IoT Protocols Comparison for Wireless Sensors Network Applied to Marine Environment Acoustic Monitoring

There is a growing interest to analyze acoustic marine environment. Underwater sounds can indicate the natural marine activity, as well as the influence of human activities in the aquatic ecosystems. Several kinds of electronic devices can be used to monitor the marine sound, but normally these devices work autonomously, without communication with other equipment, which makes difficult the real-time monitoring. In addition, the usual equipment is normally expensive and highly complex. Thus, for the design of wireless sensor network (WSN) applied to marine monitoring, it is important to develop systems with good energy autonomy and efficient data processing and communication. However, it is not well established the best WSN communication protocol for applications in hostile environments. Some protocols used for Internet of Things (IoT) applications have emerged recently as alternative for efficient communication between nodes and gateways. This work presents a comparison between two IoT application protocols: CoAP and MQTT-SN. We have verified that the MQTT-SN protocol has some advantages, such as: its latency is 30% lower compared with CoAP, the power consumption is 10% lower than CoAP, and the traffic flow is 2.15 times larger than CoAP, for an architecture with 40 wireless nodes.