MTrack: Tracking Multiperson Moving Trajectories and Vital Signs With Radio Signals

In this article, we propose a human sensing system with radio signals, MTrack, for in-home healthcare, which is capable of tracking the trajectories of moving persons and vital signs of static persons under the multiperson scenarios. To achieve this, we implement a multiantenna wideband system that can provide high-resolution Angle of Arrival (AoA) and Time of Flight (ToF). A 2-D beamformer is utilized to transform the raw radio signals into the AoA-ToF domain. To track the trajectories of moving persons, we leverage the movement of persons to cancel static multipaths and propose a path selection algorithm to estimate the locations of human and suppress the interferences from dynamic multipaths. To track the vital signs of static persons, we utilize the breath of static persons to eliminate static multipaths and propose a correlation-based algorithm to eliminate dynamic multipaths. Extensive experiments show that the proposed MTrack system is capable of tracking multiple moving persons with subdecimeter level accuracy, and can estimate the breath and heartbeat rate of static persons with the median accuracy of 99.8% and 98.46%, respectively.