Fractional frequency reuse for irregular geometry based heterogeneous cellular networks

Indoor coverage and capacity are the major limitations of the current cellular systems. In such perspective, femtocells deployment has attracted considerable interest. However, the random and co-channel deployment of femtocells poses severe interference management challenges, especially at the cell edges. Recently, Fractional Frequency Reuse (FFR) has emerged an attractive technique for co-tier and cross-tier interference in multi-tier cellular deployment. However, most of the previous work analyzes the performance of FFR for perfect cell geometry models. Applying regular resource of the standard FFR scheme to the realistic cellular networks with high irregularity in the cell geometry and channel conditions leads to sub-optimal performance. In this paper we investigate the performance of FFR for two-tier cellular network based on irregular cell geometry. To capture the realistic network scenario the position of Macro Base Stations (MBSs) and Femto Base Station (FBSs) are modeled with Hard Core Point Process (HCPP) and Poisson Point Process (PPP) respectively. Furthermore, Sectored-FFR scheme with optimal sub-band allocation is proposed in this paper and the capacity of the system is evaluated. Simulation results show that the proposed Sectored-FFR scheme outperforms the conventional FFR schemes in terms of throughput and capacity.