  Cellular connectivity to low altitude unmanned aerial vehicles (UAVs) has
received significant interest recently which has led to a 3GPP study on
enhanced LTE support for connected UAVs in Release 15. The objective of the
study is to investigate the capability of long-term evolution (LTE) networks
for providing connectivity to UAVs. In this article, we provide an overview of
the key findings of the 3GPP Release-15 study-item phase. We first introduce
UAV connectivity requirements and performance evaluation scenarios defined in
the study. We then discuss radio channel models and the key identified
challenges of using LTE networks to provide connectivity to UAVs. We summarize
potential solutions to address the challenges including interference detection
and mitigation techniques, mobility enhancements, and UAV identification.
Finally, we also shed light on the key features standardized during the
Release-15 work-item phase.
