Unveiling Low‑Altitude 5G Performance: Linking Key Influencing Factors with UAV Flight Parameters

Although 5G is widely regarded as a key technology for unmanned aerial vehicle (UAV) cellular communications, its practical performance in low-altitude scenarios remains insufficiently understood. To address this, we conduct large-scale flight measurements over commercial 5G networks and build a cross-layer dataset to compare communication performance between low-altitude and ground. By jointly analyzing 5G configurations, link-layer parameters, and end-to-end metrics, we identify four key factors that significantly affect low-altitude performance: spatial layers, modulation order, handovers, and resource block allocation. Controlled measurements reveal the coupling between UAV flight parameters and these factors. We also discover that network mechanisms optimized for ground scenarios exhibit mismatches in low-altitude environments. For example, we observe a "pseudo-successful handover" phenomenon that rarely appears on the ground yet becomes an important source of unreliable connectivity. These findings provide empirical evidence and insights for improving the reliability of cellular-connected UAVs.