Multi-Person Localization via RF Body Reflections

Fadel Adib, Zach Kabelac, Dina Katabi. Usenix NSDI’15, Oakland, California, May 2015


WiTrack is a device that tracks the 3D motion of a user from the radio signals reflected off her body. It works even if the person is occluded from the WiTrack device or in a different room. WiTrack does not require the user to carry any wireless device, yet its accuracy exceeds current RF localization systems, which require the user to hold a transceiver. It transmits wireless signals whose power is 100 times smaller than Wi-Fi and 1,000 times smaller than cellphone transmissions.

WiTrack localizes the center of a human body to within 10 to 13 cm in the x and y dimensions (about the size of an adult hand), and 21 cm in the z dimension. It also provides coarse tracking of body parts, identifying the direction of a pointing hand with a median of 11.2 degrees. It can also detect falls with 96.9 percent accuracy. WiTrack can be incorporated into consumer electronics and has a wide set of applications.