A survey on UAV-assisted wireless communications: Recent advances and future trends

Abstract

Due to their characteristics of mobility, flexibility and adaptive altitude, unmanned aerial vehicles (UAVs), also known as drones, have immense potential applications in wireless systems. In particular, UAVs can operate as flying mobile terminals within a cellular network, and such cellular-connected UAVs have enabled several applications ranging from real-time video streaming to item delivery. Furthermore, the deployment of UAVs in wireless networks as flying base stations (BSs), servers or relays is expected to enhance network performance in terms of coverage, capacity, reliability and energy-efficiency. In this paper, a comprehensive tutorial on the potential applications and benefits of UAVs is presented. Specifically, UAVs as aerial BSs collecting data from ground sensors, transmitting power to energy-constrained devices and broadcasting information to ground users are explored along with representative design objectives. Then, UAVs as relay nodes for coverage extension, pathloss compensation and interference mitigation are surveyed comprehensively. Besides, UAVs as mobile servers performing edge computing for ground users are introduced, and various aerial offloading modes are reviewed thoroughly. Furthermore, radio and computation resource optimization, as well as mathematical tools and developed algorithms, are described in UAV-assisted communicating, relaying, and computing systems. Finally, open problems and potential research directions pertaining UAV-assisted communications are presented. In a nutshell, this tutorial provides key guidelines on how to design, analyze and optimize UAV-assisted wireless communication systems.