Using Wi-Fi to “see” behind closed doors is easier than anyone thought

With nothing but a smartphone and some clever computation, researchers can exploit ambient signals to track individuals in their own homes. They do this by measuring the change in the signal strength as they walk around outside the target building or room. Indeed, they have created an app that uses the smartphone’s built-in accelerometers to record this movement and then analyzes the change in signal strength as they move. In that way, it is possible to number-crunch the position of the transmitter, even in the presence of numerous reflections and distortions.

Source: Using Wi-Fi to “see” behind closed doors is easier than anyone thought – MIT Technology Review