How much feedback is required for interference alignment over K-user time-variant channel?

Interference alignment with limited feedback can achieve the wireless channel´s maximum multiplexing gain with a error-free low-rate channel state information (CSI) feedback channel. Most interference alignment schemes are designed under the assumption of block-fading channel model in which channels remain static for a period but vary independently from block to block. This assumption ignores the temporal correlation of MIMO channels, which can be used to analyze the overhead of CSI feedback. In this paper, we consider the feedback overhead of interference alignment over time-variant MIMO interference channel. Average CSI and precoders feedback bit rates are derived by modeling each quantized CSI as a first-order finite-state Markov chain. The effect of CSI delay caused by periodic feedback is also analyzed. Finally, the analytical results are verified with numerical simulations while the codebooks are designed by modified Lloyd algorithm.