Blind cancellation of intersymbol interference in decision feedback equalizers

High speed data transmission over bandlimited and/or dispersive channels require equalization to remove the intersymbol interference (ISI) between the successive transmitted data. This paper presents the cancellation of intersymbol interferences (ISI) as a criterion for the blind adaptation of decision feedback equalizers (DFE). We show that this criterion is an alternative to the decision directed (DD) algorithm. This paper also proposes to replace the hard limiter in the decision device of the DFE by a soft decision implemented by a hyperbolic tangent function in order to escape from local minima during the initialization of the blind algorithms. As the theoretical investigation of these criteria and algorithms is difficult, we analyse some simple examples to illustrate the interest of the proposed solutions