Interference Alignment in Relay-Aided Networks with Imperfect CSIT

In this paper, a relay-aided interference alignment (RIA) strategy was considered based on the benefits offered by relay-based cooperative networks. Along with the benefits offered by cooperative networks, the RIA was shown as a practical solution for a K-user BC network. The relationship between the achievable DoF region of the RIA and the different levels of outdated channel state information (CSI) were derived. The trade-off between the NRIA and RIA were analysed and the specific trade-off region in each outdated CSI assumption was indicated in the numerical results. Through the achievable DoF numerical results, it was recognised that regarding achievable DoF, the RIA outperforms the NRIA in most of the outdated CSI scenarios.