Novel optimization techniques for underwater wireless optical communication links: using Monte Carlo simulation

The Underwater Communication Link (UCL) is a crucial component of Underwater Wireless Optical Communication (UWOC) systems, requiring optimised design to mitigate the high power attenuation inherent in seawater. To ensure the reliability of an optimal UCL design, it is essential to account for the three primary scattering regimes: forward scattering (FSC), backward scattering (BSC), and isotropic scattering (ISC) in seawater channels. This study introduces a new photon-tracking model based on a discrete equation, facilitating Monte Carlo Simulation (MCS) to evaluate how different scattering regimes influence received photon distribution. Three distinct Scattering Regime Contribution Weight (SRCW) probability sets were employed, each representing different UCL operational configurations dominated by specific scattering regimes. The proposed modeling approach enables a comprehensive assessment of the temporal characteristics of received optical pulses, channel loss, and time spread—ultimately defining the optimal UCL design parameters. The key findings of this study include: (1) Enhancing the FSC regime dominance leads to a quasi-light waveguide effect over link spans and small Fields of View (FOV) < 25°, significantly improving channel performance in Harbor seawater compared to Coastal seawater. (2) A well-designed UCL with a small FOV (<25°) can minimise channel loss and time spread, ensuring high capacity and efficient performance in both Coastal and Harbor seawaters. (3) When BSC and ISC contributions exceed FSC dominance, the received optical pulse undergoes significant temporal broadening, particularly for larger FOV angles (>25°) and extended link spans. (4) The developed novel MCS-based discrete equation provides a simple yet robust model for simulating photon propagation in both homogeneous and inhomogeneous underwater channels. These insights contribute to developing more efficient and reliable UCL designs with military standards by enhancing UWOC system performance over a longer linkspan for a given limited optical power across various underwater environments.