Doppler Frequency Shift Estimation Method for Orthogonal Frequency Division Multiplexing Underwater Acoustic Communication Based on Data Sample Variance

To overcome disadvantages of Orthogonal Frequency Division Multiplexing(OFDM) underwater acoustic mobile communication, a data variance-based Doppler frequency shift estimation method is proposed to estimate the time-varying Doppler shifts. The estimated channel response of previous OFDM symbol is utilized to recover the valid data sequence and its frequency-domain diversity. The variance of the ratio of data sequence and diversity copy are calculated under different Doppler compensation factors. Then the correct Doppler frequency shift factor is achieved by seeking the minimum of the variance. Sparse Bayesian learning and decision feedback channel estimation algorithm are used for calculating the revised channel frequency-domain response. The channel response is propagated to the follow-up symbol to track the time-varying Doppler shifts. The feasibility and superiority of the proposed method are verified by simulation. The sea trail demonstrates that the proposed algorithm can effectively estimate the Doppler shifts in underwater acoustic OFDM mobile communication for Unmanned Underwater Vehicle.