Load-aware beamforming and association for system-wide utility maximization

In the cellular systems, the performance can be severely degraded if the loads are imbalanced among cells. We consider a joint optimization of association control and beamforming to maximize a system-wide utility function as a means to balance the load across multiple cells. The beamforming weight vector can be adapted as the channel status varies, but it is not practical to change the user association from a cell to another at the same frequency. Accordingly, we propose algorithms to adapt the beamforming weight vectors according to the channel status variation during the runtime while the association control and the beamforming policy, affecting the runtime beamforming weight vector determination, are selected in a longer time scale. Simulation results demonstrate that the proposed algorithms significantly improve the system-wide performance compared with legacy schemes by balancing the load.