Low-cost WiFi-based system can see through walls

A system using low-power WiFi signals to track people's movement, even behind walls, could be used in rescue work or by the military, its U.S. developers say. Researchers at MIT's Computer Science and Artificial Intelligence Laboratory report such a system could provide the ability to spot people in different rooms using low-cost WiFi technology. Previous efforts to develop such a system have involved the use of expensive and bulky radar technology, they said. "We wanted to create a device that is low-power, portable and simple enough for anyone to use, to give people the ability to see through walls and closed doors," MIT computer scientist and electrical engineer Dina Katabi said. Dubbed "WiVi," the concept is similar to radar and sonar imaging, but emits a low-power WiFi signal and uses its reflections to track moving humans, even if they are in closed rooms or hiding behind a wall. WiVi could be used to help search-and-rescue teams to find survivors trapped in rubble after an earthquake, the researchers said, or to allow police officers to identify the number and movement of suspected criminals within a building to avoid walking into an ambush.