Distributed RF Beamforming for Wireless Power Transfer Over Time Varying Channels

Distributed beamforming is a promising technique for transferring power to a node wirelessly, as it allows optimal design of waveforms at each transmitter such that they interact constructively at the receiver node. In this paper, we propose a distributed RF beamforming scheme which involves phase detection and prediction for the sources participating in beamforming process. The proposed method is capable of tracking source drifts and statistical fluctuations of the channel. The phase detection process requires one feedback for synchronizing all the sources to the receiver pairs and provides a closed-form solution for the phase offsets between a pair of received beams under the presence of RF power measurement errors. Autoregressive (AR) model is used for phase prediction which avoid feedback in synchronization process all together. Performance of the proposed detection and prediction model is quantified in terms of average received power, efficiency, and number of message exchange between the sources and the receiver.