Throughput Optimization in MU-MIMO Systems via Coordinated Vertical Double-Beam Tilting

In this paper, we propose a novel framework called coordinated double-beam tilting to improve the throughput of multiple-input multiple-output (MIMO) system in a single cell via determining the tilting angles of two beams adaptively in a coordinated fashion. In this framework, two antenna beams adjust their tilting angles jointly based on the location of users to maximize the sum throughput of the scheduled users, denoted as coordinated user-specific double-beam tilting (CUSDBT) and coordinated vertical region-specific double-beam tilting (CVRSDBT). Assuming the availability of location information of scheduled users, accurate analytical expression for cell average achievable rate is provided. To determine the optimal tilting angles for BS beams to maximize sum throughput, Dividing Rectangle (DIRECT) method, an effective approach for optimization problems, is applied. Simulation results show that the proposed coordinated double-beam tilting scheme outperforms the conventional antenna tilting schemes.