Outage performance of NOMA over shadowed faded channels in interference limited scenario

In wireless communications networks, the non-orthogonal multiple access (NOMA) technique is different from the existing orthogonal multiple access (OMA) techniques. In NOMA, the available number of resources are more and it leads to multiple access interference. In this paper, initially we developed an analytical framework of interference for NOMA in terms of signal to interference ratio (SIR). Later, we asses the outage probability of NOMA based downlink communication system by considering the effect of interference. The outage probability of NOMA with fixed number of interferers is calculated for different channel propagation effects as Nakagami-m, Rayleigh faded channels with and without log-normal shadowing. The obtained outage probabilities with fixed number of interferers are used to calculate the outage probabilities with random number of interferers (total system outage probability) in different channel propagation effects. In this paper, we proposed a novel algorithm to calculate the total system outage probability for NOMA in different channel propagation effects by choosing different offered load in terms of Erlangs per cell. We calculate the analytical results of outage probability for two users which are at near and edge positions of the cell. The obtained analytical results are supported with simulated NOMA.