Superimposed pilots aided estimation of phase varying channels for underwater acoustic communication

A channel estimation methodology that exploits superimposed pilot sequences for underwater acoustic communication is proposed and evaluated. The proposed scheme first estimates the time-varying channel from the received signal which includes the known superimposed pilot sequence. In a later stage fits the channel response in then fitted to a parametric model that characterizes each channel tap through linear phase progression. In order to evaluate the performance of the proposed scheme, measured channel responses are utilized. Simulation results indicate that the proposed scheme improve upon conventional schemes, particularly in the low signal-to-noise ratio region.