Estimation method, estimation device, and program

A non-transitory computer-readable recording medium for use in a computer, the recording medium having a computer program recorded thereon for estimating a number of living bodies that are present in a space and include at least one living body, using (i) a transmission unit including at least one transmission antenna element and (ii) a reception unit including N reception antenna elements where N is a natural number greater than or equal to two, the computer program causing the computer to execute:

• calculating a plurality of complex transfer functions, based on reception signals respectively received by the N reception antenna elements during a predetermined period, the plurality of complex transfer functions each representing propagation characteristics between the at least one transmission antenna element and the N reception antenna elements;
• extracting a variation component corresponding to each of the N reception antenna elements, from the plurality of complex transfer functions calculated in the calculating of the plurality of complex transfer functions, the variation component being caused by the at least one living body;
• calculating a correlation matrix based on the variation component corresponding to each of the N reception antenna elements extracted in the extracting;
• calculating eigenvalues of the correlation matrix calculated in the calculating of the correlation matrix;
• and
• estimating the number of living bodies in a predetermined method, based on a distribution of the eigenvalues calculated, wherein the distribution of the eigenvalues is ratio information which indicates ratios or differences between adjacent eigenvalues.

A computer configured to estimate a number of living bodies that are present in a space which includes at least one living body, and includes (i) a transmission unit including at least one transmission antenna element and (ii) a reception unit including N reception antenna elements where N is a natural number greater than or equal to two, the computer comprising:

• a processor configured to:
• calculate a plurality of complex transfer functions, based on reception signals respectively received by the N reception antenna elements during a predetermined period, the plurality of complex transfer functions each representing propagation characteristics between the at least one transmission antenna element and the N reception antenna elements;
• extract a variation component corresponding to each of the N reception antenna elements, from the plurality of complex transfer functions calculated, the variation component being caused by the at least one living body;
• calculate a correlation matrix based on the variation component corresponding to each of the N reception antenna elements extracted;
• calculate eigenvalues of the correlation matrix;
• and
• estimate the number of living bodies in a predetermined method, based on a distribution of the eigenvalues calculated, wherein the distribution of the eigenvalues is ratio information which indicates ratios or differences between adjacent eigenvalues.