Performance Analysis and Optimization of Multi-RIS-Aided UAV Networks

In this paper, we study the performance of multiple reconfigurable intelligent surfaces (RISs)-aided unmanned aerial vehicle (UAV) communication networks over Nakagami-$m$ fading channels. For that purpose, we used accurate closed-form approximations for the channel distributions to derive closed-form approximations for the outage probability (OP), average symbol error probability (ASEP), and the average channel capacity assuming independent non-identically distributed (i.ni.d.) channels. Furthermore, we derive the asymptotic OP at the high signal-to-noise ratio (SNR) regime to get more insights into the system performance. We also study some practical scenarios related to RISs, UAV, and destination locations and illustrate their impact on the system performance through simulations. Finally, we provide an optimization problem on the transmit power of each channel.

Multiple RISs-Aided Networks: Performance Analysis and Optimization

This paper analyzes the performance of multiple reconfigurable intelligent surfaces (RISs)-aided networks. The paper also provides some optimization results on the number of reflecting elements on RISs and the optimal placement of RISs. We first derive accurate closed-form approximations for RIS channels' distributions assuming independent non-identically distributed (i.ni.d.) Nakagami-\emph{m} fading environment. Then, the approximate expressions for outage probability (OP) and average symbol error probability are derived in closed-form. Furthermore, to get more insights into the system performance, we derive the asymptotic OP at the high signal-to-noise ratio regime and provide closed-form expressions for the system diversity order and coding gain. Finally, the accuracy of our theoretical analysis is validated through Monte-Carlo simulations. The obtained results show that the considered RIS scenario can provide a diversity order of $\frac{a}{2}K$, where $a$ is a function of the Nakagami fading parameter $m$ and the number of meta-surface elements $N$, and $K$ is the number of RISs.