Comparative Analysis of Different Control Techniques for the Both-Sides Retrodirective Beamforming System

The both-sides retrodirective array is a beamforming technique that achieves maximum power delivered from a sending node to a receiving node. It can be used in wireless power transfer and wireless communications. The system can achieve fast beam convergence and maximum transfer efficiency operation for any given channel setting without explicit channel estimation. However, the system must maintain marginal stability to continuously operate at this optimal condition, which requires proper transmit gain settings on both arrays. In this paper, we explored two control schemes to drive the system to this marginally stable state, one based on linear quadratic control and another on fuzzy logic control. Both controllers were designed and tested in time-domain simulations to determine their performance in different channel settings. Simulation results show that the proposed system was more consistent and faster in achieving the maximum efficiency condition when compared to other existing beam focusing methods asserting that the proposed control schemes can realize the advantages of both-sides retrodirective array as a beamforming system.