Interference-Asymmetric UAV Remote Control Links: Measurements and Performance Evaluation

Abstract: Reliable and secure connectivity is crucial for remote control (RC) and uncrewed aerial vehicles (UAVs) links. A major problem for UAV RC links is that interference sources within the coverage may degrade the link quality. Such interference problems are a higher concern for the UAV than the RC unit on the ground due to the UAV being in line of sight (LoS) with a larger number of interference sources. As a result, lost hybrid automatic repeat request (HARQ) indicators (ACK/NACK) feedback in the uplink (UL, RC to UAV) may degrade the downlink (DL, UAV to RC) throughput. To get physical evidence for our interference asymmetry argument, we first conducted a measurement campaign using a helikite platform at the Main Campus area of NC State University during the 2024 Packapalooza festival. Subsequently, we evaluated the throughput impact of the loss of HARQ indicator feedback caused by UL asymmetry using MATLAB long-term-evolution (LTE) and fifth-generation (5G) toolboxes. Our numerical results confirm that UL interference asymmetry substantially degrades the throughput performance due to the loss of HARQ indicator feedback.