Performance Analysis of Multi-RIS-Aided Fluid Antenna Systems Under Nakagami-$m$ Fading Channels

Recognizing the vast potential of combining reconfigurable intelligent surfaces (RIS) with fluid antenna system (FAS), we study the communication performance of multi-RIS-aided FAS under Nakagami-<tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$m$</tex> fading channels. Specifically, in the presence of a direct link, a base station with fixed single-antenna transmits information through multi-RIS to a user with FAS to aid communication. Considering the correlation among the ports of FAS, we first obtain that the equivalent channel gains for different ports obey the gamma distribution and are correlated. Then, we derive the joint cumulative distribution function of the correlated equivalent channel gain and the outage probability of the system by using the Archimedean copulas functions cluster. Finally, numerical results not only indicate that in multi-RIS-aided wireless networks, FAS can significantly improve the outage performance compared to traditional antenna systems, but also reveal that spatially correlated copula structures have a significant impact on outage performance.