JP2008249675A - Method and device for estimating mobile station position - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and a device for estimating mobile station position with high accuracy. <P>SOLUTION: This method comprises an optimized base station set determining process for determining the optimized base station set which minimizes accuracy deterioration coefficient, with respect to the position in the movable region of a mobile station; a base station set identifying process for determining whether the selected base station set used for the calculation agrees with the optimized base station set corresponding to the position of the calculated mobile station, when the position of the mobile station is calculated by using the selected base station set which is one of the selected base station pairs; and a selected base station set changing process for changing the selected base station set to the optimized base station set, when it is determined that it does not agree with the base station set-identifying process. The position calculating of the mobile station is re-executed using the selected base station set changed by the selected base station set-changing process. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a highly accurate mobile station position estimation method for estimating the position of a mobile station when a plurality of base stations receive radio waves transmitted from the mobile station. This makes it possible to estimate the position with high accuracy even when a part of the information is not used.

  A system for detecting and tracking the position of a person or an object by using wireless communication has been proposed. For example, a system called a Global Positioning System (GPS). For example, as shown in Non-Patent Document 1, the GPS receives radio waves transmitted from a plurality of satellites by a single movable receiver, and based on the arrival time difference between the received radio waves, A system for detecting the position of a receiver.

  By the way, in the GPS, the position is detected by the receiver receiving the radio wave from the satellite at a known position, but conversely, the radio wave transmitted from one movable transmitter Similarly, it is possible to detect the position of the transmitter based on the radio waves received by the plurality of receivers received by a receiver fixed at a known position. For example, in Patent Document 2, a radio signal between a plurality of reference stations that are wireless devices whose positions are known and a detection target station that is a wireless device whose position is unknown is transmitted to one of the plurality of reference stations or the detection target stations. Measuring the physical quantity related to the distance to measure the absolute distance or relative distance between the reference station and the detection target station, and the distance measurement results that are the measured distances and the positions of the reference stations. Based on the above, a method for calculating the position of the detection target station is disclosed.

Takeyasu Sakai, “Introduction to GPS Technology”, Tokyo Denki University Press, February 2003 Japanese Patent Laid-Open No. 10-104333 JP 2006-090913 A

  A plurality of base stations installed in advance at predetermined positions receive radio waves transmitted from one movable mobile station, and the position of the mobile station is determined based on the radio waves received at these base stations. In the calculation method, the base station may be an existing wireless communication base station such as a wireless LAN (Local Area Network) base station or a PHS (Personal Handy-phone System) base station. At this time, the base station can be used by appropriately switching between a use for detecting the position of the mobile station and another use. Therefore, it may be assumed that some of the plurality of base stations are used for the purpose of detecting the position of the mobile station and the rest are used for other purposes. In general, the more base stations used for detecting the position of the mobile station, the more accurate the detection becomes possible. Therefore, when the number of base stations is reduced, the accuracy of detecting the position of the mobile station decreases. Therefore, in such a case, there is a need for a method for selecting a base station used for detecting the position of a mobile station, which can be detected with the highest possible accuracy even when the number of base stations used for detecting a mobile station is reduced. Become.

  The GPS detects all combinations of a predetermined number of visible satellites for each observation time point based on the result of simulation, calculates the positioning accuracy of the predetermined number of visible satellites included in each detected combination, and observes A data table is created and stored for one observation point and a data set corresponding to the time point, the combination of visible satellites, and the positioning accuracy is stored and held, and if a satellite failure is assumed, it is included in the data table While calculating the positioning accuracy under any failure situation by detecting the best positioning accuracy at each observation time from the remaining data sets excluding the data set including the failed satellite in the data set, A technique for calculating the effectiveness of a positioning system based on the positioning accuracy is disclosed in Patent Document 1. However, the technique described in Patent Document 1 is the most of the remaining combinations except for a combination including a failed satellite from all combinations of a predetermined number of visible satellites that are determined in advance by simulating the flight situation of the satellites. This system detects a combination of satellites with high positioning accuracy, and is used for other purposes in a system in which a plurality of fixed stations receive radio waves emitted from mobile stations and detect their positions as in the present invention. This is different from the case where the number of base stations is reduced.

[First Means for Solving the Problems]
The gist of the invention according to claim 1 for solving such a problem is that: (a) a plurality of base stations in which radio waves transmitted from a mobile station moving in a predetermined movable area are previously set at predetermined positions; And a mobile station position calculating step of calculating the position of the mobile station based on radio waves received by the base station set, the movement in the mobile station position calculating step A mobile station location estimation method in the case where there are more base stations than the minimum number of the base stations constituting the base station set necessary for calculating the location of the station, and (b) movement of the mobile station The base corresponding to the position in the possible area and having the smallest accuracy degradation coefficient, which is a coefficient representing the degradation of precision when used for calculating the position of the mobile station from the plurality of base stations in the mobile station position calculation step Optimum base that is a station group An optimal base station set determining step for determining a station set; and (c) a predetermined base station set by a mobile station position calculating step using a selected base station set that is one base station set selected from the base station set. When the position is calculated, the selected base station set used in the mobile station position calculating step is determined by the optimum base station set determining step corresponding to the position of the mobile station calculated by the mobile station position calculating step. A base station set verification step for determining whether or not the optimum base station set matches, and (d) in the verification by the base station set verification step, the selected base station set and the optimum base station set are: A step of changing the selected base station set to change the selected base station set used in the mobile station position calculating step to the optimum base station set when the mobile station position is not matched, and (e) the mobile station position The calculating step includes selecting the selected base station group Performing a position calculating again the mobile station using have been changed by further processing selected base station sets, characterized by.

[Effect of the first invention]
In this way, the optimum base station set determination step determines the optimum base station set that is the base station set that minimizes the accuracy degradation coefficient for each position of the mobile station in the movable region. By the base station group matching step, the selected base station group used by the mobile station position calculating step and the optimum base station group determining step corresponding to the position of the mobile station calculated by the mobile station position calculating step When it is determined whether or not the determined optimal base station set matches, and when it is determined that the selected base station set and the optimal base station set do not match in the verification by the base station set verification step The selected base station set changing step changes the selected base station set used in the mobile station location calculating step to the optimum base station set, and the mobile station location calculating step changes the selected base station Since the position calculation of the mobile station is performed again using the selected base station group changed by the group changing step, that is, the optimum base station group corresponding to the position of the mobile station calculated by the mobile station position calculation means. Thus, the position of the mobile station can be estimated with high accuracy.

  Here, preferably, the optimum base station set determining step stores the optimum base station set associated with coordinates in the movable area in an optimum base station set table. According to this configuration, the optimum base station set determination step uses the selected base station set to obtain the optimum base station set corresponding to the mobile station position calculated by the mobile station position calculation step from the optimum base station set table. Since it is determined by reading, quick calculation is possible.

  Also preferably, the optimum base station set determining step (a) calculates all base station sets composed of the plurality of base stations, and (b) sets a plurality of preset base stations in the movable area. At each reference point, the accuracy degradation coefficient is calculated when the position of the mobile station is calculated using one base station set of all the base station sets, and the accuracy degradation coefficient is calculated as the reference degradation coefficient. The accuracy degradation coefficient table stored in association with the coordinates of the points is created for all of the base station groups, and (c) a plurality of created for all of the base station groups at each of the reference points Among the accuracy degradation coefficient tables, the base station group used when creating the accuracy degradation coefficient table with the smallest accuracy degradation coefficient at the reference point is associated with the coordinates of the reference point and the optimum base station Assembly table It characterized in that it saved to. In this way, it is possible to create the optimum base station set table that minimizes the accuracy degradation coefficient for each of the reference points.

  Preferably, the mobile station location estimation method uses a change of the selected base station set used in the mobile station location calculation step by the selected base station set changing step and another changed selected base station set. The calculation of the position of the mobile station again in the mobile station position calculation step is repeatedly performed until it is determined in the base station group matching step that the selected base station group and the optimum base station group match. The According to this configuration, since the position of the mobile station calculated by the mobile station position calculation step matches the optimum base station set corresponding to the position of the mobile station, the position of the mobile station with higher accuracy can be determined. Estimation is possible.

  Preferably, the determination of the optimum base station group by the optimum base station group determination step is executed in advance for a plurality of positions set in advance in the movable area of the mobile station. In this way, since the optimum base station set is determined in advance for a plurality of positions in the movable region, the optimum mobile station position is calculated even in the first mobile station position calculation by the mobile station position calculation step. In the base station group determination step, the optimum base station group corresponding to the calculated position of the mobile station is determined.

  Preferably, the determination of the optimal base station set by the optimal base station set determination step is calculated to be the position of the mobile station each time the position of the mobile station is calculated by the mobile station position calculation step. It is executed for the point where In this way, since the determination of the optimal base station set is performed for the part calculated as the position of the mobile station every time the position of the mobile station is calculated by the mobile station position calculation step, It is not necessary to execute the optimum base station set determination step in advance.

  Preferably, the optimum base station set determined by the optimum base station set determining step is configured by the base station that can be used in the mobile station position calculating step. In this way, the optimum base station group is constituted by the base stations that can be used in the mobile station position calculating step, so that the optimum base station cannot be actually used.

  Preferably, when the estimation of the position of the mobile station by the mobile station position estimation method is repeatedly performed, the optimum base station set used in the immediately preceding mobile station position estimation method is the selected base station set. Used by the base station verification process. In this way, when the moving speed of the mobile station is slow, the selected base station set becomes the optimum base station set at the time of the repeated execution when the mobile station position estimation method is repeatedly executed. Therefore, it may not be necessary to perform the position calculation again in the mobile station position calculation step, and the time required for position estimation can be shortened.

  Preferably, the mobile station is a plurality of mobile stations, and the selection of the selected base station set and the determination of the optimum base station set are executed for each mobile station of the plurality of mobile stations. In this way, even if there are a plurality of mobile stations, the position is calculated sequentially for each mobile station.

  Preferably, in the mobile station position estimation method, (a) when a part of the plurality of base stations fails, the position of the mobile station is detected by a normal base station excluding the part of the failed base stations. (B) when it is determined that the position of the mobile station can be estimated by the failure determination step, the selected base station group And selection of the optimum base station set is performed from the normal base station. In this way, even if a part of the plurality of base stations fails due to the failure determination step, the position of the mobile station is estimated by a normal base station excluding the part of the failed base stations. If it is determined that the position of the mobile station can be estimated by the failure determination step, the selection of the selected base station set and the determination of the optimum base station set are as follows: Since this is performed from the normal base station, the position of the mobile station can be estimated.

  Preferably, the optimum base station set determining step uses a plurality of combinations of the selected base station sets for calculating the position of the mobile station by the mobile station position calculating step using the selected base station set. In the case where there is an error, the ranks are ranked in ascending order of accuracy degradation coefficients, and among the selected base station groups not including the failed part of the base stations, the highest base station group is determined as the optimum base station group. In this way, even when some of the plurality of base stations fail, the highest rank among the selected base station sets not including the failed base station, that is, the accuracy degradation coefficient is small. Since the optimum base station group is used, it is possible to estimate the position with high accuracy even when a part of the plurality of base stations fails.

  Preferably, in the mobile station position estimation method, (a) the position of the mobile station calculated by the mobile station position calculation step is determined by the optimal base station set determination step with respect to the position of the mobile station. Boundary for determining whether or not the optimum base station set to be determined and the optimum base station set determined by the optimum base station set determination step are in different boundary regions with respect to the vicinity of the position of the mobile station And (b) when it is determined by the boundary determination step that the position of the mobile station is in the boundary area, the position of the mobile station is determined in consideration of an optimal base station group in the boundary area. And a boundary vicinity mobile station position calculating step for calculating. In this way, the optimum base station set can be determined even when the position of the mobile station calculated by the mobile station position calculating step is in the boundary region.

  Preferably, (a) the optimum base station group determining step attaches an optimum base station group related value related to the optimum base station group for each determined optimum base station group; The boundary determination step is based on a weighted average of the optimum base station set-related values corresponding to the optimum base station set determined by the optimum base station set decision step at the determined mobile station position and in the vicinity. And determining whether or not the mobile station position is at the boundary. In this way, it is determined whether or not the mobile station position is at the boundary based on a weighted average of the optimum base station group-related values corresponding to a plurality of optimum base station groups existing in the boundary region. .

  Preferably, the boundary determination step occurs at the time of positioning of the mobile station in which the size of the boundary area is generated according to specifications of the mobile station, the plurality of base stations, and the mobile station position estimation method. Determine based on error. In this way, the boundary region can be determined in consideration of the error.

  Preferably, in the boundary determination step, the boundary region is located outside the movable region when the boundary region exists both inside the movable region and outside the movable region. Weighting is performed without considering the optimum base station group related value. In this way, the boundary determination step calculates the position of the mobile station near the boundary even when the boundary area exists across both the inside of the movable area and the outside of the movable area. According to the process, the position of the mobile station can be estimated.

[Second Means for Solving the Problems]
Further, the gist of the invention according to claim 16 for solving such a problem is that: (a) a plurality of radio waves transmitted in advance from a mobile station moving in a predetermined movable area are installed at predetermined positions; A mobile station position calculating means for receiving a base station set comprising a combination of base stations and calculating the position of the mobile station based on radio waves received by the base station set; A mobile station position estimation apparatus in the case where there are more base stations than the minimum number of the base stations constituting the base station set necessary for calculating the position of the mobile station, and (b) the mobile station Corresponding to the position in the movable area of the mobile station, the accuracy degradation coefficient, which is a coefficient representing degradation in accuracy, is used when the mobile station position calculation means calculates the position of the mobile station from the plurality of base stations. In the base station group (C) a predetermined movement by the mobile station position calculating means using a selected base station set which is one base station set selected from the base station set; When the position of the station is calculated, the selected base station set used by the mobile station position calculating means and the optimum base station set determining means corresponding to the position of the mobile station calculated by the mobile station position calculating means Base station set verification means for determining whether or not the determined optimal base station set matches, and (d) in the verification by the base station set verification means, the selected base station set and the optimal base station set The base station set changing means for changing the selected base station set used in the mobile station position calculating means to the optimum base station set when (e) the mobile The station position calculation means is the selection Performing a re-position calculation of the mobile station using the selected base station sets that have been modified by the earth station set changing means, characterized by.

[Effect of the second invention]
In this way, the optimum base station set determining means determines the optimum base station set that is the base station set that minimizes the accuracy degradation coefficient for each position in the movable area of the mobile station, Corresponding to the selected base station set used by the mobile station position calculating means by the base station set checking means and the position of the mobile station calculated by the mobile station position calculating means by the optimum base station set determining means When it is determined whether or not the determined optimum base station set matches, and it is determined that the selected base station set and the optimum base station set do not match in the check by the base station set check means The selected base station set changing means changes the selected base station set used in the mobile station position calculating means to the optimum base station set, and the mobile station position calculating means changes the selected base station Since the position calculation of the mobile station is executed again using the selected base station group changed by the group changing means, that is, the optimum base station set corresponding to the position of the mobile station calculated by the mobile station position calculating means. Thus, the position of the mobile station can be estimated with high accuracy.

  Preferably, the optimum base station set determining means stores the optimum base station set associated with coordinates in the movable area in an optimum base station set table. In this way, the optimum base station set determining means uses the selected base station set to obtain the optimum base station set corresponding to the mobile station position calculated by the mobile station position calculating means from the optimum base station set table. Since it is determined by reading, quick calculation is possible.

  Also preferably, the optimum base station set determining means (a) calculates all base station sets composed of the plurality of base stations, and (b) a plurality of preset base stations in the movable area. At each reference point, the accuracy degradation coefficient is calculated when the position of the mobile station is calculated using one base station set of all the base station sets, and the accuracy degradation coefficient is calculated as the reference degradation coefficient. The accuracy degradation coefficient table stored in association with the coordinates of the points is created for all of the base station groups, and (c) a plurality of created for all of the base station groups at each of the reference points Among the accuracy degradation coefficient tables, the base station group used when creating the accuracy degradation coefficient table with the smallest accuracy degradation coefficient at the reference point is associated with the coordinates of the reference point and the optimum base station Assembly table It characterized in that it saved to. In this way, it is possible to create the optimum base station set table that minimizes the accuracy degradation coefficient for each of the reference points.

  Preferably, the position estimation device uses the selected base station set changing means by the selected base station set changing means used in the mobile station position calculating means, and the changed other selected base station set is used. The calculation of the position of the mobile station again by the mobile station position calculation means is repeatedly performed until the base station set verification means determines that the selected base station set matches the optimum base station set. In this way, since the position of the mobile station calculated by the mobile station position calculation means matches the optimum base station set corresponding to the position of the mobile station, the position of the mobile station with higher accuracy can be determined. Estimation is possible.

  Preferably, the determination of the optimum base station set by the optimum base station set determination means is executed in advance for a plurality of positions set in advance in the movable area of the mobile station. In this way, since the optimum base station set is determined in advance for a plurality of positions in the movable area, the optimum position is calculated even when the mobile station position calculation means calculates the position of the mobile station for the first time. The base station set determining means determines an optimal base station set corresponding to the calculated position of the mobile station.

  Preferably, the determination of the optimum base station set by the optimum base station set determining means is calculated to be the position of the mobile station every time the position of the mobile station is calculated by the mobile station position calculating means. It is executed for the point where In this way, since the determination of the optimum base station set is performed for the part calculated as the position of the mobile station every time the position of the mobile station is calculated by the mobile station position calculation means, There is no need to execute the optimum base station group determining means in advance.

  Preferably, the optimum base station group determined by the optimum base station group determining unit is configured by the base station that can be used in the mobile station position calculating unit. In this way, the optimum base station group is constituted by the base stations that can be used in the mobile station position calculating means, so that the optimum base station cannot be actually used.

  Preferably, in the case where the estimation of the position of the mobile station is repeatedly performed by the position estimation device, the optimum base station set used in the immediately preceding position estimation device is the base station verification as the selected base station set. Used by means. In this way, when the moving speed of the mobile station is slow, etc., when the position estimation device is repeatedly executed, the selected base station set becomes the optimum base station set at the time of the repeated execution, There is a case where it is not necessary to perform position calculation again by the mobile station position calculating means, and the time required for position estimation can be shortened.

  Preferably, the mobile station is a plurality of mobile stations, and the selection of the selected base station set and the determination of the optimum base station set are executed for each mobile station of the plurality of mobile stations. In this way, even if there are a plurality of mobile stations, the position is calculated sequentially for each mobile station.

  Preferably, the position estimation device is configured to (a) estimate a position of a mobile station by a normal base station excluding the part of the failed base stations when a part of the plurality of base stations fails. And (b) if it is determined by the failure determination means that the position of the mobile station can be estimated, the selection of the selected base station set is performed. The determination of the optimum base station set is performed from the normal base station. In this way, even when a part of the plurality of base stations fails, the position of the mobile station is estimated by a normal base station excluding the part of the failed base stations. If the failure determination means determines that the position of the mobile station can be estimated, the selection of the selected base station set and the determination of the optimal base station set are as follows: Since this is performed from the normal base station, the position of the mobile station can be estimated.

  Preferably, the optimum base station set determining means uses a plurality of combinations of the selected base station sets for calculating the position of the mobile station by the mobile station position calculating means using the selected base station set. In the case where there is an error, the ranks are ranked in ascending order of accuracy degradation coefficients, and among the selected base station groups not including the failed part of the base stations, the highest base station group is determined as the optimum base station group. In this way, even when some of the plurality of base stations fail, the highest rank among the selected base station sets not including the failed base station, that is, the accuracy degradation coefficient is small. Since the optimum base station group is used, it is possible to estimate the position with high accuracy even when a part of the plurality of base stations fails.

  Preferably, the position estimation device is configured such that (a) the position of the mobile station calculated by the mobile station position calculation unit is determined by the optimum base station set determination unit with respect to the position of the mobile station. Boundary determining means for determining whether or not the optimum base station set and the optimum base station set determined by the optimum base station set determining means are in a different boundary region with respect to the vicinity of the position of the mobile station And (b) when the boundary determination means determines that the position of the mobile station is in the boundary area, the position of the mobile station is calculated in consideration of the optimum base station group in the boundary area. It has a boundary vicinity mobile station position calculation means. In this way, the optimum base station set can be determined even when the position of the mobile station calculated by the mobile station position calculating means is in the boundary region.

  Preferably, (a) the optimum base station set determining means attaches an optimum base station set related value related to the optimum base station set to each determined optimum base station set; The boundary determination means is based on a weighted average of the optimum base station set-related values corresponding to the optimum base station set determined by the optimum base station set decision means at the determined mobile station position and in the vicinity. And determining whether or not the mobile station position is at the boundary. In this way, it is determined whether or not the mobile station position is at the boundary based on a weighted average of the optimum base station group-related values corresponding to a plurality of optimum base station groups existing in the boundary region. .

  Preferably, the boundary determination means determines the size of the boundary area as an error generated during positioning of the mobile station, which occurs due to specifications of the mobile station, the plurality of base stations, and the position estimation device. Determine based on. In this way, the boundary region can be determined in consideration of the error.

  In addition, preferably, the boundary determination means, when the boundary area exists across both the inside of the movable area and the outside of the movable area, the outside of the movable area Weighting is performed without considering the optimum base station group related value. In this way, the boundary determination means calculates the position of the mobile station in the vicinity of the boundary even when the boundary area exists across both the inside of the movable area and the outside of the movable area. The position of the mobile station can be estimated by means.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a diagram showing an overview of a system to which a mobile station position estimation method of the present invention is applied. In FIG. 1, a movable region 50 formed of a square having a side 30 (m) is provided as a movable region 50 provided in an arbitrary shape on a plane. The movable area 50 includes four base stations, a first base station 12A, a second base station 12B, and a third base station, as the base station 12 having a function of performing wireless communication with the mobile station 10 described later. 12C and a fourth base station 12D are provided. As will be described later, at least three base stations are required for the calculation of the position of the mobile station 10 on the plane based on the propagation time of radio waves, as will be described later. Accordingly, at any point in the movable area, the base station is arranged so that at least the mobile station can communicate with the three base stations. Further, the position of the mobile station can be calculated more accurately as the number of base stations increases. In FIG. 1, one base station 12A to 12D is arranged at each of the four corners of a square movable area 50, which satisfies this requirement. Further, the mobile station 10 is arranged in the movable area 50 and is movable in the movable area 50. In FIG. 1, two mobile stations 10A and 10B are arranged as an example. Note that the number of mobile stations is not particularly limited. In addition, a positioning server 14 is provided that is communicable with the base station 12 by, for example, a wired cable 52, and the mobile station 10 transmits the mobile station 10 based on radio waves transmitted by the mobile station 10 and received by the base station 12. The position of the base station 10 in the possible area is calculated. In the present specification, the mobile stations 10A and 10B are indicated as mobile stations 10 when not distinguished from each other, and the base stations 12A through 12D are indicated as base stations 12 when not distinguished from each other.

  At this time, the x-axis and the y-axis are defined for the movable area 50 as shown in FIG. 2 for convenience, and the coordinates of the points on the movable area 50 are defined based on these axes. That is, the first base station 12A is on the coordinates (0, 0), the second base station 12B is on the coordinates (0, 30), the third base station 12C is on the coordinates (30, 30), and the fourth base station The stations 12D are respectively arranged on the coordinates (30, 0). Further, the movable region 50 can be considered, for example, as shown in FIG. 2 by dividing it into a grid with squares having a side of 1 (m). At this time, the length of one side of the square used for the division is determined based on, for example, the positioning accuracy or the processing time of the computer in the positioning server 14 or the like. Each square constituting the lattice is referred to as a cell 54.

  FIG. 3 is a functional block diagram showing an outline of the configuration of the mobile station 10 and the base station 12. The mobile station 10 and the base station 12 have substantially the same functional configuration as shown in FIG. The antenna unit 20 is used for transmitting and receiving radio waves, and the balanced / unbalanced converting unit 22 is a balun, and converts the unbalanced line of the transmission / reception switching unit 24 into a balanced line so as to be compatible with the antenna unit 20. The controller 401 is a control circuit composed of a known microcomputer and its peripheral circuits, and controls the operation of the mobile station 10 by controlling a transmission / reception switching unit 24 and the like which will be described later.

  The transmission / reception switching unit 24 switches between the transmission state and the reception state of the mobile station 10 or the base station 12. That is, when the transmission / reception switching unit 24 switches the mobile station 10 or the base station 12 to the transmission state, the mobile station 10 or the base station 12 functions as a transmitter, and when switching to the reception state, the mobile station 10 or the base station 12 functions as a receiver. It is done. In addition, when the mobile station 10 or the base station 12 is caused to function as a transmitter by the transmission / reception switching unit 24, the transmission amplifier unit 26 amplifies a signal wave generated by the radio unit 28 described later.

  When the mobile station 10 or the base station 12 is caused to function as a transmitter, the radio unit 28 converts a signal generated by the control unit 32 described later into a format for performing wireless communication, and the mobile station 10 or the base station 12 When the station 12 is caused to function as a receiver, the station 12 converts the received wave received by the antenna unit 20 into a signal to be processed by the control unit 32, and is implemented by, for example, an IC. Specifically, the radio unit 28 includes a PLL circuit (phase lock loop) circuit, a VCO (Voltage Controlled Oscillator) circuit, a digital modulation demodulator 30 and the like that generate a carrier wave of a predetermined frequency according to a command from the controller 401. The digital modulation demodulator 30 digitally modulates the signal generated by the control unit 32 and demodulates the received signal received, and outputs the generated digital data to the control unit 32 so that the mobile station 10 and the base station Wireless communication with 12 is performed by digital communication.

  The control unit 32 includes a spectrum spreading unit 34, a despreading processing unit 341, a baseband signal generation / restoration unit 36, a spreading code generation unit 38, and the like, and is implemented by, for example, a gate array or a microcomputer having these functions. Of these, the baseband signal generation / restoration unit 36 encodes information to be transmitted and generates a baseband signal when the mobile station 10 or the base station 12 functions as a transmitter. When the mobile station 10 or the base station 12 is caused to function as a receiver, the transmitted information is extracted from the baseband signal decoded by despreading by the despreading processing unit 341 described later.

  The spread code generator 38 generates a spread code for performing spread spectrum by the spread spectrum unit 34 described later. As this spreading code, the autocorrelation function has a high peak, i.e., when the phase difference is zero, the autocorrelation has a large value, whereas when the phase difference is not zero, the autocorrelation is sufficiently small, and A code string that satisfies the condition that the correlation between codes is sufficiently small in all phase differences, that is, the cross-correlation is small is used. Specifically, for example, an M-sequence code or a Gold sequence code that is also used in GPS is used. This Gold sequence code is also called a pseudo-noise code (PN signal).

  When the mobile station 10 or the base station 12 is caused to function as a transmitter, the spread spectrum unit 34 has the baseband signal generated by the baseband signal generation / restoration unit 36 generated by the spreading code generation unit 38. Spread spectrum is performed using a spread code to generate a signal for transmission. Specifically, for example, a direct spread method using an exclusive OR of the baseband signal and the spreading code as a result is used. In addition, when the mobile station 10 or the base station 12 is caused to function as a receiver, the despreading processing unit 341 performs spectrum despreading using the received wave demodulated by the digital modulation / demodulation unit 30 and the spreading code. To extract the baseband signal. In the case of this reception, the same spreading code as in the case of transmission is used. Using such spread spectrum, when communication between a specific mobile station and a base station is performed using a specific spread code, other mobile stations and base stations at the same time and at the same frequency Even when the communication with is performed using another spreading code, the mutual communication is not affected.

  The power supply unit 40 supplies necessary power to the transmission amplifier 26, the radio unit 28, the control unit 32, and the like described above. The clock 41 supplies time information that is referred to when a radio wave is transmitted or received.

The distance measuring unit 42 is provided in the base station 12, and based on the time difference between the radio wave transmitted by the mobile station 10 and the radio wave received by the base station 12, that is, the time required for the radio wave to reach, The distance to the base station 12 is measured. The distance measuring unit 42 includes, for example, a matched filter, and specifically includes a replica code generating unit 44, a delay circuit 46, a correlation calculating unit 50, and the like. In the replica code generation unit 44, the mobile station 10 generates a replica code that is the same code as the spread code generated by the spread code generation unit 38 and used in the spectrum spread unit 34. Then, in the delay circuit 46 constituted by a known shift register, a signal wave in a radio wave transmitted by the mobile station 10 and received by the base station 12 is input and delayed at a plurality of predetermined intervals. . Then, in the correlation calculation unit 50, a correlation coefficient between the received wave delayed by the delay circuit 46 and the replica code is calculated. As a result, the reception time when the calculated correlation coefficient becomes maximum is set as the arrival time of the radio wave from the mobile station 10. Since the transmission time by the mobile station 10 is obtained by restoring the baseband signal by the baseband signal creation / restoration unit 36, the time difference between the arrival time and the transmission time of the radio wave is calculated, and the radio wave velocity c (2.997) is calculated. The distance from the mobile station 10 is calculated by multiplying × 10 ⁸ (m / s)). In addition, when used as the base station 12, a wired communication unit 43 for performing communication with the positioning server 14 to be described later is provided. For example, the data is transmitted to the positioning server 14 connected by a wired cable 52 such as a LAN cable. Transmission / reception is possible.

  The positioning server 14 includes, for example, a so-called computer having a CPU, RAM, ROM, input / output interface, and the like, and performs signal processing according to a program stored in the ROM in advance using the temporary storage function of the RAM. Thus, calculation of the position of the mobile station 10, that is, positioning is executed.

  FIG. 4 is a functional block diagram for explaining the control operation of the positioning server 14. The positioning server 14 includes an I / F (interface) unit 106 for exchanging data with the base station 12 via a wired cable 52, a position calculation unit 56, a base station combination information holding unit 100, a DOP map creation holding unit 102, a base station combination determination unit 104, and the like.

First, in the position calculation unit 56 corresponding to the mobile station position calculation step or the mobile station position calculation means, for example, based on the distance between the base station and the mobile station calculated by the plurality of base stations 12, The position of the mobile station 10 is calculated. Specifically, for example, when the movable region 50 is a plane as shown in FIG. 1, the coordinates of the first base station 12A are (x ₁ , y ₁ ) and the coordinates of the second base station 12B are (x ₂ , y ₂ ), the coordinates of the third base station 12 C are (x ₃ , y ₃ ), the distance between the first base station 12 A and the mobile station 10 measured by the first base station 12 A is r ₁ , 2 The distance between the second base station 12B measured by the base station 12B and the mobile station 10 is r ₂ , the distance between the second base station 12C measured by the third base station 12C and the mobile station 10 is r ₃ , and the mobile station (X, y) and the error s based on the time lag of the clock 41 that each of the mobile station 10 and the base station 12 has, as shown in FIG.
(X−x ₁ ) ² + (y−y ₁ ) ² = (r ₁ + s) ² ,
(X−x ₂ ) ² + (y−y ₂ ) ² = (r ₂ + s) ² , (1)
(X−x ₃ ) ² + (y−y ₃ ) ² = (r ₃ + s) ² ,.
There is a relationship represented by At this time, the clock of the clock 41 included in each of the first base station 12A, the second base station 12B, and the third base station 12C is synchronized by, for example, a method described later, and the error s is common to each base station. is there. At this time, since there are three variables x, y, and s and the above three equations, the values of x, y, and s are calculated by solving these three expressions by, for example, the Newton-Raphson method. It is possible. Note that, as described above, the distance between the first base station 12A to the third base station 12C and the mobile station 10 obtained by measurement by the distance measuring unit 42 included in each of the first base station 12A to the third base station 12C. r ₁ , r ₂ , and r ₃ are so-called pseudoranges in which the error s based on the time lag of the clock 41 of each of the mobile station 10 and the base station 12 is not considered. Instead of the distances r ₁ , r ₂ , and r ₃ , accurate distances in which the error s based on the clock deviation is corrected may be used.

  Thus, when the movable region 50 is a plane, there are three variables. Therefore, if there are at least three expressions, the values of these variables are calculated, and this is the minimum of three base stations 12. Means that the position of the mobile station 10 can be calculated. On the other hand, when there are four or more base stations, it is possible to calculate the position of the mobile station 10 with higher accuracy by using a least square method that minimizes an error in the calculation.

  FIG. 6 is a time chart showing an example of a procedure for synchronizing the clocks 41 of the four base stations 12. In this figure, the state of communication between each base station and the positioning server is shown by arrows connecting the first base station 12A to the fourth base station 12D and the positioning server 14 in the horizontal direction represented by vertical lines. Yes. The direction of the arrow indicates the direction of communication, and the device to which the arrow is pointing is the receiving side. An arrow indicated by a broken line indicates wireless communication. Also, the time axis is taken downward in the figure, and the time progresses as it goes down.

  First, at time t1, the positioning server 14 issues a command for searching for an empty channel in wireless communication to any one base station 12 (the first base station 12A in the figure). In response to this, the first base station 12A performs a channel scan, and transmits information on the found empty channel to the positioning server 14 at time t2. Subsequently, at time t3, the positioning server 14 issues an instruction to wirelessly transmit time information to any one base station 12 (first base station 12A in the figure). Further, from time t4 to time t6, time information is sequentially transmitted from the positioning server 14 to each of the base stations other than the arbitrary one base station (second base station 12B to fourth base station 12D in this figure). A command to receive is issued. Subsequently, at time t7, time information from the first base station 12A, that is, time information of the clock 41 of the first base station 12A is transmitted by radio, and is received by the second base station 12B to the fourth base station 12D by radio. The Furthermore, the time information received by each of the second base station 12B to the fourth base station 12D from time t8 to time t10, that is, the time of the first base station and the second base at the time of transmission transmitted by the first base station 12A. Information including the time received by each of the stations 12B to 4D is sequentially transmitted to the positioning server by the wired communication unit 43.

  Here, since the position of each base station 12 is known, each propagation required for the radio wave transmitted from the first base station 12A to reach each of the second base station 12B to the fourth base station 12D. The time is calculated in advance. Therefore, for each of the second base station 12B to the fourth base station 12D, a value obtained by subtracting the propagation time from the time of the reception time and the time of the transmission from the first base station 12A is the second base station 12B to the fourth base station 12B. There is a time lag between the clock 41 of the base station 12D and the clock 41 of the first base station 12A. The clock 41 of each base station 12 is synchronized by correcting the clock 41 of the second base station 12B to the fourth base station 12D from time t11 to time t13 so that the calculated time lag is eliminated. The

  FIG. 7 is a time chart for calculating the distance r between each base station 12 and the mobile station 10 used by the position calculation unit 56. In this figure, the state of communication between each base station and the positioning server by arrows connecting the first base station 12A to the fourth base station 12D and the positioning server 14 and the mobile station 10 in the horizontal direction represented by vertical lines. It is shown. The direction of the arrow indicates the direction of communication, and the device to which the arrow is pointing is the receiving side. An arrow indicated by a broken line indicates wireless communication. Also, the time axis is taken downward in the figure, and the time progresses as it goes down.

  First, at time t1, the positioning server 14 issues a command for searching for an empty channel in wireless communication to any one base station 12 (the first base station 12A in the figure). In response to this, the first base station 12A performs a channel scan, and transmits information on the found empty channel to the positioning server 14 at time t2. Subsequently, at time t3, an instruction to wirelessly transmit an instruction to wirelessly transmit time information to the mobile station 10 from the positioning server 14 to any one base station 12 (first base station 12A in the figure). Is done. In response to this, at time t4, the first base station 12A transmits to the mobile station 10 a command for wirelessly transmitting time information. Further, from time t5 to time t8, the positioning server 14 issues a command to sequentially receive time information by radio to each of all base stations (first base station 12A to fourth base station 12D in the figure). . Subsequently, at time t9, time information from the mobile station 10, that is, time information of the clock 41 of the mobile station 10, is transmitted by radio and is received by the first base station 12A to the fourth base station 12D by radio. Based on this received signal, the distance measuring unit 42 of each base station 12 calculates the distance between each base station 12 and the mobile station 10, and from time t10 to time t13, the first base station 12A to fourth base station 12D. The calculated distance r between each of the base stations 12 and the mobile station 10 is transmitted to the positioning server 14 by the wired communication unit 43.

  The distances r1 to r4 between the first base station 12A to the fourth base station 12D and the mobile station 10 thus obtained and the position information of each base station given in advance are substituted into the equation (1). As a result of solving Equation (1) by the Newton-Raphson method or the least square method, the position coordinates (x, y) of the mobile station 10 are calculated.

  Incidentally, as described above, when the movable area 50 of the mobile station 10 is a plane, the number of base stations 12 required for calculating the position is at least three. When there are four or more base stations, the position of the mobile station 10 can be calculated using all of the base stations 12, while at least three of the base stations 12 are included. It is also possible to calculate the position of the mobile station 10 using the above. However, when the position of the mobile station 10 is calculated using a part of the base station 12, the position detection accuracy of the mobile station 10 may deteriorate depending on the combination of a part of the base station 12. Therefore, for example, when an existing wireless communication base station such as a wireless LAN (Local Area Network) base station or a PHS (Personal Handy-phone System) base station is used as the base station 12, a part of the mobile station is used as a mobile station. For example, when the remaining position is used as a wireless LAN base station for use as a base station 12 for detecting the position of the mobile station 10, the mobile station 10 has the highest accuracy in calculating the position of the mobile station 10. It is necessary to select the base station 12 used for the calculation of the position.

  In the present embodiment, as shown in FIG. 1, when there are four base stations 12 of the first base station 12A to the fourth base station 12D, a mobile station using three of these four base stations 12 is used. The selection of a base station when it is desired to execute calculation of 10 positions will be described as an example.

ここで、（ｘ１，ｙ１）は第１基地局１２Ａの座標、（ｘ２，ｙ２）は第２基地局１２Ｂの座標、（ｘ３，ｙ３）は第３基地局１２Ｃの座標、ｒ１は第１基地局１２Ａが測定した第１基地局１２Ａと移動局１０との距離、ｒ２は第２基地局１２Ｂが測定した第２基地局１２Ｂと移動局１０との距離を、ｒ３は第３基地局１２Ｃが測定した第２基地局１２Ｃと移動局１０との距離であり、（ｘ，ｙ）が算出された移動局１０の座標である。このＤＯＰが小さいほど、正確な測位が実行できている指標となる。 By the way, DOP (Dilution of Precision) is one of the accuracy degradation coefficients which is a number representing an index of positioning accuracy. This DOP is a number representing the relationship between the measurement accuracy of the distance between the mobile station 10 and the base station 12, that is, the ranging accuracy, and the measurement accuracy of the position of the mobile station, that is, the positioning accuracy.
(Ranging accuracy) x (DOP) = (Positioning accuracy)
It is. When the mobile station 10 moves on a plane, an HDOP (Horizontal DOP) that is a DOP for positioning accuracy in the horizontal direction is used. HDOP is defined as follows.

Here, (x1, y1) are the coordinates of the first base station 12A, (x2, y2) are the coordinates of the second base station 12B, (x3, y3) are the coordinates of the third base station 12C, and r1 is the first base station The distance between the first base station 12A measured by the station 12A and the mobile station 10, r2 the distance between the second base station 12B measured by the second base station 12B and the mobile station 10, and r3 the distance measured by the third base station 12C. It is the measured distance between the second base station 12C and the mobile station 10, and (x, y) is the calculated coordinates of the mobile station 10. The smaller this DOP, the more accurate the positioning is.

  At each coordinate, the HDOP value is calculated corresponding to the combination of base stations used for positioning. Here, FIG. 8 shows the minimum value of HDOP in the height direction for each coordinate of the movable area 50. As shown in this figure, the curved surface representing the minimum value of HDOP is composed of four different curved surfaces, and these curves are in contact with each other by a ridge line-shaped curve 58. These four curved surfaces are respectively a selection method for selecting three base stations from four base stations, that is, base stations that perform positioning of the mobile station 10, respectively, the first base station 12A, the second base station 12B, and A combination of the third base station 12C, a combination of the first base station 12A, the second base station 12B and the fourth base station 12D, a combination of the first base station 12A, the third base station 12C and the fourth base station 12D, a second This corresponds to a combination of the base station 12B, the third base station 12C, and the fourth base station 12D. In FIG. 8, only the curved surface that minimizes HDOP is drawn among the four curved surfaces that overlap each other for each position of the movable region 50. Thus, it can be seen that the combination of base stations that minimizes HDOP differs depending on the position of the movable region 50. FIG. 9 is a plan view of FIG. 8 viewed from above the HDOP axis. The movable region 50 is divided into regions I to IV by a line corresponding to the curve 58 in FIG. 8, that is, a line 581 obtained by projecting the curve 58 onto the coordinate plane. The positioning of the mobile station 10 in the area I is performed by the combination of the first base station 12A, the second base station 12B, and the fourth base station 12D, and the HDOP is minimized. The positioning of the mobile station 10 in the area II is HDOP is minimized by the combination of the first base station 12A, the second base station 12B, and the third base station 12C, and the positioning of the mobile station 10 in the region III is performed by the second base station 12B, the third base station 12C, The HDOP is minimized by the combination of the fourth base station 12D, and the positioning of the mobile station 10 in the region IV is performed by the combination of the first base station 12A, the third base station 12C, and the fourth base station 12D. It can be seen that is minimized. That is, as shown in FIG. 9, the position in the movable region 50 and the combination of the base station 12 with the smallest HDOP for performing the positioning of the mobile station 10 at the position are associated with each other, so that accurate positioning is possible. This makes it easy to select a base station for performing.

Returning to FIG. 4, the base station combination information holding unit 100 stores the combination of base stations 12 used by the position calculation unit 56 to calculate the position of the mobile station 10. For convenience, base station group numbers as shown in Table 1 below are assigned to combinations of base stations. Here, the base station set represents a combination of base stations.
[Table 1]
Base station group number Base station to be configured ―――――――――――――――――――――――――――――――――――
1 1st base station 12A 2nd base station 12B 3rd base station 12C
2 First base station 12A Second base station 12B Fourth base station 12D
3 1st base station 12A 3rd base station 12C 4th base station 12D
4 Second base station 12B Third base station 12C Fourth base station 12D

  The DOP map creation holding unit 102 calculates the HDOP when the position of the mobile station 10 at the center position of the cell 54 that divides the movable area 50 is calculated by a combination of predetermined base stations 12, and the calculated HDOP Are stored in a map or table form in association with the position of the cell 54 and the combination of the base stations 12. The positioning result output unit 60 outputs the positioning result, that is, the calculated position information of the mobile station 10 to, for example, a monitor device (not shown) or transmits it to another program. The center position of each cell 54 corresponds to a reference point.

  FIG. 10 shows the DOP when positioning is performed by the combination of the base station group number 1 for the mobile station 10 at the center of each cell 54 in the movable area 50, and the accuracy deterioration coefficient table It corresponds to. Similarly, FIG. 11 shows the DOP when the positioning is executed for the mobile station 10 at the center of each cell 54 of the movable area 50 by the combination of the base station group number 2. This is also executed for the combination of base station group numbers 3 and 4, and the obtained four maps are stored as DOP maps. That is, the DOP map is a collection of maps for one combination of base stations, corresponding to the number of combinations of base stations.

  Base station combination determining unit 104 corresponding to the optimum base station group determining step, the base station group collating step, and the selected base station group changing step or the optimum base station group determining unit, the base station group collating unit, and the selected base station group changing unit. Determines whether the combination of the base stations 12 used for the calculation of the position of the mobile station 10 by the position calculation unit 56 is appropriate, and determines which combination of the base stations 12 determines the mobile station It is determined whether 10 positions should be calculated. Specifically, the optimum base station group number representing the most suitable combination of base stations 12 for calculating the position of the mobile station 10 calculated by the position calculation unit 56 and the position calculation unit 56 actually The base station group number representing the combination of the base stations 12 used for calculating the position is compared. If they are the same, the combination of the mobile stations used by the position calculation unit 56 to calculate the position of the mobile station 10 is Judge that it was appropriate. On the other hand, if they are not the same, the position calculation unit 56 determines that the combination of the mobile stations used for calculating the position of the mobile station 10 is not appropriate, and the base station consisting of the combination corresponding to the optimal base station set number 12 is used to determine that the position of the mobile station 10 should be calculated. The details of the operation will be described later using a flowchart.

  The base station combination determination unit 104 includes an optimal base station group map creation unit 105. The optimum base station set map creation unit 105 creates an optimum base station set map based on the DOP map created by the DOP map creation holding unit 102. This optimal base station group map corresponds to the optimal base station group table. Then, the base station combination determination unit 104 executes these determinations based on the optimum base station group map created by the optimum base station group map creation unit 105. FIG. 12 is an example of the optimum base station set map, and is most suitable for positioning the mobile station 10 at the center of the cell 54 for each cell 54 in the movable area 50, that is, the DOP is the smallest. The base station group number is described.

  FIG. 13 is a flowchart showing an example of the control operation in the mobile station position estimation method of the present invention. In step (hereinafter, “step” is omitted) in FIG. 13, a map creation routine for creating the DOP map and the optimum base station set map shown in FIG. 14 is executed. In SA2, a positioning routine for accurate positioning shown in FIG. 15 is executed.

  FIG. 14 shows a map creation routine executed in SA1 of FIG. SB 1 to SB 6 correspond to the DOP map creation holding unit 102. In SB1, a combination of base stations is generated based on the total number of existing base stations 12 and the number of base stations that can be used for positioning. In SB2, the number of combinations of the base stations is stored in a variable NumPerm. In this embodiment, since positioning is to be performed using three base stations from a total of four base stations 12, a combination of four base stations is generated as shown in Table 1, and NumPerm = 4. In general, a combination in which the number of base stations is n and n to 3 base stations are selected is represented by nC3.

  In SB3, the variable i for iteration is initialized and i = 1. In SB4, for example, the mobile station 10 located at the center of all the cells 54 in the movable area 50 is positioned by the combination of the base stations described in the top of the table 1, that is, the base station set number is 1. In this case, the DOP (HDOP) is calculated, and the calculated DOP is associated with the position of each cell and stored as one map as shown in FIG.

  In SB5, it is determined whether SB4 has been executed for all base station groups. When it is executed for all base station groups, a collection of all the maps created in the previous SB4 is saved as a DOP map and the process proceeds to SB7, while it is executed for all base station groups. If not, 1 is added to the variable i indicating the number of times SB4 is executed in SB6, and SB4 is executed again.

  In SB 7 corresponding to the optimum base station set map creation unit 105, a base station set having the smallest DOP is searched for all the cells 54 in the movable area 50 based on the created DOP map, and the base station The set number is associated with the cell position and stored as an optimum base station map as shown in FIG. 12, for example. Specifically, a map having the smallest DOP is selected for a certain cell among all the maps constituting the DOP map, and the base station group number corresponding to the map is taken out.

  FIG. 15 is a positioning routine executed in SA2 of FIG. First, in SC1 corresponding to the base station combination information holding unit 100, a selected base station set which is an appropriate base station set is selected. For example, as shown in Table 1, a base station set number corresponding to the selected base station set is selected. Is stored in the variable c. At this time, the selection of the selected base station group is arbitrary. For example, when the base station group is listed as shown in Table 1, it may be the base station group described at the top, or in the optimum base station group map The base station set that is the optimum base station set in the most cells 54 may be used.

  In SC2 corresponding to the ranging unit 42 and the position calculating unit 56, ranging is performed using the base station 12 of the selected base station set selected in SC1, and each base station 12 and mobile station of the selected base station set are measured. Each distance from the mobile station 10 is measured, and calculation of the position of the mobile station 10, that is, positioning is executed based on the result of the distance measurement.

  Subsequent SC3 to SC5 correspond to the base station combination determination unit 104. First, in SC3, based on the optimal base station set map created in SA1, the base station set number of the optimal base station set corresponding to the position of the mobile station 10 calculated in SC2 is read. Specifically, the base station group number of the optimum base station group corresponding to the cell 54 including the position of the mobile station 10 calculated in SC2 is read.

  Subsequently, in SC4, the base station group number of the selected base station group used for positioning in SC2 is compared with the base station group number of the optimum base station group read in SC3 to determine whether or not they are the same. The If they are the same, the result of the positioning in SC2 is regarded as the most accurate, and the result of the positioning in SC2 is assumed to be the position of the mobile station 10, and this flowchart is ended. On the other hand, if they are not identical, SC5 is executed.

  In SC5, the optimum base station set read in SC3 is set as the selected base station set. Then, in SC6 corresponding to the distance measurement unit 42 and the position calculation unit 56, the distance measurement and positioning are performed again using the base station 12 newly selected as the selected base station group in SC5. The positioning result obtained as a result is assumed to be the position of the mobile station 10.

  According to the above-described embodiment, the optimum base station group map creation unit 105 performs the optimum base station group that is the base station group that minimizes the DOP that is the accuracy degradation coefficient for each position in the movable area 50 of the mobile station 10. Is determined and an optimum base station set map is created, and the base station combination determination unit 104 corresponds to the selected base station set used by the position calculation unit 56 and the position of the mobile station 10 calculated by the position calculation unit 56. It is determined whether or not the optimum base station set read from the map created by the optimum base station set map creating unit 105 matches, and the selected base station set and the optimum base station are determined in the judgment by the base station combination judging unit 104. When it is determined that the set does not match, the base station combination determination unit 104 determines that the selected base station set used in the position calculation unit 56 is the optimum base The selected base station set that has been changed to the set and changed by the base station combination determination unit 104 by the position calculation unit 56, that is, the optimum base station set corresponding to the position of the mobile station 10 calculated by the position calculation unit 56 is used. Since the position calculation of the mobile station 10 is performed again, the position of the mobile station 10 can be estimated with high accuracy.

  Further, according to the above-described embodiment, the optimum base station group map creation unit 105 stores the optimum base station group associated with the coordinates in the movable area 50 in the optimum base station group map as the optimum base station group table. Therefore, the base station combination determination unit 104 determines the optimum base station set corresponding to the mobile station position calculated by the position calculation unit 56 using the selected base station set by reading from the optimum base station set map. Rapid calculation is possible.

  Further, according to the above-described embodiment, the optimum base station set map creation unit 105 calculates all base station sets composed of a plurality of base stations, and sets a plurality of criteria set in advance in the movable area 50. At each of the centers of the cells 54 that are points, DOP that is an accuracy deterioration coefficient when the position of the mobile station 10 is calculated using one of the base station sets of the base station sets is calculated. A DOP map as an accuracy deterioration coefficient table for storing the DOP in association with the coordinates of the reference point is created for all the base station groups, and at each of the reference points, all the base station groups are created. Among the plurality of DOP maps created for the base station group, the base station group used when creating the DOP map having the smallest DOP at each reference point is associated with the coordinates of the reference point and the optimum base station group Since Save to-up, it is possible to create an optimal base station sets map representing the base station sets the DOP is minimized for each of the reference points.

  Further, according to the above-described embodiment, the optimum base station group map creation by the optimum base station group map creation unit 105 is performed for each cell 54 at a plurality of positions set in advance in the movable area 50 of the mobile station 10. Since the optimal base station set is determined in advance for a plurality of positions in the movable area 50, the position calculation unit 56 calculates the position of the mobile station 10 for the first time. The base station combination determination unit 104 determines an optimal base station set corresponding to the calculated position of the mobile station.

  Subsequently, another embodiment of the present invention will be described. In the following description, portions common to the embodiments are denoted by the same reference numerals and description thereof is omitted.

  FIG. 16 is another example of the positioning routine executed in SA2 of FIG. 13, and corresponds to FIG. SD1 to SD6 in FIG. 16 correspond to SC1 to SC6 in FIG. 15, respectively, and the operation in each step is common. The difference between FIG. 15 and FIG. 16 is as follows. That is, in FIG. 15, when the distance measurement and positioning are performed again in SC6, the flowchart ends with the result of the positioning as the position of the mobile station 10, whereas in FIG. In the same manner as described above, after the distance measurement and positioning are executed again, SD3 is executed again. Thus, in FIG. 16, when the base station group number of the selected base station group used for ranging and positioning matches the base station group number of the optimum base station group corresponding to the positioning result, The flowchart is terminated by assuming that the result of the positioning performed at the time is the position of the mobile station 10.

  According to the above-described embodiment, the position calculation unit 56 changes the selected base station set by the base station combination determination unit 104 used in the position calculation unit 56 and the position calculation unit using the changed other selected base station set. The calculation of the position of the mobile station again by 56 is repeatedly performed until the base station combination determination unit 104 determines that the selected base station set and the optimum base station set match. In this way, since the position of the mobile station 10 calculated by the position calculation unit 56 matches the optimum base station set corresponding to the position of the mobile station 10, the position of the mobile station 10 can be estimated with higher accuracy. It becomes possible.

  FIG. 17 shows step SE3 used in place of SC3 in the flowchart of FIG. 15 or SD3 in the flowchart of FIG. In the first and second embodiments described above, the flowcharts of FIGS. 15 and 16 are subroutines executed by SA2 of the flowchart of FIG. 13, but when SE3 is used in this embodiment, FIG. The flowchart of FIG. 16 is used alone, and it alone becomes a flowchart representing an example of the control operation in the mobile station position estimation method of the present invention. That is, FIG. 13 and FIG. 14 become unnecessary.

  Specifically, in the SE3 corresponding to the DOP map creation holding unit 102, the selection is performed with respect to the position determined to be the position of the mobile station 10 as a result of positioning based on the selected base station set in SC2 or SD2. The DOP is calculated by at least two or more base station sets including the base station set. Then, the base station set when the smallest DOP among the calculated DOPs is calculated is set as the optimum base station set.

  According to the embodiment described above, the determination of the optimum base station set by the base station combination determination unit 104 is calculated as the position of the mobile station 10 every time the position calculation unit 56 calculates the position of the mobile station 10. Therefore, it is not necessary to create an optimum base station set map by the optimum base station set map creation unit 105 in advance.

  FIG. 18 shows step SF3 used in place of SC3 in the flowchart of FIG. 15 or SD3 in the flowchart of FIG. 16, and corresponds to SE3 in FIG. In the above-described first and second embodiments, the flowcharts of FIGS. 15 and 16 are subroutines executed by SA2 of the flowchart of FIG. 13. However, when SF3 is used in this embodiment, the third embodiment is used. Similarly to the above case, the flowcharts of FIG. 15 and FIG. 16 are used alone, and only the flowcharts showing an example of the control operation in the mobile station position estimation method of the present invention. That is, FIG. 13 and FIG. 14 become unnecessary.

  Specifically, in SE3 corresponding to the DOP map creation holding unit 102, distance measurement is performed with respect to the position determined as the position of the mobile station 10 as a result of positioning based on the selected base station set in SC2 or SD2. The DOP is calculated by at least two or more base station sets including the selected base station set constituted by the possible base stations 12. Then, the base station set when the smallest DOP among the calculated DOPs is calculated is set as the optimum base station set. Here, the base station 12 capable of distance measurement means a base station that can be used for distance measurement. For example, whether or not the base station 12 has responded at the time of synchronization of the clock shown in FIG. Judgment is made based on whether or not any abnormality has occurred in the distance measurement performed. When there is a base station that cannot be used for distance measurement, the base station cannot be used for distance measurement and is not used as a base station constituting the base station group.

  According to the above-described embodiment, the optimum base station set determined by the base station combination determination unit 104 is configured by the base station 12 that can be used in the position calculation unit 56, and thus is the optimum base station set. It does not happen that the base station group cannot actually be used.

  FIG. 19 is another example of the flowchart of FIG. 15 or 16, and is a step used by being inserted into a portion surrounded by a broken line in FIG. 15 or FIG. 16. In step SG7, the base station group number of the base station group determined to be the optimum base station group for the positioning result using the selected base station group in SC3 or SD3 is stored, and the next time as shown in FIG. 15 or FIG. When selecting the selected base station set in SC1 or SD1 when the flowchart is executed, the base station set corresponding to the stored base station set number is set as the selected base station set.

  In the above description, SG7 has been described in the case where FIGS. 15 and 16 are used as the subroutine of FIG. 13 as in the first and second embodiments, but FIG. 15 or FIG. The same can be applied to the case of being used alone as shown in FIG. In this case, in SG7, the base station set number of the base station set determined as the optimal base station set in SE3 or SF3 as the base station set having the smallest DOP for the positioning result using the selected base station set And the base station set corresponding to the stored base station set number is selected when selecting the selected base station set in SE1 or SF1 when the flowchart of FIG. 15 or FIG. 16 is executed next time. A station group.

  According to the above-described embodiment, when the estimation of the position of the mobile station 10 is repeatedly performed by the mobile station position estimation method of the present invention or the position estimation apparatus of the present invention, the immediately preceding mobile station position estimation method or position estimation is performed. Since the optimum base station set used in the execution of the apparatus is used as the selected base station set in the position calculation unit 56, when the moving speed of the mobile station 10 is slow, the mobile station position estimation method of the present invention or When the position estimation device of the present invention is repeatedly executed, the selected base station set may be an optimal base station set at the time of repeated execution, so that it may not be necessary to execute position calculation again by the position calculation unit 56, The time required for position estimation can be shortened.

  FIG. 20 is an example of the flowchart of FIG. 15 or FIG. 16 when there are two or more mobile stations 10 in the movable region 50, and is inserted into the portion surrounded by the one-dot chain line in FIG. 15 or FIG. It is a step used. In this step SH0, mobile station numbers are assigned to the plurality of mobile stations 10, and mobile station numbers desired for positioning are selected. Then, SC1 or later or SD1 or later is executed for the mobile station selected by SH0.

In the above description, even if SH0 is used when FIG. 15 and FIG. 16 are used as the subroutine of FIG. 13 as in the first and second embodiments, FIG. 15 or FIG. It is possible to apply even when it is used alone as shown in FIG. In addition, when SG7 is provided at the bottom of the flowchart as in the fifth embodiment, the positioning result using the selected base station set in SC3 or SD3 at the previous execution for each mobile station as shown in Table 2 below. The base station group number of the base station group that is determined to be the optimum base station group is stored, and in the next execution SC1 or SD1, the selected base station number corresponding to the mobile station selected in SH0 is The selected base station may be selected by reading from Table 2.
[Table 2]
Mobile station number Selected base station group number for next execution ―――――――――――――――――――――――――――
1 1
2 4
3 4

  According to the above embodiment, when the mobile station is a plurality of mobile stations, the selection of the selected base station set and the determination of the optimum base station set are executed for each mobile station of the plurality of mobile stations. Even if there are a plurality of mobile stations 10, the position is calculated sequentially for each mobile station.

  When a part of the base station 12 fails, if the optimum base station set map including the failed base station is used as it is, the failed base station can be used even though it cannot actually be used due to failure. Since there are cases in which positioning cannot be performed, such as the necessity to perform positioning based on the optimal base station set including the above, it is necessary to prevent this.

  The failure determination unit 62 in FIG. 4 corresponds to a failure determination step or failure determination means, and when a part of a plurality of base stations fails, a normal base station excluding a part of the failed base stations performs a mobile station It is determined whether or not the position can be estimated.

  FIG. 21 is a flowchart for creating an optimal base station set map for enabling positioning even when a part of the base station 12 breaks down, and corresponds to FIG.

  First, in SJ1, a failure of some of the base stations 12 is detected. This failure is detected, for example, when communication with the base station 12 that has normally been in communication with the positioning server 14 has failed two times in succession, or when the base station 12 clearly detects erroneous distance measurement. This is performed based on the fact that data has been sent to the positioning server 14. In the subsequent SJ2, the number of base stations that have not failed among the base stations 12 is calculated, and it is determined whether the number of base stations that have not failed is sufficient for the minimum positioning. As described above, when the movable area 50 of the mobile station 10 is a plane, the number of base stations 12 required for the minimum positioning is three. It is determined whether this is the case. When this determination is affirmed, the subsequent SJ3 and subsequent steps are executed, whereas when this determination is negative, positioning cannot be executed and this flowchart is ended.

  In the subsequent SJ3, a combination of base stations is generated based on the number of base stations excluding the failed base station and the number of base stations that can be used for positioning. In SJ4, the number of combinations of the base stations is stored in a variable NumPerm. For example, when there are six base stations 12 in total and two of them are out of order, the four base stations 12 except for the base station that has failed are trying to perform positioning using three base stations. A combination of two base stations is generated and NumPerm = 4.

  Subsequent SJ5 to SJ9 correspond to SB3 to SB7 in FIG. 14, and the operation thereof is the same, so the description thereof is omitted. Since the optimum base station set map created in this way does not include the failed base station 12, it can be used by the positioning routine in FIG.

  According to the above-described embodiment, when a part of a plurality of base stations fails, it is determined whether or not the position of the mobile station can be estimated by a normal base station excluding a part of the failed base stations. If the failure determination unit 62 determines that the position of the mobile station can be estimated, the selection of the selected base station set and the determination of the optimum base station set are normal base stations. Therefore, the position of the mobile station 10 can be estimated even when some of the plurality of base stations fail.

  The present embodiment corresponds to a case where a part of the base station 12 has failed as in the seventh embodiment. FIG. 22 is a flowchart corresponding to the map creation routine of FIG. In FIG. 22, SK1 to SK6 correspond to SB1 to SB6 of FIG. 14, and the operation in each step is the same, so the description thereof is omitted. Subsequent SK7 to SK10 correspond to the optimum base station set map creation unit 105. In this flowchart, a multilayered optimum base station set map as shown in FIG. 23 is created. First, in SK7, the variable j for iteration is initialized to j = 1. This variable j is used to indicate the smallest DOP when the mobile station 10 located at the center of each cell 54 in the movable area 50 is positioned.

  In subsequent SK8, by searching the DOP map created by SK4 to SK6, the DOP when the mobile station 10 at the center of each cell 54 in the movable area 50 is located is the jth. The base station set is found and associated with the corresponding cell position, and stored in a map of the jth layer of the DOP map as shown in FIG. 23, for example. That is, at the first execution of SK8, a base station set that minimizes the DOP is found for each cell 54, and the base station set number corresponding to this base station set is associated with the position of the cell 54, for example, FIG. Are stored in the uppermost layer map of the multi-layered optimum base station set map shown in FIG.

  In SK9, it is determined whether SK8 is repeated by the number of all base station groups. If this determination is negative, j = j + 1 is set in SK10, and a search for a base station set with the next smallest DOP is performed for each cell 54. On the other hand, if the determination in this step is affirmative, the flowchart is terminated assuming that the multilayered optimum base station map has been created.

  The multi-layered optimum base station map created in this way is the base station set number of the base station set that reduces the DOP at the top layer for each cell 54 of the map, that is, the base station set number of the optimum base station set. In the next layer, the base station group number of the base station group that makes the DOP second smallest for each cell 54 is described, and the base station group number is described in order of decreasing DOP.

  FIGS. 24 and 25 are positioning routines corresponding to the case where FIG. 23 is used as a map creation routine, and correspond to FIGS. 15 and 16, respectively. 24 differs from FIG. 15 in that SL3 to SL6 are provided instead of SC3 in FIG. On the other hand, SL1, SL2, SL7, SL8, and SL9 correspond to SC1, SC2, SC4, SC5, and SC6, respectively, and the operation in each step is also the same, and thus the description thereof is omitted.

  In SL3, a variable i for iteration is initialized and i = 1. Subsequently, in SL4, among the multi-layered optimum base station map created in the flowchart of FIG. 23, the position corresponding to the position of the mobile station 10 determined based on the selected base station set in SL2 is corresponded. The base station set number described in the i-th layer map corresponding to the cell is read out. This is a candidate for the optimal base station set. That is, when SL4 is executed for the first time, in the uppermost layer map of the multi-layered optimum base station map, the position corresponding to the position of the mobile station 10 measured based on the selected base station set in SL2 is supported. The described base station set number corresponding to the cell to be read is read out.

  Subsequently, in SL5, it is determined whether or not the base station 12 constituting the optimal base station set candidate corresponding to the base station set number read in SL4 includes a failed base station. If this determination is affirmative, that is, if the optimal base station set candidate includes a failed base station, the variable i for repetition is set to i = i + 1 in SL6, and SL4 is executed again. Is done. As a result, when SL4 is executed again, the base station set that becomes the DOP smaller than the DOP at the previous execution is set as a candidate for the next optimum base station set. That is, at the time of the second execution of SL4 (i = 2), the base station set that makes the DOP second smallest for a certain cell 54 is determined as the optimum base station set candidate.

  On the other hand, FIG. 25 is compared with FIG. 16 in that SM3 to SM6 are provided instead of SD3 in FIG. On the other hand, SM1, SM2, SM7, SM8, and SM9 correspond to SD1, SD2, SD4, SD5, and SD6, respectively, and the operation in each step is also the same, and thus the description thereof is omitted. SM3 to SM6 operate in the same manner as SL3 to SL6 in FIG.

  According to the above-described embodiment, the base station combination determination unit 104 uses a plurality of combinations of the selected base station set for calculating the position of the mobile station 10 by the position calculation unit 56 using the selected base station set. Are ranked in ascending order of DOP as the accuracy degradation coefficient, and among the selected base station sets not including the part of the failed base stations 12, the one with the highest order is determined as the optimum base station set. Even when a part of the base station 12 fails, among the selected base station sets that do not include the failed base station, the one with the highest rank, that is, the one with the smallest DOP is set as the optimum base station set. Even when a part of the base station fails, it is possible to estimate the position with high accuracy.

  FIG. 26 is a functional block diagram illustrating an outline of the control function of the positioning server 14 used in this embodiment. In this figure, the boundary determination unit 106, the positioning error calculation unit 108, the allowable error calculation holding unit 112, and the like are additionally provided, and the base station combination determination unit 104 includes the boundary base station combination determination unit 110. It differs from FIG. 4 in having it. The allowable error calculation holding unit 112 calculates a positioning error e when the mobile station position estimation method of the present invention estimates the position of the mobile station 10, and holds the calculated value.

  The boundary determination unit 106 corresponding to the boundary determination step and the boundary determination unit includes a mask setting unit 114, a Lap value calculation unit 116, an edge processing unit 118, and the like, and the position of the mobile station 10 calculated by the position calculation unit 56 Is determined to be included in the boundary region in the optimum reference station group map created by the optimum reference station group map creation unit 105. Here, the boundary region includes an optimum reference station set corresponding to a cell 54 when attention is paid to a cell 54 in the optimum reference station set map, and an optimum reference station set corresponding to a cell 54 in the vicinity of the focused cell 54. An area that is different. Specifically, when the Lap value calculated by the Lap value calculation unit 116 is 0 with respect to the mask set by the mask setting unit 114, it is determined that there is no boundary region, and the Lap value is not 0. Is determined to be in the boundary region.

  When the position calculation unit 56 calculates the position of the mobile station 10, the mask setting unit 114 sets a mask centered on the cell 54 including the position. A method for setting the mask will be described. 27 to 29 are diagrams for explaining mask setting by the mask setting unit 114. The size and shape of the mask are determined based on the positioning error e calculated and held by the allowable error calculation holding unit 112. Specifically, for example, when the position of the mobile station 10 is calculated by the position calculation unit 56, when a circle with a radius e is drawn as the center of the cell 54 including the position, the smallest cell in which the circle is hidden is It is a mask. In the present embodiment, the movable area 50 is divided into square cells 54 each having a side of 1 m. Therefore, when the positioning error e is e <0.5 m, as shown in FIG. One cell including the position measured as is a mask. Further, when the positioning error e is 0.5 ≦ e <√2 / 2, as shown in FIG. 28, from the cell including the position measured as the position of the mobile station 10 and one cell above, below, left, and right A total of five cells become a mask. When the positioning error e is √2 / 2 ≦ e <1.5, as shown in FIG. 29, the cell including the position measured as the position of the mobile station 10 and the eight cells adjacent to the cell are included. A total of nine cells consisting of are masks. Similarly, when the positioning error e is 1.5 or more, the size and shape of the mask are determined.

The Lap value calculation unit 116 calculates the Lap value in the mask set by the mask setting unit 114. This Lap value is obtained by calculating an optimum base station group-related value, which is a value related to the optimum base station group associated with the cell included in the mask, using a predetermined equation. Specifically, for example, the optimum base station set related value is a value of a base station set number corresponding to the optimum base station set, and the predetermined formula is determined based on the following rule. That is,
(1) The optimum base station related values corresponding to the cells 54 other than the center of the mask are added together.
(2) Multiply the optimum base station related value corresponding to the cell 54 as the center of the mask by the number of cells 54 other than the center of the mask.
(3) The result of (2) is subtracted from the result of (1).
It is. The result of (3) is the Lap value. Specifically, in the example of FIG. 29, from the number obtained by adding the base station group numbers that are the optimum base station related values corresponding to the cells 54a to 54h, which are cells other than the center of the mask, at the center of the mask. It is calculated by subtracting the number obtained by subtracting 8, which is the number of cells 54a to 54h other than the center of the mask, from the base station number corresponding to a certain cell 54i. That is, in the example of the mask shown in FIGS. 27 to 29, the value described in the cell constituting the mask is the mask value, and the mask value is multiplied by the optimum base station related value corresponding to the cell. The combined value is added to all the cells so that the Lap value is obtained.

FIG. 30 shows a specific application of this to the optimum base station group map. Now, it is assumed that the positioning error e is √2 / 2 ≦ e <1.5, and the mask is set by nine cells including the position measured as the position of the mobile station 10, as shown in FIG. When the position of the mobile station 10 calculated by the position calculation unit 56 is included in the cell 54j, the mask is calculated as indicated by a thick line Rj in FIG. And the Lap value at this time is
4 + 4 + 4 + 4 + 4 + 4 + 4 + 4-4 × 8 = 0
Therefore, in this case, the boundary determination unit 106 determines that the cell 54j is not in the boundary region. On the other hand, when the position of the mobile station 10 calculated by the position calculation unit 56 is included in the cell 54k, the mask is calculated as indicated by a thick broken line Rk in FIG. And the Lap value at this time is
4 + 5 + 3 + 5 + 3 + 5 + 5 + 3-5 × 8 = −7
Since the Lap value is not 0, the boundary determining unit 106 determines that the cell 54k is in the boundary region.

  By the way, when the position calculated by the position calculation unit 56 and the position calculated by the position calculation unit 56 are the end of the movable region 50, the mask set by the mask setting unit 114 corresponds to the movable region 50. In some cases, the optimal base station group map created in this way straddles the inside and the outside. For example, as shown in FIG. In FIG. 31, the position calculated by the position calculation unit 56 and the position calculated by the mobile station 10 are included in the cell 54m shown in FIG. 31. At this time, the mask is calculated as indicated by the thick line Rm, And straddles the outside. In such a case, since the Lap value cannot be calculated by the Lap value calculation unit 116 as it is, the edge processing unit 118 performs a process of changing the mask value corresponding to the cells constituting the mask.

Specifically, the edge processing unit 118 sets the mask value corresponding to the cell existing outside the optimum base station set map to 0 among the cells constituting the mask, and sets the mask value to the cell 54 serving as the center of the mask. The mask value is changed so that the corresponding mask value is obtained by multiplying the number of cells 54 existing inside the optimal base station map among the cells 54 other than the center of the mask by -1. For example, the mask value of the mask represented by the thick line Rm in the case of FIG. 31 is represented as shown in FIG. Since the mask value is changed by the edge processing unit 118 as described above, the Lap value is calculated by the Lap value calculation unit 116 as follows.
(1 ′) Among the cells 54 other than the center of the mask, the optimum base station related values corresponding to the cells 54 existing inside the optimum base station set map are added together.
(2 ′) The optimum base station related value corresponding to the cell 54 serving as the center of the mask is multiplied by the number of cells 54 existing in the optimum base station set map among the cells 54 other than the center of the mask.
(3 ′) The result of (2 ′) is subtracted from the result of (1 ′).
It is. The result of (3 ′) is the Lap value. Specifically, the Lap value of the mask calculated as shown by the thick line Rm in FIG.
0 + 0 + 0 + 0 + 4 + 0 + 4 + 4-4 × 3 = 0
Therefore, in this case, the boundary determination unit 106 determines that the cell 54m is not in the boundary region.

  The positioning error calculation unit 108 performs masking in the optimum base station set map when the boundary determination unit 106 determines that the position determined to be the position of the mobile station 10 calculated by the position calculation unit 56 is in the boundary region. The position calculation unit 56 performs the calculation of the position of the mobile station 10, that is, the positioning, a predetermined number of times using all the base station sets corresponding to the cells 54 included in the mask set by the setting unit 114, and each base station Calculate the positioning error when using a set. Here, the positioning error is, for example, a standard deviation, and the predetermined number of times is determined as a number of times greater than or equal to the number of times that the standard deviation can be calculated.

  The boundary-time positioning result calculation unit 110 corresponding to the boundary-neighboring mobile station position calculating step or the boundary-neighboring mobile station position calculating unit is configured so that the position determined to be the position of the mobile station 10 calculated by the position calculating unit 56 When it is determined by 106 that the current position is in the boundary region, the base station set when the positioning error is the smallest among the positioning errors calculated by the positioning error calculation unit 108 is selected. Then, the calculation of the position of the mobile station 10 is executed again using the selected base station group, and this result is set as the position of the mobile station 10.

  Specifically, for example, if the mask is calculated as indicated by a thick broken line Rk in FIG. 30, the positioning error calculation unit 108 uses the base station described in the cell of the optimal base station set map corresponding to the mask cell. Positioning of the mobile station 10 by the position calculation unit 56 is executed a predetermined number of times using the base station groups of the numbers 3, 4 and 5, which are numbers, and positioning errors are calculated respectively. The boundary-time base station combination determining unit 110 then determines the positioning error with the smallest positioning error when using the base station set corresponding to the base station set number 3 among the positioning errors corresponding to these three base station sets. If so, the base station group corresponding to the base station group number 3 is selected. Then, the position of the mobile station 10 is calculated again using the base station group corresponding to the base station group number 3, and this result is used as the position of the mobile station 10.

  FIG. 33 is a part of a positioning routine considering whether the position of the mobile station 10 that has been positioned is a boundary, between SC2 and SC3 in FIG. 15 or between SD2 and SD3 in FIG. It is executed by inserting it into the portion of the two-dot chain line described in 1.

  First, in SN1 corresponding to the boundary determination unit 106, the boundary determination routine of FIG. 34 is executed. The flowchart in FIG. 34 explains this boundary determination routine. First, in SP1 corresponding to the mask setting unit 114, a cell including the position that is assumed to be the position of the mobile station 10 calculated in SC2 or SD2 is displayed. The center mask is set. At this time, when the mask is set across the outside of the optimum base station set map, the mask value correction processing by the edge processing unit 118 described above is executed.

  In SP2 corresponding to the Lap value calculation unit 116, the Lap value corresponding to the mask set in SP1 is calculated.

  Returning to FIG. 33, in SN2, the position of the mobile station 10 measured in SC2 or SD2 is in the boundary region based on whether or not the Lap value, which is the result of execution of the boundary determination routine in SN1, is 0. It is determined whether or not. When this determination is affirmative, that is, when the Lap value is 0 and the position that is assumed to be the position of the mobile station 10 calculated in SC2 or SD2 is in the boundary region, the case of FIG. 15 or FIG. SN3 and subsequent steps are executed on the assumption that different processing is required. On the other hand, when this determination is negative, that is, when the Lap value is 0 and the position determined to be the position of the mobile station 10 calculated in SC2 or SD2 is not in the boundary region, FIG. 15 or FIG. Steps SC3 and subsequent steps or SD3 and subsequent steps are subsequently executed.

  SN3 and SN4 correspond to the positioning error calculator 108. First, in SN3, positioning of the mobile station 10 is executed using a plurality of base station groups corresponding to the base station group number in the optimum base station group map corresponding to the mask set in SP1. This positioning is executed a predetermined number of times for each base station group. This predetermined number of times is a number of times sufficient for the positioning error calculated in the subsequent SN4 to have sufficient reliability, and is determined in consideration of the time required for calculation and the time required for distance measurement.

  In SN4, the positioning error in the positioning of the mobile station 10 executed in SN3 is calculated for each mobile station group. This positioning error is a standard deviation, for example. In this case, the predetermined number of times in SN3 is the number of times that a positioning result sufficient to calculate this standard deviation is obtained, for example, 10 times.

  In SN5 corresponding to the boundary-time positioning result calculation unit 110, the base station set when the positioning error is the smallest among the positioning errors calculated for the plurality of base station sets in SN4 is selected, and the selected base The positioning of the mobile station 10 is executed again using the station group, and this flowchart is ended assuming that the result is the position of the mobile station 10.

  According to the above-described embodiment, the optimal base station set in which the position of the mobile station 10 calculated by the position calculation unit 56 is determined by the base station combination determination unit 104 with respect to the position of the mobile station 10, and the mobile station 10 A boundary determination unit 106 that determines whether or not the optimum base station set determined by the base station combination determination unit 104 is in a different boundary region with respect to the vicinity of the position of the mobile station, and the boundary determination unit 106 When it is determined that the position of 10 is in the boundary area, it has a boundary-time positioning result calculation unit 110 that calculates the position of the mobile station in consideration of the optimum base station set in the boundary area. Even when the position of the mobile station 10 calculated by the calculation unit 56 is in the boundary region, the optimum base station set can be determined.

  Further, according to the above-described embodiment, the optimum base station set map creation unit 105 sets the base station as the optimum base station set related value related to the optimum base station set for each optimum base station set in the optimum base station set map. The boundary determination unit 106 assigns a set number, and the boundary determination unit 106 includes the optimal base station corresponding to the mobile station position calculated by the position calculation unit 56 and the optimal base station set determined by the Lap value calculation unit 116 in the vicinity. Since it is determined whether or not the mobile station position is at a boundary based on a Lap value that is a weighted average of station group related values, the optimal base station corresponding to a plurality of optimal base station groups existing in the boundary region It is determined whether or not the mobile station position is at the boundary based on a Lap value that is a weighted average of the pair-related values.

  Further, according to the above-described embodiment, the mask setting unit 114 generates the size of the mask as the boundary region according to the specifications of the mobile station 10, the plurality of base stations 12, and the mobile station position estimation method. Since the determination is made based on the error e occurring at the time of 10 positioning, the boundary region can be determined in consideration of the error.

  Further, according to the above-described embodiment, the edge processing unit 118 is configured such that the mask as the boundary region exists across both the inside of the movable region 50 and the outside of the movable region 50. Since the weighting is performed without considering the optimum base station set-related value outside the movable area 50, the boundary determination unit 106 determines whether the mask as the boundary area is between the inside of the movable area 50 and the outside of the movable area 50. Even when it exists over both, the position measurement result calculation unit 110 at the boundary can estimate the position of the mobile station 10.

  As mentioned above, although the Example of this invention was described in detail based on drawing, this invention is applied also in another aspect.

  For example, in the above-described embodiment, the movable area 50, which is an area in which the mobile station 10 can move, is provided as a square plane having a side of 30m, but is not limited thereto. Specifically, the shape is not limited when the movable region 50 is a plane, and the movable region 50 may be provided as a space instead of a plane, and the shape in that case is not limited. If the movable area 50 is provided as a space, the number of base stations necessary for positioning is at least four as described above.

  In the above-described embodiment, the positioning server 14 and each base station 12 are connected by the wired cable 52 to perform communication. However, the communication between the positioning server 14 and each base station 12 is not limited to wired communication. For example, it is possible by radio waves or infrared rays.

  In the above-described embodiment, the balance / unbalance conversion unit 22 provided in the mobile station 10 and the base station 12 is not always necessary, and may have only a function as a matching unit depending on the configuration state of the device. .

  In the above-described embodiment, the direct spreading method is adopted as the method of the spectrum spreading unit 34, but the present invention is not limited to this, and other methods such as UWB (Ultra Wide Band) may be used.

  In the above-described embodiment, the position calculation unit 56 solves the above equation (1) as a simultaneous equation using the Newton-Raphson method or the like, but is not limited to this. An optimal solution may be derived based on this.

  In the above-described embodiment, the distance measuring unit 40 is provided as a function of the base station 12, but is not limited thereto, and may be provided in the positioning server 14, for example. In this case, for example, the signal wave received by the base station 12 may be transmitted from the base station 12 to the positioning server 14 as it is.

  In the first embodiment, the positioning routine is executed after the map creation routine is executed. However, the present invention is not limited to this. For example, these routines may be executed in parallel at the same time. Also good.

  In the above-described embodiment, once the optimum base station group map is created, the created optimum base station group map is used as it is. However, the present invention is not limited to this. For example, the following positioning, etc. It may be learned or updated based on

  In the ninth embodiment, the boundary positioning result calculation unit 110 determines that the position determined to be the position of the mobile station 10 calculated by the position calculation unit 56 is in the boundary region by the boundary determination unit 106. In this case, the base station set in the case where the positioning error is the smallest among the positioning errors calculated by the positioning error calculation unit 108 is selected, and the position of the mobile station 10 is again determined using the selected base station set. For example, when the selected base station set matches the base station set when the position of the mobile station 10 is calculated by the position calculation unit 56, the position calculation is not necessarily performed again. Is not necessary.

  In the above-described embodiment, an example of performing positioning using three of the four base stations 12 is shown, but this is only an example, and the total number of existing base stations is shown. The base station used for positioning may be any base station that is at least as many as the required number of base stations.

  In the above-described embodiment, the base station combination determining unit 104 serving as the optimal base station group determining step or the optimal base station group determining unit determines the base station group having the smallest HDOP as the accuracy degradation coefficient as the optimal base station Although it was decided to be a group, it is not limited to this. For example, the base station group having the accuracy degradation coefficient smaller than a predetermined value may be determined as the optimum base station. In this way, since the base station set having the accuracy degradation coefficient smaller than the predetermined value is determined as the optimum base station, the optimum base station set can be obtained without calculating and comparing the accuracy degradation coefficients for all the base station groups. The time required for the optimum base station set can be shortened.

  In the above-described embodiment, the optimal base station set determined by the base station combination determining unit 104 as the optimal base station set determining step or the optimal base station set determining means has the smallest HDOP as the accuracy degradation coefficient. The base station set checking step or the base station set checking means determines whether or not the selected base station set matches the optimum base station set. Not limited. For example, as described above, the base station set whose accuracy degradation coefficient is smaller than a predetermined value is determined as the optimal base station by the optimal base station set determining step or the optimal base station set determining means. In some cases, a plurality of base station sets may be set as the optimum base station set, and the base station set checking step or the base station set checking means configures the selected base station set and the optimum base station set. It may be determined whether or not any of a plurality of base station sets matches, that is, whether or not the selected base station set is included in a plurality of base station sets constituting the optimum base station set. In this way, even if a plurality of base station sets are determined as the optimum base station, any of the bases in which the selected base station set constitutes the optimum base station set composed of the plurality of base station sets. Since it is determined whether or not it matches the station set, when there are a plurality of base station sets included in the predetermined range including the minimum value of the accuracy degradation coefficient, the plurality of base station sets are The number of times that the selected base station is changed in the selected base station changing step and the position of the mobile station is calculated again in the mobile station position calculating step is reduced, and the position of the mobile station is calculated. Is shortened.

  In the above-described embodiment, the base station combination determining unit 104 as the optimal base station determination step or the optimal base station determination means determines one optimal base station group for each cell 54. I can't. For example, in the mobile station position calculating step or the mobile station position calculating means, the optimum base station is set according to the frequency of the radio wave used for calculating the position of the mobile station by being transmitted by the mobile station and received by the base station. It may be determined. In this way, when the mobile station is used to calculate the position of the mobile station by being transmitted by the mobile station and received by the base station in the mobile station position calculation step or the mobile station position calculation means, a plurality of frequencies differ. When radio waves are switched and used, even if the influence of multipath changes depending on the frequency of the radio waves and the optimum base station set changes, the optimum base station is determined in consideration of this. Is called. Further, the optimum base station set is determined in advance for the radio waves having different frequencies, and stored for each radio wave of each frequency, that is, as shown in FIG. 12 for each radio wave of each frequency. You may make it preserve | save an optimal base station group map.

It is a figure showing an outline of an example of a positioning system to which the present invention is applied. It is a figure explaining a mode that a movable area is divided by a cell. It is a functional block diagram showing the outline | summary of the function of a mobile station and a base station. It is a functional block diagram showing the outline | summary of the function of the positioning server. It is a figure for demonstrating the principle of the positioning by a positioning server. It is a time chart explaining an example of the procedure which synchronizes the clock which a base station has. It is a time chart explaining an example of the procedure which measures the distance of each base station and a mobile station. It is a figure explaining a mode that the base station group which gives the minimum DOP by a area | region differs in a movable area | region. It is a figure showing a mode that the movable area was divided according to the base station group which gives the minimum DOP, Comprising: It is the figure which projected FIG. 8 to the movable area. It is a figure showing the example of the 1st sheet of a DOP map. It is a figure showing the 2nd example of a DOP map. It is a figure showing an example of the optimal base station group map. 5 is a flowchart for calculating a position of a mobile station in the present invention. It is a flowchart explaining the map creation routine for creation of the optimal base station group map in FIG. It is a flowchart explaining the positioning routine for the calculation with a sufficient precision of the position of the mobile station in FIG. FIG. 16 is a diagram for explaining a positioning routine according to another embodiment of the present invention, corresponding to FIG. 15. It is a figure explaining the positioning routine by another Example of this invention, Comprising: It is a step performed instead of a part of FIG. 15 or FIG. It is a figure explaining the positioning routine by another Example of this invention, Comprising: It is a step performed instead of a part of FIG. 15 or FIG. It is a figure explaining the positioning routine by another Example of this invention, Comprising: It is a step performed in addition to FIG. 15 or FIG. It is a figure explaining the positioning routine by another Example of this invention, Comprising: It is a step performed in addition to FIG. 15 or FIG. FIG. 15 is a diagram for explaining a map creation routine corresponding to a case where a part of a base station fails, which is another embodiment of the present invention, corresponding to FIG. 14. FIG. 15 is a diagram for explaining a map creation routine corresponding to a case where a part of a base station fails, which is another embodiment of the present invention, corresponding to FIG. 14. The multi-layered optimum base station set map created when FIG. 22 which is a map creation routine corresponding to a case where a part of the base station has failed, according to another embodiment of the present invention will be described. FIG. 13 is a diagram corresponding to FIG. 12. FIG. 16 is a diagram for explaining a positioning routine corresponding to a case where a part of a base station fails, which is another embodiment of the present invention, corresponding to FIG. 15. FIG. 17 is a diagram for explaining a positioning routine corresponding to a case where a part of a base station has failed according to another embodiment of the present invention, corresponding to FIG. 16. It is a functional block diagram explaining the outline | summary of the function of the positioning server in another Example of this invention. It is the figure which showed the relationship between the error in positioning, and the magnitude | size of a mask. It is the figure which showed the relationship between the error in positioning, and the magnitude | size of a mask. It is the figure which showed the relationship between the error in positioning, and the magnitude | size of a mask. It is a figure explaining a mode that a mask process is performed to the optimal base station group map. It is a figure explaining a mode that a mask is set ranging over the exterior of the optimal base station group map. It is a figure explaining a mode that a mask is set ranging over the exterior of the optimal base station group map. It is a figure explaining the positioning routine in case a mask is set over the exterior of an optimal base station group map, Comprising: It is a step performed in addition to FIG. 15 or FIG. It is a figure explaining the boundary determination routine in the positioning routine of FIG.

Explanation of symbols

10: mobile station 12: base station 14: positioning server 56: position calculation unit (mobile station position calculating step, mobile station position calculating means)
60: Positioning result output unit 62: Failure determination unit (failure determination step, failure determination means)
100: base station combination information holding unit 102: DOP map creation holding unit 104: base station combination determining unit (optimum base station group determining step, base station group checking step, selected base station group changing step, optimal base station group determining means, Base station set verification means, selected base station set change means)
105: Optimal base station set map creation unit 106: Boundary determination unit (boundary determination step, boundary determination means)
108: Positioning error calculation unit 110: Boundary positioning result calculation unit (border vicinity mobile station position calculation step, boundary vicinity mobile station position calculation means)
112: Allowable error holding unit 114: Mask setting unit 116: Lap value calculation unit 118: Edge processing unit

Claims (30)

A radio wave transmitted from a mobile station moving in a predetermined movable area is received by a base station set consisting of a combination of a plurality of base stations installed in advance at a predetermined position, and based on the radio wave received by the base station set A mobile station position calculating step for calculating the position of the mobile station, and a minimum number of the base stations constituting the base station set necessary for calculating the position of the mobile station in the mobile station position calculating step A mobile station location estimation method when there are more base stations than
Corresponding to the position of the mobile station in the movable region, an accuracy deterioration coefficient that is a coefficient representing deterioration in accuracy when used for calculating the position of the mobile station from the plurality of base stations in the mobile station position calculation step is An optimal base station set determining step for determining an optimal base station set which is the base station set to be minimized; and
When the position of a predetermined mobile station is calculated by the mobile station position calculating step using a selected base station set that is one base station set selected from the base station set, the mobile station position calculating step uses the It is determined whether or not the selected base station set matches the optimum base station set determined by the optimum base station set determining step corresponding to the position of the mobile station calculated by the mobile station position calculating step. A base station group verification process,
When it is determined in the collation by the base station group collation step that the selected base station group and the optimum base station group do not match, the selected base station group used in the mobile station position calculating step is determined as the optimum base station A selected base station group changing step for changing to a station group,
The mobile station position calculating step includes performing the mobile station position calculation again using the selected base station group changed by the selected base station group changing step. 2. The mobile station position estimation method according to claim 1, wherein the optimal base station set determination step stores the optimal base station set associated with coordinates in the movable area in an optimal base station set table. . The optimal base station set determination step includes:
Calculate all base station sets composed of the plurality of base stations,
The accuracy degradation when the position of the mobile station is calculated using one base station set of all the base station sets at each of a plurality of preset reference points in the movable region A coefficient is calculated, and an accuracy deterioration coefficient table for storing the accuracy deterioration coefficient in association with the coordinates of the reference point is created for all the base station groups, and
In each of the reference points, among the plurality of accuracy degradation coefficient tables created for all the base station groups, it is used when creating the accuracy degradation coefficient table with the smallest accuracy degradation coefficient at the reference point. The mobile station position estimation method according to claim 2, wherein the base station group stored is stored in the optimum base station group table in association with the coordinates of the reference point. Change of the selected base station set used in the mobile station position calculating step by the selected base station set changing step and re-positioning of the mobile station by the mobile station position calculating step using another changed selected base station set The calculation of is performed repeatedly until it is determined that the selected base station set and the optimum base station set match in the base station set collating step. The mobile station position estimation method described in 1. The determination of the optimal base station group in the optimal base station group determination step is executed in advance for a plurality of positions set in advance in the movable area of the mobile station. The mobile station position estimation method according to claim 1. The determination of the optimal base station group by the optimal base station group determination step is executed for the part calculated as the position of the mobile station every time the position of the mobile station is calculated by the mobile station position calculation step. The mobile station position estimation method according to claim 1, wherein the mobile station position is estimated. The optimal base station group determined by the optimal base station group determining step is configured by the base station that can be used in the mobile station position calculating step. The mobile station position estimation method described. When the estimation of the position of the mobile station by the mobile station position estimation method is repeatedly executed, the base station collation step uses the optimum base station set used for the previous estimation as the selected base station set. The mobile station position estimation method according to any one of claims 1 to 7. The mobile station is a plurality of mobile stations, and the selection of the selected base station set and the determination of the optimum base station set are executed for each mobile station of the plurality of mobile stations. The mobile station position estimation method according to any one of 1 to 8. In the case where a part of the plurality of base stations fails, it has a failure determination step of determining whether or not the mobile station can be estimated by normal base stations excluding the part of the base stations that have failed.
When it is determined that the mobile station can be estimated by the failure determination step, the selection of the selected base station set and the determination of the optimum base station set are performed from the normal base station. The mobile station position estimation method according to any one of claims 1 to 9. The optimum base station set determination step uses a plurality of combinations of the selected base station sets when calculating the position of the mobile station by the mobile station position calculation step using the selected base station set. 11. The system according to claim 10, wherein the base stations are ranked in ascending order, and the selected base station set not including some of the failed base stations is determined as the optimum base station set from among the selected base station sets. Mobile station position estimation method. The position of the mobile station calculated by the mobile station position calculating step is determined by the optimal base station set determining step with respect to the position of the mobile station, and the vicinity of the position of the mobile station A boundary determination step for determining whether or not the optimal base station set determined by the optimal base station set determination step is in a different boundary region;
When the boundary determination step determines that the position of the mobile station is in the boundary area, a mobile station position in the vicinity of the boundary that calculates the position of the mobile station in consideration of the optimum base station set in the boundary area The mobile station position estimation method according to claim 1, further comprising: a calculation step. The optimal base station set determination step attaches an optimal base station set related value related to the optimal base station set for each determined optimal base station set,
The boundary determination step is based on a weighted average of the optimum base station set related values corresponding to the optimum base station set determined by the optimum base station set decision step in the determined mobile station position and the vicinity. The mobile station position estimation method according to claim 12, wherein it is determined whether or not the mobile station position is at a boundary. In the boundary determination step, the size of the boundary region is determined based on an error that occurs during positioning of the mobile station, which occurs due to specifications of the mobile station, the plurality of base stations, and the mobile station position estimation method. The mobile station position estimation method according to claim 12, wherein the mobile station position is estimated. In the boundary determination step, when the boundary area exists across both the inside of the movable area and the outside of the movable area, the optimum base station set related value outside the movable area The mobile station position estimation method according to claim 13, wherein weighting is performed without considering A radio wave transmitted from a mobile station moving in a predetermined movable area is received by a base station set consisting of a combination of a plurality of base stations installed in advance at a predetermined position, and based on the radio wave received by the base station set Mobile station position calculating means for calculating the position of the mobile station, and the minimum number of the base stations constituting the base station set necessary for calculating the position of the mobile station in the mobile station position calculating means A mobile station location estimation apparatus when there are more base stations than
Corresponding to the position of the mobile station in the movable region, an accuracy deterioration coefficient that is a coefficient representing deterioration in accuracy when used for calculating the position of the mobile station by the mobile station position calculating means from the plurality of base stations. An optimum base station set determining means for determining an optimum base station set that is the base station set that is minimized;
When the position of a predetermined mobile station is calculated by the mobile station position calculating means using a selected base station set that is one base station set selected from the base station set, the mobile station position calculating means uses the It is determined whether or not the selected base station set matches the optimal base station set determined by the optimal base station set determining means corresponding to the position of the mobile station calculated by the mobile station position calculating means. Base station group verification means for
In the collation by the base station group collating unit, if it is determined that the selected base station group and the optimum base station group do not match, the selected base station group used in the mobile station position calculating unit is determined as the optimum base station group. A selection base station group changing means for changing to a station group;
The mobile station position estimation means performs the mobile station position calculation again using the selected base station set changed by the selected base station set change means. The mobile station position according to claim 16, wherein the optimal base station set determining means stores the optimal base station set positioned using coordinates in the movable area in an optimal base station set table. Estimating device. The optimum base station set determining means includes:
Calculate all base station sets composed of the plurality of base stations,
The accuracy degradation when the position of the mobile station is calculated using one base station set of all the base station sets at each of a plurality of preset reference points in the movable region A coefficient is calculated, and an accuracy deterioration coefficient table for storing the accuracy deterioration coefficient in association with the coordinates of the reference point is created for all the base station groups, and
In each of the reference points, among the plurality of accuracy degradation coefficient tables created for all the base station groups, it is used when creating the accuracy degradation coefficient table with the smallest accuracy degradation coefficient at the reference point. The position estimation apparatus according to claim 17, wherein the base station group stored is stored in the optimum base station group table in association with the coordinates of the reference point. The change of the selected base station set used in the mobile station position calculating means by the selected base station set changing means, and the position of the mobile station again by the mobile station position calculating means using another changed selected base station set 19. The calculation of is repeatedly performed until it is determined by the base station set collating means that the selected base station set and the optimum base station set match each other. The position estimation apparatus described in 1. The optimal base station set determination by the optimal base station set determination means is executed in advance for a plurality of positions set in advance within the movable area of the mobile station. A position estimation device according to claim 1. The determination of the optimal base station set by the optimal base station set determining means is executed for the portion calculated as the position of the mobile station every time the position of the mobile station is calculated by the mobile station position calculating means. The position estimation device according to any one of claims 16 to 20, wherein The optimal base station group determined by the optimal base station group determining unit is configured by the base station that can be used in the mobile station position calculating unit. The position estimation apparatus described. The base station collating means uses the optimum base station set used for the previous estimation as the selected base station set when the position estimation of the mobile station by the position estimation device is repeatedly executed. Item 23. The position estimation device according to any one of Items 16 to 22. The mobile station is a plurality of mobile stations, and the selection of the selected base station set and the determination of the optimum base station set are executed for each mobile station of the plurality of mobile stations. The position estimation apparatus according to any one of 16 to 23. In the case where a part of the plurality of base stations fails, it has a failure determination means for determining whether or not a mobile station can be estimated by a normal base station excluding the part of the base stations that have failed.
When it is determined that the mobile station can be estimated by the failure determination means, the selection of the selected base station set and the determination of the optimum base station set are performed from the normal base station. The position estimation apparatus according to any one of claims 16 to 24. The optimum base station set determining means uses a plurality of combinations of the selected base station sets when calculating the position of the mobile station by the mobile station position calculating means using the selected base station set. 26. The system is ranked in ascending order and the selected base station set not including some of the failed base stations is determined as the optimal base station set in the selected base station set. Position estimation device. The position of the mobile station calculated by the mobile station position calculating means is determined by the optimal base station set determining means with respect to the position of the mobile station, and the vicinity of the position of the mobile station Boundary determining means for determining whether or not the optimal base station set determined by the optimal base station set determining means is in a different boundary region;
When the boundary determination unit determines that the position of the mobile station is in the boundary area, the mobile station position near the boundary calculates the position of the mobile station in consideration of the optimum base station set in the boundary area 27. The position estimation device according to claim 16, further comprising a calculation unit. The optimum base station set determining means attaches an optimum base station set related value related to the optimum base station set to each determined optimum base station set,
The boundary determination means is based on the weighted average of the optimum base station set related values corresponding to the optimum base station set determined by the optimum base station set decision means in the determined mobile station position and the vicinity. The position estimation apparatus according to claim 27, wherein it is determined whether or not the mobile station position is at a boundary. The boundary determination means determines the size of the boundary region based on an error that occurs during positioning of the mobile station, which occurs due to specifications of the mobile station, the plurality of base stations, and the position estimation device. 29. The position estimation apparatus according to claim 27, wherein the position estimation apparatus is characterized in that: The boundary determination means, when the boundary region exists across both the inside of the movable region and the outside of the movable region, the optimum base station set related value outside the movable region 30. The position estimation apparatus according to claim 28, wherein weighting is performed without considering

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