Performance optimisation of RF energy harvesting relay-based interweave/underlay cognitive radio network

This paper investigates the performance of energy harvesting (EH) relay-based interweave/underlay cognitive radio network. The relay employs amplify and forward (AF) technique along with time-switching relaying protocol (TSR) for EH. Based on sensing accuracy, we derive an expression for optimisation of charging duration TSR parameter and sensing duration for maximising throughput of interweave cognitive radio (CR). Based on sensing efficiency, throughput and outage probability for underlay CR is analysed considering the interference temperature constraints and optimal power distribution parameter at secondary user (SU) terminals. Variations in the sum-rate and detection probability are considered in terms of cumulative distribution functions (CDF) of the terminal Signal to Noise Ratios (SNRs). We prove that erogodic sum-rate is maximised in underlay CR case, when interference power distribution parameter is half across the SU terminals. The optimised values of switching-time ratios have been derived analytically for both interweave and underlay CR. The results thus obtained are compared by taking symmetrical and asymmetric channels between SU terminals. Analytical results are validated through Monte-Carlo simulations to confirm the accuracy of the derived expressions.