Performance Analysis of Passive/Active RIS Aided Wireless-Powered IoT Network With Nonlinear Energy Harvesting

A reconfigurable intelligent surface (RIS) tames the wireless propagation environment and emerges as a key enabler for beyond fifth-generation communication systems. In this paper, the performance of a wireless-powered Internet-of-Things (IoT) network is studied under the assistance of passive and active RIS. In particular, a nonlinear energy harvesting (EH) model is employed at the IoT devices, which harvest radio frequency energy from a dedicated energy station. The analytical expression of outage probability (OP) is derived in terms of the Meijer-G function over-generalized Nakagami- m fading channels. The asymptotic (high signal-to-noise ratio) OP is also analytically characterized, and the diversity order of the considered network is obtained. Further, sum throughput and energy efficiency expressions are derived for delay-limited and delay-tolerant transmission modes, while the ergodic capacity is derived analytically by employing the Gaussian Chebyshev quadrature approximation. The performance attained under the considered nonlinear EH model is compared to that attained with a traditional linear EH model, which is impractical. Finally, the derived analytical expressions are verified via Monte-Carlo simulations.