Performance Improvement of Fractional Frequency Reuse in WiMAX Network

The current WiMAX operators have to choose whether to utilize reuse-1 (R-1) or reuse-3 (R-3) frequency planning pattern. The R-1 pattern achieves high spectral efficiency but results in high inter-cell interference(ICI), especially at the cell-edge users. As for the R-3, it reduces the ICI and guarantees coverage to the cell-edge users. However, the R-3 pattern still achieves low cell-edge user throughput due to the reduction in the available bandwidth. In this paper, we aim to enhance the performance of the current WiMAX networks by considering multiple Fractional Frequency Reuse (FFR) schemes. We will show that the FFR can significantly improve the cell-edge users throughput with slight degradation in the spectral efficiency compared to the R-1 scenario. More specifically, we will characterize the performance of the FFR by considering multiple FFR algorithms including 2-threshold FFR and adaptive power FFR. Furthermore, we quantify the tradeoff between the the spectral efficiency and cell edge users throughput achieved by these FFR algorithms. The evaluation of these different FFR schemes is done via WiMAX (IEEE 802.16e) system level simulations (SLS).