Modeling and oblique transmission characteristics of an underwater wireless optical communication channel based on ocean depth layering

Underwater wireless optical communication is widely considered in the field of underwater communication due to its high bandwidth and low latency. In a real transmission link, the temperature and salinity of seawater, chlorophyll concentration, and bubble density vary with ocean depth. Therefore, the depth of the optical transmitter in seawater and the tilt angle of the beam will exhibit different beam transmission characteristics. In this paper, an underwater oblique-range layered channel model considering the combined effects of dynamic turbulence, absorption, and scattering is developed based on real data of seawater at different depths measured by the Global Ocean Observing Buoy Argo and the Woods Hole Oceanographic Institution BCO-DMO. The effects of transmission distance, transmitter tilt angle, and transmitter depth on the oblique-range transmission characteristics of the beam in seawater are discussed. The simulation results show that, at the same transmission distance, the beam centroid displacement increases with an increase in transmitter depth only when the transmitter is located above the interior of the thermocline. When the transmitter is located below the interior of the thermocline, the influence of the transmitter tilt angle on the beam centroid displacement decreases. This indicates that at different depths within the interior of the thermocline, the optical beam transmission characteristics exhibit significant variations.