This paper analyzes the performance of a satellite-terrestrial free-space optical (FSO)/millimeter wave (MMW) radio frequency (RF) relaying system with amplify-and-forward (AF) and decode-and-forward (DF) relaying. The Málaga ( $\mathcal {M}$ ) distribution with pointing error impairments and the multi-cluster fluctuating two-ray (MFTR) fading model are introduced to characterize the FSO link for both heterodyne detection (HD) and indirect modulation/direct detection (IM/DD) and MMW link, respectively. Therefore, the precise closed-form expression of end-to-end signal-to-noise ratio (SNR) for the outage probability (OP), average bit error rate (BER), ergodic capacity (EC) and effective capacity (EFC) is derived. In addition, we present an asymptotical result analysis for the OP and average BER at high SNR in terms of simple functions. Finally, we employ Monte-Carlo (MC) simulation results to verify all our analytical results.

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 ( $\mathcal {M}$ ) 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.