MMSE Turbo Equalizer with Preprocessor

A modified linear Minimum mean squared error (MMSE) turboequalizer is proposed in this paper. The proposed method introduces amatched filter, which is used to preprocess the received symbolsequence, into the MMSE turbo equalizer. This matched filter canconcentrate the received symbol sequence and, consequently, shorten thelength of the observation vector without any information loss. Thecomplexity of the MMSE turbo equalizer can be reduced, owing to itscubicity in the length of the observation vector. The simulation resultconfirms that our modified MMSE turbo equalizer performs as well as theoriginal MMSE turbo equalizer with much lower complexity. Moreover, themodified algorithm can provide more flexibility in choosing the lengthof the observation vector, and therefore is more suitable for themulti-path channel with large delay spread.