Underwater Wireless Optical Communication: Channel Modeling of Multiple Scattering in Presence of Chlorophyll Concentration Variations

The communication qualities of underwater wireless optical communication systems (UWOC) are severely limited by attenuations caused by absorption and scattering of the seawater. Hence, analyzing the underwater wireless optical channel induced by absorption and scattering is of great practical value for the design and deployment of underwater wireless optical communication systems. Currently, the research on underwater scattering channels typically considers horizontal links, where the absorption and scattering effects in the seawater can been set to constant parameters. However, as for the vertical link, the chlorophyll concentration varies with the depth of seawater, which results in variations of absorption and scattering effects with the increment of link lengths. Consequently, this paper proposes a chlorophyll-induced seawater channel model and analyzes the absorption and scattering effects in the seawater using the Monte Carlo method. The simulation results show that as the increment in the seawater depth will increase the peak of channel impulse response (CIR) and probability density function (PDF), resulting in lower bit error rates (BER) for the UWOC system. Under the same depth and link distance conditions, the performance of the vertical downlink is slightly better than that of the horizontal optical link.