Overlay Cognitive Radio Networks Enabled Energy Harvesting With Random AF Relays

In this paper, we investigate an overlay cognitive radio network (CRN) in which one user is selected among multiple secondary users (SUs) to harvest energy from primary transmissions using a time-switching protocol. Based on a power allocation scheme, the selected user utilizes a portion of the harvested energy to assist the primary user (PU) in forwarding its messages to a primary receiver, while the remaining portion is used to transmit its own information in exchange for this cooperation. Specifically, we evaluate the reliability of both the primary and secondary networks in terms of the outage probability. Moreover, both the time switching and power allocation factors that maximize the users’ data rate are optimized.