Tracking Moving People Through Walls Using Wi-Fi Signals

Fadel Adib and Dina Katabi of MIT have developed Wi-Vi, a new technology that can track moving people through walls and behind closed doors using Wi-Fi signals. It can determine with high accuracy up to three moving objects. The technology relies on capturing the reflections of its own transmitted signals off moving objects behind a wall in order to track them. Wi-Vi encodes its signal across multiple antennas to cancel out all static reflectors at the receive antenna. A Wi-Vi device has two transmit antennas and a single receive antenna, so a person can communicate with it using simple gestures without carrying or wearing any wireless device. The technology can detect very simple gestures made through a wall, making it the first through-wall gesture-based interface. Applications include emergency situations, personal security, and smart sensing.

Transcript

00:00:00 this video shows Wi-Vi, a device that can track  human motion behind walls and enclosed rooms.   Wi-Vi is behind the wall as indicated by the red  arrow. The blue window at the bottom shows the   output of Wi-Vi. The room is initially empty.  This is why the signal is zero. A person enters   the room. As he moves away, the device shows a  negative signal. When he moves toward the device,   it shows a positive signal. When he  stops, it outputs only the zero line,   meaning there is no motion. Even when he performs  a minor movement like now, Wi-Vi registers it.