Aperture-Averaged Angle-of-Arrival Fluctuations in Oceanic Turbulence of Arbitrary Strength

In this work, the effects of aperture averaging on reducing the angle-of-arrival (AOA) fluctuations in oceanic turbulence of arbitrary strength are examined. The analytical formulations for the aperture-averaged AOA fluctuation variances of plane and spherical waves are established based on the Rytov and the extended Rytov approximation methods, respectively, for weak and moderate-to-strong turbulence. The numerical results demonstrate how much smaller the AOA variance is for the large receiving aperture than for the point receiver under different turbulence conditions. Furthermore, it is carefully investigated how AOA fluctuation varies in terms of various propagation and oceanic turbulence parameters, such as link length, aperture size, average temperature, and average salinity of seawater. These findings will benefit the design of the underwater communication and imaging systems.