Passive Detection of Moving and Stationary Human with Wi-Fi

Non-invasive human sensing based on radio signals has attracted numerous research interests and fostered a broad range of innovative applications of localization, gesture recognition, smart health-care, etc., for which a primary primitive is to detect human presence. Previous works have studied to detect moving humans via signal variations caused by human movements. For stationary people, however, the existing approaches often employ a prerequisite scenario-tailored calibration of channel profile in human-free environments. Based on in-depth understanding of human motion-induced signal attenuation reflected by PHY layer Channel State Information (CSI), we propose DeMan, a unified scheme for non-invasive detection of moving and stationary human on commodity Wi-Fi devices. DeMan takes advantages of both amplitude and phase information of CSI to detect moving targets. In addition, DeMan considers human breathing as an intrinsic indicator of stationary human presence and adopts sophisticated mechanisms to detect particular signal patterns caused by minute chest motions, which could be destroyed by significant whole-body motion or hidden by environmental noises. By doing this, DeMan is capable of simultaneously detecting moving and stationary people with only a small number of prior measurements for model parameter determination, yet without the cumbersome scenario-specific calibration. Extensive experimental evaluation in typical indoor environments validates the great performance of DeMan in case of various human poses and locations and diverse channel conditions. Particularly, DeMan provides a detection rate of around 95% for both moving and stationary people while identifying human-free scenarios by 96%, all of which outperform the existing methods by about 30%. (This chapter is based on our previously published paper. Ⓒ[2015] IEEE. Reprinted, with permission, from Wu et al. (Non-invasive detection of moving and stationary human with WiFi. IEEE J Sel Areas Commun 33(11):2329–2342, 2015).)