Physical Layer Security for THz Communication

Terahertz (THz) band offers large accessible bandwidth and spatially confined highly directed beams for the realization of secure and high data rate communication. In this work, the secrecy performance is investigated for a directional THz link, which suffers from high propagation loss and attenuation due to molecular absorption. The statistical characterization of the THz link is also considered for analyzing the system over precise channel model. A threat model is developed for the scenario where the main intended user and the eavesdropper (eve) are located in line-of-sight (LOS) with respect to the source. The performance analysis is carried out by deriving the probability of strictly positive secrecy capacity (SPSC) and the lower bounds of secrecy outage probability (SOP). The proposed theoretical expressions are validated using extensive Monte-Carlo simulations. The results demonstrate that limiting the broadcast range and tuning the frequency are powerful yet simple transmission protocols that can achieve the physical layer security in the THz bands.