RF-Powered Green Cognitive Radio Networks: Architecture and Performance Analysis

In this letter, we consider an RF-powered green cognitive radio network (RF-GCRN), where a central node, called a power beacon (PB), harvests green energy from ambient sources and wirelessly delivers random harvested energy to cognitive users. Random in-band energy transmission by PB is the only energy source of cognitive users. Performance of this network, with a single pair of secondary users, is analyzed under two spectrum access schemes, i.e., random access and spectrum sensing-based access schemes. Results show feasibility of the RF-GCRN model, if the energy transmission rate is below a certain threshold. This threshold is determined according to maximum tolerable delay of primary user and parameters of spectrum access scheme. Finding a closed form expression for this threshold results in a quite complicated formula, which cannot be helpful in determining feasibility region, due to excessive complexity. Instead, we numerically calculated feasibility regions of both access schemes to facilitate parameter selection process.