Blind equalization of digital communication channels using high-order moments

The authors describe algorithms for blind equalization of digital communication channels of the quadrature-amplitude-modulation (QAM) type. These algorithms are based on the fourth-order statistical moments of the received data sequence. The first of the two is a linear least-squares-type algorithm. The second algorithm is of the nonlinear least-squares-type. The algorithms use the fourth-order statistical moments of the symbol sequence to explicitly estimate the channel impulse response. The estimated impulse response is used, in turn, to construct a linear mean-square error equalizer. The performance of this equalizer is not optimal in any sense, but it is adequate for channels with mild intersymbol interference or when the number of data points available for estimating the channel response is very large