Resource allocation in OFDMA networks with femto and macro-cells coexistence using Fractional Frequency Reuse (FFR)

Femto-cell is a recent solution that offers improved indoor coverage and enhances the system capacity. However, deploying femto-cells with macro-cells coexistence may introduce a phenomenon of interference. To remedy this problem, we propose in this paper a frequency allocation scheme for the downlink based on the Fractional Frequency Reuse (FFR). Unlike previous works in which a macro-cell is divided into two regions ( the inner and the outer regions ), our solution consists of dividing a cell into three regions, i.e, adding an intermediate region to exploit users diversity in the cell. We evaluate then the total throughput in a two-tier LTE femto-cells OFDMA network when varying the femto-cells number. The aim is to reduce interferences between both macro and femto cells and to maximize the total throughput. Simulation results show that by introducing a third region, the total throughput is considerably enhanced since the reuse factor is increased and a higher spectrum efficiency is achieved.