Feedback Channel Effect on the Performance of Interference Alignment

Abstract

In this paper, multi-input multi-ouuput (MIMO) with K users system model is considered where interference between users try to minimize by using minimum mean square error (MMSE) based interference alignmnet (IA) that is a linear technique. Each user in the considered system uses the channel state information (CSI) among all transmitters and receivers to generate own precoding and suppressing matrices. Since these matrices are generated according to the CSI between all transmitter-receiver pairs in the system, it is necessary to transmit this information to all transmitters via a feedback channel after estimating CSI at the receiver. However, the estimated CSI by each receiver is required to share with all transmitters including its own transmitter. In this study, it is investigated the effect of number of bits used to quantization of the CSI, the transmission of the CSI over noisy feedback channels, and outdated CSI on the IA performance. According to the results, impairment on the CSI significantly reduces GH performance.