  It is shown that while the mutual information curves for coded modulation
(CM) and bit interleaved coded modulation (BICM) overlap in the case of a
single input single output channel, the same is not true in multiple input
multiple output (MIMO) channels. A method for mitigating fading in the presence
of multiple transmit antennas, named coordinate interleaving (CI), is presented
as a generalization of component interleaving for a single transmit antenna.
The extent of any advantages of CI over BICM, relative to CM, is analyzed from
a mutual information perspective; the analysis is based on an equivalent
parallel channel model for CI. Several expressions for mutual information in
the presence of CI and multiple transmit and receive antennas are derived.
Results show that CI gives higher mutual information compared to that of BICM
if proper signal mappings are used. Effects like constellation rotation in the
presence of CI are also considered and illustrated; it is shown that
constellation rotation can increase the constrained capacity.
