RF/FSO and THz/FSO Relaying Systems

This chapter delves into the potential of relay-assisted transmission to alleviate fading in free-space optical (FSO) systems. We focus on evaluating the efficacy of a dual-hop relay system for RF (millimeter-wave and terahertz)/FSO (RF/FSO) communications in the presence of pointing errors. We construct an integrated channel model that accounts for various factors, encompassing pointing errors, channel fading, and deterministic path loss. More specifically, the RF link undergoes α − μ fading with pointing errors, while the FSO link is subject to ΓΓ fading and pointing errors. Employing amplify-and-forward relaying, we derive mathematical expressions for the probability density function and cumulative distribution function of the end-to-end signal-to-noise ratio, considering the collective effect of pointing errors and channel fading. Utilizing the derived statistical expressions, we assess critical performance metrics, including the outage probability, average bit error rate, and ergodic capacity for the relaying schemes under consideration. To validate our analytical conclusions, we perform Monte Carlo simulations. The results highlight a robust correlation between the system’s performance, specific pointing errors, and fading parameters associated with the RF/FSO connections.