Physical Layer Security for Terahertz Wireless Communications with Antenna Misalignment

Terahertz (THz) wireless communication is envisioned to revolutionize next-generation networks, offering ultra-wide bandwidths and exceptional data rates. With its highly directional narrow beams, THz communication supports dense network deployments while providing inherent physical layer security (PLS). However, the vulnerability of THz systems to high path-loss and antenna misalignment poses significant challenges to their performance and security. This letter presents a comprehensive analytical framework to evaluate the secrecy performance of THz wireless communication systems, accounting for the effects of antenna misalignment errors. We derive exact expressions for the probability density function (PDF) and cumulative distribution function (CDF) of the signal-to-noise ratio (SNR), reflecting the joint impact of channel fading and antenna misalignment on the THz wireless channel. Further, utilizing these results, closed-form expressions for the secrecy capacity and secrecy outage probability are obtained. The analytical results are validated through simulations, offering insights into the effect of channel impairments on system security performance. Finally, design recommendations are provided to enhance the secrecy performance of THz communication systems.