On the Performance of Nth Best Relay Selection Scheme for NOMA-Based Cooperative Relaying Networks with SWIPT

In this paper, we analyze the performance of a NOMA-based cooperative relaying network with the Nth best relay selection scheme over Rayleigh fading channels. In addition, the simultaneous wireless information and power transfer (SWIPT) technique is applied to prolong the work time of the relay. Some closed-form expressions as well as the asymptotic analysis for the outage probability are derived. These analysis reveals that the diversity order achieved by the Nth best relay selection scheme is M -N +1, where M is the number of all the relays and N is the order number. Monte Carlo simulation results verify our theoretical analysis and demonstrate the impact of the number of the relays, the order number, and the power-splitting ratio on the outage performance of our considered system.