Wireless Energy Harvesting in Cognitive AF Network With Relay Selection

Abstract

In this paper, we propose an improved cognitive amplify-and-forward relaying model, in which the multiple secondary users can harvest energy from the primary network, assisting primary user transmission and meanwhile performing secondary transmission in a spectrum-sharing network. One secondary user having highest harvested energy among multiple secondary users will be selected as a relay to broadcast information. The outage probabilities (OP) of the primary and secondary network are investigated to evaluate the performance of network over Rayleigh fading channels. In particularly, we derive the analytical expression of OP for primary and secondary network. Moreover, the closed-form expression of lower bound for OP at secondary user is obtained. Analysis results are validated by the Monte-Carlo simulation results, which show that the improved cognitive radio model and the number of relays have significant improvement in the system OP.