Real-Time Water Quality Monitoring Using Hybrid OCC and LoRa Communications

This paper presents a novel architecture using a hybrid system for real-time water quality monitoring that combines optical camera communications (OCC) and long-range (LoRa) radio frequency technology. The OCC link enables the communication between underwater sensor nodes and high-resolution image sensors typically mounted on aerial vehicles, such as drones or blimps. The LoRa technology in the proposed hybrid system establishes a reliable and energy-efficient communication channel from the aerial devices to the ground station. This work empirically investigates the performance of the water-air OCC uplink under calm and wavy water surface conditions. As a communication link quality metric, the system signal-to-noise ratio is measured considering several detection schemes as the regions of interest (ROI) for comparison. It is illustrated that the system performance is significantly improved by averaging over the value of several pixels produced by the point spread function, compared to simply using a single pixel as the ROI. In air-to-ground communications, LoRa technology is established through simulations. The maximum achievable data rate at different radii without encountering any packet loss during data transmission is evaluated. Moreover, reinforcement learning is leveraged to optimize the transmitted power and system gain, considering the link range and data rate.