An enhanced beamforming algorithm for three dimensional MIMO in LTE-advanced networks

Multiple input multiple output (MIMO) system with large number of antennas, referred to as massive MIMO, has drawn increasing attention for it enables very high throughput in LTE-Advanced networks. Massive MIMO arrays are expected to be implemented in a three dimensional (3D) array structure and 3D MIMO is introduced. Antenna propagation was considered only in horizontal domain during the past few years. In this paper, vertical domain of antenna is taken into account and the modeling of 3D channel is investigated. Furthermore, an enhanced dynamic beamforming algorithm is proposed where beamforming vector can be obtained according to both users´ horizontal and vertical directions. Enhanced performance can be obtained by the proposed algorithm compared with conventional 2D beamforming. In addition, the impact of sector radius on spectral efficiency as well as cell coverage is analyzed and the optimal downtilts for different senarios are explored.