  This work studies and optimizes the performance of reconfigurable intelligent
surface (RIS)-aided networks in Nakagami-m fading environment. First, accurate
closed-form approximations for the channel distributions are derived. Then,
closed-form formulas for the system outage probability, average symbol error
probability (ASEP), and the channel capacity are obtained. Furthermore, we
provide three different optimization approaches for finding the optimum number
of reflecting elements to achieve a target outage probability. At the high
signal-to-noise ratio (SNR) regime, a closed-form expression for the asymptotic
outage probability is obtained to give more insights into the system
performance. Results show that the considered system can achieve a diversity
order of (a+1)/2, where a is a function of the Nakagami-m fading parameter m
and the number of reflecting elements N. Moreover, findings show that m is more
influential on the diversity order than N. Finally, the achieved expressions
are applicable to non-integer values of m and any number of meta-surface
elements N.
