Abstract
Sudden user concentration in cellular hotspot environments can significantly degrade the quality of service (QoS) due to the limited capacity of conventional ground base stations (BSs). Although unmanned aerial vehicles (UAVs) equipped with base station functionalities have recently emerged as a promising solution for temporary capacity enhancement, most existing studies assume that UAVs continuously provide services while hovering in the air. Such an approach suffers from severe energy consumption and limited service duration because of the high propulsion power required for hovering.
This paper proposes an energy-efficient dynamic cell capacity expansion scheme based on temporary UAV landing pads. The proposed approach divides a macrocell into multiple UAV sub-cells and deploys temporary landing pads at the center of each sub-cell. When a hotspot event occurs, a UAV equipped with a small base station or repeater function is dispatched to the corresponding landing pad and provides wireless services in a landed state. Since the UAV consumes propulsion energy only during movement and significantly reduces energy consumption during service provision, the proposed scheme substantially extends the service duration of UAV-assisted communications.
Performance evaluations considering UAV battery constraints demonstrate that the proposed landed UAV-BS scheme achieves approximately 87.7% energy savings and extends the UAV service duration by approximately 8.8 times compared with the conventional hovering UAV-BS scheme. Moreover, the proposed approach effectively reduces the blocking rate and maintains higher average throughput during prolonged hotspot situations.