Performance Comparison of Doppler Scale Estimation Methods for Underwater Acoustic OFDM
Doppler scale estimation is one critical step needed by the re-sampling operation in acoustic communication receivers. In this paper, the authors compare different Doppler scale estimation methods using either Cyclic-Prefixed (CP) or Zero-Padded (ZP) Orthogonal Frequency Division-Multiplexing (OFDM) waveforms. For a CP-OFDM preamble, a self-correlation method allows for blind Doppler scale estimation based on an embedded repetition structure while a cross-correlation method is available with the knowledge of the waveform. For each received ZP-OFDM block, the existence of null subcarriers allows for blind Doppler scale estimation. In addition, a pilot-aided method and a decision-aided method are applicable based on cross-correlation with templates constructed from symbols on pilot subcarriers only and from symbols on all subcarriers after data decoding, respectively.