Outage and throughput analysis of power-beacon assisted nonlinear energy harvesting NOMA multi-user relay system over Nakagami-m fading channels

Abstract

This paper considers a non-orthogonal multiple access (NOMA) multi-user relay system where both source and relay harvest the energy from a power beacon (PB) equipped with multiple antennas and use this harvested energy to transmit signals to several users. Realistic nonlinear energy harvesting models are applied, and time switching protocols are adopted at source and relay. We successfully derive the exact closed-form expressions of the outage probability and throughput of the system over Nakagami-m fading channels. Then, we use Monte-Carlo simulations to validate the correctness of these derived mathematical expressions. Numerical results show that a higher saturated power threshold of the nonlinear energy harvester results in lower outage probability and higher throughput. Moreover, the optimal time switching ratio that maximizes the throughput is smaller than the optimal time switching ratio that minimizes the outage probability.