A simple model for imperfect channel state information and its application for the assessment of Interference Alignment

It has been shown that Interference Alignment (IA) based transmit precoding achieves remarkable performance gains under ideal assumptions of perfect channel state information (CSI) and fully uncorrelated channels. In this work, we have derived a simple model for imperfect CSI to assess the gains of IA using a 3GPP compliant system level simulator. By using our model we have evaluated the performance of IA using two different receiver algorithms based on ideal and practical realizations. We have further compared the performance of IA with two other baseline state of the art coordinated and non-coordinated precoding schemes. Our results show that the gains of IA are very sensitive to CSI imperfections as compared to the other baselines. However, in case of the availability of high SINRs with very slow moving users leading to very large channel coherence time/bandwidth, IA outperforms the other schemes even with imperfect CSI. The results draw important conclusions about the application of IA in practical systems.