Outage performance of dynamic spectrum access systems with energy harvesting transmitters

We consider a two-hop primary network with a multi-antenna primary base-station (PBS) communicating to its distant primary receiver (PR) through a relay, and a secondary network with one of several energy harvesting secondary transmitters (STs) communicating to the secondary base-station (SBS). In this paper we propose a novel framework where the PBS utilizes its excess available power to charge a ST so as to enable it to share its spectrum. In this framework, the PBS employs beamforming to facilitate energy harvesting by a selected ST in the first hop while forwarding information to the relay. In the second hop, while the relay communicates to PR, the selected ST employs dynamic spectrum access (DSA) to communicate to its SBS. Such a framework can be expected to help the primary network earn revenue for both energy transfer and spectrum sharing. Assuming peak interference power constraints, we derive an expression for the outage probability of the secondary link. We also derive a simple expression for the outage floor. A simple intuitive user-selection scheme is suggested. It is shown that secondary user-selection can greatly enhance performance.