Underwater communication systems mostly use acoustic signals relayed from a buoy into the water. This approach avoids the high radio attenuation in the water but is limited to the narrow bandwidth of acoustic signals. Optical wireless communication (OWC) has emerged as a promising technology for high-speed underwater networking applications, including global climate monitoring, military operations, and marine biology research. Leveraging the unlicensed optical spectrum enables high data transmission rate. However, this approach faces challenges from absorption, scattering, and turbulence, particularly at the air-to-water (A2W) interface. The dynamic nature of water surfaces causes significant disruptions, compromising the stability and reliability of the end-to-end communication link. This study investigates the impact of water surface variations on the signal-to-noise ratio (SNR) and bit error rate (BER) at the underwater receiver in an A2W OWC channel when the transmitter is mounted on an unmanned aerial vehicle (UAV). A Monte Carlo–based ray propagation framework is adopted to model stochastic scattering effects, and the system performance is evaluated for two different configurations: a small-aperture receiver with lower transmit power and a large-aperture receiver with higher transmit power. We propose a movement optimization framework for the UAV. By dynamically adjusting its position, the UAV can compensate for signal degradation caused by variations in the water surface. We develop and evaluate three movement optimization strategies, tailored for performance, reliability, and value, and visualize the resulting UAV motion using streamplots. Furthermore, we analyze the influence of water surface and system parameters, such as water surface steepness and receiver depth, on different metrics of the UAV movement optimizations. Additionally, we analyze the overall SNR and BER performance by comparing these different optimization approaches. The findings demonstrate that adaptive UAV positioning significantly enhances communication performance, even in the presence of highly dynamic water surfaces.

The field of underwater optical wireless communication (UOWC) has garnered significant attention due to its potential applications in global climate monitoring, military operations, and marine biology research. UOWC offers several advantages, including higher transmission data rates due to increased bandwidth utilization in unlicensed spectrum bands. However, it also faces challenges such as absorption, scattering, and turbulence, especially when dealing with the air-to-water (A2W) interface, which can be random and disruptive. This study involves simulations that demonstrate how a dynamic water surface disrupts the optical wireless communication channel between air and water in terms of received signal intensity. To address this issue, we explore the feasibility and advantages of optimizing the movements of an unmanned aerial vehicle (UAV) with an optical transmitter to counteract the interference caused by water surface waves. By simulating three optimized UAV movement strategies customized for value, reliability, and performance across both intermediate and deep water scenarios, this study demonstrates their effectiveness in achieving improved communication, even in the presence of a disruptive water surface.