Outage Performance of Full-Duplex Unmanned Aerial Vehicle-aided Cooperative Non-orthogonal Multiple Access

Abstract

Unmanned Aerial Vehicles (UAVs) are envisioned to play a key role in the Sixth-Generation (6G) and Beyond Fifth-Generation (B5G) networks. Resolving spectrum constraints in UAV communications remains a critical issue. This article investigates Full-Duplex (FD) UAV-aided Non-Orthogonal Multiple Access (NOMA) to effectively utilise the scarce wireless spectrum. Specifically, exact closed-form formulas for the outage probability of FD UAV-aided NOMA have been developed. The results are validated using Monte Carlo simulation in 3GPP UMi conditions to provide practical guidelines for real-world deployment. In low transmission power regimes, the results also reveal that FD UAV-aided NOMA has a lower outage probability at the downlink Ground Users (GUs) than HD UAV-aided NOMA. At high transmit power regimes, FD UAV-aided NOMA is limited by residual SI at the UAV and interference from the UAV to the GUs. The numerical results also show that the transmission power at the UAV should be significantly lower than that at the Ground Base station (GB) to ensure low outages at the GUs.