Interference Control with Beamforming Coordination for Two-Tier Femtocell Networks and its Performance Analysis

In this paper, we propose a reduced-complexity beamforming coordination method for the emerging two-tier MIMO-femtocell systems. With a small overhead signaling, the proposed scheme implements the cross-tier interference control between the macrocell and the femtocell. Furthermore, we develop the exact analytical expressions of the ergodic capacity of selected users in both tiers. We show through selected numerical examples that our proposed beamforming coordination achieves significant performance gain over conventional systems while only requiring beam index and an angle information sharing between the two heterogeneous cells.