Dual-Hop Mixed FSO-RF Wireless Powered Relaying System: Performance Analysis With Nonlinear Energy Harvesting

Energy harvesting (EH) extends device lifespan and reduces carbon emissions in wireless communication. Non-linear EH overcomes not only sensitivity and saturation issues, surpassing linear EH but also power beacon (PB)-based wireless power transfer challenges. In contrast to commonly used linear EH in existing work, in this considered fee-space optical-radio frequency (FSO-RF system), non-linear EH is used, wherein a source node communicates with a user (destination) through a single-aperture, single-antenna relay that harnesses energy from a PB. Gamma-Gamma and Nakagami-m fading models, respectively, characterize the FSO-RF channels. The closed-form expressions for the Outage Probability (OP) and the Average Bit Error Rate (ABER) are derived considering atmospheric turbulence and pointing errors. Additionally, asymptotic analysis is conducted for OP to ascertain the diversity order. The system performance with various detection methods, pointing errors, atmospheric turbulence levels and the energy harvester’s saturation threshold is investigated. Monte Carlo simulations validate the theoretical findings. Results indicate that HD detection outperforms IM/DD in reducing OP. Moreover, increasing pointing error, decreasing turbulence strength, elevating fading severity, and raising the saturation threshold contribute to OP reduction. Furthermore, weaker turbulence and higher pointing error parameters exhibit superior ABER performance.