Number and Angle Analysis in UWB Radar Deployment for Vital Sign Monitoring

In recent years, more studies focus on the UltraWide Band (UWB) radar to provide a noncontact vital sign monitoring service. To further improve the accuracy of vital sign monitoring, the UWB radar network composed by multiple radars is considered for providing information on different angles. The radar deployment is a key factor in the radar network to impact the monitoring results, since that different deployments bring diverse combinations of vital sign information. To the best of our knowledge, few studies attempt to optimize the radar deployment for the purpose of improving the vital sign monitoring accuracy. This paper provides an analysis on the number and angle in radar deployment for vital sign monitoring. To firstly validate the superiority of utilizing multiple radars rather than the single radar, the theoretical analysis is performed by combining the vital sign monitoring model and the Cramer-Rao Low Bound (CRLB) theory. Then experiments for discussing the effect of the radar number and the angle between radars are conducted in realistic environment. Considering the radar number from 2 to 4, signals are acquired from radars located symmetrically with the subject sitting at the center. Additionally, the deployments of two radars with angles of 0°, 60°, 120°, 180°, 240° and 300° are discussed, ensuring that at least one radar is directed to the chest of the subject. A Neural Network (NN) based data fusion method is performed to obtain the fused vital signal from the radars. The accuracy of the NN is discussed as the evaluating indicators for these deployments.