On the performance of cognitive underlay RF/FSO communication systems with limited feedback

Abstract

In this work, we consider an underlay cognitive radio (CR) RF/free space optical (FSO) network where the unlicensed secondary user (SU) wishes to communicate with a specific destination node with the aid of an optical path over a selected relay terminal without causing any interference to the primary user (PU). The proposed structure can be viable for metropolitans where an unlicensed user wishes to transfer its information to a specific destination node which is connected to the backbone network over an optical path. For the proposed structure, closed form and approximate outage probability and ergodic capacity expressions are derived for Nakagami-m/Exponentiated Weibull fading channels. The results show that the transmission capacity of the SU depends on the weather conditions and the number of relays in the system.