Evaluation of Beat Noise and Turbulence-Induced Impairments on SAC OCDMA-Based UWOC Systems

This paper investigates the impact of beat noise and turbulence on spectral amplitude coding optical code division multiple access (SAC-OCDMA) systems operating in underwater wireless optical channels. The turbulence, arising from salinity variations and air bubbles, is modeled using the Weibull distribution. Three multi-laser source configurations are examined: a centralized shared multi-laser source, a uniformly distributed central frequency multi-laser source, and a precisely controlled central frequency multi-laser source. The results demonstrate that, although both beat noise and turbulence affect the detected optical intensity, beat noise is the dominant performance-limiting factor. Furthermore, error-free transmission is achievable under weak turbulence conditions only when a precisely controlled multi-laser source is employed, with a central frequency precision of 3 GHz at a data rate of 1.25 Gbps.