On the Performance of Two-Way Multiple Relay Non-Orthogonal Multiple Access-Based Networks With Hardware Impairments

In this paper, we investigate the performance of two-way multiple relay non-orthogonal multiple access (NOMA) based networks with hardware impairments (HIs). Especially, opportunistic relay selection scheme is applied to enhance the spectral efficiency along with the spatial diversity. With the increasing of relay's processing capacity, decode-and-forward (DF) protocol is considered in the networks. Based on the proposed relay selection scheme and NOMA protocol, the closed-form expressions for the outage probability (OP) of the system are derived. In order to study the energy efficiency (EE) of the system, simulation results for EE are also obtained. Furthermore, for the purpose of observing the impacts of HIs' level, NOMA protocol and the number of relays on the system performance at high signal-to-noise ratios (SNRs), the asymptotic expressions of the OP are also derived. Finally, Monte Carlo (MC) simulation results are presented to verify the correctness of the analytical results.