Optimal Fractional Frequency Reuse in OFDMA Based Wireless Networks

Fractional frequency reuse (FFR) is often used in interference-limited systems to improve coverage in cellular networks. Its cost is reducing the amount of available resources. In this paper, we intend to propose the FFR scheme by introducing the concept of normalized spectral efficiency (nSE). With the optimal frequency reuse factor (FRF), the FFR scheme can maximize the system SE with throughput improvement of cell-edge users. To solve the optimal problem, we divide it into two sub-problems. However, this scheme is asymptotically optimal with the assumption of the uniform distributions of signal and interference in sectors. The simulation results demonstrate the gain of the system SE is about 3% by our FFR scheme.