Three-dimensional progressive rotated codebook for advanced multi-user MIMO in LTE-A networks

The three dimensional (3D) characteristics of the wireless communication channels have led to a growing interest in the 3D beamforming techniques, where beamformers can be adjusted in the 3D space to exploit more degrees of freedom of the channel. In this work, we propose a 3D Multi-User Multiple Input Multiple Output (MU-MIMO) progressive beamforming scheme. The proposed scheme adopts varying & rotated 3D codebooks over a certain number of the Channel State Information (CSI) periods. It combines the full dimensional beamforming in one process to scan the 3D space, with 62% reduction in the user feedback overhead compared to the standard LTE-A dual codebook. Additionally, the proposed scheme employs dynamic channel progression technique at the eNodeB, to increase the effective precision of the CSI at the transmitter (CSIT). Simulation results show that the proposed scheme achieves significant outperformance over the standard LTE-A dual codebook.