On the performance of 5G non-orthogonal multiple access for vehicular communications at road intersections

Road traffic safety is a crucial issue, and more specifically at road intersections. At the same time, vehicular communications (VCs) are attracting a great attention thanks to their useful safety applications. In this paper, we study the performance of VCs at intersections, in the presence of interference when the communication system implements a non-orthogonal multiple access (NOMA) scheme. First, we derive the outage probability and the average achievable rate for a scenario involving a source node and two destination nodes, when the destination nodes can be either on the roads or outside the roads. Then we extend the derivations for K destination nodes. Closed form expressions are obtained for the outage probability and quasi-closed form expressions are obtained for average achievable rate. The analysis takes into account both perfect and imperfect successive interference cancellation (SIC). We show that the outage probability increases and the average achievable rate decreases when vehicles move toward the intersection. We also compare the performance of VCs at intersections and at highways, and show that the performance of VCs at intersections is worse than at highways. We compare NOMA with orthogonal multiple access (OMA) in VCs, and show that NOMA outperforms OMA in terms of outage probability and average achievable rate. We also show that the benefit of NOMA over OMA becomes greater for high data rates. However, we show that NOMA performance decreases drastically when the system parameters do not respect certain conditions. All the analytical results are validated by Monte-Carlo simulations. (C) 2019 Elsevier Inc. All rights reserved.