JP2019132850A - program - Google Patents

Abstract

Provided is an estimating apparatus and the like that can estimate a direction in which a moving object exists using a radio signal in a short time and with high accuracy. A reception signal received by each of a plurality of reception antenna elements, which is transmitted from one transmission antenna element and includes a reflection signal reflected by a moving object, is observed for a first period. A complex transfer function for calculating a complex transfer function representing a propagation characteristic between one transmitting antenna element and each of the plurality of receiving antenna elements from the receiving unit and each of the plurality of received signals observed in the first period; A calculation unit configured to calculate two or more pieces of difference information, which is a difference information indicating a difference between two complex transfer functions at two time points at a predetermined interval among a plurality of calculated complex transfer functions and is represented by an N-dimensional vector; And a direction estimation processing unit 16 for estimating a direction in which a moving object is present, using the estimation device 10 as a direction reference, using the difference information calculated by the two or more. And. [Selection diagram] Fig. 1

Description

  The present invention relates to a program for executing an estimation method for estimating the direction and position of a moving object using a radio signal.

  As a method for knowing the position of a person or the like, a method using a wireless signal has been studied (for example, see Patent Documents 1 to 3). Patent Document 1 discloses a living body detection method using a Doppler sensor, and Patent Document 2 discloses a human action and biological information detection method using a Doppler sensor and a filter. Patent Document 3 discloses that the position and state of a person to be detected can be known by analyzing a component including a Doppler shift using Fourier transform.

Special table 2014-512526 gazette International Publication No. 2014/141519 Japanese Patent Laying-Open No. 2015-117972 JP2015-072173 A JP2015-119770A International Publication No. 2012/125100 JP, 2014-215200, A Japanese Patent Laying-Open No. 2015-117916 International Publication No. 2012/115220

F. Adib, Z. Kabelac, D. Katabi, and R. Miller, “3D trackingvia body radio reflections”, 11th USENIX Symp. Net. Systems Design \ & Impl. (USENIX NSDI'14), Apr. 2014. Dai Sasakawa, Keita Konno, Naoki Honma, Kentaro Nishimori, Nobuyasu Takemura, Tsutomu Mitsui, “Fast Estimation Algorithm for Living Body Radar,” 2014 International Symposium on Antennas and Propagation (ISAP 2014), FR3D, pp.583-584, Dec. 2014

  However, the methods of Patent Documents 1 and 2 have a problem that the presence or absence of a person can be detected, but the direction and position where the person exists cannot be detected.

  Further, the method of Patent Document 3 has a problem that it is difficult to detect the direction in which a living body such as a person exists and the position where the living body exists in a short time with high accuracy. This is because the frequency change due to the Doppler effect derived from biological activity is extremely small, and in order to observe this frequency change by Fourier transform, it is essential to observe for a long time (for example, several tens of seconds) while the living body is stationary. In general, the living body does not continue the same posture or position for several tens of seconds.

  The present invention has been made in view of the above-described circumstances, and a program for executing an estimation method capable of performing estimation of a direction in which a moving object exists using a radio signal in a short time with high accuracy. The purpose is to provide.

  In order to achieve the above object, a program according to an aspect of the present invention is a received signal received by each of N reception antenna elements to a computer, transmitted from one transmission antenna element, Among the received signals including the reflected signal reflected by the first object, the received signals observed for the first period corresponding to the period derived from the activity of the moving object are acquired, and the plurality of received signals observed in the first period A plurality of complex transfer functions representing propagation characteristics between the transmitting antenna element and each of the N receiving antenna elements, and (i) calculating the plurality of complex transfer functions to the plurality of received signals. Is sequentially recorded in a time series in the order in which they are observed. (Ii) Among the plurality of complex transfer functions, differential information indicating the difference between two complex transfer functions at two points in time at a predetermined interval, 2 or more of the difference information expressed by the vector of the vector is calculated, and the direction in which the moving object exists is estimated using the difference information calculated by the two or more as a reference of a device having at least the N reception antenna elements. To execute the process.

In order to achieve the above object, an estimation apparatus according to an aspect of the present invention is an estimation apparatus that estimates a position where a moving object exists, and includes M (M is a natural number of 2 or more) transmission antenna elements. A reception antenna unit including a transmission antenna unit, a reception antenna unit including N (N is a natural number of 2 or more) reception antenna elements, and a reception signal received by each of the N reception antenna elements. A reception unit for observing a reception signal transmitted from each of the transmission antenna elements and including a reflection signal reflected by a moving object for a first period corresponding to a period derived from the activity of the moving object; and observed in the first period Complex transfer function calculation for calculating a plurality of complex transfer functions representing propagation characteristics between each of the M transmit antenna elements and each of the N receive antenna elements from the plurality of received signals. When a plurality of the complex transfer function calculated (i),
(Ii) differential information indicating a difference between two complex transfer functions at two points in time of a predetermined interval among the plurality of complex transfer functions. A difference information calculation unit that calculates two or more difference information expressed by an M × N-dimensional matrix, and a position estimation processing unit that estimates the position where the moving object exists using the two or more difference information. Prepare.

  According to the present invention, it is possible to estimate the direction in which a moving object exists using a radio signal in a short time and with high accuracy.

FIG. 1 is a block diagram illustrating an example of a configuration of an estimation apparatus according to Embodiment 1. FIG. 2 is a diagram illustrating an example of a detection target of the estimation apparatus illustrated in FIG. FIG. 3 is a diagram conceptually showing a state of signal wave transmission in the antenna section shown in FIG. FIG. 4 is a conceptual diagram showing an example of two time points of a predetermined interval used when calculating difference information in the first embodiment. FIG. 5 is a conceptual diagram showing an example of two time points at a predetermined interval different from FIG. FIG. 6 is a flowchart showing an estimation process of the estimation device according to the first embodiment. FIG. 7 is a block diagram illustrating an example of a configuration of the estimation device according to the second embodiment. FIG. 8 is a diagram illustrating an example of a detection target of the estimation apparatus illustrated in FIG. FIG. 9 is a flowchart illustrating an estimation process of the estimation device according to the second embodiment. FIG. 10 is a diagram illustrating a concept of an experiment using the estimation method according to the second embodiment. FIG. 11 is a diagram illustrating an experimental result using the estimation method according to the second embodiment. FIG. 12 is a diagram illustrating another experimental result using the estimation method according to the second embodiment.

(Knowledge that became the basis of the present invention)
As a method for knowing the position of a person or the like, a method using a radio signal is being studied.

  For example, Patent Document 1 discloses a living body detection method using a Doppler sensor, and Patent Document 2 discloses a human action and biological information detection method using a Doppler sensor and a filter.

  Further, for example, Patent Document 3 discloses that a wireless signal is transmitted to a predetermined region, a wireless signal reflected by a detection target is received by a plurality of antennas, and a complex transfer function between transmitting and receiving antennas is estimated. Yes. The complex transfer function is a complex function representing the relationship between the input and the output, and here represents the propagation characteristic between the transmitting and receiving antennas. The number of elements of this complex transfer function is equal to the product of the number of transmitting antennas and the number of receiving antennas.

  Patent Document 3 further discloses that the position and state of a person to be detected can be known by analyzing a component including a Doppler shift using Fourier transform. More specifically, the time change of the complex transfer function element is recorded, and the time waveform is Fourier transformed. A biological activity such as breathing or heartbeat gives a slight Doppler effect to a reflected wave. Therefore, the component including the Doppler shift includes a human influence. On the other hand, the component without Doppler shift is not affected by a person, that is, corresponds to a reflected wave from a fixed object or a direct wave between transmitting and receiving antennas. From the above, Patent Document 3 discloses that the position and state of a person to be detected can be known by analyzing a component including a Doppler shift.

  Similarly, for example, in Patent Documents 4 to 9, a Doppler component derived from a person (living body) is extracted by performing Fourier transform on the observed signal. And it is disclosed that the state of the living body and the state of the living body such as heartbeat and respiration are detected by analyzing this.

  Further, for example, Non-Patent Document 1 discloses a method for detecting a human body direction and position without performing Fourier transform. In Non-Patent Document 1, a propagation response in an unmanned state is measured in advance, and a person position is estimated by analyzing a difference component assuming that a difference between the unmanned state and a manned state is caused by a person. More specifically, the position estimation method disclosed in Non-Patent Document 1 observes a frequency response of a wide band of 1 GHz or more, and calculates the propagation time of the extracted reflected wave derived from a person, so that different locations The distance from a plurality of antennas placed on is estimated, and the person position is estimated using the estimated distance. In Non-Patent Document 1, the time response of a complex propagation channel when manned is observed, and the reflection component from a fixed object such as a wall or a fixture is removed by subtracting the complex propagation channels at different times. Extract only reflected waves.

  Further, for example, Non-Patent Document 2 and Patent Document 6 disclose a method for estimating the direction of a living body by removing unnecessary components from a complex transfer function when manned. More specifically, in order to remove the reflected wave from the fixed object and the direct wave between the transmitting and receiving antennas from the complex transfer function, the complex transfer function at the time of unattended is measured in advance. And since the complex transfer function during manned includes reflected waves from fixed objects and direct waves between transmitting and receiving antennas, unnecessary components are removed by subtracting the complex transfer function during unmanned from the complex transfer function during manned To do.

  However, in the methods of Patent Documents 1 and 2 described above, the presence or absence of a person can be detected, but the direction and position where the person exists cannot be detected.

  Further, in the method of Patent Document 3 described above, an observation time of several tens of seconds is required to perform Fourier transform. Therefore, it is difficult to detect the direction and position of a person in a short time with high accuracy. This is because the frequency change due to the Doppler effect derived from biological activity is extremely small, and in order to observe this frequency change by Fourier transform, it is essential to observe for a long time (for example, several tens of seconds) while the living body is stationary. In general, since the living body does not continue the same posture or position for several tens of seconds, if the observation time is shortened, the signal derived from the living body cannot be correctly extracted by Fourier transform, and the estimation accuracy of the direction and position of the person is improved. descend.

  This problem, that is, the problem of Patent Document 3 described above, can also occur in the inventions disclosed in Patent Documents 4 to 9.

  In addition, the methods of Patent Document 6 and Non-Patent Documents 1 and 2 have a problem that it is necessary to measure in advance the complex transfer function during unattended. This is because the position of a person cannot be estimated if a change occurs in the propagation environment itself, such as when furniture such as furniture moves. Considering application to an environment in which a person lives, it is assumed that chairs, desks, and the like move frequently. Therefore, the methods of Patent Document 6 and Non-Patent Documents 1 and 2 described above are applied to the living environment of a person. It is difficult.

  As described above, the conventional technique has a problem that it is not possible to estimate the direction in which a moving object exists using a radio signal in a short time with high accuracy.

  In recent years, a radar that estimates the presence direction of a living body in a radio wave propagation environment in which multiple waves are present has been studied using the feature that a living body causes a Doppler shift in radio waves due to some biological activity such as breathing and heartbeat. Has been. That is, a radar that estimates a living body direction by irradiating a living body with radio waves, removing a signal component that does not pass through the living body by Fourier transform of a received signal, and estimating an arrival direction of a radio wave reflected from the living body has been studied.

  However, as described above, the biological direction cannot be estimated in a short time and with high accuracy using Fourier transform.

  In view of this, the inventors have come up with an estimation device and the like that can perform estimation of a direction in which a moving object is present using radio signals in a short time with high accuracy.

That is, the estimation apparatus according to an aspect of the present invention is an estimation apparatus that estimates a direction in which a moving object exists, and includes one transmission antenna element and N reception antenna elements (N is a natural number of 2 or more). A reception signal received by each of the antenna unit and each of the N reception antenna elements, including a reflection signal transmitted from the transmission antenna element and reflected by the moving object, is derived from the activity of the moving object. A propagation characteristic between the transmitting antenna element and each of the N receiving antenna elements from a receiving unit that observes a first period corresponding to a period to be transmitted, and a plurality of the received signals observed in the first period A complex transfer function calculating unit that calculates a plurality of complex transfer functions that represent: and (i) sequentially recording the calculated plurality of complex transfer functions in a time series in which the plurality of received signals are observed And (ii) difference information indicating a difference between two complex transfer functions at two points in time at a predetermined interval among the plurality of complex transfer functions and calculating two or more difference information expressed by an N-dimensional vector An information calculation unit; and a direction estimation processing unit that estimates the direction in which the moving object exists using the estimation apparatus as a reference for the direction using the difference information calculated two or more.

  With this configuration, it is possible to estimate the direction in which the moving object exists with high accuracy from a short observation time corresponding to the period derived from the activity of the moving object. Thereby, it is possible to estimate the direction in which the moving object is present using a radio signal in a short time and with high accuracy.

  Here, for example, the start point of two time points of the predetermined interval in each of the two or more pieces of difference information is a different time.

  Thereby, since the influence of an instantaneous noise can be weakened by acquiring the average of 2 or more difference information, the precision of direction estimation can be improved more.

  For example, the moving object may be a living body.

  Further, for example, the period may be a period derived from a living body including at least one of respiration, heartbeat, and body movement of the living body, and the predetermined interval may be substantially half of the period derived from the living body.

  This makes it possible to estimate the direction in which the living body exists from observation in a first period corresponding to at least one cycle of breathing, heartbeat, and body movement.

  In addition, for example, the direction estimation processing unit calculates and calculates an instantaneous correlation matrix that is a correlation matrix of a difference time that is two time points of a predetermined interval in the difference information from each of the two or more calculated difference information. The instantaneous correlation matrix may be used to estimate the arrival direction of the reflected signal by a predetermined arrival direction estimation method, and the direction in which the moving object exists may be estimated based on the estimated arrival direction of the reflected signal. .

  Here, for example, the predetermined direction-of-arrival estimation method is an estimation method based on a MUSIC (MUltiple SIgnal Classification) algorithm.

An estimation apparatus according to an aspect of the present invention is an estimation apparatus that estimates a position where a moving object exists, and includes a transmission antenna unit including M (M is a natural number of 2 or more) transmission antenna elements, and N (N is a natural number greater than or equal to 2) receiving antenna units and received signals received by each of the N receiving antenna elements and transmitted from each of the M transmitting antenna elements. A receiving unit for observing a received signal including a reflected signal reflected by a moving object for a first period corresponding to a period derived from the activity of the moving object, and a plurality of the received signals observed in the first period, A complex transfer function calculator for calculating a plurality of complex transfer functions representing propagation characteristics between each of the M transmit antenna elements and each of the N receive antenna elements; and (i) a plurality of calculated previous A complex transfer function is sequentially recorded in a time series that is the order in which the plurality of received signals are observed, and (ii) a difference between two complex transfer functions at two time points at a predetermined interval among the plurality of complex transfer functions. A difference information calculation unit that calculates two or more difference information expressed by an M × N-dimensional matrix, and a position estimation that estimates a position where the moving object exists using the two or more difference information A processing unit.

  With this configuration, it is possible to estimate the position where the moving object exists with high accuracy by a short observation time corresponding to the period derived from the activity of the moving object. Accordingly, it is possible to estimate the position where the moving object is present using a radio signal in a short time and with high accuracy.

  Here, for example, the start point of two time points of the predetermined interval in each of the two or more pieces of difference information is a different time.

  Thereby, since the influence of instantaneous noise can be weakened by acquiring the average of two or more difference information, the precision of position estimation can be improved more.

  For example, the moving object may be a living body.

  For example, the period may be a period derived from a living body including at least one of respiration, heartbeat, and body motion of the living body, and the predetermined interval may be substantially half of the period derived from the living body.

  Thereby, since the average of two or more difference information is acquirable, the precision of position estimation can be improved more by weakening the influence of instantaneous noise.

  Further, for example, the position estimation processing unit calculates and calculates an instantaneous correlation matrix that is a correlation matrix of a difference time that is two time points of a predetermined interval in the difference information from each of the two or more calculated difference information. Using the instantaneous correlation matrix, the transmission direction of the transmission signal transmitted from the transmission antenna unit to the moving body and the arrival direction of the reflected signal are estimated by a predetermined arrival direction estimation method, and the transmission signal The position where the moving object exists may be estimated based on the transmission direction and the arrival direction of the reflected signal.

  Here, for example, the predetermined arrival direction estimation method is an estimation method based on the MUSIC algorithm.

  The present invention is not only realized as an apparatus, but also realized as an integrated circuit including processing means included in such an apparatus, or realized as a method using the processing means constituting the apparatus as a step. Can be realized as a program for causing a computer to execute, or as information, data, or a signal indicating the program. These programs, information, data, and signals may be distributed via a recording medium such as a CD-ROM or a communication medium such as the Internet.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Each of the embodiments described below shows a preferred specific example of the present invention. The numerical values, shapes, materials, constituent elements, arrangement positions and connecting forms of the constituent elements, steps, order of steps, and the like shown in the following embodiments are merely examples, and are not intended to limit the present invention. In addition, among the constituent elements in the following embodiments, constituent elements that are not described in the independent claims indicating the highest concept of the present invention are described as optional constituent elements that constitute a more preferable embodiment. In addition, in this specification and drawing, about the component which has the substantially same function structure, duplication description is abbreviate | omitted by attaching | subjecting the same code | symbol.

(Embodiment 1)
In the following, referring to the drawings, the estimation apparatus 10 according to the first embodiment uses the difference information of the complex transfer function observed at two points in time that are different from each other for a predetermined period to determine the direction of the moving object (living body) that is the detection target. Will be described.

[Configuration of Estimation Device 10]
FIG. 1 is a block diagram illustrating an example of the configuration of the estimation apparatus 10 according to the first embodiment. FIG. 2 is a diagram illustrating an example of a detection target of the estimation apparatus 10 illustrated in FIG.

  An estimation apparatus 10 shown in FIG. 1 includes an antenna unit 11, a transmitter 12, a reception unit 13, a complex transfer function calculation unit 14, a difference information calculation unit 15, and a direction estimation processing unit 16, and includes a moving object. Estimate the existing direction.

[Transmitter 12]
The transmitter 12 generates a high frequency signal used for estimating the direction of the living body 50. For example, as illustrated in FIG. 2, the transmitter 12 transmits the generated signal (transmission wave) from one transmission antenna element included in the antenna unit 11.

[Antenna unit 11]
The antenna unit 11 includes one transmission antenna element and N reception antenna elements (N is a natural number of 2 or more). In this embodiment, the antenna unit 11 is composed of a receiving antenna unit 11B and the transmitting antenna unit 11A, the transmitting antenna unit 11A, the transmitting antenna elements and M _R receive antennas elements (receiving a transmitting antenna 1 element Array antenna).

As described above, one transmission antenna element transmits a signal (transmission wave) generated by the transmitter 12. For example, as shown in FIG. 2, each of the M _R receive antennas elements, is transmitted from the one transmit antenna elements, to receive a reflected signal (received signal) by the body 50.

[Receiver 13]
The receiving unit 13 receives a reception signal received by each of the N reception antenna elements, including a reflection signal transmitted from the transmission antenna element and reflected by the moving object, from a period derived from the activity of the moving object. The first period corresponding to is observed. Here, the moving body is a living body 50 as shown in FIG. The period derived from the activity of the moving body is a period derived from the living body (biological variation period) including at least one of respiration, heartbeat, and body movement of the living body 50.

In this embodiment, the receiving unit 13, N pieces (M _R number) receivers (receivers 13-1 receiver 1
3-N). Each of the receivers 13-1 to 13-N converts a high-frequency signal received by a corresponding receiving antenna element into a low-frequency signal that can be processed. The reception unit 13 transmits the low-frequency signal converted by each of the receivers 13-1 to 13 -N to the complex transfer function calculation unit 14 at least in the first period.

[Complex transfer function calculator 14]
The complex transfer function calculation unit 14 calculates a plurality of complex transfer functions representing the propagation characteristics between the transmission antenna element and each of the N reception antenna elements from the plurality of reception signals observed in the first period.

Complex in the present embodiment, the complex transfer function calculation unit 14, representing the propagation characteristics between the low frequency signal transmitted from the receiving unit 13, and one transmit antenna elements and M _R receive antennas elements Calculate the transfer function. Hereinafter, a more specific description will be given with reference to FIG.

FIG. 3 is a diagram conceptually showing a state of signal wave transmission in the antenna unit 11 shown in FIG. As shown in FIG. 3, the transmission wave transmitted from the transmission antenna element of the transmission antenna unit 11A is reflected by the living body 50 and reaches the reception array antenna of the reception antenna unit 11B. Here, the receiving array antenna consists M _R receive antennas elements, a linear array of element spacing d. Further, θ is the direction of the living body 50 viewed from the front of the receiving array antenna. The distance between the living body 50 and the receiving array antenna is sufficiently large, and the reflected wave derived from the living body arriving at the receiving array antenna can be regarded as a plane wave.

  In this case, the complex transfer function calculation unit 14 uses the complex received signal vector observed using the receiving array antenna.

から、送信アンテナ素子と受信アレーアンテナとの間の伝搬特性を表す複素伝達関数ベクトルを算出することができる。複素伝達関数ベクトルは、例えば、

により算出できる。ここで、sは複素送信信号であり、既知であるものとする。

From this, it is possible to calculate a complex transfer function vector representing the propagation characteristics between the transmitting antenna element and the receiving array antenna. The complex transfer function vector is, for example,

Can be calculated. Here, s is a complex transmission signal, and is known.

[Difference information calculation unit 15]
The difference information calculation unit 15 sequentially records the calculated plurality of complex transfer functions in a time series that is the order in which the plurality of received signals are observed. Then, the difference information calculation unit 15 is a difference information indicating a difference between two complex transfer functions at two points in time of a predetermined interval among the plurality of complex transfer functions, and the difference information expressed by an N-dimensional vector is 2 Calculate as above. Here, the start point of two time points of a predetermined interval in each of the two or more pieces of difference information is a different time. Further, the predetermined interval may be approximately half of the cycle derived from the living body 50 (biological variation cycle).

FIG. 4 is a conceptual diagram showing an example of two time points of a predetermined interval used when calculating difference information in the first embodiment. FIG. 5 is a conceptual diagram showing an example of two time points at a predetermined interval different from FIG. In FIG. 4, the vertical axis represents the variable channel value, and the horizontal axis represents time. T _meas represents the observation time of the received signal. This observation time T _meas is the first period described above. The observation time T _meas corresponds to, for example, the maximum period of biological fluctuation including at least one of respiration, heartbeat, and body movement of a living body, that is, the maximum period derived from biological fluctuation. In the example shown in FIG. 4, the observation time is about 3 seconds corresponding to the period of the respiratory activity of the living body 50.

When a plurality of complex transfer functions calculated from reception signals observed by the receiving unit 13, that is, time-varying channels are sequentially recorded at the observation time T _meas as shown in FIG. 4, the observation time T _meas corresponds to the maximum period of biological fluctuation. Therefore, the observation time T _meas always includes the maximum value and the minimum value of the fluctuation of the living body 50. Here, if the maximum period of biological fluctuation is T _max and the minimum period derived from biological fluctuation (minimum period of biological fluctuation) is T _min , the time difference between these half periods, T _max / 2 and T _min / 2, is The time difference corresponds to the fluctuation of the living body 50. Therefore, the predetermined interval T when calculating the difference information of the complex transfer function can be in the range of T _max / 2 ≦ T ≦ T _min / 2. Thus, the predetermined interval T is set to the living body 5.
Even when it is approximately half of the cycle derived from 0 (biological variation cycle), the biological component can be extracted from the time-varying channel for one cycle of the living body 50.

In the example illustrated in FIG. 4, the difference information calculation unit 15 calculates, for example, difference information indicating a difference between the complex transfer functions at two points in time at different times of time t and time t + T, that is, at a predetermined interval T. . Then, the difference information calculation unit 15 performs the calculation of the difference information a plurality of times at a predetermined interval T starting from the time shifted by Δt. That is, the difference information calculation unit 15 performs such calculation of difference information at a predetermined interval T at two different time points (for different sets of complex transfer functions). Here, the difference information is calculated because the complex transfer function component passing through the fixed object other than the living body 50 is removed, and only the complex transfer function component passing through only the living body 50 remains.

と表せ、

である。また、l、mは測定番号を表す正の整数であり、サンプル時間である。 In the present embodiment, since there are a plurality (M _R ) of receiving antenna elements, the number of difference values (difference information) of the complex transfer function corresponding to the receiving antenna unit 11B is also plural. These are collectively defined as a complex difference channel vector. If the number of receiving antenna elements is M _R , the complex difference channel vector is

Express

It is. Further, l and m are positive integers representing measurement numbers, which are sample times.

は転置を表す。なお、図４に示す例では、Nはチャネル観測回数であり、Ｃ_tやＣ_t+Tなど
時間間隔Tにおける２つの時点を含む台形の頂点（演算に用いたデータ）の数に対応する
。観測時間T_measが３秒で、１００回測定（観測）する場合に、N＝３００となる。

Represents transposition. In the example illustrated in FIG. 4, N is the number of channel observations, and corresponds to the number of trapezoidal vertices (data used in the calculation) including two time points in the time interval T such as C _t and C _{t + T.} When the observation time T _meas is 3 seconds and measurement (observation) is performed 100 times, N = 300.

  The complex transfer function vector calculated by the complex transfer function calculation unit 14 includes a reflected wave that does not pass through the living body 50, such as a direct wave or a reflected wave derived from a fixed object, as shown in FIG. On the other hand, in the complex difference channel vector, all reflected waves that do not pass through the living body 50 are eliminated by the difference calculation of the complex transfer function vectors at two time points, and only the reflected waves derived from the living body are included. When this difference calculation is performed, there is a demerit that the complex transfer function of the reflected wave derived from the living body 50 is also subtracted. However, the amplitude and phase of the reflected wave passing through the living body 50 always fluctuate with time due to biological activities such as breathing and heartbeat. Therefore, the complex difference channel vector is not completely zero. That is, when the complex transfer function vectors at two different time points are subtracted, a complex transfer function vector passing through the living body 50 multiplied by a coefficient remains.

Note that the difference information calculation unit 15 calculates the difference information for a plurality of sets (complex transfer functions at two different time points) by taking an average of a plurality of times as described later. This is to reduce the influence of noise and improve the accuracy of direction estimation. Note that the predetermined interval T when the difference information is calculated is not a fixed value as shown in FIG. 4, but an arbitrary predetermined interval, that is, for example, 2 such as time t ′ and time t ′ + T ′ as shown in FIG. It may be a predetermined interval T ′ at one time point.

[Direction estimation processing unit 16]
The direction estimation processing unit 16 uses the difference information calculated two or more to estimate the direction in which the moving object exists using the estimation device 10 as a reference for the direction. More specifically, the direction estimation processing unit 16 calculates an instantaneous correlation matrix that is a correlation matrix of difference times that are two time points of a predetermined interval in the difference information from each of the two or more calculated difference information. Using this instantaneous correlation matrix, the arrival direction of the reflected signal is estimated by a predetermined arrival direction estimation method. Based on the estimated arrival direction of the reflected signal, the direction in which the moving object exists is estimated. Here, the predetermined direction-of-arrival estimation method is an estimation method based on a MUSIC (MUltiple SIgnal Classification) algorithm.

  In the present embodiment, the direction estimation processing unit 16 has a correlation matrix (hereinafter referred to as “instantaneous correlation matrix”) shown in (Equation 1) from the complex difference channel vector calculated by the difference information calculation unit 15 as a plurality of difference information. Is calculated. The difference time, which is two time points of the predetermined interval, is instantaneous, and thus referred to as such.

は、複素共役転置を表す。 here,

Represents a complex conjugate transpose.

  Further, the direction estimation processing unit 16 may further average (average calculation) the instantaneous correlation matrix as shown in (Expression 2). This is because, as described above, this can weaken the influence of instantaneous noise and improve the accuracy of direction estimation.

  Here, the rank of the instantaneous correlation matrix shown in (Expression 1) is 1. The instantaneous correlation matrix is a 4 × 4 vector that is a 4 × 4 matrix, and is merely a matrix in which one row component is multiplied by an integer and the number of rows is increased. Therefore, simultaneous equations cannot be solved, that is, rank 1 is obtained.

  However, it is possible to restore the rank of the correlation matrix by averaging the instantaneous correlation matrix. That is, by averaging (Equation 1) as in (Equation 2), the eigenvalue (≈rank) can be increased, so that the solvable variable (target) can be increased. Therefore, (Equation 2) has an increased eigenvalue and can improve the estimation accuracy. As will be described later, a plurality of incoming waves can be estimated simultaneously. Note that improving the accuracy by using the average calculation is a means often used in the MUSIC method described later, but is performed with a normal frequency component. On the other hand, this embodiment is different in that it is averaged in the time direction.

  In this way, the complex transfer function is recorded in a time series in a time series, and by using the recorded complex transfer functions (all), the estimation accuracy can be improved even when the observation period is relatively short (for example, several seconds). The effect that it can improve is acquired.

  The direction estimation processing unit 16 can estimate the arrival direction of the reflected signal using the instantaneous correlation matrix calculated as described above.

  Hereinafter, a method for estimating the direction using the instantaneous correlation matrix obtained from the complex difference channel vector will be described. Here, an estimation method based on the MUSIC algorithm will be described.

、

、

と書ける。 When the instantaneous correlation matrix shown in (Expression 2) is decomposed into eigenvalues,

,

,

Can be written.

は、要素数がM_Rである固有ベクトル、

は固有ベクトルに対応する固有値であり、

の順であるものとする。Lは到来波の数つまり検出対象の生体数である。 here,

Is an eigenvector with M _R elements,

Is the eigenvalue corresponding to the eigenvector,

It is assumed that the order is L is the number of incoming waves, that is, the number of living bodies to be detected.

と定義され、これにＭＵＳＩＣ法を適用する。ここで、kは波数である。 The steering vector (direction vector) of the receiving array antenna is

The MUSIC method is applied to this. Here, k is the wave number.

That is, the direction estimation processing unit 16 estimates the direction of the incoming wave by searching for the maximum value of the evaluation function P _music (θ) shown below using the steering vector of the receiving array antenna based on the MUSIC method. be able to.

  Since the direction estimation processing unit 16 can estimate the arrival direction of the reflected signal by eigenvalue decomposition of the instantaneous correlation matrix and applying the MUSIC method in this way, the direction in which the living body 50 exists is estimated from the estimated arrival direction of the reflected signal. can do. This is because the estimated arrival direction of the reflected signal and the direction in which the living body 50 exists based on the estimation device 10 substantially coincide.

[Operation of Estimation Device 10]
The operation of the estimation process of the estimation apparatus 10 configured as described above will be described. FIG. 6 is a flowchart showing an estimation process of the estimation apparatus 10 according to the first embodiment.

  First, the estimation device 10 observes a reception signal including a reflection signal transmitted from one transmission antenna element and reflected by the living body 50 for a first period corresponding to a period derived from the activity of the living body 50 (S10). ).

Then, the estimation unit 10, a plurality of received signals observed in the first period, a plurality of complex transfer function representing the propagation characteristics between each of the one transmit antenna elements and M _R receive antennas elements Calculate (S20). Since details are as described above, description thereof is omitted here. The same applies to the following.

  Next, the estimating apparatus 10 calculates two or more pieces of difference information indicating a difference between two complex transfer functions at two points in time of a predetermined interval among the plurality of complex transfer functions (S30).

  And the estimation apparatus 10 estimates the direction where the biological body 50 exists using 2 or more difference information (S40).

[Effects]
According to the estimation apparatus 10 and the estimation method of the present embodiment, by calculating the above-described difference information, only a component derived from a living body is wirelessly transmitted without using Fourier transform and at a faster processing time than when using Fourier transform. Signal processing that remains in the signal can be performed. Moreover, the estimation accuracy can be improved by using a plurality of difference information. Therefore, the direction in which the moving object exists can be estimated with high accuracy by a short observation time corresponding to the period derived from the activity of the moving object. Thereby, it is possible to estimate the direction in which the moving object is present using a radio signal in a short time and with high accuracy.

(Embodiment 2)
In the first embodiment, an estimation apparatus 10 that estimates a direction in which a moving body (living body) that is a detection target exists using difference information of complex transfer functions observed at two different times in a predetermined period, and an estimation method thereof explained. In the second embodiment, an estimation device 20 that estimates the position of a moving object (living body) that is a detection target after using the same difference information will be described.

[Configuration of Estimation Device 20]
FIG. 7 is a block diagram illustrating an example of the configuration of the estimation device 20 according to the second embodiment. FIG. 8 is a diagram illustrating an example of a detection target of the estimation apparatus 20 illustrated in FIG. Elements similar to those in FIGS. 1 and 2 are denoted by the same reference numerals, and detailed description thereof is omitted.

  7 includes a transmission antenna unit 21A, a reception antenna unit 21B, a transmission unit 22, a reception unit 23, a complex transfer function calculation unit 24, a difference information calculation unit 25, and a position estimation processing unit. 26, and the position of the moving object is estimated. The estimation device 20 shown in FIG. 7 differs from the estimation device 10 shown in FIG. 1 at least in the number of transmission antenna elements, and thereby can estimate the position of the moving object.

[Transmitter 22]
The transmission unit 22 generates a high-frequency signal used for estimating the direction of the living body 50. For example, as illustrated in FIG. 8, the transmission unit 22 transmits the generated signal (transmission wave) from M _T transmission antenna elements (transmission array antennas) included in the transmission antenna unit 21A.

[Transmitting antenna portion 21A]
The transmission antenna unit 21A includes M (M is a natural number of 2 or more) transmission antenna elements. In this embodiment, the transmitting antenna unit 21A is provided with M _T transmit antennas elements. As described above, M _T transmit antennas elements, the transmission section 22 transmits the generated signal (transmission wave).

[Receiving antenna unit 21B]
The reception antenna unit 21B includes N reception antenna elements (reception array antennas) (N is a natural number of 2 or more). In this embodiment, as in the first embodiment, the receiving antenna unit 21B is provided with M _R receive antennas elements (reception array antenna). For example, as shown in FIG. 8, M each of the _R receive antenna elements, signals transmitted from the M _T transmit antennas elements (transmit array antenna) is the signal (received reflected by the living body 50 Signal).

[Receiver 23]
The receiving unit 23 receives a reception signal that is received by each of the N reception antenna elements and includes a reflection signal transmitted from each of the M transmission antenna elements and reflected by the moving body. Observe the first period corresponding to the period derived from the activity. Here, the moving body is a living body 50 as shown in FIG. This corresponds to the period derived from the activity of the moving body. The period derived from the activity of the moving body is a period derived from the living body (biological variation period) including at least one of respiration, heartbeat, and body movement of the living body 50.

In this embodiment, the receiving section 23 is composed of M _R-number of receivers. Each of the M _R receivers converts a high-frequency signal received by a corresponding receiving antenna element into a low-frequency signal that can be processed. Receiving unit 23, at least a first period, a low frequency signal, each converted the M _R-number of receivers, and transmits the complex transfer function calculation unit 24.

[Complex transfer function calculation unit 24]
The complex transfer function calculation unit 24 calculates a plurality of complex transfer functions representing the propagation characteristics between the M transmission antenna elements and the N reception antenna elements from the plurality of reception signals observed in the first period. To do.

In the present embodiment, the complex transfer function calculation unit 24 expresses a propagation characteristic between M _T transmission antenna elements and M _R reception antenna elements from a low-frequency signal transmitted from the reception unit 23. Calculate the complex transfer function. Hereinafter, a more specific description will be given with reference to FIG.

In FIG. 8, both the transmission array antenna and the reception array antenna are linear arrays with an element interval d, and the directions of the living body 50 viewed from the front of each of the transmission array antenna and the reception array antenna are θ _T and θ _R. It is assumed that the distance between the living body and the transmission / reception array antenna is sufficiently larger than the opening width of the array antenna, and signals passing through the living body that arrive at the departure and reception array antennas from the transmission array antenna can be regarded as plane waves.

As shown in FIG. 8, a transmission wave transmitted at an angle θ _T from M _T transmission antenna elements (transmission array antennas) of the transmission antenna unit 21A is reflected by the living body 50, and is transmitted to the reception array antenna at an angle θ _R. To reach.

  In this case, the complex transfer function calculation unit 24 can calculate the complex transfer function vector from the complex received signal vector observed using the receiving array antenna. The complex transfer function vector is in matrix form, but can be calculated in the same manner as in the first embodiment. The calculated complex transfer function matrix includes a reflected wave that does not pass through the living body 50, such as a direct wave or a reflected wave derived from a fixed object, as described above.

[Difference information calculation unit 25]
The difference information calculation unit 25 sequentially records the calculated plurality of complex transfer functions in a time series that is the order in which the plurality of received signals are observed. Then, the difference information calculation unit 25 is difference information indicating a difference between two complex transfer functions at two points in time at a predetermined interval among the plurality of complex transfer functions, and is represented by an M × N-dimensional matrix. 2 or more is calculated. Here, the start point of two time points of a predetermined interval in each of the two or more pieces of difference information is a different time. Further, the predetermined interval may be approximately half of the cycle derived from the living body 50 (biological variation cycle).

  Note that the two time points of the predetermined interval used when calculating the difference information are the same as those described in the first embodiment with reference to FIG.

  Also in the present embodiment, the difference information calculation unit 25 calculates difference information indicating a difference between two complex transfer functions at two different points in time of the predetermined interval T among the complex transfer functions calculated by the complex transfer function calculation unit 24. To do. Further, the difference information calculation unit 25 performs the calculation of the difference information for two further different time points (different sets of complex transfer functions). Here, the difference information is calculated because the complex transfer function component passing through the fixed object other than the living body 50 is removed and only the complex transfer function component passing through only the living body 50 remains as in the first embodiment. It is.

In the present embodiment, there are a plurality of transmission antenna elements and reception antenna elements. Therefore, the number of difference values (difference information) of the complex transfer function corresponding to the transmission antenna unit 21A and the reception antenna unit 21B is transmission antenna element × number of reception antenna elements (M _R × M _T ). It is defined as a channel matrix H (l, m). The difference information calculation unit 25 calculates a complex difference channel matrix H (l, m) that can be expressed as follows as difference information. In this complex difference channel matrix H (l, m), all reflected waves that do not pass through the living body 50 are eliminated by the difference calculation, and therefore only the reflected waves derived from the living body 50 are included.

である。また、l、mは、測定番号を表す正の整数であり、サンプル時間である。 here,

It is. Further, l and m are positive integers representing measurement numbers, which are sample times.

[Position estimation processing unit 26]
The position estimation processing unit 26 estimates the position where the moving object exists using the difference information calculated two or more. More specifically, first, the position estimation processing unit 26 calculates an instantaneous correlation matrix that is a correlation matrix of difference times that are two time points of a predetermined interval in the difference information, from each of two or more calculated difference information. . Next, the position estimation processing unit 26 uses the calculated instantaneous correlation matrix to transmit the transmission direction of the transmission signal transmitted from the transmission antenna unit 21A to the moving object and the arrival direction of the reflected signal by a predetermined arrival direction estimation method. Is estimated. And the position estimation process part 26 estimates the position where a moving body exists based on the transmission direction of the estimated transmission signal, and the arrival direction of the estimated reflected signal. Here, the predetermined direction-of-arrival estimation method is an estimation method based on the MUSIC algorithm.

  In the present embodiment, the position estimation processing unit 26 calculates an instantaneous correlation matrix from the complex difference channel matrix calculated by the difference information calculation unit 25 as a plurality of difference information.

More specifically, the position estimation processing unit 26 rearranges the elements of the complex difference channel matrix H (l, m) calculated by the difference information calculation unit 25, and displays M _R M _T × shown in (Expression 3). A complex difference channel with a vector of 1 is calculated.

  Here, vec (·) means conversion of a matrix into a vector.

  Next, the position estimation processing unit 26 calculates an instantaneous correlation matrix shown in (Expression 4) from the complex difference channel vector.

  Further, the position estimation processing unit 26 may further average (average calculation) this instantaneous correlation matrix as shown in (Expression 5). This is because, as described above, this can weaken the influence of instantaneous noise and improve the accuracy of direction estimation.

  Here, the rank of the instantaneous correlation matrix of (Equation 4) is 1, but as described in the first embodiment, the rank of the correlation matrix can be recovered by the average calculation of the instantaneous correlation matrix. This not only improves the estimation accuracy, but also enables simultaneous estimation of a plurality of incoming waves.

  In this way, the complex transfer function is recorded in a time series in a time series, and by using the recorded complex transfer functions (all), the estimation accuracy can be improved even when the observation period is relatively short (for example, several seconds). The effect that it can improve is acquired.

  The position estimation processing unit 26 can estimate the position of the living body 50 using the instantaneous correlation matrix calculated as described above.

  Next, a method for performing direction estimation using the instantaneous correlation matrix obtained from the complex difference channel matrix will be described. In this embodiment, an estimation method based on the MUSIC algorithm will be described.

、

、

と書ける。 When the instantaneous correlation matrix shown in (Equation 5) is decomposed into eigenvalues,

,

,

Can be written.

は、要素数がM_Rである固有ベクトル、

は固有ベクトルに対応する固有値であり、

の順であるものとする。Ｌは到来波の数つまり検出対象の生体数である。 here,

Is an eigenvector with M _R elements,

Is the eigenvalue corresponding to the eigenvector,

It is assumed that the order is L is the number of incoming waves, that is, the number of living bodies to be detected.

、受信アレーアンテナのステアリングベクトル（方向ベクトル）は、

と定義される。ここで、ｋは波数である。さらに、これらのステアリングベクトルを乗算し、

と、送受信アレーアンテナ双方の角度情報を考慮したステアリングベクトルを定義し、これにＭＵＳＩＣ法を適用する。 The steering vector (direction vector) of the transmitting array antenna is

The steering vector (direction vector) of the receiving array antenna is

It is defined as Here, k is a wave number. Then multiply these steering vectors,

Then, a steering vector is defined in consideration of angle information of both the transmitting and receiving array antennas, and the MUSIC method is applied thereto.

That is, the position estimation processing unit 26 can estimate the direction of the incoming wave by searching for the maximum value with the evaluation function P _music (θ) shown below using the multiplied steering vector based on the MUSIC method. .

In this embodiment, since it is necessary to search for the maximum value of the evaluation function for two angles (θ _T, θ _R ), a two-dimensional search process is performed. Then, the position estimation processing unit 26 estimates the transmission direction of the transmission wave to the living body 50 and the arrival direction of the reflected wave from the living body 50 from the two angles (θ _T, θ _R ) thus obtained, The position of the living body 50 is estimated from the estimated intersection of the two directions.

[Operation of Estimation Device 20]
The operation of the estimation process of the estimation apparatus 20 configured as described above will be described. FIG. 9 is a flowchart illustrating an estimation process of the estimation device 20 according to the second embodiment.

First, the estimation device 20 is transmitted from the M _T transmit antennas elements, a reception signal including a reflected signal reflected by the body 50, is observed for the first period corresponding to a period from the activity of the living body 50 ( S10A).

Next, the estimating apparatus 20 calculates a complex transfer function representing the propagation characteristics between the M _T transmitting antenna elements and the M _R receiving antenna elements from the plurality of received signals observed in the first period. A plurality are calculated (S20A). Since details are as described above, description thereof is omitted here. The same applies to the following.

  Next, the estimating apparatus 20 calculates two or more pieces of difference information indicating a difference between two complex transfer functions at two points in time of a predetermined interval among the plurality of complex transfer functions (S30A).

  And the estimation apparatus 20 estimates the position where the biological body 50 exists using 2 or more difference information (S40A).

[Effects]
According to the estimation device 20 and the estimation method of the present embodiment, by calculating the difference information described above, only the component derived from the living body is wirelessly transmitted without using the Fourier transform and with a processing time faster than when using the Fourier transform. Signal processing that remains in the signal can be performed. Moreover, the estimation accuracy can be improved by using a plurality of difference information. Therefore, the direction in which the moving object exists can be estimated with high accuracy by a short observation time corresponding to the period derived from the activity of the moving object. Accordingly, it is possible to estimate the position where the moving object is present using a radio signal in a short time and with high accuracy.

  Here, since it evaluated by experiment in order to confirm the effect which concerns on Embodiment 2, it demonstrates below.

  FIG. 10 is a diagram illustrating a concept of an experiment using the estimation method according to the second embodiment.

Both the transmission array antenna (Tx array) and the reception array antenna (Rx array) shown in FIG. 10 have a 4 × 4 MIMO (Multiple Input Multiple Output) configuration using a four-element patch array antenna. Also, an SP4T (Single-Pole-4-Throw) switch was used on the transmission side, and four receivers were used on the reception side. In this experiment, MIMO channels were measured using these devices.

Here, the array element spacing of the transmitting and receiving antennas was set to 0.5 wavelength, the distance D between transmitting and receiving was set to 4.0 m, and the antenna height h was set to 1.0 m, which is the height of the chest when a human (Living-Body) stands upright. A 2.47125 GHz unmodulated continuous wave (CW) was transmitted from the transmitter, the sampling frequency (channel acquisition speed) was 7.0 Hz, and the channel measurement time was 3.3 seconds. At the time of channel measurement, the tester was unattended except for the subject, and the subject faced the front with respect to the wall on the antenna side.

  FIG. 11 is a diagram illustrating an experimental result using the estimation method according to the second embodiment. FIG. 11 shows the result of biological position estimation when there are two subjects. The subject's standing position during the experiment was subject 1 (X = 1.0 m, Y = 2.5 m) and subject 2 (X = 3.0 m, Y = 2.0 m). In FIG. 11, the actual position of the subject is indicated by ◯, and the position of the subject estimated by searching for the maximum value of the evaluation function is indicated by ◇. As shown in FIG. 11, even in the case of two subjects, the position of the subject estimated by searching for the maximum value of the evaluation function appears near the actual subject (living body). Therefore, it can be seen that the estimation method according to the second embodiment can estimate the positions of a plurality of persons.

  FIG. 12 is a diagram illustrating another experimental result using the estimation method according to the second embodiment. A solid line A in FIG. 12 shows a cumulative probability distribution function (CDF: Cumulative Distribution Function) of position estimation errors when the biological position estimation is attempted 1500 times when there are two subjects. The dotted line B in FIG. 12 shows the result of the biological position estimation method (Patent Document 3) using the conventional Fourier transform on the time-varying channel of 3.28 seconds, which is the experimental condition (cumulative probability of position estimation error). Distribution) is also shown as a comparative example.

From FIG. 12, the CDF90% value in the comparative example using Fourier transform is 1.12 m, and the CDF90% value in the case of using the estimation method according to the second embodiment is 0.39 m. Therefore, the second embodiment
It can be seen that the estimation method according to is able to estimate with an accuracy of 0.73m. Thus, it has been shown that the living body position can be estimated with high accuracy even in a short observation time according to the present embodiment.

  As described above, according to the present invention, by calculating difference information that is a difference between propagation channels at two different times in a predetermined period, processing time that is faster than when Fourier transform is used without using Fourier transform. Thus, it is possible to perform signal processing in which only a component derived from a living body remains in the radio signal. Moreover, the estimation accuracy can be improved by using a plurality of difference information. As a result, the direction in which the moving object exists can be estimated with high accuracy by a short observation time corresponding to the period derived from the activity of the moving object. Accordingly, it is possible to realize an estimation apparatus and an estimation method that can estimate the direction and position where a moving object exists using a radio signal in a short time and with high accuracy.

  As described above, the estimation device and the estimation method according to one aspect of the present invention have been described based on the embodiments. However, the present invention is not limited to these embodiments. Unless it deviates from the meaning of this invention, the form which made | forms this embodiment the various deformation | transformation which those skilled in the art think, or the structure constructed | assembled combining the component in different embodiment is also contained in the scope of the present invention.

  For example, in the first and second embodiments, direction estimation and position estimation of the living body 50 have been described as examples, but the present invention is not limited to the living body 50. When a high-frequency signal is irradiated, the present invention can be applied to various moving objects (machines or the like) that give a Doppler effect to a reflected wave by the activity.

  In addition, the present invention can be realized not only as an estimation device including such characteristic components, but also as an estimation method using the characteristic components included in the estimation device as steps. it can. It can also be realized as a computer program that causes a computer to execute the characteristic steps included in such a method. Needless to say, such a computer program can be distributed via a computer-readable non-transitory recording medium such as a CD-ROM or a communication network such as the Internet.

  INDUSTRIAL APPLICABILITY The present invention can be used in an estimation apparatus and an estimation method for estimating the direction and position of a moving object using radio signals, and in particular, a measuring instrument that measures the direction and position of a moving object including a living body and a machine, and the direction and position of the moving object. The present invention can be used for an estimation device and an estimation method that are mounted on home appliances that perform corresponding control, monitoring devices that detect the intrusion of moving objects, and the like.

DESCRIPTION OF SYMBOLS 10, 20 Estimation apparatus 11 Antenna part 11A, 21A Transmission antenna part 11B, 21B Reception antenna part 12 Transmitter 13, 23 Reception part 14, 24 Complex transfer function calculation part 15, 25 Difference information calculation part 16 Direction estimation process part 22 Transmission Unit 26 position estimation processing unit 50 living body

Claims (6)

On the computer,
A received signal received by each of the N receiving antenna elements, and a period derived from the activity of the moving object among the received signals transmitted from one transmitting antenna element and including a reflected signal reflected by the moving object The received signal observed for the first period corresponding to
Calculating a plurality of complex transfer functions representing propagation characteristics between the transmission antenna element and each of the N reception antenna elements from the plurality of reception signals observed in the first period;
(i) sequentially recording the plurality of calculated complex transfer functions in a time series in the order in which the plurality of received signals are observed; and (ii) among the plurality of complex transfer functions at two points in time at a predetermined interval. Calculating two or more pieces of difference information representing a difference between two complex transfer functions and represented by an N-dimensional vector;
Using the difference information calculated two or more, to execute a process of estimating the direction in which the moving object exists, using a device having at least the N receiving antenna elements as a reference of the direction;
program. The starting point of the two time points of the predetermined interval in each of the two or more difference information is a different time.
The program according to claim 1. The moving body is a living body,
The program according to claim 1 or 2. The period is a period derived from a living body including at least one of respiration, heartbeat, and body movement of the living body, and the predetermined interval is substantially half of the period derived from the living body.
The program according to claim 3. In the process of estimating the direction in which the moving object exists,
From each of the two or more calculated difference information, an instantaneous correlation matrix that is a correlation matrix of a difference time that is two time points of a predetermined interval in the difference information is calculated,
Using the calculated instantaneous correlation matrix, the arrival direction of the reflected signal is estimated by a predetermined arrival direction estimation method,
Based on the estimated arrival direction of the reflected signal, the direction in which the moving object exists is estimated.
The program according to any one of claims 1 to 4. The predetermined direction-of-arrival estimation method is an estimation method based on a MUSIC (MUltiple SIgnal Classification) algorithm.
The program according to claim 5.

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