Underwater Visible Light Communications, Channel Modeling and System Design

This chapter presents the fundamentals of underwater wireless optical communications (UWOC). It focuses on aquatic channel properties, modeling, and characterization. Upon interaction with the particles in suspension or solution within seawater, a propagating light beam is deviated from its initial direction through the scattering process, and a part of its intensity is absorbed and converted into other forms of energy. Absorption is the irreversible loss of power as light propagates in the medium. Colored dissolved organic matter (CDOMs) increase the absorption rate with a decrease in wavelength; this absorption is more pronounced in the blue and ultraviolet spectral ranges. The propagation of light underwater is typically modeled by the radiative transfer equation (RTE), which involves integrodifferential equations of time and space that characterize a light field traversing a scattering medium. The chapter describes the design of an UWOC for integration into autonomous underwater vehicles (AUVs).