JP6681617B2 - Wave source position estimating apparatus, program to be executed by computer, and computer-readable recording medium recording the program - Google Patents

Description

  The present invention relates to a wave source position estimating device, a program to be executed by a computer, and a computer-readable recording medium recording the program.

  The secondary use of the frequency can be used within a range that does not affect the primary user. Therefore, in order to increase the frequency utilization efficiency, the secondary utilization of the frequency is being studied.

  In order to determine whether or not the frequency is secondarily used, it is necessary to detect whether or not the frequency is firstly used. Then, in order to detect the presence or absence of the primary use of the frequency, it is necessary to estimate the wave source position.

  Conventionally, the method described in Non-Patent Document 1 is known as a method for estimating the wave source position. In the method described in Non-Patent Document 1, the source position is estimated using TDoA (Time Differential of Arrival).

  More specifically, a high-precision sensor called a long-distance sensor is used to receive radio waves from a wave source, and the wave source is estimated from differences in arrival times of radio waves to a plurality of sensors.

That is, the arrival time difference when coming from radio waves wave source two sensors _S A, the _{S B |} t a -t _{b |} is calculated. Then, the arrival time difference _| t a -t _{b |} with propagation distance difference when the radio wave arrives from the wave source sensor _S A, the _{S B |} L a -L _{b |} is calculated.

Similarly, the propagation distance difference | L _b −L _c | when a radio wave arrives from the wave source to the sensors S _B and S _C and the propagation distance difference | when a radio wave arrives from the wave source to the sensors S _C and S _A. And calculate L _c −L _a |.

Then, three hyperbolas | L _a −L _b |, | L _b −L _c |, | L _c −L _a | are drawn, and the intersection of the three hyperbolas is estimated as the source position.

Kenji Horibata, Issei Kanno, Rei Furukawa, Akira Hasegawa, Yoshio Takeuchi, “A study of elemental technology for local white space estimation by heterogeneous sensors,” 2014 IEICE General Conference, Proc. 17-28, p607.

  However, the estimation method described in Non-Patent Document 1 has a problem that it is necessary to synchronize the sensors and a high-performance system is required. There is also a problem that the amount of calculation becomes large for estimating the wave source position.

  The problem becomes more pronounced as the area and frequency range monitored increases.

  Therefore, according to the embodiment of the present invention, there is provided a wave source position estimating device capable of easily estimating the wave source position while suppressing the amount of calculation.

  Further, according to the embodiment of the present invention, there is provided a program for suppressing the amount of calculation and causing a computer to execute a simple estimation of a wave source position.

  Further, according to the embodiment of the present invention, there is provided a computer-readable recording medium in which a program for suppressing a calculation amount and causing a computer to execute a simple estimation of a wave source position is recorded.

  According to the embodiment of the present invention, the wave source position estimating device includes a receiving unit, a calculating unit, and an estimating unit. The receiving means receives, from a plurality of terminal devices, terminal information including position information of the terminal device, which is a mobile terminal or a stationary terminal, and received power at the terminal device. The calculating means calculates the variance in the distribution of the positions of the plurality of terminal devices based on the plurality of position information included in the plurality of terminal information of the plurality of terminal devices. The estimating means, when the calculated variance is equal to or larger than the first threshold value, the plurality of terminal devices weighted by the reception power based on the plurality of position information and the plurality of reception powers included in the plurality of terminal information. Is estimated as the wave source position, and when the calculated variance is smaller than the first threshold value, the two positions indicated by the position information of the two terminal devices among the plurality of terminal devices are externally divided. It is obtained by executing the process of obtaining an interior dividing point that internally divides the minute point or the two positions for all two terminal devices of the plurality of terminal devices and averaging the obtained outer dividing points or inner dividing points. The estimated position is estimated as the source position.

  According to the embodiment of the present invention, the wave source position estimating device has a center of gravity of a plurality of terminal devices weighted by received power, an average value of internal division points internally dividing two positions of two terminal devices, or two. The average value of the external dividing points is estimated as the wave source position. As a result, the wave source position estimating device can estimate the wave source position using four arithmetic operations.

  Therefore, it is possible to easily estimate the wave source position while suppressing the amount of calculation.

  Further, since the wave source position estimation device estimates the average value of the internal division points or the average value of the external division points as the wave source position, the wave source position can be accurately estimated even if the position of the terminal device is biased.

  Further, according to the embodiment of the present invention, the program to be executed by the computer is a program for causing the computer to execute estimation of the wave source position, and the receiving means is a terminal device including a mobile terminal or a stationary terminal. A first step of receiving from the plurality of terminal devices terminal information that includes the position information of the terminal device and the received power at the terminal device; And a second step of calculating the variance in the distribution of the positions of the plurality of terminal devices, and the estimating means calculates the plurality of position information and the plurality of terminal information when the calculated variance is equal to or more than the first threshold. The center of gravity of the plurality of terminal devices weighted by the received power based on the included received powers is estimated as the wave source position, and the calculated dispersion is the first threshold value. Is smaller, a process of obtaining an external division point that externally divides two positions indicated by position information of two terminal apparatuses of the plurality of terminal apparatuses or an internal division point that internally divides the two positions is performed by the plurality of terminal apparatuses. A third step of estimating the position obtained by averaging the obtained external and internal division points as a wave source position.

  By executing the program, the center of gravity of the plurality of terminal devices weighted by the reception power, the average value of the internally dividing points obtained by internally dividing the two positions of the two terminal devices, or the outside dividing point obtained by dividing the two positions by the outside The average value is estimated as the source position. As a result, the wave source position can be estimated using the four arithmetic operations.

  Therefore, it is possible to easily estimate the wave source position while suppressing the amount of calculation.

  Further, according to the embodiment of the present invention, the computer-readable recording medium recording the program is a computer-readable recording medium recording the program according to any one of claims 6 to 10. is there.

  The source position can be estimated easily by suppressing the amount of calculation.

It is a figure which shows the radio | wireless communications system in embodiment of this invention. It is the schematic of the wave source position estimation apparatus shown in FIG. It is a figure which shows the relationship between received power and the distance from a wave source. The center of gravity (x _{G, y G)} is a diagram showing a calculation result in the estimation method to the wave source position. The center of gravity (x _{G, y G)} are diagrams for explaining a problem of the estimation method and the wave source position. The center of gravity (x _{G, y G)} is another diagram for explaining a problem of the estimation method and the wave source position. It is a figure for demonstrating the estimation method of a wave source position in case the wave source position is lopsided to one side with respect to the distribution area of the terminal device 2. It is a figure for demonstrating the discriminating | determining method which uses an external dividing point and an internal dividing point. 3 is a flowchart for explaining the operation of the wave source position estimating device shown in FIG. 1. 6 is a flowchart for explaining another operation of the wave source position estimating device shown in FIG. 1. It is the schematic which shows the other structure of the wave source position estimation apparatus shown in FIG. It is a conceptual diagram which shows the fluctuation | variation of the received power by time. It is a figure which shows the relationship between the kind of error and the required reliability. It is a figure which shows the relationship between the size n of a sample, and the error range e. It is a figure which shows the sample in the case of determining whether received power is correct data. 12 is a flowchart for explaining the operation of the wave source position estimating device shown in FIG. 11.

  Embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts will be denoted by the same reference characters and description thereof will not be repeated.

  FIG. 1 is a diagram showing a wireless communication system according to an embodiment of the present invention.

  Referring to FIG. 1, a wireless communication system 10 includes a wave source position estimating device 1 and a plurality of terminal devices 2.

  The wave source position estimating device 1 and the plurality of terminal devices 2 are arranged in a wireless communication space. The plurality of terminal devices 2 and the wave source S are arranged in the observation area REG. The observation area REG has a circular shape centered on the wave source S.

  Each of the plurality of terminal devices 2 is a mobile terminal or a stationary terminal. Then, each of the plurality of terminal devices 2 detects its own position by, for example, GPS (Global Positioning System).

Further, each of the plurality of terminal devices 2 receives the radio wave from the wave source S and detects the received power P _i (i = 1, 2, 3, ...) When the radio wave is received.

Furthermore, each of the plurality of terminal devices 2 detects the time when the reception power P _i is detected.

Then, each of the plurality of terminal devices 2 includes position information (x _i , y _i ) indicating its own position, received power P _i, and time information indicating the time when the received power P _i is detected. The terminal information is generated, and the generated terminal information is transmitted to the wave source position estimating device 1 by wireless communication.

  The wave source position estimation device 1 receives a plurality of terminal information from a plurality of terminal devices 2 and estimates the wave source position, which is the position of the wave source S, by a method described below based on the received plurality of terminal information.

  FIG. 2 is a schematic diagram of the wave source position estimating device 1 shown in FIG. With reference to FIG. 2, the wave source position estimating device 1 includes an antenna 11, a receiving unit 12, a storing unit 13, a calculating unit 14, and an estimating unit 15.

  The receiving means 12 receives a plurality of terminal information from the plurality of terminal devices 2 via the antenna 11, and stores the received plurality of terminal information in the storage means 13.

  The storage unit 13 stores the plurality of terminal information received from the receiving unit 12.

  The calculation unit 14 reads out a plurality of terminal information from the storage unit 13, and calculates the variance Var in the distribution of the positions of the plurality of terminal devices 2 based on the plurality of position information included in the read plurality of terminal information. Then, the calculation unit 14 outputs the calculated variance Var to the estimation unit 15.

The estimation unit 15 receives the variance Var from the calculation unit 14 and reads out a plurality of terminal information from the storage unit 13. Then, the estimation means 15 compares the variance Var with the threshold value Var_th, and according to the comparison result, the plurality of position information (x _i , y _i ) and the plurality of received powers P _i included in the plurality of terminal information. The source position is estimated based on

  The method of estimating the wave source position will be described.

The estimating unit 15 calculates the centers of gravity (x _G , y _G ) of the plurality of terminal devices 2 by the following equation.

In Expression (1), w _i represents the weight of the i-th terminal device 2, and is composed of the reception power P _i in the i-th terminal device 2.

Then, the estimating means 15 estimates the center of gravity (x _G , y _G ) calculated by the equation (1) as the wave source position. That is, the estimation means 15 estimates the center of gravity (x _G , y _G ) of the plurality of terminal devices 2 weighted by the received power P _i as the wave source position.

  FIG. 3 is a diagram showing the relationship between the received power and the distance from the wave source. In FIG. 3, the vertical axis represents the received power and the horizontal axis represents the distance from the wave source S.

Referring to FIG. 3, the received power P _i is attenuated in inverse proportion to the distance from the wave source S. As a result, the received power P _i becomes larger as it gets closer to the wave source S, so that the effect of weighting by the received power P _i is greater near the wave source S. Therefore, the estimated value estimated by the estimation method using the center of gravity (x _G , y _G ) as the wave source position approaches the wave source vicinity.

FIG. 4 is a diagram showing a calculation result in the estimation method using the center of gravity (x _G , y _G ) as the wave source position.

  The wave source S was arranged at the position of (300, 300) in the xy coordinates. The number of terminal devices 2 is 50. The white circles in FIG. 4 represent the terminal device 2. The radius of the observation area is 1000 m.

The position of the center of gravity (x _G , y _G ) calculated using Expression (1) was (295, 306).

Therefore, it was found that the estimated value is located near the wave source S by setting the center of gravity (x _G , y _G ) calculated using the formula (1) as the wave source position.

FIG. 5 is a diagram for explaining the problems of the estimation method in which the center of gravity (x _G , y _G ) is the source position.

  In FIG. 5, the circle represents the position of the center of gravity, and the square represents the position of the wave source.

  With reference to FIG. 5A, when the distribution of the terminal devices 2 is uniform, the position of the center of gravity is accurately located near the wave source position.

On the other hand, when the distribution of the terminal devices 2 is biased, the center of gravity position is significantly different from the wave source position. The center of gravity (x _G , y _G ) calculated using equation (1) is located closer to the center of the region in which the terminal devices 2 are distributed, so that the distribution regions of the plurality of terminal devices 2 are located at the wave source position. On the other hand, when it is biased to one side, the center of gravity position is not located near the wave source position.

FIG. 6 is another diagram for explaining the problem of the estimation method in which the center of gravity (x _G , y _G ) is the source position.

  In FIG. 6, the position, the wave source position, and the center of gravity of the terminal device 2 are shown in the x-axis direction, and the change in the received power in the x-axis direction is shown.

  6A shows a case where the wave source position exists between two terminal devices, and FIG. 6B shows a case where the wave source position exists on one side of the two terminal devices 2.

  In FIGS. 6A and 6B, the received power is attenuated in inverse proportion to the distance from the wave source position.

  When the wave source position exists between the two terminal devices, the center-of-gravity position exists near the wave source position.

  On the other hand, when the wave source position exists on one side of the two terminal devices 2, the center of gravity position exists between the two terminal devices and is largely deviated from the wave source position.

  Thus, even in one dimension, when the wave source position is biased to one side of the terminal device, the position of the center of gravity is largely displaced from the wave source position.

  FIG. 7 is a diagram for explaining a method of estimating the wave source position when the wave source position is biased to one side with respect to the distribution area of the terminal device 2.

When the positions of the terminal device 2-1 and the terminal device 2-2 are close to each other, the position (x ₁ , y ₁ ) of the terminal device 2-1 and the position (x ₂ , y ₂ ) of the terminal device 2-2. The point (x _E , y _E ) that externally divides and into w ₁ : w ₂ is estimated as the wave source position.

In this case, x _E and y _E are represented by the following equations.

  Referring to the distribution of the received power according to the distance, since the wave source is biased to the right side of the terminal devices 2-1 and 2-2 on the paper surface of FIG. 7, the received power of the terminal device 2-2 is It is larger than the received power of 2-1.

Therefore, of the received power of the terminal devices 2-1, 2-2, the position (x ₁ , y ₁ ) of the terminal device 2-1 and the terminal device 2-2 on the side of the terminal device 2-2 having the larger received power. The position (x ₂ , y ₂ ) and w ₁ : w ₂ are externally divided to obtain an external division point (x _E , y _E ).

When x _E and y _E have negative values, they are not calculated by simple summation, so any two terminal devices are extracted from a plurality of terminal devices, and the two positions of the extracted two terminal devices are externally divided. The process of obtaining the external dividing points is executed for all two terminal devices, and the average value of the obtained plural external dividing points is estimated as the wave source position.

When the total number of terminal devices 2 is N, the average values x _{E_ave} and y _{E_ave} of the extra-division points are determined by the following equation.

In the equation (3), _{w i} is made i-th received power _{P i} of the terminal device 2, _{w j} consists received power _{P j} of the j-th terminal device 2.

  FIG. 8 is a diagram for explaining a method of determining which of the outer division point and the inner division point is used.

  With reference to FIG. 8, when the diameter of the observation area REG is D and the distance between the two terminal devices 2 is d, when d is equal to or larger than the radius (= D / 2) of the observation area, the wave source S is It exists between the two terminal devices 2. This is because the observation area REG has a circular shape centered on the wave source S as described above.

  On the other hand, when d is smaller than the radius (= D / 2), the wave source S exists at a position biased to one side of the two terminal devices 2.

  Therefore, when the distance d between the two terminal devices 2 is equal to or larger than the radius (= D / 2) of the observation area REG, the internally dividing point obtained by internally dividing the positions of the two terminal devices is estimated as the wave source position, and When the distance d between the terminal devices 2 is smaller than the radius (= D / 2) of the observation area REG, the external branch point obtained by externally dividing the positions of the two terminal devices is estimated as the wave source position.

  That is, the wave source position is estimated by the following equation.

_XEst and _yEst of Formula (4) show the estimated value of a wave source position. Further, x _th shown in Expression (4) is the radius of the observation area REG in the x axis direction, and y _th is the radius of the observation area REG in the y axis direction.

  FIG. 9 is a flow chart for explaining the operation of the wave source position estimating device 1 shown in FIG.

  With reference to FIG. 9, when the operation of the wave source position estimating apparatus 1 is started, the calculating unit 14 calculates the variance Var of the distribution of the plurality of terminal devices 2 (step S1) and estimates the calculated variance Var. Output to the means 15.

  Then, the estimating unit 15 receives the variance Var from the calculating unit 14, and determines whether the received variance Var is equal to or more than the threshold value Var_th (step S2).

When it is determined in step S2 that the variance Var is equal to or greater than the threshold value Var_th, the estimation unit 15 determines all position information (x _i , y _i ) read from the storage unit 13 and all received power P _i . based on, using equation (1), the reception power _{P i} a plurality of terminal devices 2 of the center of gravity is weighted by _(x G, _{y G)} were calculated (step S3), and the calculated center of gravity _(x G, y _G ) is estimated as the wave source position (step S4).

On the other hand, when it is determined in step S2 that the variance Var is not greater than or equal to the threshold value Var_th, the estimation unit 15 selects any two points from all the position information (x _i , y _i ) read from the storage unit 13. Is extracted to calculate the distance between the two points (step S5).

  Then, the estimation means 15 determines whether or not the distance between the two points is equal to or greater than a threshold value (= radius of the observation area) (step S6).

  When it is determined in step S6 that the distance between the two points is not greater than or equal to the threshold value (= radius of the observation area), the estimation unit 15 calculates the two extra-division points (step S7).

  On the other hand, when it is determined in step S6 that the distance between the two points is equal to or greater than the threshold value (= radius of the observation area), the estimating unit 15 calculates the internal division points of the two points (step S8).

  Then, after step S7 or step S8, the estimation means 15 determines whether or not the evaluation of all the measurement points has been completed (step S9).

  When it is determined in step S9 that the evaluation of all the measurement points has not been completed, the series of operations returns to step S5, and until it is determined in step S9 that the evaluation of all the measurement points is completed, Steps S5 to S9 described above are repeatedly executed.

  Then, when it is determined in step S9 that the evaluation of all the measurement points has been completed, the estimation means 15 calculates the average value of the interior division point and the exterior division point using the equation (4) (step S10). Then, the calculated average value is estimated as the wave source position (step S11).

  Then, after step S4 or step S11, the operation of estimating the wave source position ends.

  As described above, in the embodiment of the present invention, based on the position information and the reception power of the plurality of terminal devices, the center of gravity of the plurality of terminal devices or the two positions of the two terminal devices are weighted by the reception power. Since the average value of the equinoxes or the extranodal points is estimated as the wave source position, the wave source position can be estimated using four arithmetic operations. Therefore, it is possible to easily estimate the wave source position while suppressing the amount of calculation.

  Further, in the flowchart shown in FIG. 9, since the internal division point and the external division point are used properly, the wave source position can be accurately estimated even when the position of the terminal device is biased.

  In addition, in step S10 of FIG. 9, it has been described that the internal division point or the external division point is simply averaged to obtain the average value. The average value of the internal division point or the external division point may be obtained by weighting with the average power of the two received powers of the two terminal devices used for obtaining the equivalence point.

  That is, the average value of the inner dividing points may be obtained by the following equation (5), and the average value of the outer dividing points may be obtained by the equation (6).

  FIG. 10 is a flowchart for explaining another operation of the wave source position estimating device 1 shown in FIG.

  The flowchart shown in FIG. 10 is obtained by replacing steps S5 to S8 of the flowchart shown in FIG. 9 with steps S21 to S28, and is otherwise the same as the flowchart shown in FIG.

  When the operation of the wave source position estimating device 1 is started, steps S1 to S4 described above are sequentially executed.

Then, in step S2, when it is determined that the variance Var is smaller than the threshold value Var_th, the estimation unit 15 selects any 2 of the position information (x _i , y _i ) read from the storage unit 13. Points are extracted, and a distance Lx between two points in the x-axis direction and a distance Ly between two points in the y-axis direction are calculated (step S21).

  Then, the estimation unit 15 determines whether or not the distance Lx in the x-axis direction is equal to or greater than the threshold value L_th_x (step S22). The threshold value L_th_x is set to the radius of the observation area REG in the x-axis direction.

  When it is determined in step S22 that the distance Lx is not equal to or greater than the threshold value L_th_x, the estimation unit 15 further determines whether the distance Ly in the y-axis direction is equal to or greater than the threshold value L_th_y (step S23). The threshold L_th_y is set to the radius of the observation area REG in the y-axis direction.

  On the other hand, when it is determined in step S22 that the distance Lx is equal to or greater than the threshold value L_th_x, the estimating unit 15 further determines whether the distance Ly in the y-axis direction is equal to or greater than the threshold value L_th_y (step). S24).

  When it is determined in step S23 that the distance Ly is not equal to or greater than the threshold value L_th_y, the estimating unit 15 calculates the external dividing point between the two points in both the x-axis direction and the y-axis direction (step S25).

  On the other hand, when it is determined in step S23 that the distance Ly is equal to or greater than the threshold value L_th_y, the estimating unit 15 calculates the external dividing point between the two points in the x-axis direction and the two points in the y-axis direction. An internal division point between the points is calculated (step S26).

  When it is determined in step S24 that the distance Ly is not equal to or greater than the threshold value L_th_y, the estimation unit 15 calculates an internal division point between the two points in the x-axis direction and a distance between the two points in the y-axis direction. The external division point of is calculated (step S27).

  On the other hand, when it is determined in step S24 that the distance Ly is equal to or greater than the threshold value L_th_y, the estimating unit 15 calculates the internally dividing point between the two points in both the x-axis direction and the y-axis direction (step). S28).

  Then, after any of step S25 to step S28, the process proceeds to step S9, and in step S9, steps S21 to S28 and S9 described above are repeatedly executed until it is determined that the evaluation of all the measurement points is completed. It

  Then, when it is determined in step S9 that the evaluation of all the measurement points has been completed, the above-described steps S10 and S11 are sequentially executed. In this case, in step S10, the estimation unit 15 calculates the average values of the interior division point and the exterior division point in the x-axis direction and the y-axis direction, respectively.

  As described above, according to the flowchart shown in FIG. 10, either the internal division point or the external division point is separately used in the x-axis direction and the y-axis direction (see step S22 to step S28), and therefore the calculation is performed in step S10. The averaged value becomes closer to the source position.

  Therefore, the wave source position can be estimated more accurately.

  Also, in the flowchart shown in FIG. 10, since the internal division point and the external division point are used properly, the wave source position can be accurately estimated even if the position of the terminal device is biased.

  FIG. 11 is a schematic diagram showing another configuration of the wave source position estimating device 1 shown in FIG. In the embodiment of the present invention, wave source position estimating apparatus 1 may be wave source position estimating apparatus 1A shown in FIG.

  Referring to FIG. 11, a wave source position estimating device 1A is the same as the wave source position estimating device 1 except that an estimating means 16 and a detecting means 17 are added to the wave source position estimating device 1 shown in FIG. .

The estimation unit 16 reads a plurality of terminal information from the storage unit 13, and records a variation of the received power P _i with time based on a plurality of received power P _i and a plurality of time information included in the read plurality of terminal information. To do. Then, the estimating means 16 estimates which of the error factors the received power P _i is changing, such as noise and fading, based on the variation of the received power P _i with time, and the estimated error factor is detected. Output to 17.

The detection means 17 reads a plurality of received powers P _i from the storage means 13 and receives error factors from the estimation means 16. Then, the detection unit 17 detects the reception power P _{i_CFD} satisfying the required reliability from the plurality of reception powers P _i by the method described later, and outputs the detected reception power P _{i_CFD} to the estimation unit 15.

In addition, in the wave source position estimating device 1A, the estimating means 15 estimates the wave source position by the above-described method based on the received power P _{i_CFD} received from the detecting means 17.

FIG. 12 is a conceptual diagram showing the variation of the received power P _{i with} time. Referring to FIG. 12, in a propagation environment affected by fading, received power P _i fluctuates with time as shown by a curve k1.

Further, when the propagation environment is a propagation environment affected by noise, the reception power P _i fluctuates depending on time so as to be different from the curve k1.

The estimating means 16 holds a variation characteristic in which the variation of the received power P _i with time is associated with an error factor such as noise and fading. Then, the estimation unit 16 determines which variation characteristic the variation in the received power P _i read from the storage unit 13 with time matches or approximates, and detects an error factor corresponding to the matching or approximated variation characteristic. By doing so, an error factor in which the received power P _i changes with time is estimated.

  The distribution of errors such as noise and fading is one of normal distribution, Rice distribution and Rayleigh distribution. The normal distribution is an error distribution when the error factor is noise, and the Rice distribution and the Rayleigh distribution are error distributions when the error factor is fading. The Rayleigh distribution is a distribution of errors when the scattering is severe.

Therefore, in the embodiment of the present invention, the propagation environment of the radio wave is estimated, and in accordance with the estimated propagation environment, the distribution of error factors is determined to be a normal distribution, a Rice distribution, or a Rayleigh distribution, Received power P _{i — CFD} that satisfies the reliability corresponding to the determined distribution of error factors is detected.

  The estimating means 16 detects a variation in the received power with time based on the terminal information from the fixed terminal or the terminal information from the mobile terminal having the slowest moving speed, and based on the detected variation in the received power with time. , A propagation environment such as a fading propagation environment or a noisy propagation environment is estimated.

  Then, the estimating means 16 determines the distribution of the error factor to be any one of the normal distribution, the Rice distribution and the Rayleigh distribution according to the estimated propagation environment, and sends the determined distribution of the error factor to the detecting means 17. Output.

  FIG. 13 is a diagram showing the relationship between the error type and the required reliability rate. With reference to FIG. 13, when the error type is a normal distribution, the requested reliability rate is, for example, 0.95, and the distribution point α is a normal distribution point having a reliability rate of 0.95. When the error type is the Rice distribution, the requested reliability rate is, for example, 0.90, and the distribution point β is the Rice distribution point having the reliability rate of 0.90. When the error type is the Rayleigh distribution, the required reliability rate is, for example, 0.80, and the distribution point γ is the Rayleigh distribution point having the reliability rate of 0.80.

  The detecting means 17 holds a correspondence table TBL showing the correspondence between the error types and the requested reliability rates shown in FIG. Then, when the detecting means 17 receives the distribution of the error factors from the estimating means 16, the detecting means 17 refers to the correspondence table TBL to detect the reliability rate corresponding to the received distribution of the error factors.

After that, the detection unit 17 reads out a plurality of _pieces of terminal information, and detects the received power P _{i_CFD} that satisfies the requested reliability rate based on the read out _pieces of terminal information.

More specifically, the detection means 17 detects the reception power P _{i_CFD} by the following method. The detection means 17 extracts a plurality of reception powers having different times from the reception powers received from one terminal device 2. For example, the detection means 17 extracts 10 received powers at different times. Then, the detecting means 17 calculates Z by the following equation using 10 received powers at different times.

  In Expression (7), n is the size of the number of samples, e is the allowable error range, and Z is the distribution point with the reliability rate α. P is the ratio of the received power used for estimating the wave source position in the population. For example, when estimating the wave source position using 10 received powers out of 100 received powers, P = 0.1. N is the population.

  FIG. 14 is a diagram showing the relationship between the sample size n and the error range e. FIG. 14 shows the relationship between the sample size n and the error range e when the average received power is −100 dBm and the reliability α is 0.95.

  With reference to FIG. 14, the sample size n is, for example, 10, 20, 50, or 100. The error range e is set to, for example, 10% when the sample size n is 10, and is set to, for example, 7% when the sample size n is 20, and the sample size n is 50%. Is set to, for example, 5%, and when the sample size n is 100, it is set to, for example, 3%. In this way, the error range e is set to decrease as the sample size n increases.

  When the sample size n is 10, there is a true value in the range of −10 to −90 dBm with a probability of 95% (reliability rate α = 0.95). Further, when the sample size n is 100, there is a true value in the range of −103 to −97 dBm with a probability of 95% (reliability rate α = 0.95).

  The error range e is set so as to decrease as the sample size n increases. Therefore, when the sample size n increases, the error range e decreases and the accuracy improves.

  The distribution points of the reliability rate α and the allowable error range e are set according to the required accuracy. When the sample size n does not increase, the constraint on the reliability rate α or the error range e is reduced. This is because when the sample size n does not increase, if the reliability rate α is set high or the error range e is set narrow, the received power satisfying the reliability rate α or the error range e is lost, and the source position cannot be estimated. .

N is the total number of received powers P _i , n is 10 received powers at different times (the number of some received powers of the total received power P _i ), and e is shown in FIG. Since it is set as shown, it is known and P is also known. Therefore, the detection means 17 can calculate Z by the equation (7).

  Then, the detection means 17 determines whether or not the calculated Z satisfies the reliability rate. More specifically, the detecting means 17 determines that the received power is correct data when Z satisfies the reliability rate, and determines that the received power is incorrect data when Z does not satisfy the reliability rate.

  Here, whether or not Z satisfies the reliability rate is determined by whether or not Z falls within a range where the deviation is ± 0.05 in the normal distribution when the error distribution follows the normal distribution. When Z falls within the range of ± 0.05 in the normal distribution, it is determined that Z satisfies the reliability rate, and when Z does not fall within the range of ± 0.05 in the normal distribution, Z Is determined not to meet the reliability rate.

  When the detection means 17 determines that the received power is incorrect data, the detecting means 17 determines whether the received power is correct data for another received power by the method described above.

  Even when the error distribution is the Rice distribution or the Rayleigh distribution, the detecting unit 17 determines whether the received power is correct data, as in the case where the error distribution is the normal distribution.

  Further, the detection means 17 extracts a plurality of reception powers having the same time information from the plurality of reception powers received from different terminal devices, and for each of the extracted plurality of reception powers, by the method described above, It may be determined whether or not the received power is correct.

  FIG. 15 is a diagram showing a sample for determining whether or not the received power is correct data.

Referring to FIG. 15A, n (n is an integer satisfying 2 ≦ n <i) reception powers P _{1 to} P _n are received at different positions (x ₁ , y ₁ ). Power.

Referring to FIG. 15B, the n pieces of reception power P ′ _{1 to} P ′ _n are reception powers having different position information in the time information t ₁ .

When determining whether or not the received power is correct data using the _n received powers P _{1 to} P _n , the detection unit 17 determines that the distribution of the _n received powers P _{1 to} P _n is a normal distribution or a rice. Whether the distribution or the Rayleigh distribution is applicable is determined. Then, when it is determined that the detection unit 17 corresponds to the normal distribution, the detection unit 17 refers to the correspondence table TBL and detects the reliability rate of 0.95 corresponding to the normal distribution.

  After that, the detection means 17 calculates Z using the equation (7), and determines whether or not the calculated Z satisfies the reliability rate by the method described above.

Even when the distribution of the _n received powers P _{1 to} P _n is the Rice distribution or the Rayleigh distribution, the detection unit 17 similarly determines whether or not the calculated Z satisfies the reliability rate by the method described above. .

Then, when the detecting means 17 determines that Z satisfies the reliability, that is, when the n received powers P _{1 to} P _n are correct data, reception at the position (x ₁ , y ₁ ) is performed. The electric power is detected as data for estimating the position of the wave source.

As described above, the estimation means 15 estimates the wave source position by using a plurality of received powers detected at different positions, so that the n received powers P ₁ detected at the same position (x ₁ , y ₁ ). This is because _Pn cannot be used as the received power for estimating the wave source position.

When determining whether or not the received power is correct data using the _n received powers P ′ _{1 to} P ′ _n , the detection unit 17 determines that the distribution of the _n received powers P ′ _{1 to} P ′ _n is It is determined whether the distribution is a normal distribution, a Rice distribution, or a Rayleigh distribution. Then, when it is determined that the detection unit 17 corresponds to the normal distribution, the detection unit 17 refers to the correspondence table TBL and detects the reliability rate of 0.95 corresponding to the normal distribution.

  After that, the detection means 17 calculates Z using the equation (7), and determines whether or not the calculated Z satisfies the reliability rate by the method described above.

Even when the distribution of the _n received powers P ′ _{1 to} P ′ _n is the Rice distribution or the Rayleigh distribution, the detecting means 17 similarly determines whether or not the calculated Z satisfies the reliability rate by the method described above. judge.

The detection means 17, when it is determined that Z satisfies the trust rate, i.e., when the n number of received power P _'1 to P' _n is determined to be correct data, the n received power P _'1 ˜P ′ _n is detected as data for estimating the position of the wave source.

This is because the n received powers P ′ _{1 to} P ′ _n are received powers detected at different positions, and thus can be used as data for estimating the wave source position in the estimating means 15 if the reliability is satisfied.

Therefore, the detecting means 17 detects the n received powers P ′ _{1 to} P ′ _n as a correct set of data.

On the other hand, when the detection means 17 determines that the n received powers P ′ _{1 to} P ′ _n are not correct data, another n different at least one of the _n received powers P ′ _{1 to} P ′ _n is different. The individual received powers are extracted, and it is determined by the above-described method whether or not the extracted other n received powers are correct data.

  The detection of the received power satisfying the required reliability by the above-mentioned method corresponds to the detection of the received power satisfying the required reliability according to the radio wave propagation environment. The estimating unit 16 estimates the propagation environment of the radio wave, and determines the distribution of the error factor according to the estimated propagation environment, and the detecting unit 17 determines the reliability rate (requested) corresponding to the determined distribution of the error factor. This is because the received power that satisfies the above (reliability rate) is detected.

  FIG. 16 is a flowchart for explaining the operation of the wave source position estimating device 1A shown in FIG.

  Referring to FIG. 16, when the operation of the wave source position estimating device 1A is started, the estimating means 16 estimates the distribution of the error by the above-mentioned method (step S31), and the estimated error distribution is detected by the detecting means. Output to 17.

  The detection unit 17 receives the error distribution from the estimation unit 16 and reads the plurality of terminal information from the storage unit 13. That is, the detection means 17 acquires the terminal information from the terminal device (step S32). Then, the detecting means 17 calculates Z based on the terminal information by the method described above, and determines whether or not the calculated Z satisfies the reliability rate (step S33).

  When it is determined in step S33 that Z does not satisfy the reliability rate, the series of operations returns to step S32, and steps S32 and S33 are repeatedly executed until it is determined in step S33 that Z satisfies the reliability rate. To do.

  Then, in step S33, when it is determined that Z satisfies the reliability rate, the detection means 17 outputs the received power where Z satisfies the reliability rate to the estimation means 15.

  The estimating means 15 receives the received power satisfying the reliability rate of Z from the detecting means 17, and estimates the wave source position based on the received power of the received Z satisfying the reliability rate according to the flowchart shown in FIG. 9 or 10. Step S34). As a result, the operation of the wave source position estimating device 1A ends.

  As described above, the wave source position estimating apparatus 1A estimates the wave source position by using the received power that satisfies the required reliability among the received powers received from the terminal device 2, so that there are error factors such as noise and fading. Even in the environment, the wave source position can be accurately estimated.

  The estimation of the wave source position in the wave source position estimating devices 1 and 1A may be executed by software.

  In this case, each of the wave source position estimation devices 1 and 1A includes a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory).

  The ROM includes any of the program Prog_A including the flowchart shown in FIG. 9, the program Prog_B including the flowchart illustrated in FIG. 10, the program Prog_C including the flowchart illustrated in FIGS. 9 and 15, and the program Prog_D including the flowchart illustrated in FIGS. Stores or.

  Then, the CPU reads one of the programs Prog_A to Prog_D from the ROM and executes the read program (one of the programs Prog_A to Prog_D) to estimate the wave source position.

  In this case, the RAM is used for storing the terminal information received from the terminal device 2 and for various calculations.

  Further, any of the programs Prog_A to Prog_D may be recorded in a recording medium such as a CD or a DVD and distributed. In this case, the CPU reads the program (one of the programs Prog_A to Prog_D) from the mounted recording medium and executes it to estimate the wave source position. Therefore, a recording medium such as a CD or a DVD in which the program (one of the programs Prog_A to Prog_D) is recorded is a recording medium readable by a computer (CPU).

  In the above, the wave source position estimation devices 1 and 1A have been described. That is, a case where the wave source position is estimated using the received power received from the terminal device 2 as it is, and a case where the wave source position is estimated using the received power satisfying the required reliability rate out of the received power received from the terminal device 2. And explained.

  Therefore, the wave source position estimating apparatus according to the embodiment of the present invention includes a receiving unit that receives terminal information including the position information of the terminal apparatus including the mobile terminal or the stationary terminal and the received power at the terminal apparatus from a plurality of terminal apparatuses, Calculation means for calculating a variance in the distribution of the positions of the plurality of terminal devices based on a plurality of position information included in the plurality of terminal information of the plurality of terminal devices, and the calculated variance is equal to or more than a first threshold value. At this time, the center of gravity of the plurality of terminal devices weighted by the received power based on the plurality of position information and the plurality of received powers included in the plurality of terminal information is estimated as the wave source position, and the calculated dispersion is the first distribution. When it is smaller than the threshold value, an external division point that externally divides two positions indicated by the positional information of two terminal devices of the plurality of terminal devices or an internal division point that internally divides the two positions is obtained. And an estimation unit that estimates the position obtained by averaging the obtained external and internal division points as the wave source position. Just do it.

  Further, the program to be executed by the computer according to the embodiment of the present invention is a program for causing the computer to execute estimation of the wave source position, and the receiving means is position information of the terminal device including a mobile terminal or a stationary terminal. And a first step of receiving terminal information including a received power at the terminal device from the plurality of terminal devices, and a calculating unit based on a plurality of position information included in the plurality of terminal information of the plurality of terminal devices. A second step of calculating the variance in the distribution of the positions of the terminal devices, and the estimating means, when the calculated variance is equal to or more than a first threshold value, a plurality of pieces of position information and a plurality of pieces of information included in the plurality of terminal information. The center of gravity of the plurality of terminal devices weighted by the received power based on the received power of is estimated as the wave source position, and the calculated variance is greater than the first threshold value. At the same time, a process for obtaining an external division point that externally divides two positions or an internal division point that internally divides two positions indicated by the position information of two terminal apparatuses of the plurality of terminal apparatuses is performed. A third step of executing the operation on all two of the terminal devices and estimating the position obtained by averaging the obtained external or internal points as the wave source position Good.

  The embodiments disclosed this time are to be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the claims, and is intended to include meanings equivalent to the claims and all modifications within the scope.

  The present invention is applied to a wave source position estimating device, a program to be executed by a computer, and a computer-readable recording medium recording the program.

  1, 1A wave source position estimating device, 2 terminal device, 10 wireless communication system, 11 antenna, 12 receiving means, 13 storing means, 14 calculating means, 15, 16 estimating means, 17 detecting means.

Claims (11)

Receiving means for receiving terminal information from a plurality of terminal devices including position information of the terminal device composed of a mobile terminal or a stationary terminal and received power when the terminal device receives a radio wave from a wave source ,
Calculation means for calculating the variance in the distribution of the positions of the plurality of terminal devices based on a plurality of position information included in a plurality of terminal information of the plurality of terminal devices,
When the calculated dispersion is equal to or more than a first threshold value, the plurality of terminals weighted by the reception power based on the plurality of position information and a plurality of reception power included in the plurality of terminal information. The center of gravity of the device is estimated as the wave source position, and when the calculated dispersion is smaller than the first threshold value, two positions indicated by position information of two terminal devices of the plurality of terminal devices are determined. The process of obtaining an external division point for external division or an internal division point for internally dividing the two positions is executed for all two terminal devices of the plurality of terminal devices, and the obtained external division point or internal division point is obtained. And an estimation means for estimating a position obtained by averaging the positions as the wave source position.   The estimating means averages the internal division points when the calculated variance is smaller than the first threshold and the distance between the two positions is equal to or larger than a second threshold. When the calculated position is estimated as the wave source position, the calculated dispersion is smaller than the first threshold value, and the distance between the two positions is smaller than the second threshold value. The wave source position estimating device according to claim 1, wherein a position obtained by averaging the outer branch points is estimated as the wave source position.   The wave source position estimating device according to claim 2, wherein the estimating unit estimates a position obtained by simply averaging the outer dividing point or the inner dividing point as the wave source position.   The estimation unit estimates the position obtained by weighting and averaging the outer division point or the inner division point with an average power of two reception powers of the two terminal devices as the wave source position. Wave source position estimation device. Out of the plurality of received power, further comprising a detection means for detecting the received power satisfying the reliability required according to the radio wave propagation environment,
The wave source position estimating device according to claim 1, wherein the estimating unit estimates the wave source position using the received power detected by the detecting unit. A program for causing a computer to estimate the source position,
A first step in which the receiving means receives, from a plurality of terminal devices, terminal information including position information of the terminal device composed of a mobile terminal or a stationary terminal and received power when the terminal device receives a radio wave from a wave source ;
A second step in which the calculating means calculates the variance in the distribution of the positions of the plurality of terminal devices based on a plurality of position information included in the plurality of terminal information of the plurality of terminal devices;
When the calculated variance is equal to or larger than a first threshold value, the estimating means is weighted by the received power based on the received powers included in the plurality of position information and the plurality of terminal information. The center of gravity of the plurality of terminal devices is estimated as a wave source position, and when the calculated dispersion is smaller than the first threshold value, it is indicated by position information of two terminal devices of the plurality of terminal devices. The process of obtaining an external dividing point that internally divides two positions or an internal dividing point that internally divides the two positions is executed for all two terminal devices of the plurality of terminal devices, and the obtained external dividing points Alternatively, a program for causing a computer to execute a third step of estimating a position obtained by averaging the internally dividing points as the wave source position.   In the third step, when the calculated variance is smaller than the first threshold value and the distance between the two positions is equal to or larger than a second threshold value, A position obtained by averaging the internal division points is estimated as the wave source position, the calculated dispersion is smaller than the first threshold, and the distance between the two positions is the second. The program for causing a computer to execute according to claim 6, which estimates a position obtained by averaging the external dividing points as the wave source position when the value is smaller than a threshold value.   8. The computer according to claim 7, wherein, in the third step, the estimating means estimates a position obtained by simply averaging the outer dividing point or the inner dividing point as the wave source position. program.   In the third step, the estimating means estimates a position obtained by weighting and averaging the outer division point or the inner division point with an average power of two reception powers of the two terminal devices as the wave source position. A program to be executed by the computer according to claim 7. The detecting means further causes the computer to execute a fourth step of detecting, from the plurality of received powers, received powers satisfying a reliability rate required according to a radio wave propagation environment,
10. The computer according to claim 6, wherein in the third step, the estimating means estimates the wave source position by using the received power detected in the fourth step. A program to run.   A computer-readable recording medium in which the program according to any one of claims 6 to 10 is recorded.

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