Network Service Provision Through Energy-Efficient UAV-Assisted NOMA and OMA Data Transmission Utilizing Wide Elliptical Beam

In this work, we present a framework for providing emergency network services to fixed home users in disaster-affected areas through hovering rotary-wing unmanned aerial vehicle (UAV) and minimal terrestrial communication infrastructure. In this regard, we consider that a fifth-generation (5G) next-generation node B (gNB) remains operational (or temporarily deployed) after the disaster, and users outside the gNB’s service area are served by a UAV providing emergency network services. Pertaining to resource constraints in rural areas for establishing post-disaster communication, we propose an optimization framework to maximize the gNB coverage radius considering the 5G rural macro (RMa) propagation scenario. Next, incorporating the air-to-ground (ATG) channel model, we propose non-linear programming (NLP)-based optimization frameworks for UAV-assisted non-orthogonal multiple access (NOMA) and orthogonal multiple access (OMA) data transmission schemes, and compute the transmit power and the UAV hovering height satisfying the users’ quality-of-service (QoS) requirements. Thereafter, to serve the users through the UAV, we investigate a framework for designing a wide elliptical beam. Next, we investigate an exhaustive mathematical framework to determine the angular velocity of the rotors, the current consumption by the rotors, and the hovering power consumption of the UAV. We propose a graphical methodology for computing the battery life of the hovering UAV. The simulation results demonstrate that the proposed methodology of UAV-assisted NOMA and OMA transmission, coupled with a wide elliptical beam, considerably reduces the transmit power requirement and significantly enhances the UAV’s battery life compared to the basic (i.e., without beamforming) UAV-assisted NOMA and OMA transmission schemes. Simulations further demonstrate the effectiveness of our proposed framework for varying geometrical shapes, sizes, and user densities compared to the circular beam.