FastBeam: Practical fast beamforming for indoor environments

In this work, we explore algorithms to perform fast beamforming when relying only on RSSI measurements in indoor environments. Fast beamforming allows for a faster adaptation of the antenna weights for environments where the channel is time varying. Time varying channel can be caused by client mobility, orientation changes at the client, and environmental changes. We show that existing techniques for RSSI based beamforming have a high time complexity, and hence severely under-perform when the channel is time varying. We then propose FastBeam, a suite of strategies that in tandem enable fast and practical beamforming using only RSSI measurements. FastBeam consists of both optimality preserving techniques and heuristic approaches that are selectively applied depending on the rate of change of the channel. We implement FastBeam on a Phocus Array System with eight antennas and use experimental evaluations to study its performance.