Outage Analysis of RIS-equipped RF-FSO Mixed Cooperative Communication System Over Nakagami-m Fading

This paper studies the outage performance of a RIS-equipped RF-FSO relaying system in the uplink scenario, employing robust opportunistic scheduling at the RF source. The specified system model can be employed in military operations, land-sea, and any difficult non-plain area where the optics fiber cannot be installed. This analysis considers the general fading channel, i.e., Nakagami-m fading against RF and the Gamma-Gamma fading against the FSO channel. Outage analysis is done under heterodyne detection (HD). The expression for the outage probability is derived. The result shows that the outage performance improves by increasing the number of users and RIS-reflecting elements, respectively. The effect of the pointing error parameter and the fading severity parameter shows that increasing its magnitude improves the outage performance. The analytical result derived in this paper is validated by using Monte-Carlo simulations.