Design, implementation, and functional validation of a short-range LoRa-based underwater monitoring architecture

Abstract

Environmental monitoring in aquatic ecosystems requires communication systems capable of operating under the particular conditions of underwater environments. This work presents the design, implementation, and functional validation of a short-range underwater monitoring system based on LoRa technology for freshwater environments. The developed architecture integrates a submerged sensor node for environmental data acquisition, a communication buoy located at the water surface, and a web platform for real-time data visualization. Communication between the sensor node and the buoy is performed through a LoRa link operating in the 915 MHz ISM band under an underwater-to-overwater (UW2OW) configuration, while data transmission to the cloud is carried out through a 2.4 GHz Wi-Fi connection. Functional validation was conducted in a controlled environment consisting of a swimming pool and in natural freshwater environments represented by two lagoons, considering different node depths and horizontal separation distances. The maximum distance with detectable reception depended on the node depth and the test environment, ranging from 1.2 to 13 m. However, packet loss increased considerably near these limits; therefore, more conservative operational reference distances were established. Operational limitations related to node depth, packet loss, transmission delay, and effective receiver sensitivity were also identified. The results demonstrate the functional feasibility of the proposed architecture for low-dynamic environmental monitoring applications and provide an experimental basis for future improvements to the communication system and deployment mechanisms in aquatic environments.