On Blind Adaptive Decision Feedback Equalization for Block QAM Signals

Abstract

A two-phase decision feedback equalizer (DFE) has been proposed for block QAM signals. This equalizer operates initially in blind mode, and then switches to a decision feedback mode once the error level in the equalizer output is determined to be low enough for successful equalization. In this work an automatic condition for switching between these two modes is introduced, which is based on a threshold test of a simple easily computed measure called the 'block average variance'. The blind CMA + AMA equalizer is used to initialize the DFE scheme, and performance evaluation results are presented for a random channel. Performance is evaluated using average symbol error rate (SER). Application of this equalizer to the case of a SIMO channel is discussed.