Toward UAV-Assisted 3D UL-Heavy NOMA for Low-Altitude Economy: Joint Bandwidth, Power Allocation and Stereoscopic Trajectory Design

In this paper, we study an uncrewed aerial vehicle (UAV)-assisted 3D uplink (UL)-heavy non-orthogonal multiple access (NOMA) system for low-altitude economy, in which UL communication is growing more crucial in emergency hotspots like football stadiums. To the best of our knowledge, this is the first effort to investigate joint UL resource allocation alongside stereoscopic trajectory design for UAV-assisted 3D UL-heavy NOMA, in light of users' instantaneous rate-sensitive and elevated average rate-oriented traffic requirements. Specifically, we put forward a joint bandwidth and power allocation (J-BPA) algorithm by demonstrating that the inter-user interference within each NOMA group can be inherently eliminated while deriving users' UL sum-rate. Given the non-differentiable nature of the Lagrange dual function, the constrained ellipsoid method is employed to obtain the optimal solution. Furthermore, to further reduce computational complexity and boost the degrees of freedom in resource allocation, an enhanced J-BPA scheme is proposed, with closed-form optimal expressions derived for both intra-group and inter-group power allocation among NOMA groups. Both the proposed J-BPA and enhanced J-BPA are compatible with stereoscopic trajectory optimization, which are alternatively solved to achieve rapid convergence, and demonstrate superior performance over existing methods in terms of minimum average UL rate and user fairness.