Performance Assessment of Underwater-to-Air Optical Wireless Communication System With the Effect of Solar Noise and Sea Surface Conditions

This study focuses on the performance evaluation of underwater-to-air Optical Wireless Communication (OWC) and data transmission between Autonomous Underwater Vehicles (AUVs) and Autonomous Aerial Vehicles (AAVs). Facing challenges from the harsh marine environment and optical signal attenuation, we utilized Monte Carlo (MC) simulations to comprehensively assess the system performance. Our investigation incorporated crucial elements impacting signal attenuation, including particulate matter, bubbles, rough sea conditions, and solar noise. By integrating the in-situ Inherent Optical Properties (IOPs) data and Hall-Novarini (HN) model for bubble characteristics, we constructed a robust simulation framework. To accurately estimate optical beam fluctuations caused by surface waves, we employed the three-dimensional theoretical ECKV (Elfouhaily, Chapron, Katsaros, and Vandemark) model for the water-air interface layer. The received power calculated for varying wind conditions, with and without bubbles, revealed fluctuations attributed to surface waves' interaction with the optical signal. Moreover, we observed a decrease in received power due to the bubble effects and the water-air interface layer. Solar radiation's significant impact on the transmitted signal, especially at the airborne receivers, was evident through the BER performance analysis. We conducted extensive experiments for measuring the solar radiance and evaluating its influence on the BER performance, particularly noting degradation during zenith sun positions and increased errors in scenarios with higher solar glint. Additionally, our investigation highlighted the adverse effect of sea surface bubbles on received solar power and the findings revealed that the BER performance is significantly reduced in the presence of bubbles rather than the scenarios without bubbles.