Coverage Analysis of Downlink NOMA-Enabled Dense Networks With ISP-Based User Ordering

In the existing non-orthogonal multiple access (NOMA) works, ordering users depending on their distances is widely used, which can provide tractable results. However, it is not accurate in dense networks with considering the line-of-sight (LoS)/non-line-of-sight (NLoS) propagation and multipath fading. Hence, the received instantaneous signal power (ISP)-based ordering is investigated in this letter. We derive the probability of the near user in distance-based ordering being the strong user in ISP-based ordering, which is termed as the accuracy probability, and also analyze the respective coverage probabilities. The analytical and simulation results show that the accuracy probability varies with base station (BS) density and the gap between the distance and ISP-based ordering highly depends on the BS density and power allocation coefficient.