Discovery of Blocking Terrain in a Millimeter- Wave Network by On-the-Fly Incoherent Tomography

Future mm-wave mobile communications networks will likely employ beamforming arrays. A principal difficulty in such networks is initiating and maintaining beam alignment. This problem is exacerbated by intermittent blockage along the line of sight (LOS), and is particularly acute in peer-to-peer links between mobiles operating among buildings and vehicles. In this paper we demonstrate a simple technique for unaided discovery of blocking objects in such networks. This technique uses histories of path loss accumulated “on the fly” between pairs of mobiles to construct a map indicating the likely locations and geometry of blocking objects. Information obtained using this technique can be used to improve beam pointing initialization and tracking, as well as to anticipate outages and proactively set up multi-hop links.