Wireless-Powered Cooperative Systems With Relay Selection in Spectrum-Sharing Scenario

In this paper, we consider problem of relay selection in cognitive decode-and-forward (DF) relay networks subject to independent non-necessarily identically distributed Rayleigh fading. Specifically, we consider two variations of DF relay selection, namely best relay selection and partial relay selection, when the secondary transmissions are subject to interference from primary transmitter (PT) and transmissions of the secondary source and relay are powered by the energy harvested from radio frequency (RF) signal sent by the PT. For both these variations, we derive analytical expressions for the secondary delay-constrained throughput under the primary outage constraint and the peak power constraint at both secondary source node and secondary relay node. In order to shed insights into the systems performance, closed-form expressions for delay-constraint throughput of the noise-limited case are also derived for both relay selection strategies. The correctness of the proposed analysis is corroborated via Monte Carlo simulations and allows us to evaluate the impact of the key system parameters on the end-to-end performance.