Mitigation of inter-femtocell interference with adaptive fractional frequency reuse

In this paper, we consider the use of fractional frequency reuse (FFR) to mitigate inter-femtocell interference in multi-femtocell environments. The use of universal frequency reuse can be said optimum in terms of the ergodic system spectral efficiency. However, it may cause inter-femtocell interference near the cell edge, making it difficult to serve the whole cell coverage. To alleviate this problem, we adjust the frequency reuse factor with the aid of femtocell location information. The proposed scheme can provide reasonably high ergodic system spectral efficiency, while assuring a desired performance near the cell boundary. Simulation results show that the proposed scheme is quite effective in indoor environments such as residential or office buildings.