Interference Alignment in Multi-user MIMO Systems

Interference alignment (IA) has been studied extensively as an advanced technology to obtain the maximum degree of freedom (DoF) of multi-user wireless communication systems. This letter provides a brief review of recent works on IA. The most effective approach of IA is to deploy optimal linear transceivers by exploiting spatial characteristics of wireless channels. It is evaluated in measured multi-input multi-output (MIMO) interference channels. The implementation of IA depends on the characteristics of channel state information (CSI) feedback to the transmitters, such as imperfect, noisy, localized, delayed nature, and so on. In this work, we present a review of existing techniques for IA in typical multi-user MIMO systems. Moreover, we also consider some future research issues related to implementation. The study covers IA's feasibility conditions, solution algorithms in MIMO interference channel and MIMO multi-cell networks, with emphasis on the CSI feedback technology which remains as the major challenge of IA.