Adaptive Quality of Service Control for MQTT-SN

Internet of Things and wireless sensor networks applications are becoming more and more popular nowadays, supported by new communication technologies and protocols tailored to their specific requirements. This paper focuses on improving the performance of a Wireless Sensor Network operated by the MQTT-SN protocol, one of the most popular publish/subscribe protocols for IoT applications. In particular, we propose a dynamic Quality of Service (QoS) controller for the MQTT-SN protocol, capable of evaluating the status of the underlying network in terms of end-to-end delay and packet error rate, reacting consequently by assigning to a node the best QoS value. We design and implement the QoS controller in a simulated environment based on the ns-3 network emulator and we perform extensive experiments to prove its effectiveness compared to a non-controlled scenario. The reported results show that, by controlling the Quality of Service, it is possible to manage effectively the number of packets successfully received by each device and their average latency, to improve the quality of the communication of each end node.