Passive Multi-Rectenna Channel Estimation Based on Beam-Spatial Smoothing for Microwave WPT

This paper proposes a novel passive multi-rectenna channel estimation method based on beam-spatial smoothing. The proposed method assumes cooperative/selective wireless power transfer using multiple wireless stations: one station transmits high-/low-power binary pilot signals with multiple beam patterns. Due to the rectenna non-linearity, the other receives pseudoload-modulated backscattered signals from the multiple rectennas. Then, multi-rectenna channels can be estimated from the correlation matrix of the received signals through beam-spatial smoothing. Ray-tracing simulation shows the proposed method achieves accurate channel estimation and high transfer efficiency.