Retrodirective Large Antenna Energy Beamforming in Backscatter Multi-User Networks

In this letter, we study a new technique for energy beamforming (EB) in multi-user networks, which combines large antenna retrodirectivity at the transmitter side with signal backscattering at the energy receivers. The proposed technique has low complexity and achieves EB without any active operation at the receivers or complicated signal processing techniques at the transmitter. Since the average harvested energy depends on the backscattering coefficients, we investigate different reflection policies for various design objectives. The proposed policies are analyzed from a system level standpoint by taking into account spatial randomness.