Estimation device, estimation method, and program

Abstract

An estimation device (101) performs a prescribed process for each of N×M×S elements in a first complex transfer function matrix that includes, as elements of a three-dimensional array of N×M×S, complex transfer functions respectively obtained for S subcarriers and N×M combinations, and thereby calculates a second complex transfer function matrix. In the prescribed process, an amplitude average of a plurality of first elements including an element to be processed is calculated, and the element to be processed is divided by the amplitude average. The plurality of first elements are included in S×M elements obtained for one reception antenna element which corresponds to the element to be processed.

Description

Estimation device, estimation method, and program

[0001] The present disclosure relates to an estimation device and an estimation method for estimating a distance or a position to a living body using a wireless signal.

[0002] Methods using wireless signals have been considered as a method for determining the position of a person (see, for example, Patent Documents 1 to 4). Patent Documents 1, 2, and 3 disclose techniques for estimating the position and state of a person to be detected by analyzing components including Doppler shift using differential calculation. Patent Documents 4 and 5 disclose Doppler sensors using Orthogonal Frequency Division Multiplexing (OFDM) signals.

[0003] JP 2015-117972 A JP 2017-129558 A JP 2018-008021 A JP 2012-088279 A JP 2012-137340 A

[0004] H. Yamada, M. Ohmiya, Y. Ogawa and K. Itoh, “Superresolution techniques for time-domain measurements with a network analyzer,” in IEEE Transactions on Antennas and Propagation, vol. 39, no. 2, pp. 177-183, Feb. 1991

[0005] With conventional methods, it is difficult to estimate the distance from the estimation device to the living body, the direction to the living body, and the like with high accuracy.

[0006] In order to achieve the above object, an estimation device according to an embodiment of the present disclosure includes a transmission signal generation unit that generates a multicarrier signal in which S (S is a natural number of 2 or more) subcarrier signals are modulated, a transmission antenna unit having M (M is a natural number of 1 or more) transmission antenna elements, a transmission unit that processes the multicarrier signal and outputs it to the transmission antenna unit, thereby transmitting the multicarrier signal to the transmission antenna unit, and a reception antenna unit having N (N is a natural number of 1 or more) reception antenna elements, and observes, for a first period corresponding to a cycle derived from activity of the living body, reception signals received by each of the N reception antenna elements, the reception signals including reflected signals formed by the multicarrier signals transmitted from each of the M transmission antenna elements being reflected or scattered by a living body, and a receiving unit that calculates, for each of N×M combinations that are combinations of a transmitting antenna element with a receiving antenna element, a plurality of complex transfer functions that represent propagation characteristics between the transmitting antenna element and the receiving antenna element in that combination, for each of S subcarriers to which the S subcarrier signals respectively correspond; and a matrix calculation unit that calculates a second complex transfer function matrix by performing a predetermined process on each of N×M×S elements in a first complex transfer function matrix that includes the complex transfer functions obtained for each of the S subcarriers and for each of the N×M combinations as each element of an N×M×S three-dimensional array, wherein the predetermined process is a process of calculating an amplitude average of a plurality of first elements including an element to be processed, and dividing the element to be processed by the amplitude average, and the plurality of first elements are included in the S×M elements obtained for one receiving antenna element corresponding to the element to be processed.

[0007] An estimation method according to an embodiment of the present disclosure is an estimation method by an estimation device including a transmitting antenna unit having M (M is a natural number equal to or greater than 1) transmitting antenna elements and a receiving antenna unit having N (N is a natural number equal to or greater than 1) receiving antenna elements, the estimation method comprising: generating a multicarrier signal in which S (S is a natural number equal to or greater than 2) subcarrier signals are modulated; processing the multicarrier signal and outputting it to the transmitting antenna unit, thereby transmitting the multicarrier signal to the transmitting antenna unit; observing received signals received by each of the N receiving antenna elements, the received signals including reflected signals formed by the multicarrier signals transmitted from each of the M transmitting antenna elements being reflected or scattered by a living body, for a first period corresponding to a cycle derived from activity of the living body; and using the plurality of received signals observed in the first period, calculating a frequency of each of the M transmitting antenna elements. and each of the N receiving antenna elements, a plurality of complex transfer functions representing propagation characteristics between the transmitting antenna element and the receiving antenna element in that combination are calculated for each of the S subcarriers to which the S subcarrier signals respectively correspond, and a second complex transfer function matrix is ​​calculated by performing a predetermined process on each of the N×M×S elements in a first complex transfer function matrix including the complex transfer functions obtained for each of the S subcarriers and for each of the N×M combinations as each element of an N×M×S three-dimensional array, the predetermined process being a process of calculating an amplitude average of a plurality of first elements including an element to be processed, and dividing the element to be processed by the amplitude average, and the plurality of first elements are included in the S×M elements obtained for one receiving antenna element corresponding to the element to be processed.

[0008] These general or specific aspects may be realized by a system, an integrated circuit, a computer program, or a computer-readable recording medium such as a CD-ROM, or may be realized by any combination of an apparatus, a system, a method, an integrated circuit, a computer program, and a recording medium.

[0009] According to the present disclosure, the position of a living body can be estimated with higher accuracy.

[0010] FIG. 1 is a block diagram showing an example of the configuration of an estimation device according to a first embodiment. FIG. 2 is a diagram illustrating the relationship between a transmission signal, a channel, and a reception signal. FIG. 3 is a diagram illustrating propagation characteristics at each timing in MIMO. FIG. 4 is a schematic diagram showing a first error. FIG. 5 is a diagram illustrating an example of the first error. FIG. 6 is a schematic diagram illustrating a second error. FIG. 7 is a diagram illustrating an example of the second error. FIG. 8 is a schematic diagram illustrating a third error. FIG. 9 is a schematic diagram illustrating the relationship between the third error and the channel. FIG. 10 is a schematic diagram illustrating the relationship between frequency and the slope of the phase difference. FIG. 11 is a schematic diagram illustrating the phase of a time-domain biological component transfer function matrix. FIG. 12 is a schematic diagram illustrating the positional relationship between a living body, a transmitting antenna unit, and a receiving antenna unit in MIMO, and the position of the living body. FIG. 13 is a schematic diagram illustrating the positional relationship between a living body, multiple transmitting antenna units, and a receiving antenna unit in MISO, and the position of the living body. FIG. 14 is a flowchart showing estimation processing of the estimation device according to the first embodiment. FIG. 15 is a block diagram showing an example of the configuration of an estimation device according to a second embodiment. Fig. 16 is a diagram for explaining propagation characteristics at each timing of SIMO. Fig. 17 is a schematic diagram showing the positional relationship between a living body, a transmitting antenna unit, and a receiving antenna unit, and the position of the living body in SIMO. Fig. 18 is a schematic diagram showing the positional relationship between a living body, a transmitting antenna unit, and a receiving antenna unit, and the position of the living body in SISO. Fig. 19 is a flowchart showing estimation processing of an estimation device in embodiment 2. Fig. 20 is a diagram showing experimental conditions using the estimation method according to embodiment 1. Fig. 21 is a diagram showing an example of estimation results using the estimation method according to embodiment 1. Fig. 22 is a diagram showing a statistical example of estimation errors using the estimation method according to embodiment 1.

[0011] (Findings that Form the Basis of the Present Disclosure) Methods that utilize wireless signals are being considered as methods for determining the location of a person, etc.

[0012] For example, Patent Documents 1 and 2 disclose a method of transmitting a radio signal to a predetermined area, receiving the radio signal reflected by a detection target using multiple antennas, and estimating a complex transfer function between the transmitting and receiving antennas. The complex transfer function is a function composed of complex numbers that represents the relationship between input and output, and represents the propagation characteristics 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. Furthermore, Patent Document 3 discloses a method of estimating the posture of a living body using a radar cross section (RCS) calculated from the received power, using a configuration similar to Patent Document 2. The RCS is an index that represents the area of ​​an object that reflects a transmitted wave, and the RCS of a living body varies depending on the posture of the living body.

[0013] Patent Document 1 further discloses a processing device capable of determining the position or status of a person to be detected by analyzing components including Doppler shift using a Fourier transform. More specifically, the processing device records the time changes of elements of a complex transfer function and performs a Fourier transform on the time waveform. Living organisms, such as people, impart a slight Doppler effect to the reflected waves due to biological activities such as breathing and heartbeat. Therefore, the components including Doppler shift obtained from the reflected waves include the influence of the living organism. On the other hand, the components without Doppler shift obtained from the reflected waves are not influenced by the living organism. In other words, the components without Doppler shift correspond to reflected waves from fixed objects or direct waves between transmitting and receiving antennas. In other words, the position or status of the person to be detected can be obtained by using components included in a predetermined frequency range in the Fourier-transformed waveform.

[0014] Patent Document 2 discloses a method for extracting components containing slight Doppler shifts due to the influence of living organisms by recording the time changes of elements of a complex transfer function and analyzing the difference information. In other words, this method makes it possible to know the position and state of a person to be detected using the difference information.

[0015] On the other hand, Patent Document 3 discloses an OFDM Doppler radar that transmits pulses using OFDM signals and detects the Doppler shift caused by a target moving object. Also, Patent Document 4 discloses a high-speed processing method for OFDM Doppler radar that does not require Fourier transform.

[0016] Furthermore, Patent Documents 4 and 5 disclose techniques for improving the estimation accuracy of the complex transfer function between transmitting and receiving antennas by transmitting OFDM signals. Patent Document 5 discloses that the received noise component can be reduced by averaging the complex transfer function for each subcarrier.

[0017] However, the methods of Patent Documents 1, 2, and 3 transmit unmodulated waves, making it difficult to use commercially available devices and requiring dedicated hardware. In other words, currently popular communication devices cannot be used, and users must install dedicated hardware in addition to their existing communication devices.

[0018] Furthermore, in the methods of Patent Documents 4 and 5, in order to obtain sufficient accuracy, the transmission pulse needs to be steep, which requires a wide frequency band, and therefore the hardware costs are higher than those of communication devices for consumer use.

[0019] The technology of Non-Patent Document 1 uses a measuring device such as a network analyzer to transmit and receive signals of multiple frequencies, thereby making it possible to estimate the ToF (Time of Flight) between a transmitting antenna and a receiving antenna, or a distance that can be calculated from the ToF. This utilizes the property that, similar to a range sensor using an FMCW (Frequency Modulated Continuous Wave) radar, when two signals of different frequencies are transmitted with the same phase, the phase received by the receiving antenna changes depending on the frequency difference of the signals and the distance they propagate between the antennas. The technology of Non-Patent Document 1 further improves resolution by performing ToF estimation using the MUSIC (Multiple Signal Classification) method.

[0020] However, this technology requires that the transmitter and receiver operate on the same reference frequency or be highly synchronized, making it difficult to apply to home devices such as wireless LANs. Also, it can only estimate the distance between antennas, making it difficult to estimate the distance between a device and, for example, a living body that does not have a special device.

[0021] Therefore, the present inventors have come up with an estimation device etc. that can estimate the position etc. of a living body with higher accuracy.

[0022] That is, the estimation device according to the first aspect of the present disclosure includes a transmission signal generation unit that generates a multicarrier signal in which S (S is a natural number of 2 or more) subcarrier signals are modulated, a transmission antenna unit having M (M is a natural number of 1 or more) transmission antenna elements, a transmission unit that processes the multicarrier signal and outputs it to the transmission antenna unit, thereby causing the multicarrier signal to be transmitted by the transmission antenna unit, and a reception antenna unit having N (N is a natural number of 1 or more) reception antenna elements, and observes, for a first period corresponding to a cycle derived from activity of the living body, reception signals received by each of the N reception antenna elements, the reception signals including reflected signals formed by the multicarrier signals transmitted from each of the M transmission antenna elements being reflected or scattered by a living body, and and a matrix calculation unit that calculates a second complex transfer function matrix by performing a predetermined process on each of N×M×S elements in a first complex transfer function matrix that includes the complex transfer functions obtained for each of the S subcarriers and for each of the N×M combinations as elements of an N×M×S three-dimensional array, wherein the predetermined process calculates an amplitude average of a plurality of first elements including a processing target element and divides the processing target element by the amplitude average, and the plurality of first elements are included in the S×M elements obtained for one receiving antenna element corresponding to the processing target element.

[0023] According to this, a predetermined process of calculating an amplitude average of a plurality of first elements that are included in the S×M elements obtained for one receiving antenna element corresponding to the element to be processed and that include the element to be processed, and dividing the element to be processed by the amplitude average is performed for each of the N×M×S elements in the first complex transfer function matrix, so that it is possible to reduce the first error that is imparted to the received signal by each receiving antenna element, and therefore it is possible to estimate the position of a living body with high accuracy.

[0024] Furthermore, with this configuration, by using a multi-carrier signal such as OFDM for the transmission signal, it is possible to realize a bio-radar that measures the distance and position of a living body by utilizing existing communication devices. For example, receivers of multi-carrier signals such as OFDM are already widespread in mobile phones, television broadcast receivers, wireless LAN devices, etc., and it is possible to realize a bio-radar that measures the distance and position of a living body at lower cost than when using an unmodulated signal.

[0025] An estimation device according to a second aspect of the present disclosure is an estimation device according to the first aspect, wherein the plurality of first elements are M elements obtained for one receiving antenna element corresponding to the element to be processed and one subcarrier corresponding to the element to be processed.

[0026] Therefore, the first error can be reduced by using the amplitude average of M elements obtained for one receiving antenna element corresponding to the element to be processed and one subcarrier corresponding to the element to be processed.

[0027] An estimation device according to a third aspect of the present disclosure is the estimation device according to the first aspect, wherein the plurality of first elements are S elements obtained for one receiving antenna element corresponding to the element to be processed and one transmitting antenna element corresponding to the element to be processed.

[0028] Therefore, the first error can be reduced by using the amplitude average of S elements obtained for one receiving antenna element corresponding to the element to be processed and one transmitting antenna element corresponding to the element to be processed.

[0029] An estimation device according to a fourth aspect of the present disclosure is the estimation device according to the first aspect, wherein the plurality of first elements are the S×M elements.

[0030] Therefore, the first error can be reduced by using the amplitude average of the S×M elements.

[0031] An estimation device according to a fifth aspect of the present disclosure is an estimation device according to any one of the first to third aspects, wherein the matrix calculation unit further calculates an offset value with respect to a reference phase calculated from the positional relationship between the transmitting antenna unit and the receiving antenna unit, and calculates a third complex transfer function matrix by correcting the second complex transfer function matrix based on the offset value.

[0032] This makes it possible to reduce the third error with respect to the reference phase, thereby enabling the position of the living body to be estimated with higher accuracy.

[0033] An estimation device according to a sixth aspect of the present disclosure is the estimation device according to the fifth aspect, wherein the matrix calculation unit converts the second complex transfer function matrix into a frequency response matrix or a frequency response vector, extracts a frequency response matrix or a frequency response vector corresponding to a direct wave between the transmitting antenna unit and the receiving antenna unit, calculates an ideal complex transfer function corresponding to the direct wave, calculates correction values ​​as the offset values ​​for correcting phase errors in S second elements of the second complex transfer function matrix for each of the N×M combinations based on the ideal complex transfer function and the frequency response matrix or the frequency response vector, and calculates the third complex transfer function matrix in which the phase errors have been corrected based on the correction values.

[0034] Therefore, phase errors in the subcarrier direction can be eliminated, and the distance from the estimation device to the living body can be measured with higher accuracy.

[0035] An estimation device according to a seventh aspect of the present disclosure is the estimation device according to the fifth aspect, wherein the matrix calculation unit calculates an average value by averaging all elements or a plurality of third elements of the second complex transfer function matrix in the real part direction and the imaginary part direction, respectively, to calculate an ideal complex transfer function corresponding to a direct wave between the transmitting antenna unit and the receiving antenna unit, calculates correction values ​​as the offset values ​​for correcting phase errors in S second elements of the second complex transfer function matrix for each of the N×M combinations based on the ideal complex transfer function and the average value, and calculates the third complex transfer function matrix in which the phase errors have been corrected based on the correction values.

[0036] Therefore, phase errors in the subcarrier direction can be eliminated, and the distance from the estimation device to the living body can be measured with higher accuracy.

[0037] An estimation device according to an eighth aspect of the present disclosure is the estimation device according to any one of the fifth to seventh aspects, wherein the matrix calculation unit further calculates a fourth complex transfer function matrix by applying a time-direction MMSE (Minimum Mean Square Error) filter, in which a direct wave between the transmitting antenna unit and the receiving antenna unit is set as a reference signal, to the second complex transfer function matrix or the third complex transfer function matrix.

[0038] Therefore, phase errors in the subcarrier direction can be eliminated, and the distance from the estimation device to the living body can be measured with higher accuracy.

[0039] An estimation device according to a ninth aspect of the present disclosure is the estimation device according to the first aspect, wherein the first complex transfer function matrix has N×M×S corrected elements obtained by dividing all elements of the N×M×S complex transfer functions by direct wave components that do not pass through the living body, and which are direct wave components extracted using one or more elements of N×M×S complex transfer functions, which are a set of the complex transfer functions obtained for each of the S subcarriers and each of the N×M combinations.

[0040] This makes it possible to reduce the first error, which is a component corresponding to at least one of (1) clock fluctuations between a transmitter consisting of a transmission signal generation unit and a transmission unit that transmits from a transmission antenna unit, and a receiver consisting of a reception unit that receives by a reception antenna unit, and (2) timing fluctuations in digital-to-analog conversion of a transmission signal or analog-to-digital conversion of a reception signal.As a result, it is possible to estimate the position of a living body with higher accuracy.

[0041] An estimation device according to a tenth aspect of the present disclosure is an estimation device according to any one of the fifth to eighth aspects, wherein M and N are 2 or greater, and the estimation device further includes an estimation unit that uses the third complex transfer function matrix calculated by the matrix calculation unit to estimate a position of the living body from a first angle that is the direction of the living body as seen from the M transmitting antenna elements and a second angle that is the direction of the living body as seen from the N receiving antenna elements.

[0042] Therefore, the position of the living body relative to the estimation device can be estimated with higher accuracy.

[0043] An estimation device according to an eleventh aspect of the present disclosure is an estimation device according to any one of the fifth to eighth aspects, wherein at least one of M and N is 2 or greater, and the estimation device further includes an estimation unit that uses the third complex transfer function matrix calculated by the matrix calculation unit to estimate a third distance, which is the sum of a first distance between the transmitting antenna unit and the living body and a second distance between the receiving antenna unit and the living body, and estimates a first angle or a second angle, which is the direction of the living body as seen from two or more antenna elements of the transmitting antenna unit or the receiving antenna unit, and estimates the position of the living body from the third distance and the first angle or the second angle.

[0044] Therefore, the position of the living body relative to the estimation device can be estimated with higher accuracy.

[0045] An estimation device according to a twelfth aspect of the present disclosure is an estimation device according to any one of the fifth to eighth aspects, wherein M and N are 1, and the estimation device includes an estimation unit that estimates a third distance, which is the sum of a first distance between the transmitting antenna unit and the living body and a second distance between the receiving antenna unit and the living body, using the third complex transfer function matrix calculated by a pre-matrix calculation unit.

[0046] Therefore, the distance to the living body based on the estimation device can be estimated with higher accuracy.

[0047] An estimation device according to a thirteenth aspect of the present disclosure is the estimation device according to the eleventh aspect, wherein the estimation unit estimates the first distance, the second distance, the first angle, and the second angle using any one of a MUSIC (Multiple Signal Classification) method, a beamformer method, and a Capon method.

[0048] Therefore, the distance to the living body based on the estimation device can be estimated with higher accuracy.

[0049] An estimation method according to a fourteenth aspect of the present disclosure is an estimation method by an estimation device including a transmitting antenna unit having M (M is a natural number equal to or greater than 1) transmitting antenna elements and a receiving antenna unit having N (N is a natural number equal to or greater than 1) receiving antenna elements, the estimation method comprising: generating a multicarrier signal in which S (S is a natural number equal to or greater than 2) subcarrier signals are modulated; processing the multicarrier signal and outputting it to the transmitting antenna unit, thereby transmitting the multicarrier signal to the transmitting antenna unit; observing received signals received by each of the N receiving antenna elements, the received signals including reflected signals formed by the multicarrier signals transmitted from each of the M transmitting antenna elements being reflected or scattered by a living body, for a first period corresponding to a cycle derived from activity of the living body; and using the plurality of received signals observed in the first period, calculating a frequency of each of the M transmitting antenna elements. and each of the N receiving antenna elements, a plurality of complex transfer functions representing propagation characteristics between the transmitting antenna element and the receiving antenna element in that combination are calculated for each of the S subcarriers to which the S subcarrier signals respectively correspond, and a second complex transfer function matrix is ​​calculated by performing a predetermined process on each of the N×M×S elements in a first complex transfer function matrix including the complex transfer functions obtained for each of the S subcarriers and for each of the N×M combinations as each element of an N×M×S three-dimensional array, the predetermined process being a process of calculating an amplitude average of a plurality of first elements including an element to be processed, and dividing the element to be processed by the amplitude average, and the plurality of first elements are included in the S×M elements obtained for one receiving antenna element corresponding to the element to be processed.

[0050] According to this, a predetermined process of calculating an amplitude average of a plurality of first elements that are included in the S×M elements obtained for one receiving antenna element corresponding to the element to be processed and that include the element to be processed, and dividing the element to be processed by the amplitude average is performed for each of the N×M×S elements in the first complex transfer function matrix, so that it is possible to reduce the first error that is imparted to the received signal by each receiving antenna element, and therefore it is possible to estimate the position of a living body with high accuracy.

[0051] Furthermore, with this configuration, by using a multi-carrier signal such as OFDM for the transmission signal, it is possible to realize a bio-radar that measures the distance and position of a living body by utilizing existing communication devices. For example, receivers of multi-carrier signals such as OFDM are already widespread in mobile phones, television broadcast receivers, wireless LAN devices, etc., and it is possible to realize a bio-radar that measures the distance and position of a living body at lower cost than when using an unmodulated signal.

[0052] A program according to a fifteenth aspect of the present disclosure is a program for causing a computer to execute the estimation method according to the fourteenth aspect.

[0053] With this configuration, by using a multi-carrier signal such as OFDM for the transmission signal, it is possible to realize a bio-radar that measures the distance and position of a living body by utilizing existing communication devices. For example, receivers for multi-carrier signals such as OFDM are already widespread in mobile phones, television broadcast receivers, wireless LAN devices, etc., and it is possible to realize a bio-radar that measures the distance and position of a living body at lower cost than when using an unmodulated signal.

[0054] These comprehensive or specific aspects may be realized as a system, an integrated circuit, a computer program, or a recording medium such as a computer-readable CD-ROM, or may be realized as any combination of an apparatus, a system, a method, an integrated circuit, a computer program, and a recording medium.

[0055] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. Note that each of the embodiments described below represents a preferred specific example of the present disclosure. The numerical values, shapes, materials, components, component placement and connection configurations, steps, and step order shown in the following embodiments are merely examples and are not intended to limit the present disclosure. Furthermore, among the components in the following embodiments, components that are not described in the independent claims that represent the highest concept of the present disclosure will be described as optional components that constitute a more preferred embodiment. Note that in this specification and drawings, components having substantially the same functional configuration will be assigned the same reference numerals to avoid redundant description.

[0056] (Embodiment 1) In embodiment 1, a method for detecting a living body will be described for a MIMO (Multiple Input Multiple Output) system in which both the transmitting antenna unit and the receiving antenna unit have multiple antenna elements. The method can also be similarly applied to a MISO (Multiple Input Single Output) system in which there are multiple transmitting antenna elements and a single receiving antenna element.

[0057] [Configuration of Estimation Apparatus 101] FIG. 1 is a block diagram showing an example of the configuration of an estimation apparatus according to the first embodiment.

[0058] The estimation device 101 shown in FIG. 1 includes a transmitting antenna unit 100, a transmitting unit 110, a transmission signal generating unit 120, a receiving antenna unit 130, a receiving unit 140, a matrix calculation unit 145, a biological correlation matrix calculation unit 180, and an estimation unit 190. The matrix calculation unit 145 includes a first complex transfer function calculation unit 150, a second complex transfer function calculation unit 160, and a third complex transfer function calculation unit 170. The estimation device 101 estimates the position of a biological organism 20. The estimation device 101 may estimate the position of the biological organism 20 in a target space, estimate the posture of the biological organism 20, determine whether the biological organism 20 exists in the target space, identify the biological organism 20 based on information (complex transfer function matrix) registered in advance for each individual biological organism 20, or estimate the movement of the biological organism 20.

[0059] [Transmitting Antenna Unit 100] The transmitting antenna unit 100 has M transmitting antenna elements. Here, M is a natural number equal to or greater than 1. In this embodiment, as described above, MIMO or MISO will be described, so M is a natural number equal to or greater than 2. As described above, the transmitting antenna elements transmit multicarrier signals (transmitting waves) generated by the transmitting unit 110, which will be described later.

[0060] [Transmission Signal Generator 120] The transmission signal generator 120 generates a multicarrier signal in which multiple subcarrier signals are modulated. Specifically, the transmission signal generator 120 generates multiple subcarrier signals corresponding to multiple subcarriers in different frequency bands, and multiplexes the generated multiple subcarrier signals to generate a multicarrier signal. In this embodiment, the transmission signal generator 120 generates an OFDM signal consisting of S subcarriers, which has high frequency band utilization efficiency, as the multicarrier signal. Note that the transmission signal generator 120 is not limited to generating an OFDM signal in which the subcarriers are orthogonal, as long as the multicarrier signal is obtained by multicarrier modulation. It is also possible to generate other multicarrier signals, such as a simple FDM (Frequency Division Multiplexing) signal.

[0061] Furthermore, the signal generated by the transmission signal generating unit 120 may be shared with a signal used for communication. That is, the transmission signal used for sensing the living body 20 may be used exclusively for sensing the living body 20, or may be used for both sensing the living body 20 and information communication.

[0062] [Transmitting Unit 110] The transmitting unit 110 performs appropriate processing on the signal generated by the transmitting signal generating unit 120 to generate a transmission wave. Examples of processing performed here include up-conversion, which converts the signal from an intermediate frequency (IF) frequency band to a radio frequency (RF) frequency band, and amplification, which amplifies the signal to an appropriate transmission level. The transmitting unit 110 outputs the processed multicarrier signal to the transmitting antenna unit 100, causing the transmitting antenna unit 100 to transmit the multicarrier signal. As a result, the multicarrier signal is transmitted from M transmitting antenna elements included in the transmitting antenna unit 100.

[0063] [Receiving Antenna Unit 130] The receiving antenna unit 130 has N receiving antenna elements. Here, N is a natural number equal to or greater than 1. In this embodiment, N is a natural number equal to or greater than 2 in the case of MIMO, and N is 1 in the case of MISO. The N receiving antenna elements receive signals (received signals 320, described later) transmitted from the M transmitting antenna elements and reflected by the living body 20.

[0064] [Receiving Unit 140] The receiving unit 140 observes the received signals 320 received by N receiving antenna elements, which include reflected signals resulting from the multicarrier signals transmitted from M transmitting antenna elements being reflected or scattered by the living organism 20, for a first period corresponding to a cycle derived from the activity of the living organism 20. The cycle derived from the activity of the living organism is a cycle derived from the living organism (biological fluctuation cycle) which is a time period equal to or longer than half the cycle of any one of the cycles of breathing, heartbeat, and body movement of the living organism 20.

[0065] The receiver 140 converts high-frequency signals received by the N receiving antenna elements into low-frequency signals that can be processed. The receiver 140 also has N amplifiers for amplifying the signals received by the N receiving antenna elements, respectively. That is, the N amplifiers correspond to the N receiving antenna elements, respectively. The receiver 140 then demodulates the OFDM signal into S subcarrier signals (IQ symbols).

[0066] The receiver 140 further calculates, from the plurality of IQ symbols observed in the first period, a plurality of complex transfer functions representing the propagation characteristics between the transmitting antenna element and the receiving antenna element for each subcarrier.

[0067] The receiver 140 may constantly monitor the received signal 320 received by the receiving antenna 130 and continuously or periodically output S low-frequency signals (IQ symbols).

[0068] The receiving unit 140 uses the plurality of received signals 320 observed during the first period to calculate, for each of N×M combinations of M transmitting antenna elements and N receiving antenna elements, a plurality of complex transfer functions representing propagation characteristics between the transmitting antenna elements and the receiving antenna elements in the combination, for each of a plurality of subcarriers to which a plurality of subcarrier signals respectively correspond. Note that the N×M combinations are all possible combinations when M transmitting antenna elements and N receiving antenna elements are combined one-to-one.

[0069] In this embodiment, the receiving unit 140 uses S subcarrier signals to calculate N×M×S sets of complex transfer functions representing propagation characteristics between each transmitting antenna element and each receiving antenna element for each of the S subcarrier signals. This allows the receiving unit 140 to generate a complex transfer function matrix having N×M×S elements. The calculated complex transfer function matrix also includes reflected waves that do not pass through the living body 20, such as direct waves and reflected waves from fixed objects.

[0070] The receiving unit 140 may constantly calculate the complex transfer function matrix by using each of the multiple subcarrier signals that are continuously or periodically output. With this configuration, when the estimating device 101 shares the hardware of a communication device, the complex transfer function matrix that is constantly calculated for use in processing by the communication device can also be used by the estimating device 101.

[0071] FIG. 2 is a diagram for explaining the relationship between a transmission signal, a channel, and a reception signal.

[0072] The transmission signal X transmitted from the transmitting antenna unit 100 propagates through the target space 30, is received by the receiving antenna unit 130, and is acquired as a received signal Y. The received signal Y received by the receiving antenna unit 130 is a signal that has changed as the transmission signal X propagates through the target space 30. Therefore, the received signal Y can be considered to be equal to a signal obtained by multiplying the propagation characteristic H of the target space 30 by the transmission signal X. The propagation characteristic H is expressed by the above-mentioned N×M×S set of complex transfer functions.

[0073] FIG. 3 is a diagram for explaining propagation characteristics at each timing of MIMO.

[0074] As described above, the propagation characteristics H have a complex transfer function for each combination of three types of parameters, i.e., for each receiving antenna element, each transmitting antenna element, and each subcarrier. That is, a different complex transfer function is calculated for each of a plurality of different receiving antenna elements, a different complex transfer function is calculated for each of a plurality of different transmitting antenna elements, and a different complex transfer function is calculated for each of a plurality of different subcarriers.

[0075] 3 shows an image of propagation characteristics H expressed by a combination of complex transfer functions when the number of receiving antenna elements is three, the number of transmitting antenna elements is four, and the number of subcarriers is two. In this case, the propagation characteristics H can be expressed as a combination of 3x4x2 blocks. One block represents one complex transfer function calculated for one specific receiving antenna element, one specific transmitting antenna element, and one specific subcarrier. In this way, the propagation characteristics H can be expressed three-dimensionally because it is expressed as a combination of three types of parameters: receiving antenna elements, transmitting antenna elements, and subcarriers. Furthermore, this three-dimensionally expressed propagation characteristics H is calculated for each of multiple timings. In other words, the propagation characteristics H are expressed as a complex transfer function matrix including, as elements of an NxMxS three-dimensional array, the complex transfer functions obtained for each of the S subcarriers and each of the NxM combinations.

[0076] In addition, with the subcarriers and transmitting antenna elements fixed, multiple complex transfer functions of different receiving antenna elements may be expressed as multiple complex transfer functions that differ in the receiving antenna element direction. Similarly, with the subcarriers and receiving antenna elements fixed, multiple complex transfer functions of different transmitting antenna elements may be expressed as multiple complex transfer functions that differ in the transmitting antenna element direction. Similarly, with the receiving antenna element and transmitting antenna element fixed, multiple complex transfer functions of different subcarriers may be expressed as multiple complex transfer functions that differ in the subcarrier direction. In this way, in the propagation characteristic H expressed three-dimensionally, the directions of each dimension may be expressed as the receiving antenna element direction, the transmitting antenna element direction, and the subcarrier direction using names related to three types of parameters.

[0077] For example, if the rows of a matrix representing the propagation characteristic H are assigned to the receiving antenna elements of the third order and the columns are assigned to the transmitting antenna elements, then different propagation characteristics H are calculated for each subcarrier and for each timing of acquiring the received signal. That is, in this embodiment, the receiving unit 140 calculates, from the S subcarrier signals transmitted from the receiving unit 140, the propagation characteristic H(t, s) between the M transmitting antenna elements and the N receiving antenna elements for the s-th subcarrier during the observation time t, which is expressed as a complex transfer function matrix as shown in Equation 1.

[0078]

[0079] [First Complex Transfer Function Calculation Unit 150] FIGS. 4 and 5 are diagrams schematically showing an example of the first error.

[0080] The first complex transfer function calculation unit 150 calculates, from the complex transfer function matrix, a first complex transfer function matrix in which a first error 210 corresponding to at least one of clock fluctuation between the transmitting unit 110 and the receiving unit 140, timing fluctuation in digital-to-analog conversion of the transmitting signal 310, and analog-to-digital conversion of the receiving signal 320 is suppressed. The receiving signal 320 includes a first error 210 that is random in time with respect to a direct wave + biological component 330 that includes the direct wave 200 and the biological component.

[0081] The first complex transfer function calculation unit 150 calculates N×M×S corrected elements by dividing all elements of the N×M×S complex transfer functions by direct wave components that are direct wave components extracted using one or more elements of the N×M×S complex transfer functions, which are sets of the complex transfer functions obtained for each of the S subcarriers and each of the N×M combinations, and that do not pass through the living body 20. In this way, the first complex transfer function calculation unit 150 generates a first complex transfer function matrix having N×M×S corrected elements.

[0082] Specifically, the first complex transfer function calculation unit 150 calculates an eigenvector for the complex transfer function by performing eigenvalue decomposition on the correlation matrix of the complex transfer function over a certain observation time or over the entire observation time, and calculates the first complex transfer function from the first eigenvector. Ｒ (s) and the correlation matrix R Ｔ (s) is calculated as in Equation 2 and Equation 3, respectively.

[0083]

[0084]

[0085] where t ０ represents the instantaneous observation time.

[0086] The first complex transfer function calculation unit 150 performs eigenvalue decomposition on the transmission correlation matrix and the reception correlation matrix to obtain the transmission first eigenvector v １ (s) and the first received eigenvector u １ When the s-th subcarrier is transmitted from the m-th transmitting antenna, the elements of the first complex transfer function received at the n-th receiving antenna are calculated using Equation 4.

[0087]

[0088] The first complex transfer function calculation unit 150 calculates this for different elements in all subcarrier directions, transmitting antenna element directions, and receiving antenna element directions, and calculates a first complex transfer function matrix including the calculated multiple elements.

[0089] In this embodiment, the case where there are two or more receiving antenna elements has been described, but when there is one receiving antenna element, Equation 1 may use a matrix in the transmitting antenna element direction and the subcarrier direction.

[0090] In this embodiment, the case where there are two or more transmitting antenna elements has been described, but when there is one transmitting antenna element, the first error may be suppressed by dividing each element by the average value of adjacent subcarriers.

[0091] As described above, the direct wave component may be a channel component of a direct wave calculated by multiplying a complex transfer function by an eigenvector pair having the largest eigenvalue among pairs of eigenvalues ​​and eigenvectors calculated by eigenvalue decomposition of N×M×S complex transfer functions. The direct wave component may be any one of the N×M×S complex transfer functions, or an average of the N×M×S complex transfer functions. The direct wave component may be a channel component of a direct wave calculated by multiplying a complex transfer function by left singular vectors and right singular vectors calculated by singular value decomposition of the N×M×S complex transfer functions.

[0092] [Second Complex Transfer Function Calculation Unit 160] FIGS. 6 and 7 are diagrams schematically showing an example of the second error.

[0093] In this embodiment, the second complex transfer function calculation unit 160 performs a predetermined process to suppress the second error 400, which is an error within the receiver, using the amplitude average of multiple first elements arranged in the first dimension direction 500 from the first complex transfer function calculation unit 150. In this embodiment, the second complex transfer function calculation unit 160 calculates a second complex transfer function matrix in which the second error 400 is suppressed, based on the amplitude average of multiple first elements in the transmitting antenna element direction as the first dimension direction 500. Among the elements of the second complex transfer function matrix, the elements of the second complex transfer function matrix when the s-th subcarrier is transmitted from the m-th transmitting antenna and received by the n-th receiving antenna are expressed by Equation 5.

[0094]

[0095] As shown in FIG. 7 , the signal amplified by the receiver 140 includes a second error due to the amplification process as an internal receiver error. The second error appears at the same timing and with the same amplitude regardless of the transmitting antenna element or subcarrier. Therefore, by calculating the average amplitude of multiple first elements derived from the received signal received by the same receiving antenna element, it is possible to extract noise components common to these multiple first elements. Then, by dividing each of the multiple first elements by the extracted noise components, it is possible to calculate elements from which the noise components have been removed.

[0096] The second complex transfer function calculation unit 160 calculates this for different elements in all subcarrier directions, transmitting antenna element directions, and receiving antenna element directions, and calculates a second complex transfer function matrix including the calculated multiple elements.

[0097] In this way, the second complex transfer function calculating unit 160 calculates the second complex transfer function matrix by performing a predetermined process on each of the N×M×S elements in the first complex transfer function matrix, which includes the complex transfer functions obtained for each of the S subcarriers and each of the N×M combinations as elements of an N×M×S three-dimensional array. The predetermined process is a process of calculating an amplitude average of multiple first elements including the element to be processed and dividing the element to be processed by the amplitude average. The multiple first elements are included in the S×M elements obtained for one receiving antenna element corresponding to the element to be processed.

[0098] In this embodiment, the amplitude average of multiple first elements arranged in the transmitting antenna element direction of the first complex transfer function matrix is ​​used to calculate the second complex transfer function matrix, but the amplitude average of multiple first elements in the subcarrier direction or both may also be used. That is, the multiple first elements for calculating the amplitude average may be M elements obtained for one receiving antenna element corresponding to the element to be processed and one subcarrier corresponding to the element to be processed. Also, the multiple first elements for calculating the amplitude average may be S elements obtained for one receiving antenna element corresponding to the element to be processed and one transmitting antenna element corresponding to the element to be processed. Also, the multiple first elements for calculating the amplitude average may be S × M elements obtained for one receiving antenna element corresponding to the element to be processed.

[0099] In addition, although the second complex transfer function matrix is ​​calculated using the amplitude average of a plurality of first elements in this embodiment, it may be calculated using the phase average of a plurality of first elements or the average value of both. In other words, the second complex transfer function matrix may have a plurality of elements obtained by dividing each element of the first complex transfer function matrix by the phase average of a plurality of first elements or the average value of both.

[0100] In this embodiment, the amplitude average uses all of the multiple first elements for averaging the amplitude of the first complex transfer function in the transmitting antenna element direction or the subcarrier direction. However, it is also possible to use the average value of some (i.e., any number (two or more)) of the multiple first elements aligned in the transmitting antenna direction based on the element to be processed, or the multiple first elements aligned in the subcarrier direction based on the element to be processed, or the multiple first elements aligned in a plane in the transmitting antenna direction and the subcarrier direction based on the element to be processed.

[0101] In the present embodiment, the second complex transfer function matrix is ​​calculated based on the first complex transfer function matrix after the first complex transfer function matrix is ​​calculated, but the order of calculation may be reversed, i.e., the first complex transfer function matrix may be calculated based on the second complex transfer function matrix after the second complex transfer function matrix is ​​calculated.

[0102] [Third Complex Transfer Function Calculation Section 170] FIG. 8 is a diagram schematically illustrating an example of the third error, and FIG. 9 is a diagram schematically illustrating the relationship between the third error and the channel.

[0103] The third complex transfer function calculation unit 170 receives the channel 630 obtained by measurement or the calculated second complex transfer function, and calibrates (corrects) the third error 610, which is the phase error in the frequency direction. The phase error in the frequency direction is the phase error between multiple signals having different frequencies. The phase error that requires calibration will be described with reference to FIG. 9 .

[0104] When signals of different frequencies propagate through space and are received, the amount of phase rotation of the transmitted signal 310 relative to the received signal 320 varies depending on the frequency and the distance between the transmitting antenna unit 100 and the receiving antenna unit 130 (hereinafter referred to as the antenna distance). The three transmitted waves 750-A, 750-B, and 750-C in FIG. 9 are signals of different frequencies transmitted from the transmitting antenna unit 100 with the same phase, and it can be seen that the phases become more different as the propagation distance increases (760-B, 760-C). Therefore, the antenna distance can be calculated by transmitting and receiving signals of multiple known frequencies and measuring the phase difference. However, the actually measured phase difference includes not only the influence of spatial propagation between the transmitting antenna unit 100 and the receiving antenna unit 130, but also an error (hereinafter referred to as the third error 610) due to the influence of the phase characteristics of the internal circuits, antennas, etc. of the transmitter and receiver. Therefore, in order to accurately measure the antenna distance, it is necessary to remove the third error 610 from the observed signal.

[0105] The third error 610 is the channel h obtained in the measurement. ｍｅａｓ and an ideal channel h, which is a spatial channel that can be calculated from the second complex transfer function and the distance between the transmitting antenna element and the receiving antenna element. ｉｄｅａｌ This is not limited to the estimation of the distance between the antennas, but also applies to the case of estimating the distance between the estimation device 101 and the living body 20.

[0106] The third complex transfer function calculation unit 170 corrects a third error 610, which is a phase error in the subcarrier direction. A direct wave component is extracted from the second complex transfer function received from the second complex transfer function calculation unit 160. Methods for determining a biological component from a complex transfer function recorded in time series include the Fourier transform disclosed in Patent Document 1 and a method using difference information disclosed in Patent Document 2.

[0107] In a method using a Fourier transform, for example, the third complex transfer function calculation unit 170 performs a Fourier transform on the second complex transfer function with respect to the observation time (slow time) to extract only specific frequency components, thereby calculating a complex transfer function corresponding to the direct wave 200. The third complex transfer function calculation unit 170 extracts an arbitrary frequency component, for example, a frequency component of 0 Hz, from the frequency response complex transfer function calculated by performing a Fourier transform on the second complex transfer function with respect to the observation time, and calculates a time response complex transfer function corresponding to the direct wave 200 by performing an inverse Fourier transform on the frequency response complex transfer function corresponding to the direct wave 200.

[0108] Next, the third complex transfer function calculation unit 170 calculates H , which is an ideal channel 600 between the antenna elements, based on the antenna distance 620 between the transmitting antenna element and the receiving antenna element that has been input in advance. ｉｄｅａｌ The input inter-antenna distance d is a value obtained by, for example, actually measuring the distance between the transmitting antenna element and the receiving antenna element by a user. Here, H ｉｄｅａｌ is a complex matrix having elements of the number S of subcarriers, and is the ideal channel 600 of the s-th subcarrier, H ｉｄｅａｌ (s) is calculated using Equation 6.

[0109]

[0110] Here, d ｎｍ denotes the distance between the mth transmitting antenna and the nth receiving antenna, and k(s) denotes the wave number of the sth subcarrier. ｉｄｅａｌ is an ideal complex transfer function between the transmitting and receiving antenna elements obtained based on the inter-antenna distance 620 between the transmitting and receiving antenna elements.

[0111] Next, the third complex transfer function calculation unit 170 calculates the ideal channel 600, H ｉｄｅａｌ and the time response complex transfer function H corresponding to the direct wave 200. ０ The third complex transfer function calculation unit 170 calculates a correction value for correcting a third error 610, which is a phase error in the subcarrier direction, based on the ideal channel 600, H ｉｄｅａｌ and the time response complex transfer function H corresponding to the direct wave 200. ０ The correction value H ｃａｌ A correction value h of the third error 610 between the mth transmitting antenna element and the nth receiving antenna element in the sth subcarrier is calculated. ｃａｌ＿ｎｍ is calculated using Equation 7.

[0112]

[0113] Finally, the third complex transfer function calculation unit 170 calculates the correction value H ｃａｌ The third complex transfer function matrix is ​​calculated based on the following equation: The third complex transfer function between the mth transmitting antenna element and the nth receiving antenna element in the sth subcarrier is calculated by equation 8.

[0114]

[0115] The third complex transfer function calculation unit 170 calculates this for different elements in all subcarrier directions, transmitting antenna element directions, and receiving antenna element directions, and calculates a third complex transfer function matrix including the calculated multiple elements.

[0116] In this way, the third complex transfer function calculating unit 170 calculates an offset value (correction value) with respect to a reference phase calculated from the positional relationship between the transmitting antenna unit 100 and the receiving antenna unit 130, and calculates a third complex transfer function matrix by correcting the second complex transfer function matrix based on the offset value. Specifically, the third complex transfer function calculating unit 170 converts the second complex transfer function matrix into a frequency response matrix or a frequency response vector, and extracts a frequency response matrix or a frequency response vector corresponding to a direct wave between the transmitting antenna unit 100 and the receiving antenna unit 130. The third complex transfer function calculating unit 170 calculates an ideal complex transfer function corresponding to the direct wave, and calculates, as offset values, correction values ​​for correcting phase errors in S second elements for each N × M combination of the second complex transfer function matrix based on the ideal complex transfer function and the frequency response matrix or the frequency response vector. The third complex transfer function calculating unit 170 calculates a third complex transfer function matrix in which the phase errors have been corrected based on the correction values.

[0117] In this embodiment, the time response complex transfer function H corresponding to the direct wave 200 is ０ Although it has been stated that is calculated by Fourier transform, it may be calculated using the high-speed processing method disclosed in Patent Document 2, which does not require Fourier transform.

[0118] In this embodiment, the time response complex transfer function H corresponding to the direct wave 200 is ０ is calculated by Fourier transform, but the element h of the time response complex transfer function ０＿ｎｍ (s) is the element h'' of the second complex transfer function matrix ｎｍThe offset value may be calculated by sorting any range of real and imaginary components in (t, s), for example, sorting the real and imaginary components in ascending order (or descending order), extracting 10% to 90% values ​​of the sorted components, averaging them in the time direction, and dividing the elements of the second complex transfer function matrix by the calculated average value. That is, the third complex transfer function calculation unit 170 calculates average values ​​by averaging all elements or multiple third elements of the second complex transfer function matrix in the real part direction and the imaginary part direction, respectively. The third complex transfer function calculation unit 170 calculates an ideal complex transfer function corresponding to a direct wave between the transmitting antenna unit 100 and the receiving antenna unit 130, and calculates, as the offset value, a correction value for correcting phase errors in S second elements for each N × M combination of the second complex transfer function matrix based on the ideal complex transfer function and the calculated average value. The third complex transfer function calculation unit 170 calculates a third complex transfer function matrix in which the phase errors have been corrected based on the correction value.

[0119] Here, the third complex transfer function calculating unit 170 may further use a Minimum Mean Square Error (MMSE) filter that emphasizes the direct wave component as a reference signal using an adaptive array based on MMSE with respect to the time direction of the calculated third complex transfer function. That is, the third complex transfer function calculating unit 170 may calculate the fourth complex transfer function matrix by applying a time direction MMSE filter in which the direct wave between the transmitting antenna unit 100 and the receiving antenna unit 130 is set as a reference signal to the second complex transfer function matrix or the third complex transfer function matrix.

[0120] In this embodiment, a method for calculating a correction value from the measurement results of a complex transfer function has been described. However, if the correction value does not change over time, a value measured using a measuring instrument such as a network analyzer in a factory or the like and stored in memory may be used as the correction value.

[0121] [Biophysical correlation matrix calculation unit 180] The biophysical correlation matrix calculation unit 180 sequentially records, for each of the plurality of subcarriers and for each of the N × M combinations, the plurality of complex transfer function matrices calculated by the third complex transfer function calculation unit 170 in a time series that is the order in which the plurality of received signals 320 were observed. Then, the biophysical correlation matrix calculation unit 180 extracts components related to the biophysical organism 20 from the third complex transfer function matrix or the fourth complex transfer function matrix that is observed during a first period sequentially recorded in time series and in which the first error 210, the second error 400, and the third error 610 are suppressed, for each of the plurality of subcarriers and for each of the N × M combinations, thereby calculating, for each of the plurality of subcarriers, a biophysical component transfer function matrix expressed by an N × M-dimensional matrix.

[0122] Here, the biological component transfer function matrix is ​​obtained by extracting reflected waves or scattered waves (biological components) that have passed through the living body 20 and are included in the received signal 320. Methods for determining the biological components from the third complex transfer function recorded in time series include the Fourier transform disclosed in Patent Document 1 and a method using difference information disclosed in Patent Document 2.

[0123] For example, in a method using a Fourier transform, the third complex transfer function matrix is ​​Fourier transformed with respect to the observation time (slow time) to extract only specific frequency components, thereby making it possible to calculate a biological component transfer function matrix for each of a plurality of frequency components that may include the influence of biological activity, for example, those included in the range from 0.1 Hz to 3 Hz.

[0124] The relationship between frequency and phase of the biological component transfer function matrix is ​​shown in Figure 10. The solid line 800 represents how the phase of each component of the biological component transfer function matrix varies with the subcarrier frequency when the biological component 20 is located at a certain position. As the biological component 20 approaches the transmitting antenna unit 100 or the receiving antenna unit 130 from the above position, the path length of the radio waves reflected by the biological component 20 shortens, causing the slope of the graph to become gentler, as shown by the dashed line 810. In principle, the ToF or the distance to the biological component can be estimated from the slope of this graph. Specifically, this biological component transfer function matrix is ​​further inverse Fourier transformed in the subcarrier direction to obtain a time-domain biological component transfer function matrix, which determines the time from when the signal containing the biological component is transmitted from the transmitting antenna to when it is received by the receiver.

[0125] Fig. 11 shows the relationship between time (column direction of the matrix) and phase of the time-domain biological component transfer function matrix. The phase changes of the solid line 800 and dashed line 810 in Fig. 10 appear as peaks indicated by the solid line 910 and dashed line 920, respectively. However, the time resolution Δt calculated here is expressed by Equation 9 using the subcarrier bandwidth B.

[0126]

[0127] For example, when the bandwidth is 20 MHz, the time resolution is equivalent to 0.5 μs, which is converted into a distance resolution of approximately 15 m, which is not practical.

[0128] Therefore, in this embodiment, the MUSIC method is used to improve the resolution. In order to use the MUSIC method, the biometric correlation matrix calculation unit 180 calculates a biometric correlation matrix R of the biometric component transfer function vector obtained by vectorizing the biometric component transfer function matrix. ｆ is calculated according to the following formula 10.

[0129]

[0130] [Estimation unit 190] The estimation unit 190 estimates the biometric correlation matrix R calculated by the biometric correlation matrix calculation unit 180. ｆ In other words, the estimation unit 190 performs distance and angle measurement using the biological correlation matrix R ｆ is decomposed into eigenvalues, and a vector U Ｓ and the eigenvector U corresponding to the noiseＮ Here, the eigenvectors corresponding to the signal are vectors that are ordered from the first eigenvector up to the number of detection targets, and if there is one target, for example, there is only the first eigenvector. Furthermore, if there are k targets (k is a natural number equal to or greater than 2), the eigenvectors corresponding to the signal are k eigenvectors from the first eigenvector to the k-th eigenvector. Furthermore, the eigenvectors corresponding to noise refer to eigenvectors other than the eigenvector corresponding to the signal.

[0131] Using the eigenvectors obtained as above, the MUSIC spectrum P ＭＵＳＩＣ Calculate (x, y).

[0132]

[0133] Here, a(x, y) represents the steering vector, which is calculated as shown in Equation 12.

[0134]

[0135] Here, d ｎｍ (x, y) represents the sum of the distance between the coordinates (x, y) and the nth transmitting antenna element and the distance between the coordinates (x, y) and the mth receiving antenna element, and λ(s) represents the wavelength of the sth subcarrier. The MUSIC spectrum P ＭＵＳＩＣ The position (x, y) at which the maximum value is obtained is estimated to be the position of the living body 20 .

[0136] In this embodiment, the estimation unit 190 performs averaging in the frequency direction of biological activity in Equation 10, but may also perform averaging in the subcarrier frequency direction.

[0137] In this embodiment, the estimation unit 190 may estimate the first angle θ from the receiving antenna to the living body by applying a steering vector calculated using an arbitrary subcarrier frequency according to Equation 12 to the MUSIC method of Equation 11.

[0138] In addition, in this embodiment, the estimation unit 190 estimates the position of the living body 20, but it may estimate the distance between the estimation device 101 and the living body 20. When any one transmitting antenna element and any one receiving antenna element are extracted, P ＭＵＳＩＣ The maximum value of (x, y) is an ellipse 1010 with the transmitting antenna element and the receiving antenna element as foci, as shown in Fig. 12. The sum (third distance) of a distance a (first distance) between the transmitting antenna element and the living body 20 from any point (x, y) on the ellipse 1010 where the transmitting and receiving antennas become the maximum, and a distance b (second distance) between the receiving antenna element and the living body 20 is calculated by Equation 13.

[0139]

[0140] where a(l) represents the steering vector, which is calculated as shown in Equation 14.

[0141]

[0142] The MUSIC spectrum P thus obtained ＭＵＳＩＣ The maximum value of (l) corresponds to the sum (third distance) of the distance a (first distance) between the transmitting antenna unit 100 and the living body 20 in Figure 12 and the distance b (second distance) between the receiving antenna unit 130 and the living body 20.

[0143] Fig. 12 is a schematic diagram showing the positional relationship between a living body, a transmitting antenna unit, and a receiving antenna unit in MIMO, and the position of the living body. In Fig. 12, the transmitting antenna unit 100 has multiple transmitting antenna elements, and the receiving antenna unit 130 has multiple receiving antenna elements. In other words, Fig. 12 is an example of MIMO.

[0144] In this way, the estimation unit 190 uses the biological correlation matrix calculated for each of the multiple subcarriers to estimate a third distance, which is the sum of the first distance between the transmitting antenna unit 100 and the biological body 20 and the second distance between the receiving antenna unit 130 and the biological body 20.

[0145] In this embodiment, the estimation unit 190 estimated the position of the living body using equation 13, but the sum of the estimated distance a (first distance) between the transmitting antenna unit 100 and the living body 20 and the distance b (second distance) between the receiving antenna unit 130 and the living body 20 may be set as a third distance L, and the position of the living body 20 may be estimated using the first angle θ as shown in equation 16.

[0146]

[0147] The coordinates (x, y) of the living body 20 are calculated using the first distance a and the first angle θ by the following equation.

[0148]

[0149] As will be described later, the estimation unit 190 may estimate the position of the living body 20 from the second angle φ as shown in Equation 32, using the sum of the estimated distance a (first distance) between the transmitting antenna unit 100 and the living body 20 and the distance b (second distance) between the receiving antenna unit 130 and the living body 20 as a third distance L.

[0150] Similarly, the estimation unit 190 may select one antenna from multiple transmitting antenna elements as shown in Figure 13, and calculate the sum (third distance) of the distance a (first distance) between the transmitting antenna unit 100 and the living body 20 and the distance b (second distance) between the receiving antenna unit 130 and the living body 20 as shown in Equation 13.

[0151] Fig. 13 is a schematic diagram showing the positional relationship between a living body, a transmitting antenna unit, and a receiving antenna unit in MISO, and the position of the living body. In Fig. 13, the transmitting antenna unit 100 has multiple transmitting antenna elements, and the receiving antenna unit 130 has one receiving antenna element. In other words, Fig. 13 is an example of MISO.

[0152] The MUSIC spectrum P thus obtained ＭＵＳＩＣThe maximum value of (l) corresponds to the sum (third distance) of the distance a (first distance) between the transmitting antenna unit 100 and the living body 20 and the distance b (second distance) between the receiving antenna unit 130 and the living body 20 in Fig. 13. In this way, the estimation unit 190 estimates the third distance, which is the sum of the first distance between the transmitting antenna unit 100 and the living body 20 and the second distance between the receiving antenna unit 130 and the living body 20, using the living body correlation matrix calculated for each of the multiple subcarriers.

[0153] In this embodiment, the estimation unit 190 estimated the position of the living body 20 using equation 13, but the position of the living body 20 may also be estimated from the first angle θ as shown in equation 16, where L is a third distance, which is the sum of the estimated distance a (first distance) between the transmitting antenna unit 100 and the living body 20 and the distance b (second distance) between the receiving antenna unit 130 and the living body 20.

[0154] [Operation of Estimation Device 101] The operation of the estimation process of the estimation device 101 configured as above will be described.

[0155] FIG. 14 is a flowchart showing the estimation process of the estimation device according to the first embodiment.

[0156] The estimation device 101 calculates a complex transfer function for a first period (S100).

[0157] Next, the estimation device 101 calculates a first complex transfer function matrix that suppresses a first error 210 corresponding to at least one of the clock fluctuation between the transmitting unit 110 and the receiving unit 140, and the timing fluctuation of the digital-to-analog conversion of the transmitting signal 310 or the analog-to-digital conversion of the receiving signal 320 (S200).

[0158] Next, the estimation device 101 calculates a second complex transfer function matrix in which the second error 400, which is a reception internal error, is suppressed (S300).

[0159] Next, the estimation apparatus 101 calculates a third complex transfer function matrix in which the third error 610, which is the phase error in the subcarrier direction, is suppressed (S400).

[0160] Finally, the estimation device 101 performs processing to estimate the direction, distance, and / or position of the living body 20 (S500).

[0161] Details of the processing of each step are omitted here because they are included in the description of the configuration of the estimation device 101.

[0162] [Effects, etc.] Estimation device 101 according to this embodiment is a device for estimating a reception internal error, and includes a transmission signal generation unit 120, a transmission antenna unit 100, a transmission unit 110, a reception antenna unit 130, a reception unit 140, and a matrix calculation unit 145. The transmission signal generation unit 120 generates a multicarrier signal in which S (S is a natural number greater than or equal to 2) subcarrier signals are modulated. The transmission antenna unit 100 has M (M is a natural number greater than or equal to 1) transmission antenna elements. The transmission unit 110 processes the multicarrier signal and outputs it to the transmission antenna unit 100, thereby causing the transmission antenna unit 100 to transmit the multicarrier signal. The reception antenna unit 130 has N (N is a natural number greater than or equal to 1) reception antenna elements. The receiving unit 140 observes, for a first period corresponding to a cycle resulting from the activity of the living body 20, received signals received by each of the N receiving antenna elements, the received signals including reflected signals resulting from the multicarrier signals transmitted from each of the M transmitting antenna elements being reflected or scattered by the living body 20. The receiving unit 140 uses the plurality of received signals observed during the first period to calculate, for each of N×M combinations of each of the M transmitting antenna elements and each of the N receiving antenna elements, a plurality of complex transfer functions representing propagation characteristics between the transmitting antenna element and the receiving antenna element in the combination, for each of the S subcarriers to which the S subcarrier signals correspond. The matrix calculation unit 145 calculates a second complex transfer function matrix by performing a predetermined process on each of the N×M×S elements of a first complex transfer function matrix including the complex transfer functions obtained for each of the S subcarriers and each of the N×M combinations as elements of an N×M×S three-dimensional array. The predetermined processing is processing of calculating an amplitude average of a plurality of first elements including a target element to be processed, and dividing the target element by the amplitude average, where the plurality of first elements are included in S×M elements obtained for one receiving antenna element corresponding to the target element to be processed.

[0163] According to this, a predetermined process of calculating an amplitude average of a plurality of first elements that are included in the S×M elements obtained for one receiving antenna element corresponding to the element to be processed and that include the element to be processed, and dividing the element to be processed by the amplitude average is performed for each of the N×M×S elements in the first complex transfer function matrix, so that it is possible to reduce the first error that is imparted to the received signal by each receiving antenna element. Thus, it is possible to estimate the position of the living body 20 with high accuracy.

[0164] Furthermore, in the estimation device 101 according to this embodiment, the multiple first elements are M elements obtained for one receiving antenna element corresponding to the element to be processed and one subcarrier corresponding to the element to be processed.

[0165] Therefore, the first error can be reduced by using the amplitude average of M elements obtained for one receiving antenna element corresponding to the element to be processed and one subcarrier corresponding to the element to be processed.

[0166] Furthermore, in the estimation device 101 according to this embodiment, the multiple first elements are S elements obtained for one receiving antenna element corresponding to the element to be processed and one transmitting antenna element corresponding to the element to be processed.

[0167] Therefore, the first error can be reduced by using the amplitude average of S elements obtained for one receiving antenna element corresponding to the element to be processed and one transmitting antenna element corresponding to the element to be processed.

[0168] In the estimation device 101 according to this embodiment, the plurality of first elements are S×M elements.

[0169] Therefore, the first error can be reduced by using the amplitude average of the S×M elements.

[0170] Furthermore, in the estimation device 101 according to this embodiment, the matrix calculation unit 145 further calculates an offset value with respect to a reference phase calculated from the positional relationship between the transmitting antenna unit 100 and the receiving antenna unit 130, and calculates a third complex transfer function matrix by correcting the second complex transfer function matrix based on the offset value.

[0171] This makes it possible to reduce the third error with respect to the reference phase, and therefore to estimate the position of the living body 20 with higher accuracy.

[0172] Furthermore, in the estimation device 101 according to this embodiment, the matrix calculation unit 145 converts the second complex transfer function matrix into a frequency response matrix or a frequency response vector, and extracts the frequency response matrix or the frequency response vector corresponding to the direct wave between the transmitting antenna unit 100 and the receiving antenna unit 130. The matrix calculation unit 145 calculates an ideal complex transfer function corresponding to the direct wave, and calculates, as offset values, correction values ​​for correcting phase errors in S second elements for each of the N×M combinations of the second complex transfer function matrix, based on the ideal complex transfer function and the frequency response matrix or the frequency response vector. The matrix calculation unit 145 calculates a third complex transfer function matrix in which the phase errors have been corrected based on the correction values.

[0173] Therefore, phase errors in the subcarrier direction can be eliminated, and the distance from the estimation device 101 to the living body 20 can be measured with higher accuracy.

[0174] Furthermore, in the estimation device 101 according to this embodiment, the matrix calculation unit 145 calculates an average value by averaging all elements or multiple third elements of the second complex transfer function matrix in the real part direction and the imaginary part direction, respectively. The matrix calculation unit 145 calculates an ideal complex transfer function corresponding to a direct wave between the transmitting antenna unit 100 and the receiving antenna unit 130, and calculates, as offset values, correction values ​​for correcting phase errors in S second elements for each of the N×M combinations of the second complex transfer function matrix based on the ideal complex transfer function and the average value. The matrix calculation unit 145 calculates a third complex transfer function matrix in which the phase errors have been corrected based on the correction values.

[0175] Therefore, phase errors in the subcarrier direction can be eliminated, and the distance from the estimation device 101 to the living body 20 can be measured with higher accuracy.

[0176] Furthermore, in the estimation device 101 according to this embodiment, the matrix calculation unit 145 further calculates a fourth complex transfer function matrix by applying a time-direction MMSE (Minimum Mean Square Error) filter, in which a direct wave between the transmitting antenna unit 100 and the receiving antenna unit 130 is set as a reference signal, to the second complex transfer function matrix or the third complex transfer function matrix.

[0177] Therefore, phase errors in the subcarrier direction can be eliminated, and the distance from the estimation device 101 to the living body 20 can be measured with higher accuracy.

[0178] Furthermore, in the estimation device 101 according to this embodiment, the first complex transfer function matrix has N×M×S corrected elements obtained by dividing all elements of the N×M×S complex transfer functions by direct wave components that do not pass through the living body 20, and are direct wave components extracted using one or more elements of N×M×S complex transfer functions, which are a set of complex transfer functions obtained for each of the S subcarriers and each of the N×M combinations.

[0179] This makes it possible to reduce the first error, which is a component corresponding to at least one of (1) clock fluctuation between a transmitter consisting of a transmission signal generation unit and a transmission unit that transmits from a transmission antenna unit, and a receiver consisting of a reception unit that receives by a reception antenna unit, and (2) timing fluctuation of digital-to-analog conversion of a transmission signal or analog-to-digital conversion of a reception signal. Therefore, it is possible to estimate the position of the living body 20 with higher accuracy.

[0180] Furthermore, in the estimation device 101 according to this embodiment, M and N are equal to or greater than 2. The estimation device 101 further includes an estimation unit 190. The estimation unit 190 uses the third complex transfer function matrix calculated by the matrix calculation unit 145 to estimate the position of the living body 20 from a first angle that is the direction of the living body 20 as seen from the M transmitting antenna units 100 and a second angle that is the direction of the living body 20 as seen from the N receiving antenna units 130.

[0181] Therefore, the position of the living body 20 relative to the estimation device 101 can be estimated with higher accuracy.

[0182] Furthermore, in the estimation device 101 according to this embodiment, M is 2 or greater, and N is 1. The estimation device 101 further includes an estimation unit 190. The estimation unit 190 uses the third complex transfer function matrix calculated by the matrix calculation unit 145 to estimate a third distance that is the sum of the first distance between the transmitting antenna unit 100 and the living body 20 and the second distance between the receiving antenna unit 130 and the living body 20, estimates a first angle that is the direction of the living body 20 as seen from the transmitting antenna unit 100, and estimates the position of the living body 20 from the third distance and the first angle.

[0183] Therefore, the position of the living body 20 relative to the estimation device 101 can be estimated with higher accuracy.

[0184] In the estimation device 101 according to this embodiment, the estimation unit 190 estimates the first distance, the second distance, the first angle, and the second angle using any one of the MUSIC (Multiple Signal Classification) method, the beamformer method, and the Capon method.

[0185] Therefore, the distance to the living body 20 based on the estimation device 101 can be estimated with higher accuracy.

[0186] In this way, according to this embodiment, it is possible to use an estimation device 101 with a MIMO or MISO configuration to estimate the position (coordinates) of the living body 20, the distance between the transmitting antenna unit 100 and the receiving antenna unit 130 and the living body 20, and the direction (angle) in which the living body 20 is located relative to the transmitting antenna unit 100 and the receiving antenna unit 130.

[0187] As described above, according to the present disclosure, it is possible to realize an estimation device, an estimation method, and a program that can estimate the distance and position of a living body using a wireless signal in a short time and with high accuracy.

[0188] (Embodiment 2) In embodiment 2, a method for detecting a living body will be described for a SIMO (Single Input Multiple Output) system in which a single transmitting antenna and multiple receiving antennas are used. The method can also be similarly applied to a SISO (Single Input Single Output) system in which both the transmitting antenna and the receiving antenna are single.

[0189] [Configuration of Estimation Apparatus 1201] FIG. 15 is a block diagram showing an example of the configuration of the estimation apparatus 1201 according to the second embodiment.

[0190] 15 includes a transmitting antenna unit 1200, a transmitting unit 1210, a transmitting signal generating unit 1220, a receiving antenna unit 1230, a receiving unit 1240, a matrix calculating unit 1245, a biological correlation matrix calculating unit 1280, and an estimating unit 1290. The matrix calculating unit 1245 includes a first complex transfer function calculating unit 1250, a second complex transfer function calculating unit 1260, and a third complex transfer function calculating unit 1270. The estimating device 1201 estimates the position of a living body 20.

[0191] [Transmitting Antenna Unit 1200] The transmitting antenna unit 1200 has one transmitting antenna element. As described above, the transmitting antenna element transmits a multicarrier signal (transmitting wave) generated by a transmitting unit 1210 (described later).

[0192] [Transmission Signal Generator 1220] The transmission signal generator 1220 generates a multicarrier signal in which multiple subcarrier signals are modulated. Specifically, the transmission signal generator 1220 generates multiple subcarrier signals corresponding to multiple subcarriers in different frequency bands, and multiplexes the generated multiple subcarrier signals to generate a multicarrier signal. In this embodiment, the transmission signal generator 1220 generates an OFDM signal consisting of S subcarriers, which has high frequency band utilization efficiency, as the multicarrier signal. Note that the transmission signal generator 1220 is not limited to generating an OFDM signal in which the subcarriers are orthogonal, as long as the multicarrier signal is obtained by multicarrier modulation. It is also possible to generate other multicarrier signals, such as a simple FDM (Frequency Division Multiplexing) signal.

[0193] Furthermore, the signal generated by the transmission signal generating unit 1220 may be used in common with a signal used for communication. That is, the transmission signal used for sensing the living body 20 may be used exclusively for sensing the living body 20, or may be used for both sensing the living body 20 and information communication.

[0194] [Transmitting Unit 1210] The transmitting unit 1210 performs appropriate processing on the signal generated by the transmitting signal generating unit 1220 to generate a transmission wave. Examples of processing performed here include up-conversion, which converts the signal from the IF (Intermediate Frequency) frequency band to the RF (Radio Frequency) frequency band, and amplification, which amplifies the signal to an appropriate transmission level. The transmitting unit 1210 outputs the processed multicarrier signal to the transmitting antenna unit 1200, causing the transmitting antenna unit 1200 to transmit the multicarrier signal. As a result, the multicarrier signal is transmitted from one transmitting antenna element included in the transmitting antenna unit 1200.

[0195] [Receiving Antenna Unit 1230] The receiving antenna unit 1230 has N receiving antenna elements. Here, N is a natural number equal to or greater than 1. In this embodiment, N is a natural number equal to or greater than 2 in the case of SIMO, and N is 1 in the case of SISO. The N receiving antenna elements receive a signal (received signal 320) transmitted from one transmitting antenna element and reflected by the living body 20.

[0196] [Receiving Unit 1240] The receiving unit 1240 observes the received signals 320 received by N receiving antenna elements, which include a reflected signal resulting from reflection or scattering of a multicarrier signal transmitted from one transmitting antenna element by the living organism 20, for a first period corresponding to a cycle derived from the activity of the living organism 20. The cycle derived from the activity of the living organism is a cycle derived from the living organism (biological fluctuation cycle) which is a time period equal to or longer than half the cycle of any one of the cycles of breathing, heartbeat, and body movement of the living organism 20.

[0197] The receiver 1240 converts high-frequency signals received by the N receiving antenna elements into low-frequency signals that can be processed. The receiver 1240 also amplifies the signals received by the N receiving antenna elements. The receiver 1240 then demodulates the OFDM signal into S subcarrier signals (IQ symbols).

[0198] The receiver 1240 further calculates, from the plurality of IQ symbols observed in the first period, a plurality of complex transfer functions representing the propagation characteristics between the transmitting antenna element and the receiving antenna element for each subcarrier.

[0199] The receiver 1240 may constantly monitor the received signal 320 received by the receiving antenna 1230 and continuously or periodically output S low-frequency signals (IQ symbols).

[0200] The receiving unit 1240 uses the multiple received signals 320 observed during the first period to calculate multiple complex transfer functions representing the propagation characteristics between the transmitting antenna element and the receiving antenna element in each of a total of N combinations of one transmitting antenna element and N receiving antenna elements, for each of the multiple subcarriers to which the multiple subcarrier signals respectively correspond.

[0201] The receiving unit 1240 calculates S×N sets of complex transfer functions representing propagation characteristics between each transmitting antenna element and each receiving antenna element for the estimation device 1201. As a result, the receiving unit 1240 may generate a complex transfer function matrix having S×N elements. Note that the calculated complex transfer function matrix also includes reflected waves that do not pass through the living body 20, such as direct waves and reflected waves from fixed objects.

[0202] The receiving unit 1240 may constantly calculate the complex transfer function matrix by using each of the multiple subcarrier signals that are continuously or periodically output. With this configuration, when the estimating device 1201 shares the hardware of a communication device, the complex transfer function matrix that is constantly calculated for use in the processing of the communication device can also be used by the estimating device 1201.

[0203] FIG. 16 is a diagram for explaining propagation characteristics at each timing of SIMO.

[0204] As described above, the propagation characteristics H have complex transfer functions for two types of parameters, that is, for each receiving antenna element and for each subcarrier. That is, different complex transfer functions are calculated for each of the different receiving antenna elements and for each of the different subcarriers.

[0205] 16 shows an image of the propagation characteristic h(t) expressed by a combination of complex transfer functions when the number of receiving antenna elements is three, the number of transmitting antenna elements is one, and the number of subcarriers is two. In this case, the propagation characteristic h(t) can be expressed as a combination of 3 x 1 x 2 blocks. One block represents one complex transfer function calculated for one specific receiving antenna element, one transmitting antenna element, and one specific subcarrier. In this way, the propagation characteristic H is expressed two-dimensionally because it is expressed by two types of parameters, one for each receiving antenna element and one for each subcarrier. Furthermore, this propagation characteristic h(t) is calculated for each of multiple timings.

[0206] In this embodiment, the receiving unit 1240 calculates the propagation characteristic H(t) between the transmitting antenna element and N receiving antenna elements for the sth subcarrier during the observation time t from the S IQ symbols transmitted from the receiving unit 1240, as expressed by Equation 17.

[0207]

[0208] [First complex transfer function calculation unit 1250] The first complex transfer function calculation unit 1250 calculates a first complex transfer function matrix from the complex transfer function matrix in which a first error 210 corresponding to at least one of clock fluctuation between the transmitter 1210 and the receiver 1240, and timing fluctuation in digital-to-analog conversion of the transmission signal 310 or analog-to-digital conversion of the reception signal 320 is suppressed.

[0209] The first complex transfer function calculation unit 1250 obtains eigenvectors by performing eigenvalue decomposition on the correlation matrix of the complex transfer function over a fixed observation time or over the entire observation time, and calculates a first complex transfer function matrix from the first eigenvectors. Ｒ and the correlation matrix R in the transmission direction Ｔ are calculated as in Equations 18 and 19, respectively.

[0210]

[0211]

[0212] where t ０represents the instantaneous observation time.

[0213] The first complex transfer function calculation unit 1250 performs eigenvalue decomposition on the transmission correlation matrix and the reception correlation matrix to obtain the transmission first eigenvector v １ and the first receiving eigenvector u １ When the s-th subcarrier is transmitted from the transmitting antenna, the elements of the first complex transfer function received by the n-th receiving antenna are calculated by Equation 20.

[0214]

[0215] The first complex transfer function calculation unit 1250 calculates this for different elements in all subcarrier directions, transmitting antenna element directions, and receiving antenna element directions, and calculates a first complex transfer function matrix including the calculated multiple elements.

[0216] In this embodiment, the case where there are two or more receiving antenna elements has been described, but when there is one receiving antenna element, the first error may be suppressed by dividing by the average value of adjacent subcarriers.

[0217] [Second Complex Transfer Function Calculation Unit 1260] In this embodiment, the second complex transfer function calculation unit 1260 performs a predetermined process for suppressing the second error 400, which is an error within the receiver, using the amplitude average of multiple first elements arranged in the first dimension direction 500 from the first complex transfer function calculation unit 1250. In this embodiment, the second complex transfer function calculation unit 1260 calculates a second complex transfer function matrix in which the second error 400, which is an error within the receiver, is suppressed based on the amplitude average of multiple first elements in the subcarrier direction as the first dimension direction 500. Among the elements of the second complex transfer function matrix, the elements of the second complex transfer function matrix when the s-th subcarrier is transmitted from the transmitting antenna and received by the n-th receiving antenna are expressed by Equation 21.

[0218]

[0219] The second complex transfer function calculation unit 1260 calculates this for different elements in all subcarrier directions and receiving antenna element directions, and calculates a second complex transfer function matrix including the calculated multiple elements.

[0220] In this embodiment, all of the multiple first elements are used for the amplitude average in the subcarrier direction of the first complex transfer function. However, it is also possible to use the average value of a portion (i.e., any number (two or more)) of multiple first elements aligned in the transmitting antenna direction based on the element to be processed, or multiple first elements aligned in the subcarrier direction based on the element to be processed, or multiple first elements aligned in a plane in the transmitting antenna direction and the subcarrier direction based on the element to be processed.

[0221] In this embodiment, the second complex transfer function matrix is ​​calculated using the amplitude average of a plurality of first elements, but it may also be calculated using the phase average of a plurality of first elements or the average value of both. That is, the second complex transfer function matrix may have a plurality of elements obtained by dividing each element of the first complex transfer function matrix by the phase average of a plurality of first elements or the average value of both.

[0222] In the present embodiment, the second complex transfer function matrix is ​​calculated based on the first complex transfer function matrix after the first complex transfer function matrix is ​​calculated, but the order of calculation may be reversed, i.e., the first complex transfer function matrix may be calculated based on the second complex transfer function matrix after the second complex transfer function matrix is ​​calculated.

[0223] [Third Complex Transfer Function Calculation Unit 1270] The third complex transfer function calculation unit 1270 receives the channel 630 obtained by measurement or the calculated second complex transfer function matrix, and calibrates (corrects) the third error 610, which is a phase error in the frequency direction.

[0224] The third complex transfer function calculation unit 1270 corrects the third error 610, which is a phase error in the subcarrier direction. The direct wave component is extracted from the second complex transfer function received from the second complex transfer function calculation unit 1260. Methods for determining a biological component from a complex transfer function recorded in time series include the Fourier transform disclosed in Patent Document 1 and a method using difference information disclosed in Patent Document 2.

[0225] In a method using a Fourier transform, for example, the third complex transfer function calculation unit 1270 performs a Fourier transform on the second complex transfer function matrix with respect to the observation time (slow time) to extract only specific frequency components, thereby calculating a complex transfer function corresponding to the direct wave. The third complex transfer function calculation unit 1270 extracts an arbitrary frequency component, for example, a frequency component of 0 Hz, from the frequency response complex transfer function calculated by performing a Fourier transform on the second complex transfer function matrix with respect to the observation time, and calculates a time response complex transfer function corresponding to the direct wave by performing an inverse Fourier transform on the frequency response complex transfer function corresponding to the direct wave.

[0226] Next, the third complex transfer function calculation unit 1270 calculates an ideal channel 600H between the antenna elements based on the antenna distance 620 between the transmitting antenna element and the receiving antenna element that has been input in advance. ｉｄｅａｌ The input inter-antenna distance d is a value obtained by, for example, actually measuring the distance between the transmitting antenna element and the receiving antenna element by a user. Here, H ｉｄｅａｌ is a complex matrix having elements of the number S of subcarriers, and is an ideal channel 600, H ｉｄｅａｌ is calculated by (Equation 22).

[0227]

[0228] Here, d ｎ denotes the distance between the transmitting antenna and the nth receiving antenna, and k(s) denotes the wave number of the sth subcarrier. ｉｄｅａｌ is an ideal complex transfer function between the transmitting and receiving antenna elements obtained based on the inter-antenna distance 620 between the transmitting and receiving antenna elements.

[0229] Next, the third complex transfer function calculation unit 1270 calculates the ideal channel 600, H ｉｄｅａｌ and the time response complex transfer function H corresponding to the direct wave 200. ０ The third complex transfer function calculation unit 1270 calculates a correction value for correcting a third error 610, which is a phase error in the subcarrier direction, based on the ideal channel 600, H ｉｄｅａｌ and the time response complex transfer function H corresponding to the direct wave 200. ０The correction value H ｃａｌ The correction value h of the third error 610 between the transmitting antenna element and the nth receiving antenna element in the sth subcarrier is calculated. ｃａｌ＿ｎｓ is calculated using Equation 23.

[0230]

[0231] Finally, the third complex transfer function calculation unit 1270 calculates the correction value H ｃａｌ The third complex transfer function matrix is ​​calculated based on the following equation: The third complex transfer function between the transmitting antenna element and the nth receiving antenna element in the sth subcarrier is calculated by equation 20.

[0232]

[0233] The third complex transfer function calculation unit 1270 calculates this for different elements in all subcarrier directions and receiving antenna element directions, and calculates a third complex transfer function matrix including the calculated multiple elements.

[0234] In this embodiment, the time response complex transfer function H corresponding to the direct wave 200 is ０ Although it has been stated that is calculated by Fourier transform, it may be calculated using the high-speed processing method disclosed in Patent Document 2, which does not require Fourier transform.

[0235] In this embodiment, the time response complex transfer function H corresponding to the direct wave 200 is ０ is calculated by Fourier transform, but the element h of the time response complex transfer function ０＿ｎｓ is the element h'' of the second complex transfer function matrix ｎｓ In (t), any range of real and imaginary components, for example, real and imaginary components, may be sorted in ascending order (or descending order), 10% to 90% values ​​of the sorted components may be extracted, averaged in the time direction, and the elements of the second complex transfer function matrix may be divided by the calculated average value.

[0236] Here, the third complex transfer function calculating unit 1270 may use a minimum mean square error (MMSE) filter that emphasizes the direct wave component as a reference signal using an adaptive array based on MMSE with respect to the time direction of the calculated third complex transfer function. That is, the third complex transfer function calculating unit 170 may calculate the fourth complex transfer function matrix by applying a time direction MMSE filter in which the direct wave between the transmitting antenna unit 100 and the receiving antenna unit 130 is set as a reference signal to the second complex transfer function matrix or the third complex transfer function matrix.

[0237] In this embodiment, a method for calculating a correction value from the measurement results of a complex transfer function has been described. However, if the correction value does not change over time, a value measured using a measuring instrument such as a network analyzer in a factory or the like and stored in memory may be used as the correction value.

[0238] [Biophysical correlation matrix calculation unit 1280] The biophysical correlation matrix calculation unit 1280 sequentially records, for each of the S × N combinations, the multiple complex transfer function matrices calculated by the third complex transfer function calculation unit 1270 in time series, which is the order in which the multiple received signals 320 were observed. Then, for each of the S × N combinations, the biophysical correlation matrix calculation unit 1280 calculates a biophysical component transfer function matrix expressed by an S × N-dimensional matrix by extracting components related to the biophysical organism 20 from the third complex transfer function matrix or the fourth complex transfer function matrix, which were observed during a first period sequentially recorded in time series and in which the first error 210, the second error 400, and the third error 610 have been suppressed.

[0239] Here, the biological component transfer function matrix is ​​obtained by extracting reflected waves or scattered waves (biological components) that have passed through the living body 20 and are included in the received signal 320. Methods for determining the biological components from the third complex transfer function recorded in time series include the Fourier transform disclosed in Patent Document 1 and a method using difference information disclosed in Patent Document 2.

[0240] For example, in a method using a Fourier transform, the third complex transfer function matrix is ​​Fourier transformed with respect to the observation time (slow time) to extract only specific frequency components, thereby making it possible to calculate a biological component transfer function matrix for each of a plurality of frequency components that may include the influence of biological activity, for example, those included in the range from 0.1 Hz to 3 Hz.

[0241] The time resolution Δt is expressed by Equation 25 using the subcarrier bandwidth B.

[0242]

[0243] For example, when the bandwidth is 20 MHz, the time resolution is equivalent to 0.5 μs, which is converted into a distance resolution of approximately 15 m, which is not practical.

[0244] Therefore, in this embodiment, the MUSIC method is used to improve the resolution. In order to use the MUSIC method, the biometric correlation matrix calculation unit 180 calculates a biometric correlation matrix R of the biometric component transfer function vector obtained by vectorizing the biometric component transfer function matrix. ｆ is calculated according to the following equation 26.

[0245]

[0246] [Estimation Unit 1290] The estimation unit 1290 estimates the biometric correlation matrix R calculated by the biometric correlation matrix calculation unit 1280. ｆ Distance and angle measurement is performed using the MUSIC method.

[0247] That is, the estimation unit 1290 estimates the biological correlation matrix R ｆ is decomposed into eigenvalues, and a vector U Ｓ and the eigenvector U corresponding to the noise Ｎ Here, the eigenvectors corresponding to the signal are vectors that are ordered from the first eigenvector up to the number of detection targets, and if there is one target, for example, there is only the first eigenvector. Furthermore, if there are k targets (k is a natural number equal to or greater than 2), the eigenvectors corresponding to the signal are k eigenvectors from the first eigenvector to the k-th eigenvector. Furthermore, the eigenvectors corresponding to noise refer to eigenvectors other than the eigenvector corresponding to the signal.

[0248] Using the eigenvectors obtained as above, the MUSIC spectrum P ＭＵＳＩＣ Calculate (x, y).

[0249]

[0250] Here, a(x, y) represents the steering vector, which is calculated as shown in Equation 28.

[0251]

[0252] Here, d ｎ (x, y) represents the sum of the distance between the coordinates (x, y) and the transmitting antenna element and the distance between the coordinates (x, y) and the m-th receiving antenna element, and λ(s) represents the wavelength of the s-th subcarrier. ＭＵＳＩＣ The position (x, y) at which the maximum value is obtained is estimated to be the position of the living body 20 .

[0253] In this embodiment, the estimation unit 1290 performs averaging in the biological activity frequency direction in Equation 26, but may also perform averaging in the subcarrier frequency direction, and estimate the second angle φ to the biological body as seen from the receiving antenna by applying the steering vector calculated using an arbitrary subcarrier frequency according to Equation 28 to the MUSIC method in Equation 27.

[0254]

[0255] where a(l) represents the steering vector, which is calculated as shown in Equation 30.

[0256]

[0257] The MUSIC spectrum P thus obtained ＭＵＳＩＣ The maximum value of (l) corresponds to the sum (third distance) of the distance a (first distance) between the transmitting antenna unit 1200 and the living body 20 in Figure 17 and the distance b (second distance) between the receiving antenna unit 1230 and the living body 20.

[0258] Fig. 17 is a schematic diagram showing the positional relationship between a living body, a transmitting antenna unit, and a receiving antenna unit in SIMO, and the position of the living body. In Fig. 17, the transmitting antenna unit 1200 has one transmitting antenna element, and the receiving antenna unit 1230 has multiple receiving antenna elements. In other words, Fig. 17 is an example of SIMO.

[0259] In this way, the estimation unit 1290 uses the biological correlation matrix calculated for each of the plurality of subcarriers to estimate the third distance, which is the sum of the first distance and the second distance, between the transmitting antenna unit 1200 and the living body 20. As a result, the estimation unit 1290 can estimate that the living body 20 is located on an ellipse 1310 whose foci are the transmitting antenna element and the receiving antenna element.

[0260] In this embodiment, the estimation unit 1290 estimated the position of the living body using equation 29, but the sum of the estimated distance a (first distance) between the transmitting antenna unit 1200 and the living body 20 and the distance b (second distance) between the receiving antenna unit 1230 and the living body 20 may be set as a third distance L, and the position of the living body may be estimated from the second angle φ as shown in (equation 32).

[0261]

[0262] The coordinates (x, y) of the living body 20 are calculated using the second distance b and the second angle φ by the following formula.

[0263]

[0264] Similarly, when there is one receiving antenna element as in Figure 18, the estimation unit 1290 may calculate the sum (third distance) of the distance a (first distance) between the transmitting antenna element and the living body 20 and the distance b (second distance) between the receiving antenna element and the living body 20 as in Equation 25.

[0265] Fig. 18 is a schematic diagram showing the positional relationship between a living body, a transmitting antenna unit, and a receiving antenna unit in a SISO system, and the position of the living body. In Fig. 18, the transmitting antenna unit 1200 has one transmitting antenna element, and the receiving antenna unit 1230 has one receiving antenna element. In other words, Fig. 18 is an example of a SISO system.

[0266] The MUSIC spectrum P thus obtainedＭＵＳＩＣ The maximum value of (l) corresponds to the sum (third distance) of the distance a (first distance) between the transmitting antenna unit 1200 and the living body 20 in FIG. 18 and the distance b (second distance) between the receiving antenna unit 1230 and the living body 20. In this way, the living body correlation matrix calculated for each of the multiple subcarriers is used to estimate the third distance, which is the sum of the first distance between the transmitting antenna unit 1200 and the living body 20 and the second distance between the receiving antenna unit 1230 and the living body 20. As a result, the estimation unit 1290 can estimate that the living body 20 is located on an ellipse 1410 with the transmitting antenna element and the receiving antenna element as its focus. Note that the estimation unit 1290 may estimate the position of the living body 20 from the intersection of the ellipse by estimating multiple third distances using three or more pairs of transmitting antenna units 1200 and receiving antenna units 1230.

[0267] [Operation of Estimation Device 1201] The operation of the estimation process of the estimation device 1201 configured as above will be described.

[0268] FIG. 19 is a flowchart showing the estimation process of the estimation device according to the second embodiment.

[0269] The estimation device 1201 calculates a complex transfer function for a first period (S101).

[0270] Next, the estimation device 1201 calculates a first complex transfer function matrix in which a first error 210 corresponding to at least one of clock fluctuation between the transmitter 1210 and the receiver 1240 and timing fluctuation in digital-to-analog conversion of the transmission signal 310 or analog-to-digital conversion of the reception signal 320 is suppressed (S201).

[0271] Next, the estimation device 1201 calculates a second complex transfer function matrix in which the second error 400, which is a reception internal error, is suppressed (S301).

[0272] Next, the estimation device 1201 calculates a third complex transfer function matrix in which the third error 610, which is a phase error in the subcarrier direction, is suppressed (S401).

[0273] Finally, the estimation device 1201 performs processing to estimate the direction, distance, and / or position of the living body 20 (S501).

[0274] Details of the processing of each step are omitted here because they are included in the description of the configuration of the estimation device 1201.

[0275] [Effects, etc.] In the estimation device 1201 according to this embodiment, M is 1 and N is 2 or more. The estimation device 1201 further includes an estimation unit 1290. The estimation unit 1290 estimates a third distance, which is the sum of the first distance between the transmitting antenna unit 1200 and the living body 20 and the second distance between the receiving antenna unit 1230 and the living body 20, using the third complex transfer function matrix calculated by the matrix calculation unit 1245, and estimates a second angle, which is the direction of the living body 20 as seen from the receiving antenna unit 1230, and estimates the position of the living body 20 from the third distance and the second angle.

[0276] Therefore, the position of the living body 20 relative to the estimation device 1201 can be estimated with higher accuracy.

[0277] Furthermore, in the estimation device 1201 according to this embodiment, M and N are 1. The estimation unit 1290 estimates a third distance, which is the sum of the first distance between the transmitting antenna unit 1200 and the living body 20 and the second distance between the receiving antenna unit 1230 and the living body 20, using the third complex transfer function matrix calculated by the matrix calculation unit 145.

[0278] Therefore, the distance to the living body 20 based on the estimation device 1201 can be estimated with higher accuracy.

[0279] In this way, according to this embodiment, it is possible to use an estimation device with a SIMO or SISO configuration to estimate the position (coordinates) of the living body 20, the distance between the transmitting antenna unit 1200 and the receiving antenna unit 1230 and the living body 20, and the direction (angle) in which the living body 20 is located relative to the transmitting antenna unit 1200 and the receiving antenna unit 1230.

[0280] As described above, according to the present disclosure, it is possible to realize an estimation device, an estimation method, and a program that can estimate the distance and position of a living body using a wireless signal in a short time and with high accuracy.

[0281] Here, an experiment was carried out to confirm the effect of the present embodiment, and the experiment will be described below.

[0282] [Experiment] FIG. 20 is a diagram showing the conditions of an experiment using the estimation method according to this embodiment.

[0283] Both the transmitting array antenna (Transmitter) and the receiving array antenna (Receiver) shown in FIG. 20 have a 4×4 MIMO (Multiple Input Multiple Output) configuration using a four-element patch array antenna.

[0284] In this experiment, MIMO channels were measured using these devices.

[0285] The array element spacing of the transmitting and receiving antennas was set to 0.5 wavelengths, the distance between the transmitter and receiver was 4.0 m, and the antenna height h was set to 1.0 m, which is the chest height of a human (living body) standing upright. The transmitter transmitted a 1-channel OFDM (Orthogonal Frequency Division Multiplexing) signal in the 2.4 GHz band of Wi-Fi (registered trademark), and the channel measurement time was set to 25.6 seconds. During channel measurement, there were no other people present except for the subject, who faced forward toward the wall on the antenna side, and one person stood at one of the 17 circular points to perform the measurement.

[0286] FIG. 21 is a diagram showing experimental results using the estimation method according to the first embodiment.

[0287] In Fig. 21, circles indicate estimated points, and squares indicate the actual positions where the subject stood. The MUSIC spectrum P (see Equation 13) for each position in space is also shown, indicating that the subject is estimated to be present at positions with a color close to white.

[0288] Fig. 22 is a diagram showing another experimental result using the estimation method according to embodiment 1. Fig. 22 shows the cumulative distribution function (CDF) of ranging errors. A solid line 1510 indicates the experimental result using the estimation method according to embodiment 1, and a dashed line 1520 indicates the experimental result using a conventional method.

[0289] In Figure 22, the horizontal axis represents the distance measurement error (unit: m), and the vertical axis represents the CDF of the distance measurement error. With the proposed method, the CDF value for a distance measurement error of 0.65 m is obtained as 0.75, indicating that 75% of the total errors are within 0.65 m. With the conventional method, 75% of the total errors are within 4.90 m.

[0290] Therefore, it can be seen that the estimation method according to the first embodiment can estimate the 75% value of the ranging error with 4.25 m higher accuracy than the conventional method using CSI of full MIMO. This demonstrates that the present embodiment can estimate the living body position with higher accuracy.

[0291] As described above, according to the present disclosure, even with a Wi-Fi device, it is possible to estimate the position, distance, and direction of a living body by suppressing device errors.

[0292] While the estimation device and estimation method according to one aspect of the present disclosure have been described above based on the embodiments, the present disclosure is not limited to these embodiments. As long as they do not deviate from the spirit of the present disclosure, various modifications conceivable by those skilled in the art to the present embodiment or configurations constructed by combining components of different embodiments are also included within the scope of the present disclosure.

[0293] For example, in the first and second embodiments, the estimation of the distance to the living body 20 or the position of the living body 20 based on the estimation devices 101 and 1201 has been described as an example, but the estimation target is not limited to the living body 20. The present invention is applicable to various moving objects (machines, etc.) that, when irradiated with a high-frequency signal, exert a Doppler effect on the reflected wave due to their activity.

[0294] Furthermore, the present disclosure can be realized not only as a positioning sensor having such characteristic components, but also as an estimation method in which the characteristic components included in the positioning sensor are used as steps. Furthermore, the present disclosure can also be realized as a computer program that causes a computer to execute each of the characteristic steps included in such a method. It goes without saying that such a computer program can be distributed on a non-transitory computer-readable recording medium such as a CD-ROM or via a communication network such as the Internet.

[0295] The present disclosure can be used in positioning sensors and distance estimation methods that estimate the distance to a living organism or the position of the living organism using wireless signals, and in particular in ranging sensors and direction estimation methods that are installed in measuring instruments that measure the distance to or position of a living organism, including between a living organism and a machine, home appliances that perform control according to the distance to or position of a living organism, and monitoring devices that detect the intrusion of a living organism.

[0296] 20 Living body 30 Target space 101, 1201 Estimation device 100, 1200 Transmitting antenna unit 110, 1210 Transmitting unit 120, 1220 Transmitted signal generating unit 130, 1230 Receiving antenna unit 140, 1240 Receiving unit 145, 1245 Matrix calculation unit 150, 1250 First complex transfer function calculation unit 160, 1260 Second complex transfer function calculation unit 170, 1270 Third complex transfer function calculation unit 180, 1280 Living body correlation matrix calculation unit 190, 1290 Estimation unit 200 Direct wave 210 First error 310 Transmitted signal 320 Received signal 330 Direct wave + living body-derived component 400 Second error 500 First dimension direction 600 Ideal channel 610 Third error 620 Distance between antennas 630 Channel 750-A, 750-B, 750-C Phase of each subcarrier signal transmitted from the transmitting antenna unit 760-B, 760-C Phase change of signals with different frequencies transmitted from the transmitting antenna unit 800, 810 Phase change with respect to frequency of complex transfer function matrix 910 Solid line 920 Dashed line 1010, 1310, 1410 Ellipse in which a living body may exist, determined by the third distance 1510 Solid line 1520 Dashed line

Claims

1. a transmission signal generator that generates a multicarrier signal in which S (S is a natural number equal to or greater than 2) subcarrier signals are modulated; a transmitting antenna unit having M (M is a natural number equal to or greater than 1) transmitting antenna elements; a transmitting unit that processes the multicarrier signal and outputs the processed multicarrier signal to the transmitting antenna unit, thereby transmitting the multicarrier signal to the transmitting antenna unit; a receiving antenna unit having N (N is a natural number equal to or greater than 1) receiving antenna elements; a receiving unit that observes, for a first period corresponding to a cycle derived from activity of the living body, received signals received by each of the N receiving antenna elements, the received signals including reflected signals resulting from reflection or scattering of the multicarrier signals transmitted from each of the M transmitting antenna elements by a living body, and calculates, for each of N×M combinations of each of the M transmitting antenna elements and each of the N receiving antenna elements, a plurality of complex transfer functions representing propagation characteristics between the transmitting antenna element and the receiving antenna element in the combination, for each of S subcarriers to which the S subcarrier signals respectively correspond; (i) calculating a second complex transfer function matrix by performing a predetermined process on each of N×M×S elements in a first complex transfer function matrix including the complex transfer functions obtained for each of the S subcarriers and each of the N×M combinations as elements of an N×M×S three-dimensional array; and (ii) a matrix calculation unit that calculates an offset value with respect to a reference phase calculated from a positional relationship between the transmitting antenna unit and the receiving antenna unit, and calculates a third complex transfer function matrix by correcting the second complex transfer function matrix based on the offset value, the predetermined processing is processing of calculating an amplitude average of a plurality of first elements including an element to be processed, and dividing the element to be processed by the amplitude average; The plurality of first elements are included in the S×M elements obtained for one receiving antenna element corresponding to the element to be processed. Estimation device.

2. The plurality of first elements are M elements obtained for one receiving antenna element corresponding to the element to be processed and one subcarrier corresponding to the element to be processed. The estimation device according to claim 1 .

3. The plurality of first elements are S elements obtained for one receiving antenna element corresponding to the element to be processed and one transmitting antenna element corresponding to the element to be processed. The estimation device according to claim 1 .

4. The plurality of first elements are the S×M elements. The estimation device according to claim 1 .

5. The matrix calculation unit converting the second complex transfer function matrix into a frequency response matrix or a frequency response vector, and extracting a frequency response matrix or a frequency response vector corresponding to a direct wave between the transmitting antenna unit and the receiving antenna unit; calculating an ideal complex transfer function corresponding to the direct wave, and calculating, as the offset value, correction values ​​for correcting phase errors in S second elements of the second complex transfer function matrix for each of the N×M combinations, based on the ideal complex transfer function and the frequency response matrix or the frequency response vector; Calculating the third complex transfer function matrix in which the phase error has been corrected based on the correction value The estimation device according to claim 4 .

6. The matrix calculation unit calculating an average value by averaging all elements or a plurality of third elements of the second complex transfer function matrix in a real part direction and an imaginary part direction, calculating an ideal complex transfer function corresponding to a direct wave between the transmitting antenna unit and the receiving antenna unit, and calculating, as the offset value, correction values ​​for correcting phase errors in S second elements of the second complex transfer function matrix for each of the N×M combinations based on the ideal complex transfer function and the average value; Calculating the third complex transfer function matrix in which the phase error has been corrected based on the correction value The estimation device according to claim 4 .

7. The matrix calculation unit further A fourth complex transfer function matrix is ​​calculated by applying a time-direction MMSE (Minimum Mean Square Error) filter, in which a direct wave between the transmitting antenna unit and the receiving antenna unit is set as a reference signal, to the second complex transfer function matrix or the third complex transfer function matrix. The estimation device according to any one of claims 4 to 6.

8. The first complex transfer function matrix is ​​a direct wave component extracted using one or more elements of N×M×S complex transfer functions, which are a set of the complex transfer functions obtained for each of the S subcarriers and each of the N×M combinations, and has N×M×S corrected elements obtained by dividing all elements of the N×M×S complex transfer functions by the direct wave component that does not pass through the living body. The estimation device according to claim 1 .

9. M and N are 2 or more, The estimation device further and an estimation unit that estimates a position of the living body from a first angle, which is a direction of the living body as seen from the M transmitting antenna elements, and a second angle, which is a direction of the living body as seen from the N receiving antenna elements, using the third complex transfer function matrix calculated by the matrix calculation unit. The estimation device according to any one of claims 4 to 6.

10. At least one of M and N is 2 or more, The estimation device further and an estimation unit that estimates a third distance, which is the sum of a first distance between the transmitting antenna unit and the living body and a second distance between the receiving antenna unit and the living body, using the third complex transfer function matrix calculated by the matrix calculation unit, estimates a first angle or a second angle, which is a direction of the living body as seen from two or more antenna elements of the transmitting antenna unit or the receiving antenna unit, and estimates a position of the living body from the third distance and the first angle or the second angle. The estimation device according to any one of claims 4 to 6.

11. The M and the N are 1; and an estimation unit that estimates a third distance, which is the sum of a first distance between the transmitting antenna unit and the living body and a second distance between the receiving antenna unit and the living body, using the third complex transfer function matrix calculated by the pre-matrix calculation unit. The estimation device according to any one of claims 4 to 6.

12. The estimation unit estimates the first distance, the second distance, the first angle, and the second angle using any one of a MUSIC (Multiple Signal Classification) method, a beamformer method, and a Capon method. The estimation device according to claim 10.

13. An estimation method using an estimation device including a transmitting antenna unit having M (M is a natural number equal to or greater than 1) transmitting antenna elements and a receiving antenna unit having N (N is a natural number equal to or greater than 1) receiving antenna elements, generating a multicarrier signal in which S (S is a natural number equal to or greater than 2) subcarrier signals are modulated; The multicarrier signal is processed and output to the transmitting antenna unit, thereby transmitting the multicarrier signal to the transmitting antenna unit; Observing received signals received by each of the N receiving antenna elements, the received signals including reflected signals of the multicarrier signals transmitted from each of the M transmitting antenna elements reflected or scattered by a living body, for a first period corresponding to a cycle resulting from activity of the living body; using the plurality of received signals observed during the first time period, for each of N×M combinations of the M transmitting antenna elements and the N receiving antenna elements, calculating a plurality of complex transfer functions representing propagation characteristics between the transmitting antenna elements and the receiving antenna elements in the combination, for each of S subcarriers to which the S subcarrier signals respectively correspond; calculating a second complex transfer function matrix by performing a predetermined process on each of N×M×S elements in a first complex transfer function matrix including the complex transfer functions obtained for each of the S subcarriers and each of the N×M combinations as elements of an N×M×S three-dimensional array; calculating an offset value with respect to a reference phase calculated from a positional relationship between the transmitting antenna unit and the receiving antenna unit, and calculating a third complex transfer function matrix by correcting the second complex transfer function matrix based on the offset value; the predetermined processing is processing of calculating an amplitude average of a plurality of first elements including an element to be processed, and dividing the element to be processed by the amplitude average; The plurality of first elements are included in the S×M elements obtained for one receiving antenna element corresponding to the element to be processed. Estimation method.

14. A program for causing a computer to execute the estimation method according to claim 13.