Device-free Wireless Monitoring System

Abstract

1. How can we bridge the object motion with the wireless signal?
  • The movement of a object embedded in the environment will casue corresponding changes in the Wireless Channel Station Information (CSI). As a result, intuitively, we can extract the object motion from the measured CSI of Wireless Links. Luckily, most of the WiFi devices support/provide CSI out put now such as Intel 5300, Marvell 88W8897
2. How do get rid of multipath distortions since it is alomost everywhere?
  • We do not have to. By using Time Reversal techniques, we can leverage the multipath components by exploring the statistical property of the received electromagnetic (EM) signals. In other words, we treat LoS and NLoS signals as a whole. Thus, multipath is not a problem at all.
3. Does the theoretical model matches with the practical environments?

Key words: Motion Sensing, CSI, Multipath, Time Reversal.