Channel-Aware Artificial Intersymbol Interference for Enhancing Physical Layer Security

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.