Interference Modeling and Outage Analysis for 5G Downlink NOMA

Abstract

Non-orthogonal multiple access (NOMA) is a promising multiple access scheme to increase the system capacity for future fifth generation (5G) communication systems. However, NOMA with receivers employing conventional successive interference cancellation (SIC) technique requires a careful choice of target rates and power allocation coefficients in order to keep NOMA operational. In this paper, we represent downlink (DL) NOMA system in a novel way by proposing an equivalent transmission model, which is then utilized for interference modeling and estimation using stochastic geometry. Furthermore, we derived the closed-form expression for analyzing the outage performance of DL users. Numerical results show that with the proposed interference model and its application to estimate and remove the interference in the DL signal before decoding, NOMA not only outperforms its orthogonal multiple access (OMA) counterpart, but also manages to continue operating under conditions where NOMA with conventional SIC receiver suffers complete outage.