Unitary precoder design for MIMO spatial multiplexing systems with limited feedback

This paper studies limited feedback unitary precoding for MIMO spatial multiplexing systems with QR-SIC receiver and equal power allocation. An optimal codebook design criterion, which can design the optimal codebooks for various fading and spatial correlated channels with arbitrary antenna configurations, is proposed. However, due to the fact that the closed-form of the probability density function (p.d.f.) of the optimal precoding matrix is hard to obtain, the optimal codebook design criterion is difficult to be applied to the practical systems. Thus, a suboptimal codebook design criterion is given, which can be implemented in practice and is also applicable to any scenario. Sequentially, an iterative codebook design algorithm that converges to an optimum codebook is given. Simulation results demonstrate that the proposed scheme achieves better performance than the 3GPP R10 LTE-A codebooks.