A Geometry-Based Underwater Acoustic Channel Model Allowing for Sloped Ocean Bottom Conditions

This paper proposes a new geometry-based channel model for shallow-water ocean environments, in which the ocean bottom can slope gently down/up. The need for developing such an underwater acoustic (UWA) channel model is driven by the fact that the standard assumption of a flat ocean bottom does not hold in many realistic scenarios. Starting from a geometrical model, we develop a stochastic channel model for wideband single-input single-output vehicle-to-vehicle UWA channels using the ray theory assuming smooth ocean surface and bottom. We investigate the effect of the ocean-bottom slope angle on the distribution of the channel envelope, instantaneous channel capacity, temporal autocorrelation function, frequency correlation function, Doppler power spectral density, and the power delay profile. Theoretical and simulation results show that even a relatively small slope angle influences considerably the statistical properties of UWA channels. The validation of the proposed UWA channel model has been performed by fitting its main characteristic quantities (average delay, delay spread, and coherence bandwidth) to measurement data. In comparison with the conventional UWA channel model, which has been developed on the assumption of a flat ocean bottom, it is shown that the proposed UWA channel model enables the modeling of measured channels with higher precision.