UAVs for QoS or Energy Drain? A Study on Energy Reduction Capability of UAV-Assisted Cell Switching Scenarios in 6G

Energy efficiency is a key performance indicator (KPI) in sixth-generation (6G) cellular networks. In fifth-generation (5G) systems, small base station (SBS) on–off switching has been widely adopted to improve this KPI. In 6G networks, envisioned as three-dimensional (3D) architectures, drone base stations (DBSs) can complement SBSs by enhancing energy efficiency during on–off switching while maintaining user quality of service (QoS), particularly when the backhaul energy consumption of base stations is explicitly considered due to its significant contribution to overall infrastructure energy usage. This paper presents a framework to assess the energy-saving capability of such UAV-assisted switching scenarios. An analytical and optimization-based approach is employed to characterize the system behavior and derive thresholds for key parameters, including the number of users, available DBS resources, and service time, under which UAV-assisted on–off switching remains energy-efficient. Simulation results demonstrate that the proposed framework effectively identifies feasible operating regions and provides design insights for future energy-efficient UAV-assisted cell switching in 6G networks.