a “case b” indicated by a positional relationship configuration  200   b  illustrated in  FIG.  7   , the candidate base station position  60  is located within the measurable range  110  and the neighboring range  100 , while the candidate terminal station position  70  is located outside the measurable range  110 . In this manner, when one of the candidate base station position  60  and the candidate terminal station position  70  is located outside the measurable range  110 , some pieces of point group data in the space between the two wireless stations cannot be acquired. In such a case, it is estimated that the processing result of a three-dimensional visibility determination process or the processing result of a shield factor calculation process is less reliable than in the “case a.” 
     However, even in the “case b,” when the processing result of a three-dimensional visibility determination process performed by the three-dimensional visibility determination processing unit  23  based on the acquired point group data indicates “not visible” or when the processing result of a shield factor calculation process performed by the shield factor calculation unit  24  based on the acquired point group data indicates a “high shield factor,” such a result actually serves as reference information for the user to determine that the propagation environment is not better than the obtained result. Therefore, although there is a need to warn the user about low reliability, it is considered that it makes some sense to perform the aforementioned process with the three-dimensional visibility determination processing unit  23  or the shield factor calculation unit  24 . 
     In a “case c” of a positional relationship configuration  200   c  illustrated in  FIG.  8   , both the candidate base station position  60  and the candidate terminal station position  70  are located outside the measurable range  110 . In such a case, it is impossible to acquire point group data from the space between the candidate base station position  60  and the candidate terminal station position  70 . Therefore, it is nonsense to perform a three-dimensional visibility determination process of the three-dimensional visibility determination processing unit  23  or a shield factor calculation process of the shield factor calculation unit  24  that should be performed based on point group data. Even if such a process is performed, it is estimated that the obtained processing result has quite low reliability. Therefore, in the “case c,” it is considered desirable not to perform a process with the three-dimensional visibility determination processing unit  23  or the shield factor calculation unit  24  and to present to the user information indicating “process impossible” such as “visibility determination impossible” or “shield factor calculation impossible.” 
     As described with reference to the three cases of the “case a” to the “case c” illustrated in  FIGS.  6  to  8   , the state of acquisition of point group data, which is present in the space between the candidate base station position  60  and the candidate terminal station position  70 , differs from case to case. Thus, the reliability of the acquired point group data also differs from case to case. In this manner, since point group data with difference reliability is utilized, the reliability of the processing result of a three-dimensional visibility determination process or a shield factor calculation process for the space between the candidate base station position  60  and the candidate terminal station position  70  also differs depending on the reliability of the point group data. 
     Therefore, when the degree of reliability of the pressing result of a predetermined evaluation process performed based on the acquired point group data is presented to the user of the station deployment support apparatus  1   a  in an easily understandable way using a confidence coefficient, the processing result of the predetermined evaluation process can be actually utilized for installing a base station and a terminal station if the confidence coefficient has a large value, for example. In contrast, if the confidence coefficient has a small value, it is possible to prompt the user to acquire point group data again or reconsider the positions of the candidate base station position  60  and the candidate terminal station position  70 . 
     The reliability of point group data is determined by the positional relationship among the candidate base station position  60 , the candidate terminal station position  70 , and the travel trajectory  50 .  FIG.  9    illustrates a case where the reliability of point group data is different other than the three cases illustrated in  FIGS.  6  to  8   . 
       FIG.  9    is a view representing a map of an urban area. A region of a road  400  is illustrated in a lattice pattern. Each of a plurality of regions partitioned in a lattice pattern by the regions of the road  400  is a site  300 . Each site  300  includes a plurality of buildings  310  indicated by a rectangular shape. 
       FIG.  9    also illustrates the travel trajectory  50  of a mobile object, such as a vehicle, having an MMS mounted thereon, and the neighboring range  100  and the measurable range  110  are illustrated along the travel trajectory  50 . As seen in  FIG.  9   , the measurable range  110  does not cover the entire urban area. 
       FIG.  9    also illustrates the “case a” represented by the positional relationship configuration  200   a  illustrated in  FIG.  6   , the “case b” represented by the positional relationship configuration  200   b  illustrated in  FIG.  7   , and the “case c” represented by the positional relationship configuration  200   c  illustrated in  FIG.  8   .  FIG.  9    further illustrates, in addition to such three cases, a “case d” represented by a positional relationship configuration  200   d , a “case e” represented by a positional relationship configuration  200   e , and a “case f” represented by a positional relationship configuration  200   f.    
     In the “case d,” both the candidate base station position  60  and the candidate terminal station position  70  are located within the measurable range  110 , and the candidate base station position  60  is further located within the neighboring range  100 . When the “case d” and the “case a” are compared, the “case d” differs from the “case a” in that the candidate base station position  60  indicated by a solid circle “●” and the candidate terminal station position  70  indicated by a hollow circle “∘” that are included in the positional relationship configuration  200   d  are present on one side of the travel trajectory  50 . 
     In the “case e,” both the candidate base station position  60  indicated by a solid circle “●” and the candidate terminal station position  70  indicated by a hollow circle “∘” that are included in the positional relationship configuration  200   e  are located within the neighboring range  100 . Therefore, the Fresnel zone  80  is also located within the neighboring range  100 . Thus, in the “case e,” it is considered that point group data with further higher reliability than that in the “case a” can be acquired. Thus, in the “case e,” it can be estimated that the processing result of a three-dimensional visibility determination process of the three-dimensional visibility determination processing unit  23  and the processing result of a shield factor calculation process of the shield factor calculation unit  24 , each performed based on the acquired point group data, have further higher reliability than in the “case a.” 
     In the “case f,” both the candidate base station position  60  indicated by a solid circle “●” and the candidate terminal station position  70  indicated by a hollow circle “∘” that are included in the positional relationship configuration  200   f  are located within the neighboring range  100  as in the “case e.” However, the “case f” differs from the “case e” in that a part of the Fresnel zone  80  is located neither within the neighboring range  100  nor within the measurable range  110 . Therefore, in the “case f,” it is considered that the reliability of the point group data that can be acquired is lower than that in the “case e.” Thus, in the “case f,” it can be estimated that the processing result of a three-dimensional visibility determination process of the three-dimensional visibility determination processing unit  23  and the processing result of a shield factor calculation process of the shield factor calculation unit  24 , each performed based on the acquired point group data, is less reliable than in the “case e.” 
     Next, referring to  FIG.  10   , further consideration of the reliability of point group data will be described using the “case b” and the “case d.”  FIG.  10    is an enlarged view of a region including the positional relationship configuration  200   a , the positional relationship configuration  200   b , and the positional relationship configuration  200   d  in  FIG.  9   . It should be noted that  FIG.  10    illustrates not only the enlarged view of  FIG.  9    but also trees  320   a - 1  to  320   a - 3 , a signboard  330   b , and the like that are omitted in  FIG.  9   . 
     It should be noted that in  FIGS.  10  to  12   , to illustrate the candidate base station position  60 , the candidate terminal station position  70 , and the Fresnel zone  80  for each case, reference signs “b” and “d” of the “case b” and the “case d” are added to their reference signs. In addition, to distinguish among the sites  300  and the buildings  310 , different alphabetical characters or branch numbers are added thereto for convenience&#39;s sake. 
     As described above, in the “case b,” the candidate base station position  60   b  is located within the measurable range  110  and the neighboring range  100 . The candidate terminal station position  70   b  is located on a wall surface of a building  310   b - 1  in a site  300   b , and such a position is outside the measurable range  110 . Point group data has not been acquired outside the measurable range  110 . As illustrated in  FIG.  10   , the signboard  330   b , which has a shop name and the like printed thereon, is present near the candidate terminal station position  70   b  and at a position shielding the Fresnel zone  80   b . Since the signboard  330   b  is not located within the measurable range  110 , point group data on the signboard  330   b  has not been acquired. 
       FIG.  11    illustrates a plan view of a region including the positional relationship configuration  200   b  illustrated in  FIG.  10   , and a bird&#39;s-eye view illustrating the region three-dimensionally. In the plan view and the bird&#39;s-eye view, corresponding objects, positions, and the like are denoted by identical reference signs. As seen in  FIG.  11   , the signboard  330   b  is located at a position shielding the Fresnel zone  80   b  and at a position outside the measurable range  110 . In such a case, the acquired point group data does not include the point group data on the signboard  330   b . Thus, in a three-dimensional visibility determination process performed by the three-dimensional visibility determination processing unit  23 , erroneous determination of “being visible” may be made. In addition, in a shield factor calculation process performed by the shield factor calculation unit  24 , a “low shield factor” may be obtained. In such a case, the user of the station deployment support apparatus  1   a  may make erroneous determination. 
     Meanwhile, suppose that a processing result of “being not visible” is obtained in a three-dimensional visibility determination process performed by the three-dimensional visibility determination processing unit  23  based on the acquired point group data or a processing result of a “high shield factor” is obtained in a shield factor calculation process performed by the shield factor calculation unit  24  based on the acquired point group data. In such a case, it can be said that the obtained processing result is a correct processing result. In this regard, even in the “case b,” it can be said that the processing result of a three-dimensional visibility determination process and the processing result of a shield factor calculation process have passable reliability. 
     In the “case d” represented by the positional relationship configuration  200   d  illustrated in  FIG.  10   , the candidate terminal station position  70   d  is located on a wall surface of a building  310   a - 1 , and a site  300   a  of the building  310   a - 1  is planted with trees  320   a - 1 ,  320   a - 2 , and  320   a - 3 , such as roadside trees or garden trees. Among them, the tree  320   a - 3  is located at a position shielding the Fresnel zone  80   d  between the candidate base station position  60   d  and the candidate terminal station position  70   d.    
       FIG.  12    illustrates a plan view of a region including the positional relationship configuration  200   d  illustrated in  FIG.  10   , and a bird&#39;s-eye view illustrating the region three-dimensionally. In the plan view and the bird&#39;s-eye view, corresponding objects, positions, and the like are denoted by identical reference signs. As seen in  FIG.  12   , the tree  320   a - 3  is located at a position shielding the Fresnel zone  80   d  and within the measurable range  110 . Since the tree  320   a - 3  is located within the measurable range  110 , point group data thereon has been acquired. 
     Typically, point group data on a tree, in particular, point group data on portions of branches and leaves of a tree include many gaps. For example, the thickness of leaves is about several [mm], while the interval of acquisition of point group data when a tree is not near the travel trajectory  50  is several [cm] to several tens of [cm], for example. Therefore, the acquired point group data on the tree includes many gaps depending on the density of branches and leaves of the tree. 
     When the three-dimensional visibility determination processing unit  23  performs a three-dimensional visibility determination process based on point group data including many gaps, a processing result of “being visible” may be obtained. In addition, when the shield factor calculation unit  24  performs a shield factor calculation process based on point group data including many gaps, a processing result of a “low shield factor” may be obtained. In such cases, the user of the station deployment support apparatus  1   a  may make erroneous determination. 
     Meanwhile, suppose that a processing result of “being not visible” is obtained in a three-dimensional visibility determination process performed by the three-dimensional visibility determination processing unit  23  based on the acquired point group data, or a processing result of a “high shield factor” is obtained in a shield factor calculation process performed by the shield factor calculation unit  24  based on the acquired point group data. In such a case, it can be said that the obtained processing result is a correct processing result. In this regard, even in the “case d,” it can be said that the processing result of a three-dimensional visibility determination process and the processing result of a shield factor calculation process have passable reliability. 
     Herein, referring again to  FIG.  4   , the configuration of the point group data processing unit  6   a  of the second embodiment will be described. The point group data processing unit  6   a  includes the candidate three-dimensional position selection unit  20 , the positional relationship identification unit  21   a , the confidence coefficient identification unit  22   a , the three-dimensional visibility determination processing unit  23 , the shield factor calculation unit  24 , a storage unit  25 , a connecting line segment identification unit  26 , and a measurable range proportion calculation unit  28 . 
     The positional relationship identification unit  21   a  includes a measurable range identification unit  30 , a measurable range presence determination unit  31 , a neighboring range identification unit  32 , a neighboring range presence determination unit  33 , and a determination result storage unit  34 . In the positional relationship identification unit  21   a , the measurable range identification unit  30  generates measurable range data indicating the measurable range  110  based on the travel trajectory data stored in the travel trajectory data storage unit  14  and the measurable distance determined in advance. 
     The measurable range presence determination unit  31  determines if the candidate base station position  60  is present within the measurable range  110  based on the measurable range data generated by the measurable range identification unit  30  and the candidate base station position data selected by the candidate three-dimensional position selection unit  20 . Then, the measurable range presence determination unit  31  generates base station positional relationship identification data indicating the determination result. The base station positional relationship identification data includes information indicating that the candidate base station position  60  is present within the measurable range  110  or information indicating that the candidate base station position  60  is present outside the measurable range  110 . Then, the measurable range presence determination unit  31  writes and stores the thus generated base station positional relationship identification data into the determination result storage unit  34 . 
     In addition, the measurable range presence determination unit  31  determines if the candidate terminal station position  70  is present within the measurable range  110  based on the measurable range data generated by the measurable range identification unit  30  and the candidate terminal station position data selected by the candidate three-dimensional position selection unit  20 . Then, the measurable range presence determination unit  31  generates terminal station positional relationship identification data indicating the determination result. The terminal station positional relationship identification data includes information indicating that the candidate terminal station position  70  is present within the measurable range  110  or information indicating that the candidate terminal station position  70  is present outside the measurable range  110 . Then, the measurable range presence determination unit  31  writes and stores the thus generated terminal station positional relationship identification data into the determination result storage unit  34 . 
     The neighboring range identification unit  32  generates neighboring range data indicating the neighboring range  100  based on the travel trajectory data stored in the travel trajectory data storage unit  14  and the neighbor distance determined in advance. The neighboring range presence determination unit  33  determines if the candidate base station position  60  is present within the neighboring range  100  based on the neighboring range data generated by the neighboring range identification unit  32  and the candidate base station position data selected by the candidate three-dimensional position selection unit  20 . Then, the neighboring range presence determination unit  33  adds information indicating the determination result to the base station positional relationship identification data. That is, the neighboring range presence determination unit  33  adds to the base station positional relationship identification data stored in the determination result storage unit  34  information indicating that the candidate base station position  60  is present within the neighboring range  100  or information indicating that the candidate base station position  60  is present outside the neighboring range  100 . 
     In addition, the neighboring range presence determination unit  33  determines if the candidate terminal station position  70  is present within the neighboring range  100  based on the neighboring range data generated by the neighboring range identification unit  32  and the candidate terminal station position data selected by the candidate three-dimensional position selection unit  20 . Then, the neighboring range presence determination unit  33  adds information indicating the determination result to the terminal station positional relationship identification data. That is, the neighboring range presence determination unit  33  adds to the terminal station positional relationship identification data stored in the determination result storage unit  34  information indicating that the candidate terminal station position  70  is present within the neighboring range  100  or information indicating that the candidate terminal station position  70  is present outside the neighboring range  100 . 
     The storage unit  25  stores a confidence coefficient calculation logic in advance. The confidence coefficient calculation logic is information for the confidence coefficient identification unit  22   a  to calculate and identify a confidence coefficient indicating the degree of reliability of the processing result of a predetermined evaluation process performed based on point group data. The predetermined evaluation process is, as described above, a three-dimensional visibility determination process performed by the three-dimensional visibility determination processing unit  23  or a shield factor calculation process performed by the shield factor calculation unit  24 . 
     The confidence coefficient identification unit  22   a  identifies a confidence coefficient indicating the degree of reliability of the processing result of a predetermined evaluation process performed based on point group data, based on the base station positional relationship identification data and the terminal station positional relationship identification data stored in the determination result storage unit  34  and the confidence coefficient calculation logic stored in the storage unit  25 . 
     Herein, regarding a case where a connecting line segment  90  crosses the travel trajectory  50 , the relationship between the proportion of the connecting line segment  90  included in the measurable range  110  and the reliability of point group data will be described through comparison between the “case a” of the positional relationship configuration  200   a  illustrated in  FIG.  13    and the “case b” of the positional relationship configuration  200   b  illustrated in  FIG.  14   . In  FIGS.  13  and  14   , the point of intersection between the connecting line segment  90  and the travel trajectory  50  is indicated by an intersection point  150 . As illustrated in  FIG.  13   , in the “case a,” the connecting line segment  90  connecting the candidate base station position  60  and the candidate terminal station position  70  is located within the measurable range  110  entirely, that is, at a proportion of 100[%]. 
     In contrast, in the “case b” of the positional relationship configuration  200   b  illustrated in  FIG.  14   , the candidate base station position  60  is located within the neighboring range  100 , while the candidate terminal station position  70  is located outside the measurable range  110  as described with reference to  FIG.  7   . In the “case b,” the candidate base station position  60  is located on the left side of the travel trajectory  50 , while the candidate terminal station position  70  is located on the right side of the travel trajectory  50 . Thus, the connecting line segment  90  crosses the travel trajectory  50 . In addition, in  FIG.  14   , the point of intersection between the connecting line segment  90  and the travel trajectory  50  is the intersection point  150  as in  FIG.  13   . However, in the “case b,” a part of the connecting line segment  90  is located outside the measurable range  110 . Therefore, although the connecting line segment  90  crosses the travel trajectory  50  in the “case b,” it is not appropriate to consider that the reliability of point group data obtained in the “case a” and the reliability of point group data obtained in the “case b” are equal. 
     Herein, as illustrated in  FIG.  14   , assume that the length of the connecting line segment  90  on the two-dimensional plane for which the vertical coordinate components are ignored, which is present within the measurable range  110 , is “u,” and the length thereof outside the measurable range  110  is “v.” In such a case, the proportion X[%] of the connecting line segment  90  on the two-dimensional plane for which the vertical coordinate components are ignored, which is present within the measurable range  110 , can be represented by the following Expression (1). 
         X=u /( u+v )×100[%]  (1)
 
     In the “case b,” regarding the “u” portion present within the measurable range  110 , it can be said that the reliability of point group data that can be acquired is equal to the reliability of point group data that can be acquired in the “case a.” 
     In contrast, regarding the “v” portion present outside the measurable range  110 , point group data cannot be acquired. Therefore, in the “case b,” when the overall point group data is considered, the reliability of the point group data is lower than that in the “case a.” In such a case, it is appropriate to consider that the degree of reliability of the processing result of a predetermined evaluation process drops to the proportion of the connecting line segment  90  present within the measurable range  110 , that is, X[%]. In the present embodiment, the value of X in Expression (1) above is the confidence coefficient. 
     It should be noted that the connecting line segment  90  present within the measurable range  110  (that is, the range indicated by “u”) further includes a line segment located within the neighboring range  100  and a line segment located outside the neighboring range  100 . The neighboring range  100  is a range closer to the travel trajectory  50  of a mobile object, such as a vehicle, having an MMS mounted thereon. Therefore, the inside of the neighboring range  100  is a range in which point group data can be collected with higher density than in the outside of the neighboring range  100 , and thus the reliability is higher. Thus, for example, the aforementioned “u” that represents the length of the connecting line segment  90  on the two-dimensional plane for which the vertical coordinate components are ignored, which is present within the measurable range  110 , may be further divided into a length “u 1 ” present within the neighboring range  100  and a length “u 2 ” present outside the neighboring range  100 , and weighting may be applied such that the value of u 1  becomes larger than that of u 2 . Accordingly, the accuracy of the value of the confidence coefficient X can be further increased. 
     Herein, referring again to  FIG.  4   , the configuration of the point group data processing unit  6   a  of the second embodiment will be described. The connecting line segment identification unit  26  generates connecting line segment data indicating the connecting line segment  90  connecting the candidate base station position  60  and the candidate terminal station position  70  based on the candidate base station position data indicating the candidate base station position  60  and the candidate terminal station position data indicating the candidate terminal station position  70 . 
     The measurable range proportion calculation unit  28  calculates the proportion of the connecting line segment  90  present within the measurable range  110 . 
     When the measurable range proportion calculation unit  28  has calculated the proportion X of the connecting line segment  90  present within the measurable range  110 , the confidence coefficient identification unit  22   a  identifies the calculated proportion X as the confidence coefficient. 
     Process of Second Embodiment 
       FIG.  15    is a flowchart illustrating a process flow of the point group data processing unit  6   a  of the second embodiment, and is a process corresponding to the (5) process of determining if communication is possible using three-dimensional point group data in the station deployment support method illustrated in  FIG.  2   . The flowchart of  FIG.  15    illustrates an example in which a three-dimensional visibility determination process of the three-dimensional visibility determination processing unit  23  is applied as a predetermined evaluation process performed by the point group data processing unit  6   a.    
     The candidate three-dimensional position selection unit  20  selects the candidate base station position  60  and the candidate terminal station position  70 , and outputs to the positional relationship identification unit  21   a  candidate base station position data indicating the candidate base station position  60  and candidate terminal station position data indicating the candidate terminal station position  70  (step Sa 1 ). Accordingly, the candidate base station position  60  and the candidate terminal station position  70  as processing targets are designated. 
     The measurable range identification unit  30  reads the travel trajectory data from the travel trajectory data storage unit  14  (step Sa 2 ). Then, the measurable range identification unit  30  generates measurable range data indicating the measurable range  110  based on the read travel trajectory data and the measurable distance determined in advance (step Sa 3 ). Then, the measurable range identification unit  30  outputs the generated measurable range data to the measurable range presence determination unit  31 . 
     The measurable range presence determination unit  31  captures the candidate base station position data and the candidate terminal station position data output from the candidate three-dimensional position selection unit  20  and the measurable range data output from the measurable range identification unit  30 . Then, the measurable range presence determination unit  31  determines if the candidate base station position  60  is located inside or outside the measurable range  110  based on the measurable range data and the candidate base station position data. Then, the measurable range presence determination unit  31  generates the determination result as base station positional relationship identification data, and writes and stores the generated base station positional relationship identification data into the determination result storage unit  34 . 
     In addition, the measurable range presence determination unit  31  determines if the candidate terminal station position  70  is located inside or outside the measurable range  110  based on the measurable range data and the candidate terminal station position data. Then, the measurable range presence determination unit  31  generates the determination result as terminal station positional relationship identification data, and writes and stores the generated terminal station positional relationship identification data into the determination result storage unit  34  (step Sa 4 ). 
     The measurable range presence determination unit  31  determines if the determination results indicate that both the candidate base station position  60  and the candidate terminal station position  70  are present within the measurable range  110  (step Sa 5 ). If the measurable range presence determination unit  31  determines that the determination results indicate that both the candidate base station position  60  and the candidate terminal station position  70  are present within the measurable range  110  (step Sa 5 , Yes), the measurable range presence determination unit  31  outputs an instruction signal for instructing the three-dimensional visibility determination processing unit  23  to start a process including the candidate base station position data and the candidate terminal station position data as the processing targets. 
     In step Sa 5 , if the measurable range presence determination unit  31  determines “Yes,” the reliability of point group data is high. Thus, it makes sense to perform a three-dimensional visibility determination process. 
     The three-dimensional visibility determination processing unit  23 , upon receiving the instruction signal from the measurable range presence determination unit  31 , reads from the point group data storage unit  13  point group data of a space between the candidate base station position  60  corresponding to the candidate base station position data and the candidate terminal station position  70  corresponding to the candidate terminal station position data that are included in the instruction signal, and performs a three-dimensional visibility determination process based on the read point group data (step Sa 6 ). 
     Meanwhile, if the measurable range presence determination unit  31  determines that the determination results indicate that at least one of the candidate base station position  60  or the candidate terminal station position  70  is not located within the measurable range  110  (step Sa 5 , No), the measurable range presence determination unit  31  determines if the determination results indicate that both the candidate base station position  60  and the candidate terminal station position  70  are present outside the measurable range  110  (step Sa 7 ). 
     If the measurable range presence determination unit  31  determines that the determination results indicate that both the candidate base station position  60  and the candidate terminal station position  70  are present outside the measurable range  110  (step Sa 7 , Yes), the measurable range presence determination unit  31  proceeds with the process to step Sa 8 . If the measurable range presence determination unit  31  determines “Yes” in step Sa 7 , point group data has not been acquired from the space between the candidate base station position  60  and the candidate terminal station position  70 . Therefore, since it is nonsense to perform a three-dimensional visibility determination process, the process of step Sa 6  is not performed. 
     Meanwhile, if the measurable range presence determination unit  31  determines that the determination results indicate that one of the candidate base station position  60  and the candidate terminal station position  70  is present within the measurable range  110  (step Sa 7 , No), the measurable range presence determination unit  31  proceeds with the process to step Sa 6 . If the measurable range presence determination unit  31  determines “No” in step Sa 7 , it makes some sense to perform a three-dimensional visibility determination process. Therefore, the process of step Sa 6  is performed. 
     It should be noted that among the aforementioned processes, the process of step Sa 1  is performed by the candidate three-dimensional position selection unit  20 , and the processes of steps Sa 2  to Sa 7  are performed by the positional relationship identification unit  21   a.    
     The connecting line segment identification unit  26  captures the candidate base station position data and candidate terminal station position data output from the confidence coefficient identification unit  22   a . Then, the connecting line segment identification unit  26  generates connecting line segment data indicating the connecting line segment  90  connecting the candidate base station position  60  and the candidate terminal station position  70  based on the captured candidate base station position data and candidate terminal station position data (step Sa 8 ). Then, the connecting line segment identification unit  26  outputs the generated connecting line segment data to the measurable range proportion calculation unit  28 . 
     The measurable range proportion calculation unit  28  captures the connecting line segment data output from the connecting line segment identification unit  26 . Then, the measurable range proportion calculation unit  28  reads the travel trajectory data from the travel trajectory data storage unit  14 , and calculates the length “u” of the connecting line segment  90  within the measurable range  110  and the length “v” of the connecting line segment  90  outside the measurable range  110  based on the read travel trajectory data, the connecting line segment data, and the measurable distance determined in advance. 
     The measurable range proportion calculation unit  28  calculates the proportion X[%] of the connecting line segment  90  on the two-dimensional plane for which the vertical coordinate components are ignored, which is present within the measurable range  110 , using Expression (1). Then, the measurable range proportion calculation unit  28  outputs to the confidence coefficient identification unit  22   a  data on the calculated value of X[%] and an output instruction signal. 
     The confidence coefficient identification unit  22   a  in a standby state captures the data on the value of X[%] upon receiving the data on the value of X[%] and the output instruction signal from the measurable range proportion calculation unit  28 . Then, the confidence coefficient identification unit  22   a  identifies the value of X[%] as the confidence coefficient (step Sa 9 ). 
     The confidence coefficient identification unit  22   a  displays on a screen the candidate base station position data and the candidate terminal station position data stored in the determination result storage unit  34  of the positional relationship identification unit  21   a  as well as the confidence coefficient, and the three-dimensional visibility determination processing unit  23  displays on the screen the processing result of the three-dimensional visibility determination process (step Sa 10 ). In contrast, when the process of step Sa 6  has not been performed and thus the three-dimensional visibility determination processing unit  23  has not output a processing result, the confidence coefficient identification unit  22   a  displays on the screen the candidate base station position data and the candidate terminal station position data as well as the confidence coefficient, and also displays information that “it has been impossible to perform a three-dimensional visibility determination process” (step Sa 10 ). 
     It should be noted that in the flowchart illustrated in  FIG.  15   , although a three-dimensional visibility determination process of the three-dimensional visibility determination processing unit  23  is used as a predetermined evaluation process, a shield factor calculation process of the shield factor calculation unit  24  may be used instead. 
     In addition, in the processes of steps Sa 8  and Sa 9  that are performed based on the connecting line segment  90  in the previously described flowchart in  FIG.  15   , the confidence coefficient may be identified by not only considering the proportion of the connecting line segment  90  present within the measurable range  110  but also considering the proportion of the connecting line segment  90  present within the neighboring range  100 . 
     In the station deployment support apparatus of the second embodiment, the connecting line segment identification unit  26  generates connecting line segment data indicating the connecting line segment  90  connecting the candidate base station position  60  and the candidate terminal station position  70  based on the candidate base station position data and the candidate terminal station position data. The confidence coefficient identification unit  22   a  identifies the confidence coefficient X indicating the degree of reliability of the processing result of a predetermined evaluation process performed based on point group data, based on the proportion of the connecting line segment  90  present within the measurable range  110 . 
     Accordingly, the confidence coefficient identification unit  22  can present to the user the confidence coefficient indicating the degree of reliability of the processing result of a predetermined evaluation process performed based on the point group data, for each candidate base station position and each candidate terminal station position. Therefore, when not all pieces of point group data have been acquired from the space between the candidate base station position and the candidate terminal station position, the reliability of the point group data is low, and in such a case, it is possible to allow the user to recognize from the confidence coefficient that the reliability of the processing result of a predetermined evaluation process performed using the point group data is also low. 
     For example, suppose that not all pieces of point group data have been acquired, but the three-dimensional visibility determination processing unit  23  indicates “visible” as a result of a determination process or the shield factor calculation unit  24  indicates “a sufficiently low shield factor that meets the requirement for wireless communication” as a result of a calculation process. Even in such a case, it is possible to urge the user to take precautions by presenting a confidence coefficient with a small value. Accordingly, it is possible to prevent the user from making erroneous determination, for example, selecting candidate positions for installing a base station and a terminal station in a space from which point group data, which serves as a basis for three-dimensional visibility determination or shield factor calculation, has not been acquired. 
     In addition, identifying the confidence coefficient can prompt the user to make the following determination depending on whether the value of the confidence coefficient is large or small. For example, suppose that not all pieces of point group data have been acquired from the space between the candidate base station position and the candidate terminal station position, but the value of the confidence coefficient is large. In such a case, it is possible to prompt the user to, regarding the combination of the candidate base station position and the candidate terminal station position to be considered, determine that consideration using the acquired point group data is possible. 
     Further, identifying the confidence coefficient can also allow the three-dimensional visibility determination processing unit  23  to determine whether to perform a three-dimensional visibility determination process or allow the shield factor calculation unit  24  to determine whether to calculate the shield factor depending on whether the value of the confidence coefficient is large or small. For example, the three-dimensional visibility determination processing unit  23  or the shield factor calculation unit  24  may be configured to, when the value of the confidence coefficient is small, not perform a process for a combination of the candidate base station position and the candidate terminal station position as the processing targets, so that the amount of calculation can be reduced. Further, when the user is notified of the fact that the three-dimensional visibility determination processing unit  23  or the shield factor calculation unit  24  has not performed a process, the user can be prompted to acquire point group data again from the space between the candidate base station position and the candidate terminal station position as the processing targets or reconsider the candidate base station position and the candidate terminal station position. Therefore, even when the state of acquisition of point group data from the space between the candidate base station position and the candidate terminal station position is not good, the user can perform appropriate station deployment design. 
     Third Embodiment 
     Hereinafter, a third embodiment of the present invention will be described with reference to the drawings. First, with reference to  FIGS.  16  to  19   , the positional relationship between an evaluation area E described below and the travel trajectory  50 , given as an example of the present embodiment, will be described. 
       FIG.  16    is a view representing a map of an urban area. It should be noted that the map illustrated in  FIG.  9    described previously corresponds to an upper left portion of the map illustrated in  FIG.  16   . In  FIG.  16   , a region of the road  400  is illustrated in a lattice pattern as in  FIG.  9   . Each of a plurality of regions partitioned in a lattice pattern by the regions of the road  400  is the site  300 . Each site  300  includes a plurality of buildings  310  indicated by a rectangular shape.  FIG.  16    also illustrates a travel trajectory  50   a  of a mobile object, such as a vehicle, having an MMS mounted thereon, and a measurable range  110   a  is illustrated along the travel trajectory  50   a . It should be noted that in  FIGS.  16  to  19   , the illustration of the aforementioned neighboring range  100  is omitted. 
     In the present embodiment, it is assumed that the range of the map illustrated in  FIG.  16    is the evaluation area E. The evaluation area E is a target area for the user to perform station deployment design of base stations and terminal stations. Therefore, it is desirable that the measurable range  110  spread across the entire evaluation area E. However, as illustrated in  FIG.  16   , the measurable range  110   a  that is based on the travel trajectory  50   a  does not cover the entire evaluation area E. 
     It should be noted that there are a variety of reasons that the measurable range  110   a  that is based on the travel trajectory  50   a  cannot cover the entire evaluation area E. For example, there is a range in which a mobile object, such as a vehicle, having an MMS mounted thereon is not allowed to travel due to traffic regulations or the like (for example, due to one-way traffic, prohibition of right and left turns at an intersection or straight travel, or regulations due to construction). 
       FIGS.  17  to  19    each represent a map of an urban area corresponding to the same range as that of the evaluation area E illustrated in  FIG.  16   .  FIG.  17    illustrates a travel trajectory  50   b  of a mobile object, such as a vehicle, having an MMS mounted thereon, and a measurable range  110   b  is illustrated along the travel trajectory  50   b . As illustrated in  FIG.  17   , the measurable range  110   b  that is based on the travel trajectory  50   b  does not cover the entire evaluation area E as with the measurable range  110   a  illustrated in  FIG.  16   . 
     In addition,  FIG.  18    illustrates a travel trajectory  50   c  of a mobile object, such as a vehicle, having an MMS mounted thereon, and a measurable range  110   c  is illustrated along the travel trajectory  50   c . As illustrated in  FIG.  18   , the measurable range  110   c  that is based on the travel trajectory  50   c  does not cover the entire evaluation area E as with the measurable range  110   a  illustrated in  FIG.  16   . 
     As described above, the travel trajectories  50   a  to  50   c  illustrated in  FIGS.  16  to  18   , respectively, are different travel trajectories, and the measurable ranges  110   a  to  110   c  are different measurable ranges. In addition, none of the measurable ranges  110   a  to  110   c  covers the entire evaluation area E. 
     Meanwhile, in  FIG.  19   , all of the travel trajectories  50   a  to  50   c  and the measurable ranges  110   a  to  110   c  illustrated in  FIGS.  16  to  18   , respectively, are illustrated in a map. In this manner, combining the measurable ranges  110  that are based on the plurality of travel trajectories  50  allows more regions of the evaluation area E to be included in the measurable range  110 . 
     For example, for each of a total of 48 sites  300  (hereinafter also referred to as “plots”) included in the evaluation area E, the number of buildings  310  in the measurable range  110   a  illustrated in  FIG.  16    is counted. Each plot included in the evaluation area E includes about four buildings  310 . In  FIG.  16   , the number of plots in which 3 to 4 buildings  310  are included in the measurable range  110   a , the number of plots in which 1 to 2 buildings  310  are included in the measurable range  110   a , and the number of plots in which no building  310  is present in the measurable range  110   a  are 14 plots, 11 plots, and 23 plots, respectively. 
     Similarly, for example, for each of a total of 48 plots included in the evaluation area E, the number of buildings  310  in the measurable range  110   b  illustrated in  FIG.  17    is counted. In  FIG.  17   , the number of plots in which 3 to 4 buildings  310  are included in the measurable range  110   b , the number of plots in which 1 to 2 buildings  310  are included in the measurable range  110   b , and the number of plots in which no building  310  is present in the measurable range  110   b  are 12 plots, 9 plots, and 27 plots, respectively. 
     Similarly, for example, for each of a total of 48 plots included in the evaluation area E, the number of buildings  310  in the measurable range  110   c  illustrated in  FIG.  18    is counted. In  FIG.  18   , the number of plots in which 3 to 4 buildings  310  are included in the measurable range  110   b , the number of plots in which 1 to 2 buildings  310  are included in the measurable range  110   b , and the number of plots in which no building  310  is present in the measurable range  110   b  are 19 plots, 14 plots, and 15 plots, respectively. 
       FIG.  20    is a table aggregating the aforementioned count results. As illustrated in  FIG.  20   , regarding each of the measurable range  110   a  that is based on travel trajectory  50   a , the measurable range  110   b  that is based on the travel trajectory  50   b , and the measurable range  110   c  that is based on the travel trajectory  50   c , the number of plots in which 3 to 4 buildings  310  are included in the measurable range  110   a , the measurable range  110   b , or the measurable range  110   c  is 12 to 19 plots at the most, and its proportion is about 25[%] to 40[%] at the most. In addition, even when counting is performed by further including the number of plots in which 1 to 2 buildings  310  are included in the measurable range  110   a , the measurable range  110   b , or the measurable range  110   c , the number of plots in which 1 to 4 buildings  310  are included in the measurable range  110   a , the measurable range  110   b , or the measurable range  110   c  is about 21 to 33 plots at the most, and its proportion is about 44[%] to 69[%]. 
     In contrast, as illustrated in  FIG.  20   , regarding the measurable range  110  combining the measurable range  110   a  that is based on the travel trajectory  50   a , the measurable range  110   b  that is based on the travel trajectory  50   b , and the measurable range  110   c  that is based on the travel trajectory  50   c , the number of plots in which 3 to 4 buildings  310  are included in the measurable range  110  is increased up to 42 plots, and its proportion is increased up to 88[%]. In addition, when counting is performed by further including the number of plots in which 1 to 2 buildings  310  are included in the measurable range  110  (which combines the measurable range  110   a , the measurable range  110   b , and the measurable range  110   c ), the number of plots in which 1 to 4 buildings  310  are included in the measurable range  110  is increased up to 46 plots, and its proportion is increased up to 96[%]. 
     In this manner, when the measurable ranges  110  that are based on the plurality of travel trajectories  50  are superposed, in the case of the examples illustrated in  FIGS.  16  to  20   , for example, the probability that both the candidate base station position  60  and the candidate terminal station position  70  are included in the measurable range  110  (which combines the measurable range  110   a , the measurable range  110   b , and the measurable range  110   c ) is at least 77[%](=88[%]×88[%]). Meanwhile, when the measurable range  110  is only the measurable range  110   a  that is based on the travel trajectory  50   a  illustrated in  FIG.  16   , for example, the probability that both the candidate base station position  60  and the candidate terminal station position  70  are included in the measurable range  110  (which includes only the measurable range  110   a ) is about 8[%](=29[%]×29[%]). 
     In this manner, when point group data is acquired based on the plurality of travel trajectories  50  (which include the travel trajectory  50   a , the travel trajectory  50   b , and the travel trajectory  50   c ), the region of the measurable range  110  (which combines the measurable range  110   a , the measurable range  110   b , and the measurable range  110   c ) is significantly expanded. Accordingly, it is possible to improve the accuracy of visibility determination or shield factor calculation (that is, increase the value of the confidence coefficient), and thus improve the accuracy of station deployment design. 
     Hereinafter, the configuration of a point group data processing unit  6   b  of the third embodiment will be described. 
       FIG.  21    is a block diagram illustrating the internal configuration of the point group data processing unit  6   b  applied to the third embodiment. In the third embodiment, components identical to those of the first embodiment and the second embodiment are denoted by identical reference signs. In the following description, a station deployment support apparatus of the third embodiment shall be referred to as a station deployment support apparatus  1   b  with a reference sign “ 1   b ” added thereto, though not illustrated in the drawings. The station deployment support apparatus  1   b  has a configuration obtained by replacing the point group data processing unit  6  in the station deployment support apparatus  1  of the first embodiment with the point group data processing unit  6   b  illustrated in  FIG.  21   . 
     The point group data processing unit  6   b  includes the candidate three-dimensional position selection unit  20 , a positional relationship identification unit  21   b , a confidence coefficient identification unit  22   b , the three-dimensional visibility determination processing unit  23 , the shield factor calculation unit  24 , the storage unit  25 , the connecting line segment identification unit  26 , the measurable range proportion calculation unit  28 , and a travel trajectory selection unit  29 . The positional relationship identification unit  21   b  includes the measurable range identification unit  30 , the measurable range presence determination unit  31 , the neighboring range identification unit  32 , the neighboring range presence determination unit  33 , and the determination result storage unit  34 . In this manner, the point group data processing unit  6   b  has a configuration obtained by adding the travel trajectory selection unit  29  to the point group data processing unit  6   a  of the second embodiment illustrated in  FIG.  4   . 
     The travel trajectory selection unit  29  calculates the proportion of a portion of the evaluation area E within the measurable range  110  that is based on the existing travel trajectory  50 . If the calculated proportion is less than a predetermined threshold (for example, 70[%]), the travel trajectory selection unit  29  determines if there is any other (new) travel trajectory  50  that achieves a high proportion when the measurable range  110  that is based on the other (new) travel trajectory  50  is combined with the measurable range  110  that is based on the existing travel trajectory  50 . If there is any other travel trajectory  50  that achieves a high proportion, the travel trajectory selection unit  29  causes the measurable range identification unit  30  to read from the travel trajectory data storage unit  14  travel trajectory data indicating the other (new) travel trajectory  50 . 
     Although the travel trajectory selection unit  29  in the present embodiment is configured to, based on the proportion of a portion of the evaluation area E within the measurable range  110  that is based on the existing travel trajectory  50 , determine whether to use point group data that is based on another (new) travel trajectory  50 , the present invention is not limited thereto. For example, the travel trajectory selection unit  29  may perform the determination using a visibility determination result of the three-dimensional visibility determination processing unit  23 , a shield factor calculation result of the shield factor calculation unit  24 , a confidence coefficient calculation result of the confidence coefficient identification unit  22   b  and the like. 
     Process of Third Embodiment 
     Hereinafter, an exemplary process of the point group data processing unit  6   b  will be described. 
       FIG.  22    is a flowchart illustrating a process flow of the point group data processing unit  6   b  of the third embodiment. First, the point group data processing unit  6   b  designates the range of the evaluation area E (step Sb 01 ). Next, the point group data processing unit  6   b  reads the first travel trajectory data. Then, the point group data processing unit  6   b  reflects the measurable range  110 , which is based on the read travel trajectory data, in the evaluation area E (step Sb 02 ). 
     The point group data processing unit  6   b  calculates the proportion of a portion of the evaluation area E within the measurable range  110  that is based on the existing travel trajectory  50 , for example, thereby determining if there are many places outside the measurable range  110  (step Sb 03 ). Alternatively, the point group data processing unit  6   b  determines if there are many places with a low confidence coefficient regarding the visibility or the shield factor of a space between the candidate base station position  60  and the candidate terminal station position  70  in the evaluation area E, for example (step Sb 03 ). 
     If the point group data processing unit  6   b  determines that there are many places outside the measurable range  110  (or determines that there are many places with a low confidence coefficient) (step Sb 03 , Yes), the point group data processing unit  6   b  determines if there is any other (new) travel trajectory  50  that can reduce the places outside the measurable range  110  (or the places with a low confidence coefficient) when the measurable range  110  that is based on the other (new) travel trajectory  50  is combined with the measurable range  110  that is based on the existing travel trajectory  50  (step Sb 04 ). 
     If the point group data processing unit  6   b  determines that there is another (new) travel trajectory  50  that can reduce the places outside the measurable range  110  (or the places with a low confidence coefficient) (step Sb 04 , Yes), the point group data processing unit  6   b  selects the other (new) travel trajectory  50  and reads travel trajectory data indicating the selected travel trajectory  50 . Then, the point group data processing unit  6   b  reflects the measurable range  110 , which is based on the read travel trajectory data, in the evaluation area E (step Sb 05 ). Then, the point group data processing unit  6   b  repeats the operation of from step Sb 03  again. 
     Meanwhile, if the point group data processing unit  6   b  determines that there is no other (new) travel trajectory  50  that can reduce the places outside the measurable range  110  (or the places with a low confidence coefficient) (step Sb 04 , No), the point group data processing unit  6   b  presents to the user information indicating that there are many places outside the measurable range  110  (or places with a low confidence coefficient) (step Sb 06 ). Accordingly, the process of the point group data processing unit  6   b  illustrated in the flowchart of  FIG.  22    ends. 
     Meanwhile, if the point group data processing unit  6   b  determines that there are not many places outside the measurable range  110  (step Sb 03 , No), the point group data processing unit  6   b  determines if the supposed candidate base station position  60  and candidate terminal station position  70  are located within the measurable range  110  (step Sb 07 ). Alternatively, if the point group data processing unit  6   b  determines that there are not many places with a low confidence coefficient (step Sb 03 , No), the point group data processing unit  6   b  determines if the supposed candidate base station position  60  and candidate terminal station position  70  are the positions where the confidence coefficient (of visibility determination or shield factor calculation) is higher (than a predetermined value, for example) (step Sb 07 ). 
     If the point group data processing unit  6   b  determines that the supposed candidate base station position  60  and candidate terminal station position  70  are not located within the measurable range  110  (step Sb 07 , No), the point group data processing unit  6   b  presents to the user information indicating that the supposed candidate base station position  60  and candidate terminal station position  70  are outside the measurable range  110  (step Sb 08 ). Alternatively, if the point group data processing unit  6   b  determines that the supposed candidate base station position  60  and candidate terminal station position  70  are not the positions where the confidence coefficient is high (step Sb 07 , No), the point group data processing unit  6   b  presents to the user information indicating that the supposed candidate base station position  60  and candidate terminal station position  70  are the positions where the confidence coefficient is low (step Sb 08 ). Accordingly, the process of the point group data processing unit  6   b  illustrated in the flowchart of  FIG.  22    ends. 
     Meanwhile, if the point group data processing unit  6   b  determines that the supposed candidate base station position  60  and candidate terminal station position  70  are located within the measurable range  110  (step Sb 07 , Yes), the point group data processing unit  6   b  presents to the user information indicating all of the selected travel trajectories  50  (step Sb 09 ). 
     Alternatively, if the point group data processing unit  6   b  determines that the supposed candidate base station position  60  and candidate terminal station position  70  are the positions where the confidence coefficient is high (step Sb 07 , Yes), the point group data processing unit  6   b  presents to the user information indicating all of the selected travel trajectories  50  (step Sb 09 ). Accordingly, the process of the point group data processing unit  6   b  illustrated in the flowchart of  FIG.  22    ends. 
     As described above, the point group data processing unit  6   b  in the station deployment support apparatus  1   b  of the third embodiment includes the travel trajectory selection unit  29  that selects at least one piece of travel trajectory data so that the proportion of the predetermined evaluation area E occupied by the measurable range  110  satisfies a predetermined value, for example. With such a configuration, the station deployment support apparatus  1   b  can improve the state of acquisition of point group data from the space between the candidate base station position  60  and the candidate terminal station position  70 . This allows the user to perform appropriate station deployment design. 
     Fourth Embodiment 
     Hereinafter, a fourth embodiment of the present invention will be described with reference to the drawings. 
     In the following description, a station deployment support apparatus of the fourth embodiment shall be referred to as a station deployment support apparatus  1   c  with a reference sign “ 1   c ” added thereto. In addition, a point group data processing unit in the station deployment support apparatus  1   c  of the fourth embodiment shall be referred to as a point group data processing unit  6   c  with a reference sign “ 6   c ” added thereto. 
       FIG.  23    is a view representing a map of an urban area.  FIG.  23    illustrates the evaluation area E, the travel trajectories  50   a  to  50   c , and the measurable ranges  110   a  to  110   c  illustrated in  FIG.  19    described previously. However,  FIG.  23    differs from  FIG.  19    in that  FIG.  23    illustrates an overlap (hereinafter referred to as an “overlapped area”) of two of the measurable ranges  110   a  to  110   c  that occur when two of the travel trajectories  50   a  to  50   c  cross each other. 
       FIG.  23    illustrates five overlapped areas (each corresponding to an intersection of different travel trajectories in the example illustrated in  FIG.  23   ).  FIG.  24    is an enlarged view of a range P including one of the overlapped areas illustrated in  FIG.  23   . As illustrated in  FIG.  24   , the range P includes an overlapped area of the measurable range  110   b  corresponding to the travel trajectory  50   b  and the measurable range  110   c  corresponding to the travel trajectory  50   c.    
     In the overlapped area, a mobile object, such as a vehicle, having an MMS mounted thereon travels a plurality of times. Thus, point group data is collected a plurality of times. Therefore, in the overlapped area illustrated in  FIG.  24   , station deployment setting can be performed using either point group data in the measurable range  110   b  or point group data in the measurable range  110   c . However, point group data is collected at a higher density at a position closer to the travel trajectory  50 . In addition, when point group data collected at a higher density is used, the accuracy of station deployment design improves. Therefore, which of the accuracy of station deployment design performed using point group data in the measurable range  110   b  or that performed using point group data in the measurable range  110   c  is higher differs depending on the position of the candidate base station position  60  or the candidate terminal station position  70  in the overlapped area. 
       FIG.  24    illustrates each of a region in which station deployment design can be performed with higher accuracy using point group data in the measurable range  110   b  and a region in which station deployment design can be performed with higher accuracy using point group data in the measurable range  110   c . As illustrated in  FIG.  24   , a line connecting the intersection of the travel trajectory  50   b  and the travel trajectory  50   c  and each apex of the overlapped area is the boundary between the region in which station deployment design can be performed with higher accuracy using point group data in the measurable range  110   b  and the region in which station deployment design can be performed with higher accuracy using point group data in the measurable range  110   c.    
     The point group data processing unit  6   c  in the station deployment support apparatus  1   c  of the fourth embodiment performs, when one of the candidate base station position  60  or the candidate terminal station position  70  is located in the overlapped area, visibility determination or shield factor calculation using point group data in the measurable range  110  with which station deployment design can be performed with higher accuracy. The point group data in the measurable range  110  with which station deployment design can be performed with higher accuracy is the point group data included in the measurable range  110  that is based on the travel trajectory  50  located closer to the candidate base station position  60  or the candidate terminal station position  70  as described above. Accordingly, the station deployment support apparatus  1   c  of the fourth embodiment can further improve the accuracy of station deployment design. 
     In addition, as described above, since a mobile object, such as a vehicle, having an MMS mounted thereon travels in the overlapped area a plurality of times, point group data is collected a plurality of times. Herein, an environment, such as road conditions, may differ at a timing when the mobile object, such as a vehicle, having an MMS mounted thereon travels along the travel trajectory  50   b  and at a timing when the mobile object travels along the travel trajectory  50   c . For example, there is a case where visibility is shielded when the mobile object passes a large vehicle or the like during acquisition of point group data at one of the two timings. In addition, for example, there is also a case where visibility is shielded when a large vehicle or the like stops on the side of the road during acquisition of point group data at one of the two timings. 
     As described above, there is a case where point group data in the measurable range  110   b  and point group data in the measurable range  110   c  in the overlapped area do not coincide due to the difference in the timing of collecting such point group data. However, based on such point group data being different, the station deployment support apparatus  1   c  can recognize the overlapped area as a place where the communication state is likely to fluctuate (i.e., the communication stability is low), for example. In addition, the station deployment support apparatus  1   c  can present to the user information that the overlapped area is a place where the communication state is likely to fluctuate, for example. 
     As described above, the point group data processing unit  6   c  in the station deployment support apparatus  1   c  of the fourth embodiment performs, when the measurable ranges  110  that are based on the plurality of travel trajectories  50  selected by the travel trajectory selection unit  29  overlap one another, a predetermined evaluation process (i.e., a visibility determination process or a shield factor calculation process) based on point group data included in the measurable range  110  that is based on the travel trajectory  50  located closer to a position indicated by the candidate base station position  60  or the candidate terminal station position  70 . Accordingly, the station deployment support apparatus  1   c  of the fourth embodiment can improve the accuracy of station deployment design more. 
     Fifth Embodiment 
     Hereinafter, a fifth embodiment of the present invention will be described with reference to the drawings. 
     In the following description, a station deployment support apparatus of the fifth embodiment shall be referred to as a station deployment support apparatus  1   d  with a reference sign “ 1   d ” added thereto. In addition, a point group data processing unit in the station deployment support apparatus  1   d  of the fifth embodiment shall be referred to as a point group data processing unit  6   d  with a reference sign “ 6   d ” added thereto. 
     In the fifth embodiment, a mobile object, such as a vehicle, having an MMS mounted thereon travels along an identical travel trajectory  50  a plurality of times. Accordingly, the station deployment support apparatus  1   d  of the present embodiment can collect pieces of point group data measured a plurality of times at an identical location at different timings. 
       FIG.  25    illustrates the state at a given timing of a place corresponding to the “case b” represented by the positional relationship configuration  200   b  in  FIG.  7    described previously. As illustrated in  FIG.  25   , a truck tk stops between the candidate base station position  60  and the candidate terminal station position  70 . Therefore, the Fresnel zone  80  between the candidate base station position  60  and the candidate terminal station position  70  is shielded by the truck tk. When point group data obtained at a timing when the truck tk stops around the candidate base station position  60  and the candidate terminal station position  70  is used, the visibility determination result of the three-dimensional visibility determination processing unit  23  indicates “not visible.” In addition, when point group data obtained at such a timing is used, the shield factor calculation result of the shield factor calculation unit  24  indicates a “high shield factor.” 
     However, at a timing when no vehicle, such as a truck tk, stops around the candidate base station position  60  and the candidate terminal station position  70 , the Fresnel zone  80  between the candidate base station position  60  and the candidate terminal station position  70  is not shielded. Therefore, when point group data obtained at a timing when no vehicle, such as a truck tk, stops around the candidate base station position  60  and the candidate terminal station position  70  is used, the visibility determination result of the three-dimensional visibility determination processing unit  23  indicates “visible.” In addition, when point group data obtained at such a timing is used, the shield factor calculation result of the shield factor calculation unit  24  indicates a “low shield factor.” 
     The station deployment support apparatus  1   d  of the present embodiment can, by comparing pieces of point group data measured a plurality of times at an identical location at different timings, estimate whether an object shielding a space between the candidate base station position  60  and the candidate terminal station position  70  is an object that is always present or an object that is temporarily present (such as a truck tk that temporarily stops as described above, for example). 
     In addition, the station deployment support apparatus  1   d  of the present embodiment can recognize the frequency (or the proportion) of the presence of an object that temporarily shields the Fresnel zone  80  between the candidate base station position  60  and the candidate terminal station position  70  by performing visibility determination or shield factor calculation using pieces of point group data repeatedly measured at an identical location at different timings. Accordingly, the station deployment support apparatus  1   d  can estimate the likelihood of fluctuation of the communication state (i.e., communication stability). In addition, the station deployment support apparatus  1   d  can present the estimation result to the user. 
       FIG.  26    is a graph illustrating an exemplary transition of the shield factor of a space between a given candidate base station position  60  and a given candidate terminal station position  70 . In the graph illustrated in  FIG.  26   , the ordinate axis represents the shield factor and the abscissa axis represents the time (in  FIG.  26   , the range in which the shield factor is high is indicated by H, and the range in which the shield factor is low is indicated by L). As illustrated in  FIG.  26   , there are three timings when the shield factor is particularly high within the time illustrated in the graph. Each of the timings when the shield factor is particularly high (such as a measurement point p 2  in the range indicated by H in  FIG.  26   ) is a timing when a large vehicle or the like temporarily stops between the candidate base station position  60  and the candidate terminal station position  70  as illustrated in  FIG.  25   , for example. 
     In the time period in which the shield factor has transitioned to a low level (i.e., the range indicated by L including measurement points p 1  and p 3  to p 5  in  FIG.  26   ), the shield factor fluctuates slightly. Such fluctuation occurs when a small vehicle, a passenger, or the like passes, for example. A mobile object, such as a vehicle, having an MMS mounted thereon travels at five timings including p 1  to p 5 , for example, within the time illustrated in the graph to acquire point group data. Among such five timings, only the timing p 2  is a timing when a large vehicle or the like temporarily stops between the candidate base station position  60  and the candidate terminal station position  70 . 
     Therefore, since the shield factor has been high only in one measurement among the five measurements, the station deployment support apparatus  1   d  of the present embodiment can estimate that the shield factor is at a low level in about 80[%] of the total time period, for example. Although an example in which five measurement points are used has been briefly described with reference to the graph in  FIG.  26   , it is obviously necessary to utilize a number of measurement points to present a more precise numerical proportion of the time period in which the shield factor is low. In addition, the station deployment support apparatus  1   d  can present to the user an estimation result indicating that the combination of the candidate base station position  60  and the candidate terminal station position  70  as the evaluation targets is a combination of positions where communication is generally possible. 
     Process of Fifth Embodiment 
     Hereinafter, an exemplary process of the station deployment support apparatus  1   d  will be described. 
       FIG.  27    is a flowchart illustrating a process flow of the station deployment support apparatus  1   d  of the fifth embodiment. 
     When a mobile object, such as a vehicle, having an MMS mounted thereon has traveled an identical place a plurality of times, the point group data processing unit  6   d  collects point group data obtained through each travel (step Sc 01 ). Then, the point group data processing unit  6   d  calculates the shield factor of the space between the candidate base station position  60  and the candidate terminal station position  70  based on point group data obtained through a given travel among the collected pieces of point group data (step Sc 02 ). 
     Then, the point group data processing unit  6   d  determines if the shield factor of the space between the candidate base station position  60  and the candidate terminal station position has been calculated based on point group data obtained through all travels (step Sc 03 ). If it is determined that there is another piece of point group data that has not been used for the calculation of the shield factor of the space between the candidate base station position  60  and the candidate terminal station position  70  (step Sc 03 , No), the point group data processing unit  6   d  reads the other piece of point group data that has not been used for the calculation (step Sc 04 ). Then, the point group data processing unit  6   d  repeats the processes of from step Sc 02  described above again. 
     Meanwhile, if the point group data processing unit  6   d  determines that the shield factor of the space between the candidate base station position  60  and the candidate terminal station position  70  has been calculated based on point group data obtained through all travels (step Sc 03 , Yes), the point group data processing unit  6   d  determines if all of the calculated shield factors are sufficiently low values (step Sc 05 ). It should be noted that the point group data processing unit  6   d  performs such determination based on whether all of the calculated shield factors are less than or equal to a predetermined value determined in advance by the user, for example. 
     If it is determined that all of the calculated shield factors are sufficiently low values (step Sc 05 , Yes), the station deployment support apparatus  1   d  presents to the user information indicating that the combination of the candidate base station position  60  and the candidate terminal station position  70 , which are the evaluation targets, is a combination where communication is always possible (step Sc 06 ). Accordingly, the processes illustrated in the flowchart of  FIG.  27    end. 
     Meanwhile, if it is determined that at least one of the calculated shield factors is not a sufficiently low value (step Sc 05 , No), the point group data processing unit  6   d  determines if the number of times the shield factor has been high is small (step Sc 07 ). It should be noted that the point group data processing unit  6   d  performs such determination based on whether the number of times the shield factor has not been determined to be a low value (that is, the number of times the shield factor has been determined to be a high value) is less than or equal to the number of times determined in advance by the user, for example. 
     If it is determined that the number of times the shield factor has been high is not small (that is, large) (step Sc 07 , No), the point group data processing unit  6   d  changes the candidate base station position  60  and the candidate terminal station position  70  as the evaluation targets (step Sc 08 ). Then, the point group data processing unit  6   d  repeats the processes of from step Sc 02  described above again. 
     Meanwhile, if it is determined that the number of times the shield factor has been high is small (step Sc 07 , Yes), the station deployment support apparatus  1   d  presents to the user information indicating that the combination of the candidate base station position  60  and the candidate terminal station position  70 , which are the evaluation targets, is a combination where communication is generally possible (that is, communication is possible at many timings) (step Sc 09 ). Accordingly, the processes illustrated in the flowchart of  FIG.  27    end. 
     Although the point group data processing unit  6   d  in the present embodiment is configured to determine if the combination of the candidate base station position  60  and the candidate terminal station position  70  is a combination where communication is possible based on the calculation results of the shield factors, the present invention is not limited thereto. For example, the point group data processing unit  6   d  may be configured to determine if the combination of the candidate base station position  60  and the candidate terminal station position  70  is a combination where communication is possible based on the determination result of visibility. 
     As described above, the point group data processing unit  6   d  in the station deployment support apparatus  1   d  of the fifth embodiment performs, based on an identical candidate base station position  60 , an identical candidate terminal station position  70 , and a plurality of pieces of point group data obtained at different timings, a predetermined evaluation process (i.e., a visibility determination process or a shield factor calculation process) for each piece of the point group data. Then, the station deployment support apparatus  1   d  generates information about the communication state based on the result of the predetermined evaluation process obtained for each piece of the point group data, and presents the information. The information about the communication state herein is information indicating the likelihood of fluctuation of the communication state (i.e., communication stability), for example, as described above. With such a configuration, the station deployment support apparatus  1   d  of the fifth embodiment can further improve the accuracy of station deployment design. 
     Sixth Embodiment 
     Hereinafter, a sixth embodiment of the present invention will be described with reference to the drawings. 
     In the following description, a station deployment support apparatus of the sixth embodiment shall be referred to as a station deployment support apparatus  1   e  with a reference sign “ 1   e ” added thereto. In addition, a point group data processing unit in the station deployment support apparatus  1   e  of the sixth embodiment shall be referred to as a point group data processing unit  6   e  with a reference sign “ 6   e ” added thereto. 
     In the sixth embodiment, a mobile object, such as a vehicle, having an MMS mounted thereon travels along an identical travel trajectory  50  a plurality of times as in the aforementioned fifth embodiment. Accordingly, the station deployment support apparatus  1   e  of the present embodiment can collect pieces of point group data measured a plurality of times at an identical location at different timings. 
     It should be noted that the sixth embodiment differs from the aforementioned fifth embodiment in that the fifth embodiment is intended to estimate the influence of a temporary stop of a large vehicle or the like on the communication (that is, a change in the communication state that occurs in a relatively short period of time), for example, while the sixth embodiment is intended to estimate the influence of a phenomenon that occurs depending on the period (e.g., the season) on the communication (that is, a change in the communication state that occurs in a relatively long period of time), for example. Therefore, the length of each of a plurality travels of a mobile object, such as a vehicle, having an MMS mounted thereon is typically longer in the sixth embodiment than in the fifth embodiment. 
       FIGS.  28  and  29    each illustrate the state at a given timing of a place corresponding to the “case b” represented by the positional relationship configuration  200   b  in  FIG.  7    described previously. As illustrated in  FIGS.  28  and  29   , a tree tr is present between the candidate base station position  60  and the candidate terminal station position  70 . The tree tr is a broad-leaved tree, and in  FIG.  28   , the tree tr is in a densely grown state. That is,  FIG.  28    illustrates the spring or summer season as the timing, for example. Therefore, the Fresnel zone  80  between the candidate base station position  60  and the candidate terminal station position  70  is shielded by the tree tr. 
     As roadside trees, broad-leaved trees (or deciduous trees) are planted for the reasons that tree-shaded areas are provided in the summer and sunlight is received in the winter, for example. Therefore, when a road and an its surrounding area are supposed, the candidate base station position  60  illustrated in  FIG.  28    or  FIG.  29    corresponds to a utility pole on the side of the road. In addition, the candidate terminal station position  70  corresponds to a wall surface of a building around the road. Further, the tree tr as a roadside tree, which is planted between the candidate positions of the two stations, is present. That is, when the road on which such a tree tr is present and its surrounding area are seen, the sixth embodiment (i.e., the circumstance illustrated in  FIG.  28    or  FIG.  29   , for example) illustrates a commonly supposed circumstance. 
     When point group data, which is obtained at a timing when the neighboring tree tr has grown densely, is used, the visibility determination result of the three-dimensional visibility determination processing unit  23  indicates “not visible.” In addition, when point group data obtained at such a timing is used, the shield factor calculation result of the shield factor calculation unit  24  indicates a “high shield factor.” 
     Meanwhile, in  FIG.  29   , the tree tr has its leaves fallen off. That is,  FIG.  29    illustrates the autumn or winter season as the timing, for example. Therefore, the Fresnel zone  80  between the candidate base station position  60  and the candidate terminal station position  70  is not shielded by the tree tr much. When point group data, which is obtained at a timing when the neighboring tree tr has its leaves fallen off, is used, the visibility determination result of the three-dimensional visibility determination processing unit  23  indicates “visible.” In addition, when point group data obtained at such a timing is used, the shield factor calculation result of the shield factor calculation unit  24  indicates a “low shield factor.” 
     The station deployment support apparatus  1   e  of the present embodiment can, by comparing pieces of point group data measured a plurality of times at an identical location at different timings with one another, estimate whether a phenomenon that shields the space between the candidate base station position  60  and the candidate terminal station position  70  is a phenomenon that occurs always or a phenomenon that occurs depending on the period (like the tree tr with its state of leaves changing depending on the season, for example). 
     In addition, the station deployment support apparatus  1   e  of the present embodiment can, by performing visibility determination or shield factor calculation using pieces of point group data repeatedly measured at an identical location at different timings, recognize the period of the occurrence of a phenomenon that shields the Fresnel zone  80  between the candidate base station position  60  and the candidate terminal station position  70 . Accordingly, the station deployment support apparatus  1   e  can estimate the period in which the communication state is good (or bad). In addition, the station deployment support apparatus  1   e  can present the estimation result to the user. 
       FIG.  30    is a graph illustrating an exemplary transition of the shield factor of a space between a given candidate base station position  60  and a given candidate terminal station position  70 . In the graph illustrated in  FIG.  30   , the ordinate axis represents the shield factor and the abscissa axis represents the time (i.e., the season) (in  FIG.  30   , the range in which the shield factor is high is indicated by H, and the range in which the shield factor is low is indicated by L). As illustrated in  FIG.  30   , there is a period in which the shield factor is high within the time illustrated in the graph. Such a timing when the shield factor is high is a timing when the leaves of the tree tr present between the candidate base station position  60  and the candidate terminal station position  70  have grown densely as illustrated in  FIG.  28   , for example. Meanwhile, as illustrated in  FIG.  30   , there is also a period in which the shield factor is low within the time illustrated in the graph. Such a timing when the shield factor is low is a timing when the leaves of the tree tr present between the candidate base station position  60  and the candidate terminal station position  70  have fallen off as illustrated in  FIG.  29   , for example. 
     A mobile object, such as a vehicle, having an MMS mounted thereon travels at 6 timings including q 1  to q 6 , for example, within the time illustrated in the graph, to acquire point group data. Among such 6 timings, each of the timings q 2  and q 3  (i.e., measurement points in the range H in which the shield factor is high in  FIG.  30   ) is the spring or summer timing, and thus is a timing when the leaves of the tree tr between the candidate base station position  60  and the candidate terminal station position  70  have grown densely. In addition, among such 6 timings, each of the timings q 4  and q 5  (i.e., measurement points in the range L in which the shield factor is low in  FIG.  30   ) is the autumn or winter timing, and thus is a timing when the leaves of the tree tr between the candidate base station position  60  and the candidate terminal station position  70  have fallen off. Further, among such 6 timings, each of the timings q 1  and q 6  (i.e., measurement points outside the range H in which the shield factor is high and outside the range L in which the shield factor is low in  FIG.  30   ) is a timing when the state of the leaves of the tree tr between the candidate base station position  60  and the candidate terminal station position  70  is between the aforementioned two states. 
     Therefore, the station deployment support apparatus  1   e  of the present embodiment can estimate that the shield factor is high in the spring and summer timings and the shield factor is low in the autumn and winter timings, for example. In addition, the station deployment support apparatus  1   e  can present to the user an estimation result indicating that the combination of the candidate base station position  60  and the candidate terminal station position  70 , which are the evaluation targets, is a combination of positions where the communication state is bad in the spring and summer but is good in the autumn and winter. Accordingly, the user can recognize that such a combination of the two stations is a combination that can be used only in a limited period of time. 
     Process of Sixth Embodiment 
     Hereinafter, an exemplary process of the station deployment support apparatus  1   e  will be described. 
       FIG.  31    is a flowchart illustrating a process flow of the station deployment support apparatus  1   e  of the sixth embodiment. 
     When a mobile object, such as a vehicle, having an MMS mounted thereon has traveled an identical place a plurality of times, the point group data processing unit  6   e  collects point group data obtained through each travel (step Sd 01 ). Then, the point group data processing unit  6   e  calculates the shield factor of the space between the candidate base station position  60  and the candidate terminal station position  70  based on point group data obtained through a given travel among the collected pieces of point group data (step Sd 02 ). 
     Then, the point group data processing unit  6   e  determines if the shield factor of the space between the candidate base station position  60  and the candidate terminal station position has been calculated based on point group data obtained through all travels (step Sd 03 ). If it is determined that there is another piece of point group data that has not been used for the calculation of the shield factor of the space between the candidate base station position  60  and the candidate terminal station position  70  (step Sd 03 , No), the point group data processing unit  6   e  reads the other piece of point group data that has not been used for the calculation (step Sd 04 ). Then, the point group data processing unit  6   e  repeats the processes of from step Sd 02  described above again. 
     Meanwhile, if the point group data processing unit  6   e  determines that the shield factor of the space between the candidate base station position  60  and the candidate terminal station position  70  has been calculated based on point group data obtained through all travels (step Sd 03 , Yes), the point group data processing unit  6   e  determines if all of the calculated shield factors are sufficiently low values (step Sd 05 ). It should be noted that the point group data processing unit  6   e  performs such determination based on whether all of the calculated shield factors are less than or equal to a predetermined value determined in advance by the user, for example. 
     If it is determined that all of the calculated shield factors are sufficiently low values (step Sd 05 , Yes), the station deployment support apparatus  1   e  presents to the user information indicating that the combination of the candidate base station position  60  and the candidate terminal station position  70 , which are the evaluation targets, is a combination where communication is always possible (step Sd 06 ). Accordingly, the processes illustrated in the flowchart of  FIG.  31    end. 
     Meanwhile, if it is determined that at least one of the calculated shield factors is not a sufficiently low value (step Sd 05 , No), the point group data processing unit  6   e  arranges (rearranges) the values of the shield factors, which are the plurality of calculation results, in order of time in which the pieces of point group data have been collected (step Sd 07 ). Then, the point group data processing unit  6   e  determines, based on the values of the shield factors arranged in order of time, if changes in the shield factors depend on the period (e.g., the season) (step Sd 08 ). It should be noted that the point group data processing unit  6   e  performs such determination based on whether it is possible to divide the whole period into a period in which the shield factors determined to be not low values (that is, determined to be high values) are arranged in succession, and a period in which the shield factors determined to be low values are arranged in succession, for example. 
     If it is determined that changes in the shield factors do not depend on the period (e.g., the season) (step Sd 08 , No), the point group data processing unit  6   e  changes the candidate base station position  60  and the candidate terminal station position  70  as the evaluation targets (step Sd 09 ). Then, the point the group data processing unit  6   e  repeats the processes of from step Sd 02  described above again. 
     If it is determined that changes in the shield factors depend on the period (e.g., the season) (step Sd 08 , Yes), the station deployment support apparatus  1   e  presents to the user information indicating the period (e.g., the season) in which the shield factor is low and communication is thus possible for the combination of the candidate base station position  60  and the candidate terminal station position  70  as the evaluation targets (step Sd 10 ). Accordingly, the processes illustrated in the flowchart of  FIG.  31    end. 
     Although the point group data processing unit  6   e  in the present embodiment is configured to determine if the combination of the candidate base station position  60  and the candidate terminal station position  70  is a combination where communication is possible based on the calculation result of shield factors, the present invention is not limited thereto. For example, the point group data processing unit  6   e  may be configured to determine if the combination of the candidate base station position  60  and the candidate terminal station position  70  is a combination where communication is possible based on the determination result of visibility. 
     As described above, the point group data processing unit  6   e  in the station deployment support apparatus  1   e  of the sixth embodiment performs, based on an identical candidate base station position  60 , an identical candidate terminal station position  70 , and a plurality of pieces of point group data obtained at different timings, a predetermined evaluation process (i.e., a visibility determination process or a shield factor calculation process) for each piece of the point group data. Then, the station deployment support apparatus  1   e  presents information obtained by associating the period (e.g., the season) with the communication state based on the result of the predetermined evaluation process obtained for each piece of the point group data (e.g., the result of comparison of a plurality of results of the predetermined evaluation process). The information about the communication state herein is information indicating the likelihood of fluctuation of the communication state (i.e., communication stability), for example, as described above. With such a configuration, the station deployment support apparatus  1   e  of the sixth embodiment can further improve the accuracy of station deployment design. 
     Although the aforementioned first to sixth embodiments have exemplarily illustrated millimeter-wave wireless communication as the wireless communication performed between a base station apparatus installed at the candidate base station position  60  and a terminal station apparatus installed at the candidate terminal station position  70 , communication other than the millimeter-wave wireless communication may also be performed, such as terrestrial digital communication, satellite radio communication, or communication for which UHF (Ultra High Frequency) is used. 
     In the aforementioned first to sixth embodiments, the determination processes are performed using an inequality sign or an inequality sign with an equality sign. However, the present invention is not limited to such embodiments, and the determination processes including determination conditions such as “if/whether . . . is greater than,” “if/whether . . . is less than,” “if/whether . . . is greater than or equal to,” and “if/whether . . . is less than or equal to” are only exemplary. Thus, depending on the way in which thresholds are determined, such determination processes may be replaced with determination processes including determination conditions such as “if/whether . . . is greater than or equal to,” “if/whether . . . is less than or equal to,” “if/whether . . . is greater than,” and “if/whether . . . is less than,” respectively. In addition, the thresholds used for such determination processes are also only exemplary. Thus, different thresholds may be applied to the respective determination processes. 
     The station deployment support apparatus  1  ( 1   a  to  1   e ) in each of the aforementioned embodiments may be implemented by a computer. In such a case, it is possible to implement the apparatus by recording a program for implementing the function of the apparatus on a computer readable recording medium and causing a computer system to read the program recorded on the recording medium and thus execute the program. It should be noted that the “computer system” herein includes hardware, such as an OS and peripheral devices. In addition, the “computer readable recording medium” refers to a portable medium, such as a flexible disk, a magneto-optical disk, ROM, or CD-ROM; or a storage device, such as a hard disk, incorporated in the computer system. Further, the “computer readable recording medium” may include a medium that dynamically holds a program for a short period of time, such as a communication line used for transmitting a program via a network like the Internet or a communication line like a telephone line; and a medium that holds a program for a given period of time, such as a volatile memory in a computer system that serves as a server or a client in the aforementioned case. In addition, the aforementioned program may be a program for implementing a part of the aforementioned function, or a program that can implement the aforementioned function by being combined with a program already recorded on the computer system. Alternatively, the aforementioned program may be a program implemented using a programmable logic device, such as an FPGA (Field Programmable Gate Array). 
     Although the embodiments of the invention have been described in detail with reference to the drawings, specific configurations are not limited thereto and thus include design that is within the spirit and scope of the invention. 
     INDUSTRIAL APPLICABILITY 
     When performing station deployment design for determining the places for installing a wireless base station and a wireless terminal station by utilizing point group data, it is possible to apply the point group data to the determination of visibility or the calculation of the shield factor for a space between a base station to be installed in an outdoor facility, such as a utility pole, and a terminal station to be installed on a wall surface of a building. 
     REFERENCE SIGNS LIST 
     
         
         
           
               1  ( 1   a  to  1   e ) Station deployment support apparatus 
               2  Design area designation unit 
               3  Candidate base station position extraction unit 
               4  Candidate terminal station position extraction unit 
               5  Determination processing unit 
               6  ( 6   a  to  6   e ) Point group data processing unit 
               7  Number-of-stations calculation unit 
               10  Operation processing unit 
               11  Map data storage unit 
               12  Facility data storage unit 
               13  Point group data storage unit 
               14  Travel trajectory data storage unit 
               15  Determination result storage unit 
               21  ( 21   a ,  21   b ) Positional relationship identification unit 
               22  ( 22   a ,  22   b ) Confidence coefficient identification unit 
               23  Determination processing unit 
               24  Shield factor calculation unit 
               25  Storage unit 
               26  Connecting line segment identification unit 
               28  Measurable range proportion calculation unit 
               29  Travel trajectory selection unit 
               30  Measurable range identification unit 
               31  Measurable range presence determination unit 
               32  Neighboring range identification unit 
               33  Neighboring range presence determination unit 
               34  Determination result storage unit 
               50  ( 50   a  to  50   f ) Travel trajectory 
               60  ( 60   b ,  60   d ) Candidate base station position 
               70  ( 70   b ,  70   d ,  70   x ,  70   y ) Candidate terminal station position 
               80  ( 80   b ,  80   d ) Fresnel zone 
               90  ( 90   x ,  90   y ) Connecting line segment 
               100  Neighboring range 
               110  ( 110   a ,  110   b ,  110   c ) Measurable range 
               200  ( 200   a  to  200   g ) Positional relationship configuration 
               300  ( 300   a ,  300   b ,  300   m ,  300   n ) Site 
               310  ( 310   a - 1 ,  310   b - 1 ) Building 
               320  ( 320   a - 1  to  320   a - 3 ) Tree 
               330  ( 330   b ) Signboard 
               400  Road 
               800 ,  801  Building 
               810  to  812  House 
               821  to  826  Utility pole 
               830  to  834  Base station (base station apparatus) 
               840  to  844  Terminal station (terminal station apparatus) 
               850  to  851  Telephone exchange station 
               900  to  901  Optical fiber