Researchers in UC Santa Barbara have proposed a new foundation that can enable high-quality imaging of still objects with only WiFi signals. Their method uses the Geometrical Theory of Diffraction and the corresponding Keller cones to trace edges of the objects. The technique has also enabled, for the first time, imaging, or reading, the English alphabet through walls with WiFi, a task deemed too difficult for WiFi due to the complex details of the letters.
The team proposed a Keller cone-based imaging projection kernel. This kernel is implicitly a function of the edge orientations, a relationship that is then exploited to infer the existence/orientation of the edges via hypothesis testing over a small set of possible edge orientations. If existence of an edge is determined, the edge orientation that best matches the resulting Keller cone-based signature is chosen for a given point that they are interested in imaging.
More information:
https://news.ucsb.edu/2023/021198/wifi-can-read-through-walls