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In order to gain a better performance and reduce the computational complexity of the filter design in the underwater acoustic single carrier system,a new Iterative Block DFE (IBDFE)is proposed,which operates iteratively on blocks of the received signal,and fully implements its filtering operations by Discrete Fourier Transforms (DFTs).Two design methods are considered for IBDFE:one is HD-IBDFE,and the other is SD-IBDFE.In this paper,the first one is adopted.In this scheme,hard detected data are used as input of the feedback,and filters are designed according to the correlation between detected and transmitted data.In the simulations and experiments,the method of the HD-IBDFE is introduced,and for comparison,the performance of H-DFE is shown,as well as that of ZF,MMSE and Matched-Filter-Bound (MFB).From the results of the simulations on a Rayleigh fading channel,it is easily found that on average,the HD-IBDFE outperforms H-DFE.When the number of iteration is 4,HD-IBDFE outperforms ZF,MMSE and H-DFE by about 11dB,5dB and 0.7dB respectively at BER =10-4.As for MFB,the HD-IBDFE still has a degradation of 1.6 dB.In addition,the experimental results in both experiment pool and shallow water also verify the achievement.The simulation and experiment results indicate that the IBDFE outperforms other equalization schemes.What’s more,it exhibits a reduction of the computational complexity.