Optimal Power Allocation for Downlink NOMA Heterogeneous Networks to Improve Sum Rate and Outage Probability

Heterogeneous networks (HetNets) have an increased data rate, improve quality-of-service (QoS), lower latency, and use less power for future wireless networks. Despite the benefits, there are various problems in HetNets, with interference being one of the most prominent. Densification in HetNets increases interference while decreasing rate and outage probability. As a result, non-orthogonal multiple access (NOMA) based HetNets may be employed to minimize cross-tier interference. Thus, decreasing outage probability and increasing the system sum rate in order to fulfill future wireless communication needs. Power allocation (PA) is critical for increasing system throughput and reducing outages in a NOMA network. Hence, this study comes up with an optimal PA for downlink transmission NOMA-based HetNets in order to optimize the system’s sum rate and outage probability while adhering to the minimal user rate constraint. We derived a generalized optimum PA coefficient equation for small cell users of NOMA-based HetNets. Then, utilizing the PA coefficient equation, we presented an algorithm to optimize the sum rate and minimize the outage probability. To apply our algorithm in real-world wireless networks, we ensure that our algorithm is both fast and minimal in complexity. Finally, we illustrate simulation outcomes for the proposed method and compare them to OMA systems.