  By means of network densification, ultra dense networks (UDNs) can
efficiently broaden the network coverage and enhance the system throughput. In
parallel, unmanned aerial vehicles (UAVs) communications and networking have
attracted increasing attention recently due to their high agility and numerous
applications. In this article, we present a vision of UAV-supported UDNs.
Firstly, we present four representative scenarios to show the broad
applications of UAV-supported UDNs in communications, caching and energy
transfer. Then, we highlight the efficient power control in UAV-supported UDNs
by discussing the main design considerations and methods in a comprehensive
manner. Furthermore, we demonstrate the performance superiority of
UAV-supported UDNs via case study simulations, compared to traditional fixed
infrastructure based networks. In addition, we discuss the dominating technical
challenges and open issues ahead.
