  As unmanned aerial vehicles (UAVs) are expected to play a significant role in
fifth generation (5G) networks, addressing spectrum scarcity in UAV
communications remains a pressing issue. In this regard, the feasibility of
full-duplex non-orthogonal multiple access (FD-NOMA) UAV communications to
improve spectrum utilization is investigated in this paper. Specifically,
closed-form outage probability expressions are presented for FD-NOMA,
half-duplex non-orthogonal multiple access (HD-NOMA), and half-duplex
orthogonal multiple access (HD-OMA) schemes over Rician shadowed fading
channels. Extensive analysis revealed that the bottleneck of performance in
FD-NOMA is at the downlink UAVs. Also, FD-NOMA exhibits lower outage
probability at the ground station (GS) and downlink UAVs than HD-NOMA and
HD-OMA under low transmit power regimes. At high transmit power regimes,
FD-NOMA is limited by residual SI and inter-UAV interference at the downlink
UAVs and FD-GS, respectively. The impact of shadowing is also shown to affect
the reliability of FD-NOMA and HD-OMA at the downlink UAVs.
