  Besides being part of the Internet of Things (IoT), drones can play a
relevant role in it as enablers. The 3D mobility of UAVs can be exploited to
improve node localization in IoT networks for, e.g., search and rescue or goods
localization and tracking. One of the widespread IoT communication technologies
is Long Range Wide Area Network (LoRaWAN), which allows achieving long
communication distances with low power. In this work, we present a drone-aided
localization system for LoRa networks in which a UAV is used to improve the
estimation of a node's location initially provided by the network. We
characterize the relevant parameters of the communication system and use them
to develop and test a search algorithm in a realistic simulated scenario. We
then move to the full implementation of a real system in which a drone is
seamlessly integrated into Swisscom's LoRa network. The drone coordinates with
the network with a two-way exchange of information which results in an accurate
and fully autonomous localization system. The results obtained in our field
tests show a ten-fold improvement in localization precision with respect to the
estimation provided by the fixed network. Up to our knowledge, this is the
first time a UAV is successfully integrated in a LoRa network to improve its
localization accuracy.
