Multimode Precoding for MIMO Systems: Performance Bounds and Limited Feedback Codebook Design

This correspondence investigates the problem of designing the precoding codebook for limited feedback multiple-input multiple-output (MIMO) systems. We first analyze the asymptotic capacity loss of a suboptimal multimode precoding scheme as compared to optimal waterfilling and show that the suboptimal scheme is sufficient when negligible capacity loss is allowed. This knowledge is then applied to the design of the limited feedback codebook. In the design, the generalized Lloyd algorithm is employed, where the computation of the centroid is formulated as an optimization problem and solved optimally. Numerical results show that the proposed codebook design outperforms the comparable algorithms reported in the literature.