Coverage Probability Analysis of User Association in NOMA-Based Full-Duplex Systems

In this paper, we study user association in a full-duplex (FD) cellular network where the base station (BS) serves a set of near and far users via non-orthogonal multiple access (NOMA) technique. In order to reduce received interference at the NOMA downlink (DL) user caused by the NOMA uplink (UL) user we propose guard zone based user association scheme. In particular, we propose DL user associate based on the nearest near and nearest far scheme. In order to schedule the UL users, we assume a guard around the selected DL user with a specific radius. Finally, UL near and far users are randomly selected from those UL users located outside the guard zone, to upload their data packet to the BS. We derive closed-form expressions for the DL and UL coverage probability of the proposed scheme. Numerical results show that the DL coverage probability of the proposed scheme achieves up to 43% gain over the conventional NNNF scheme.