Limited Feedback Beamforming Codebook Design for Dual-Polarized MIMO Channels

Collocated dual-polarized multiple-input multiple-output (MIMO) antenna systems provide a cost-space efficient alternative to current MIMO antenna systems. A limited feedback beamforming technique is proposed for dual-polarized MIMO channels where the receiver has perfect channel knowledge but the transmitter only receives quantized information regarding the channel instantiation. By decomposing the dual-polarized channel into a single polarized and a decoupled dual-polarized channel, the performance distortion metric can be expressed as a weighted sum of two beamforming distortion metrics. The distortion minimization problem is solved in a suboptimal way by locally minimizing each beamforming distortion metric. A concatenated codebook design approach is proposed. The capacity performance is compared with an interpolated codebook adapted to the cross- polar discrimination (XPD) through linear interpolation. From the simulation results, a concatenated codebook outperforms an interpolated codebook given the same number of feedbacks bits.