Analysis of Keller Cones for RF Imaging

Imaging still objects with the received signal power of off-the-shelf WiFi transceivers is considerably challenging. The interaction of object edges with the incoming wave, dictated by the Geometrical Theory of Diffraction and the resulting Keller cones, presents new possibilities for imaging with WiFi via edge tracing. In this paper, we are interested in bringing a comprehensive understanding to the impact of several different parameters on the Keller cones and the corresponding edge-based imaging, thereby developing a foundation for a methodical imaging system design. More specifically, we consider the impact of parameters such as curvature of a soft edge, edge orientation, distance to the receiver grid, transmitter location, and other parameters on edge-based WiFi imaging, via both analysis and extensive experimentation. We finally show that Keller cones can be used for imaging objects that lack visibly-sharp edges, as long as the curvature of the edge is small enough, by imaging a number of such daily objects.