An initialization strategy for blind adaptive decision feedback equalizers for dual-mode CAP-QAM reception

This paper introduces a blind start-up technique for decision feedback equalizers (DFE) employed in passband domain based on a multichannel whitening approach. A Hilbert transformer (HT) is applied during acquisition, in order to feed the employed whitening filter by a complex-valued signal. After convergence, the tap weights of the feedback filter are rotated in case of quadrature amplitude modulation (QAM) transmission and the structure is switched to the classical DFE architecture. As the obtained coefficient set may not be optimum, the feedback filter (FBF) is favorably fed by soft decisions in order to minimize the probability of ill-convergence.