Channel-Aware Artificial Intersymbol Interference for Enhancing Physical Layer Security

Abstract

In this letter, we propose a novel scheme for enhancing the security of the information transfer between resource-limited devices. We select a pulse from a set of $T$ -orthogonal pulses for shaping the data at source ( $S$ ) based on legitimate channel state information (CSI). A destination ( $D$ ) having the CSI, properly samples the output of the matched filter. An eavesdropper ( $E$ ) having no knowledge of the legitimate CSI, may or may not sample correctly, thereby, inducing artificial intersymbol interference (ISI) at the $E$ . We also consider a case where the $S-E$ link is correlated with the $S-D$ link (when $E$ and $D$ are closely located). We derive optimal thresholds at $E$ , $S$ for switching the selection of a pulse in maximizing and minimizing the achievable rate at $E$ , respectively. We derive closed-form expressions for upper bound and lower bound on the secrecy outage probability (SOP) for the independent case. Simulation results show that unlike at $D$ , the symbol error rate (SER) at $E$ saturates at a high SER due to the induced ISI.