Inverse Beamforming for navigating in multipath environments

Radionavigation in indoor and urban environments suffers from the effects of severe multipath and low signal strength. In this paper, we present a new technique, Inverse Beamforming, designed to reduce multipath power using signals from purpose deployed beacons. This technique complements other multipath mitigation methods which receivers use to make pseudorange measurements. Inverse beamforming is based on array signal processing by the user; however, a user needs only a single antenna, and the array itself is housed by the beacon (hence the name). Thus, a mobile user is not required to carry a cumbersome antenna array while taking full advantage of array signal processing gains. We present the concept and results of a laboratory test for this technique.