An efficient fractionally spaced equalizer with low computations for data transmission

A fractionally spaced equalizer structure is presented. This structure is a cascade form that comprises a predictor and a phase-splitting fractionally spaced equalizer (PS-FSE). The function of the predictor is to preequalize the spectrum of the channel output and reduce the eigenvalue spread of the correlation matrix of the data so as to improve the convergence of the PS-FSE. Comparing the new structure to the complex fractionally spaced equalizer (CFSE), the computations are significantly reduced and the convergence remains almost the same. A new sign algorithm which employs a three-level quantizer is introduced to update the filter coefficients for further simplifying the computations. An optimum three-level quantizer is developed through the detailed analysis of the algorithm. The performance of this three-level sign algorithm (TLSA) is almost the same as that of the LMS algorithm. Simulations prove that the new structure together with the TLSA performs satisfactorily and is a good structure for passband equalization