Field Trial Evaluation of 3D Beamforming in a Multicell Scenario

3D beamforming is a technique which allows the adaptation of the base station (BS) antenna downtilt per user equipment (UE). The selection of the appropriate downtilt depends on the propagation properties of the environment. This paper investigates the optimum downtilt angle in a typical nonline-of-sight (NLOS) urban outdoor environment. Therefore measurements with variable downtilt have been conducted in a real deployment scenario in Dresden. For different measurement locations the downtilts needed for maximum receive power at the UE are compared to predictions based on different existing propagation models for the vertical dimension of the radio channel. Since the testbed allowed also multi-cell operation, the benefits of downtilt adaptation on the signal-to-interference ratio (SIR) could be verified. Keywords—3D beamforming; downtilt adaptation; beam coordination; field measurements, vertical channel model; multicell, SIR