Fast computation of finite-length MIMO MMSE decision feedback equalizers

We present a new fast algorithm for computing multi-input-multi-output (MIMO) minimum mean-square-error decision feedback equalizer (MMSE-DFE) taps. The new algorithm is obtained by identifying the feedforward equalizer solution as a well known expression encountered in fast recursive least squares (RLS) adaptive algorithms, and the feedback equalizer as a convolution of the feedforward equalizer with the channel. The proposed method is less complex, more structured, and more stable in finite precision than known algorithms in the literature, which rely on fast methods for Cholesky decomposition.