Through-Wall Multi-Subject Localization and Vital Signs Monitoring Using UWB MIMO Imaging Radar

Abstract

Radar-based non-contact vital signs monitoring has great value in through-wall detection applications. This paper presents the theoretical and experimental study of through-wall respiration and heartbeat pattern extraction from multiple subjects. To detect the vital signs of multiple subjects, we employ a low-frequency ultra-wideband (UWB) multiple-input multiple-output (MIMO) imaging radar and derive the relationship between radar images and vibrations caused by human cardiopulmonary movements. The derivation indicates that MIMO radar imaging with the stepped-frequency continuous-wave (SFCW) improves the signal-to-noise ratio (SNR) critically by the factor of radar channel number times frequency number compared with continuous-wave (CW) Doppler radars. We also apply the three-dimensional (3-D) higher-order cumulant (HOC) to locate multiple subjects and extract the phase sequence of the radar images as the vital signs signal. To monitor the cardiopulmonary activities, we further exploit the VMD algorithm with a proposed grouping criterion to adaptively separate the respiration and heartbeat patterns. A series of experiments have validated the localization and detection of multiple subjects behind a wall. The VMD algorithm is suitable for separating the weaker heartbeat pattern from the stronger respiration pattern by the grouping criterion. Moreover, the continuous monitoring of heart rate (HR) by the MIMO radar in real scenarios shows a strong consistency with the reference electrocardiogram (ECG).

Non-Contact Heart Rate Monitoring Based on Millimeter Wave Radar

“…The electromagnetic wave-based bio-radar shows advantages in non-contact, non-invasion of privacy, and strong scalability. It has been extensively studied to search for the post-disaster survivor, monitor sleep, evaluate drivers' health in vehicles, and detect vital signs through walls [8][9][10][11].…”

Localization of Dielectric Anomalies with Multi-Monostatic S11 Using 2D MUSIC Algorithm with Spatial Smoothing

“…Microwave imaging systems span a wide range of applications such as concealed weapon detection [ 1 ], medical imaging [ 2 ], through-the-wall detection [ 3 ], non-destructive testing [ 4 ], etc. In recent years, these systems have drawn significant attention owing to their lower cost and compact size.…”

Pengaruh Dinding Penghalang pada Deteksi Tanda Vital Pernapasan dengan Through Wall Radar

“…A through-wall radar (TWR) is one of the radar applications emitting electromagnetic waves that can penetrate the wall and receive reflections from certain objects behind the wall [1]. TWR is used to generate good wall penetration by working on very wide bandwidths, thus having the potential to detect small displacements, such as chest wall movement in breathing [2].…”

“…Breathing detection radar using ultra-wideband impulse radar (UWB) has also been discussed in [6], [7]. Meanwhile, in [8], breathing detection experiments with UWB MIMO imaging radar were shown. From the study, results showed that radar could detect vital signs of breathing behind walls.…”