Widely linear MMSE equalizer for MIMO linear time-dispersive channel

The paper deals with transmission over multiple-input/multiple-output (MIMO) communication systems where, due to the large demand of high bit-rate telecommunication services, is required to take into account the time-dispersion of the channel. Recently, widely linear processing, which can be considered as a generalization of linear processing, has been proposed for single-input/single-output (SISO) and MIMO zero-memory equalizer. In this paper, widely linear processing has been extended to the general case of minimum mean square error (MMSE) equalizer for both finite impulse response (FIR) and recursive structures. Simulation results (with reference to recursive structure) show that the proposed equalizer significantly outperforms the linear MMSE equalizer and decision feedback one in operative conditions of practical interest where the conditions of joint circularity of input and output signals are not satisfied (e.g., DS/WCDMA employing BPSK scheme).