A high accuracy multi-parameter estimation algorithm for underwater acoustic channels

A novel pilot signal is proposed for the Doppler shift and the delay estimation in the underwater acoustic multi-path channel. A single-frequency signal and a Chirp signal are sent with a fixed time interval. The energy focusing character is applied to process the single-frequency signal part of the mixed signal for the Doppler shift, while the Chirp-based character of the fractional Fourier transform (FRFT) is applied to analyze the Chirp part of the mixed signal for the delay. Besides, it´s not necessary to correlate a bank of correlators as the result of the FFT of high resolution on the single-frequency signal part of the mixed signal for Doppler shift estimation, which greatly improves the algorithm efficient. The simulation results show the algorithm effectiveness.