A full-duplex cooperative scheme with distributed switch-and-stay combining for NOMA networks

In this paper, we study performance and reliability improvement for a cell-edge user in downlink scenarios of two-user non-orthogonal multiple access (NOMA) networks. To this end, we propose a full-duplex (FD) cooperative scheme, in which a near user acts as a FD relay to forward source's signals to a far user, while the far user employs distributed switch-and-stay combining (DSSC) technique to process the incoming signals. We then investigate the performance of the far user in terms of outage probability (OP). In particular, we obtain a closed-form expression for the OP of the far user as well as its asymptotic OP. The developed analysis is corroborated through Monte-Carlo simulation. Numerical results reveal that the proposed scheme achieves better outage performance in comparison with conventional NOMA systems. It is also showed that the choice of the switching threshold used in DSSC technique and/or the target data rate of the system sensitively affects the outage performance of the proposed scheme.