Outage Probability of Reconfigurable Intelligent Surface Aided THz Communications

TeraHertz (THz) communications are envisioned to help satisfy the ever-high data rates demand with massive bandwidth. However, THz signals are sensitive to blockage. With the help of the recently proposed reconfigurable intelligent surface (RIS) technology, we investigate a RIS-aided THz communication system. More specifically, we first prove that we can use the fluctuating two-ray distribution to model the small-scale amplitude fading of THz signals based on recent measurements. Furthermore, a novel swarm intelligence-based method is proposed to optimize the phase shifts at the RIS elements under discrete constraints. Finally, we investigate exact statistical characterizations of end-to-end signal-to-noise plus distortion ratio and derive closed-form outage probability. Monte-Carlo simulations are provided to validate the accuracy of our results. It is interesting to find that the impact of path loss is more pronounced compared to others, and increasing the number of elements at the RIS can significantly improve the performance of the THz communications.