On Data Collection in SIC-Capable Space–Air–Ground Integrated IoT Networks

This article considers routing and uplinks scheduling in space–air–ground integrated networks. Specifically, it considers a successive interference cancellation-capable unmanned aerial vehicle (UAV) that collects data from ground devices operating in an Internet of Things network. Its objective is to maximize the minimum flow rate to a terrestrial gateway over a fixed time horizon. It outlines a mixed integer linear program (MILP) to optimize in each time slot: the routing from the UAV to the gateway, the set of links from ground devices to the UAV, and the flow rate over links. It also proposes a novel algorithm, called iterative flow and path reservation (IFPR), for use by the UAV to select paths. Further, IFPR uses two methods to schedule communications between ground devices and the UAV. The first method, called simplified MILP (SMILP), aims to maximize the sum rate from ground devices. The second method, called less data schedule first, prioritizes ground devices that have uploaded the least amount of data to the gateway. Numerical results show satellite links help the UAV collects 61% more data from ground devices. Moreover, as compared to the MILP, IFPR collects 23% less data. Further, for both MILP and IFPR, their Jain’s fairness index reaches around one when the number of time slots is sufficiently large. Finally, when IFPR uses SMILP, the gateway collects more data but at the expense of fairness.