An adaptive equalizer with significantly reduced number of operations

In adaptive equalization, the coefficients of a transversal filter are automatically adjusted according to a minimum mean-square error criterion. The convolution for the filter process and the cross-correlation in the coefficient-adjustment algorithm require a large number of arithmetic operations. This paper describes an equalizer for complex signals in which filtering and coefficient adjustment are performed in the frequency domain employing Winograd´s Fourier transform algorithms. Compared to the time-domain implementation, the number of multiplications is reduced by typically a factor five without increasing the number of additions. A fast initialization algorithm will be presented. In contrast to earlier work, the convergence behavior will be shown for random data signals transmitted over realistic telephone channels.