Researchers from the laboratory of Professor Yasamin Mostofofi at UC Santa Barbara presented a new method that enables the creation of high-quality images of stationary objects using WiFi signals. This groundbreaking technique utilizes the geometric theory of diffraction and tracks the contours of objects using Keller cones. For the first time, this method has made it possible to read the English alphabet through walls using WiFi, a previously challenging task due to the intricacy of the letters.
“Generating images of stationary objects using WiFi poses a significant challenge due to the absence of movement,” said Professor Mostofor, who specializes in electrical engineering and computer engineering. To overcome this hurdle, the researchers focused on tracing the contours of objects.
The Mostofi laboratory embarked on their studies in 2009, exploring the potential applications of radio frequency signals, such as WiFi, for various purposes including crowd analytics, identification, smart health, and smart spaces.
“When a wave encounters the edge of an object, it produces a cone of outgoing rays that leave distinct traces on the receiver depending on the edge’s orientation. We have developed a mathematical model that utilizes these traces to determine the edge orientation, effectively creating a map of the scene’s contours,” explained Professor Mostofor.
Additionally, the researchers investigated the impact of various parameters, including surface curvature, region orientation, receiver distance, and transmitter location on Keller cones and their proposed image system based on edges.
During the experiments, the research team employed three standard WiFi transmitters that emitted radio waves into the designated area. WiFi receivers were installed on an unmanned vehicle, simulating a moving receiving grid.
By utilizing this model, the researchers successfully reconstructed the contours of complex shapes, including alphabetic letters, based on Wi-Fi signals. It is important to note that the team from Santa Barbara does not claim that WiFi can be used to read materials like printed pages through solid walls.
Nevertheless, this discovery holds significant practical implications. The ability to define stationary objects can prove invaluable in fields such as smart homes, structural monitoring, search and rescue operations, surveillance, and archaeological excavations.