JP2014078884A - Position standardization system and method of controlling the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To appropriately select a base station for determining a position of a mobile terminal in a position standardization system.SOLUTION: Each of base stations 20 continuously receives a position standardization signal sent from a mobile terminal 30 at the same timing for a plurality of times. A server device 10, for each of the base stations 20, determines whether reception electric field intensity exceeds a preset first threshold value or not with respect to each of the position standardization signals for each time received by each of the base stations 20. A time sequentially pattern of a determination result is generated for each of the base stations 20 by arranging the determination result of the position standardization signal for each time of respective base stations 20 in a chronological order at which a position standardization signal 1 is received which is corresponding to each of the determination results. A base station 20 is selected which adopts the position standardization result of the mobile terminal 30 on the basis of each pattern of the base stations 20.

Description

  The present invention relates to a position location system and a control method for the position location system, and more particularly to a technique for appropriately performing handover in the position location system.

  In Patent Document 1, in a system for determining the direction, distance, position, etc. of a mobile terminal using a plurality of wireless markers, the result of determining the distance from the first wireless marker and the second wireless marker to the mobile terminal Based on the above, it is described that the handover from the service area of the first wireless marker to the service area of the second wireless marker is controlled.

  Non-Patent Document 1 discloses that a radio signal is transmitted from a plurality of antennas installed in a base station to a pedestrian's mobile terminal, and the relative position between the mobile terminal and the antenna is based on the phase difference of the radio signal transmitted from each antenna. A position locating system that obtains the current position of a pedestrian from the obtained relative position (direction, distance) and the absolute position of the base station is disclosed.

JP 2008-199589 A

Takenori Takeuchi, Kiminori Kono, Minoru Kono, “Development of a location detection system using the 2.4 GHz band”, The 56th Annual Conference of the Chugoku Branch of the Institute of Electrical and Information Engineering, 2005

  In the positioning system disclosed in Non-Patent Document 1, for example, when an antenna having a directivity range of 90 ° is used as an antenna of a base station and a mobile terminal, the range in which positioning can be performed is the ground height of the base station. If the ground height of the mobile terminal is h, a circular area with a radius of Hh is obtained.

  For this reason, in order to stably maintain the positioning accuracy for mobile terminals that move over a wide area, multiple base stations are installed so that the entire area is covered, and mobile terminals can be moved. Accordingly, it is necessary to realize a mechanism for sequentially switching base stations (hereinafter also referred to as handover).

  Here, as a characteristic of the received electric field strength of the position location signal, when the mobile terminal is within the area of the base station (the range in which the base station is responsible for position location), the position location signal is directly transmitted from the mobile terminal to the base station. As a result, the received electric field strength basically increases. Conversely, if the mobile terminal is outside the base station area, the positioning signal transmitted from the mobile terminal is reflected on the ceiling or floor and reaches the base station as a reflected wave (indirect wave). The received electric field strength is smaller than in the case of The received electric field strength is substantially constant within the area, but slightly decreases near the boundary of the area and greatly decreases outside the area.

  On the other hand, the level of positioning accuracy is not strictly correlated with the received electric field strength, but shows a similar tendency of the received electric field strength. For this reason, in order to maintain the accuracy of positioning, it is effective to preferentially select a base station having a large received electric field strength as much as possible.

  However, when priority is given to selecting a base station having a high received electric field strength, there are the following problems. For example, when a certain base station is affected by multipath, the received electric field strength may decrease significantly in a spot manner even within an area. In that case, simply based on the comparison result of the received electric field strength. If a base station is selected, another base station having a received electric field strength larger than the received electric field strength at the time of spot decrease may be selected, and the positioning accuracy may be significantly reduced. .

  That is, even when the received electric field strength decreases in a spot manner, it is usually possible to maintain sufficient accuracy by the positioning signal received with a high received electric field strength before and after (for example, the positioning algorithm is a predetermined algorithm). When it is configured to use the average value of the positioning result by each of the positioning signals received the number of times, or it does not adopt the positioning signal with low received electric field strength to the positioning when calculating the average If the base station is switched only by the comparison of the received electric field strength, the positioning accuracy may be significantly reduced.

  The present invention has been made in view of such a background, and provides a position location system and a position location system control method capable of appropriately performing handover so that the accuracy of position location is maintained. The purpose is to do.

  In order to achieve the above object, one aspect of the present invention provides a plurality of antennas arranged adjacent to each other, which receive a location signal, which is a radio signal used for locating the location of the mobile terminal, transmitted from the mobile terminal. And a server device that is communicably connected to each of the plurality of base stations, and the base station is based on a phase difference Δθ of the positioning signal received by each of the antennas. , A location system that obtains a direction ΔΦ in which the mobile terminal exists as seen from the base station, and performs location of the mobile terminal based on the obtained direction ΔΦ, each of the base stations being the mobile terminal The position determination signal sent from the base station is received a plurality of times continuously at the same timing, and the server device receives each of the position determination signals received each time for each of the base stations. It is determined whether or not the received electric field strength exceeds a preset first threshold value, and the determination results of the respective position determination signals of the individual base stations are used as the position determination corresponding to each of the determination results. A time-series pattern of the determination result is generated for each of the base stations by arranging the signals in the order of reception time, and the position determination result of the mobile terminal is adopted based on the pattern of each of the base stations. The base station to be selected is selected.

  According to the present invention, handover can be appropriately performed so that the accuracy of position location is maintained.

  Another one of the present invention is the position location system, wherein the server apparatus is configured such that, in one of the base stations, the received electric field strength in the pattern of the base station is equal to or less than the first threshold value. The determination result indicating that the ratio of the determination result indicating that the pattern is equal to or smaller than the second threshold and the pattern is equal to or smaller than the first threshold follows the determination result indicating that the first threshold is exceeded. If the base station is included in the base station, the base station has a larger proportion of the determination result that the received electric field strength of the pattern is equal to or lower than the first threshold value than the base station. Priority is given to selecting the base station that adopts the result of positioning of the mobile terminal.

  According to the present invention, handover is not performed when the received electric field strength is reduced in spot, so that handover is performed carelessly and the positioning accuracy is lowered despite the spot decrease. Can be prevented.

  Another one of the present invention is the position location system, wherein the server device is configured with the determination result that all of the patterns have the received electric field strength exceeding the first threshold value. In the base station, the determination result that the received electric field strength exceeds the first threshold and the determination result that the received electric field strength is less than or equal to the first threshold are included in the pattern. The mobile station is selected as the base station that adopts the location determination result of the mobile terminal in preference to the base stations that are mixed.

  According to the present invention, it is possible to obtain a highly accurate positioning result determined by a base station in which a mobile terminal is always present in the area.

  Another one of the present invention is the position locating system, wherein the server device includes the determination result that the received electric field strength exceeds the first threshold value and the received electric field in the pattern. When there are a plurality of the base stations that include the same result as the determination result indicating that the strength is equal to or less than the first threshold, the reception is received at the reception time for each reception time of the positioning signal. The determination result of the position location signal adopts the location result of the mobile terminal for the base station that has transmitted the position location signal, which is the content that the received electric field strength exceeds the first threshold value. The base station to be selected is selected.

  ADVANTAGE OF THE INVENTION According to this invention, when a mobile terminal exists in the vicinity of the boundary of the area of a certain base station, and it is also the vicinity of the boundary of the area of another base station, it can aim at maintenance of a positioning accuracy.

  In addition, the subject which this application discloses, and its solution method are clarified by the column of the form for inventing, and drawing.

  According to the present invention, handover can be appropriately performed so that the accuracy of position location is maintained.

1 is a diagram showing a schematic configuration of a position location system 1. FIG. 2 is a diagram illustrating main hardware of a server device 10. FIG. 3 is a diagram illustrating main functions of the server device 10. FIG. It is a figure which shows an example of the time-sequential pattern of a determination result. It is a figure which shows an example of the time-sequential pattern of a determination result. It is a figure which shows an example of the time-sequential pattern of a determination result. It is a figure which shows an example of the time-sequential pattern of a determination result. 2 is a diagram illustrating main hardware of a mobile terminal 30. FIG. 2 is a diagram illustrating main functions of a mobile terminal 30. FIG. 2 is a diagram illustrating main hardware of a base station 20. FIG. 2 is a diagram illustrating main functions of a base station 20. FIG. It is a figure which shows an example of the position determination signal 1200. FIG. FIG. 2 is a diagram showing a positional relationship between a base station 20 and a mobile terminal 30. FIG. 2 is a diagram illustrating the configuration of four antennas 25a to 25d provided in a base station 20. It is a figure explaining the positional relationship of the base station 20 and the mobile terminal 30. FIG. It is a flowchart explaining handover processing S1600.

  FIG. 1 shows a schematic configuration of a position location system 1 described as an embodiment. The position location system 1 is, for example, a system that monitors the current position of a moving body 3 (people (pedestrians, etc.), vehicles, transport carts, forklifts, luggage, cargo, etc.), and safety of the moving bodies 3 (people, vehicles, etc.). A system for securing, a system for providing guidance to the destination for the moving body 3 (people, vehicles, etc.), a system for providing information around the current location to the moving body 3 (people, vehicles, etc.), The present invention can be widely applied to a system that performs evacuation guidance in a building district, a system that manages the flow of luggage and cargo in warehouses and factories, and a guidance system such as robots and automatic conveyance vehicles in factories.

  The position location system 1 is carried by a server device 10 provided in a management center, a monitoring center, or the like of the position location system 1, a plurality of base stations 20 provided in various locations in an area where the position location system 1 is applied, and a mobile unit 3. Alternatively, one or more mobile terminals 30 to be attached are included.

  The base station 20 is provided at a predetermined height position from the plane on which the moving body 3 moves. For example, when the location system 1 is used indoors, the base station 20 is provided on a pillar or a wall of a building, for example. Further, for example, when the position location system 1 is used outdoors, the base station 20 is provided, for example, on a utility pole or a steel tower.

  The base station 20 and the mobile terminal 30 communicate with the server device 10 via the communication network 5. The communication network 5 is a wired or wireless communication means such as a dedicated line, a public line, a LAN (Local Area Network), a WAN (Wide Area Network), and the Internet.

  FIG. 2 shows the main hardware of the server device 10. As shown in the figure, the server device 10 includes a central processing unit 11 (CPU, MPU, etc.), a storage device 12 (semiconductor memory (RAM, ROM, NVRAM, etc.), a hard disk device, etc.), and an input device 13 (keyboard and mouse). ), A display device 14 (liquid crystal display, etc.), a communication interface 15 (NIC (Network Interface Card), wireless communication module, etc.) for connecting the server device 10 to the communication network 5 and the like. On the display device 14, for example, information indicating the current position and moving direction of the moving body 3 is displayed in real time. As shown in the figure, each component of the server device 10 is connected to be communicable with each other via a bus 18.

  FIG. 3 shows main functions of the server device 10. As shown in the figure, the server device 10 includes an information collecting unit 101, an information providing unit 102, a setting information storage unit 103, and a handover control unit 104. These functions are realized by hardware included in the server device 10 or when the central processing unit 11 of the server device 10 reads and executes a program stored in the storage device 12.

  The information collection unit 101 receives the received electric field strength of a positioning signal 1200 (to be described later) sent from each base station 20 or the mobile terminal 30 as needed, and the result of the positioning performed by each base station 20 (the current position of the mobile terminal 30). ) And the like are received and managed (stored). The information collecting unit 101 manages the received information with information (hereinafter referred to as a base station ID) indicating from which base station 20 the information is transmitted.

  For example, the information providing unit 102 monitors the base station 20 or the mobile terminal 30 with monitoring information such as the current position and moving direction of the moving body 3, information about ensuring the safety of the moving body 3, route guidance information, and guidance to the destination. Information such as information and geographic information around the current location is provided as needed.

  The setting information storage unit 103 stores, for example, information (latitude, longitude, installation height, etc.) indicating the position where the base station 20 is installed as setting information.

  The handover control unit 104 performs control related to handover of the mobile terminal 30 (switching of the base station 20 in charge of position location described later for the mobile terminal 30). As shown in the figure, the handover control unit 104 includes an area inside / outside determination unit 1041, a pattern generation storage unit 1042, and a base station selection control unit 1043.

  Among these, the area inside / outside determination unit 1041 compares the received electric field strength of the position location signal 1200 received from the base station 20 with a preset threshold value (hereinafter also referred to as a first threshold value), thereby determining the position location signal. The mobile terminal 30 that has transmitted 1200 determines whether or not the base station 20 exists in an area that is responsible for the location of the mobile terminal 30.

  The pattern generation storage unit 1042 is configured so that the base station 20 determines a plurality of position location signals 1200 received from the mobile terminal 30 a plurality of times by the area inside / outside determination unit 1041 (the mobile terminal 30 has its base Time series of the determination results for individual base stations by arranging the determination results of whether or not they exist in the area of the station 20 in the order of time of receiving the position location signals 1200 corresponding to each of the determination results. A typical pattern is generated and stored in association with the base station ID.

  Here, the base station 20 continuously receives the positioning signal 1200 multiple times, each reception time interval and the number of continuous receptions are, for example, movement modes such as the moving speed of the mobile terminal 30. In consideration of the installation interval of the base station 20, the influence of multipath, and the like, the base station 20 is set to be appropriately selected so that the accuracy of the positioning is maintained.

  In the following description, when the determination result is switched from “in area” to “out of area”, or the determination result is switched from “out of area” to “in area” is referred to as a state change. is there.

  FIG. 4 shows an example of a time-series pattern of determination results generated by the pattern generation unit 1042. In the figure, two patterns (pattern A) generated for each base station 20 when each of the two base stations 20 (base stations A and B) receives the positioning signal 1200 continuously four times. , Pattern B). Each pattern includes contents in which the determination results for each of the location signals 1200 (first to fourth) received individually from the mobile terminal 30 by the two base stations 20 are arranged in chronological order.

  Returning to FIG. 3, the base station selection control unit 1043 selects the base station 20 that adopts the position determination result of the mobile terminal 30 based on the time-series pattern of the determination result generated for each of the base stations 20. . The information providing unit 102 of the server device 10 is based on the position of the mobile terminal 30 determined by the selected base station 20, for example, monitoring information such as the current position or moving direction of the moving body 3, and ensuring the safety of the moving body 3. It provides information such as information, route guidance information, guidance information to the destination, and geographical information around the current position.

  Subsequently, some examples of the selection method of the base station 20 by the base station selection control unit 1043 are shown.

  For example, as shown in FIG. 5, in one of the base stations 20 (base station A), the ratio of the determination result that the received electric field strength is equal to or lower than the first threshold in the pattern of the base station 20 is the second. A determination result indicating that the first threshold value is exceeded is followed by a determination result indicating that the pattern is less than or equal to a threshold value (threshold value for determining whether the state change is spot-like) and the pattern is less than or equal to the first threshold value. When the position determination signal 1200 is included, for example, during the reception period of the position determination signal 1200, the server apparatus 10 performs position determination following the position determination signal 1200 for the fourth time after receiving the position determination signal 1200 for the first time. During the period until the signal 1200 is received), the base station 20 has a larger proportion of the determination result that the received electric field strength of the pattern is equal to or lower than the first threshold than the base station 20. 0 with priority over (base station B), is selected as a base station 20 employing the results of the position location of the mobile terminal 30.

  In this example, for the pattern A of the base station A, only the third determination result is “out of area” among the four determination results, but this is spot-like due to the influence of multipath or the like. The mobile terminal 30 is assumed to have always been present in the area during the reception period of the position location signal 1200. For this reason, if the base station B is selected as the base station 20 that adopts the location determination result of the mobile terminal 30 in such a case, the accuracy of the location determination is unnecessarily reduced. Therefore, in this case, the server apparatus 10 causes the received electric field intensity to decrease only in a spot manner as compared with the base station B corresponding to the pattern B in which the ratio of the determination result “out of area” as a whole is large as described above. The base station A is preferentially selected as the base station 20 that adopts the result of the positioning of the mobile terminal 30.

  If the time-series pattern of the determination result has the contents shown in FIG. 6, for example, during the reception period of the position location signal 1200, the server device 10 has the received electric field strength exceeding the first threshold value for all the patterns. A determination result that the received electric field strength exceeds the first threshold in the pattern of the base station 20 (in this example, the base station B) configured with the determination result And a determination result indicating that the received electric field strength is equal to or less than the first threshold (a state change occurs) base station 20 (base station A in this example) (in this case, mobile terminal 30 The base station 20 is selected as a base station 20 that adopts the location determination result of the mobile terminal 30 in preference to the vicinity of the boundary of the area of the base station 20 (which is likely to exist in the vicinity of the boundary, including the boundary). According to this, the server apparatus 10 has been able to stably receive the position location signal 1200 (the mobile terminal 30 is always present in the area), and a highly accurate position location result determined by the base station 20. Can be obtained.

  When the time-series pattern of the determination result has the contents shown in FIG. 7, that is, the determination result that the received electric field strength exceeds the first threshold and the received electric field strength is less than or equal to the first threshold. When there are a plurality of base stations 20 that are included in the same ratio with the determination result to the effect (in this case, there is a high possibility that the mobile terminal 30 exists near the boundary of the area of each base station) For each reception time of the position location signal 1200, the server device 10 determines the position location whose content of the determination result of the position location signal 1200 received at the time of reception is that the received electric field strength exceeds the first threshold. The base station 20 that has transmitted the signal 1200 is selected as the base station 20 that adopts the result of the positioning of the mobile terminal 30.

  Specifically, the server device 10 (base station selection control unit 1043), for example, during the reception period of the first and second position location signals 1200 (the third time after receiving the first position location signal 1200). For the period until the position location signal 1200 is received), the base station A is selected as the base station 20 that adopts the position location result of the mobile terminal 30, and during the third and fourth times of the position location signal 1200 reception period ( For the period from when the third positioning signal 1200 is received until the fourth positioning signal 1200 is received, the base station B adopts the positioning result of the mobile terminal 30. Select as the base station 20.

  In the pattern as shown in the figure, for example, the mobile terminal 30 exists near the boundary of the area of the base station A, and exists near the boundary of the area of the base station B. Get in case. By causing the server device 10 to select the base station 20 by the above method, the positioning accuracy can be maintained even when the mobile terminal 30 is in such a situation.

  FIG. 8 shows main hardware of the mobile terminal 30. As shown in the figure, the mobile terminal 30 includes a central processing unit 31 (CPU, MPU, etc.), a storage device 32 (semiconductor memory (RAM, ROM, NVRAM, etc.), a hard disk device, etc.), and a position location signal 1200 described later. Wireless communication interface 33 (NIC, wireless communication module, etc.) that performs transmission and wireless communication with other devices, antenna 34 used for wireless communication performed by wireless communication interface 33, input device 35 (touch panel, operation buttons) Etc.) and a display device 36 (liquid crystal display, organic EL display, etc.). These components are connected to each other via a bus 39 so as to communicate with each other.

  The antenna 34 is a directional antenna, for example. The antenna 34 may be provided integrally with the housing of the mobile terminal 30 or may be provided separately from the housing of the mobile terminal 30. When the mobile terminal 30 is used indoors where an obstacle such as a wall exists, the antenna 34 is preferably a circularly polarized directional antenna. The polarization plane of the circularly polarized reflected wave (or standing wave) is inverted when reflected by an obstacle such as a wall, but the reflected wave or standing wave is effective by using a circularly polarized directional antenna. Can be attenuated.

  FIG. 9 shows main functions provided in the mobile terminal 30. As shown in the figure, the mobile terminal 30 includes a position location signal transmission unit 301, an information transmission / reception unit 302, and an information display unit 303. These functions are realized by hardware included in the mobile terminal 30 or when the central processing unit 31 of the mobile terminal 30 reads out and executes a program stored in the storage device 32.

  Among the functions described above, the position determination signal transmission unit 301 transmits a wireless signal (hereinafter referred to as a position determination signal 1200) used for position determination of the mobile terminal 30 from the wireless communication interface 33. The position location signal transmission unit 301 transmits the position location signal 1200 repeatedly (for example, periodically) at short time intervals, for example.

  The information transmission / reception unit 302 communicates with the server device 10 or the base station 20 by wireless communication using the wireless communication interface 33 or wired communication using the communication network 5, and receives (downloads) information to be presented to the mobile unit 3. 10 or transmission (upload) of various information used in the base station 20 is performed. The information display unit 303 outputs information to be presented to a person or the like to the display device 36.

  FIG. 10 shows the main hardware of the base station 20. As shown in the figure, the base station 20 includes a central processing unit 21 (CPU, MPU, etc.), a storage device 22 (semiconductor memory (RAM, ROM, NVRAM, etc.), hard disk device, etc.), and a base station 20 connected to the communication network 5. A communication interface 23 (NIC, wireless communication module, etc.) for connecting to the wireless communication interface, a wireless communication interface 24 (wireless communication module, etc.) for performing wireless communication, a plurality of antennas 25, and an antenna changeover switch 26. These components are communicably connected via a bus 28.

  The central processing unit 21 implements various functions of the base station 20 by reading and executing a program stored in the storage device 22. The wireless communication interface 24 receives the position location signal 1200 transmitted from the mobile terminal 30.

  The antennas 25 are all directional antennas. The antenna changeover switch 26 sequentially selects any one of the plurality of antennas 25 and connects the antennas 25 to the wireless communication interface 24. When the position location system 1 is used indoors where obstacles such as walls exist, it is preferable to use a circularly polarized directional antenna as the antenna 25. Since the plane of polarization of the circularly polarized reflected wave (or standing wave) is inverted when reflected by a wall or the like, the reflected wave (or standing wave) is effectively used by using a circularly polarized directional antenna as the antenna 25. This is because it can be attenuated.

  FIG. 11 shows main functions of the base station 20. As shown in the figure, the base station 20 includes a communication processing unit 201, a position location signal receiving unit 202, a setting information storage unit 203, and a position location unit 204. Note that these functions are realized by hardware included in the base station 20 or by the central processing unit 21 of the base station 20 reading and executing a program stored in the storage device 22.

  The communication processing unit 201 controls the communication interface 23 and the wireless communication interface 24 to transmit or receive data between the mobile terminal 30, the server device 10, and another base station 20.

  The location signal receiving unit 202 controls the wireless communication interface 24 and the antenna changeover switch 26 to receive the location signal 1200 transmitted from the mobile terminal 30.

  The setting information storage unit 203 stores the setting information described above (for example, information indicating the current position of the base station 20 (latitude, longitude, height (height H described later), etc.)).

  The location determination unit 204 determines the current location of the mobile terminal 30 managed by the responsible terminal information described later based on the location determination signal 1200. The position locating unit 204 changes the state of the moving object 3 when the position of the moving object 3 (the mobile terminal 30) is determined (for example, when a position determination signal 1200 is received and a preset time arrives). When the time is reached, the current position of the mobile terminal 30 is determined.

  Further, the position location unit 204 continuously receives the position location signals 1200 sent from the mobile terminal 30 at the same timing (synchronized timing) as other base stations 20 a plurality of times. The synchronization control in this case is performed, for example, by instructing the base stations 20 from the server device 10 all at once or by communicating between the base stations 20. Further, each base station 20 may be provided with a time measuring device in which accurate time adjustment is performed, and the synchronization control may be performed based on the time measuring device.

  The current position of the mobile terminal 30 determined by the position determination unit 204 is transmitted to the server device 10 and the mobile terminal 30 as needed by the communication processing unit 201, and is used for various purposes by the server device 10 and the mobile terminal 30.

<Positioning principle>
Next, a mechanism for locating the position of the mobile terminal 30 performed by the position locating system 1 will be described. As a premise for the following description, it is assumed that the mobile terminal 30 repeatedly transmits the position location signal 1200 at a sufficiently short time interval. In addition, the base station 20 receives the positioning signal 1200 while switching a plurality of antennas 25 (here, four antennas 25a to 25d as an example) with a sufficiently short period.

  FIG. 12 shows an example of a position location signal 1200 transmitted from the antenna 34 of the mobile terminal 30. As shown in the figure, the position location signal 1200 includes a control signal 1211, a measurement signal 1212, and terminal information 1213.

  The control signal 1211 includes a modulated wave and various control signals. The measurement signal 1212 is an unmodulated wave of about several milliseconds (for example, a signal used for detecting the direction in which the mobile terminal 30 is present with respect to the base station 20 and the relative distance to the mobile terminal 30 with respect to the base station 20 (for example, 2048 chips). ) Spread code)). The terminal information 1213 includes the terminal ID of the mobile terminal 30.

  FIG. 13 shows the positional relationship between the base station 20 and the mobile terminal 30. As shown in the figure, the base station 20 is fixed at a height H (m) from the plane π on which the moving body 3 moves. In addition, the mobile terminal 30 is present at a height h (m) from the plane π. In addition, on the plane π, the linear distance from directly below the base station 20 to directly below the mobile terminal 30 is L (m).

  FIG. 14 shows a plurality of antennas 25 (antennas 25a to 25d) provided in the base station 20. As shown in the figure, each of the four antennas 25a to 25d has one wavelength of the positioning signal 1200 (for example, a wavelength λ = 12.5 cm when a 2.4 GHz band radio wave is used as the positioning signal 1200). Adjacently arranged in a substantially square shape with a space of the following (for example, 3 cm). Each of the four antennas 25a to 25d is a directional antenna (for example, a circularly polarized directional antenna), and the directivity direction thereof is obliquely downward.

In the figure, if the angle between the horizontal direction at the height of the antenna 25 and the direction of the mobile terminal 30 with respect to the antenna 25 is α, there is the following relationship between them.
α = arcTan (D (m) / L (m)) = arcSin (ΔL (cm) / 3 (cm))
... Formula 1

  ΔL (cm) is a difference in propagation path length between the two specific antennas 25 and the mobile terminal 30 among the antennas 25a to 25d constituting the antenna 25 (hereinafter also referred to as a route difference). .)

Here, among the four antennas 25a to 25d, if the phase difference of the positioning signal 1200 received by two specific antennas 25 is Δθ, the following relationship is established.
ΔL (cm) = Δθ / (2π / λ (cm)) Equation 2

Here, for example, when the positioning signal 1200 is a 2.4 GHz band radio wave (wavelength λ = 12.5 (cm)), α = arcSin (Δθ / π) Equation 3
Therefore, within the measurable range (−π / 2 <Δθ <π / 2) (directivity angle of antenna 25 (half-value width)), α can be calculated from the phase difference Δθ (radian). The direction α in which 20 is present can be specified.

As shown in FIG. 15, the height from the plane π of the antenna 25 of the base station 20 is H, the height from the plane π of the mobile terminal 30 is h, and the position on the plane π immediately below the base station 20 is the origin. Is set on the plane π, and the angle formed by the direction of the mobile terminal 30 viewed from the base station 20 and the X axis, which is obtained from the direction α, is ΔΦ (x), from the direction α. If the angle formed by the direction of the mobile terminal 30 viewed from the base station 20 and the Y axis is ΔΦ (y), the positions Δd (x) and Δd (y) of the mobile terminal 30 with respect to the origin are obtained from the following equations. be able to.
Δd (x) = (H−h) × Tan (ΔΦ (x)) Equation 4
Δd (y) = (H−h) × Tan (ΔΦ (y)) Equation 5

If the origin (X1, Y1) is a point where the perpendicular line drawn from the base station 20 to the plane π intersects the plane π, the current position (Xx, Yy) of the mobile terminal 30 can be obtained from the following equation.
Xx = X1 + Δd (x) Expression 6
Yy = Y1 + Δd (y) Expression 7

Assuming that the position of the mobile terminal 30 is d and the direction in which the mobile terminal 30 is present as seen from the base station 20 obtained by position determination is ΔΦ, the equations 4 and 5 do not specify the coordinate system, It can be expressed as
d = (H−h) × tan ΔΦ Equation 8

  The principle of positioning described above is described in detail in, for example, Japanese Patent Application Laid-Open Nos. 2004-184078, 2005-351877, 2005-351878, and 2006-23261. ing.

= Handover =
Next, control related to handover will be specifically described. FIG. 16 is a flowchart for explaining an example of processing (hereinafter referred to as handover processing S1600) performed by the server device 10 regarding handover control. Hereinafter, it will be described with reference to FIG.

  The server device 10 monitors in real time whether or not the timing for performing the handover control has arrived for each of the mobile terminals 30 that are the targets of position location (S1611). Note that the above timing is, for example, when a predetermined time elapses (for example, periodically), if any of the base stations 20 enters the vicinity of the boundary of the area of the base station 20 where the mobile terminal 30 is currently located. This occurs when a handover execution request is received from the mobile terminal 30.

  When the server device 10 detects that the above timing has arrived (S1611: YES), the server device 10 continuously receives a plurality of position location signals 1200 sent from the mobile terminal 30 to the plurality of base stations 20 a plurality of times. An instruction is transmitted (S1612). In addition, the server apparatus 10 selects the some base station 20 which transmits the said instruction | indication based on the past movement history of the mobile terminal 30, for example.

  When each base station 20 receives the above instruction, the base station 20 receives the positioning signal 1200 sent from the mobile terminal 30 a plurality of times in succession in time, the received electric field strength of each received positioning signal 1200, The location determination result of the mobile terminal 30 based on the received location determination signal 1200 is transmitted to the server device 10. Note that the timing at which each base station 20 receives the position location signal 1200 in each time is synchronized.

  When the server apparatus 10 receives the received electric field strength and the positioning result of each time sent from each base station 20, the server apparatus 10 stores them in association with the base station ID (S1613).

  Subsequently, the server device 10 determines whether or not the received electric field strength of each time the positioning signal 1200 of each base station 20 exceeds a preset threshold (“in area” or “out of area”), For each base station 20, the determination results of the respective position determination signals 1200 are arranged in the order of reception time of the position determination signals 1200 corresponding to the determination results, so that the determination results of the individual base stations 20 are time-series. A pattern is generated (S1614).

  Subsequently, the server device 10 selects the base station 20 that adopts the result of the location of the mobile terminal 30 based on the time-series pattern of each determination result of the base station 20 (S1615). Specifically, the server apparatus 10 selects the base station 20 as follows.

  That is, in principle, the server apparatus 10 determines the location of the mobile terminal 30 in preference to the base stations 20 whose determination results constituting the pattern are all “in the area” over other base stations 20 that are not. The base station 20 that adopts the result is selected.

  In addition, for example, in one of the base stations 20, the server apparatus 10 has a ratio of a determination result that the received electric field strength is equal to or lower than the first threshold in the pattern of the base station 20 is equal to or lower than the second threshold, and In a case where the determination result indicating that the first threshold is exceeded is included in the pattern, the determination result indicating that the pattern exceeds the first threshold is included in the pattern. The base station 20 that adopts the result of the positioning of the mobile terminal 30 is selected in preference to the other base stations 20 that have a large proportion of the determination result that the received electric field strength of the pattern is equal to or less than the first threshold ( This corresponds to the case of FIG. 5 described above).

  In addition, the server apparatus 10 uses the base station 20 configured with a determination result indicating that the received electric field strength exceeds the first threshold for all of the patterns, and the received electric field strength exceeds the first threshold for the pattern. Selected as a base station 20 that adopts the location determination result of the mobile terminal 30 in preference to the base station 20 in which the determination result of the effect and the determination result that the received electric field strength is equal to or less than the first threshold are mixed. (Corresponding to the case of FIG. 6 described above).

  The server apparatus 10 also includes a base station in which the determination result that the received electric field strength exceeds the first threshold and the determination result that the received electric field strength is equal to or less than the first threshold are included in the pattern at the same rate. When there are a plurality of positions 20, the determination result of the position location signal 1200 received at each reception time of the position location signal 1200 indicates that the received electric field strength exceeds the first threshold. The base station 20 that has transmitted the position location signal 1200 is selected as the base station 20 that adopts the location result of the mobile terminal 30 (corresponding to the case of FIG. 7 described above).

  Subsequently, the server device 10 employs the position determination result of the base station 20 selected at each time during the reception period of the position determination signal 1200 as information indicating the position of the mobile terminal 30 at each time point (S1616). Thereafter, the process returns to S1611.

  As described above, according to the position location system 1 of the present embodiment, the base station 20 that adopts the position location result of the mobile terminal 30 is appropriately selected so that the accuracy of the position location is ensured. And handover can be appropriately performed.

  In addition, since handover is not performed when the received electric field strength is spot-like, it is possible to prevent the location determination accuracy from being lowered due to inadvertent handover despite the spot-like decline. be able to.

  In addition, the server device 10 includes the base station 20 that is configured with a determination result indicating that the received electric field strength exceeds the first threshold value (no state change has occurred) in all the patterns, and the received electric field strength is in the pattern. The mobile terminal 30 has priority over the base station 20 in which the determination result that the first threshold value is exceeded and the determination result that the received electric field strength is equal to or less than the first threshold value are mixed (a state change has occurred). Therefore, it is possible to obtain a highly accurate positioning result determined by the base station 20 in which the mobile terminal 30 always exists in the area.

  The server apparatus 10 also includes a base station in which the determination result that the received electric field strength exceeds the first threshold and the determination result that the received electric field strength is equal to or less than the first threshold are included in the pattern at the same rate. When there are a plurality of positions 20, the determination result of the position location signal 1200 received at each reception time of the position location signal 1200 indicates that the received electric field strength exceeds the first threshold. Since the base station 20 that has transmitted the position location signal 1200 is selected as the base station 20 that adopts the result of the location of the mobile terminal 30, the mobile terminal 30 exists near the boundary of the area of the base station A, And even when it exists in the position which is also the boundary vicinity of the area of the base station B, the positioning accuracy can be maintained.

  As mentioned above, although embodiment of this invention was described in detail, the above description is for making an understanding of this invention easy, and does not limit this invention. It goes without saying that the present invention can be changed and improved without departing from the gist thereof, and that the present invention includes equivalents thereof.

  For example, one or more base stations 10 may realize the function of the server device 10.

  Further, in the above embodiment, the positioning signal 1200 is transmitted from the antenna 34 of the mobile terminal 30 and received by the antenna 25 of the base station 20 so that the base station 20 performs the positioning. On the contrary, the positioning signal 1200 may be transmitted from the base station 20, and the mobile terminal 30 may receive the positioning signal 1200 from the base station 20 and perform its own positioning at the mobile terminal 30. . Further, information indicating the position of the mobile terminal 30 determined by itself may be provided (transmitted) from the mobile terminal 30 to the server device 10 or the base station 20 via the communication network 5 or wireless communication.

  For example, the mobile terminal 30 may function as an active or passive RFID tag. In this case, a signal corresponding to the position location signal 1200 may be transmitted to or received from the base station 20 spontaneously or passively from an antenna coil included in the RFID tag by electromagnetic induction.

DESCRIPTION OF SYMBOLS 1 Location system 3 Mobile body 10 Server apparatus 104 Handover control part 1041 Area inside / outside determination part 1042 Pattern generation memory | storage part 1043 Base station selection control part 1200 Position location signal 20 Base station 204 Position location part S1600 Handover process

Claims (8)

A plurality of base stations having a plurality of antennas arranged adjacent to each other, receiving a positioning signal that is a radio signal used for positioning of the position of the mobile terminal transmitted from the mobile terminal;
A server device communicably connected to each of the plurality of base stations,
The base station obtains a direction ΔΦ in which the mobile terminal exists as seen from the base station based on the phase difference Δθ of the positioning signal received by each of the antennas, and moves based on the obtained direction ΔΦ. A location system for positioning a terminal,
Each of the base stations receives the positioning signal sent from the mobile terminal a plurality of times continuously at the same timing,
The server device
For each of the base stations, for each of the positioning signals received each time, it is determined whether the received electric field strength exceeds a preset first threshold value, and the respective times of each of the base stations By arranging the determination results of the position location signals in the order of reception of the position location signals corresponding to each of the determination results, a time-sequential pattern of the determination results is generated for each of the base stations,
Based on the respective patterns of the base stations, the base station that adopts the result of positioning of the mobile terminal is selected. The location system according to claim 1,
The server device has a ratio of the determination result that the received electric field strength is equal to or lower than the first threshold in the pattern of the base station in one of the base stations is equal to or lower than a second threshold, and If the determination result that the pattern is less than or equal to the first threshold is followed by the determination result that the pattern exceeds the first threshold, the base station is more than the base station. The base that adopts the result of positioning of the mobile terminal in preference to the other base stations that have a large proportion of the determination result that the received electric field strength of the pattern is equal to or less than the first threshold. A location system characterized by being selected as a station. The location system according to claim 1 or 2,
The server device includes the base station configured with the determination result that all the patterns have the received electric field strength exceeding the first threshold, and the received electric field strength is the first pattern in the pattern. Positioning of the mobile terminal is prioritized over the base station in which the determination result that the threshold value exceeds 1 and the determination result that the received electric field strength is equal to or less than the first threshold are mixed. A location system that selects the base station that adopts the result of The position location system according to any one of claims 1 to 3,
In the server device, the determination result that the received electric field strength exceeds the first threshold and the determination result that the received electric field strength is less than or equal to the first threshold are the same rate in the pattern. When there are a plurality of the included base stations, for each reception time of the positioning signal, the determination result of the positioning signal received at the reception time indicates that the received electric field strength is the first threshold value. A location system that selects the base station that has transmitted the location signal, which indicates that the location has been exceeded, as the base station that adopts the location result of the mobile terminal. A plurality of base stations having a plurality of antennas arranged adjacent to each other, receiving a positioning signal that is a radio signal used for positioning of the position of the mobile terminal transmitted from the mobile terminal;
A server device communicably connected to each of the plurality of base stations,
The base station obtains a direction ΔΦ in which the mobile terminal exists as seen from the base station based on the phase difference Δθ of the positioning signal received by each of the antennas, and moves based on the obtained direction ΔΦ. A method for controlling a location system that performs terminal location,
Each of the base stations receives the position location signal sent from the mobile terminal continuously at the same timing multiple times,
The server device is
For each of the base stations, for each of the positioning signals received each time, it is determined whether the received electric field strength exceeds a preset first threshold value, and the respective times of each of the base stations By arranging the determination results of the position location signals in the order of reception of the position location signals corresponding to each of the determination results, a time-sequential pattern of the determination results is generated for each of the base stations,
A control method for a position location system, wherein the base station that adopts the result of position location of the mobile terminal is selected based on the respective patterns of the base stations. A control method for a position location system according to claim 5,
In the one of the base stations, the server device has a ratio of the determination result that the received electric field strength is equal to or less than the first threshold in the pattern of the base station is equal to or less than a second threshold, and If the determination result that the pattern is less than or equal to the first threshold is followed by the determination result that the pattern exceeds the first threshold, the base station is more than the base station. The base that adopts the result of positioning of the mobile terminal in preference to the other base stations that have a large proportion of the determination result that the received electric field strength of the pattern is equal to or less than the first threshold. A location control system control method characterized by selecting as a station. It is a control method of the position location system according to claim 5 or 6,
The server apparatus includes the base station configured with the determination result indicating that the received electric field strength exceeds the first threshold in all of the patterns. Positioning of the mobile terminal is prioritized over the base station in which the determination result that the threshold value exceeds 1 and the determination result that the received electric field strength is equal to or less than the first threshold are mixed. And selecting as the base station that adopts the result of the above. It is a control method of the positioning system as described in any one of Claims 5 thru | or 7, Comprising:
In the server, the determination result that the received electric field strength exceeds the first threshold and the determination result that the received electric field strength is equal to or less than the first threshold are the same rate in the pattern. When there are a plurality of the included base stations, for each reception time of the positioning signal, the determination result of the positioning signal received at the reception time indicates that the received electric field strength is the first threshold value. A control method for a position location system, comprising: selecting the base station that has transmitted the position location signal, which indicates content exceeding the base station, as the base station that employs a location result of the mobile terminal.

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