Validation of Propagation Delay on The Development of Wi-Fi CSI Based Channel Sounder for Passive Motion Sensing

Wi-Fi channel state information (CSI) has been widely utilized in various motion sensing applications such as motion detection, recognition, localization and tracking. Comparison with Doppler frequency, propagation delay is unreliable due to a non-synchronization between two Wi-Fi stations, thus it is hardly utilized for motion sensing. Since the CSI B2B calibration in the previous work introduced a form of synchronization via a cable channel, the propagation delay has become utilizable. In this paper, a performance and reliability of the CSI propagation delay will be validated as well as addressing the source of delay offset due to B2B calibration. In addition, applicability of utilizing propagation delay in a person falling scenario will be demonstrated as one of the motion sensing application.