  This article explores the use of network-connected unmanned aerial vehicle
(UAV) communications as a compelling solution to achieve high-rate information
transmission and support ultra-reliable UAV remote command and control. We
first discuss the use cases of UAVs and the resulting communication
requirements, accompanied with a flexible architecture for network-connected
UAV communications. Then, the signal transmission and interference
characteristics are theoretically analyzed, and subsequently we highlight the
design and optimization considerations, including antenna design,
non-orthogonal multiple access communications, as well as network selection and
association optimization. Finally, case studies are provided to show the
feasibility of network-connected UAV communications.
