Experimental Validation of a Multi-hop Underwater LoRa RF Network

Underwater wireless communication is difficult because radio signals are strongly affected by the water environment. Acoustic and optical technologies are commonly used, but they have several limitations. Recently, radio-frequency electromagnetic communication based on LoRa modulation has attracted interest as a possible solution for short-range and low-power underwater applications. This thesis studies the feasibility and performance of a multi-hop underwater LoRa communication system through experimental measurements. A multi-hop experimental setup was built using Arduino MKR WAN 1310 boards with external antennas, SD-card memory shields, and battery power supplies. Custom firmware was developed to enable direct LoRa communication with packet forwarding between nodes, configurable transmission parameters, and synchronized test execution. The experiments were first validated in laboratory conditions and then carried out in a river environment. Different LoRa configurations were tested by changing the spreading factor and coding rate. The system performance was evaluated using metrics such as packet delivery ratio, received signal strength indicator (RSSI), and signal-to-noise ratio (SNR). The results show how the choice of LoRa parameters influences communication reliability and reception quality in a multi-hop underwater scenario. In addition, practical implementation issues observed during the experiments, including a reliability problem in SD-card data logging and the adopted solution, are described. The findings provide useful insights into the potential and limitations of using LoRa technology for underwater multi-hop communication in real environments.