Combined blind equalization and turbo decoding

We describe parallel concatenated codes for communication in the presence of intersymbol interference (ISI). Two iterative decoder structures which combine channel equalization and turbo decoding are presented. The first one combines the trellis representing each one of the constituent encoders with the ISI trellis and performs slightly better that the second structure, which treats the ISI as another constituent decoder. We show that for both methods it is possible to perform the equalization blindly, since the parameters of the channel can be estimated jointly with the combined turbo decoding/equalization algorithm. These methods involve little or no sacrifice in performance relative to the case where the channel taps are known by the receiver.