Estimation device, estimation method, and program

Abstract

An estimation device is provided with: a transmission unit (1100) that processes a multicarrier signal and transmits the multicarrier signal to a transmission antenna unit; a transmission antenna unit (1000) comprising M transmission antenna elements; a reception antenna unit (1300) comprising N reception antenna elements; a receiving unit (1400) that observes the received signal for the first period; a first complex variable transfer function calculation unit (1500) that calculates, for each subcarrier of the modulated signal, a plurality of first complex variable transfer functions indicating propagation characteristics between each of the transmission antenna elements and each of the reception antenna elements on the basis of a plurality of reception signals observed during a first period; and a second complex variable transfer function calculation unit (1600) that calculates a second complex variable transfer function by dividing all elements of the first complex variable transfer function by the direct wave component.

Description

Technical Field

[0001] The present disclosure relates to an estimation device, an estimation method, and a program for estimating information related to a living body with high accuracy. Background Art

[0002] As a method for determining a person's location, methods utilizing wireless signals have been discussed (see, for example, Patent Documents 1 to 4). The techniques disclosed in Patent Documents 1, 2, and 3 use differential calculations to analyze components including Doppler shift, thereby estimating the location or status of the person being detected. Patent Documents 4 and 5 disclose Doppler sensors that utilize OFDM (Orthogonal Frequency Division Multiplexing) signals.

[0003] (Prior art literature)

[0004] (Patent Document)

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2015-117972

[0006] Patent Document 2: Japanese Patent Application Laid-Open No. 2017-129558

[0007] Patent Document 3: Japanese Patent Application Publication No. 2018-008021

[0008] Patent Document 4: Japanese Patent Application Laid-Open No. 2012-088279

[0009] Patent Document 5: Japanese Patent Application Laid-Open No. 2012-137340

[0010] Patent Document 6: Japanese Patent Application Laid-Open No. 2006-157663

[0011] Patent Document 7: Japanese Patent Application Laid-Open No. 2001-144722

[0012] (Non-patent literature)

[0013] Non-patent literature 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

[0014] Problems to be solved by the invention

[0015] It has been difficult to estimate information related to a living organism with higher accuracy using conventional methods.

[0016] In view of the above-mentioned circumstances, the present disclosure provides an estimation device capable of estimating information related to a living body with higher accuracy.

[0017] Means for solving problems

[0018] To achieve the above-mentioned object, an estimation device according to one embodiment of the present disclosure comprises: a transmission signal generating unit for generating a multi-carrier signal modulated by a plurality of sub-carrier signals; a transmission antenna unit having M transmission antenna elements, where M is a natural number greater than or equal to 1; a transmission unit for processing the multi-carrier signal and outputting the processed signal to the transmission antenna unit, thereby transmitting the multi-carrier signal from the transmission antenna unit; a reception antenna unit having N reception antenna elements, where N is a natural number greater than or equal to 1; and a reception unit for observing a reception signal for a first period, the reception signal being a reception signal received by each of the N reception antenna elements and including a reflection signal resulting from the multi-carrier signal transmitted from each of the M transmission antenna elements and reflected or scattered by a living body, the first period being equivalent to a period of time corresponding to a period of time from the living body. during a period of activity cycle; a first complex transfer function calculation unit, using the plurality of received signals observed in the receiving unit during the first period, calculates, for each combination of the M transmitting antenna elements and the N receiving antenna elements, i.e., each group of M×N combinations, a plurality of first complex transfer functions representing propagation characteristics between the transmitting antenna element and the receiving antenna element in the combination according to each of the plurality of subcarriers corresponding to the plurality of subcarrier signals; and a second complex transfer function calculation unit, calculating a second complex transfer function by dividing all elements of the first complex transfer function by a direct wave component, wherein the direct wave component is extracted using one or more elements of the first complex transfer function and is a component of the plurality of received signals that does not pass through the biological body.

[0019] Furthermore, in an estimation method according to one embodiment of the present disclosure, a multicarrier signal modulated with a plurality of subcarrier signals is generated, the multicarrier signal is processed and output to a transmitting antenna unit having M transmitting antenna elements, so that the multicarrier signal is transmitted by the transmitting antenna unit, where M is a natural number greater than or equal to 1, and a received signal is observed for a first period, the received signal being a received signal received by each of the N receiving antenna elements constituting the receiving antenna unit, and the received signal being a received signal including a reflected signal resulting from reflection or scattering of the multicarrier signal transmitted from each of the M transmitting antenna elements by a living body, the first period being a period corresponding to a period of activity originating from the living body, where N is a natural number greater than or equal to 1, but M and at least one of N is a natural number greater than 2, using the multiple received signals observed in the first period, for each combination of the M transmitting antenna elements and each of the N receiving antenna elements, that is, each group of M×N combinations, according to each of the multiple subcarriers corresponding to the multiple subcarrier signals, multiple first complex transfer functions representing the propagation characteristics between the transmitting antenna element and the receiving antenna element in the combination are calculated, and a second complex transfer function is calculated by dividing all elements of the first complex transfer function by a direct wave component, wherein the direct wave component is extracted using one or more elements of the first complex transfer function and is a component of the multiple received signals that does not pass through the biological body.

[0020] In addition, these general or specific methods can be implemented by systems, integrated circuits, computer programs or computer-readable recording media such as CD-ROMs, or by any combination of devices, systems, methods, integrated circuits, computer programs and recording media.

[0021] Effects of the Invention

[0022] The present disclosure enables estimation of information related to a living organism with higher accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a block diagram showing an example of the configuration of an estimation device.

[0024] Figure 2 This is a schematic diagram showing how the phase of a received signal changes depending on frequency and distance.

[0025] Figure 3 This is a schematic diagram showing the relationship between phase error and channel.

[0026] Figure 4 It is a schematic diagram showing the relationship between frequency and the inclination of the phase difference.

[0027] Figure 5This is a schematic diagram showing the phase of the time-domain biological component transfer function matrix.

[0028] Figure 6 This is a schematic diagram showing the positional relationship between a living body and the transmitting antenna element and the receiving antenna element, as well as the position of the living body defined by the third distance.

[0029] Figure 7 This is a schematic diagram showing how the position of a living body is estimated by using multiple receiving antenna elements.

[0030] Figure 8 : is a flowchart showing the estimation process of the estimation device.

[0031] Figure 9 : is a flowchart showing the second complex transfer function calculation process.

[0032] Figure 10 3 is a flowchart showing the third complex transfer function calculation process.

[0033] Figure 11 is a flowchart showing the ranging process. DETAILED DESCRIPTION

[0034] (Insights that form the basis of this disclosure)

[0035] As a method for knowing a person's location, etc., a method using wireless signals has been discussed.

[0036] For example, Patent Documents 1 and 2 disclose that a wireless signal is transmitted to a predetermined area, and a plurality of antennas receive the wireless signal reflected by the detection object to estimate the complex transfer function between the transmitting and receiving antennas. The complex transfer function is a complex function that represents the relationship between input and output, and here represents the propagation characteristics between the transmitting and receiving antennas. The number of elements of the 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 that the posture of a living body is estimated using the RCS (Radar Cross Section) obtained from the received power with the same structure as Patent Document 2. RCS is an indicator that represents the area of the object that reflects the transmitted wave, and the RCS of the living body will change in various ways depending on the posture.

[0037] Patent Document 1 also discloses that by analyzing components including Doppler shift using Fourier transform, the position or status of the person being detected can be determined. More specifically, the time variations of the elements of the complex transfer function are recorded, and the time waveform is Fourier transformed. Living organisms such as humans impart a subtle Doppler effect to reflected waves through biological activities such as breathing and heart rate. Therefore, the components including Doppler shift include the influence of humans. Furthermore, components without Doppler shift are not affected by humans, that is, they correspond to reflected waves from fixed objects or direct waves between transmitting and receiving antennas. In other words, by utilizing the components within a specified frequency range in the Fourier transformed waveform, the position or status of the person being detected can be determined.

[0038] The method disclosed in Patent Document 2 records the temporal variations of elements of a complex transfer function and analyzes the resulting differential information to extract components containing Doppler shifts that only include minimal effects from the living body. This differential information can be used to determine the location and status of the person being detected.

[0039] Patent Document 3 discloses an OFDM Doppler radar that transmits pulses using an OFDM signal to detect the Doppler shift of a moving object passing by. Furthermore, Patent Document 4 discloses a fast processing method for OFDM Doppler radar that does not require Fourier transform.

[0040] Furthermore, the technologies disclosed in Patent Documents 6 and 7 improve the accuracy of estimating the complex transfer function between transmit and receive antennas by transmitting OFDM signals. Patent Document 5 discloses averaging the complex transfer function per subcarrier, thereby enabling the selection of the subcarrier with the highest received power, and thereby reducing the noise component of each reception.

[0041] However, because the methods described in Patent Documents 1, 2, and 3 transmit unmodulated waves, they are difficult to apply to commercially available equipment and require dedicated hardware. This means that currently available communication equipment cannot be used, and users must install dedicated hardware in addition to their existing communication devices.

[0042] Furthermore, the methods of Patent Documents 4 and 5 require a steep transmission pulse to achieve sufficient accuracy, which requires a large frequency band. Consequently, the hardware cost is higher than that of ordinary civilian communication devices.

[0043] The technology in Non-Patent Document 1 uses a measuring instrument such as a network analyzer to transmit and receive signals at multiple frequencies, thereby estimating the time of flight (ToF) between the transmitting and receiving antennas, or the distance calculated from ToF. This is similar to distance-measuring sensors based on FMCW (Frequency Modulated Continuous Wave) radar, exploiting the fact that when two signals of different frequencies are transmitted at the same phase, the phase received by the receiving antenna varies depending on the frequency difference of the signals and the distance they travel between the antennas. The technology in Non-Patent Document 1 also improves resolution by performing ToF estimation using the MUSIC (Multiple Signal Classification) algorithm. However, since the transmitter and receiver must operate at the same reference frequency or be synchronized with high precision, it cannot be used with household devices such as wireless LANs. Furthermore, only the distance between antennas can be estimated; for example, it cannot estimate the distance to a living organism without special equipment.

[0044] In light of the above-mentioned circumstances, the inventors of the present disclosure have devised an invention, such as an estimation device, that can utilize existing communication equipment to estimate information related to a living organism with increased accuracy and low cost by utilizing multi-carrier wireless signals, typified by OFDM. The information related to the living organism includes, for example, the distance from the estimation device to the living organism, the direction from the estimation device toward the living organism, the location of the living organism, and an identifier for the living organism.

[0045] That is, the estimation device involved in the first embodiment of the present disclosure includes: a transmission signal generating unit that generates a multi-carrier signal modulated by a plurality of sub-carrier signals; a transmission antenna unit having M transmission antenna elements, where M is a natural number greater than or equal to 1; a transmission unit that processes the multi-carrier signal and outputs the processed signal to the transmission antenna unit, thereby transmitting the multi-carrier signal from the transmission antenna unit; a reception antenna unit having N reception antenna elements, where N is a natural number greater than or equal to 1; and a reception unit that observes a reception signal for a first period, the reception signal being a reception signal received by each of the N reception antenna elements and including a reflection signal resulting from the multi-carrier signal transmitted from each of the M transmission antenna elements and reflected or scattered by a living body, the first period corresponding to an activity of the living body. period of the cycle; a first complex transfer function calculation unit, using the multiple received signals observed by the receiving unit during the first period, calculates, for each combination of the M transmitting antenna elements and the N receiving antenna elements, i.e., each group of M×N combinations, a plurality of first complex transfer functions representing the propagation characteristics between the transmitting antenna element and the receiving antenna element in the combination according to each of the multiple subcarriers corresponding to the multiple subcarrier signals; and a second complex transfer function calculation unit, calculating a second complex transfer function by dividing all elements of the first complex transfer function by a direct wave component, wherein the direct wave component is extracted using one or more elements of the first complex transfer function and is a component of the multiple received signals that does not pass through the biological body.

[0046] Based on this, a second complex transfer function can be calculated that suppresses the frequency phase error and the component corresponding to at least one of (1) and (2), wherein (1) is the clock jitter between a transmitter and a receiver, wherein the transmitter is a transmitter composed of a transmission signal generating unit and a transmission unit that transmits from a transmission antenna unit, and the receiver is a receiver composed of a reception unit that receives via a reception antenna unit, and (2) is the timing jitter of the digital-to-analog conversion of the transmission signal or the analog-to-digital conversion of the reception signal. Therefore, it is possible to estimate information related to a living body in a short time and with high accuracy using wireless signals.

[0047] This configuration uses multi-carrier signals, such as OFDM, for transmission signals, making it possible to implement bioradar using existing communication equipment. For example, OFDM receivers are already common in mobile phones, television receivers, and wireless LAN equipment, reducing costs compared to unmodulated signals.

[0048] The estimation device involved in the second embodiment of the present disclosure is based on the estimation device involved in the first embodiment, and the one or more elements used for extracting the direct wave component include two or more elements corresponding to two or more subcarriers adjacent in frequency among the multiple subcarriers.

[0049] Accordingly, it is possible to more effectively suppress the components corresponding to at least one of (1) and (2), wherein (1) is the clock jitter between the transmitter and the receiver, wherein the transmitter is a transmitter composed of a transmission signal generating unit and a transmission unit that transmits from a transmission antenna unit, and the receiver is a receiver composed of a receiving unit that receives via a receiving antenna unit, and (2) is the timing jitter of the digital-to-analog conversion of the transmission signal or the analog-to-digital conversion of the reception signal.

[0050] An estimation device according to a third aspect of the present disclosure is based on the estimation device according to the second aspect, wherein the direct wave component is an average value of one element included in the first complex transfer function and the two or more elements.

[0051] The estimation device involved in the fourth embodiment of the present disclosure is based on the estimation device involved in the second embodiment, and the direct wave component is a direct wave transfer function, which is a function of the channel component of the direct wave calculated by multiplying the eigenvector in the pairing of eigenvalues and eigenvectors in which the eigenvalue becomes the largest by the first complex transfer function, and the eigenvalue and the eigenvector are calculated by performing eigenvalue decomposition on the correlation matrix of an element included in the first complex transfer function and the two or more elements.

[0052] The estimation device involved in the fifth embodiment of the present disclosure is based on the estimation device involved in any one of the first to fourth embodiments, and the estimation device further includes a third complex transfer function calculation unit. The third complex transfer function calculation unit calculates a third complex transfer function that corrects the frequency phase errors in the multiple subcarriers based on the distance between the transmitting antenna element and the receiving antenna element and the first complex transfer function.

[0053] The estimation device involved in the sixth embodiment of the present disclosure is based on the estimation device involved in any one of the first to fourth embodiments, and the estimation device further includes a third complex transfer function calculation unit. The third complex transfer function calculation unit calculates a third complex transfer function that corrects the frequency phase errors in the multiple subcarriers based on the distance between the transmitting antenna element and the receiving antenna element and a reference complex transfer function matrix that is a complex transfer function observed for the second period.

[0054] The estimation device involved in the seventh embodiment of the present invention is based on the estimation device involved in the fifth embodiment or the sixth embodiment, and the estimation device further includes: a biological body correlation matrix calculation unit, which records the calculated multiple third complex transfer functions in the order of observation, that is, a time series, and calculates the biological body correlation matrix by extracting the components related to the biological body in the third complex transfer functions; and a distance measuring unit, which uses the biological body correlation matrix to estimate a third distance which is the sum of a first distance and a second distance, wherein the first distance is the distance between the transmitting antenna unit and the biological body, and the second distance is the distance between the receiving antenna unit and the biological body.

[0055] Therefore, the third distance can be calculated with higher accuracy.

[0056] The estimation device involved in the eighth embodiment of the present invention is based on the estimation device involved in the seventh embodiment, and the organism correlation matrix calculation unit performs the following calculations: calculates the correlation matrix of the third complex transfer function, calculates the first vector that vectorizes the lower triangular matrix of the correlation matrix except for the elements on the diagonal line, and calculates the organism correlation matrix by extracting the components related to the organism in the first vector.

[0057] Therefore, the third distance can be calculated with higher accuracy.

[0058] The estimation device according to a ninth aspect of the present disclosure is based on the estimation device according to the seventh aspect or the eighth aspect, wherein the distance measuring unit estimates the third distance using any one of a MUSIC algorithm, a beamforming algorithm, and a Capon algorithm, where MUSIC stands for Multiple Signal Classification.

[0059] The estimation device involved in the tenth embodiment of the present disclosure is based on the estimation device involved in any one of the seventh to ninth embodiments, and at least one of the M transmitting antenna elements and the N receiving antenna elements includes 2 antenna elements. The estimation device has a position estimation unit, which takes the positions of the M transmitting antenna elements and the N receiving antenna elements as foci, calculates an ellipse whose major axis length is the third distance, and estimates the intersection of the ellipses as the position of the biological body.

[0060] Therefore, the position of the living body can be estimated with higher accuracy based on the estimation device.

[0061] In the estimation method involved in the eleventh embodiment of the present disclosure, a multi-carrier signal modulated with a plurality of sub-carrier signals is generated, the multi-carrier signal is processed and output to a transmitting antenna unit having M transmitting antenna elements, so that the multi-carrier signal is transmitted by the transmitting antenna unit, where M is a natural number greater than or equal to 1, and a received signal is observed for a first period, the received signal being a received signal received by each of the N receiving antenna elements constituting the receiving antenna unit, and the received signal being a received signal including a reflected signal resulting from the multi-carrier signal transmitted from each of the M transmitting antenna elements being reflected or scattered by a living body, the first period being a period corresponding to a period of activity originating from the living body, where N is a natural number greater than or equal to 1, but M is greater than or equal to 1. and N is a natural number greater than 2, using the multiple received signals observed in the first period, for each combination of the M transmitting antenna elements and each of the N receiving antenna elements, that is, each group of M×N combinations, for each of the multiple subcarriers corresponding to the multiple subcarrier signals, multiple first complex transfer functions representing the propagation characteristics between the transmitting antenna element and the receiving antenna element in the combination are calculated, and a second complex transfer function is calculated by dividing all elements of the first complex transfer function by a direct wave component, wherein the direct wave component is extracted using one or more elements of the first complex transfer function and is a component of the multiple received signals that does not pass through the biological body.

[0062] Based on this, a second complex transfer function can be calculated that suppresses the frequency phase error and the component corresponding to at least one of (1) and (2), wherein (1) is the clock jitter between a transmitter and a receiver, wherein the transmitter is a transmitter composed of a transmission signal generating unit and a transmission unit that transmits from a transmission antenna unit, and the receiver is a receiver composed of a reception unit that receives via a reception antenna unit, and (2) is the timing jitter of the digital-to-analog conversion of the transmission signal or the analog-to-digital conversion of the reception signal. Therefore, it is possible to estimate information related to a living body in a short time and with high accuracy using wireless signals.

[0063] This configuration uses multi-carrier signals, such as OFDM, for transmission signals, making it possible to implement bioradar using existing communication equipment. For example, OFDM receivers are already common in mobile phones, television receivers, and wireless LAN equipment, reducing costs compared to unmodulated signals.

[0064] A program according to a twelfth aspect of the present disclosure is a program for causing a computer to execute the estimation method according to the eleventh aspect.

[0065] Furthermore, the present disclosure can be implemented not only as a device but also as an integrated circuit having the processing units included in these devices, as a method using the processing units constituting the device as steps, as a program that causes a computer to execute these steps, or as information, data, or signals indicating the program. These programs, information, data, and signals can also be distributed via recording media such as CD-ROMs or communication media such as the Internet.

[0066] The following is a detailed description of the embodiments of the present disclosure using the accompanying drawings. In addition, the embodiments to be described below are all preferred examples of the present disclosure. The numerical values, shapes, materials, constituent elements, configuration positions of constituent elements, connection methods, steps, order of steps, etc. shown in the following embodiments are all examples, and their purpose is not to limit the present disclosure. Moreover, for the constituent elements of the following embodiments that are not recorded in the independent technical solutions showing the highest concept of the present disclosure, they will be described as arbitrary constituent elements constituting a more preferred embodiment. In addition, in this specification and the accompanying drawings, constituent elements having substantially the same functional structure are given the same marks and repeated descriptions are omitted.

[0067] (Implementation 1)

[0068] Hereinafter, a method of estimating the distance to a living body as a detection target by the estimation device 100 in the embodiment will be described with reference to the drawings.

[0069] [Configuration of Estimation Device 100]

[0070] Figure 1 This is a block diagram showing an example of the configuration of the estimation device 100 in the embodiment.

[0071] Figure 1 The illustrated estimation device 100 includes a transmitting antenna unit 1000, a transmitting unit 1100, a transmission signal generating unit 1200, a receiving antenna unit 1300, a receiving unit 1400, a first complex transfer function calculating unit 1500, a second complex transfer function calculating unit 1600, a third complex transfer function calculating unit 1700, a biological correlation matrix calculating unit 1800, and a distance measuring unit 1900. The estimation device 100 estimates the location of a living body 200 using the location of the estimation device 100 as a reference. For example, the estimation device 100 estimates the distance from the estimation device 100 to the living body 200.

[0072] [Transmission Signal Generator 1200]

[0073] Transmit signal generator 1200 generates a multicarrier signal in which multiple subcarrier signals are modulated, for each of the M transmit antenna elements included in transmit antenna unit 1000. Transmit signal generator 1200 generates S subcarrier signals corresponding to S (S is a natural number greater than or equal to 2) subcarriers in different frequency bands, and multiplexes the generated S subcarrier signals to generate a multicarrier signal. In this embodiment, the example of transmit signal generator 1200 generating an OFDM signal as a multicarrier signal is used for explanation. However, as long as the multicarrier signal is obtained through multicarrier modulation, it is not limited to generating an OFDM signal in which each subcarrier is orthogonal; other multicarrier signals such as simple FDM (Frequency Division Multiplexing) signals may also be generated. Furthermore, OFDM signals are signals that utilize frequency bands efficiently, and for example, are signals in which S subcarrier signals corresponding to S subcarriers are multiplexed.

[0074] Furthermore, the signal generated by the transmission signal generating unit 1200 may be shared with the signal used for communication.

[0075] [Transmitting unit 1100]

[0076] The transmitter 1100 applies appropriate processing to the signal generated by the transmission signal generator 1200 to generate a transmission wave. The processing performed here includes, for example, up-conversion processing to convert the signal from the IF (Intermediate Frequency) band to the RF (Radio Frequency) band, and amplification processing to amplify the signal to an appropriate transmission level. Figure 1 As shown, transmitting section 1100 outputs the processed multi-carrier signal to transmitting antenna section 1000, thereby transmitting the multi-carrier signal from transmitting antenna section 1000. Thus, the multi-carrier signal is transmitted from M (M is a natural number greater than or equal to 1) transmitting antenna elements 1001 included in transmitting antenna section 1000.

[0077] [Transmitting Antenna Unit 1000]

[0078] The transmitting antenna unit 1000 includes M transmitting antenna elements 1001. In this embodiment, the transmitting antenna unit 1000 includes one transmitting antenna element 1001. As described above, the transmitting antenna element 1001 transmits the signal (transmission wave) generated by the transmitting unit 1100.

[0079] [Receiving antenna unit 1300]

[0080] The receiving antenna unit 1300 includes N (N is a natural number greater than or equal to 1) receiving antenna elements 1301. In this embodiment, the receiving antenna unit 1300 includes one receiving antenna element 1301. Figure 1 As shown, one receiving antenna element 1301 receives a signal (received signal) transmitted from one transmitting antenna element 1001 and reflected by the living body 200 .

[0081] [Receiving unit 1400]

[0082] The receiving unit 1400 observes a received signal received by the receiving antenna element 1301 and including a reflected signal resulting from the multicarrier signal transmitted from the transmitting antenna element 1001 and reflected or scattered by the living body 200, for a first period corresponding to a cycle of activity derived from the living body 200. The cycle derived from the activity of the living body is a cycle derived from the living body (living body fluctuation cycle) that is equal to or longer than half a cycle of any of the cycles of respiration, heart rate, and body movement of the living body 200.

[0083] The receiving unit 1400 converts the high-frequency signal received by the receiving antenna element 1301 into a low-frequency signal suitable for signal processing. The receiving unit 1400 then demodulates the M OFDM signals transmitted by the transmitting antenna element 1001 into S×M subcarrier signals. In this embodiment, since M=1, S subcarrier signals are demodulated. Each of the S×M subcarrier signals is represented by an IQ symbol. During at least the first period, the receiving unit 1400 outputs the S×M subcarrier signals (low-frequency signals) obtained by converting the high-frequency signals received by the N receiving antenna elements 1301 to the first complex transfer function calculation unit 1500.

[0084] Alternatively, the receiving unit 1400 may always continuously observe the reception signal received by the receiving antenna unit 1300 and may continuously or periodically transmit S×M subcarrier signals (IQ symbols) to the first complex transfer function calculation unit 1500 .

[0085] [First Complex Transfer Function Calculation Unit 1500]

[0086] First complex transfer function calculation section 1500 uses the multiple received signals observed by receiving section 1400 during the first period to calculate, for each of the M×N combinations of M transmitting antenna elements 1001 and N receiving antenna elements 1301, multiple first complex transfer functions representing the propagation characteristics between transmitting antenna element 1001 and receiving antenna element 1301 in each of the multiple subcarrier signals corresponding to each of the multiple subcarriers. In this embodiment, since estimation apparatus 100 includes one transmitting antenna element 1001 and one receiving antenna element 1301, the combination is considered to be one.

[0087] In this embodiment, as shown in Equation 1, first complex transfer function calculator 1500 uses the S subcarrier signals (IQ symbols) transmitted from receiver 1400 to calculate a first complex transfer function vector h for each of the S subcarrier signals. This vector serves as a first complex transfer function representing the propagation characteristics between transmit antenna element 1001 and receive antenna element 1301.

[0088] [Mathematical formula 1]

[0089] h=[h1…,h S ] (Formula 1)

[0090] [Second Complex Transfer Function Calculation Unit 1600]

[0091] Here, the first complex transfer function vector h includes frequency fluctuation components originating from the transmitter and receiver, as well as Doppler shifts originating from the living body. Furthermore, the first complex transfer function vector h also includes reflected waves that do not pass through the living body 200, such as direct waves and reflected waves from fixed objects.

[0092] Frequency variation components originating from the transmitter and receiver include, for example: (i) attenuation or phase rotation due to spatial propagation of the transmitted signal; (ii) clock frequency deviation (f) between the transmitter and receiver. RX -f TX ); and (iii) sampling clock frequency deviation used in the wireless device for DA conversion, etc. In order to remove the phase rotation of the frequency variation components originating from the transmitter and the receiver from the first complex transfer function vector h, the second complex transfer function calculation unit 1600 extracts an arbitrary element h of the first complex transfer function vector h. l , to be used as the direct wave component.

[0093] [Mathematical formula 2]

[0094] h'=h / h l (Formula 2)

[0095] Therefore, the second complex transfer function calculation unit 1600 is as shown in Equation 2, with one element h extracted as the direct wave component. l By dividing all elements of the first complex transfer function vector h, a second complex transfer function vector h' is calculated based on this. Here, any element of the direct wave component can be used, as long as it is an element in the first complex transfer function vector h, such as element h1. The second complex transfer function vector h' is an example of a second complex transfer function.

[0096] Thus, the second complex transfer function calculation unit 1600 calculates a second complex transfer function vector h' based on the first complex transfer function vector h by performing a predetermined operation using one or more elements of the first complex transfer function vector h, thereby suppressing components corresponding to at least one of the following (1) and (2): (1) clock jitter between a transmitter and a receiver, wherein the transmitter is composed of a transmission signal generation unit 1200 and a transmission unit 1100, and transmits via a transmission antenna unit 1000, and the receiver is composed of a reception unit 1400, and receives via a reception antenna unit 1300; (2) timing jitter of digital-to-analog conversion of a transmission signal or analog-to-digital conversion of a reception signal. Specifically, the second complex transfer function calculation unit 1600 calculates the second complex transfer function by dividing all elements of the first complex transfer function by direct wave components extracted using one or more elements of the first complex transfer function. The direct wave components are components extracted from a plurality of received signals that do not pass through the biological body 200.

[0097] [Third Complex Transfer Function Calculation Unit 1700]

[0098] The third complex transfer function calculation unit 1700 obtains the second complex transfer function vector h′ calculated by the second complex transfer function calculation unit 1600 to obtain a frequency phase correction value h for correcting (calibrating) the phase error in the frequency direction. cal1 The phase error in the frequency direction is the phase error between multiple signals with different frequencies. Figure 2 The phase error required for correction will be described. Figure 2 This is a schematic diagram showing how the phase of a received signal changes depending on frequency and distance.

[0099] When signals of different frequencies propagate through space and are received, the amount of phase rotation of the transmitted signal relative to the received signal varies depending on the frequency and the distance between the transmitting antenna and the receiving antenna (hereinafter referred to as the inter-antenna distance). Figure 2The three transmitted waves 2001-A, 2001-B, and 2001-C are signals of different frequencies transmitted from the transmitting antenna unit 1000 with the same phase. It can be seen that the phases become different as the propagation distance increases (2002-B, 2002-C). Therefore, the distance between antennas can be measured by transmitting and receiving signals of multiple known frequencies to measure the phase difference, and thus can be obtained through inverse calculation. However, the phase difference actually measured includes not only the error caused by the influence of spatial propagation between the transmitting antenna and the receiving antenna, but also the error caused by the influence of the internal circuit of the transmitter or receiver or the phase characteristics of the antenna (hereinafter referred to as phase error). Therefore, in order to accurately measure the distance between antennas, it is necessary to remove the phase error from the observed signal.

[0100] Figure 3 The correspondence between the above-mentioned phase error and the channel (complex transfer function) is shown.

[0101] The phase error can be calculated by calculating the channel h represented by the matrix obtained by measurement meas The ideal channel h in space represented by the matrix that can be calculated from the distance between antennas ideal This is applicable not only to estimating the distance between antennas, but also to estimating the distance to the biological body 200.

[0102] The specific operation of the third complex transfer function calculation unit 1700 is described below. The third complex transfer function calculation unit 1700 obtains the second complex transfer function vector h' and corrects the frequency phase error. Here, the frequency phase error refers to the error that does not depend on the spatial propagation between antennas in the difference from the phase of the reference subcarrier signal S0 in the second complex transfer function matrix. Specifically, the frequency phase error includes errors caused by the frequency characteristics of the transmitting unit 1100 and the receiving unit 1400, the electrical length of the internal circuit of the transmitting unit 1100, the electrical length of the internal circuit of the receiving unit 1400, etc. The phase error includes the phase error e caused by the transmitting antenna unit 1000 and the transmitting unit 1100. jΦtx , and the phase error e caused by the receiving antenna unit 1300 and the receiving unit 1400 jΦrx .

[0103] The third complex transfer function calculation unit 1700 calculates the frequency phase correction value for each element of the second complex transfer function vector using a predetermined method. First, the third complex transfer function calculation unit 1700 calculates h, which is an ideal channel between the antenna elements, based on the previously input distance d between the transmitting antenna element 1001 and the receiving antenna element 1301. ideal Here, h idealis a complex number vector having S elements, the number of subcarriers, and the i-th element is calculated using Formula 3.

[0104] [Mathematical formula 3]

[0105] h ideal(i) =exp(-jk i d) (Formula 3)

[0106] In this k i is the wave number of the i-th subcarrier.

[0107] In this way, h ideal1 is an ideal complex transfer function between the transmitting antenna element and the receiving antenna element obtained based on the inter-antenna distance between the transmitting antenna element 1001 and the receiving antenna element 1301.

[0108] Next, the third complex transfer function calculator 1700 obtains the reference complex transfer function vector, which is the complex transfer function vector received during the second reference period from the second complex transfer function calculator 1600. The second period corresponds to the period of activity originating from the living body 200. The period of activity originating from the living body is a period originating from the living body (a biological fluctuation period) that lasts for at least half a period of any of the periods of respiration, heart rate, and body movement of the living body 200. While measurement of the reference complex transfer function vector is preferably performed in an unmanned state with minimal influence from the living body, influence from the living body or other movable objects may exist. The reference complex transfer function vector can be the initial complex transfer function vector obtained from the second complex transfer function calculator 1600. Alternatively, if the second period is not unmanned or the direct wave component is not significant, the reference complex transfer function vector can be obtained by Fourier transforming the observed complex transfer function vector for the observation time (slow time) and extracting only the components without temporal fluctuation. Furthermore, third complex transfer function calculation unit 1700 may calculate a new reference complex transfer function matrix based on timing data with minimal variation obtained by simultaneously calculating temporal variation of the absolute value of the complex transfer function, and update the reference complex transfer function matrix using the calculated new reference complex transfer function matrix. In this embodiment, since there is one transmitting antenna element 1001 and one receiving antenna element 1301, the reference complex transfer function vector is a vector having S elements.

[0109] Next, the third complex transfer function calculation unit 1700 calculates the ideal channel h ideal1 and the reference complex transfer function (channel h meas ), to calculate the frequency phase correction value h for correcting the frequency phase error in the S subcarriers cal1Specifically, the third complex transfer function calculation unit 1700 calculates the ideal channel h obtained by calculation. ideal1 , and the measured reference complex transfer function matrix h meas The ratio is used as the frequency phase correction value h cal1 Specifically, the frequency phase correction value h is calculated using the following formula 4: cal1 .

[0110] [Formula 4]

[0111]

[0112] In this Indicates the element-wise division of each vector, namely Hadamard division.

[0113] If the reference complex transfer function remains unchanged, the frequency phase correction value h cal Therefore, the third complex transfer function calculation unit 1700 can calculate the frequency phase correction value h cal1 Store it in the memory, etc., and you can use the frequency phase correction value h stored in the memory from next time. cal1 That is, once the third complex transfer function calculation unit 1700 calculates the frequency phase correction value h cal1 From next time on, you don’t need to calculate the frequency phase correction value h cal1 .

[0114] Finally, the third complex transfer function calculation unit 1700 calculates the frequency phase correction value h cal , the second complex transfer function vector h' is corrected according to Formula 5, thereby calculating the third complex transfer function vector h". The third complex transfer function vector h" is an example of the third complex transfer function.

[0115] [Formula 5]

[0116]

[0117] Here, ∠h cal Indicates h cal The ○ represents the product of each element, namely the Hadamard product.

[0118] In this manner, third complex transfer function calculator 1700 calculates a third complex transfer function vector h" that corrects the frequency phase errors in a plurality of subcarriers based on the distance between transmitting antenna element 1001 and receiving antenna element 1301 and the complex transfer function observed during the second period, i.e., the reference complex transfer function matrix.

[0119] The third complex transfer function calculation unit 1700 outputs the corrected third complex transfer function vector h″ obtained in the above manner to the subsequent biological correlation matrix calculation unit 1800.

[0120] In this embodiment, a method for calculating a correction value based on the measurement results of a complex transfer function has been described. However, if the correction value does not change over time, a value measured at a factory, for example, using a measuring instrument such as a network analyzer, may be stored in a memory as the correction value, and this correction value may be used to calculate the third complex transfer function vector h″.

[0121] [Biological Correlation Matrix Calculation Unit 1800]

[0122] The biological correlation matrix calculation unit 1800 records the calculated third complex transfer function vector h" in the order of observation, that is, the order of time series, for each of the S subcarriers and for each group of M×N combinations. Therefore, the biological correlation matrix calculation unit 1800 extracts the components related to the biological body from the third complex transfer function vector h" observed in the first period recorded in sequence in time series for each of the S subcarriers and for each group of M×N combinations, thereby calculating the biological component transfer function vector represented by an M×N dimension matrix for each of the S subcarriers.

[0123] Here, the biocomponent transfer function vector is obtained by extracting the reflected or scattered waves (biocomponents) from the received signal that have passed through the biological body 200. Methods for obtaining the biocomponent transfer function from the complex variable transfer function of the biocomponent recorded in time series include the Fourier transform disclosed in Patent Document 1 and the method using differential information disclosed in Patent Document 2.

[0124] For example, in the method using Fourier transform, the third complex variable transfer function vector h" is Fourier transformed for the observation time (slow time), and only specific frequency components are extracted, thereby calculating the biological component transfer function vector h" fft Here, the biological component transfer function vector h fft The calculated biological component transfer function vector h is calculated for each of the multiple frequency components, for example, 0.1 Hz to 3 Hz, which may be affected by the activity of the biological body. fft Further inverse Fourier transform is performed to obtain the biological component transfer function vector h in the time domain. ifft , thereby calculating the time from when the signal including the biological component is sent from the transmitting unit 1100 to when it is received by the receiving unit 1400.

[0125] Here, the biological component transfer function vector h" fftThe relationship between the frequency (column direction of the matrix) and the phase is given by Figure 4 The solid line 4100 shows how the phase of each component of the biological component transfer function vector changes with the carrier frequency when the biological body 200 is present at a certain position. The phase here is relative to the channel h that serves as the reference when calculating the second complex transfer function. l (frequency of subcarrier S0). When the biological subject 200 approaches the transmitting antenna element 1001 or the receiving antenna element 1301 from the above position, the path length of the radio wave reflected from the biological subject 200 becomes shorter, so the slope of the curve becomes flat as shown by the dotted line 4200. In principle, the slope of this curve can be used to estimate the ToF (Time of Flight) or the distance to the biological subject. Specifically, when the biological component transfer function vector h" fft Further inverse Fourier transform is performed into the subcarrier direction to obtain the time domain biological component transfer function vector h" ifft When , the time from when the signal including the biological component is sent from the transmitter to when it is received by the receiver is calculated.

[0126] Figure 5 The time domain biological component transfer function vector h" is shown ifft The relationship between time (column direction of the matrix) and phase. Figure 4 The phase changes of the solid line 4100 and the dotted line 4200 in FIG. 5 are represented by peaks shown by the solid line 5100 and the dotted line 5200, respectively. Here, the bandwidth B of the used subcarrier is expressed as Equation 6 using the time resolution Δt for obtaining the time.

[0127] [Formula 6]

[0128]

[0129] For example, when the bandwidth is 20 MHz, the time resolution is equivalent to 0.05 μs, which is equivalent to a distance resolution of about 15 m, which is insufficient for practical applications.

[0130] Therefore, in this embodiment, the MUSIC (Multiple Signal Classification) algorithm is used to achieve improved resolution. To use the MUSIC algorithm, the biological correlation matrix calculation unit 1800 calculates the biological component transfer function vector h according to the following equation 7. fft The correlation matrix R f (Organism Correlation Matrix).

[0131] [Formula 7]

[0132]

[0133] Here, the biological component transfer function vector h" fft It exists for each frequency that may include vibration caused by the biological body after Fourier transform with respect to the third complex transfer function vector h". E[·] in Formula 7 represents averaging processing in the frequency direction.

[0134] [Distance measuring unit 1900]

[0135] The distance measuring unit 1900 uses the correlation matrix R calculated by the biological correlation matrix calculation unit 1800 f The distance measurement is performed by the MUSIC algorithm. First, the distance measurement unit 1900 calculates the correlation matrix R f Perform eigenvalue decomposition to find the vector U corresponding to the signal S And the eigenvector U corresponding to the noise N Here, the eigenvectors corresponding to the signal are vectors starting from the first eigenvector and ending at the number of objects whose distance is to be measured. For example, if the object is only one person, there is only the first eigenvector. Furthermore, when the objects are k people (k is a natural number greater than 2), the eigenvectors corresponding to the signal are k eigenvectors from the first eigenvector to the kth eigenvector. Furthermore, the eigenvectors corresponding to noise are eigenvectors other than the eigenvectors corresponding to the signal.

[0136] Using the eigenvectors obtained above, the MUSIC spectrum P is calculated according to the following formula: MUSIC (d).

[0137] [Formula 8]

[0138]

[0139] Here, a(d) represents a steering vector, which is calculated according to Formula 9.

[0140] [Formula 9]

[0141]

[0142] Here, λ i represents the wavelength of the i-th subcarrier.

[0143] Take the MUSIC spectrum P obtained above MUSIC The maximum value d of (d) is the same as that described later. Figure 6The sum (third distance) of distance a (first distance) and distance b (second distance) in [ 1 ] corresponds to [ 2 ]. Distance a (first distance) is the distance between the transmitting antenna element 1001 and the living body 200. Distance b (second distance) is the distance between the receiving antenna element 1301 and the living body 200. That is, the ranging unit 1900 can calculate the third distance by calculating the maximum value d. In this way, the ranging unit 1900 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 and the second distance between the transmitting antenna unit 1000 and the living body 200.

[0144] Figure 6 This is a schematic diagram showing the positional relationship among a living body, a transmitting antenna element, and a receiving antenna element, and the position of the living body defined by a third distance.

[0145] like Figure 6 As shown, by estimating the third distance, it can be known that the position of the biological body 200 on the plane is limited to the circumference of the ellipse 6100 with the positions of the transmitting antenna unit 1000 and the receiving antenna unit 1300 as the focus. Figure 7 As shown, three or more transmitting antenna units 1000 or receiving antenna units 1300 may be used to estimate a plurality of third distances, thereby estimating the position of the biological body 200 from the intersection of the ellipses.

[0146] Figure 7 This is a schematic diagram showing how the position of a living organism is estimated by using multiple receiving antenna elements.

[0147] In this case, the receiving antenna unit 1300 of the estimation device 100 includes three receiving antenna elements 1301-1, 1301-2, and 1301-3. Furthermore, the receiving antenna unit 1300 is not limited to having three receiving antenna elements, as long as it includes three or more receiving antenna elements. Furthermore, instead of having three or more receiving antenna elements in the receiving antenna unit 1300, the transmitting antenna unit 1000 may also include three or more transmitting antenna elements.

[0148] Accordingly, for each of the three combinations (i.e., M×N combinations) of the transmitting antenna element 1001 and the receiving antenna element 1301-1, the transmitting antenna element 1001 and the receiving antenna element 1301-2, and the transmitting antenna element 1001 and the receiving antenna element 1301-3, the positions of the transmitting antenna element and the receiving antenna element included in the combination are used as the focus, and the ellipses 7100-1, 7100-2, and 7100-3 whose major axis length is the third distance are calculated. The position of the biological body 200 is estimated based on the three (i.e., M×N) intersection points closest to each other among the three (i.e., M×N) intersection points of the three ellipses 7100-1, 7100-2, and 7100-3 obtained by calculation.

[0149] [Other examples of direct wave components]

[0150] In addition, the second complex transfer function calculation unit 1600 of the embodiment converts any one element h in the first complex transfer function vector h into l As a direct wave component, the first complex transfer function vector h is divided to calculate the second complex transfer function vector h', but it is not affected by using one element h l limited.

[0151] Specifically, the extraction of the direct wave component can also use two or more elements, among the multiple elements in the first complex transfer function vector, that correspond to two or more subcarriers that are adjacent in frequency among the multiple subcarriers. The two or more elements are elements corresponding to two or more subcarriers that are all adjacent among the multiple subcarriers with different frequencies. Each of the two or more subcarriers has at least two first subcarriers that are adjacent to only one other subcarrier. Each of the subcarriers other than the two first subcarriers among the two or more subcarriers is adjacent to two other subcarriers. In this way, the two or more adjacent subcarriers include a plurality of subcarriers that are continuously adjacent, from the subcarrier corresponding to the lowest frequency to the subcarrier corresponding to the highest frequency among the two subcarriers. Hereinafter, the two or more adjacent subcarriers may be referred to as K (K = K1 + K2, K1 is an integer greater than or equal to 0 that satisfies l - K1 ≥ 1, and K2 is an integer greater than or equal to 0 that satisfies l + K2 ≤ S) subcarriers that are adjacent in the subcarrier direction.

[0152] For example, the lth element h of the first complex transfer function vector h l The direct wave component used in the division operation can be the lth element h of the first complex transfer function vector h l The average value of the K elements adjacent to the subcarrier direction. The average value of the lth element h lmean The lth element h of the second complex transfer function vector h' is calculated using the following formula 10:l ' is the average value h of the lth element calculated lmean And calculated by formula 11.

[0153] [Formula 10]

[0154]

[0155] [Formula 11]

[0156] h' l =h l / h lmean (Equation 11)

[0157] In this case, the second complex transfer function vector h' is calculated based on each element of the first complex transfer function vector h using Equation 11. The number of elements of the second complex transfer function vector h' that can be calculated using Equation 10 is SK. In this case, the steering vector a(d) used in Equation 8 is calculated as shown in Equation 12.

[0158] [Mathematical formula 12]

[0159]

[0160] Furthermore, for example, the direct wave component used in the division operation can be calculated by observing the complex transfer function over a certain period to obtain h(t), performing eigenvalue decomposition on the correlation matrix over the entire observation time, and then calculating it based on the eigenvalues and eigenvectors calculated using Equations 13 and 14. Based on this, the second complex transfer function vector h' can be calculated as shown in Equation 15.

[0161] [Mathematical formula 13]

[0162] R R =UD R U H (Equation 13)

[0163] [Mathematical formula 14]

[0164] R T =VD T V H (Equation 14)

[0165] [Mathematical formula 15]

[0166] h'(t)=h(t) / (u1 H h(t)v1) (Equation 15)

[0167] As shown in Equation 13 and Equation 14, the second complex transfer function calculation unit 1600 calculates the correlation matrix R of the first complex transfer function vector h(t): R 、RT , and the calculated correlation matrix R R 、R T Perform eigenvalue decomposition respectively and calculate the eigenvalue D based on this R 、D T And eigenvectors U and V. Next, the second complex transfer function calculation unit 1600 uses the results calculated by equations 13 and 14, as shown in equation 15, to convert the eigenvalue D R 、D T The eigenvectors u1 and v1 in the largest pair are multiplied by the first complex transfer function vector h(t) to calculate the channel component u1 of the direct wave H h(t)v1, the channel component u1 of the direct wave H h(t)v1 is used to divide all elements of the first complex transfer function vector h, thereby calculating the second complex transfer function vector h'.

[0168] Alternatively, the direct wave component can be calculated by performing eigenvalue decomposition on the correlation matrix over the entire observation time period and based on the eigenvectors calculated using equations 13 and 14. Thus, the second complex transfer function vector h' can be calculated as shown in equation 16.

[0169] [Mathematical formula 16]

[0170]

[0171] [Other examples of organism correlation matrices]

[0172] In addition, although the biological correlation matrix calculation unit 1800 of the embodiment calculates the correlation matrix R by using the Fourier transform method, f However, the lower triangular matrix can also be used to calculate the biological correlation matrix.

[0173] The biological correlation matrix calculation unit 1800 may also calculate the correlation matrix R of the second complex transfer function vector h′ as shown in Formula 17.

[0174] [Mathematical formula 17]

[0175]

[0176] The biological correlation matrix calculation unit 1800 vectorizes the lower triangular matrix of the correlation matrix R excluding the diagonal elements as shown in Formula 18 to calculate the lower triangular vector h".

[0177] [Mathematical formula 18]

[0178]

[0179] The biological correlation matrix calculation unit 1800 performs Fourier transform on the lower triangular vector h" for the observation time (slow time) and extracts only specific frequency components, thereby being able to calculate the biological component transfer function vector h" for each frequency component from about 0.1 Hz to 3 Hz. fft The biological correlation matrix calculation unit 1800 is based on the biological component transfer function vector h" fft The correlation matrix R is calculated by formula 7 f .

[0180] In this case, the steering vector a(d) in Equation 8 is calculated as follows.

[0181] [Mathematical formula 19]

[0182]

[0183] [Mathematical formula 20]

[0184]

[0185] The biological correlation matrix calculation unit 1800 calculates the correlation matrix R a The lower triangular matrix of (d) excluding the diagonal elements is vectorized as shown in Formula 21 to calculate the steering vector a(d).

[0186] [Mathematical formula 21]

[0187] a(d)=[a2(d)'a1(d)' H ,…a S (d)'a1(d)' H ,…,a S (d)'a S-1 (d)' H ] T (Equation 21)

[0188] Furthermore, when using Expression 11 and Expression 12, the biological correlation matrix calculation unit 1800 calculates (Expression 18) and (Expression 21) according to the number of elements.

[0189] [Operation of Estimation Device 100]

[0190] The operation of the estimation process performed by the estimation device 100 having the above-described configuration will be described. Figure 8 1 is a flowchart showing the estimation process of the estimation device 100 in this embodiment.

[0191] First, the estimation apparatus 100 calculates a second complex transfer function by dividing the first complex transfer function by the direct wave component ( S1100 ).

[0192] Next, the estimation apparatus 100 calculates a third complex transfer function based on the calculated frequency phase correction value ( S1200 ).

[0193] Therefore, the estimation device 100 calculates the biological correlation matrix based on the third complex transfer function, and estimates the third distance which is the sum of the distance a (first distance) between the transmitting antenna unit 1000 and the biological body 200 and the distance b (second distance) between the receiving antenna unit 1300 and the biological body 200 (S1300).

[0194] Figure 9 3 is a flowchart showing the detailed processing of calculating the second complex transfer function in step S1100 .

[0195] First, estimation apparatus 100 transmits a multicarrier signal including S subcarriers from transmitting antenna element 1001 ( S1110 ).

[0196] Then, the estimation device 100 observes the signal (received signal) transmitted from the transmitting antenna element 1001 using the receiving antenna element 1301 during the second period when the living body or other movable body is not present in the predetermined space serving as the estimation target area ( S1120 ).

[0197] Next, the estimation apparatus 100 performs multi-carrier demodulation on the received signal observed in the second period, thereby demodulating it into S subcarrier signals ( S1130 ).

[0198] Next, based on the S subcarrier signals observed during the second period, estimation apparatus 100 calculates a plurality of first complex transfer functions representing the propagation characteristics between transmitting antenna element 1001 and receiving antenna element 1301 for each of the plurality of subcarriers corresponding to the plurality of subcarrier signals (S1140). This processing is performed in parallel or sequentially for each subcarrier. Since the details are the same as above, they are omitted here. The same applies to the following.

[0199] Next, the estimation apparatus 100 calculates the direct wave component h based on the complex transfer function of each subcarrier. l (S1150).

[0200] Then, the estimation device 100 calculates the direct wave component h l and the difference h' between the complex transfer function for the second period (S1160).

[0201] Figure 10 3 is a flowchart showing the detailed process of calculating the third complex transfer function in step S1200 .

[0202] First, the estimation device 100 calculates the ideal channel h based on the predetermined distance between the transmitting antenna element 1001 and the receiving antenna element 1301. ideal (S1210).

[0203] Therefore, the estimation apparatus 100 is based on the ideal channel h ideal and the second complex transfer function vector h' to calculate the frequency phase correction value h cal (S1220).

[0204] Figure 11 3 is a flowchart showing the detailed processing of distance measurement in step S1300 .

[0205] First, estimation apparatus 100 transmits a multicarrier signal including S subcarriers from transmitting antenna element 1001 ( S1310 ).

[0206] Then, the estimation apparatus 100 observes the received signal including the reflected signal reflected by the living body 200 during the first period corresponding to the cycle of the activity of the living body 200 ( S1320 ).

[0207] Next, the estimation apparatus 100 performs multi-carrier demodulation on the received signal observed in the first period, thereby demodulating it into S signal sequences ( S1330 ).

[0208] Next, estimation apparatus 100 calculates a plurality of first complex transfer functions representing propagation characteristics between transmitting antenna element 1001 and receiving antenna element 1301 for each of the plurality of subcarriers corresponding to the plurality of subcarrier signals based on the S subcarrier signals observed in the first period ( S1340 ).

[0209] Next, the estimation apparatus 100 calculates the second complex transfer function vector h′ according to Equation 2 ( S1350 ).

[0210] Next, the estimation apparatus 100 uses the frequency phase correction value h cal , the second complex transfer function vector h′ is corrected according to Formula 5, thereby calculating the third complex transfer function vector h”(S1360).

[0211] Next, the estimation apparatus 100 calculates the biological component transfer function vector h″ based on the corrected third complex variable transfer function vector h″ fft , calculate the correlation matrix R according to formula 5 f (S1370).

[0212] Next, the estimation device 100 calculates the MUSIC spectrum P according to Equation 8. MUSIC (d)(S1380).

[0213] Finally, the estimation device 100 searches the MUSIC spectrum P MUSIC (d) When d becomes the maximum, the search result is output as the sum of the distance a between the transmitting antenna element 1001 and the living body 200 and the distance b between the living body 200 and the receiving antenna element 1301 (S1390).

[0214] [Effects, etc.]

[0215] According to the estimation device 100 and the estimation method of this embodiment, a multi-carrier signal such as OFDM is used in the transmission signal, so that the distance between the living body and the antenna can be estimated by using an existing multi-carrier transceiver.

[0216] Furthermore, by adopting the MUSIC algorithm, distance measurement with fine distance resolution is possible.

[0217] Furthermore, the estimation device 100 according to this embodiment estimates a plurality of third distances to the receiver using three or more transmitters, thereby being able to estimate the position of the living body based on the intersection of the ellipses.

[0218] Furthermore, the estimation device 100 according to this embodiment estimates a plurality of third distances to the transmitter using three or more receivers, thereby being able to estimate the position of the living body based on the intersection of the ellipses.

[0219] Furthermore, the estimation device 100 according to this embodiment can estimate the distance between a living body and an antenna or the position of a living body even in a MISO (Multiple-Input Single-output) or SIMO (Single-Input Multiple-output) or MIMO (Multiple-Input Multiple-output) configuration.

[0220] As described above, the estimation device 100 according to this embodiment can realize an estimation device and an estimation method capable of estimating the distance or position of a living body in a short time and with high accuracy using wireless signals.

[0221] The above description of the positioning sensor and distance estimation method according to one embodiment of the present disclosure is based on the embodiments. However, the present disclosure is not limited to these embodiments. Without departing from the scope of the present disclosure, various modifications that can be imagined by those skilled in the art are implemented in the present embodiment, or forms constructed by combining components from different embodiments are all included within the scope of the present disclosure.

[0222] For example, in the above embodiment, although distance estimation or position estimation of a living body 200 is described as an example, the present invention is not limited to the living body 200. When a high-frequency signal is irradiated, it is applicable to various movable bodies (such as machines) whose movement causes a Doppler effect on reflected waves.

[0223] Furthermore, for example, in the above embodiment, the example in which the number of M transmitting antenna elements is one and the number of N receiving antenna elements is one is mainly used for description, but the present invention is not limited to this. The number of M transmitting antenna elements may be two or more, and the number of N receiving antenna elements may be two or more. Alternatively, the number of M transmitting antenna elements may be two or more, and the number of N receiving antenna elements may also be two or more.

[0224] Furthermore, for example, in the above-described embodiment, the estimation device 100 includes the third complex transfer function calculation unit 1700, the biometric correlation matrix calculation unit 1800, and the distance measurement unit 1900. However, these components do not necessarily need to be included. The estimation device 100 can estimate information related to the biometric subject 200 by using the second complex transfer function vector h' calculated by the second complex transfer function calculation unit 1600. As described above, information related to the biometric subject 200 includes, for example, the distance from the estimation device to the biometric subject, the direction from the estimation device toward the biometric subject, the biometric subject's position, and the biometric subject's identifier. Thus, the second complex transfer function vector h' calculated by the estimation device 100 can be used not only to estimate the distance from the estimation device to the biometric subject, but also to estimate the direction from the estimation device toward the biometric subject, the biometric subject's position, and the biometric subject's identifier. The second complex transfer function vector h' suppresses frequency phase errors and components corresponding to at least one of (1) and (2), wherein (1) is clock jitter between a transmitter and a receiver, wherein the transmitter is a transmitter composed of a transmission signal generating unit 1200 and a transmission unit 1100 that transmits from a transmission antenna unit 1000, and the receiver is a receiver composed of a reception unit 1400 that receives via a reception antenna unit 1300, and (2) is timing jitter in digital-to-analog conversion of the transmission signal or analog-to-digital conversion of the reception signal. Therefore, it is possible to estimate the direction from the estimation device toward the living body, the position of the living body, an identifier of the living body, and the like with high accuracy.

[0225] In addition, in each of the above embodiments, each component may be formed by dedicated hardware or implemented by executing a software program suitable for each component. Each component may also be implemented by a program execution unit such as a CPU or a processor reading and executing a software program recorded on a recording medium such as a hard disk or a semiconductor memory.

[0226] Furthermore, the present disclosure can be implemented not only as a positioning sensor having these characteristic components, but also as an estimation method, etc., that uses the characteristic components included in the positioning sensor as steps. Furthermore, it can be implemented as a computer program that causes a computer to execute the characteristic steps included in the above-described method. It goes without saying that such a computer program can be distributed via a computer-readable, non-transitory recording medium such as a CD-ROM or a communication network such as the Internet.

[0227] Industrial applicability

[0228] The present disclosure can be used in positioning sensors and distance estimation methods that use wireless signals to estimate the distance or position of a biological body, and in particular can be used in measuring instruments that measure the distance or position of a biological body and a biological body including a machine, household appliances that are controlled according to the distance or position of a biological body, monitoring devices that detect intrusion into a biological body, etc.

[0229] Description of Reference Numerals

[0230] 100 Estimation Device

[0231] 200 organisms

[0232] 1000 Transmitting Antenna Unit

[0233] 1001 Transmitting Antenna Element

[0234] 1100 Sending Department

[0235] 1200 Transmission Signal Generation Unit

[0236] 1300, 1300-1, 1300-2, 1300-3 Receiving antenna

[0237] 1301 Receiving Antenna Element

[0238] 1400 Receiving Department

[0239] 1500 First complex transfer function calculation unit

[0240] 1600 Second complex transfer function calculation unit

[0241] 1700 The third complex transfer function calculation unit

[0242] 1800 Biological Correlation Matrix Calculation Department

[0243] 1900 Distance Measurement Department

[0244] 2001-A, 2001-B, 2001-C The phase of each subcarrier signal sent from the transmitting antenna unit

[0245] 2002-B, 2002-C Phase changes of signals with different frequencies sent from the transmitting antenna

[0246] 4100, 4200 Phase variation with respect to frequency of the complex transfer function matrix

[0247] 5100, 5200 Phase after inverse Fourier transform of complex transfer function matrix

[0248] 6100, 7100-1, 7100-2, 7100-3 Ellipse where the organism may exist obtained by the third distance

Claims

1. An estimation device comprising: a transmission signal generating unit for generating a multi-carrier signal by modulating a plurality of sub-carrier signals; a transmitting antenna unit having M transmitting antenna elements, where M is a natural number greater than or equal to 1; a transmitting unit configured to process the multi-carrier signal and output the processed signal to the transmitting antenna unit, thereby transmitting the multi-carrier signal via the transmitting antenna unit; a receiving antenna unit having N receiving antenna elements, where N is a natural number greater than or equal to 1; a receiving unit that observes a received signal for a first period, the received signal being a received signal received by each of the N receiving antenna elements and including a reflected signal resulting from reflection or scattering of the multicarrier signal transmitted from each of the M transmitting antenna elements by a living body, the first period being a period corresponding to a period of activity derived from the living body; a first complex transfer function calculation unit, using the plurality of received signals observed by the receiving unit during the first period, to calculate, for each of M×N combinations of each of the M transmitting antenna elements and each of the N receiving antenna elements, a plurality of first complex transfer functions representing propagation characteristics between the transmitting antenna element and the receiving antenna element in the combination, for each of the plurality of subcarriers corresponding to the plurality of subcarrier signals; as well as The second complex transfer function calculation unit calculates a second complex transfer function by dividing all elements of the first complex transfer function by direct wave components, wherein the direct wave components are extracted using one or more elements of the first complex transfer function and are components of the multiple received signals that do not pass through the biological body.

2. The estimation device according to claim 1, The one or more elements used for extracting the direct wave component include two or more elements corresponding to two or more subcarriers adjacent in frequency among the plurality of subcarriers.

3. The estimation device according to claim 2, The direct wave component is an average value of one element included in the first complex transfer function and the two or more elements.

4. The estimation device according to claim 2, The direct wave component is a direct wave transfer function, which is a function of the channel component of the direct wave calculated by multiplying the eigenvector in the pairing of eigenvalues and eigenvectors in which the eigenvalue becomes the largest by the first complex transfer function, and the eigenvalue and the eigenvector are calculated by performing eigenvalue decomposition on the correlation matrix of an element included in the first complex transfer function and the two or more elements.

5. The estimation device according to any one of claims 1 to 4, The estimation device further includes a third complex transfer function calculation unit that calculates a third complex transfer function that corrects the frequency phase errors in the plurality of subcarriers based on the distance between the transmitting antenna element and the receiving antenna element and the first complex transfer function.

6. The estimation device according to any one of claims 1 to 4, The estimation device further includes a third complex transfer function calculation unit, which calculates a third complex transfer function that corrects the frequency phase errors in the multiple subcarriers based on the distance between the transmitting antenna element and the receiving antenna element and a reference complex transfer function matrix that is a complex transfer function observed for the second period.

7. The estimation device according to claim 5 or 6, The estimation device further comprises: a biological correlation matrix calculation unit that sequentially records the calculated plurality of third complex transfer functions in the order in which they were observed, i.e., in a time series, and calculates a biological correlation matrix by extracting biologically relevant components from the third complex transfer functions; and The ranging unit estimates a third distance which is the sum of a first distance and a second distance using the biological body correlation matrix, wherein the first distance is the distance between the transmitting antenna unit and the biological body, and the second distance is the distance between the receiving antenna unit and the biological body.

8. The estimation device according to claim 7, The biological correlation matrix calculation unit performs the following calculations: Calculate the correlation matrix of the third complex transfer function, Calculate a first vector that vectorizes the lower triangular matrix of the correlation matrix excluding the diagonal elements, The organism correlation matrix is calculated by extracting the organism-related components from the first vector.

9. The estimation device according to claim 7 or 8, The distance measuring unit estimates the third distance using any one of a MUSIC algorithm, a beamforming algorithm, and a Capon algorithm, where MUSIC stands for Multiple Signal Classification.

10. The estimation device according to any one of claims 7 to 9, At least one of the M transmitting antenna elements and the N receiving antenna elements includes two antenna elements, The estimation device includes a position estimation unit that uses the positions of the M transmitting antenna elements and the N receiving antenna elements as focuses, calculates two or more ellipses whose major axis lengths are the third distance, and estimates the intersection of the ellipses as the position of the biological body.

11. An estimation method, wherein: generating a multi-carrier signal modulated with a plurality of sub-carrier signals, The multi-carrier signal is processed and output to a transmission antenna unit having M transmission antenna elements, so that the multi-carrier signal is transmitted by the transmission antenna unit, where M is a natural number greater than or equal to 1. A received signal is observed during a first period, the received signal being received by each of the N receiving antenna elements constituting the receiving antenna unit, and the received signal being a reflected signal resulting from reflection or scattering of the multicarrier signal transmitted from each of the M transmitting antenna elements by a living body, wherein the first period is a period corresponding to a period of activity originating from the living body, N being a natural number greater than or equal to 1, and at least one of M and N being a natural number greater than or equal to 2. Using the plurality of received signals observed during the first period, for each of the M×N combinations of each of the M transmitting antenna elements and each of the N receiving antenna elements, a plurality of first complex transfer functions representing propagation characteristics between the transmitting antenna element and the receiving antenna element in the combination are calculated for each of the plurality of subcarriers corresponding to the plurality of subcarrier signals. A second complex transfer function is calculated by dividing all elements of the first complex transfer function by direct wave components, wherein the direct wave components are extracted using one or more elements of the first complex transfer function and are components of the plurality of received signals that do not pass through the biological body.

12. A program for causing a computer to execute the estimation method according to claim 11.

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