Sum rate capacity for orthogonal random beamforming in multi-cell MIMO scenarios

In multiple-antenna broadcast channels, orthogonal random beamforming (ORB) constitutes an effective mean to exploit multi-user diversity (MUD) for its inherent opportunistic attribute. However, most of recent papers just consider the single-cell hypothesis in which case multi-cell interference is completely neglected. In order to conform to the wireless environment in reality, a multi-cell model employing ORB scheme is proposed in this paper. Based on the nonquantized signal to interference plus noise ratio (SINR) feedback model, a closed-form expression of theory limit for sum rate capacity is proposed. The theory limit of single-cell model is proved to be a special case of our proposed model. Furthermore, the fairness of our model in interference limited system can be improved distinctly than that of single-cell model, at the decreasing cost of sum rate capacity. Simulation results show that the proposed model has more rationality and generality compared with single-cell model.