RIS-assisted dual-hop relaying for coverage enhancement in next-generation wireless networks over fluctuating Nakagami-m channels

Reconfigurable intelligent surfaces (RISs) have emerged as a promising technology for enhancing the coverage, reliability, and spectral efficiency of next-generation wireless networks. This paper investigates the performance of a dual-hop RIS-assisted relaying system operating over heterogeneous fading channels, where the source-relay link is assisted by an RIS and the relay-destination link experiences fluctuating Nakagami- m fading. Both amplify-and-forward (AF) and decode-and-forward (DF) relaying protocols are considered. Closed-form analytical expressions for the outage probability, average bit error rate, and average channel capacity are derived using advanced statistical tools and Meijer- G function representations. To provide further insights, high-SNR asymptotic expressions are obtained, from which the diversity order and coding gain are characterized. In addition, practical deployment aspects including imperfect channel state information, spatial correlation among RIS elements, and Active RIS-assisted relaying are investigated. Monte Carlo simulations are performed to validate the analytical results. The results reveal that increasing the number of RIS reflecting elements, improving the fading conditions, and reducing the shadowing severity significantly enhance system performance. Furthermore, DF relaying consistently outperforms AF relaying in terms of reliability and capacity, while Active RIS deployment provides additional performance gains compared with conventional passive RIS configurations. The presented analysis offers useful design insights for the deployment of RIS-assisted cooperative relaying systems in future intelligent wireless networks.