Confirmed traffic in LoRaWAN: Pitfalls and countermeasures

LoRaWAN networks are growing in popularity and adoption, mainly thanks to the inexpensive devices, the affordable gateway costs, and the possibility to opt for a private deployment or the use of global network providers. While the main use case for these networks is sensor data collection, the standard also defines confirmed messages, for which downlink transmissions are required. In this paper we show that an incautious use of this feature can bring a sharp decrease in the performance of the network, especially for large scale deployments. Additionally, we present some insights on how certain design choices for downlink communication in LoRaWAN are impairing confirmed traffic usage and propose some solutions to mitigate the issue.