THz-Enabled UAV Communications Under Pointing Errors: Tractable Statistical Channel Modeling and Security Analysis

Unmanned aerial vehicles (UAVs) are increasingly being utilized as mobile base stations for rapidly establishing temporary wireless coverage in emergency situations and remote locations. Their high mobility and flexibility make UAVs ideal for quickly deployed communication systems, but these features also introduce unique challenges, particularly in maintaining stable and reliable communication links. The highly directional nature of terahertz (THz) antennas introduces challenges in UAV communication systems. Combined with the mobility of UAVs, this can cause significant issues, such as beam misalignment and signal degradation. Thus, developing accurate radio channel models that address these challenges is critical to ensure reliable communication. In this study, we present an analytical framework focused on evaluating the security performance of highly directional THz-enabled UAV communication links. The challenges analyzed include misalignment of directional beams, path loss, small-scale fading, and UAV-induced vibrations. The small-scale fading is modeled using the $\alpha$–$\mu$ distribution, which accurately represents various fading environments. Using the Meijer G-function, we derive closed-form expressions for key statistical functions, including the probability density function (PDF) and cumulative distribution function (CDF) of the channel gain. Furthermore, a detailed physical-layer security analysis is provided, focusing on metrics such as average secrecy capacity, secrecy outage probability, and the probability of strictly positive secrecy capacity, particularly in the presence of UAV eavesdroppers. Numerical results validate the analytical expressions under different operational conditions, such as beam misalignment and fading, providing valuable insights into the security and performance of THz-enabled UAV communication systems. These results provide important guidelines for optimizing future wireless networks using UAVs and THz frequencies to ensure secure and reliable data transmission in dynamic environments.