The Effect of Imperfect CSI in a Multi-Cell Multi-User MIMO System

One of the promising candidates for mitigating the inter-cell interference in multi-cell networks is coordinated beamforming (CB), where cells are allowed to cooperate such that the transmission from each cell takes into account the interference it would cause to the users of other cells. In this work, we study the performance of a centralized algorithm which enables beam coordination in multi-cell multi-user multiple-input multiple-output (MIMO) network. The algorithm aims at maximizing the weighted sum rate (WSR) via weighted sum mean squared error (WSMSE) minimization, taking into account the estimation noise of channel state information (CSI). The performance is studied in a seven-cell network and the numerical results show that also with inaccurate CSI, CB outperforms traditional orthogonal access (OA) scheme where the same frequency resources are not reused between cells.