JP5345423B2 - Positioning system and positioning method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To diminish an error in computation of the location of a mobile terminal and to accurately calculate the location of the mobile terminal even when a base station of multipath reception exists. <P>SOLUTION: A computer 10 of this positioning system receives reception time information which is the information regarding the reception time when each base station receives a radio wave from the mobile terminal, and computes the location of the mobile terminal by using the received reception time information. The computer 10 computes the backward reception time backward by using the location of the mobile terminal and the location information on each base station, and evaluates each base station by using a difference between the received reception time information and the backward reception time obtained by backward computation. Using the result of evaluation of each evaluated base station, in succession, the computer 10 selects the base station to be used for computation of the location of the mobile terminal, out of the individual base stations, and computes the location of the mobile terminal by using the information on the reception time of the selected base station. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a positioning system and a positioning method for calculating the position of a mobile terminal from radio wave propagation time differences at a plurality of base stations.

  One method for measuring the position of a mobile terminal is a TDOA (Time Difference Of Arrival) method. This method is a method for calculating the position of a mobile terminal from the propagation time differences of radio waves at a plurality of base stations whose positions are known. FIG. 12 is a diagram illustrating an example of a wireless positioning system that performs positioning based on a propagation time difference.

  As shown in FIG. 12, this positioning system has a mobile terminal, a plurality of base stations, and a computer, and each base station and the computer are connected by a communication cable. Here, in this positioning system, the coordinates of the base station are assumed to be accurately known in advance.

  Each base station receives a positioning pulse transmitted from a mobile terminal (for example, a small tag), measures a reception time, and transmits information on the measured reception time (hereinafter, reception time information) to a computer. The computer is a device that calculates the position of the mobile terminal based on all reception time information transmitted from each base station. For example, the computer calculates the propagation time difference between the base stations using the reception time times received from all the base stations, and performs position calculation based on the propagation time difference and the base station coordinates.

  As a positioning method in a mobile communication system employing a CDMA system, a plurality of combinations of base stations that do not include the same PN offset value are determined, an error function is evaluated, and the one that minimizes the error function is selected. The technique of doing is known (refer patent document 1, 2). The positioning method of the mobile communication system adopting the CDMA system described above is based on the technology of the TDOA positioning system handled in the present invention, in which the base station is the transmitting side and the mobile terminal that performs positioning is the receiving side. The transmission and reception directions are reversed.

JP 2003-37862 A JP-A-7-181242

  By the way, the above-described positioning system technology is based on the premise that the radio wave propagation path from the mobile terminal to the base station is the shortest straight line. The relationship between the mobile terminal (tag) and the base station A will be described using the example of FIG. On the other hand, in an actual usage environment, there may be a base station that receives light (multipath reception) by reflection / diffraction due to the influence of a shield or the like. Explaining using the example of FIG. 13, the relationship between the mobile terminal (tag) and the base station B is shown.

  For this reason, in the positioning system technique described above, the position of the mobile terminal is calculated based on all the reception time information transmitted from each base station, so that the reception time information of the base station that has received multipath is included. There is a problem that the position calculation error of the mobile terminal increases and the position of the mobile terminal cannot be calculated accurately.

  Accordingly, the present invention has been made to solve the above-described problems of the prior art, and an object of the present invention is to reduce the error in the position calculation of the mobile terminal and to calculate the position of the mobile terminal with high accuracy.

In order to solve the above-described problems and achieve the object, this positioning system receives reception time information that is information related to reception time at which each base station receives radio waves from a mobile terminal, and uses the received reception time information. Then, the position of the mobile terminal is calculated. Then, the positioning system uses the position of the mobile terminal and the position information of each base station to reversely calculate the reception time (back calculation reception time), and sequentially sets one of the base stations as a reference station. As the evaluation information, the difference between the reception time information of the base station other than the reference station and the reverse calculation reception time information is obtained by subtracting the difference between the reception time information of the reference station and the reverse calculation reception time information. The average of the values is calculated as the evaluation result of the reference station . Subsequently, the positioning system determines whether the evaluation result is equal to or less than a predetermined threshold. If the evaluation result is equal to or less than the predetermined threshold, the reference station having the evaluation result is used for calculating the position of the mobile terminal. The base station is selected, and the position of the mobile terminal is calculated again using the reception time information of the selected base station.

  The disclosed system has the effect of reducing the error in the position calculation of the mobile terminal and calculating the position of the mobile terminal with high precision even when a base station for multipath reception exists.

FIG. 1 is a block diagram illustrating the configuration of the computer according to the first embodiment. FIG. 2 is a diagram illustrating an example of a data structure of the base station management table. FIG. 3 is a diagram for explaining the difference between the back-calculated value and the actually measured value and the variation. FIG. 4 is a diagram for explaining the base station selection process. FIG. 5 is a block diagram illustrating the configuration of the base station according to the first embodiment. FIG. 6 is a block diagram illustrating the configuration of the mobile terminal according to the first embodiment. FIG. 7 is a flowchart for explaining the processing procedure of the computer according to the first embodiment. FIG. 8 is a flowchart for explaining the processing procedure of the computer according to the second embodiment. FIG. 9 is a flowchart for explaining the processing procedure of the computer according to the third embodiment. FIG. 10 is a diagram for explaining weighting calculation processing based on past data. FIG. 11 is a diagram illustrating a computer that executes a positioning program. FIG. 12 is a diagram for explaining a conventional positioning system. FIG. 13 is a diagram for explaining the prior art.

  Exemplary embodiments of a positioning system and a positioning method according to the present invention will be described below in detail with reference to the accompanying drawings.

  In the following embodiment, the configuration of the computer, the base station, and the mobile terminal in the positioning system according to the first embodiment, and the flow of processing will be described in order, and finally the effect of the first embodiment will be described. In each embodiment shown below, in order to accurately measure the reception time, an ultra-wideband wireless communication technique called UWB (ultra-wide band) is used, and an impulse wave with a very short time width is used. The communication used is adopted.

[Computer configuration]
First, the configuration of the computer 10 will be described with reference to FIG. FIG. 1 is a block diagram illustrating the configuration of the computer according to the first embodiment. FIG. 2 is a diagram illustrating an example of a data structure of the base station management table. FIG. 3 is a diagram for explaining the difference between the back-calculated value and the actually measured value and the variation. FIG. 4 is a diagram for explaining the base station selection process.

  As shown in FIG. 1, the computer 10 includes a communication unit 11, a control unit 12, and a storage unit 13, and is connected to the base station 20 via a communication cable. The processing of each of these units will be described below.

  The communication unit 11 controls communication related to various information exchanged with the connected base station 20. Specifically, the communication unit 11 receives, from each base station 20, reception time information that is information related to the reception time at which each base station 20 received a radio wave from the mobile terminal 30.

  The storage unit 13 stores data and programs necessary for various processes performed by the control unit 12, and particularly includes a base station management table 13a. This base station management table 13a is a table for managing the position of each base station 20, the actual measurement value of the reception time at which each base station 20 received the impulse radio wave, and the back calculation value back-calculated by the back-calculation value calculation unit 12c described later. is there.

  Specifically, as illustrated in FIG. 2, the base station management table 13a includes base station identification information that uniquely identifies the base station 20, a position (coordinates) of the base station, an actual measurement value of the reception time, The reception time inverse calculation value is stored in association with each other.

  The control unit 12 has an internal memory for storing a program that defines various processing procedures and necessary data, and performs various processes using these programs. In particular, the actual value receiving unit 12a, the first position calculation, and the like. A unit 12b, a reverse calculation value calculation unit 12c, a base station evaluation unit 12d, a base station selection unit 12e, and a second position calculation unit 12f.

  The actual measurement value reception unit 12a receives reception time information that is information related to the reception time at which each base station 20 receives a radio wave from the mobile terminal 30. Specifically, the actual measurement value receiving unit 12a receives the reception time information from each base station 20, and stores it in the base station management table 13a as the actual measurement value RTn.

  The first position calculation unit 12b calculates the position of the mobile terminal 30 using the received reception time information. Specifically, the first position calculation unit 12b calculates the position of the mobile terminal 30 using the measured value of each base station 20 from the base station management table 13a, and calculates the calculated position calculation result as a back-calculation value calculation unit. 12c is notified.

  The reverse calculation value calculation unit 12c performs reverse calculation of the reception time using the calculated position calculation result of the mobile terminal 30 and the position information of each base station 20. Specifically, when receiving the position calculation result of the mobile terminal 30 from the first position calculation unit 12b, the reverse calculation value calculation unit 12c reads the position (coordinates) of each base station 20 from the base station management table 13a. Then, the reverse calculation value calculation unit 12c calculates the reception time from the position calculation result and the position (coordinates) of each base station 20, and stores the reverse calculation value RTCn in the base station management table 13a.

  The base station evaluation unit 12d evaluates each base station using the difference between the actual measurement value of the reception time and the reverse calculation value of the reception time. Specifically, the base station evaluation unit 12d reads the actual measurement value and the reverse calculation value for each base station 20 from the base station management table 13a (see the left diagram in FIG. 3).

  Then, the base station evaluation unit 12d selects any one of the base stations as a reference station (in the example of FIG. 3, base station “0” is selected as the reference station). Here, as a reference station selection method, base stations may be selected in order of reception time. Here, an example in which the i-th base station is used as a reference station will be described.

  As illustrated in FIG. 3, the base station evaluation unit 12d makes the measured value and the reverse calculation value of the reference station the same (subtract the difference between the reception time RTi of the reference station and the reverse calculation reception time RTCi from either). Evaluation information of base stations other than the reference station is calculated by subtracting the difference (RTi−RTCi) between the reception time RTi of the reference station and the reverse reception time RTCi from the difference between the reception time RTn and the reverse reception time RTCn (FIG. (See right figure 3). Furthermore, an average (hereinafter referred to as “variation”) of evaluation information (difference between reception time and reverse calculation reception time) of base stations other than the reference station is calculated as an evaluation result. Then, the base station evaluation unit 12d calculates variations using all the base stations as reference stations, and notifies the base station selection unit 12e of the variations.

  Explaining in detail the “variation” calculation process, the base station evaluation unit 12d sets the difference between the back-calculated value RTCi of the reference station and the reception time RTi as an offset Δ (= RTCi−RTi). Thereafter, the base station evaluation unit 12d calculates RTCn−RTn−Δ as the difference between the back-calculated value of the base station other than the reference station and the actually measured value, and calculates the square value thereof. Thereafter, the base station evaluation unit 12d calculates a mean square value as the variation.

  In this way, the difference between reception times other than the reference station is calculated, and the presence or absence of multipath reception is determined by calculating the variation. That is, in an ideal situation where there is no multipath reception, the difference between the actual measurement value and the back calculation value should be about the reception accuracy (reception variation) of each base station 20. Therefore, when this variation is larger than necessary, it can be determined that multipath reception is included.

  The base station selection unit 12e selects a base station used for calculating the position of the mobile terminal among the base stations using the evaluation result of each evaluated base station. Specifically, the base station selection unit 12e receives each variation calculated using each base station 20 as a reference station from the base station evaluation unit 12d, and determines whether each variation is within a predetermined range.

  As a result, the base station selection unit 12e selects the base station of the reference station whose variation is within a predetermined range, and notifies the second position calculation unit 12f of the selection result. That is, as shown in FIG. 4, in the base station selection unit 12e, when there is a base station that has received multipaths, the reception time from the base station is not used for the position calculation of the mobile terminal. Only base stations that are excluded and used for calculation are selected.

  The second position calculation unit 12f calculates the position of the mobile terminal using the reception time information of the selected base station. Specifically, the second position calculation unit 12f receives the selection result from the base station selection unit 12e, and reads the measured value of the selected base station from the base station management table 13a. Then, the second position calculation unit 12f calculates the position of the mobile terminal 30 using the read actual measurement value of the reception time.

[Base station configuration]
Next, the configuration of the base station 20 will be described with reference to FIG. FIG. 5 is a block diagram illustrating the configuration of the base station 20 according to the first embodiment. As shown in FIG. 5, this base station 20 has a pulse detection unit 21, a correlator 22, a PN sequence generation unit 23, a timer 24, a reception time holding unit 25, a PPM data demodulation unit 26, and an MPU 27, and a communication cable. The computer 10 is connected via The processing of each of these units will be described below.

  When the pulse detector 21 receives a pulse train composed of a plurality of pulses used for positioning and data communication using an antenna, the pulse detector 21 measures the reception time for each received pulse, and the measured reception time and the measurement completion pulse are measured. Output to the correlator 22. The correlator 22 performs a correlation operation between the PN sequence generated in the PN sequence generator 23 and the measurement completion pulse, and obtains timing synchronization.

  The PN sequence generation unit 23 generates the same PN sequence that is used in each mobile terminal. For example, a PN (PseudoNoise, pseudo-noise) sequence such as a Reed-Solomon code is used. The timer 24 measures the time unique to the base station device 20. The timer 24 provides the current time in response to a request from the pulse detection unit. The reception time holding unit 25 holds the reception time in the measurement completion pulse at a predetermined position (for example, the first) at the timing synchronization by the correlator 22 and notifies the MPU 27 of the reception time.

  The PPM data demodulator 26 demodulates the pulse position from the pulse train based on the PN sequence used for timing synchronization and generates reception data. Then, the PPM data demodulator 26 outputs the obtained received data to the MPU 27.

  The MPU 27 transmits the reception data received from the PPM data demodulation unit 26 and the reception time received from the reception time holding unit 25 to the computer 10 via a communication cable.

[Configuration of mobile terminal]
Next, the configuration of the mobile terminal 30 will be described with reference to FIG. FIG. 6 is a block diagram illustrating the configuration of the mobile terminal 30 according to the first embodiment. As shown in the figure, the mobile terminal 30 includes an MPU 31, a PN system example generation unit 32, a PPM data modulation unit 33, and an impulse generation unit 34. The processing of each of these units will be described below.

  The MPU 31 controls processing of the entire mobile terminal device 30 and outputs transmission data to be transmitted to the base station device to the PPM data modulation unit 33 at the time of positioning.

  The PN system example generator 32 generates a unique PN sequence for each mobile terminal. The PPM data modulation unit 33 performs pulse position modulation on the transmission data using the PN sequence.

  The impulse generator 34 has a step recovery diode, for example, and generates an extremely short impulse at the timing of the pulse wave output from the PPM data modulator 33. Then, the impulse generator 34 outputs the generated impulse to the base station 20.

[Processing by computer]
Next, processing by the computer 10 according to the first embodiment will be described with reference to FIG. FIG. 7 is a flowchart illustrating the processing operation of the computer 10 according to the first embodiment.

  As shown in FIG. 7, the computer 10 receives reception time information (actually measured values) from each base station 20 (step S <b> 101), and calculates the position of the mobile terminal 30 using the reception time information of each base station 20. (Step S102).

  Subsequently, the computer 10 calculates back the reception time from the position calculation result and the position (coordinates) of each base station 20 (step S103). Thereafter, the computer 10 sets the i-th base station as the reference station, and sets the difference between the actually measured value and the reverse calculation value of the reference station as the offset Δ (step S104).

  Then, the computer 10 calculates, for each base station (base station other than the reference station), a square value obtained by further subtracting the offset Δ from the difference between the actually measured value and the back-calculated value (step S105). The average of the values is calculated as “variation” (step S106).

  Thereafter, the computer 10 determines whether or not all base stations are set as reference stations (step S107). If all base stations are not set as reference stations (No in step S107), the next base station (i + 1th base station) ) Is repeated as a reference station (steps S104 to S107).

  On the other hand, when all the base stations are set as the reference stations (Yes at Step S107), the computer 10 determines whether each variation calculated by using each base station 20 as the reference station is within a predetermined range (Step S108). .

  Then, the computer 10 selects only the base station of the reference station whose variation is within a predetermined range (step S109), and calculates the position of the mobile terminal using the reception time (actually measured value) of the selected base station. (Step S110).

[Effect of Example 1]
As described above, the computer 10 of the positioning system according to the first embodiment receives the reception time information, which is information related to the reception time at which each base station 20 receives the radio wave from the mobile terminal 30, and the received reception time information. Is used to calculate the position of the mobile terminal 30. Then, the computer 10 calculates the reverse reception time using the position of the mobile terminal 30 and the position information of each base station 20, and uses the difference between the received reception time information and the calculated reverse reception time. Then, each base station 20 is evaluated. Subsequently, the computer 10 uses the evaluation result of each evaluated base station to select a base station 20 to be used for calculating the position of the mobile terminal among the base stations 20. The position of the mobile terminal 30 is calculated using the reception time information. As a result, in the positioning system according to the first embodiment, using the difference between the received reception time information and the back-calculated reception time, it is determined whether the base station has a problem such as multipath, and so on. Therefore, the base station reception time of the base station having the problem is excluded from being used for the position calculation of the mobile terminal 30, and only the reception time of the base station without the problem is used for the position calculation process of the mobile terminal. Even when there is a station, it is possible to reduce the position calculation error of the mobile terminal and calculate the position of the mobile terminal with high accuracy.

  Further, according to the first embodiment, the computer 10 sequentially sets one base station among the base stations as a reference station, subtracts the difference between the reception time information of the reference station and the reverse calculation reception time information, and sets the base stations other than the reference station. The difference between the reception time information of the station and the reverse calculation reception time information is calculated. Then, the computer 10 calculates the average of the difference between the reception time information of the base station other than the reference station and the reverse calculation reception time information as “variation”, determines whether the variation is equal to or less than a predetermined threshold, and the variation is a predetermined threshold In the following cases, the reference station 20 is selected as a base station that can be used for calculating the position of the mobile terminal 30. As a result, in the positioning system according to the first embodiment, using the difference between the received reception time information and the back-calculated reception time, it is determined whether the base station has a problem such as multipath, and so on. Therefore, it is possible to exclude the reception time of the base station having the above problem from being used for the position calculation of the mobile terminal 30 and use only the reception time of the base station having no problem for the position calculation process of the mobile terminal. For this reason, even when a base station for multipath reception exists, it is possible to reduce the error in the position calculation of the mobile terminal and to calculate the position of the mobile terminal with high accuracy.

  By the way, in the computer of the positioning system of the present invention, if the propagation time difference that is the reception time difference between the base stations is larger than a predetermined threshold before calculating the position of the mobile terminal, the reception time of the base station is calculated. You may exclude beforehand so that it may not utilize for the position calculation of a mobile terminal.

  Therefore, in the second embodiment below, when the position of the mobile terminal is calculated, the propagation time difference that is the difference in reception time between the base stations is determined to exceed the maximum propagation time difference and exceeds the maximum propagation time difference. The processing of the computer 10a in the second embodiment will be described with reference to FIG. 8 as a case where the reception time of the base station is excluded from being used for the position calculation of the mobile terminal. FIG. 8 is a flowchart for explaining the processing procedure of the computer according to the second embodiment.

  Compared with the processing procedure of the computer 10 according to the first embodiment illustrated in FIG. 7, the processing procedure of the computer 10 a according to the second embodiment is based on the reception time difference between the base stations before calculating the position of the mobile terminal. It is determined whether or not a certain propagation time difference exceeds the maximum propagation time difference, and when the difference exceeds the maximum propagation time difference, the reception time of the base station is excluded so as not to be used for the position calculation of the mobile terminal.

That is, as shown in FIG. 8, the computer 10a calculates the maximum time difference Tmax ij between the base station i and the base station j from the position coordinates P _{1 to} P _{n of} each base station before calculating the position of the mobile terminal. (Step S201). The maximum propagation time difference Tmax ij between the base station i and the base station j is determined from the coordinates of the base station i and the base station j.

  Then, the computer 10a receives the reception time (actual value) from each base station (step S202). Thereafter, the computer 10a calculates the reception time difference of the actual measurement value used for the positioning calculation from the reception time, and determines whether or not the maximum time difference is exceeded (step S203).

  As a result, when the reception time difference exceeds the maximum time difference, the computer 10a excludes it from the positioning calculation use data (step S204). By doing so, it is possible to exclude the reception time of the base station, which is clearly an abnormally measured value, from being used for the position calculation of the mobile terminal. The subsequent processing is the same as the processing procedure of the computer 10 according to the first embodiment shown in FIG. 7 (steps S205 to S212).

  Thus, in the computer 10a of the positioning system according to the second embodiment, the maximum time difference between the base stations is calculated from the position of each base station 20, and the reception time information of each base station 20 received is used. The reception time difference between the base stations is calculated, and it is determined whether the reception time difference exceeds the calculated maximum time difference. When it is determined that the reception time difference exceeds the maximum time difference, the computer 10a excludes the reception time information about the base station related to the reception time difference from being used for the position calculation of the mobile terminal 30. To do. For this reason, in the positioning system according to the second embodiment, it is possible to exclude the reception time of the base station, which is clearly an abnormally measured value, from being used for the position calculation of the mobile terminal. Thus, the position of the mobile terminal can be calculated with higher accuracy.

  By the way, in the computer of the positioning system of the present invention, the position of the mobile terminal may be calculated using the position calculation result of the immediately preceding mobile terminal.

  Therefore, in Example 3 below, it is determined whether the position calculation result of the immediately preceding mobile terminal is correct. If it is determined that the position calculation result of the immediately preceding mobile terminal is correct, the position calculation result of the immediately preceding mobile terminal is determined. As a case where the position of the mobile terminal is calculated using FIG. 9, the processing of the computer 10b in the third embodiment will be described using FIG. FIG. 9 is a flowchart for explaining the processing procedure of the computer according to the third embodiment.

  Compared with the processing procedure of the computer 10 according to the first embodiment illustrated in FIG. 7, the processing procedure of the computer 10 b according to the third embodiment uses the position calculation result of the immediately preceding mobile terminal to determine the position of the mobile terminal. The point of calculation is different. That is, in the computer 10b according to the third embodiment, if the transmission interval of the radio waves to be measured is sufficiently faster than the moving speed of the mobile terminal, the moving amount can be ignored before and after the two positionings. As a result, there is almost no change in the difference in propagation time between before and after. Based on this assumption, a comparison is made with the previous reception result. However, only the data when it is determined that the previous result is correct in the position calculation result is used.

  That is, as shown in FIG. 9, the computer 10b determines that the previous position calculation result is correct (for example, there is no multipath receiving base station or the multipath receiving base station before calculating the position of the mobile terminal). (Step S301). For the determination, for example, a step of calculating variation in the first embodiment is applied. For the positioning result after selecting the base station, the same reverse calculation and step for obtaining the variation are performed, and if the variation is within a predetermined range, it is determined that the position is correct. As a result, when it is determined that the previous position calculation result is not correct (No at Step S301), the computer 10b does not store the previous position calculation result of the mobile terminal (Step S311) and ends the process.

  On the other hand, when the computer 10b determines that the previous position calculation result is correct (Yes at step S301), the computer 10b stores the reception time (actual value) of each base station selected to be used for the previous positioning calculation (step S301). S302) Wait until the next reception time becomes possible to calculate the positioning (step S303). The computer 10b then sets the i-th base station as the reference station at the stage when the next reception time is complete and positioning calculation is possible (step S304), and the difference between the current reception time and the stored reception time is calculated. The absolute value is calculated (step S305), and the sum (difference sum) is obtained (step S306).

  Thereafter, the computer 10b determines whether the calculation has been performed for all the base stations (step S307). If the calculation has not been performed for all the base stations (No in step S307), the base station serving as the reference station is changed in order. The above process is repeated (steps S304 to S307).

  If the calculation can be performed by all the base stations (Yes at Step S307), the computer 10b sets the base station having the smallest difference sum as the correct reference station (Step S308). If the absolute value of the difference in each base station at this time is within a predetermined range, it is used for the position calculation process of the mobile terminal, and the base station reception time is made unavailable by excluding the other base stations from the calculation. (Step S309). The range value used for determination is set as appropriate based on the transmission interval and the moving speed.

  Thereafter, the computer 10b calculates the position of the mobile terminal using the reception time of the base station used for the position calculation process of the mobile terminal (step S310).

  As described above, the computer 10b of the positioning system according to the third embodiment stores the reception time information of the base station used for calculating the position of the selected mobile terminal as the previous reception time information, and is received. The difference between the current reception time information and the stored previous reception time information is calculated for each base station. Then, the computer 10b determines for each base station whether the calculated difference is equal to or less than a predetermined threshold, and if the difference is within the predetermined threshold, the base station used for calculating the position of the mobile terminal Select as station. For this reason, in the positioning system according to the third embodiment, when there is almost no change in the difference between the propagation times before and after, the position calculation error of the mobile terminal 30 can be further reduced and the position of the mobile terminal can be calculated with higher accuracy. Is possible.

  By the way, in the computer of the positioning system of the present invention, weighting may be performed at the time of positioning calculation using the reception time data determined to be correct in the past.

  Therefore, in the following fourth embodiment, the processing of the computer 10c in the fourth embodiment will be described using FIG. 10 as a case where weighting is performed at the time of positioning calculation using reception time data determined to be correct in the past. FIG. 10 is a diagram for explaining weighting calculation processing based on past data.

  In the computer 10c according to the fourth embodiment, as illustrated in FIG. 10, the reception time is estimated from the plurality of reception times that are not past multipath receptions by using an approximate straight line. This can be calculated if the transmission interval of the mobile terminal is known. The computer 10c takes the difference between the estimated value and the actually measured value, and uses the reciprocal as a base station weighting factor.

  Then, the computer 10c establishes an equation for each propagation time difference between the two base stations and solves the simultaneous equations by the least square method as the position calculation processing of the mobile terminal. When calculating the position of the mobile terminal, the computer 10c needs to apply a weighting factor to the equation corresponding to each propagation time difference. Therefore, the weighting coefficient in the equation is the mean square value of the two base station weighting coefficients for which the propagation time difference is calculated. Note that the weighting coefficient of the equation may be determined differently, such as the larger of the two base station weighting coefficients, instead of the mean square.

  As described above, the computer 10c of the positioning system according to the fourth embodiment estimates the current estimated reception time using a plurality of past reception time information, and is estimated as the received current reception time information. The difference from the estimated reception time is calculated, and the reciprocal of the difference is calculated as a weighting coefficient. And the computer 10c calculates the position of the mobile terminal 30 using the calculated weighting coefficient. For this reason, in the positioning system according to the fourth embodiment, as a result of performing weighting at the time of positioning calculation using the past reception time data, the error of the position calculation of the mobile terminal 30 is further reduced, and the position of the mobile terminal is more accurately determined. It is possible to calculate.

  Although the embodiments of the present invention have been described so far, the present invention may be implemented in various different forms other than the embodiments described above. Therefore, another embodiment will be described below as a fifth embodiment.

(1) Base station selection In the first embodiment, the case where the reference station is set and the variation of each reference station is calculated and the base station used for position calculation is selected based on the variation has been described. The example is not limited to this, and the computer determines whether or not the difference between the actual measurement value of the reception time and the reverse calculation value of the reception time is within a predetermined threshold as the base station selection process. For example, the reception time may be excluded so as not to be used for the position calculation of the mobile terminal, and if it is within a predetermined threshold, it may be selected as a base station used for the position calculation process of the mobile terminal.

  As described above, in the computer of the positioning system according to the fifth embodiment, the base station having a problem such as multipath is easily determined using the difference between the actual measurement value of the reception time and the reverse calculation value of the reception time. Even when there is a receiving base station, it is possible to reduce the error in calculating the position of the mobile terminal and calculate the position of the mobile terminal with high accuracy.

(2) System Configuration The components of the illustrated devices are functionally conceptual and need not be physically configured as illustrated. In other words, the specific form of distribution / integration of each device is not limited to that shown in the figure, and all or a part thereof may be functionally or physically distributed or arbitrarily distributed in arbitrary units according to various loads or usage conditions. Can be integrated and configured. For example, the base station evaluation unit 12d and the base station selection unit 12e may be integrated. Further, all or any part of each processing function performed in each device may be realized by a CPU and a program analyzed and executed by the CPU, or may be realized as hardware by wired logic.

  In addition, among the processes described in this embodiment, all or part of the processes described as being performed automatically can be performed manually, or the processes described as being performed manually can be performed. All or a part can be automatically performed by a known method. In addition, the processing procedure, control procedure, specific name, and information including various data and parameters shown in the above-described document and drawings can be arbitrarily changed unless otherwise specified.

(3) Program By the way, various processes described in the above embodiments can be realized by executing a program prepared in advance by a computer. In the following, an example of a computer that executes a program having the same function as that of the above-described embodiment will be described with reference to FIG. FIG. 11 is a diagram illustrating a computer that executes an immediate program.

  As shown in the figure, a computer 600 as a computer is configured by connecting an HDD 610, a RAM 620, a ROM 630 and a CPU 640 via a bus 650.

  In the ROM 630, a positioning program that exhibits the same function as in the above-described embodiment, that is, as shown in FIG. 11, an actual measurement value reception program 631, a first position calculation program 632, a reverse calculation value calculation program 633, a base station An evaluation program 634, a base station selection program 635, and a second position calculation program 636 are stored in advance. Note that the programs 631 to 636 may be appropriately integrated or distributed in the same manner as each component of the computer 10 illustrated in FIG.

  Then, the CPU 640 reads out these programs 631 to 636 from the ROM 630 and executes them, so that each program 631 to 636 has an actually measured value reception process 641, a first position calculation process 642, and a reverse calculation value as shown in FIG. Functions as a calculation process 643, a base station evaluation process 644, a base station selection process 645, and a second position calculation process 646. Each of the processes 641 to 646 includes the actual measurement value reception unit 12a, the first position calculation unit 12b, the reverse calculation value calculation unit 12c, the base station evaluation unit 12d, the base station selection unit 12e, and the second position calculation unit 12f illustrated in FIG. Each corresponds.

  The CPU 640 stores the base station management table 621 in the RAM 620, and executes processing based on the base station management table 621 stored in the RAM 620.

  The following appendices are further disclosed with respect to the embodiments including Examples 1 to 5 described above.

(Supplementary Note 1) A reception time receiving unit that receives reception time information that is information related to the reception time at which each base station receives radio waves from a mobile terminal;
A first position calculation unit that calculates a position of the mobile terminal using the reception time information received by the reception time reception unit;
A reception time reverse calculation unit that reversely calculates a reverse calculation reception time using the position of the mobile terminal calculated by the first position calculation unit and the position information of each base station;
A base station evaluation unit that evaluates each base station using a difference between the reception time information received by the reception time reception unit and the reverse calculation reception time calculated by the reception time reverse calculation unit;
Using the evaluation result of each base station evaluated by the base station evaluation unit, a base station selection unit that selects a base station used for calculating the position of the mobile terminal among the base stations,
A second position calculating unit that calculates the position of the mobile terminal using the reception time information of the base station selected by the base station selecting unit;
A positioning system comprising:

(Supplementary Note 2) The base station evaluation unit sequentially sets one base station among the base stations as a reference station, and receives the reception time information of the base stations other than the reference station and the reverse calculation reception time as evaluation information of the base stations other than the reference station The difference between the information is calculated by subtracting the difference between the reception time information of the reference station and the reverse calculation reception time information, respectively, and the average of the evaluation information of base stations other than the reference station is calculated as the evaluation result,
The base station selection unit determines whether an average of the evaluation information calculated by the base station evaluation unit is equal to or less than a predetermined threshold, and if the average of the evaluation information is equal to or less than a predetermined threshold, the evaluation The positioning system according to supplementary note 1, wherein an average reference station of information is selected as a base station used for position calculation of the mobile terminal.

(Supplementary Note 3) A maximum time difference calculating unit that calculates a maximum time difference between base stations from the position of each base station;
Using the reception time information of each base station received by the reception time reception unit, the reception time difference between the base stations is calculated, and the reception time difference is calculated by the maximum time difference calculation unit. A maximum time difference determination unit for determining whether the difference is exceeded;
When the maximum time difference determination unit determines that the reception time difference exceeds the maximum time difference, a base that excludes the base station having the reception time difference from being used for position calculation of the mobile terminal The station exclusion section,
The positioning system according to appendix 1 or 2, further comprising:

(Supplementary Note 4) A reception time information storage unit that stores, as the previous reception time information, the reception time information of the base station used for calculating the position of the mobile terminal selected by the base station selection unit;
A difference calculation unit that calculates a difference between the current reception time information received by the reception time reception unit and the previous reception time information stored by the reception time information storage unit for each base station;
It is determined for each base station whether the difference calculated by the difference calculation unit is equal to or less than a predetermined threshold, and if the difference is within a predetermined threshold, the reference station of the difference is used to calculate the position of the mobile terminal. 4. The positioning system according to any one of appendices 1 to 3, wherein the positioning system is selected as a base station to be used.

(Supplementary Note 5) A reception time estimation unit that estimates a current estimated reception time using a plurality of past reception time information;
A weighting factor calculation unit that calculates a difference between current reception time information received by the reception time receiving unit and the estimated reception time estimated by the reception time estimation unit, and calculates an inverse of the difference as a weighting factor And further comprising
Said 2nd position calculation part calculates the position of the said mobile terminal using the said weighting coefficient calculated by the said weighting coefficient calculation part, The appendix 1-4 characterized by the above-mentioned Positioning system.

(Appendix 6) A reception time reception step of receiving reception time information, which is information related to the reception time at which each base station receives radio waves from a mobile terminal;
A first position calculating step of calculating the position of the mobile terminal using the reception time information received by the reception time receiving step;
A reception time reverse calculation step of reversely calculating a reverse reception time using the position of the mobile terminal calculated by the first position calculation step and the position information of each base station;
A base station evaluation step for evaluating each base station using a difference between the reception time information received by the reception time reception step and the reverse calculation reception time calculated by the reception time reverse calculation step;
Using the evaluation result of each base station evaluated in the base station evaluation step, a base station selection step for selecting a base station used for calculating the position of the mobile terminal among the base stations,
A second position calculating step of calculating the position of the mobile terminal using the reception time information of the base station selected by the base station selecting step;
A positioning method characterized by including.

(Supplementary note 7) A reception time reception procedure for receiving reception time information, which is information related to reception time at which each base station receives radio waves from a mobile terminal,
Using the reception time information received by the reception time reception procedure, a first position calculation procedure for calculating the position of the mobile terminal;
A reception time reverse calculation procedure that reversely calculates a reverse calculation reception time using the position of the mobile terminal calculated by the first position calculation procedure and the position information of each base station;
A base station evaluation procedure for evaluating each base station using a difference between the reception time information received by the reception time reception procedure and the reverse calculation reception time calculated by the reception time reverse calculation step;
Using the evaluation result of each base station evaluated by the base station evaluation procedure, among the base stations, a base station selection procedure for selecting a base station used for position calculation of the mobile terminal,
A second position calculation procedure for calculating the position of the mobile terminal using the reception time information of the base station selected by the base station selection procedure;
A positioning program for causing a computer to execute.

(Supplementary Note 8) A reception time receiving unit that receives reception time information that is information related to the reception time at which each base station receives radio waves from a mobile terminal;
A first position calculation unit that calculates a position of the mobile terminal using the reception time information received by the reception time reception unit;
A reception time reverse calculation unit that reversely calculates a reverse calculation reception time using the position of the mobile terminal calculated by the first position calculation unit and the position information of each base station;
A base station evaluation unit that evaluates each base station using a difference between the reception time information received by the reception time reception unit and the reverse calculation reception time calculated by the reception time reverse calculation unit;
Using the evaluation result of each base station evaluated by the base station evaluation unit, a base station selection unit that selects a base station used for calculating the position of the mobile terminal among the base stations,
A second position calculating unit that calculates the position of the mobile terminal using the reception time information of the base station selected by the base station selecting unit;
A computer comprising:

10, 10a, 10b, 10c Computer 11 Communication unit 12 Control unit 12a Actual measurement value receiving unit 12b First position calculation unit 12c Back calculation value calculation unit 12d Base station evaluation unit 12e Base station selection unit 12f Second position calculation unit 13 Storage unit 13a Base station management table 20 Base station 21 Pulse detection unit 22 Correlator 23 PN sequence generation unit 24 Timer 25 Reception time holding unit 26 PPM data demodulation unit 27 MPU
30 Mobile terminal 31 MPU
32 PN system example generator 33 PPM data modulator 34 Impulse generator

Claims (5)

A reception time receiving unit that receives reception time information that is information related to the reception time at which each base station received radio waves from the mobile terminal;
A first position calculation unit that calculates a position of the mobile terminal using the reception time information received by the reception time reception unit;
A reception time reverse calculation unit that reversely calculates a reverse calculation reception time using the position of the mobile terminal calculated by the first position calculation unit and the position information of each base station;
One base station of each base station is sequentially set as a reference station, and the reception time information of the reference station and the reverse calculation reception are obtained from the difference between the reception time information of the base station other than the reference station and the reverse calculation reception time information as the evaluation information of the reference station. A base station evaluation unit that calculates the difference between the time information, respectively, and calculates the average of the calculated values as the evaluation result of the reference station;
It is determined whether or not the evaluation result calculated by the base station evaluation unit is equal to or less than a predetermined threshold value. a base station selector which selects a base station to be used for,
A second position calculating unit that calculates the position of the mobile terminal using the reception time information of the base station selected by the base station selecting unit;
A positioning system comprising: A reception time estimation unit that estimates a current estimated reception time using a plurality of past reception time information,
A weighting factor calculation unit that calculates a difference between current reception time information received by the reception time receiving unit and the estimated reception time estimated by the reception time estimation unit, and calculates an inverse of the difference as a weighting factor And further comprising
The positioning system according to claim 1, wherein the second position calculation unit calculates the position of the mobile terminal by using the weighting factor calculated by the weighting factor calculation unit. A maximum time difference calculator for calculating a maximum time difference between base stations from the position of each base station;
Using the reception time information of each base station received by the reception time reception unit, the reception time difference between the base stations is calculated, and the reception time difference is calculated by the maximum time difference calculation unit. A maximum time difference determination unit for determining whether the difference is exceeded;
When the maximum time difference determination unit determines that the reception time difference exceeds the maximum time difference, a base that excludes the base station having the reception time difference from being used for position calculation of the mobile terminal The station exclusion section,
The positioning system according to claim 1, further comprising: A reception time information storage unit that stores, as previous reception time information, reception time information of a base station used for position calculation of the mobile terminal selected by the base station selection unit;
A difference calculation unit that calculates a difference between the current reception time information received by the reception time reception unit and the previous reception time information stored by the reception time information storage unit for each base station;
It is determined for each base station whether the difference calculated by the difference calculation unit is equal to or less than a predetermined threshold, and if the difference is within a predetermined threshold, the base station of the difference is calculated for the position of the mobile terminal. The positioning system according to any one of claims 1 to 3, wherein the positioning system is selected as a base station to be used in the operation. A reception time reception step of receiving reception time information, which is information related to the reception time at which each base station receives radio waves from the mobile terminal;
A first position calculating step of calculating the position of the mobile terminal using the reception time information received by the reception time receiving step;
A reception time reverse calculation step of reversely calculating a reverse reception time using the position of the mobile terminal calculated by the first position calculation step and the position information of each base station;
One base station of each base station is sequentially set as a reference station, and the reception time information of the reference station and the reverse calculation reception are obtained from the difference between the reception time information of the base station other than the reference station and the reverse calculation reception time information as the evaluation information of the reference station. Subtracting the difference between the time information, each calculated, base station evaluation step to calculate the average of the calculated value as the evaluation result of the base station,
It is determined whether the evaluation result calculated by the base station evaluation unit is a predetermined threshold value or less. If the evaluation result is a predetermined threshold value or less, the reference station having the evaluation result is calculated as the position of the mobile terminal. A base station selection step of selecting as a base station to be used for
A second position calculating step of calculating the position of the mobile terminal using the reception time information of the base station selected by the base station selecting step;
A positioning method characterized by including.

Images