4-WFRFT for Physical Layer Security Enhancement Based on MIMO Correlated Channel

In this paper, 4-weighted-type fractional Fourier transform (4-WFRFT) technology is introduced into Multiple-input multiple-output (MIMO) correlated Rayleigh fading channel to enhance physical layer security (PLS) significantly. The MIMO correlated Rayleigh fading channel is built first, and then 4-WFRFT is introduced into correlated channel model while transmitter and receiver share transform order but eavesdropper cannot acquire the exact transform order, so there is estimate error at eavesdropper. In MIMO correlated channel while using 4-WFRFT, the signal-to-noise ratio (SNR) of receiver and eavesdropper are derived, then the average secrecy capacity (ASC) is derived, at last the simulation results are analyzed. It can be concluded that when the estimate error is not zero, 4-WFRFT technology can reduce the SNR of eavesdropper while the SNR of receiver is unaffected, so 4-WFRFT can increase ASC significantly. When estimate error is within [0, 1], the greater the estimate error is, the greater ASC is, but not the case within [1], [2]. But when the estimate error is zero, it means eavesdropper acquire the transform order shared by transmitter and receiver, 4-WFRFT cannot achieve the purpose of enhancing PLS.