ABSTRACT

Wi-Vi is a new technology that enables seeing through walls using Wi-Fi signals. It allows us to

track moving humans through walls and behind closed doors. Wi-Vi relies on capturing the

reflections of its own transmitted signals off moving objects behind a wall in order to track them.

Wi-Vi's operation does not require access to any device on the other side of the wall. Wi-Fi

signals are typically information carriers between a transmitter and a receiver. Wi-Fi can also

extend our senses, enabling us to see moving objects through walls and behind closed doors,

under this technology communication is possible by combination of gestures and by messaging

without even using the any transmitter. In particular, such signals can be used to identify the

number of people in a closed room and their relative locations and also identify simple gestures

made behind a wall, and combine a sequence of gestures to communicate messages to a wireless

receiver without carrying any transmitting device. Two main innovations are being introduced:

First, it shows how one can use MIMO interference nulling to eliminate reflections off static

objects and focus the receiver on a moving target. Second, it shows how one can track a human

by treating the motion of a human body as an antenna array and tracking the resulting RF beam.

Wi-Vi could also be built into a smart phone or a special handheld device and used in

search-and-rescue missions and law enforcement. The key benefits of Wi-Vi over current ways

of seeing through walls, such as radar and sonar, are cost, power and size. At the heart of the

technology is its encoding scheme, which can be implemented in silicon. Wi-Vi could be built

into a cell phone soon, and for not much more than the cost of a regular Wi-Fi module. Bringing

wall-penetrating vision to handheld devices could open up a lot more uses for it. Current radar-

based systems used in the U.S. military are so big they need to be transported on trucks. Even the

Army might need a more portable tool for seeing through walls in certain settings. Because of its

low resolution, Wi-Vi could actually enhance people's privacy rather than erode it in some cases.