A Flexible Load Balancing Scheme in Multi-UAV-Enabled Wireless Networks

Unmanned aerial vehicles (UAVs) equipped with communication modules can act as mobile base stations. In this paper, we focus on load balancing in multi-UAV-enabled wireless networks, where UAVs serve ground user equipments (UEs) with time division multiple access (TDMA). The UEs have spatiotemporal heterogeneous requests to transfer data which need to be fulfilled in time, the unfinished part called unfinished user request. To improve the quality of service (QoS) and promote the overall system performance, we exploit the flexibility of UAVs to propose a flexible and efficient multi-UAV-enabled load balancing (MULB) scheme. Taking the load balancing effect into consideration, the network optimization problem is formulated as minimizing the maximum unfinished user request by jointly optimizing user association, UAV trajectory, and time slot allocation. Due to integer constraints and non-convexity, we exploit block coordinate descent (BCD) and successive convex approximation to solve it efficiently. Simulation results show that our proposed MULB scheme outperforms existing multi-UAV scheduling schemes in terms of not only the load balancing ability but also the overall system throughput.

I. Introduction

Unmanned aerial vehicles (UAVs) have emerged as pivotal facilities in revolutionizing wireless communication. UAVs equipped with communication modules can function as aerial base stations or relay nodes due to their flexibility and wide coverage. As highlighted by [1], UAVs have proven instrumental in disaster management, providing rapid and reliable network coverage in remote and disaster-stricken areas. Furthermore, the work of [2] emphasized the deployment of UAV-based wireless relays to enhance network performance and capacity in congested urban environments. The resource allocation [3] and communication security [4] have also been extensively studied in UAV-enabled wireless networks.