Residual degrees of freedom based codebook design for cooperative beamforming

Recently, coordinated multiple point transmission/reception (CoMP) is proposed to overcome the performance degradation due to the inter-cell interference (ICI) in a multi-cell environment. In this paper, we present a multiuser MIMO-BC technique with limited feedback, and propose the novel codebook for cooperative beamforming to reduce the ICI. Based on the proposed codebook, an orthogonal beamforming is performed, which can support N_B - η users simultaneously. The residual η degrees of freedom is used for the ICI mitigation. The numerical results show that the orthogonal beamforming based on the proposed codebook can obtain the η degrees of freedom efficiently without any loss of performance.