Fundamentals and Performance of the LoRaWAN Downlink: an Experimental Approach

International audienceToday, LoRaWAN networks have reached a major milestone on the Internet of Things application domains thanks to their fascinating characteristics, especially in terms of large coverage and low energy consumption. Several studies have focused on the performance optimization of these networks. Indeed, gateway-centric allocation strategies look for the optimal configuration of the transmission parameters and send them to thousands of end-devices through MAC commands on the downlink. However, most of these allocation strategies are validated either by simulation or mathematical models. In this paper, we discuss the fundamentals and the requirements of the MAC commands transmission on the downlink. Our design allows IoT applications to transmit frames on the downlink hitherto reserved for mac configuration commands, makes easier the implementation of new spreading factor assignment strategies, and provides an experimental framework for Downlink performance analysis. We validated our proposal through an extensive experimental study, demonstrated the limitation of downlink over uplink due to the sensitivity of the end-device receiver, and finally, we studied the impact of traffic load on the downlink performance