3D Beamforming: Performance Improvement for Cellular Networks

The beam pattern of a mobile communication base station has significant impact on the performance of a cellular network. 3D beamforming combines the horizontal beam pattern adaptation, as applied for beamforming and MIMO schemes, with vertical antenna pattern adaptation. The recent availability of new flexible antenna techniques enables a fully dynamic antenna pattern adaptation per resource block and per UE, and makes 3D beamforming practically feasible. This paper describes the basic principles of 3D beamforming, including the impact of downtilt adaptation on the physical layer and the potential of combination with beam coordination involving also the MAC layer.For the investigations a geometric pointing of the vertical main lobe of the beam pattern towards the UE is assumed. Different realization options and system simulation results are discussed. Further, Ball Labs' efforts on field trials with vertical beam steering are presented. Using state of the art LTE-like wireless systems including the lightRadioTM antenna array, these trials in the Stuttgart testbed verified the basic predicted properties and potential advantages of 3D beamforming.