Active Interference Cancellation (AIC) techniques
for OFDM spectrum sculpting have gained interest over the
last years, and several extensions to the MIMO case have been
recently proposed. However, these designs do not fully exploit the
spatial diversity provided by the multiple transmit antennas, as
canceler allocation is fixed. This paper proposes a more general
mechanism for the allocation of the cancellation subcarriers
across antennas in order to better exploit spatial diversity. In
particular, we present a novel AIC design for cognitive MIMOOFDM
systems, in which transmit antennas compete against each
other for a fixed number of cancellation subcarriers. We show
that this more general allocation approach results in significant
performance improvements with respect to previous designs.