Fractional Frequency Reuse Scheme With Two and Three Regions For Multi-cell OFDMA Systems

The co-channel cell interference (CCI) becomes the major performance degradation factor for multi-cell OFDMA systems. In this paper, we propose two fractional frequency reuse (FFR) schemes that can efficiently avoid the CCI in the cell edge: scheme I where each cell is divided into two regions: the central region and the edge region. In the central region, the frequency reuse is set to 1. In the edge region, according to a difference-set and using the sectorization technique, the FFR of 3/7 and 4/7 have been applied. In the scheme II, each cell is partitioned into three regions: the central region, the middle region and the edge region. The FFR of 1, 2/3 and 3/7 are used correspondingly to the three regions. In two proposed schemes, an optimal dimension of the central region has been achieved by maximizing the average to variance ratio. In the cell edge of two proposed schemes, by using the difference-set notion and adding more antenna, the FFR of 3/7 and 4/7 can provide more diversity gain in selecting the serving sector than the classical schemes with reuse 1 and 3. Simulation results show that the proposed scheme is a powerful solution for CCI avoidance in the edge of the cell. keywordsFractional Frequency Reuse, OFDMA, Co-channel Cell Interference.