Best-Effort Interference Alignment in OFDM Systems with Finite SNR

Interference alignment has emerged as new tool for achieving high capacity in multi-user and multi-channel wireless interference channels. Based on maximizing a degree of freedom (DOF) metric defined for asymptotic signal to noise ratio (SNR), interference alignment encounters limitations in practical applications because of limited SNR. In addition, perfect interference alignment requires strict antenna-user number condition which may not always hold true as user number increases. In this work, we address these two practical issues in interference alignment. We propose a new definition of interference alignment metric designed to assess the effectiveness of non-ideal interference alignment. We apply the new interference alignment metric to investigate the "best effort" interference alignment in multi-user OFDM systems with limited SNR and limited dimension (subcarriers).