Striking a Balance Between System Throughput and Energy Efficiency for UAV-IoT Systems

摘要

The proliferation of Internet of Things (IoT) systems provides us a formidable way to monitor a multitude of things by recording field data and delivering it to the faraway controlling center. However, in hostile or inaccessible areas without infrastructure supports, transmission of IoT data is a daunting task due to the limited physical constraints associated with the weak communication unit and tiny battery supply at the ground sensors. A feasible solution to this problem is to use flexible and programmable unmanned aerial vehicles (UAVs) to gather the ground IoT data and then relay it to the end user, forming a UAV-IoT data collection system. Nevertheless, as we reveal in this article, there is a tradeoff between the two performance metrics-system throughput and sensor energy efficiency. Therefore, the data collection for UAV-IoT system should be power-aware, i.e., expending just enough energy to achieve the required system performance. To this end, in this article, by locating the optimal system parameters-the UAV flying speed and altitude, as well as the frame length at the MAC layer, we can strike a balance between the two conflicting metrics, in that, we can maximize the energy efficiency at the ground sensors, while satisfying the required system performance at the same time. In addition, with a cross-layer design, we can adaptively tune the frame length at MAC layer according to the varying UAV flying speed at the PHY layer, thus promptly switching the system between "system-efficient mode" and "energy-efficient mode."