Self-Interference Channel Hermitian Product Estimation Based on Power Feedback in Full-Duplex Phased Arrays

The estimation of self-interference (SI) channel state information (CSI) is a significant challenge for full-duplex analog phased arrays. Instead of collecting CSI, an SI channel Hermitian product (CHP) estimation method is proposed to estimate the product of the SI channel matrix and its conjugate transpose matrix based on SI power feedback. CHP estimation can be accomplished in traffic time slots with little need for additional dedicated time slots. Hence, channel changes can be tracked in time. Furthermore, a low-complexity solution for the optimal transmit beamforming (TxBF) weight is provided on the basis of CHP estimation results. Simulations are based on actual SI channel measurements from a hardware prototype testbed. The results verify the effectiveness of the CHP estimation and TxBF optimization methods.