Beamforming Optimization For LTE Active Antenna Systems

In the future mobile communication, with continuously growing data traffic of mobile terminals and the increasing number of UEs, it is significant to bring in a new technology to the existing LTE network to meet the UE’s experience. In the follow-up evolution of LTE-A technology, active antenna system(AAS) as a technology can improve system capacity and effectively reuse frequency resource. A beam of vertical plane is introduced in AAS. With reasonable adjustment of antenna electrical down-tilt and azimuth angle, AAS can increase area coverage and improve the system capacity.Based on the LTE vertical sectorization model, this paper applies the active antenna element radiation model to LTE heterogeneous network scenarios. A cell interference coordination scheme is proposed in the LTE heterogeneous network with 3D MIMO model. The cell area is divided into 3 parts: the inside area and outside area is covered by the inside antenna beam and outside antenna beam, respectively; UEs in the middle annular region are served by both 2 beams of joint transmission to avoid interference. Femtocell clustering algorithm is proposed to effectively reuse frequency resources among femtocells and improve the total throughput of femtocell UEs. After femtocell clustering, the 3D beamforming algorithm is presented to solve the optimization problem including resources allocation and downtilt adjustment to improve the total throughput of Macro UEs and system performance.This paper designs an object tracking mechanism of user-specific elevation beamforming. An extended Kalman filter algorithm is used to track and predict UEs’ location. The BS obtains the prediction information of UEs’ location and calculates each UE’s downtilt and azimuth to realize effective beamforming tracking. When realizing the main beam to point to the direction of user signals based on prediction information, a cell throughput optimization model is established. A power allocation algorithm is proposed to solve the problem and improve the cell throughput.