Research On Carrier Phase Recovery Blind Equalization Algorithm For Underwater Acoustic Channel

Inter-symbol interference(ISI) caused by the multipath effect in underwater acoustic channel greatly limits the maximum transmission rate of the underwater acoustic communication(UAC) system and causes a higher bit error rate(BER).At the same time,the phase rotation of the equalizer output signal will lead to the misjudgment during the data coherent demodulation process.Therefore,how to overcome the phase rotation caused by the multi-path channel and eliminate the impact of ISI is a important question to improve the quality of UAC.In this paper,the carrier phase recovery algorithms are analyzed in depth in the following aspects: carrier phase recovery,convergence rate and precision.The main work and invonation of the paper include:(1)The basic theory of carrier phase recovery blind equalization algorithm.is analyzed and two kinds of fast carrier phase recovery algorithm are proposed:fast carrier phase recovery algorithm based on the weight vector initialization(FCRAVWI) and fast iteration carrier phase recovery algorithm(FICRA).FCRAVWI increases the speed of convergence by initializing the weight vector and FICRA uses the super-exponential iteration factor in the iterative process to improve speed.(2)To the characteristic of16QAM signal, a hybrid square contour algorithm(SCA-DD) and a variable step-size adaptive varying modulus square contour algorithm(VAVSCA) are prosed.SCA-DD collects the convergence capacity of SCA and the low residual error of DD.VAVSCA improves the covergence speed by using different step-size in different aeras.(3) A modified SCA based on wavelet transform(WT-MSCA) is proposed.This algorithm improves the accuracy of equalization by deviding the modulus into inphase and quadrature components and improves the convergence speed obviously by using the wavelet transform to reduce the dispersion degree of the equalizer input autocorrelation eigenvalues...