Finite State Machine of the MQTT-SN Protocol for Its Operation Over IEEE 802.15.4 in Linear Topologies

Currently, the Message Queuing Telemetry Transport for Sensor Networks (MQTT - SN) protocol has been implemented in operating systems such as TinyOS and Contiki to operate above the network layer, in sensor nodes with low processing capacity, powered by batteries and operating in various topologies. However, minimizing the processes at the node side is necessary to make the MQTT - SN protocol applicable in wireless sensor networks (WSNs) with large-scale linear structures. This paper presents the development of the MQTT-SN protocol’s finite state machine (FSM) for its operation over IEEE 802.15.4 in linear topologies. For this purpose, an FSM for each of the twelve procedures indicated in the MQTT-SN specification is obtained. Furthermore, each FSM is represented using the specification and description language, and the characteristics of the IEEE 802.15.4 protocol and the sensor node are considered. Through simulation and the exchange of messages between nodes, the operation of the FSMs is verified. Subsequently, implementing the FSMs in WSNs allows for validating the deployment of the MQTT-SN protocol in linear topologies.