Performance Analysis of RIS-Aided FSO/RF Hybrid Satellite-Terrestrial Network With Imperfect CSI

This study proposes an uplink reconfigurable intelligent surface (RIS)-aided free-space optical (FSO) and radio frequency (RF) hybrid satellite-terrestrial network (HSTN). We consider the impact of imperfect channel state information (CSI) on the RIS system under fixed-gain amplify-and-forward (AF) and decode-and-forward (DF) relay conditions. We derive closed-form expressions for various performance metrics of the end-to-end signal-to-noise ratio (SNR). We model the FSO link using the Málaga (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\mathcal {M}$</tex-math></inline-formula>) distribution with two detection schemes and use an RIS-aided Rayleigh fading model for the RF link, both of which consider the satellite-terrestrial loss. At high SNRs, we determine the relevant asymptotic expressions and validate the analytical results through Monte Carlo simulations. Additionally, we evaluate the impacts of key system parameters, such as RIS configuration parameters and imperfect CSI, on the end-to-end performance.