Base Station Cooperation with Noisy Analog Channel Feedback: A Large System Analysis

Channel State Information (CSI) at the Base Stations (BSs) can significantly increase the spectral efficiency in single and multi-cell broadcast channels. Assuming the users learn their direct and interfering channels, they can feed back this information to the BSs over the uplink. The BSs then form channel estimates which they use to design their transmission scheme. Clearly, the quality of these estimates affects system performance. In this paper, the authors study limited feedback in a two-cell MIMO broadcast channel. For a fast transfer of CSI, they consider the analog feedback scheme where the users send their unquantized and uncoded CSI over the uplink channels.