An Interdisciplinary Approach to Optimal Communication and Flight Operation of High-Altitude Long-Endurance Platforms

Aerial communication platforms, stratospheric high-altitude platform stations (HAPS), have the potential to provide/catalyze advanced mobile wireless communication services with its ubiquitous connectivity and ultra-wide coverage radius. Recently, HAPS has gained immense popularity - achieved primarily through self-sufficient energy systems - to render long-endurance characteristics. The photo-voltaic cells mounted on the aircraft harvest solar energy during the day, which can be partially used for communication and station-keeping, whereas, the excess is stored in the rechargeable batteries for the night time operation. We carry out an adroit power budgeting to ascertain if the available solar power can simultaneously and efficiently self-sustain the requisite propulsion and communication power expense. We further propose an energy optimum trajectory for station-keeping flight and non-orthogonal multiple access (NOMA) for multi-cell users, which are served by the directional beams from HAPS communication systems. We design optimal power allocation for downlink (DL) NOMA users along with the ideal position and speed of flight with the aim to maximize sum data rate during the day and minimize power expenditure during the night, while ensuring quality of service. Our findings reveal the significance of joint design of communication and aerodynamic parameters for optimum energy utilization and resource allocation.