Evaluation of LoRaWAN Class B efficiency for downlink traffic

The LoRaWAN technology is today the object of great interest in the Internet of Things context. It defines a simple network architecture offering a wide-area wireless coverage for low rate IoT applications with low power consumption for devices. The LoRaWan class A is designed for sensor networks with a focus on the uplink. LoRaWan defines an optional MAC operation, Class B, that provides the network server with the opportunities to initiate a downlink, which can be a real solution for actuators focus network. Today, Performances of Class B are not quantified and compared to default LoRaWAN class. In this paper, we propose an evaluation of Class B performance. We offer a set of realistic evaluation scenarios based on an NS-3 simulation module that we have developed for this purpose. Results show that Class B reduces the delivery delay of downlink traffic in comparison to Class A. Class B operation significantly reduces the percentage of packet loss for downlink traffic even in congested contexts. We conclude that a trade off should be made between having low access delay or packet loss. Both the NS-3 module and data are released as an open-source to the research community.