Statistical Characterization of the Angle of Arrival in an Underwater Channel Due to Scattering From the Sea Surface Modeled as Sum of Sinusoids

The objective of this work is the statistical characterization of the angle of arrival (AoA) at the receiver due to scattering from a random sea surface. The sea surface is represented using the sum of sinusoids (SoS) and modeled using the JOint North Sea WAve Project (JONSWAP) sea wave spectrum. The random behavior of potential scatterers along the sea surface, surface wave height, and their impact on the distribution of AoA is evaluated. For coherent scattering, initially, the scatterer distribution is computed for a single realization of the SoS, i.e., a sinusoidal surface. The result obtained is averaged to evaluate the characteristics of the ensemble-averaged SoS surface. For incoherent scattering, the acute randomness of the sea surface leads to every point along the SoS surface acting as a potential scatterer. The overall scattering for any given channel state would be an appropriate combination of coherent and incoherent components. A similar effect manifests itself in the distribution of the overall AoA. Further, the impact of factors such as acoustic signal frequency, wind speed, and the underwater (UW) channel geometry on the parameters of the overall AoA has been studied. The AoA model proposed in this work is general and widely applicable.