Enhanced Fractional Frequency Reuse to Increase Capacity of OFDMA Systems

Abstract

Inter-cell interference (ICI) mitigation is always a big challenge issue in cellular systems. In this work we propose an Enhanced Fractional Frequency Reuse (EFFR) scheme combined with power allocation and an interference-aware reuse mechanism to achieve not only ICI limitation at cell edge but also enhancement of overall cell capacity in orthogonal frequency division multiple access (OFDMA) based communication networks. The EFFR scheme divides the whole available bandwidth into a Primary Segment and a Secondary Segment. The exclusive reuse-3 subchannels in the Primary Segment will be prior used by cell-edge users with higher transmission power, whereas the remaining subchannels are all reuse-1 subchannels allowing to be used with lower power. In addition, the resources in the Secondary Segment will be occupied by means of signal-to-interference-ratio (SINR) estimation. We implement the proposed EFFR scheme in a system-level simulator and compare its performance with the well-known Soft Frequency Reuse (SFR) scheme and the classical reuse-1 scheme. In order to investigate the impact on the performance by power allocation, schemes are simulated with various power masks, and using a scenario with surrounding cells up to 2nd-tier. Simulation results show that the EFFR scheme is more flexible and robust than the SFR scheme, and can gain substantial improvements in terms of both, the overall cell capacity as well as the cell-edge user performance.