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

[Technical Field]

[0001] This disclosure relates to an estimation device and estimation method for estimating the distance or position to a living organism using wireless signals. [Background technology]

[0002] Methods using wireless signals are being considered to determine the location of a person (see, for example, Patent Documents 1 to 4). Patent Documents 1, 2, and 3 disclose a technique for estimating the location and state of a person to be detected by analyzing components including Doppler shift using difference calculations. Patent Documents 4 and 5 disclose a Doppler sensor using OFDM (Orthogonal Frequency Division Multiplexing) signals. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2015-117972 [Patent Document 2] Japanese Patent Publication No. 2017-129558 [Patent Document 3] Japanese Patent Publication No. 2018-008021 [Patent Document 4] Japanese Patent Publication No. 2012-088279 [Patent Document 5] Japanese Patent Publication No. 2012-137340 [Non-patent literature]

[0004] [Non-Patent Document 1] 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

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the conventional method, it is difficult to estimate the distance from the estimation device to the living body, the direction to the living body, etc. with higher accuracy.

Means for Solving the Problems

[0006] To achieve the above object, an estimation device according to one embodiment of the present disclosure includes a transmission signal generation unit that generates a multi-carrier signal modulated by S sub-carrier signals (S is a natural number of 2 or more), a transmission antenna unit having M transmission antenna elements (M is a natural number of 1 or more), a transmission unit that processes the multi-carrier signal and outputs it to the transmission antenna unit to transmit the multi-carrier signal to the transmission antenna unit, a reception antenna unit having N reception antenna elements (N is a natural number of 1 or more), and reception signals received by each of the N reception antenna elements, including reflection signals obtained by reflecting or scattering the multi-carrier signal transmitted from each of the M transmission antenna elements by a living body. For a first period corresponding to a period derived from the activity of the living body, the reception unit observes the reception signals, and using the plurality of reception signals observed during the first period, for each of N×M combinations, which are combinations of each of the M transmission antenna elements and each of the N reception antenna elements, a complex transfer function representing the propagation characteristics between the transmission antenna element and the reception antenna element in the combination is calculated for each of the S sub-carriers corresponding to each of the S sub-carrier signals.(i) For each of the S sub-carriers and for each of the N×M combinations, 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 that includes the complex transfer functions obtained as elements of a three-dimensional array of N×M×S. (ii) calculate an offset value relative to the reference phase calculated from the positional relationship between the transmitting antenna section and the receiving antenna section, and calculate a third complex transfer function matrix obtained by correcting the second complex transfer function matrix based on the offset value. It includes a matrix calculation unit, and the predetermined process is a process of calculating an amplitude average of a plurality of first elements including the element to be processed and dividing the element to be processed by the amplitude average. The plurality of first elements are included in S×M elements obtained for one receiving antenna element corresponding to the element to be processed.

[0007] Also, an estimation method according to one embodiment of the present disclosure is an estimation method by an estimation device including a transmission antenna unit having M (M is a natural number of 1 or more) transmission antenna elements and a reception antenna unit having N (N is a natural number of 1 or more) reception antenna elements. A multi-carrier signal modulated by S (S is a natural number of 2 or more) sub-carrier signals is generated, the multi-carrier signal is processed and output to the transmission antenna unit, so that the multi-carrier signal is transmitted to the transmission antenna unit, and a reception signal received by each of the N reception antenna elements, the reception signal including a reflection signal obtained by reflecting or scattering the multi-carrier signal transmitted from each of the M transmission antenna elements by a living body, is observed for a first period corresponding to a period derived from the activity of the living body, and using the plurality of reception signals observed in the first period, for each of N×M combinations which are combinations of each of the M transmission antenna elements and each of the N reception antenna elements, a plurality of complex transfer functions representing propagation characteristics between the transmission antenna element and the reception antenna element in the combination are calculated for each of the S sub-carriers corresponding to each of the S sub-carrier signals, 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 that includes the complex transfer functions obtained as elements of a three-dimensional array of N×M×S for each of the S sub-carriers and for each of the N×M combinations. An offset value relative to the reference phase calculated from the positional relationship between the transmitting antenna section and the receiving antenna section is calculated, and a third complex transfer function matrix is ​​calculated by correcting the second complex transfer function matrix based on the offset value.The predetermined process involves calculating the amplitude average of a plurality of first elements, including the element to be processed, and dividing the element to be processed by the amplitude average, wherein the plurality of first elements are included in S × M elements obtained for one receiving antenna element corresponding to the element to be processed.

[0008] These general or specific embodiments may be implemented as a system, integrated circuit, computer program, or recording medium such as a computer-readable CD-ROM, or as any combination of apparatus, system, method, integrated circuit, computer program, and recording medium. [Effects of the Invention]

[0009] According to this disclosure, it is possible to estimate the position of living organisms with higher accuracy. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a block diagram showing an example of the configuration of the estimation device in Embodiment 1. [Figure 2] Figure 2 is a diagram illustrating the relationship between the transmitted signal, channel, and received signal. [Figure 3] Figure 3 is a diagram illustrating the propagation characteristics at each timing stage of MIMO. [Figure 4] Figure 4 is a schematic diagram showing the first error. [Figure 5] Figure 5 shows an example of the first error. [Figure 6] Figure 6 is a schematic diagram showing the second error. [Figure 7] Figure 7 shows an example of the second error. [Figure 8] Figure 8 is a schematic diagram illustrating the third error. [Figure 9] Figure 9 is a schematic diagram showing the relationship between the third error and the channel. [Figure 10] Figure 10 is a schematic diagram showing the relationship between frequency and the slope of the phase difference. [Figure 11]Figure 11 is a schematic diagram showing the phase of the time-domain biological component transfer function matrix. [Figure 12] Figure 12 is a schematic diagram showing the positional relationship between the living organism, the transmitting antenna, and the receiving antenna in MIMO, as well as the position of the living organism. [Figure 13] Figure 13 is a schematic diagram showing the positional relationship between the living organism, the multiple transmitting antenna section, and the receiving antenna section, as well as the position of the living organism, in MISO. [Figure 14] Figure 14 is a flowchart showing the estimation process of the estimation device in Embodiment 1. [Figure 15] Figure 15 is a block diagram showing an example of the configuration of the estimation device in Embodiment 2. [Figure 16] Figure 16 is a diagram illustrating the propagation characteristics at each timing of SIMO. [Figure 17] Figure 17 is a schematic diagram showing the positional relationship between the living organism, the transmitting antenna unit, and the receiving antenna unit, as well as the position of the living organism, in SIMO. [Figure 18] Figure 18 is a schematic diagram showing the positional relationship between the living organism, the transmitting antenna unit, and the receiving antenna unit, as well as the position of the living organism, in SISO. [Figure 19] Figure 19 is a flowchart showing the estimation process of the estimation device in Embodiment 2. [Figure 20] Figure 20 shows the experimental conditions using the estimation method according to Embodiment 1. [Figure 21] Figure 21 shows an example of the estimation results using the estimation method according to Embodiment 1. [Figure 22] Figure 22 shows a statistical example of the estimation error using the estimation method according to Embodiment 1. [Modes for carrying out the invention]

[0011] (Knowledge that forms the basis of this disclosure) Methods using wireless signals are being considered as a way to determine a person's location.

[0012] For example, Patent Documents 1 and 2 disclose a method for transmitting a wireless signal to a predetermined area, receiving the reflected wireless signal at the detection target with multiple antennas, and estimating the complex transfer function between the transmitting and receiving antennas. The complex transfer function is a function composed of complex numbers that represent the relationship between input and output, and represents the propagation characteristics between the transmitting and receiving antennas. The number of elements in 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 for estimating the posture of a living organism using RCS (Radar Cross Section) obtained from the received power, using a configuration similar to that of Patent Document 2. RCS is an index that represents the area of ​​an object that reflects the transmitted wave, and the RCS of a living organism changes in various ways depending on the posture of the organism.

[0013] Patent Document 1 further discloses a processing device that can determine the location or state of a person to be detected by analyzing a component containing a Doppler shift using a Fourier transform. More specifically, the processing device records the time evolution of the 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 reflected waves due to biological activities such as breathing and heartbeat. Therefore, the component containing a Doppler shift obtained from the reflected wave includes the influence of the living organism. On the other hand, the component without a Doppler shift obtained from the reflected wave is not influenced by the living organism. In other words, the component without a Doppler shift corresponds to a reflected wave from a fixed object or a direct wave between transmitting and receiving antennas. That is, by using the component included in a predetermined frequency range in the Fourier-transformed waveform, the location or state of the person to be detected can be obtained.

[0014] Patent Document 2 discloses a method for extracting components that include slight Doppler shifts, which are influenced by biological factors, by recording the time evolution of elements of a complex transfer function and analyzing the difference information. In other words, this method allows the location and state of the person to be detected to be determined 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 moving object. Furthermore, Patent Document 4 discloses a high-speed processing method for OFDM Doppler radar that does not require a 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 an OFDM signal. Patent Document 5 discloses that the received noise component can be reduced by averaging the complex transfer function for each subcarrier.

[0017] However, since the methods described in Patent Documents 1, 2, and 3 transmit unmodulated waves, it is difficult to use commercially available devices, and dedicated hardware is required. In other words, currently available communication devices cannot be used, and users need to install dedicated hardware in addition to their existing communication equipment.

[0018] Furthermore, the methods described in Patent Documents 4 and 5 also require a steep transmission pulse to achieve sufficient accuracy, which necessitates a wide frequency bandwidth. Consequently, the hardware cost is higher compared to consumer-grade communication devices.

[0019] The technology described in Non-Patent Document 1 allows for the estimation of the Time of Flight (ToF) between a transmitting antenna and a receiving antenna, or the distance that can be calculated from ToF, by transmitting and receiving signals of multiple frequencies using a measuring instrument such as a network analyzer. This utilizes the property that, similar to ranging sensors using FMCW (Frequency Modulated Continuous Wave) radar, when two signals of different frequencies are transmitted in 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 in Non-Patent Document 1 further improves the 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. Furthermore, it can only estimate the distance between antennas, making it difficult to estimate the distance between a device and, for example, a living organism without special equipment.

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

[0022] In other words, the estimation device according to the first aspect of the present disclosure includes: a transmission signal generation unit that generates a multicarrier signal modulated with S subcarrier signals (S is a natural number of 2 or more); a transmission antenna unit having M transmission antenna elements (M is a natural number of 1 or more); a transmission unit that processes the multicarrier signal and outputs it to the transmission antenna unit so that the multicarrier signal is transmitted to the transmission antenna unit; a receiving antenna unit having N receiving antenna elements (N is a natural number of 1 or more); and a receiving signal received by each of the N receiving antenna elements, which includes a reflected signal in which the multicarrier signal transmitted from each of the M transmitting antenna elements is reflected or scattered by the living organism, observed for a first period corresponding to a period derived from the activity of the living organism; and using a plurality of the received signals observed in the first period, the device uses each of the M transmitting antenna elements and the N receiving antenna elements to determine the value of the signal. The system includes a receiving unit that calculates multiple complex transfer functions representing the propagation characteristics between the transmitting antenna element and the receiving antenna element for each of the N×M combinations, each of which is a combination of each of the S subcarrier signals, for each of the S subcarrier signals; and a matrix calculation unit that 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 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 is to calculate the amplitude average of a plurality of first elements including the element to be processed, and divide 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.

[0023] According to this method, a predetermined process is performed for each of the N×M×S elements in the first complex transfer function matrix, which involves calculating the amplitude average of multiple first elements that are included in the S×M elements obtained for a single receiving antenna element corresponding to the element to be processed, and dividing the element to be processed by the amplitude average. As a result, the first error introduced to the received signal by each receiving antenna element can be reduced. Therefore, the position of a living organism can be estimated with high accuracy.

[0024] Furthermore, this configuration makes it possible to realize a bio-radar that measures the distance and position to living organisms by using multi-carrier signals such as OFDM for the transmission signal and reusing existing communication equipment. For example, receivers for multi-carrier signals such as OFDM are already widely used in mobile phones, television broadcast receivers, and wireless LAN equipment, making it possible to realize a bio-radar that measures the distance and position to living organisms at a lower cost than when using unmodulated signals.

[0025] An estimation device according to a second aspect of the present disclosure is an estimation device according to a 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 being processed and one subcarrier corresponding to the element being processed.

[0027] An estimation device according to a third aspect of the present disclosure is an estimation device according to a 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 being processed and one transmitting antenna element corresponding to the element being processed.

[0029] An estimation device according to a fourth aspect of this disclosure is an estimation device according to a 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 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 obtained by correcting the second complex transfer function matrix based on the offset value.

[0032] This reduces the third error relative to the reference phase, allowing for more accurate estimation of the position of living organisms.

[0033] An estimation device according to a sixth aspect of the present disclosure is an estimation device according to a fifth aspect, wherein the matrix calculation unit converts the second complex transfer function matrix into a frequency response matrix or frequency response vector, extracts a frequency response matrix or frequency response vector corresponding to the direct wave between the transmitting antenna unit and the receiving antenna unit, calculates an ideal complex transfer function corresponding to the direct wave, calculates a correction value as the offset value for correcting the phase error 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 frequency response vector, and calculates the third complex transfer function matrix with the phase error corrected based on the correction value.

[0034] Therefore, phase errors in the subcarrier direction can be eliminated, allowing for more accurate measurement of the distance from the estimation device to the living organism.

[0035] An estimation device according to a seventh aspect of the present disclosure is an estimation device according to a fifth aspect, wherein the matrix calculation unit calculates an average value obtained by averaging all or a plurality of third elements of the second complex transfer function matrix in the real part direction and the imaginary part direction, respectively, calculates an ideal complex transfer function corresponding to the direct wave between the transmitting antenna unit and the receiving antenna unit, calculates a correction value as the offset value for correcting the phase error 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, and calculates the third complex transfer function matrix with the phase error corrected based on the correction value.

[0036] Therefore, phase errors in the subcarrier direction can be eliminated, allowing for more accurate measurement of the distance from the estimation device to the living organism.

[0037] An estimation device according to the eighth aspect of the present disclosure is an 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 the 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, allowing for more accurate measurement of the distance from the estimation device to the living organism.

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

[0040] This makes it possible to reduce the first error, which is a component corresponding to at least one of (1) clock fluctuations between the transmitter, consisting of a transmitting signal generation unit and a transmitting unit that transmit signals from the transmitting antenna unit, and the receiver, consisting of a receiving unit that receives signals from the receiving antenna unit, and (2) timing fluctuations in the digital-to-analog conversion of the transmitted signal or the analog-to-digital conversion of the received signal. Therefore, it is possible to estimate the position of living organisms and other objects with higher accuracy.

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

[0042] Therefore, it is possible to estimate the position of a living organism with higher accuracy, based on the estimation device.

[0043] An estimation device according to the eleventh aspect of the present disclosure is an estimation device according to any one aspect of the fifth to eighth aspects, wherein at least one of M and N is 2 or more, and the estimation device further 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 organism and a second distance between the receiving antenna unit and the living organism, using the third complex transfer function matrix calculated by the matrix calculation unit, estimates a first angle or a second angle which is the direction of the living organism 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 organism from the third distance and the first angle or the second angle.

[0044] Therefore, it is possible to estimate the position of a living organism with higher accuracy, based on the estimation device.

[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 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 organism and a second distance between the receiving antenna unit and the living organism, using the third complex transfer function matrix calculated by the pre-matrix calculation unit.

[0046] Therefore, it is possible to estimate the distance to a living organism with higher accuracy, using the estimation device as a reference.

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

[0048] Therefore, it is possible to estimate the distance to a living organism with higher accuracy, using the estimation device as a reference.

[0049] An estimation method relating to a 14th aspect of the present disclosure is an estimation method using an estimation device comprising: a transmitting antenna unit having M transmitting antenna elements (where M is a natural number of 1 or more); and a receiving antenna unit having N receiving antenna elements (where N is a natural number of 1 or more), wherein a multicarrier signal is generated by modulating S subcarrier signals (where S is a natural number of 2 or more), the multicarrier signal is processed and output to the transmitting antenna unit so that the multicarrier signal is transmitted to the transmitting antenna unit, the received signals received by each of the N receiving antenna elements, including reflected signals in which the multicarrier signal transmitted from each of the M transmitting antenna elements is reflected or scattered by the living organism, are observed for a first period corresponding to a period derived from the activity of the living organism, and the plurality of received signals observed in the first period are used to determine each of the M transmitting antenna elements For each of the N×M combinations, which are combinations of the transmitting antenna element and each of the N receiving antenna elements, a complex transfer function representing the propagation characteristics between the transmitting antenna element and the receiving antenna element in that combination is calculated for each of the S subcarriers corresponding to each of the S subcarrier signals. 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 that includes the complex transfer functions obtained for each of the S subcarriers and for each of the N×M combinations as elements in an N×M×S three-dimensional array. The predetermined process involves calculating the amplitude average of a plurality of first elements including the 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.

[0050] According to this method, a predetermined process is performed for each of the N×M×S elements in the first complex transfer function matrix, which involves calculating the amplitude average of multiple first elements that are included in the S×M elements obtained for a single receiving antenna element corresponding to the element to be processed, and dividing the element to be processed by the amplitude average. As a result, the first error introduced to the received signal by each receiving antenna element can be reduced. Therefore, the position of a living organism can be estimated with high accuracy.

[0051] Furthermore, this configuration makes it possible to realize a bio-radar that measures the distance and position to living organisms by using multi-carrier signals such as OFDM for the transmission signal and reusing existing communication equipment. For example, receivers for multi-carrier signals such as OFDM are already widely used in mobile phones, television broadcast receivers, and wireless LAN equipment, making it possible to realize a bio-radar that measures the distance and position to living organisms at a lower cost than when using unmodulated signals.

[0052] A program relating to the 15th aspect of this disclosure is a program for causing a computer to execute the estimation method relating to the 14th aspect.

[0053] This configuration makes it possible to realize a bio-radar that measures the distance and position to living organisms by using multi-carrier signals such as OFDM for the transmission signal and repurposing existing communication equipment. For example, receivers for multi-carrier signals such as OFDM are already widely used in mobile phones, television broadcast receivers, and wireless LAN equipment, making it possible to realize a bio-radar that measures the distance and position to living organisms at a lower cost than when using unmodulated signals.

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

[0055] The embodiments of this disclosure will be described in detail below with reference to the drawings. The embodiments described below are all preferred examples of the disclosure. The numerical values, shapes, materials, components, arrangement and connection configurations of components, steps, and the order of steps shown in the following embodiments are examples only and are not intended to limit the disclosure. Furthermore, components in the following embodiments that are not described in the independent claims representing the highest-level concepts of this disclosure will be described as any component constituting a more preferred configuration. In this specification and in the drawings, components having substantially the same functional configuration are denoted by the same reference numerals to avoid redundant explanation.

[0056] (Embodiment 1) Embodiment 1 describes a method for detecting living organisms in the case of a MIMO (Multiple Input Multiple Output) system, where both the transmitting antenna and the receiving antenna have multiple antenna elements. This method is also applicable to a MISO (Multiple Input Single Output) system, where there are multiple transmitting antenna elements and a single receiving antenna element.

[0057] [Configuration of Estimation Device 101] Figure 1 is a block diagram showing an example of the configuration of the estimation device in Embodiment 1.

[0058] The estimation device 101 shown in Figure 1 comprises a transmitting antenna unit 100, a transmitting unit 110, a transmitting signal generation unit 120, a receiving antenna unit 130, a receiving unit 140, a matrix calculation unit 145, a bio-correlation matrix calculation unit 180, and an estimation unit 190. The matrix calculation unit 145 has 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 the living organism 20. The estimation device 101 may also estimate the position of the living organism 20 in the target space, estimate the posture of the living organism 20, determine whether or not the living organism 20 exists in the target space, identify the living organism 20 based on information (complex transfer function matrix) registered in advance for each individual living organism 20, or estimate the movement of the living organism 20.

[0059] [Transmitting antenna section 100] The transmitting antenna unit 100 has M transmitting antenna elements. Here, M is a natural number of 1 or more. In this embodiment, since MIMO or MISO will be described as described above, M is a natural number of 2 or more. As described above, the transmitting antenna elements transmit the multi-carrier signal (transmitted wave) generated by the transmitting unit 110, which will be described later.

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

[0061] Furthermore, the signal generated by the transmission signal generation unit 120 may be shared with the signal used for communication. In other words, the transmission signal used to sense the biological organism 20 may be used exclusively for sensing the biological organism 20, or it may be used for both sensing the biological organism 20 and information communication.

[0062] [Transmitter 110] The transmitting unit 110 processes the signal generated by the transmitting signal generation unit 120 to generate a transmission wave. This processing includes, for example, upconversion (converting the signal from the IF (Intermediate Frequency) band to the RF (Radio Frequency) band) and amplification (amplifying the signal to an appropriate transmission level). The transmitting unit 110 outputs the processed multi-carrier signal to the transmitting antenna unit 100, causing the antenna unit 100 to transmit the signal. As a result, the multi-carrier signal is transmitted from the M transmitting antenna elements of the transmitting antenna unit 100.

[0063] [Receiving antenna section 130] The receiving antenna unit 130 has N receiving antenna elements, where N is a natural number greater than or equal to 1. In this embodiment, N is a natural number greater than or equal to 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 M transmitting antenna elements and reflected by the living organism 20.

[0064] [Receiver 140] The receiving unit 140 observes the received signal 320, which is received by N receiving antenna elements and includes reflected signals that are reflected or scattered by the living organism 20 from the multicarrier signals transmitted from M transmitting antenna elements, for a first period corresponding to a period derived from the activity of the living organism 20. The period derived from the activity of the living organism is a period derived from the living organism (living fluctuation period) that is half a period or longer of any of the periods of respiration, heartbeat, or body movement of the living organism 20.

[0065] The receiving unit 140 converts the high-frequency signals received by the N receiving antenna elements into low-frequency signals that can be processed. The receiving unit 140 also has N amplifiers to amplify the signals received by the N receiving antenna elements, one for each of the N receiving antenna elements. In other words, each of the N amplifiers corresponds to one of the N receiving antenna elements. The receiving unit 140 then demodulates the OFDM signal into S subcarrier signals (IQ symbols).

[0066] The receiving unit 140 further calculates multiple complex transfer functions representing the propagation characteristics between the transmitting antenna element and the receiving antenna element for each subcarrier, based on the multiple IQ symbols observed during the first period.

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

[0068] The receiving unit 140 uses the multiple received signals 320 observed during the first period to calculate a complex transfer function representing the propagation characteristics between the transmitting antenna elements and the receiving antenna elements for each of the N × M combinations, which are combinations of each of the M transmitting antenna elements and each of the N receiving antenna elements. This complex transfer function is calculated for each of the multiple subcarriers that each of the multiple subcarrier signals corresponds to. Note that the N × M combinations are all possible combinations when the 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 an N×M×S complex transfer function for each of the S subcarrier signals, representing the propagation characteristics between each transmitting antenna element and each receiving antenna element. The receiving unit 140 may then generate a complex transfer function matrix having N×M×S elements. The calculated complex transfer function matrix includes reflected waves that do not pass through the living organism 20, such as direct waves and reflected waves originating from fixed objects.

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

[0071] Figure 2 is a diagram illustrating the relationship between the transmitted signal, channel, and received signal.

[0072] The transmitted signal X sent from the transmitting antenna unit 100 propagates through the target space 30 and is received by the receiving antenna unit 130, where it is acquired as the received signal Y. The received signal Y received by the receiving antenna unit 130 is a signal that has changed as the transmitted signal X propagates through the target space 30. Therefore, the received signal Y can be considered to be equal to the signal obtained by multiplying the propagation characteristics H of the target space 30 by the transmitted signal X. The propagation characteristics H is represented by the N×M×S complex transfer function described above.

[0073] Figure 3 is a diagram illustrating the propagation characteristics at each timing stage of MIMO.

[0074] As described above, the propagation characteristic H has a complex transfer function for each combination of three types of parameters: each receiving antenna element, each transmitting antenna element, and each subcarrier. In other words, a different complex transfer function is calculated for each of several different receiving antenna elements, a different complex transfer function is calculated for each of several different transmitting antenna elements, and a different complex transfer function is calculated for each of several different subcarriers.

[0075] Figure 3 shows an image of the propagation characteristics H represented by combinations of complex transfer functions when the number of receiving antenna elements is 3, the number of transmitting antenna elements is 4, and the number of subcarriers is 2. In this case, the propagation characteristics H can be represented as a combination of 3 × 4 × 2 blocks. Each block represents one complex transfer function calculated for a specific receiving antenna element, a specific transmitting antenna element, and a specific subcarrier. Thus, since the propagation characteristics H are represented as a combination of three types of parameters—receiving antenna elements, transmitting antenna elements, and subcarriers—they can be represented three-dimensionally. Furthermore, this three-dimensionally represented propagation characteristics H are calculated for each of multiple timings. In other words, the propagation characteristics H are represented by a complex transfer function matrix that includes the complex transfer function obtained for each of the S subcarriers and for each of the N × M combinations as each element of a three-dimensional array of N × M × S.

[0076] In addition, the subcarrier and transmitting antenna element may be fixed, and the multiple complex transfer functions of different receiving antenna elements may be expressed as multiple complex transfer functions different in the direction of the receiving antenna element. Similarly, the subcarrier and receiving antenna element may be fixed, and the multiple complex transfer functions of different transmitting antenna elements may be expressed as multiple complex transfer functions different in the direction of the transmitting antenna element. Similarly, the receiving antenna element and transmitting antenna element may be fixed, and the multiple complex transfer functions of different subcarriers may be expressed as multiple complex transfer functions different in the direction of the subcarrier. Thus, in the propagation characteristics H expressed in three dimensions, the directions of each dimension may be expressed using names related to three types of parameters as the direction of the receiving antenna element, the direction of the transmitting antenna element, and the direction of the subcarrier.

[0077] For example, if we assign the rows of the matrix representing the propagation characteristics H to the receiving antenna elements of the third order and the columns to the transmitting antenna elements, then different propagation characteristics H will be calculated for each subcarrier and for each timing of receiving the signal. In other words, in this embodiment, the receiving unit 140 determines the propagation characteristics H(t,s) between the M transmitting antenna elements and the N receiving antenna elements for the sth subcarrier during the observation time t, based on the S subcarrier signals transmitted from the receiving unit 140, and expresses this in a complex transfer function matrix as shown in Equation 1.

[0078]

number

[0079] [First complex transfer function calculation unit 150] Figures 4 and 5 schematically illustrate an example of the first error.

[0080] The first complex transfer function calculation unit 150 calculates a first complex transfer function matrix from which a first error 210 corresponding to at least one of the clock fluctuations between the transmitter unit 110 and the receiver unit 140, or the timing fluctuations of the digital-to-analog conversion of the transmitted signal 310 or the analog-to-digital conversion of the received signal 320 is suppressed. The received signal 320 includes a time-random first error 210 for the direct wave + bio-derived component 330, which includes the direct wave 200 and the bio-derived 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 extracted using one or more elements from the N×M×S complex transfer functions, which are the set of complex transfer functions obtained for each of the S subcarriers and for each of the N×M combinations, and which do not pass through the living organism 20. As a result, 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 obtains eigenvectors for the complex transfer function by performing eigenvalue decomposition on the correlation matrix of the complex transfer function over a certain observation time or the entire observation time, and calculates the first complex transfer function from the first eigenvectors. The correlation matrix R in the transmission direction is obtained from the propagation characteristics H(t,s) of the s-th subcarrier. R (s) and the correlation matrix R of the transmission direction T (s) is calculated as shown in Equations 2 and 3, respectively.

[0083]

number

[0084]

number

[0085] Here, t0 represents the instantaneous observation time.

[0086] The first complex transfer function calculation unit 150 performs eigenvalue decomposition on the transmit correlation matrix and the receive correlation matrix to calculate the first transmit eigenvector v1(s) and the first receive eigenvector u1(s). The elements of the first complex transfer function, when the s-th subcarrier is transmitted from the m-th transmitting antenna and received by the n-th receiving antenna, are calculated using Equation 4.

[0087]

number

[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 that includes the multiple elements calculated.

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

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

[0091] As mentioned above, the direct wave component may also be the channel component of the direct wave, calculated by multiplying the complex transfer function by the eigenvector that maximizes the eigenvalue among the pairs of eigenvalues ​​and eigenvectors obtained by eigenvalue decomposition of N×M×S complex transfer functions. Furthermore, the direct wave component may be any one of the N×M×S complex transfer functions, or it may be the average of the N×M×S complex transfer functions. In addition, the direct wave component may also be the channel component of the direct wave, calculated by multiplying the complex transfer function by the left singular vector and right singular vector obtained by singular value decomposition of N×M×S complex transfer functions.

[0092] [Second complex transfer function calculation unit 160] Figures 6 and 7 schematically illustrate 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 in-receiver error, using the amplitude average of a plurality of 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 has been suppressed based on the amplitude average of a plurality of first elements in the direction of the transmitting antenna element as the first dimension direction 500. The elements of the second complex transfer function matrix in which the s-th subcarrier is transmitted from the m-th transmitting antenna and received by the n-th receiving antenna are represented by Equation 5.

[0094]

number

[0095] As shown in Figure 7, the signal after amplification by the receiver 140 includes a second error due to amplification as an internal receiver error. This second error appears at the same timing and with similar amplitude regardless of the transmitting antenna element or subcarrier. Therefore, by calculating the amplitude average of multiple first elements originating from the received signal received by the same receiving antenna element, a noise component common to these multiple first elements can be extracted. Then, by dividing each of the multiple first elements by the extracted noise component, the element from which the noise component has been removed can be calculated.

[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 that includes the multiple elements calculated.

[0097] Thus, the second complex transfer function calculation 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 function obtained for each of the S subcarriers and each of the N×M combinations as elements in an N×M×S three-dimensional array. The predetermined process involves calculating the amplitude average of a plurality of first elements including the 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.

[0098] In this embodiment, the amplitude average of multiple first elements aligned in the direction of the transmitting antenna element of the first complex transfer function matrix was used to calculate the second complex transfer function matrix. However, the amplitude average of multiple first elements aligned in the direction of the subcarrier 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 being processed and one subcarrier corresponding to the element being processed. Alternatively, the multiple first elements for calculating the amplitude average may be S elements obtained for one receiving antenna element corresponding to the element being processed and one transmitting antenna element corresponding to the element being processed. Alternatively, the multiple first elements for calculating the amplitude average may be S × M elements obtained for one receiving antenna element corresponding to the element being processed.

[0099] Furthermore, 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 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 of both.

[0100] In this embodiment, the amplitude average uses all of the multiple first elements for the amplitude average of the first complex transfer function in the direction of the transmitting antenna element or the subcarrier. However, the average value of some elements (i.e., any number (two or more)) of multiple first elements aligned in the direction of the transmitting antenna relative to the element being processed, or multiple first elements aligned in the direction of the subcarrier relative to the element being processed, or multiple first elements aligned planarly in the direction of the transmitting antenna and subcarrier relative to the element being processed, may also be used.

[0101] In this embodiment, the second complex transfer function matrix is ​​calculated based on the first complex transfer function matrix after the first complex transfer function matrix has been calculated. However, the order of calculation may be reversed. That is, the first complex transfer function matrix may be calculated based on the second complex transfer function matrix after the second complex transfer function matrix has been calculated.

[0102] [Third complex transfer function calculation unit 170] Figure 8 is a schematic diagram illustrating an example of the third error, and Figure 9 is a schematic diagram showing the relationship between the third error and the channel.

[0103] The third complex transfer function calculation unit 170 receives the channel 630 obtained from the 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. Figure 9 illustrates the phase error that requires calibration.

[0104] When signals of different frequencies propagate through space and are received, the amount by which the transmitted signal 310 undergoes phase rotation 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 inter-antenna distance). The three transmitted waves 750-A, 750-B, and 750-C in Figure 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 diverge as the propagation distance increases (760-B, 760-C). For this reason, the inter-antenna distance can be calculated by inversely determining the phase difference by transmitting and receiving signals of multiple known frequencies and measuring the phase difference. However, the phase difference actually measured includes not only the effect of spatial propagation between the transmitting antenna unit 100 and the receiving antenna unit 130, but also errors due to the phase characteristics of the internal circuits of the transmitter and receiver, antennas, etc. (hereinafter referred to as the third error 610). Therefore, in order to correctly measure the inter-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 from the measurement. meas And the ideal channel h 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 can be determined by calculating the difference between the two values. This applies not only to estimating the distance between antennas, but also to estimating the distance between the estimation device 101 and the living organism 20.

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

[0107] The third complex transfer function calculation unit 170 calculates the complex transfer function corresponding to the direct wave 200 by, for example, using a method employing the Fourier transform, performing a Fourier transform on the second complex transfer function with respect to the observation time (slow time) and extracting only specific frequency components. The third complex transfer function calculation unit 170 extracts an arbitrary frequency component, for example, a 0Hz frequency component, 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 the 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 the ideal channel 600 between the antenna elements, H, based on the pre-inputted inter-antenna distance 620 between the transmitting antenna element and the receiving antenna element. ideal The input antenna distance d is, for example, a value obtained by the user actually measuring the distance between the transmitting antenna element and the receiving antenna element. Here H ideal H is a complex matrix with S elements, where H is the ideal channel 600 of the s-th subcarrier. ideal (s) is calculated using equation 6.

[0109]

number

[0110] Here d nm H represents the distance between the m-th transmitting antenna and the n-th receiving antenna, and k(s) represents the wavenumber of the s-th subcarrier. Thus, Hideal is an ideal complex transfer function between the transmission antenna element and the reception antenna element obtained based on the antenna-to-antenna distance 620 between the transmission antenna element and the reception antenna element.

[0111] Next, 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 H ideal which is the ideal channel 600, and the time response complex transfer function H0 corresponding to the direct wave 200. The third complex transfer function calculation unit 170 calculates H ideal by calculating the difference between H cal which is the ideal channel 600, and the time response complex transfer function H0 corresponding to the direct wave 200, to calculate the correction value H cal_nm The correction value h

[0112]

Equation

[0113] Finally, the third complex transfer function calculation unit 170 calculates a third complex transfer function matrix based on the correction value H cal The third complex transfer function between the m-th transmission antenna element and the n-th reception antenna element at the s-th subcarrier is calculated by Equation 8.

[0114]

Equation

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

[0116] In this way, the third complex transfer function calculation unit 170 calculates an offset value (correction value) with respect to the 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 calculation unit 170 converts the second complex transfer function matrix into a frequency response matrix or frequency response vector and extracts the frequency response matrix or frequency response vector corresponding to the direct wave between the transmitting antenna unit 100 and the receiving antenna unit 130. The third complex transfer function calculation unit 170 calculates an ideal complex transfer function corresponding to the direct wave, and calculates a correction value as an offset value to correct the phase error in the S second elements for each N×M combination in the second complex transfer function matrix based on the ideal complex transfer function and the frequency response matrix or frequency response vector. The third complex transfer function calculation unit 170 calculates a third complex transfer function matrix with the phase error corrected based on the correction value.

[0117] In this embodiment, the time-response complex transfer function H0 corresponding to the direct wave 200 is calculated by performing a Fourier transform. However, it may also be calculated using the high-speed processing method that does not require a Fourier transform, as described in Patent Document 2.

[0118] Furthermore, in this embodiment, the time-response complex transfer function H0 corresponding to the direct wave 200 is calculated by performing a Fourier transform, but the elements h of the time-response complex transfer function 0_nm (s) is an element h'' of the second complex transfer function matrix. nmThe third complex transfer function may be calculated by sorting the real and imaginary components within an arbitrary range at (t,s), for example, in descending (or ascending) order, extracting the 10% to 90% values ​​from the sorted components, averaging them in the time direction, and dividing by the calculated average value of the elements of the second complex transfer function matrix. In other words, the third complex transfer function calculation unit 170 calculates the average value obtained by averaging all or more third elements of the second complex transfer function matrix in the real and imaginary directions, respectively. The third complex transfer function calculation unit 170 calculates an ideal complex transfer function corresponding to the direct wave between the transmitting antenna unit 100 and the receiving antenna unit 130, and calculates a correction value as the offset value to correct the phase error in the 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 with the phase error corrected based on the correction value.

[0119] Here, the third complex transfer function calculation unit 170 may further use an MMSE filter that emphasizes the direct wave component as a reference signal using an adaptive array based on the least squares error (MMSE) for the time direction of the calculated third complex transfer function. In other words, the third complex transfer function calculation 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 the reference signal, to the second complex transfer function matrix or the third complex transfer function matrix.

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

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

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

[0123] For example, using the Fourier transform method, by performing a Fourier transform on the third complex transfer function matrix with respect to the observation time (slow time) and extracting only specific frequency components, it is possible to calculate the biocomponent transfer function matrix for each of the multiple frequency components that may include the effects of biological activity, for example, between 0.1 Hz and 3 Hz.

[0124] Here, Figure 10 shows the relationship between frequency and phase of the biocomponent transfer function matrix. The solid line 800 represents how the phase of each component of the biocomponent transfer function matrix varies with the subcarrier frequency when the biological organism 20 is located at a certain position. As the biological organism 20 approaches the transmitting antenna 100 or the receiving antenna 130 from the above position, the path length of the radio waves reflected by the biological organism 20 shortens, so the slope of the graph becomes gentler, as shown by the dashed line 810. In principle, the distance to the Time of Flight (ToF) or the biological organism can be estimated from the slope of this graph. Specifically, by further performing an inverse Fourier transform of this biocomponent transfer function matrix in the subcarrier direction to obtain the time-domain biocomponent transfer function matrix, the time from when the signal containing the biological components is transmitted from the transmitting antenna until it is received by the receiver can be determined.

[0125] Figure 11 shows the relationship between time (column direction of the matrix) and phase of the time-domain biocomponent transfer function matrix. The phase changes of solid line 800 and dashed line 810 in Figure 10 appear as peaks shown by solid line 910 and dashed line 920, respectively. However, the time resolution Δt obtained here is expressed by equation 9 using the bandwidth B of the subcarriers.

[0126]

number

[0127] For example, with a bandwidth of 20 MHz, the temporal resolution is equivalent to 0.5 μs, which translates to a distance resolution of approximately 15 m, making it impractical for real-world use.

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

[0129]

number

[0130] [Estimation part 190] The estimation unit 190 calculates the biological correlation matrix R calculated by the biological correlation matrix calculation unit 180. f Distance and angle measurement are performed using the MUSIC method. In other words, the estimation unit 190 uses the biocorrelation matrix R f Decompose the signal into its eigenvalues ​​and obtain the vector U corresponding to the signal. S and the eigenvector U corresponding to the noise N We calculate the following. Here, the eigenvectors corresponding to the signal are the vectors from the first eigenvector up to the number of objects being detected; for example, if there is one object, there is only the first eigenvector. Also, the eigenvectors corresponding to the signal are the k eigenvectors from the first to the kth eigenvector if, for example, there are k objects (k is a natural number greater than or equal to 2). Furthermore, the eigenvectors corresponding to the noise refer to eigenvectors other than those corresponding to the signal.

[0131] Using the eigenvectors obtained as described above, the MUSIC spectrum P is determined according to the following equation. MUSIC Calculate (x,y).

[0132]

number

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

[0134]

number

[0135] Here d nm (x, y) represents the sum of the distance between coordinate (x, y) and the nth transmitting antenna element and the distance between coordinate (x, y) and the mth receiving antenna element, and λ(s) represents the wavelength of the sth subcarrier. The MUSIC spectrum P obtained in this way. MUSIC The position of organism 20 is estimated to be the point (x, y) at which it takes a maximum value.

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

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

[0138] Furthermore, in this embodiment, the estimation unit 190 estimates the position of the living organism 20, but it may also estimate the distance between the estimation device 101 and the living organism 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 Figure 12. The sum of the distance a (first distance) between the transmitting antenna element and the living organism 20, and the distance b (second distance) between the receiving antenna element and the living organism 20, from any point (x, y) on the maximum ellipse 1010 with respect to the transmitting and receiving antennas (third distance) is calculated by Equation 13.

[0139]

number

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

[0141]

number

[0142] The MUSIC spectrum P obtained in this manner MUSIC The value l at which (l) takes its maximum corresponds to the sum of the distance a (first distance) between the transmitting antenna unit 100 and the living organism 20, and the distance b (second distance) between the receiving antenna unit 130 and the living organism 20 (third distance) in Figure 12.

[0143] Figure 12 is a schematic diagram showing the positional relationship between the living organism, the transmitting antenna unit, and the receiving antenna unit, as well as the position of the living organism, in MIMO. In Figure 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, Figure 12 is an example of MIMO.

[0144] In this way, the estimation unit 190 uses the bio-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 living organism 20 and the second distance between the receiving antenna unit 130 and the living organism 20.

[0145] In this embodiment, the estimation unit 190 estimated the biological position using equation 13. However, the position of the biological 20 may also be estimated using equation 16, where the sum of the estimated distance a (first distance) between the transmitting antenna unit 100 and the biological 20, and the distance b (second distance) between the receiving antenna unit 130 and the biological 20 is the third distance L, and the first angle θ is used to estimate the position of the biological 20.

[0146]

number

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

[0148]

number

[0149] As will be described later, the estimation unit 190 may also estimate the position of the living organism 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 organism 20, and the distance b (second distance) between the receiving antenna unit 130 and the living organism 20 as the third distance L.

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

[0151] Figure 13 is a schematic diagram showing the positional relationship between the living organism, the transmitting antenna unit, and the receiving antenna unit, as well as the position of the living organism, in a MISO (Multiple Imaging System). In Figure 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, Figure 13 is an example of a MISO.

[0152] The MUSIC spectrum P obtained in this manner MUSIC The value l at which (l) takes its maximum corresponds to the sum of the distance a (first distance) between the transmitting antenna unit 100 and the living organism 20, and the distance b (second distance) between the receiving antenna unit 130 and the living organism 20 (third distance) in Figure 13. In this way, the estimation unit 190 uses the biological correlation matrix calculated for each of the multiple subcarriers to estimate the third distance, which is the sum of the first distance between the transmitting antenna unit 100 and the living organism 20 and the second distance between the receiving antenna unit 130 and the living organism 20.

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

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

[0155] Figure 14 is a flowchart showing the estimation process of the estimation device in Embodiment 1.

[0156] The estimation device 101 calculates the complex transfer function for the 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 fluctuations between the transmitting unit 110 and the receiving unit 140, or the timing fluctuations of the digital-to-analog conversion of the transmitted signal 310 or the analog-to-digital conversion of the received signal 320 (S200).

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

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

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

[0161] The details of the processing at each step are omitted here, as they are included in the description of the configuration of the estimation device 101.

[0162] [Effects, etc.] The estimation device 101 according to this embodiment is a device for estimating the internal error of reception, and comprises a transmission signal generation unit 120, a transmission antenna unit 100, a transmission unit 110, a receiving antenna unit 130, a receiving 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 of 2 or more) subcarrier signals are modulated. The transmission antenna unit 100 has M (M is a natural number of 1 or more) 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 receiving antenna unit 130 has N (N is a natural number of 1 or more) receiving antenna elements. The receiving unit 140 observes the received signals received by each of the N receiving antenna elements, which include reflected signals resulting from the reflection or scattering of multicarrier signals transmitted from each of the M transmitting antenna elements by the living organism 20, for a first period corresponding to the period derived from the activity of the living organism 20. Using the multiple received signals observed in the first period, the receiving unit 140 calculates multiple complex transfer functions representing the propagation characteristics between the transmitting antenna elements and the receiving antenna elements for each of the N × M combinations, which are combinations of each of the M transmitting antenna elements and each of the N receiving antenna elements, for each of the S subcarriers corresponding to the S subcarrier signals. 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 in a 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 in an N × M × S three-dimensional array. The prescribed process involves calculating the amplitude average of multiple first elements, including the element to be processed, and then dividing the element to be processed by the amplitude average. The multiple first elements are included in S × M elements obtained for one receiving antenna element corresponding to the element to be processed.

[0163] According to this method, a predetermined process is performed for each of the N×M×S elements in the first complex transfer function matrix, which involves calculating the amplitude average of multiple first elements that are included in the S×M elements obtained for one receiving antenna element corresponding to the element to be processed, and dividing the element to be processed by the amplitude average. As a result, the first error introduced to the received signal by each receiving antenna element can be reduced. Therefore, the position of the living organism 20 can be estimated with high accuracy.

[0164] Furthermore, in the estimation device 101 according to this embodiment, 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.

[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 being processed and one subcarrier corresponding to the element being processed.

[0166] Furthermore, in the estimation device 101 according to this embodiment, 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.

[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 being processed and one transmitting antenna element corresponding to the element being processed.

[0168] Furthermore, 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 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 the 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 reduces the third error relative to the reference phase, allowing for more accurate estimation of the position of the biological organism 20.

[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 frequency response vector and extracts the frequency response matrix or 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 correction values ​​as offset values ​​to correct the phase error in the 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 frequency response vector. The matrix calculation unit 145 calculates a third complex transfer function matrix with the phase error 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 organism 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 obtained 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. The matrix calculation unit 145 calculates an ideal complex transfer function corresponding to the direct wave between the transmitting antenna unit 100 and the receiving antenna unit 130, and calculates a correction value as an offset value to correct the phase error 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 average value. The matrix calculation unit 145 calculates a third complex transfer function matrix with the phase error corrected based on the correction value.

[0175] Therefore, phase errors in the subcarrier direction can be eliminated, and the distance from the estimation device 101 to the living organism 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, which is set as a reference signal for the direct wave between the transmitting antenna unit 100 and the receiving antenna unit 130, 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 organism 20 can be measured with higher accuracy.

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

[0179] This makes it possible to reduce the first error, which is a component corresponding to at least one of (1) clock fluctuations between the transmitter, consisting of a transmitting signal generation unit and a transmitting unit that transmit signals from the transmitting antenna unit, and the receiver, consisting of a receiving unit that receives signals from the receiving antenna unit, and (2) timing fluctuations in the digital-to-analog conversion of the transmitted signal or the analog-to-digital conversion of the received signal. Therefore, the position of the living organism 20 can be estimated with higher accuracy.

[0180] Furthermore, in the estimation device 101 according to this embodiment, M and N are 2 or greater. 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 organism 20 from a first angle which is the direction of the living organism 20 as seen from the M transmitting antenna units 100 and a second angle which is the direction of the living organism 20 as seen from the N receiving antenna units 130.

[0181] Therefore, the position of the living organism 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 more, 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, which is the sum of the first distance between the transmitting antenna unit 100 and the living organism 20 and the second distance between the receiving antenna unit 130 and the living organism 20, and estimates a first angle, which is the direction of the living organism 20 as seen from the transmitting antenna unit 100, and estimates the position of the living organism 20 from the third distance and the first angle.

[0183] Therefore, the position of the living organism 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, second distance, first angle, and second angle using one of the following methods: MUSIC (Multiple Signal Classification) method, beamformer method, and Capon method.

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

[0186] Thus, according to this embodiment, the position (coordinates) of the living organism 20, the distance between the transmitting antenna unit 100 and the receiving antenna unit 130 and the living organism 20, and the direction (angle) in which the living organism 20 is located relative to the transmitting antenna unit 100 and the receiving antenna unit 130 can be estimated using the estimation device 101 with a MIMO or MISO configuration.

[0187] As described above, this disclosure makes it possible to realize an estimation device, estimation method, and program that can estimate the distance and location of a living organism using wireless signals in a short time and with high accuracy.

[0188] (Embodiment 2) Embodiment 2 describes a method for detecting living organisms in the case of a SIMO (Single Input Multiple Output) system where there is a single transmitting antenna and multiple receiving antennas. The same method is also applicable to a SISO (Single Input Single Output) system where both the transmitting and receiving antennas are single.

[0189] [Configuration of Estimation Device 1201] Figure 15 is a block diagram showing an example of the configuration of the estimation device 1201 in Embodiment 2.

[0190] The estimation device 1201 shown in Figure 15 comprises a transmitting antenna unit 1200, a transmitting unit 1210, a transmitting signal generation unit 1220, a receiving antenna unit 1230, a receiving unit 1240, a matrix calculation unit 1245, a biocorrelation matrix calculation unit 1280, and an estimation unit 1290. The matrix calculation unit 1245 has a first complex transfer function calculation unit 1250, a second complex transfer function calculation unit 1260, and a third complex transfer function calculation unit 1270. The estimation device 1201 estimates the position of the living organism 20.

[0191] [Transmitting antenna section 1200] The transmitting antenna unit 1200 has one transmitting antenna element. As described above, the transmitting antenna element transmits a multi-carrier signal (transmitted wave) generated by the transmitting unit 1210, which will be described later.

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

[0193] Furthermore, the signal generated by the transmission signal generation unit 1220 may be shared with the signal used for communication. In other words, the transmission signal used to sense the biological organism 20 may be used exclusively for sensing the biological organism 20, or it may be used for both sensing the biological organism 20 and information communication.

[0194] [Transmitter 1210] The transmitting unit 1210 processes the signal generated by the transmitting signal generation unit 1220 to generate a transmission wave. This processing includes, for example, upconversion (converting the signal from the IF (Intermediate Frequency) band to the RF (Radio Frequency) band) and amplification (amplifying the signal to an appropriate transmission level). The transmitting unit 1210 outputs the processed multi-carrier signal to the transmitting antenna unit 1200, causing the transmitting antenna unit 1200 to transmit the signal. As a result, the multi-carrier signal is transmitted from a single transmitting antenna element in the transmitting antenna unit 1200.

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

[0196] [Receiver 1240] The receiving unit 1240 observes the received signal 320, which is received by N receiving antenna elements and includes a reflected signal, which is a multi-carrier signal transmitted from one transmitting antenna element and reflected or scattered by the living organism 20, for a first period corresponding to a period derived from the activity of the living organism 20. The period derived from the activity of the living organism is a period derived from the living organism (living fluctuation period) that is half a period or longer of any of the periods of respiration, heartbeat, or body movement of the living organism 20.

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

[0198] The receiving unit 1240 further calculates multiple complex transfer functions representing the propagation characteristics between the transmitting antenna element and the receiving antenna element for each subcarrier, based on the multiple IQ symbols observed during the first period.

[0199] Furthermore, the receiving unit 1240 may continuously observe the received signal 320 received by the receiving antenna unit 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 for each of the multiple subcarriers that each of the multiple subcarrier signals corresponds to, for each of the N combinations of one transmitting antenna element and N receiving antenna elements.

[0201] The receiving unit 1240 calculates an S×N complex transfer function for the estimation device 1201 that represents the propagation characteristics between each transmitting antenna element and each receiving antenna element. The receiving unit 1240 may then generate a complex transfer function matrix having S×N elements. The calculated complex transfer function matrix includes reflected waves that do not pass through the living organism 20, such as direct waves and reflected waves originating from fixed objects.

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

[0203] Figure 16 is a diagram illustrating the propagation characteristics at each timing of SIMO.

[0204] As described above, the propagation characteristic H has a complex transfer function with two types of parameters: one for each receiving antenna element and one for each subcarrier. In other words, a different complex transfer function is calculated for each of the different receiving antenna elements and each of the different subcarriers.

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

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

[0207]

number

[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 the clock fluctuations between the transmitting unit 1210 and the receiving unit 1240, or the timing fluctuations of the digital-to-analog conversion of the transmitted signal 310 or the analog-to-digital conversion of the received 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 certain observation time or the entire observation time, and calculates the first complex transfer function matrix from the first eigenvectors. The correlation matrix R in the transmission direction is obtained from the propagation characteristics H(t). R and the correlation matrix R of the transmission direction T These are calculated as shown in Equations 18 and 19, respectively.

[0210]

number

[0211]

number

[0212] Here, t0 represents the instantaneous observation time.

[0213] The first complex transfer function calculation unit 1250 performs eigenvalue decomposition on the transmit correlation matrix and the receive correlation matrix to calculate the first transmit eigenvector v1 and the first receive eigenvector u1. The elements of the first complex transfer function, which is obtained when the s-th subcarrier is transmitted from the transmitting antenna and received by the n-th receiving antenna, are calculated using equation 20.

[0214]

number

[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 that includes the multiple elements calculated.

[0216] In this embodiment, the case where there are two or more receiving antenna elements has been described, but in the case where there is only 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 the present embodiment, the second complex transfer function calculation unit 1260 performs a predetermined process for suppressing a second error 400, which is an in-receiver error, by using the amplitude average of a plurality of first elements arranged in the first one-dimensional direction 500 from the first complex transfer function calculation unit 1250. In the present 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 in-receiver error, is suppressed based on the amplitude average of a plurality of first elements in the sub-carrier direction as the first one-dimensional direction 500. Among the elements of the second complex transfer function matrix, the element of the second complex transfer function matrix transmitted from the transmission antenna by the s-th sub-carrier and received by the n-th receiving antenna is represented by Equation 21.

[0218]

Equation

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

[0220] In the present embodiment, for the amplitude average in the sub-carrier direction of the first complex transfer function, all of the plurality of first elements are used. However, a plurality of first elements arranged in the transmission antenna direction with respect to the element to be processed, or a plurality of first elements arranged in the sub-carrier direction with respect to the element to be processed, or a part of a plurality of first elements (that is, an arbitrary number (two or more)) arranged two-dimensionally in the transmission antenna direction and sub-carrier direction with respect to the element to be processed may be used as the average value.

[0221] In the present embodiment, the second complex transfer function matrix is calculated by using the amplitude average of a plurality of first elements. However, it may be calculated by using the phase average of the 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 the plurality of first elements or the average value of both.

[0222] In this embodiment, it is assumed that 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 calculation order may be reversed. That is, 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 the phase error in the frequency direction.

[0224] In the third complex transfer function calculation unit 1270, the third error 610 which is the phase error in the sub-carrier direction is corrected. The direct wave component in the second complex transfer function received from the second complex transfer function calculation unit 1260 is extracted. As methods for obtaining the biological component from the complex transfer function recorded in time series, there are the Fourier transform disclosed in Patent Document 1 and the method using differential information disclosed in Patent Document 2.

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

[0226] Next, the third complex transfer function calculation unit calculates the ideal channel 600H between the antenna elements based on the antenna element distance 620 between the transmission antenna element and the reception antenna element input in advance. ideal The input antenna element distance d is, for example, a value obtained by actually measuring the distance between the transmission antenna element and the reception antenna element by the user. Here, Hideal H is a complex matrix with S subcarrier elements and an ideal channel of 600. ideal This is calculated using (Equation 22).

[0227]

number

[0228] Here d n H represents the distance between the transmitting antenna and the nth receiving antenna, and k(s) represents the wavenumber of the sth subcarrier. Thus, H ideal This is the ideal complex transfer function between the transmitting and receiving antenna elements, obtained based on the inter-antenna distance of 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 Based on the time-response complex transfer function H0 corresponding to the direct wave 200, a correction value is calculated to correct the third error 610, which is the phase error in the subcarrier direction. The third complex transfer function calculation unit 1270 calculates the H0 of the ideal channel 600. ideal Then, by calculating the difference between this and the time-response complex transfer function H0 corresponding to the direct wave 200, the correction value H cal The correction value h for the third error 610 between the transmitting antenna element and the nth receiving antenna element in the sth subcarrier is calculated. cal_ns This is calculated using Equation 23.

[0230]

number

[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. The third complex transfer function between the transmitting antenna element and the nth receiving antenna element in the sth subcarrier is calculated using Equation 20.

[0232]

number

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

[0234] In this embodiment, the time-response complex transfer function H0 corresponding to the direct wave 200 is calculated by performing a Fourier transform. However, it may also be calculated using the high-speed processing method that does not require a Fourier transform, as described in Patent Document 2.

[0235] Furthermore, in this embodiment, the time-response complex transfer function H0 corresponding to the direct wave 200 is calculated by performing a Fourier transform, but the elements h of the time-response complex transfer function 0_ns h'' is an element of the second complex transfer function matrix. ns In (t), the real and imaginary components may be sorted in ascending (or descending) order, the 10% to 90% values ​​of the sorted components are extracted, the average is calculated over time, and the elements of the second complex transfer function matrix are divided by the calculated average value.

[0236] Here, the third complex transfer function calculation unit 1270 may use an MMSE filter that emphasizes the direct wave component as a reference signal using an adaptive array based on the least squares error (MMSE) for the time direction of the calculated third complex transfer function. In other words, the third complex transfer function calculation 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 the reference signal, to the second complex transfer function matrix or the third complex transfer function matrix.

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

[0238] [Biological correlation matrix calculation unit 1280] For each of the S×N combinations, the biological correlation matrix calculation unit 1280 sequentially records a plurality of complex transfer function matrices calculated by the third complex transfer function calculation unit 1270 in a time series that is the order in which the plurality of received signals 320 were observed. Then, for each of the S×N combinations, the biological correlation matrix calculation unit 1280 extracts components related to the living body 20 from the third complex transfer function matrix or the fourth complex transfer function matrix that was observed during the first period sequentially recorded in the time series and suppresses the first error 210, the second error 400, and the third error 610, thereby calculating a biological component transfer function matrix expressed by an S×N-dimensional matrix.

[0239] Here, the biological component transfer function matrix is obtained by extracting the reflected wave or scattered wave (biological component) that has passed through the living body 20 and is included in the received signal 320. As methods for obtaining biological components from the third complex transfer function recorded in time series, there are the Fourier transform disclosed in Patent Document 1 and the method using differential information disclosed in Patent Document 2.

[0240] For example, in the method using the Fourier transform, the third complex transfer function matrix is Fourier-transformed with respect to the observation time (slow time) and only specific frequency components are extracted, whereby a biological component transfer function matrix can be calculated for each of a plurality of frequency components included in a frequency range that may include the influence of the activity of the living body, for example, from 0.1 Hz to 3 Hz.

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

[0242] [Equation]

[0243] For example, with a bandwidth of 20 MHz, the temporal resolution is equivalent to 0.5 μs, which translates to a distance resolution of approximately 15 m, making it impractical for real-world use.

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

[0245]

number

[0246] [Estimation part 1290] The estimation unit 1290 calculates the biological correlation matrix R calculated by the biological correlation matrix calculation unit 1280. f Distance and angle measurements are performed using the MUSIC method.

[0247] In other words, the estimation unit 1290 calculates the biological correlation matrix R f Decompose the signal into its eigenvalues ​​and obtain the vector U corresponding to the signal. S and the eigenvector U corresponding to the noise N We calculate the following. Here, the eigenvectors corresponding to the signal are the vectors from the first eigenvector up to the number of objects being detected; for example, if there is one object, there is only the first eigenvector. Also, the eigenvectors corresponding to the signal are the k eigenvectors from the first to the kth eigenvector if, for example, there are k objects (k is a natural number greater than or equal to 2). Furthermore, the eigenvectors corresponding to the noise refer to eigenvectors other than those corresponding to the signal.

[0248] Using the eigenvectors obtained as described above, the MUSIC spectrum P is determined according to the following equation. MUSIC Calculate (x,y).

[0249]

number

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

[0251]

number

[0252] Here d n (x, y) represents the sum of the distance between coordinate (x, y) and the transmitting antenna element and the distance between coordinate (x, y) and the m-th receiving antenna element, and λ(s) represents the wavelength of the s-th subcarrier. The MUSIC spectrum P obtained in this way. MUSIC The position of organism 20 is estimated to be the point (x, y) at which it takes a maximum value.

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

[0254]

number

[0255] Here, a(l) represents the steering vector and is calculated as shown in equation 30.

[0256]

number

[0257] The MUSIC spectrum P obtained in this manner MUSIC The value l at which (l) takes its maximum corresponds to the sum of the distance a (first distance) between the transmitting antenna unit 1200 and the living organism 20, and the distance b (second distance) between the receiving antenna unit 1230 and the living organism 20 (third distance) in Figure 17.

[0258] Figure 17 is a schematic diagram showing the positional relationship between the living organism, the transmitting antenna unit, and the receiving antenna unit, as well as the position of the living organism, in a SIMO. In Figure 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, Figure 17 is an example of a SIMO.

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

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

[0261]

number

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

[0263]

number

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

[0265] Figure 18 is a schematic diagram showing the positional relationship between the living organism, the transmitting antenna unit, and the receiving antenna unit, as well as the position of the living organism, in a SISO (Stand-Up Insulator). In Figure 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, Figure 18 is an example of an SISO.

[0266] The MUSIC spectrum P obtained in this manner MUSIC The value l at which (l) takes its maximum corresponds to the sum of the distance a (first distance) between the transmitting antenna unit 1200 and the living organism 20, and the distance b (second distance) between the receiving antenna unit 1230 and the living organism 20 (third distance) in Figure 18. In this way, the third distance, which is the sum of the first distance between the transmitting antenna unit 1200 and the living organism 20 and the second distance between the receiving antenna unit 1230 and the living organism 20, is estimated using the biological correlation matrix calculated for each of the multiple subcarriers. As a result, the estimation unit 1290 can estimate that the living organism 20 is located on an ellipse 1410 with the transmitting antenna element and the receiving antenna element as foci. The estimation unit 1290 may also estimate the position of the living organism 20 from the intersection of the ellipse by estimating multiple third distances using three or more sets 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 described above will now be explained.

[0268] Figure 19 is a flowchart showing the estimation process of the estimation device in Embodiment 2.

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

[0270] Next, the estimation device 1201 calculates a first complex transfer function matrix that suppresses a first error 210 corresponding to at least one of the clock fluctuations between the transmitter 1210 and the receiver 1240, or the timing fluctuations of the digital-to-analog conversion of the transmitted signal 310 or the analog-to-digital conversion of the received signal 320 (S201).

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

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

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

[0274] The details of the processing at each step are omitted here, as 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 greater. The estimation device 1201 further includes an estimation unit 1290. The estimation unit 1290 uses the third complex transfer function matrix calculated by the matrix calculation unit 1245 to estimate a third distance, which is the sum of the first distance between the transmitting antenna unit 1200 and the living organism 20 and the second distance between the receiving antenna unit 1230 and the living organism 20, and estimates a second angle, which is the direction of the living organism 20 as seen from the receiving antenna unit 1230, and estimates the position of the living organism 20 from the third distance and the second angle.

[0276] Therefore, the position of the living organism 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 uses the third complex transfer function matrix calculated by the matrix calculation unit 145 to estimate the third distance, which is the sum of the first distance between the transmitting antenna unit 1200 and the living organism 20 and the second distance between the receiving antenna unit 1230 and the living organism 20.

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

[0279] Thus, according to this embodiment, the position (coordinates) of the living organism 20, the distance between the transmitting antenna unit 1200 and the receiving antenna unit 1230 and the living organism 20, and the direction (angle) in which the living organism 20 is located relative to the transmitting antenna unit 1200 and the receiving antenna unit 1230 can be estimated using an estimation device with a SIMO and SISO configuration.

[0280] As described above, this disclosure makes it possible to realize an estimation device, estimation method, and program that can estimate the distance and location of a living organism using wireless signals in a short time and with high accuracy.

[0281] To verify the effects of this embodiment, an experimental evaluation was conducted. The experiment is described below.

[0282] [experiment] Figure 20 shows the experimental conditions using the estimation method according to this embodiment.

[0283] Both the transmitting array antenna (Transmitter) and the receiving array antenna (Receiver) shown in Figure 20 are configured as 4x4 MIMO (Multiple Input Multiple Output) antennas using 4-element patch array antennas.

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

[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 set to 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 an OFDM (Orthogonal Frequency Division Multiplexing) signal from channel 1 of the 2.4 GHz band of Wi-Fi (registered trademark), and the channel measurement time was set to 25.6 seconds. During the channel measurement, no one other than the subject was present, and the subject faced the wall on the antenna side, with one person standing at 17 designated points for measurement.

[0286] Figure 21 shows the experimental results using the estimation method according to Embodiment 1.

[0287] In Figure 21, circles indicate estimated points, and squares indicate the actual positions where the subject stood. Furthermore, the MUSIC spectrum P (see Equation 13) for each position in space is shown, indicating that the subject is estimated to be located in positions with colors close to white.

[0288] Figure 22 shows another experimental result using the estimation method according to Embodiment 1. Figure 22 shows the cumulative probability distribution (CDF: Cumulative Distribution Function) of the distance measurement error. The solid line 1510 shows the experimental result using the estimation method according to Embodiment 1, and the dashed line 1520 shows the experimental result using the conventional method.

[0289] In Figure 22, the horizontal axis shows the distance measurement error (in meters), and the vertical axis shows the CDF (Critical Distance Factor) for the distance measurement error. The proposed method yields a CDF value of 0.75 for a distance measurement error of 0.65m, indicating that 75% of measurements fall within an error of 0.65m. In contrast, the conventional method achieves an error of 4.90m for 75% of measurements.

[0290] Therefore, it can be seen that the estimation method according to Embodiment 1 can estimate the 75th percentile of the distance measurement error with a higher accuracy of 4.25 m compared to the conventional method using full MIMO CSI. This demonstrates that this embodiment can estimate the position of a living organism with higher accuracy.

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

[0292] Although an estimation device and estimation method relating to one aspect of this disclosure have been described above based on embodiments, this disclosure is not limited to these embodiments. Without departing from the spirit of this disclosure, various modifications to these embodiments that a person skilled in the art could conceive, or configurations constructed by combining components from different embodiments, are also included within the scope of this disclosure.

[0293] For example, in Embodiments 1 and 2, distance estimation to a living organism 20 or position estimation of a living organism 20 was described as an example, based on the estimation devices 101 and 1201, but the object of estimation is not limited to a living organism 20. It can be applied 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, this disclosure can be implemented not only as a positioning sensor equipped with such characteristic components, but also as an estimation method that uses the characteristic components included in the positioning sensor as steps. It can also be implemented as a computer program that causes a computer to execute each of the characteristic steps included in such a method. And it goes without saying that such a computer program can be distributed via a computer-readable non-temporary recording medium such as a CD-ROM or via a communication network such as the Internet. [Industrial applicability]

[0295] This disclosure can be used in positioning sensors and distance estimation methods that estimate the distance to or the position of a living organism using wireless signals, and in particular in distance measuring sensors and direction estimation methods that are mounted on measuring instruments that measure the distance or position to living organisms, including living organisms and machines, home appliances that perform control according to the distance or position to living organisms, and monitoring devices that detect the intrusion of living organisms. [Explanation of symbols]

[0296] 20 Living organisms 30 Target space 101, 1201 Estimation device 100, 1200 Transmitting Antenna Section 110, 1210 Transmitter 120, 1220 Transmit signal generation unit 130, 1230 Receiving antenna section 140, 1240 Receiver 145, 1245 Matrix calculation section 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 Biological correlation matrix calculation unit 190, 1290 Estimation part 200 direct wave 210 First error 310 Transmit signal 320 Received signal 330 Direct Wave + Bio-derived Components 400 Second error 500 First dimension direction 600 ideal channels 610 Third error 620 Antenna distance 630 channels Phase of each subcarrier signal transmitted from the 750-A, 750-B, and 750-C transmitting antennas. Phase shift of signals with different frequencies transmitted from the 760-B and 760-C transmitting antenna sections. 800, 810 Phase change of the complex transfer function matrix with respect to frequency 910 Solid line 920 dashed line Ellipses where living organisms may exist, determined by the third distance: 1010, 1310, 1410 1510 Solid line 1520 Dashed line

Claims

1. A transmission signal generation unit that generates a multicarrier signal in which S subcarrier signals (where S is a natural number greater than or equal to 2) are modulated, A transmitting antenna section having M transmitting antenna elements (where M is a natural number greater than or equal to 1), A transmitting unit that processes the multi-carrier signal and outputs it to the transmitting antenna unit, thereby causing the multi-carrier signal to be transmitted to the transmitting antenna unit, A receiving antenna section having N receiving antenna elements (where N is a natural number greater than or equal to 1), A receiving unit that observes the received signals received by each of the N receiving antenna elements, which include reflected signals resulting from the reflection or scattering of the multi-carrier signals transmitted from each of the M transmitting antenna elements by the living organism, for a first period corresponding to a period derived from the activity of the living organism, and uses the plurality of received signals observed in the first period to calculate a plurality of complex transfer functions representing the propagation characteristics between the transmitting antenna element and the receiving antenna element for each of the N × M combinations, which are combinations of each of the M transmitting antenna elements and each of the N receiving antenna elements, for each of the S subcarriers corresponding to each of the S subcarrier signals, (i) A matrix calculation unit that calculates a second complex transfer function matrix by performing a predetermined process on each of the N × M × S elements in a first complex transfer function matrix that includes the complex transfer function 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) calculates an offset value with respect to the 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, The predetermined process involves calculating the amplitude average of a plurality of first elements, including the element to be processed, and dividing the element to be processed by the amplitude average. The plurality of first elements are included in 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 aforementioned plurality of first elements are the S × M elements. The estimation device according to claim 1.

5. The matrix calculation unit, The second complex transfer function matrix is ​​converted into a frequency response matrix or frequency response vector, and the frequency response matrix or frequency response vector corresponding to the direct wave between the transmitting antenna and the receiving antenna is extracted. An ideal complex transfer function corresponding to the direct wave is calculated, and based on the ideal complex transfer function and the frequency response matrix or frequency response vector, a correction value is calculated as the offset value to correct the phase error in the S second elements of each of the N × M combinations in the second complex transfer function matrix. The third complex transfer function matrix is ​​calculated by correcting the phase error based on the correction value. The estimation device according to claim 4.

6. The matrix calculation unit, The average value is calculated by averaging all or more third elements of the second complex transfer function matrix in the real part direction and the imaginary part direction, An ideal complex transfer function corresponding to the direct wave between the transmitting antenna section and the receiving antenna section is calculated, and based on the ideal complex transfer function and the average value, a correction value for correcting the phase error in the S second elements of each of the N × M combinations in the second complex transfer function matrix is ​​calculated as the offset value. The third complex transfer function matrix is ​​calculated by correcting the phase error based on the correction value. The estimation device according to claim 4.

7. The matrix calculation unit further, The fourth complex transfer function matrix is ​​calculated by applying a time-direction MMSE (Minimum Mean Square Error) filter, which is set as the reference signal for the direct wave between the transmitting antenna and the receiving antenna, 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 from the N×M×S complex transfer functions, which is the set of complex transfer functions obtained for each of the S subcarriers and each of the N×M combinations, and is a direct wave component that does not pass through the biological body, and has N×M×S corrected elements obtained by dividing all the elements of the N×M×S complex transfer functions. The estimation device according to claim 1.

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

11. The aforementioned M and N are 1, The system includes an estimation unit that uses the third complex transfer function matrix calculated by the pre-matrix calculation unit to estimate a third distance, which is the sum of the first distance between the transmitting antenna unit and the living organism and the second distance between the receiving antenna unit and the living organism. 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 one of the following methods: MUSIC (Multiple Signal Classification) method, beamformer method, and Capon method. The estimation device according to claim 10.

13. An estimation method using an estimation device comprising a transmitting antenna section having M transmitting antenna elements (where M is a natural number of 1 or more) and a receiving antenna section having N receiving antenna elements (where N is a natural number of 1 or more), A multicarrier signal is generated by modulating S subcarrier signals (where S is a natural number greater than or equal to 2). By processing the multi-carrier signal and outputting it to the transmitting antenna unit, the multi-carrier signal is transmitted to the transmitting antenna unit. The received signals received by each of the N receiving antenna elements, which include reflected signals resulting from the reflection or scattering of the multi-carrier signals transmitted from each of the M transmitting antenna elements by the living organism, are observed for a first period corresponding to a period derived from the activity of the living organism. Using the multiple received signals observed during the first period, for each of the N × M combinations, which are combinations of each of the M transmitting antenna elements and each of the N receiving antenna elements, a complex transfer function representing the propagation characteristics between the transmitting antenna element and the receiving antenna element in that combination is calculated for each of the S subcarriers that each of the S subcarrier signals corresponds to. The complex transfer function obtained for each of the S subcarriers and each of the N × M combinations is included as an element in the N × M × S three-dimensional array of the first complex transfer function matrix, and a predetermined process is performed on each of the N × M × S elements to calculate the second complex transfer function matrix. An offset value relative to the reference phase calculated from the positional relationship between the transmitting antenna section and the receiving antenna section is calculated, and a third complex transfer function matrix is ​​calculated by correcting the second complex transfer function matrix based on the offset value. The predetermined process involves calculating the amplitude average of a plurality of first elements, including the element to be processed, and dividing the element to be processed by the amplitude average. The plurality of first elements are included in 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 described in claim 13.

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