  In this paper, we propose low complexity opportunistic methods for
interference alignment in $K$-transmitter MIMO interference channels by
exploiting multiuser diversity. We do not assume availability of channel state
information (CSI) at the transmitters. Receivers are required to feed back
analog values indicating the extent to which the received interference
subspaces are aligned. The proposed opportunistic interference alignment (OIA)
achieves sum-rate comparable to conventional OIA schemes but with a
significantly reduced computational complexity.
