3D Beamforming Technologies and Field Trials in 5G Massive MIMO Systems

In this paper, three-dimensional (3D) beamforming characteristics and applications in fifth generation (5G) mobile communications have been studied by considering the physical structure of array antennas, and the properties of the 3D beam pattern formed by planar, rectangular array antennas. Array beam gains are formulated according to rectangular array antennas. The effect of array antenna configuration on 3D beamforming is studied especially according to the building height. The field trial and measurement results have been presented for single and multiple mobile users. The field trial results show that (1) The total sum rate from all users can be increased multiple times (i.e., 3 to 4 times) as large as that of a single user. When the number of users is larger than 8, the sum rate becomes saturated; (2) Users with uniform angular distribution can achieve larger sum rate than users with centralized distribution due to space separation; (3) The performance of the multi-antenna system is best under static-user conditions, with it dropping considerably for mobile conditions, even by more than 50% due to poor channel state information estimation; (4) In case of 3D beamforming, good coverage performance can be achieved in medium or high buildings.