Linear Combination Codebook Based CSI Feedback Scheme for FD-MIMO Systems

We present an enhanced CSI feedback scheme for FD-MIMO systems based on a linear combination codebook. To reduce codebook search complexity, an efficient codebook search method is also provided. Both capacity-based and system-level performance evaluations of the proposed scheme are conducted and the performance is compared with the Kronecker product codebook based scheme. The proposed linear combination codebook shows significant performance improvement over the Kronecker product codebook with reasonable increase in feedback overhead; thereby shows the potential to reduce the performance gap towards the ideal CSI scheme.