  The $2$ user MIMO interference channel with arbitrary antenna configurations
is studied under arbitrary levels of partial CSIT for each of the channels, to
find the degrees of freedom (DoF) achievable by either user while the other
user achieves his full interference-free DoF. The goal is to gain new insights
due to the inclusion of MIMO (multiple antennas at both transmitters and
receivers) into the signal space partitioning schemes associated with partial
CSIT. An interesting idea that emerges from this study is "elevated
multiplexing" where the signals are split into streams and transmitted from
separate antennas at elevated power levels, which allows these signals to be
jointly decoded at one receiver which has fewer spatial dimensions with lower
interference floors, while another receiver is simultaneously able to
separately decode these signals with a higher interference floor but across a
greater number of spatial dimensions. Remarkably, we find that there is a DoF
benefit from increasing the number of antennas at a transmitter even if that
transmitter already has more antennas than its desired receiver and has no
CSIT.
