An MQTT-SN-Based protocol for QoS adaptation in wireless sensor networks

Abstract

The Internet of Things (IoT) remains a concept that is being increased in the last few years. The principal idea is to connect smart devices through a network solution. In the next few years, IoT will be present in everyday objects, in people’s life, almost everything will communicate through the Internet. The economic impact of IoT solution is expected to be, annually, billions of dollars. To provide data exchange from smart devices, some protocols are being used. The Message Queuing Telemetry Transport (MQTT) is one of the most common application protocols for IoT and Machine-to-Machine (M2M) communications. The MQTT implements the paradigm publish/subscribe that provides three Quality of Service (QoS) to ensure message exchange between the devices. However, MQTT protocol is developed over TCP stack and implements the TCP protocol to communicate. There is a version of MQTT for Sensor Network (SN), named of MQTT-SN, developed specially for exchanging messages in Wireless Sensors Networks (WSNs). As many smart devices will be connected on the same WSN, the network can be overloaded and the links may become unstable. This study presents a method to optimize the exchange messages and to increase message delivery during a communication process, between a publisher and a broker or between a publisher and the middleware, implementing the MQTT-SN protocol. The QoS Dynamic Adaptation Method (DAM) for sensor networks was developed on the publisher side. It was focused to select the best Quality of Service between the three QoS levels implemented in the MQTT-SN protocol, based on network latency. The QoS DAM showed good performance in wireless networks, kept message delivery during the communication process, and it showed an impressive performance when compared with the normal QoS implemented in the MQTT-SN protocol.