Estimating method and estimating device

1. An estimating method for an estimating device that includes an antenna, the antenna including M transmission antenna elements and N reception antenna elements, where M and N are each a natural number of two or more, the estimating method comprising:

transmitting transmission signals to a target region using the M transmission antenna elements;

receiving, by the N reception antenna elements, reception signals that include one or more reflection signals resulting from one or more of the transmission signals transmitted from the M transmission antenna elements being reflected by at least one living body;

calculating, from the reception signals received by the N reception antenna elements during a predetermined period, an M×N complex transfer function matrix that includes complex transfer functions as components, the complex transfer functions indicating characteristics of propagation between the M transmission antenna elements and the N reception antenna elements;

extracting, using the M×N complex transfer function matrix, K living-body component complex transfer function matrices belonging to a predetermined frequency range and corresponding to different frequencies by a predetermined method, where K is a natural number of two or more, the K living-body component complex transfer function matrices corresponding to components affected by vital activity that includes at least one of respiration, heartbeat, or motion of the at least one living body;

generating K living-body component complex transfer function vectors by rearranging each of the K living-body component complex transfer function matrices into a vector;

calculating a correlation matrix of the K living-body component complex transfer function vectors for a frequency direction;

calculating a correlation matrix vector by rearranging the correlation matrix into a vector;

calculating a steering vector constituted by components corresponding to positions of a plurality of regions that are obtained by being divided from the target region;

calculating an extended steering vector by changing a dimension of the steering vector to a dimension that is identical to a dimension of the correlation matrix vector;

estimating a living-body signal intensity vector by performing compressed sensing for an unknown value that is the living-body signal intensity vector using the correlation matrix vector and the extended steering vector, the living-body signal intensity vector being included in the correlation matrix vector, and corresponding to an intensity of a signal from the at least one living body located in at least one region among the plurality of regions; and

estimating, among a plurality of components constituting the living-body signal intensity vector, a total number of one or more components each having a value greater than or equal to a predetermined threshold to be a total number of the at least one living body, and one or more positions of one or more regions corresponding to the one or more components among the plurality of regions to be one or more estimated positions of the at least one living body.

2. The estimating method according to claim 1 , wherein

in extracting the K living-body component complex transfer function matrices, the K living-body component complex transfer function matrices corresponding to the components affected by the vital activity that includes at least one of respiration, heartbeat, or motion of the at least one living body are extracted by:

calculating absolute values of frequency responses of the M×N complex transfer function matrix, the frequency responses being included in a predetermined frequency range; and

extracting one or more of the frequency responses each having one of the absolute values that is greater than or equal to a predetermined threshold.

3. The estimating method according to claim 1 , wherein

in transmitting the transmission signals, a multi-carrier signal into which L subcarrier signals are modulated is output to each of the M transmission antenna elements, to cause the M transmission antenna elements to transmit a plurality of the multi-carrier signals as the transmission signals, where L is a natural number of two or more,

the reception signals received by the N reception antenna elements include one or more reflection signals resulting from one or more of the plurality of multi-carrier signals being reflected by the at least one living body,

the M×N complex transfer function matrix that includes, as components, the complex transfer functions indicating characteristics of propagation between the M transmission antenna elements and the N reception antenna elements is calculated for each of L subcarriers corresponding to the L subcarrier signals, from the reception signals received by the N reception antenna elements during the predetermined period, to obtain L M×N complex transfer function matrices, and

in extracting the K living-body component complex transfer function matrices, the L M×N complex transfer function matrices are used to extract the K living-body component complex transfer function matrices by the predetermined method, where K is a natural number of two or more, the K living-body component complex transfer function matrices belonging to the predetermined frequency range and corresponding to different frequencies.

4. An estimating device, comprising:

a transmission antenna that includes M transmission antenna elements, where M is a natural number of two or more;

a reception antenna that includes N reception antenna elements, where N is a natural number of two or more;

a transmitter that transmits transmission signals to a target region using the M transmission antenna elements;

a receiver that receives, using the N reception antenna elements, reception signals that include one or more reflection signals resulting from one or more of the transmission signals transmitted from the M transmission antenna elements being reflected by at least one living body;

a complex transfer function calculator that calculates, from the reception signals received by the N reception antenna elements during a predetermined period, an M×N complex transfer function matrix that includes complex transfer functions as components, the complex transfer functions indicating characteristics of propagation between the M transmission antenna elements and the N reception antenna elements;

an extractor that extracts, using the M×N complex transfer function matrix, K living-body component complex transfer function matrices belonging to a predetermined frequency range and corresponding to different frequencies by a predetermined method, where K is a natural number of two or more, the K living-body component complex transfer function matrices corresponding to components affected by vital activity that includes at least one of respiration, heartbeat, or motion of the at least one living body;

a living-body component complex transfer function vector calculator that generates K living-body component complex transfer function vectors by rearranging each of the K living-body component complex transfer function matrices into a vector;

a correlation matrix calculator that calculates a correlation matrix of the K living-body component complex transfer function vectors for a frequency direction;

a correlation matrix vector calculator that calculates a correlation matrix vector by rearranging the correlation matrix into a vector;

a steering vector calculator that calculates a steering vector constituted by components corresponding to positions of a plurality of regions that are obtained by being divided from the target region;

an extended steering vector calculator that calculates an extended steering vector by changing a dimension of the steering vector to a dimension that is identical to a dimension of the correlation matrix vector;

a compressed sensor that estimates a living-body signal intensity vector by performing compressed sensing for an unknown value that is the living-body signal intensity vector using the correlation matrix vector and the extended steering vector, the living-body signal intensity vector being included in the correlation matrix vector, and corresponding to an intensity of a signal from the at least one living body located in at least one region among the plurality of regions; and

an estimator that estimates, among a plurality of components constituting the living-body signal intensity vector, a total number of one or more components each having a value greater than or equal to a predetermined threshold to be a total number of the at least one living body, and one or more positions of one or more regions corresponding to the one or more components among the plurality of regions to be one or more estimated positions of the at least one living body.