Virtual Full-Duplex Cooperative NOMA: Relay Selection and Interference Cancellation

Abstract

In this paper, we propose a virtual full-duplex cooperative non-orthogonal multiple access (NOMA) framework for a downlink two-hop network assisted by multiple half-duplex decode–and–forward (DF) relay stations (RSs). In the proposed virtual full-duplex framework, the RSs except for a selected RS to forward the received signal suffer from inter-RS interference since both the BS and the selected RS transmit the super-imposed signal simultaneously. To address this problem, we propose an RS selection algorithm with adaptive inter-RS interference management and we mathematically attain the closed-form outage probability, which is challenging in general. In addition, we investigate diversity-multiplexing tradeoff (DMT) performance of a modified version of the proposed RS selection algorithm based on a discrete Markov chain, which adaptively resets the successive transmission. Simulation results show that the proposed RS selection algorithm outperforms the conventional cooperative NOMA algorithm in terms of both the outage probability and the DMT, which has the best performance reported in the literature.