2D-AOA Estimation and Tilt Angle Adaptation for 3D Beamforming Interference Reduction in Massive MIMO

This paper proposes a new method based on a 2D Angle of Arrival (2D-AOA) estimation that employs 3D beamforming to eliminate the effect of interference in a Massive MIMO (M-MIMO) system. The interferences are the results of pilot contamination and spatial overlapping from nearby users. High resolution Azimuth and Elevation angles of the detected signals from Uniform Rectangular Array (URA) are used to separate the desired signal from the interfering ones without causing any change in the pilot construction of training signals. Additionally, tilt angle adaptation is employed at the base station to maximize the spectral efficiency of multi-cell M-MIMO. The performance of the proposed method is evaluated and compared with that of the conventional methods of 2D beamforming in terms of achievable sum rate. Results of the simulation demonstrate that the 3D beamforming achieved a 55% sum rate gain due to the elimination of both pilot contamination and spatial overlapping in comparison to the 24% sum rate gain achieved via the 2D beamforming method which only eliminate pilot contamination. This shows the potential of the proposed method in eliminating a large proportion of cell interference.