Effect of Power Amplifier Nonlinearity on the Physical Layer Security of MIMO Systems

This paper presents an analytical investigation on the effect of nonlinear high-power amplifiers on the physical layer security of multiple-input-multiple-output (MIMO) wiretap channels with orthogonal space-time block code (OSTBC). The performances of the MIMO-OSTBC system are evaluated under Rayleigh fading channels when the eavesdropper channel is uncorrelated with the main one. Analytic closed-form expressions for the secrecy outage probability (SOP) and the probability of strictly positive secrecy capacity are delivered. In order to obtain the secrecy diversity order and the secrecy array gain, an asymptotic SOP expression is also derived. Simulation results are provided to validate our analytical analysis and show an excellent agreement between numerical results and Monte-Carlo simulation curves. Furthermore, the impact of the nonlinearity factors on the SOP performances is discussed.