Robust and Accurate Doppler Factor Estimation for Underwater Acoustic Communication via Interference Correlation-Peak Discrimination

Accurate Doppler-factor estimation and effective Doppler compensation are essential for reliable high-data-rate mobile underwater acoustic communication. However, false correlation peaks and missed peak detections can degrade estimation accuracy or lead to estimation failure. To address the above problem, this paper proposes a coarse-to-fine Doppler-factor estimation method that combines replica correlation, periodic-spacing-based false-peak discrimination, and multi-interval refinement. First, the received signal is cross-correlated with a bank of Doppler-scaled replicas of the synchronization waveform to mitigate mismatch and obtain a coarse Doppler estimate. The Doppler-scaled synchronization-header spacing can be acquired based on the coarse estimate, enabling false correlation peaks to be identified and rejected through integer-multiple spacing-consistency tests. Exploiting the inherent integer-multiple structure of the Doppler-scaled synchronization-header spacings, the proposed method then combines the retained pairwise peak intervals using a Gauss–Markov-type weighted least-squares (WLS) estimator to obtain a refined Doppler-factor estimate in closed form. By exploiting the known multi-header timing structure and jointly incorporating multiple interval measurements, the method limits the influence of false correlation peaks and reduces sensitivity to individual peak-position errors, thereby improving the accuracy of Doppler-factor estimation. Numerical comparisons with representative existing Doppler-factor estimation methods demonstrate that the proposed method achieves favorable estimation accuracy over the investigated signal-to-noise-ratio and radial-velocity ranges. Further simulations demonstrate the robustness of the proposed method to noise-induced false correlation peaks. Comparative sea-trial results show that the proposed estimates generally remain close to the navigation-derived reference, providing further evidence of the effectiveness of the proposed method under the tested field conditions.