In the field of Underwater Acoustic (UWA) Communication Orthogonal frequency division multiplexing (OFDM) has drawn wide attention for its high transmission rate and high spectrum efficiency. In the challenging UWA communication channels, OFDM system is tremendously affected by severe multi-path and Doppler effect. In order to transfer data from deep sea AUV (Autonomous Underwater Vehicle) to AUV/surface mother ship this paper describes a new Doppler compensation algorithm of underwater acoustic OFDM communication system. 2 steps Beta (Shrink-expansion) Detection factor, Peak shape cross correlation method and Linear phase error estimation by LS (Least Square) method has been explained in this algorithm. 2 times resample and de-rotation processing is occupied to estimate the initial sending FFT window. Mathematically less complex LS techniques estimate the suitable phase error. Cross-correlation method estimates foremost correlation peak of the cross- correlation among received signal and transmitted signal. Simulation results illustrates the maximum receiver velocity is nearly 4 m/s. Our system exploited 8 kHz Bandwidth (16 kHz to 24 kHz) OFDM channel and subcarrier spacing of 50 Hz.
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