Interference Alignment with Analog CSI Feedback

Interference alignment has been used to derive and realize the maximum multiplexing gain of the MIMO interference channel. Interference alignment requires some form of channel state information at the transmitter. This paper proposes analog CSI feedback as an alternative to limited feedback or reciprocity based alignment. We show that the maximum degrees of freedom of the K-user interference channel are preserved with the suggested feedback strategy, and that the mean loss in sum rate incurred by imperfect CSI is bounded by a constant provided that the signal-to-noise ratio is comparable in both forward and reverse channels. Finally, demonstrate the performance of the proposed strategy through simulation.