JP2013181923A - Position location method and position location system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a position location system with improved position location accuracy.SOLUTION: A base unit 20, which is provided with an antenna group 25 comprising a sufficient number of antennas 251 to form a plurality of patterns including a first antenna pair and a second antenna pair, measures a phase difference Δθ1 between position location signals 900 received by respective antennas 251 of the first antenna pair for each pattern and a phase difference Δθ2 between position location signals 900 received by respective antennas 251 of the second antenna pair for each pattern, determines a degree of multipath influence for each pattern on the basis of the phase difference Δθ1 and the phase difference Δθ2 measured for each pattern, selects a pattern least affected by multipath, and outputs a position determined from the selected pattern as a position of a moving object 3. The degree of multipath influence is determined using a difference between or sum of the phase difference Δθ1 and the phase difference Δθ2 as an indicator.

Description

  The present invention relates to a position locating method and a position locating system, and more particularly to a technique for improving position locating accuracy by a position locating system.

  Patent Document 1 is configured for the purpose of measuring the direction in which a pedestrian is heading with high accuracy and high reliability, and measuring the direction and distance from a plurality of transmission means with high accuracy and high reliability. In the three-dimensional positioning system, the quality of the received measurement signal that guides and supports the walking of pedestrians is monitored, and the measurement results are selected according to the quality of the measurement signal. It describes reducing the impact.

  In Patent Document 2, a measurement signal is radiated while periodically switching the antenna in a single transmission means, the measurement signal is received by the reception means, and the distance from the transmission means is measured by measuring the phase of the received measurement signal. In the positioning system that calculates the direction, the quality of the measurement signal transmitted and received via the redundant propagation path is monitored, the measurement result is selected according to the quality, and the propagation path of the redundant radio signal It is described that the best quality line is selected from the above to suppress the degradation of positioning accuracy due to multipath.

  In Patent Document 3, in an antenna transmission / reception system in a mobile communication system, a base station antenna is divided into a plurality of array groups according to a cell propagation environment, and each array group performs loose directional beam control. It is described that system characteristics are improved by performing parallel transmission of different data.

  In Non-Patent Document 1, a wireless signal is transmitted from a plurality of antennas installed in a base station to a portable terminal carried by a pedestrian, and the relative relationship between the portable terminal and the antenna is determined by the phase difference of the wireless signal transmitted from each antenna. A position locating system is disclosed in which a position is obtained and the current position of a pedestrian is obtained from the obtained relative position (direction, distance) and the absolute position of the base station.

JP 2010-101711 A JP 2010-101710 A JP 2003-338781 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

  As disclosed in Patent Document 1 and the like, in a positioning system that is realized using a radio signal, if the position is determined by a radio signal that is greatly influenced by multipath or reflected waves, the position location accuracy is high. It drops significantly. In particular, when the positioning system is installed indoors where there are many obstacles, the positioning signal is reflected by walls, floors, etc., and the influence of multipath and reflected waves becomes large.

  This invention is made | formed in view of such a subject, and it aims at providing the position location method and the position location system which can improve the location accuracy of the position of a moving body.

  One aspect of the present invention for achieving the above object is a method for locating the position of a mobile object, which is a radio signal for locating the position of the mobile terminal from a mobile terminal provided in the mobile object. Transmitting a position location signal to the base station, the first antenna pair and the second antenna pair, the path difference of the position location signal received by each antenna of the first antenna pair and the second The base station is provided so that a path difference of the positioning signal received by each antenna of the antenna pair matches, and the base station receives by each antenna of the first antenna pair or each antenna of the second antenna pair. A direction in which the mobile terminal exists is obtained based on the phase difference Δθ of the position location signal, the position of the mobile body is obtained based on the obtained direction, and the base station receives each antenna of the first antenna pair. By Measuring the phase difference Δθ1 of the positioning signal received by the second antenna pair, measuring the phase difference Δθ2 of the positioning signal received by each antenna of the second antenna pair, and A plurality of antennas that can form a plurality of patterns of an antenna group including a pair of antennas and the second antenna pair are provided. Based on the phase difference Δθ1 and the phase difference Δθ2 measured for each of the patterns, The degree of influence of each multipath is obtained, the pattern having the least degree of influence of the multipath is selected, and the position obtained by the selected pattern is output as the position of the moving body.

  According to the present invention, the base station measures the phase difference Δθ1 and the phase difference Δθ2 for each of two or more patterns of the antenna group, and each of the patterns based on the phase difference Δθ1 and the phase difference Δθ2 measured for each of the patterns. Multipath effect level is calculated, the pattern with the least multipath effect level is selected, and the position determined by the selected pattern is output as the position of the moving object. The position of the body can be determined. For this reason, the positioning accuracy of the position of the moving object can be improved.

  Another aspect of the present invention is the above-described position locating method, wherein the base station indicates the position of the mobile terminal, and the sign of the measurement result of the phase difference Δθ2 is inverted with respect to the measurement result of the phase difference Δθ1. The phase difference Δθ1 and the phase difference Δθ2 are measured using a measurement standard to cancel the error included in each of the measured phase difference Δθ1 and the phase difference Δθ2. The difference between the measurement result of the phase difference Δθ1 and the measurement result of the phase difference Δθ1 matches the degree of influence of the multipath of the positioning signal received from the mobile terminal by obtaining the difference with the phase difference Δθ2. The phase difference Δθ1 and the phase difference Δθ2 are measured using a measurement standard, and the difference between the phase difference Δθ1 and the phase difference Δθ2 measured by the measurement is obtained.

  In addition, the base station determines the multipath influence degree that is the closest to 0 between the measured phase difference Δθ1 and the measured phase difference Δθ2 among the patterns for which the multipath influence degree is obtained. Select as few said patterns.

  As described above, the degree of influence of the multipath of the position location signal received from the mobile terminal is determined using, for example, the phase difference Δθ1 and the phase difference by using a measurement standard in which the measurement result of the phase difference Δθ2 and the sign of the measurement result of the phase difference Δθ1 match. Δθ2 is measured and can be obtained as a difference between the measured phase difference Δθ1 and the phase difference Δθ2. In addition, by selecting the pattern having the smallest difference in multipath influence as the pattern having the smallest difference in multipath, it is possible to reliably select the pattern having the least multipath influence.

  Another aspect of the present invention is the above-described position locating method, wherein the base station indicates the position of the mobile terminal, and the sign of the measurement result of the phase difference Δθ2 is inverted with respect to the measurement result of the phase difference Δθ1. The phase difference Δθ1 and the phase difference Δθ2 are measured using a measurement standard to cancel the error included in each of the measured phase difference Δθ1 and the phase difference Δθ2. It is obtained by taking the difference with the phase difference Δθ2, and the degree of influence of the multipath of the positioning signal received from the mobile terminal is obtained as the sum of the measured phase difference Δθ1 and the phase difference Δθ2.

  In addition, the base station determines the sum of the measured phase difference Δθ1 and the measured phase difference Δθ2 among the patterns for which the degree of multipath influence is obtained, respectively, of the measured phase difference Δθ1 and the phase difference Δθ2. Is selected as the pattern having the least influence of the multipath.

  As described above, the degree of influence of the multipath of the position location signal received from the mobile terminal is determined by using, for example, the phase difference Δθ1 and the phase difference Δθ1 using a measurement standard in which the sign of the measurement result of the phase difference Δθ2 is inverted with respect to the measurement result of the phase difference Δθ1 The phase difference Δθ2 is measured and can be obtained as the sum of the phase difference Δθ1 and the phase difference Δθ2 measured thereby. Further, by selecting the sum that is closest to the sum of errors included in each of the measured phase difference Δθ1 and phase difference Δθ2 as the pattern having the least multipath influence, the multipath influence can be reduced. The least number of patterns can be selected with certainty.

  Another aspect of the present invention is the above-described position locating method, wherein the first antenna pair and the second antenna pair are equally spaced from each other of the first antenna pair and each of the second antenna pair. And is arranged in a square shape on a plane.

  By arranging the antennas of the first antenna pair and the antennas of the second antenna pair in such a manner, the path difference of the positioning signal received by each antenna of the first antenna pair and the second antenna It is possible to reliably match the path difference of the position location signals received by each antenna of the pair.

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

  ADVANTAGE OF THE INVENTION According to this invention, the positioning accuracy of the position by a positioning system can be improved.

It is a figure showing a schematic structure of position location system 1 of a 1st embodiment. 2 is a diagram illustrating a hardware configuration of a server device 10. FIG. 3 is a diagram illustrating functions of a server device 10. FIG. It is a figure explaining the hardware constitutions of the mobile terminal. 2 is a diagram illustrating main functions of a mobile terminal 30. FIG. 2 is a diagram illustrating a hardware configuration of a base station 20. FIG. 2 is a diagram illustrating main functions of a base station 20. FIG. 5 is a diagram illustrating details of a multipath evaluation information acquisition unit 205. FIG. It is a figure which shows an example of the data format of the location signal 900. FIG. It is a figure which shows an example of the mode around the installation site of the base station. FIG. 3 is a diagram for explaining the positional relationship between each antenna 251 constituting a group of antennas 25 and a mobile terminal 30. It is a figure explaining the positional relationship of the base station 20 and the mobile terminal 30. FIG. 6 is a diagram illustrating a method for realizing a pattern of an antenna group 25 by a plurality of antennas 251 provided in a base station 20. FIG. It is a flowchart explaining position location process S1400. It is a flowchart explaining position location processing S1500.

  FIG. 1 shows a schematic configuration of a position location system 1 described as an embodiment. The position locating system 1 is, for example, a system that monitors the current position of a moving body 3 (vehicles, pedestrians, etc.), a system related to ensuring the safety of the moving body 3, guidance to the moving body 3 and guidance to the destination. System to perform, system for providing information around the current location to the moving body 3, evacuation guidance system for the moving body 3 (person) in the underground or building streets, moving body 3 in the warehouse, factory, etc. (goods, transport vehicles, etc.) ) And a guidance system for a moving body 3 (robot, transport vehicle, etc.) in a factory or the like.

  The position location system 1 is mounted or carried on a server device 10 provided in a data center, a system center, or the like, a plurality of base stations 20 provided in various locations in an area to which the position location system 1 is applied, and a mobile unit 3. The mobile terminal 30 is configured to be included.

  The base station 20 is provided at a predetermined height position of the structure 2 (such as a pillar or a building wall if indoors, or a utility pole or steel tower if outdoor). The base station 20 and the mobile terminal 30 are communicably connected to the server device 10 via a wired or wireless (communication using electromagnetic waves, etc.) communication network 5 (private line, public line, Internet, etc.).

  FIG. 2 shows a hardware configuration of the server device 10. As shown in the figure, the server device 10 includes a central processing unit 11 configured by using a CPU, an MPU, and the like, a storage device 12 configured by a semiconductor memory (RAM, ROM, NVRAM, etc.) and a hard disk device, and a keyboard. And an input device 13 such as a mouse, a display device 14 such as a liquid crystal display, and a communication interface 15 for connecting the server device 10 to the communication network 5. These components are connected to each other via a bus 18 so as to communicate with each other. On the display device 14, for example, information indicating the current position and moving direction of the moving body 3 (mobile terminal 30) is displayed in real time.

  FIG. 3 shows main functions of the server device 10. As illustrated in FIG. 1, the server device 10 includes an information collection unit 101, an information provision unit 102, and a setting information storage unit 103. These functions are realized by hardware included in the server device 10 or by the central processing unit 11 of the server device 10 reading and executing a program stored in the storage device 12.

  The information collection unit 101 collects information such as the current position of the mobile terminal 30 from the base station 20 or the mobile terminal 30 as needed. For example, the information providing unit 102 provides the mobile terminal 30 and the base station 20 with route guidance information, guidance information to the destination, geographical information around the current position, monitoring information such as the current position and moving direction of the moving body 3. Various types of information such as information related to ensuring the safety of the mobile unit 3 are provided. The setting information storage unit 103 stores, for example, information (latitude, longitude, installation height, etc.) indicating the installation position of the base station 20 as setting information.

  FIG. 4 shows the hardware configuration of the mobile terminal 30. As shown in the figure, a mobile terminal 30 includes a central processing unit 31 configured using a CPU, an MPU, and the like, a storage device 32 configured with a semiconductor memory (RAM, ROM, NVRAM, etc.), a hard disk device, and the like. A wireless communication interface 33 for transmitting a position location signal to be transmitted and performing wireless communication with another device, an antenna 34 used for wireless communication performed by the wireless communication interface 33, an input device 35 such as a touch panel and operation buttons, and the like. A display device 36 such as a liquid crystal display or an organic EL display is provided. These components are communicably connected to each other via a bus 39.

  The antenna 34 is, for example, a directional antenna. 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. Note that when the mobile terminal 30 is used indoors where obstacles such as walls exist, 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. It is because it can attenuate.

  FIG. 5 shows main functions of 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 above functions, the position location signal transmission unit 301 transmits a radio signal (hereinafter referred to as a position location signal) used for location of the mobile terminal 30 from the radio communication interface 33. The position location signal transmitting unit 301 has a function of automatically transmitting a position location signal when a preset timing (for example, every predetermined time, time registered by the user, etc.) arrives. For example, the position location signal transmission unit 301 automatically transmits a position location signal repeatedly or continuously at a sufficiently short time interval.

  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 the person who is the moving body 3 to the display device 36.

  FIG. 6 shows the hardware configuration of the base station 20. The base station 20 includes a central processing unit 21 configured using a CPU, an MPU, and the like, a storage device 22 including a semiconductor memory (RAM, ROM, NVRAM, etc.) and a hard disk device, and the base station 20 as a communication network 5. A communication interface 23 for connection, a wireless communication interface 24 for performing wireless communication, an antenna group 25, an antenna changeover switch 26, and the like are provided. Each component is communicably connected via the bus 28.

  The central processing unit 21 implements various functions provided in 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 transmitted from the mobile terminal 30.

  The antenna group 25 includes at least four antennas 251 (directional antennas, circularly polarized directional antennas, etc.). The antenna changeover switch 26 selects one of the antennas 251 constituting the antenna group 25 and connects the selected antenna 251 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 251. 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. 7 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, a position location unit 204, a multipath evaluation information acquisition unit 205, an out-of-service determination unit 206, and a pattern selection. A unit 206 and a position location result output unit 208. Note that these functions are realized by hardware provided 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 transmits or receives data to / from the mobile terminal 30 or the server device 10 through the wireless communication interface 24 or the communication interface 23.

  The location signal receiving unit 202 receives the location signal transmitted from the mobile terminal 30 by controlling the radio communication interface 24 and the antenna changeover switch 26.

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

  The position locating unit 204 determines the position of the moving body 3 for each pattern while switching a pattern to be described later of the antenna group 25 based on the position locating signal received by the position locating signal receiving unit 202. Information (location result) indicating the position of the moving body determined by the position determination unit 204 is stored by the multipath evaluation information acquisition unit 205 in association with the pattern identifier (hereinafter referred to as pattern ID).

  The multipath evaluation information acquisition unit 205 acquires information (hereinafter referred to as evaluation information) that is the basis for determining the degree of influence of multipath and reflected waves on the position location signal 900 transmitted from the mobile terminal 30. To do.

  FIG. 8 shows details of the multipath evaluation information acquisition unit 205. As shown in the figure, the multipath evaluation information acquisition unit 205 includes a first phase difference measurement unit 2051, a second phase difference measurement unit 2052, and an evaluation information generation storage unit 2053.

  The first phase difference measuring unit 2051 includes a first antenna 251 and a second antenna 251 (hereinafter, a set of the first antenna 251 and the second antenna 251 is referred to as a first antenna pair) among the four antennas 251 of the base station 20. )), The position determination signal transmitted from the mobile terminal 30 is received, and the phase difference Δθ1 of the position determination signal received by each of the first antenna 251 and the second antenna 251 is measured.

  The second phase difference measuring unit 2052 includes a third antenna 251 and a fourth antenna 251 (hereinafter, a set of the third antenna 251 and the fourth antenna 251 is referred to as a second antenna pair) among the four antennas 251 of the base station 20. )), The position determination signal transmitted from the mobile terminal 30 is received, and the phase difference Δθ2 of the position determination signal received by each of the third antenna 251 and the fourth antenna 251 is measured.

  Note that the first antenna pair and the second antenna pair are different from each other in the path difference between the position determination signals received by the respective antennas 251 of the first antenna pair and the position determination received by the respective antennas 251 of the second antenna pair. Positioned so that the signal path difference matches.

  The evaluation information generation storage unit 2053 generates the above-described evaluation information based on the phase difference Δθ1 acquired by the first phase difference measurement unit 2051 and the phase difference Δθ2 acquired by the second phase difference measurement unit 2052. The generated evaluation information is stored in association with the position determination result of the position of the mobile 3 determined by the position determination unit 204 using the pattern ID and the position determination signal 900 described above.

  Returning to FIG. 7, the out-of-service determination unit 206 determines whether or not the base station 20 needs to perform handover based on the evaluation information for each pattern stored in the evaluation information generation storage unit 2053.

  The pattern selection unit 207 compares the evaluation information for each pattern stored by the multipath evaluation information acquisition unit 205, and selects the pattern that has received the position location signal with the least degree of multipath influence.

  The position determination result output unit 208 outputs the position determined by the position determination unit 204 according to the pattern selected by the position determination signal selection unit 207 as the position of the moving body 3. The position of the moving body 3 output by the position location result output unit 208 is transmitted to the server device 10 and the mobile terminal 30 by the communication processing unit 201 as needed.

= Positioning principle =
Next, the principle of position location by the location system 1 will be described.

  The location signal transmission unit 301 of the mobile terminal 30 transmits a location signal from the antenna 34 provided in itself. On the other hand, the radio communication interface 23 of the base station 20 receives a position location signal composed of a radio signal subjected to spectrum spreading while periodically switching a plurality of antennas 251 constituting the antenna group 25.

  FIG. 9 shows an example of the data format of the position location signal transmitted from the mobile terminal 30. As shown in the figure, the position location signal 900 includes signals and information such as a control signal 911, a measurement signal 912, and terminal information 913.

  Among these, the control signal 911 includes a modulated wave and various control signals. The measurement signal 912 includes a non-modulated wave of about several milliseconds (for example, a signal used for detecting the direction in which the mobile terminal 30 exists 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 913 includes information for identifying the mobile terminal 30 (hereinafter referred to as mobile terminal ID).

  FIG. 10 illustrates the positional relationship between the base station 20 and the mobile terminal 30. As shown in the figure, the mobile terminal 30 is at a ground height h (m), and the base station 20 is fixed at a ground height H (m). The straight line distance from directly below the base station 20 to the mobile terminal 30 is L (m).

  FIG. 11 shows the relationship between the plurality of antennas 251 constituting the antenna group 25 of the base station 20 and the mobile terminal 30. As shown in the figure, the antenna group 25 has an interval equal to or less than one wavelength of the positioning signal 900 (for example, a wavelength λ = 12.5 cm when a 2.4 GHz band radio wave is used as the positioning signal 900). And four circularly polarized directional antennas (hereinafter referred to as antennas 251a to 251d) arranged adjacently at regular intervals in a substantially square shape in plan view. Note that each of the antennas 251a to 251d is installed, for example, with the directivity direction obliquely downward.

  In the present embodiment, the first antenna 251 described above is assumed to be the antenna 251a, the second antenna 251 is assumed to be the antenna 251b, the third antenna 251 is assumed to be the antenna 251c, and the fourth antenna 251 is assumed to be It is assumed that the antenna 251d.

In the figure, if the angle formed by the horizontal direction at the height of the antenna group 25 and the direction of the mobile terminal 30 with respect to the antenna group 25 is α,
α = arcTan (D (m) / L (m)) = arcSin (ΔL (cm) / 3 (cm))
There is a relationship. Note that ΔL (cm) is a difference in propagation path length between the two specific antennas 251 and the mobile terminal 30 among the antennas 251 constituting the antenna group 25 (hereinafter also referred to as a path difference). ).

Here, when the phase difference between the positioning signals 900 received by the two specific antennas 251 constituting the antenna group 25 is Δθ,
ΔL (cm) = Δθ / (2π / λ (cm))
There is a relationship. For example, when a 2.4 GHz band radio wave is used as the position location signal 900, λ = 12.5 (cm).
α = arcSin (Δθ / π)
There is a relationship. Also, within the measurable range (−π / 2 <Δθ <π / 2), α = Δθ (radian), so the direction in which the base station 20 exists can be specified from the above equation.

FIG. 12 shows the positional relationship between the base station 20 and the mobile terminal 30 at the installation site of the base station 20. As shown in the figure, an orthogonal coordinate axis with the ground height of the antenna group 25 of the base station 20 as H (m), the ground height of the mobile terminal 30 as h (m), and the position of the ground surface directly below the base station 20 as the origin. When (X axis, Y axis) is set, the angle formed by the direction from the base station 20 to the mobile terminal 30 and the X axis is ΔΦ (x), and the direction from the base station 20 to the mobile terminal 30 is formed by the Y axis. If the angle is ΔΦ (y), the position of the mobile terminal 30 with respect to the origin can be obtained from the following equation.
Δd (x) = (H−h) × Tan (ΔΦ (x))
Δd (y) = (H−h) × Tan (ΔΦ (y))
If the position of the origin is (X1, Y1), the position (Xx, Yy) of the mobile terminal 30 can be obtained from the following equation.
Xx = X1 + Δd (x)
Yy = Y1 + Δd (y)

  The position locating method described above is also described in detail in, for example, Japanese Patent Application Laid-Open Nos. 2004-184078, 2005-351877, 2005-351878, and 2006-23261. Has been.

  By the way, in the position determination performed as described above, an error caused by a frequency deviation generated in the crystal oscillators of the base station 20 and the mobile terminal 30 becomes a problem. For example, when the frequency stability of the crystal oscillator is ± 0.5 ppm, a maximum frequency deviation (2400 Hz) of 1 ppm occurs between the base station 20 and the mobile terminal 30, and the switching period of the antenna changeover switch 26 is 32 μs. For example, a phase difference (error) of 2400 Hz × 32 μs × 360 ° = 27.65 ° is generated. Therefore, in the position locating system 1 of the present embodiment, this measurement error is canceled as follows.

First, the phase difference Δθ1 of the positioning signal 900 received by each antenna of the first antenna pair (the first antenna 251a and the second antenna 251b) (result of measuring the phase of the second antenna 251b with reference to the first antenna 251a) Is a phase difference caused by a difference (path difference) between the propagation path of the positioning signal 900 from the mobile terminal 30 to the first antenna 251a and the propagation path of the positioning signal 900 from the mobile terminal 30 to the second antenna 251b. If Δθt1 and the measurement error is F1, it can be expressed by the following equation.
Δθ1 = Δθt1 + F1 Equation 1

On the other hand, the phase difference Δθ2 of the positioning signal 900 received by each antenna (the third antenna 251c and the fourth antenna 251d) of the second antenna pair (the result of measuring the phase of the fourth antenna 251d with reference to the third antenna 251c) ) Is a phase difference caused by a difference (path difference) between the propagation path of the positioning signal 900 from the mobile terminal 30 to the third antenna 251c and the propagation path of the positioning signal 900 from the mobile terminal 30 to the fourth antenna 251d. Is Δθt2 and the measurement error is F2, it can be expressed by the following equation.
Δθ2 = −Δθt2 + F2 Equation 2

Next, if the difference between both sides of Formula 1 and Formula 2 is taken, it becomes as follows.
Δθ1−Δθ2 = (Δθt1 − (− Δθt2)) + (F1−F2) Equation 3

As described above, the first antenna pair and the second antenna pair include the path difference of the positioning signal 900 received by the antennas 251a and 251b of the first antenna pair and the second antenna pair. It is provided so that the path difference of the positioning signal 900 received by the antennas 251c and 251d matches. Therefore, if this value is θt, the value of (Δθt1 − (− Δθt2)) on the right side is 2θt. Since the errors F1 and F2 are usually substantially the same when measuring the first antenna pair and when measuring the second antenna pair, the value of (F1-F2) on the right side is as close to 0 as possible. Therefore, if these values are substituted into Equation 3 and the equation is modified, it becomes as follows.
θt = (Δθ1-Δθ2) / 2 Formula 4

  Thus, by measuring the phase difference between the first antenna pair and the second antenna pair, the measurement errors F1 and F2 can be canceled out, and the phase difference θt due to the path difference is obtained with high accuracy. be able to. For this reason, the accuracy of position determination can be improved.

  If the frequency deviation is reduced by providing an AGC (Automatic Gain Controller) or the like on the phase measurement side, the value of (F1-F2) on the right side of Equation 3 can be made closer to 0, and the position The accuracy of orientation can be further increased.

= Principle of whether or not it is a direct wave
In order to ensure the positioning accuracy of the position of the moving body 3 in the positioning system 1, it is necessary to perform positioning based on the positioning signal 900 received as a direct wave from the mobile terminal 30 by the base station 20. Below, the principle (determination principle (the 1) and determination principle (the 2)) which determines whether the position location signal 900 sent from the mobile terminal 30 is a direct wave is demonstrated.

<Determination principle (part 1)>
In the determination principle (part 1), the base station 20 measures the phase difference Δθ1 of the positioning signal 900 received by each antenna 251 of the first antenna pair (the phase of the second antenna 251b with reference to the first antenna 251a). And the phase difference Δθ2 of the positioning signal 900 received by each antenna 251 of the second antenna pair was measured (the phase of the third antenna 251c was measured using the fourth antenna 251d as a reference) and measured. Based on the phase difference Δθ1 and the phase difference Δθ2, it is determined whether or not the position location signal 900 sent from the mobile terminal 30 is a direct wave.

Here, the phase difference Δθ1 of the positioning signal 900 received by each antenna (first antenna 251a and second antenna 251b) of the first antenna pair (the result of measuring the phase of the second antenna 251b with reference to the first antenna 251a) ) Is a phase difference caused by a difference (path difference) between the propagation path of the positioning signal 900 from the mobile terminal 30 to the first antenna 251a and the propagation path of the positioning signal 900 from the mobile terminal 30 to the second antenna 251b. Is Δθt1, the measurement error is F1, and the influence of multipath or reflected wave is M1, the following equation can be expressed.
Δθ1 = Δθt1 + F1 + M1 Equation 5

Further, the phase difference Δθ2 of the positioning signal 900 received by each antenna (the third antenna 251c and the fourth antenna 251d) of the second antenna pair (result of measuring the phase of the third antenna 251c with the fourth antenna 251d as a reference) Is a phase difference caused by a difference (path difference) between the propagation path of the positioning signal 900 from the mobile terminal 30 to the third antenna 251c and the propagation path of the positioning signal 900 from the mobile terminal 30 to the fourth antenna 251d. Δθt2 (Because the reference is reversed at the time of phase measurement, the sign of Δθt2 is reversed in the case of the above-mentioned position determination (Equation 2)), the measurement error is F2, the influence of multipath and reflected wave If M is M2, it can be expressed by the following equation.
Δθ2 = Δθt2 + F2 + M2 Equation 6

Next, if the difference between both sides of Formula 5 and Formula 6 is taken, it becomes as follows.
Δθ1−Δθ2 = (Δθt1−Δθt2) + (F1−F2) + (M1−M2)
... Formula 7

As described above, the first antenna pair and the second antenna pair include the path difference of the positioning signal 900 received by each antenna 251 of the first antenna pair and each antenna 251 of the second antenna pair. Therefore, the value of (Δθt1−Δθt2) on the right side of Equation 7 is as close to 0 as possible. Further, as described above, the errors F1 and F2 are usually substantially the same when measuring the first antenna pair and when measuring the second antenna pair, so the value of (F1-F2) on the right side of Equation 7 is Infinitely close to 0. Therefore, if these values are substituted, Equation 7 becomes as follows.
Δθ1−Δθ2 = M1−M2 Equation 8

  Here, since each antenna of the first antenna pair and each antenna of the second antenna pair are physically different in position as shown in FIG. 11, the influence of multipath and reflected waves on each antenna 251 is not affected. Different from each other, when the positioning signal 900 is a multipath or a reflected wave, M1 ≠ M2. Conversely, if the position location signal 900 is a direct wave, M1 = M2. For this reason, the mobile terminal 30 checks whether or not the phase difference Δθ1 and the phase difference Δθ2 match (whether the difference between the two is zero or at least equal to or less than a preset reference value). It can be determined whether or not the position location signal 900 sent from is a direct wave.

  The mechanism described above (determination principle (part 1)) can be applied to the case where either ΔΦ (x) or ΔΦ (y) described above is obtained. That is, when obtaining each of ΔΦ (x) and ΔΦ (y), it is possible to individually determine the presence or absence of a multipath or a reflected wave.

  As described above, according to the determination principle (part 1), it can be determined based on the difference whether or not the position location signal 900 received from the mobile terminal 30 is a direct wave.

<Determination principle (2)>
In the determination principle (part 2), the base station 20 measures the phase difference Δθ1 of the positioning signal 900 received by each antenna 251 of the first antenna pair (the phase of the second antenna 251b with reference to the first antenna 251a). And the phase difference Δθ2 of the positioning signal 900 received by each antenna 251 of the second antenna pair was measured (the phase of the fourth antenna 251d was measured using the third antenna 251c as a reference) and measured. Based on the phase difference Δθ1 and the phase difference Δθ2, it is determined whether or not the position location signal 900 sent from the mobile terminal 30 is a direct wave.

Here, the phase difference Δθ1 of the positioning signal 900 received by each antenna (first antenna 251a and second antenna 251b) of the first antenna pair (the result of measuring the phase of the second antenna 251b with reference to the first antenna 251a) ) Is a phase difference caused by a difference (path difference) between the propagation path of the positioning signal 900 from the mobile terminal 30 to the first antenna 251a and the propagation path of the positioning signal 900 from the mobile terminal 30 to the second antenna 251b. Is Δθt1, the measurement error is F1, and the influence of multipath or reflected wave is M1, the following equation can be expressed.
Δθ1 = Δθt1 + F1 + M1 Equation 9

Further, the phase difference Δθ2 of the positioning signal 900 received by each antenna of the second antenna pair (the third antenna 251c and the fourth antenna 251d) (result of measuring the phase of the fourth antenna 251d with the third antenna 251c as a reference) Is a phase difference caused by a difference (path difference) between the propagation path of the positioning signal 900 from the mobile terminal 30 to the third antenna 251c and the propagation path of the positioning signal 900 from the mobile terminal 30 to the fourth antenna 251d. Δθt2 (Because the reference is the same when measuring the phase, the sign of Δθt2 is the same as in the case of the above-mentioned position determination (Equation 2)), the measurement error is F2, the influence of multipath and reflected wave Is M2 (because the reference is the same when measuring the phase, the sign coincides with Δθt2).
Δθ2 = −Δθt2 + F2-M2 Equation 10

Next, if the sum of both sides of Equation 9 and Equation 10 is taken, the result is as follows.
Δθ1 + Δθ2 = (Δθt1−Δθt2) + F1 + F2 + (M1−M2) Expression 11

As described above, the first antenna pair and the second antenna pair include the path difference of the positioning signal 900 received by each antenna 251 of the first antenna pair and each antenna 251 of the second antenna pair. Therefore, the value of (Δθt1−Δθt2) on the right side of Equation 11 is 0. Therefore, Formula 11 becomes as follows.
Δθ1 + Δθ2 = (F1 + F2) + (M1-M2) Expression 12

  Here, when F1 and F2 are sufficiently stable (time fluctuation is small), the value of (F1 + F2) (if F1 and F2 are equal (this value is assumed to be F) (F1 + F2) = 2F) is substantially constant. Can be considered. Therefore, if (F1 + F2) is known in advance as an empirical value or the like, whether or not the value Δθ1 + Δθ2 on the left side of Expression 12 matches (F1 + F2) (whether the difference between the two is 0 or at least preset) It is possible to determine whether or not the position location signal 900 sent from the mobile terminal 30 is a direct wave by checking whether or not it is equal to or less than a reference value (in the case of a direct wave, M1 = 0, Since M2 = 0, (M1-M2) = 0, and when not a direct wave, M1 ≠ 0 and M2 ≠ 0 (M1-M2) ≠ 0).

  Note that the mechanism described above (determination principle (part 2)) can be applied to the determination of either ΔΦ (x) or ΔΦ (y) described above. That is, when obtaining each of ΔΦ (x) and ΔΦ (y), it is possible to individually determine the presence or absence of a multipath or a reflected wave.

  As described above, according to the determination principle (part 2), the error included in each of the phase difference Δθ1 and the phase difference Δθ2 is sufficiently stable compared to the component due to the influence of the indirect wave, As long as the error value (F1 + F2) is given as an empirical value, it can be determined based on the above sum whether or not the location signal 900 received from the mobile terminal 30 is a direct wave.

  In the determination principle (part 2), it is determined whether or not the position location signal 900 received from the mobile terminal 30 is a direct wave. The phase difference Δθ1 and the phase difference Δθ2 measured in order to obtain the position of the mobile terminal 30 are used. (Δθ2 measured using a measurement standard whose sign is inverted with respect to the measurement result of the phase difference Δθ1) can be used as it is, so that the position determination of the mobile terminal 30 and the position determination signal 900 are direct waves. The determination of whether or not can be done by a single measurement, and the processing load on the base station 20 and the mobile terminal 30 related to the position determination and the determination of whether or not it is a direct wave can be reduced.

= Improvement of orientation accuracy =
In the above-described determination principle (part 1), it is determined whether or not the position location signal 900 is a direct wave by examining the difference between the phase difference Δθ1 and the phase difference Δθ2 (Equation 8). The difference value obtained at this time indicates the degree of multipath influence of the position determination signal 900. The position determination signal 900 in which the difference between the phase difference Δθ1 and the phase difference Δθ2 is a value close to 0 indicates the influence of multipath. The degree is small.

  In the above-described determination principle (part 2), it is determined whether or not the position location signal 900 is a direct wave by examining the sum of the phase difference Δθ1 and the phase difference Δθ2 (Equation 12). The value of the sum obtained upon determination indicates the degree of multipath influence of the position determination signal 900. The position determination signal 900 in which the sum of the phase difference Δθ1 and the phase difference Δθ2 is close to F1 + F2 This indicates that the degree of influence is small.

  Thus, in the case of the determination principle (part 1), the difference between the phase difference Δθ1 and the phase difference Δθ2, and in the case of the determination principle (part 2), the sum of the phase difference Δθ1 and the phase difference Δθ2 is used as an index. As a result, it is possible to determine the degree of multipath influence of the position location signal 900 received by the antenna group 25.

  By the way, according to the principle of space diversity, if the physical position of the mobile terminal 30 differs by about 1/4 wavelength to 1 wavelength in an indirect wave composed of a composite wave of a plurality of reflected waves and a direct wave, the position location signal 900 The degree of multipath influence on the image changes.

  Therefore, the base station 20 is provided with a number of antennas 251 that can configure the antenna group 25 having a plurality of patterns by selecting the antennas that constitute the first antenna pair and the second antenna pair. If 900 is received, it is possible to acquire the position location signal 900 having a different degree of multipath influence.

  Then, for example, based on the phase difference Δθ1 and phase difference Δθ2 measured for each of two or more patterns, the degree of influence of each multipath of the above pattern is obtained, and the pattern having the least degree of influence of the multipath is selected and selected. If the position determined by the pattern is output as the position of the moving body 3, the positioning accuracy of the position of the moving body 3 can be improved.

  FIG. 13 shows an example of a method for realizing the pattern of the antenna group 25. As shown in the figure, in this example, nine antennas 25 are formed in the base station 20 so as to configure the antenna group 25 including the first antenna pair and the second antenna pair over four patterns A, B, C, and D. 251 is provided on the antenna base 131. In the figure, the interval between adjacent antennas 251 is ¼ wavelength to 1 wavelength of the position location signal 900.

  The figure shows only an example of a method for realizing the pattern of the antenna group 25, and the pattern can be realized by other methods. However, the pattern of the antenna group 25 needs to be provided so that the degree of multipath influence of each pattern can be compared when the position determination is performed based on the same position determination signal 900.

  In the figure, the antenna group 25A of pattern A is composed of four antennas 251Aa, 251Ab, 251Ac, and 251Ad in the lower left of the antenna base 131. In the pattern A, the antenna 251Aa and the antenna 251Ab constitute a first antenna pair, and the antenna 251Ac and the antenna 251Ad constitute a second antenna pair.

  The antenna group 25B of the pattern B includes four antennas 251Ba, 251Bb, 251Bc, and 251Bd on the lower right side of the antenna base 131. In the pattern B, the antenna 251Ba and the antenna 251Bb constitute a first antenna pair, and the antenna 251Bc and the antenna 251Bd constitute a second antenna pair.

  The antenna group 25C of the pattern C includes four antennas 251Ca, 251Cb, 251Cc, and 251Cd on the upper right side of the antenna base 131. In the pattern C, the antenna 251Ca and the antenna 251Cb constitute a first antenna pair, and the antenna 251Cc and the antenna 251Cd constitute a second antenna pair.

  The antenna group 25D of the pattern D includes four antennas 251Da, 251Db, 251Dc, and 251Dd at the upper left of the antenna base 131. In the pattern D, the antenna 251Da and the antenna 251Db constitute a first antenna pair, and the antenna 251Dc and the antenna 251Dd constitute a second antenna pair.

  In addition, by configuring the antenna group 25 having a plurality of patterns on the base station 20 side to acquire the position location signal 900 having a different degree of multipath influence, no special configuration is provided on the mobile terminal 30 side. In addition, it is possible to acquire the position location signal 900 having a different degree of multipath influence on the base station 20 side. For this reason, it is possible to improve the positioning accuracy without providing a special configuration on the mobile terminal 30 side (for example, without increasing the number of antennas 34, etc.), simplifying the mobile terminal 30, and reducing the manufacturing cost. Can be achieved.

= Positioning process =
Next, processing performed by the position location system 1 when the position of the moving body 3 is determined while determining the multipath influence degree of the position location signal 900 based on the above-described index will be described.

  FIG. 14 is a flowchart illustrating an example of processing performed by the position location system 1 (hereinafter referred to as location location processing S1400). Hereinafter, the location determination process S1400 will be described with reference to FIG.

  As shown in the figure, the mobile terminal 30 provided in the moving body 3 has received the transmission timing of the position location signal 900 (for example, continuously, at regular intervals (periodically), preset time, etc.). Then (S1411: YES), the position location signal 900 is transmitted continuously or at a sufficiently short time interval (S1412).

  When the base station 20 receives the positioning signal 900 (S1421), the base station 20 selects a pattern of the antenna group 25 (S1422), and determines the position of the moving body 3 based on the positioning signal 900 received by the antenna group 25 of the selected pattern. Perform (S1423).

  Next, the base station 20 evaluates the position determination signal 900 received by the antenna group 25 of the selected pattern (in the case of the determination principle (part 1), the difference between the phase difference Δθ1 and the phase difference Δθ2, the determination principle (part 2)). In the case of (1), a sum of the phase difference Δθ1 and the phase difference Δθ2) is generated (S1424), and the generated evaluation information is stored with the result of the position determination performed in S1423 and the pattern ID of the selected pattern (see FIG. S1424).

  Subsequently, the base station 20 determines whether all patterns have been selected in S1422 (S1426). If all patterns have been selected (S1426: YES), the process proceeds to S1427, and if an unselected pattern remains (S1426: NO), the process returns to S1422. In the present embodiment, it is assumed that the base station 20 stores patterns of all antenna groups 25 to be selected in advance.

  In S1427, the base station 20 selects the pattern with the least multipath influence of the received positioning signal 900 based on the evaluation information of each pattern stored in S1425 by the method described above.

  When the determination of the degree of multipath influence is performed based on the determination principle (part 1), the base station 20 receives the multipath of the position location signal 900 that has received the pattern in which the difference between the phase difference Δθ1 and the phase difference Δθ2 is closest to zero. Select the pattern with the least effect.

  When the determination of the degree of multipath influence is performed based on the determination principle (part 2), the base station 20 receives the pattern of the multipath of the positioning signal 900 that has received a pattern in which the sum of the phase difference Δθ1 and the phase difference Δθ2 is closest to F1 + F2. Select the pattern with the least influence.

  Next, the base station 20 outputs the result of position location according to the selected pattern as the position location result of the mobile unit 3 (S1428).

  Thus, according to the above method, the base station 20 measures the phase difference Δθ1 and the phase difference Δθ2 for each of the two or more patterns of the antenna group 25, and the phase difference Δθ1 and the phase difference measured for each of the patterns. Since the degree of influence of each multipath of the pattern is obtained based on Δθ2, the pattern having the smallest degree of influence of the multipath is selected, and the position obtained by the selected pattern is output as the position of the moving body 3. Positioning accuracy can be improved.

= Out-of-service judgment function =
The range in which the position can be determined by the base station 20 (hereinafter referred to as an area that can be determined) is a range in which direct waves can reach the mobile terminal 30 from the base station 20, and is provided in the base station 20, for example. It depends on the directivity angle of the antenna 251. For example, when the antenna 251 having a directivity angle of 90 ° is used, the positionable area is a circle whose radius is the difference (H−h) between the height H of the base station 20 and the height h of the mobile terminal 30. It becomes an area.

  Here, when the mobile terminal 30 exists outside the area that can be located, the degree of multipath influence of the position location signal 900 received for any of the above-described patterns increases. Therefore, whether or not the mobile terminal 30 is outside the area that can be located is determined by checking whether or not the multipath influence degree of the position location signal 900 received in each pattern exceeds a preset threshold value. Can be determined.

  In addition, when the mobile terminal 30 exists outside the area where the position can be determined, the variation in the position determination result by each pattern increases. For this reason, it is possible to determine whether or not the mobile terminal 30 exists outside the area that can be determined by checking whether or not the degree of variation in the orientation results by each pattern deviates from a preset range. . Note that the degree of variation in the orientation results of each pattern can be grasped as, for example, the difference between the maximum value and the minimum value of the orientation results of each pattern, the variance of orientation results of each pattern, and the like.

  The determination as to whether or not the mobile terminal 30 exists outside the area that can be determined is made, for example, when the mobile terminal 30 moves in a wide area where a plurality of base stations 20 are continuously arranged. It is useful in controlling handover performed between the stations 20, and by determining whether or not the mobile terminal 30 exists outside the area that can be determined by these methods, handover performed between the adjacent base stations 20 is performed. Can be done appropriately.

  FIG. 15 is an example of processing performed by the location system 1 (hereinafter referred to as location processing S1500) when handover is performed by the above method. Hereinafter, the location determination processing S1500 will be described with reference to FIG.

  Of the processing steps shown in the figure, S1511 to S1526 are the same as S1411 to S1426 of FIG.

  In S1527, the base station 20 determines whether or not the mobile terminal 30 exists outside the area that can be determined based on the evaluation information stored in S1525 after performing position determination for all patterns. That is, the base station 20 examines whether the multipath influence degree of the position location signal 900 received by each pattern exceeds a preset threshold value (allowable value), or the position according to each pattern. It is determined whether or not the mobile terminal 30 is outside the area that can be determined by examining whether or not the degree of variation in orientation results deviates from a preset range (allowable range).

  When it is determined that the mobile terminal 30 exists in the area that can be determined (S1527: NO), the base station 20 selects a pattern with the least multipath effect (S1528), and moves the position determination result based on the selected pattern. The position is output as the position of the body 3 (S1529).

  On the other hand, when it is determined that the mobile terminal 30 is outside the area that can be determined (S1527: YES), the base station 20 performs handover in cooperation with another adjacent base station 20 (S1530).

  By the way, although embodiment 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, in the above embodiment, the positioning signal 900 is transmitted from the antenna 34 of the mobile terminal 30 and received by the antenna group 25 of the base station 20, and the positioning signal 900 is a direct wave at the base station 20. The position determination signal 900 is transmitted from the base station 20, the mobile terminal 30 receives the position determination signal 900, and the mobile terminal 30 receives the position determination signal 900. Alternatively, a pattern with the least multipath effect of the received position location signal 900 may be selected, and the mobile terminal 30 may perform position location based on the selected position location signal 900. In this case, if information indicating the position determined by the mobile terminal 30 is transmitted to the server device 10 or the base station 20 by the communication network 5 or wireless communication, the server device 10 or the base station 20 can also transmit the mobile 3. The position can be grasped.

  For example, the mobile terminal 30 may function as an active or passive RFID tag. In this case, the position location signal 900 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.

1 Positioning System 3 Mobile 20 Base Station 204 Positioning Unit 205 Multipath Evaluation Information Acquisition Unit 2051 First Phase Difference Measurement Unit 2052 Second Phase Difference Measurement Unit 2053 Evaluation Information Generation Storage Unit 206 Out-of-Range Determination Unit 207 Pattern Selection Unit 208 Positioning result output unit 25 Antenna group 251 Antenna 251a First antenna 251b Second antenna 251c Third antenna 251d Fourth antenna 30 Mobile terminal 301 Positioning signal transmitter 900 Positioning signal 34 Antenna S1400 Positioning processing S1500 Positioning processing

Claims (12)

A method for locating a moving object,
From a mobile terminal provided in the mobile body, a location signal that is a radio signal for locating the location of the mobile terminal is transmitted,
The base station receives the first antenna pair and the second antenna pair by the path difference of the positioning signal received by each antenna of the first antenna pair and each antenna of the second antenna pair. Provided to match the path difference of the position location signal,
The base station determines a direction in which the mobile terminal exists based on a phase difference Δθ of the positioning signals received by each antenna of the first antenna pair or each antenna of the second antenna pair. Obtaining the position of the moving body based on the direction;
The base station
Measuring the phase difference Δθ1 of the positioning signals received by each antenna of the first antenna pair;
Measuring the phase difference Δθ2 of the positioning signals received by each antenna of the second antenna pair;
The base station is provided with a number of antennas that can form a plurality of patterns of antenna groups including the first antenna pair and the second antenna pair,
Based on the phase difference Δθ1 and the phase difference Δθ2 measured for each of the patterns, the degree of influence of each multipath of the pattern is obtained,
Select the pattern with the least influence of the multipath,
A position locating method, wherein the position obtained by the selected pattern is output as the position of the moving body. The position locating method according to claim 1,
The base station
The position of the mobile terminal is measured by measuring the phase difference Δθ1 and the phase difference Δθ2 using a measurement standard in which the measurement result of the phase difference Δθ2 is reversed in sign with respect to the measurement result of the phase difference Δθ1. In order to cancel out the errors included in each of the phase difference Δθ1 and the phase difference Δθ2, it is obtained by taking the difference between the phase difference Δθ1 and the phase difference Δθ2.
The degree of influence of the multipath of the positioning signal received from the mobile terminal is measured using the measurement reference in which the measurement result of the phase difference Δθ2 and the sign of the measurement result of the phase difference Δθ1 coincide with each other. A position locating method, wherein a phase difference Δθ2 is measured and obtained as a difference between the phase difference Δθ1 and the phase difference Δθ2 measured thereby. The position locating method according to claim 2,
The base station has the least influence degree of the multipath among the patterns for which the influence degree of the multipath is obtained, and the difference between the measured phase difference Δθ1 and the measured phase difference Δθ2 is the closest to zero. The position locating method characterized by selecting as said pattern. The position locating method according to claim 1,
The base station
The position of the mobile terminal is measured by measuring the phase difference Δθ1 and the phase difference Δθ2 using a measurement standard in which the measurement result of the phase difference Δθ2 is reversed in sign with respect to the measurement result of the phase difference Δθ1. In order to cancel out the errors included in each of the phase difference Δθ1 and the phase difference Δθ2, it is obtained by taking the difference between the phase difference Δθ1 and the phase difference Δθ2.
A position locating method, wherein the degree of influence of the multipath of the position locating signal received from the mobile terminal is obtained as a sum of the measured phase difference Δθ1 and phase difference Δθ2. The position locating method according to claim 4,
The base station determines the sum of the measured phase difference Δθ1 and the measured phase difference Δθ2 among the patterns for which the degree of multipath influence is obtained, for each of the measured phase difference Δθ1 and the phase difference Δθ2. A position locating method comprising: selecting a pattern closest to a sum of contained errors as the pattern having the least influence of the multipath. A position location method according to any one of claims 1 to 5,
The first antenna pair and the second antenna pair are arranged so that the antennas of the first antenna pair and the antennas of the second antenna pair are equidistantly spaced in a square shape on a plane. A location method characterized by: A system for locating a moving object,
A first antenna pair and a second antenna pair for receiving a position location signal, which is a radio signal for locating the position of the mobile terminal, transmitted from a mobile terminal provided in a mobile body;
The first antenna pair and the second antenna pair are a path difference of the positioning signal received by each antenna of the first antenna pair and the antenna received by each antenna of the second antenna pair. It is provided so that the path difference of the position location signal matches,
A direction in which the mobile terminal exists is obtained based on the phase difference Δθ of the positioning signals received by each antenna of the first antenna pair or each antenna of the second antenna pair, and based on the obtained direction A position locator that determines the position of the moving object;
A first phase difference measuring unit that obtains a phase difference Δθ1 of the positioning signals received by each antenna of the first antenna pair;
A second phase difference measuring unit that obtains a phase difference Δθ2 of the positioning signals received by each antenna of the second antenna pair;
A position location result output unit for outputting the position of the moving body;
A plurality of antennas capable of configuring a plurality of patterns of antenna groups including the first antenna pair and the second antenna pair;
A multipath evaluation information acquisition unit for determining the degree of multipath influence of the pattern based on the phase difference Δθ1 and the phase difference Δθ2 measured for each of the patterns;
A pattern selection unit that selects the pattern with the least influence of the multipath, and
The position locating result output unit outputs a position obtained based on the phase difference Δθ1 and the phase difference Δθ2 measured for the selected pattern as the position of the moving body. The location system according to claim 7,
The position locating unit calculates the phase difference Δθ1 and the phase difference Δθ2 by using a measurement standard in which the sign of the measurement result of the phase difference Δθ2 is inverted with respect to the measurement result of the phase difference Δθ1. Measured and obtained by taking the difference between the phase difference Δθ1 and the phase difference Δθ2 in order to cancel the error included in each of the measured phase difference Δθ1 and the phase difference Δθ2.
The multipath evaluation information acquisition unit indicates a degree of influence of the multipath of the positioning signal received from the mobile terminal, and a measurement standard in which the measurement result of the phase difference Δθ2 matches the measurement result of the phase difference Δθ1 The position difference system is characterized in that the phase difference Δθ1 and the phase difference Δθ2 are measured by using and the difference between the phase difference Δθ1 and the phase difference Δθ2 measured thereby is obtained. The position location system according to claim 8,
The pattern selection unit obtains the multipath influence degree that is the closest to the difference between the measured phase difference Δθ1 and the measured phase difference Δθ2 among the patterns for which the multipath influence degree is obtained. A positioning system characterized by selecting as a small number of the patterns. The location system according to claim 7,
The position locating unit calculates the phase difference Δθ1 and the phase difference Δθ2 by using a measurement standard in which the sign of the measurement result of the phase difference Δθ2 is inverted with respect to the measurement result of the phase difference Δθ1. Measured and obtained by taking the difference between the phase difference Δθ1 and the phase difference Δθ2 in order to cancel the error included in each of the measured phase difference Δθ1 and the phase difference Δθ2.
The multipath evaluation information acquisition unit obtains the degree of influence of the multipath of the location signal received from the mobile terminal as a sum of the measured phase difference Δθ1 and phase difference Δθ2. Orientation system. The position location system according to claim 10,
The pattern selection unit is configured so that a sum of the measured phase difference Δθ1 and the measured phase difference Δθ2 is the measured phase difference Δθ1 and the phase difference Δθ2 among the patterns for which the degree of multipath influence is obtained. A position locating system, wherein a pattern closest to a sum of errors included in the pattern is selected as the pattern having the least influence of the multipath. The position location system according to any one of claims 7 to 11,
The first antenna pair and the second antenna pair are arranged such that each antenna of the first antenna pair and each antenna of the second antenna pair are arranged in a square shape on a plane at equal intervals. A location system characterized by

Images