Doppler estimation and compensation for underwater acoustic OFDM systems

Underwater acoustic (UWA) channels brings frequency-dependent Doppler shifts. In this paper, we treat the channel as having a common Doppler scaling factor on all propagation paths, and propose a novel approach to mitigating the Doppler effects. First, we used the same sampling interval as the transmitter to the received signal. Secondly, we compare the number of the two sampling points. According to the difference of the number, we can acquire the Doppler scale factor. Then Doppler compensation was finished via resampling. We focus on orthogonal frequency-division multiplexing (OFDM) to transmit signal, and pilot subcarriers are used for channel estimation. The receiver is based on block-by-block processing,it is suitable for fast-varying UWA channels. The method was tested through simulation on computer, and a good property was acquired.