Temporal-Spatial Equivalent Virtual Array Technique for Accurate Vital Sign Monitoring

Abstract

A novel temporal-spatial equivalent virtual array technique for accurate vital sign monitoring based on a 24GHz continuous wave (CW) radar is proposed. By leveraging the similarity between the single-input-single-output (SISO) CW radar single-channel phase signal and the single-input-multiple-output (SIMO) radar multiply-array signal, an equivalent virtual array could be synthesized, which completes the transformation from time to space. The derivation of the equivalent theory reveals that the different frequency components of human thorax surface motion can be equivalent to different direction-of-arrival (DOA) angles of waves incident on the virtual array. Subspace-based DOA estimation algorithm is employed to extract the array features and a super-resolution spectral estimation performance is achieved. A coarse-to-fine estimation method is presented for accurate heart rate and respiration rate monitoring. Experiments were carried out and the results proved that the proposed technique can accurately and stably estimate the respiration rate and heart rate of the human body with super-resolution.