  Firstly, a reordered description is given for the linear minimum mean square
error (LMMSE)-based iterative soft interference cancellation (ISIC) detection
process for Mutipleinput multiple-output (MIMO) wireless communication systems,
which is based on the equivalent channel matrix. Then the above reordered
description is applied to compare the detection process for LMMSE-ISIC with
that for the hard decision (HD)-based ordered successive interference
cancellation (OSIC) scheme, to draw the conclusion that the former is the
extension of the latter. Finally, the recursive scheme for HD-OSIC with reduced
complexity and memory saving is extended to propose the recursive scheme for
LMMSE-ISIC, where the required computations and memories are reduced by
computing the filtering bias and the estimate from the Hermitian inverse matrix
and the symbol estimate vector, and updating the Hermitian inverse matrix and
the symbol estimate vector efficiently. Assume N transmitters and M (no less
than N) receivers in the MIMO system. Compared to the existing low-complexity
LMMSE-ISIC scheme, the proposed recursive LMMSE-ISIC scheme requires no more
than 1/6 computations and no more than 1/5 memory units.
