Improving the Energy Efficiency of a LoRaWAN by a UAVbased Gateway The Internet of Things (IoT) devices and applications are spreading all over around us to become the cardiovascular infrastructure for the data of the cyberphysical systems of the future. The implementation of a reliable collection of telemetry data within various application domains, including medicine, safety, and security, industry, smart cities, or environmental monitoring, to name just a few, is among the major challenges still to be solved. Importantly, many of the use cases imply a huge geographic area span or operation in remote areas with limited infrastructure availability and poor reachability. To address these scenarios in this paper, we propose a combination of the two technologies the Low Power Wide Area Network (LPWAN) and the Unmanned Aerial Vehicles (UAVs). Specifically, we study the energy utility and the communication performance of introducing a UAVbased GW into an LPWAN based on the LoRaWAN technology. The results of our simulations show that a UAVbased GW enables to reduce the mean energy consumption for communication in the network by up to 59%. Depending on the UAV speed, the communication performance in terms of the packet delivery ratio can either increase or decrease by several percentage points.

On Spatial Diversity for LoRaWAN: Experimental Evaluation of Performance of a DualGateway Network With and Without Downlink The Low Power Wide Area Networks (LPWANs) is today seen as one of the key connectivity enablers for the massive InternetofThings (IoT) applications. In this paper, we experimentally study the performance of a LoRaWAN network composed of multiple end devices and two independently operating gateways (GW) for the case of uplinkonly and uplink downlink traffic. Our results demonstrate that even though the spatial diversity due to the use of multiple GWs improves the performance of the network for the packet error rate, it still does not guarantee low packet loss under heavy uplink network traffic. Nonetheless, when the downlink traffic is present, a second GW operating in the uplinkonly mode can dramatically increase the uplink packets delivery rate in the network. Therefore, we consider that spatial decoupling of receiver and transmitters, or addition of uplinkonly GWs may become an efficient way to improve the performance of LoRaWAN networks with downlink traffic. Even though the limited laboratory environment might have affected the results of our measurements, we expect that many of the observed trends will also stand for the reallife LoRaWAN deployments. For this reason, the presented results might be interesting both for analysts and practitioners working in the field.