Performance analysis of non-linear energy harvesting cognitive two-way relay network based on NOMA

In this paper, we propose an underlay non-orthogonal multiple access (NOMA) network with an energy harvesting (EH) based two-way relay (TWR) for wireless sensor networks. The two NOMA sensors exchange information simultaneously through the TWR which harvests energy from the radio frequency signal of a power beacon by using a piecewise linear EH model. Considering instantaneous channel state information (CSI) and statistical CSI available, respectively, we derive approximate analytical expressions for the outage probabilities of the two NOMA sensors and the delay-limited sum-throughput of the secondary network. It is seen that the optimal selection of target end-to-end rates, power allocation coefficients, and EH time ratio is crucial for maximizing sum-throughput. Extensive Monte Carlo simulations are performed to corroborate our analytical results.