Combating reflections (hence multipath) from moving objects is precisely the reason Wireless LANs use orthogonal frequency division multiplexing (implemented wi

Combating reflections (hence multipath) from moving objects is precisely the reason Wireless LANs use orthogonal frequency division multiplexing (implemented with an FFT). The environment leaves its imprint on the received signal and depending on your point of view: communications or radar, that imprint is either information to be retrieved (radar) or eliminated (communications). If you look at one of the early WLAN papers [1] (I'm an author), Figure 1(b) shows a frequency selective fade, meaning there is a dip, or null, in the received signal and some of the frequencies are missing. The way we created that null was by a person walking through the room. With a change of emphasis in the signal processing, a WLAN is a very good person detector. [1] http://wireless.ece.ufl.edu/twong/Preprints/00566198.pdf http://wireless.ece.ufl.edu/twong/Preprints/00566198.pdf