Comparison of Fractional Frequency Reuse Approaches in the OFDMA Cellular Downlink

Fractional frequency reuse (FFR) is an interference coordination technique well-suited to OFDMA based wireless networks wherein cells are partitioned into spatial regions with different frequency reuse factors. This work focuses on evaluating the two main types of FFR deployments: Strict FFR and Soft Frequency Reuse (SFR). Relevant metrics are discussed, including outage probability, network throughput, spectral efficiency, and average cell-edge user SINR. In addition to analytical expressions for outage probability, system simulations are used to compare Strict FFR and SFR with universal frequency reuse based on a typical OFDMA deployment and uniformly distributed users. Based on the analysis and numerical results, system design guidelines and a detailed picture of the tradeoffs associated with the FFR systems are presented, showing that Strict FFR provides the greatest overall network throughput and highest cell-edge user SINR, while SFR balances the requirements of interference reduction and resource efficiency.