Channel models for underwater acoustic communications

The successful transmission of high-speed digital data through any medium requires a knowledge of the degradations and distortions introduced into the received signal by the medium itself. This knowledge can then be used to design suitable detection schemes, usually based around adaptive equations, to take account of the distortion when detecting data from the received signal. In the case of an underwater communication channel, these degradations are mainly caused by multipath propagation of the transmitted signal energy, which for the realistic cases of turbulent sea conditions, non-homogeneous media and acoustic scattering will be time-varying in nature. It follows that the received signal can suffer severe and rapid amplitude fluctuations (fades) across the bandwidth of the signal. [Continues.]