Beamforming with Beam-Steered Pilots in a Wireless Power Transfer System

In an RF wireless power transfer system, transmit beamforming can improve energy transmission efficiency by concentrating radiated energy toward a receiving device. For optimal transmit beamforming, it is necessary for the energy transmitter to know the exact direction of the receiving device. In this paper, we propose a wireless power transfer system based on beam-steered pilot signals. In the proposed system, the receiver estimates its own direction relative to the transmitter using the beam-steered pilot signals and feeds the estimate back to the transmitter. Then, the transmitter emits beamformed energy signals to the corresponding direction. We evaluate the effect of the resolution of beam-steered pilot signals on the performance of the direction estimation scheme and analyze the efficiency of wireless power transfer.