Secret Key Generation Scheme Based on the Channel Covariance Matrix Eigenvalues in FDD Systems

In this letter, an efficient secret key generation (SKG) scheme exploiting the eigenvalue reciprocity of uplink (UL) and downlink (DL) channel covariance matrices in frequency division duplex (FDD) systems is developed. Our proposed method achieves a better performance in terms of SKG rate and secret key disagreement (SKD) ratio compared with the loopback method in the previous literature, meanwhile free from the security issue of loopback strategies. Numerical simulation results are presented to verify the feasibility and effectiveness of the proposed scheme.