Efficient coordinated beamforming and scheduling approaches for heterogeneous networks

Heterogeneous Networks deployment is considered one of the most promising enhancements to support future network capacity requests. However, access points densification means high frequency reuse and requires efficient interference management policies. This paper considers a coordinated scheduling/coordinated beamforming approach to deal with the intercell interference, and proposes optimal and heuristic solutions for selecting the beamforming weights and the sets of scheduled users, with the goal of maximizing the joint throughput and guaranteeing fairness among the cells. The selection of the sets of scheduled users is both optimally performed by resorting to the Hungarian method and to a low complexity iterative heuristic. Differently form previous approaches, scheduling is here performed on a physical resource block basis in order to take into account different data rate requests of the users, hence, the same macrocell user can be in pairs with different small cell users in different resource blocks and vice-versa. The effectiveness of the proposed schemes is validated by the achieved good throughput performance, and by the good agreement between optimal and sub-optimal solutions.