Secure mm-Wave Communications with Imperfect Hardware and Uncertain Eavesdropper Location

Abstract: This paper examines the secrecy performance of millimeter-wave (mm-Wave) communications with imperfect hardware and uncertain eavesdropper location. We consider a multiple-antenna source communicating with a single-antenna destination using masked beamforming to transmit the information signals with artificial noise (AN) in the presence of a passive eavesdropper (Eve). For this system, we derive new expressions for the secrecy outage probability (SOP) and secrecy throughput with mm-Wave multipath propagation under slow-fading channel conditions and hardware imperfections. Based on this, optimal power allocation (OPA) solutions are derived for the information and AN signals aimed at minimizing the SOP and maximizing the secrecy throughput. Our results reveal that it is non-trivial to achieve an OPA solution for the general scenario of imperfect hardware. We also highlight that our proposed masked beamforming with OPA scheme significantly enhances the secrecy throughput compared with the benchmark schemes of maximal-ratio transmission and equal power allocation.