  Over the last years, novel low-complexity approaches to the equalization of
MIMO channels have gained much attention. Thereby, methods based on lattice
basis reduction are of special interest, as they achieve the optimum diversity
order. In this paper, a tutorial overview on LRA equalization optimized
according to the MMSE criterion is given. It is proven that applying the
zero-forcing BLAST algorithm to a suitably augmented channel matrix (the
inverse of the square root of the correlation matrix of the data symbols times
the noise variance forms its lower part) results in the optimum solution. This
fact is already widely used but lacks a formal proof. It turns out that it is
more important to take the correlations of the data correctly into account than
what type of lattice reduction actually is used.
