Effect of 3-dimensional beamforming on full dimension MIMO in LTE-Advanced

Large-scale antenna system has attracted significant attention in the wireless industry and academia area in the past few years as a candidate technology for the next evolution towards beyond 4th generation cellular systems. It can utilize a large number of antennas placed in a two-dimensional (2-D) antenna array panel for realizing spatially separated transmission links to a large number of mobile stations (MSs). The arrangement of these antennas on a 2-dimensional active antenna array allows the extension of spatial separation to the vertical domain as well as the traditional horizontal domain with the user-specific 3-dimensional beamforming. Utilizing such spatial separation capability, a base station (BS) can realize spatial multiplexing to a large number of MSs under 3-dimensionally spread channel environment. In this paper, we study the effect of user-specifica beamforming using both veritcal and horizontal direction on the large-scale antenna evolution of LTE system: Full Dimension MIMO. Evaluation results with various antenna configurations show while FD-MIMO provides significant improvement over conventional LTE systems, the size and spacing of active array within 2-D antenna structure need to be carefully selected to maximize FD-MIMO´s full potentials in different cell deployments.