PriSense: Privacy-Preserving Wireless Sensing for Vital Signs Monitoring

Contactless vital signs monitoring can be realized by wireless sensing techniques, where the variations of channel state information (CSI) are utilized to acquire information about a remote object. Due to the openness of wireless medium and the public structure of the pilot signals, any passive observer (eavesdropper) can sniff the signal transmission and perform channel estimation, based on which the vital signs information can be extracted. To realize privacy protection, in this letter, a pilot masking technique is proposed, where the pilot signal with crafted spectral characteristics is designed for wireless sensing such that the artificial variation patterns are introduced into the equivalent CSI obtained by the eavesdropper. Consequently, the real CSI variations are masked, which leads the eavesdropper to make an incorrect estimation. Further, a round-trip signaling method is developed to avoid secret information exchange between legitimate users. Simulation results demonstrate the superiority of the proposed method in terms of sensing accuracy and privacy-protection capability compared with existing works.