Performance Analysis of UAV-Based IRS-Assisted FSO Communication Systems

This work analyzes the performance of a hovering unmanned aerial vehicle (UAV)-based intelligent reflecting surface (IRS)-assisted free-space optics (FSO) communication system. The impact of UAV hovering on both the IRS and receiver (<tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{R x}$</tex>) nodes is modeled, accounting for angle-of-arrival (AoA) fluctuations, path loss, atmospheric turbulence, and pointing errors. Atmospheric turbulence is characterized using the doubly inverted Gamma-Gamma (IGGG) distribution, and independent fading statistics are incorporated for the Tx-to-IRS and IRS-toRx links. Closed-form expressions for outage probability, average symbol error rate (ASER), and ergodic capacity are derived. The analysis demonstrates that the UAV based IRS-FSO system is highly sensitive to AoA fluctuations at both the IRS and Rx nodes, emphasizing the critical importance of accounting for these factors in practical implementations. Furthermore, it is observed that increasing the number of IRS elements significantly enhances the system performance, outperforming both decode-and-forward (DF) and amplify-and-forward (AF) relaying techniques. All the derived analytical expressions are validated through Monte-Carlo simulations.