Performance Analysis of Distributed Uplink NOMA

We propose an optimal joint user association and decoding order selection scheme for distributed uplink non-orthogonal multiple access (DU-NOMA) with fixed transmission rates. It is considered that the remote radio heads can either perform decoding independently from each other or exchange information via a dedicated feedback link with limited capacity. The outage probability is derived in closed-from and useful insights for the high signal-to-noise ratio regime are provided. Finally, it is illustrated that DU-NOMA with feedback together with the proposed coordination scheme achieves substantial gain compared to DU-NOMA without feedback. Also, in most of the practical cases it outperforms orthogonal multiple access schemes, even if the feedback link is not error-free.