Institute of Electrical & Electronic Engineers
In this paper, the authors apply the concepts of network Multiple-Input-Multiple-Output (MIMO) to small cell networks. To do so, the issue of imperfect Channel State Information (CSI) at the transmitter is considered when frequency-division duplexing is used, for which the feedback channel is limited. They first introduce a regret based learning approach to optimize the transmit beamforming parameters for the cases when the feedback channel is temporarily unavailable during deep fades. They then propose a coalition formation game model to cluster the small cell base stations so that they can perform cluster-wise joint beamforming.