CSI-RS design for 3D MIMO in future LTE-Advanced

Three-dimensional (3D) MIMO is a promising enhancement of MIMO technology to improve system capacity by exploiting the spatial characteristics in both azimuth dimension and elevation dimension. As one of the key aspects in practical systems, the channel state information-reference signal (CSI-RS) design specific to future LTE-Advanced are discussed, and a precoding scheme of CSI-RS considering elevation beamforming is proposed. It is shown that the proposed scheme has the advantages of better performance, small standardization efforts due to its reusability of existing codebook and CSI-RS configurations, and transparency to the legacy UEs.