Energy-efficient power control for Fractional Frequency Reuse

With the growing concern over energy consumption, green communication is becoming more and more important. Lots of efforts have been put into investigating in energy-efficient wireless systems. Since Fractional Frequency Reuse (FFR) is a widely-used Inter-cell-interference coordination scheme in the OFDMA wireless network, we consider the energy-efficient power control in the FFR system. With demanded user rate constraints, we aim at minimizing the Joule consumed per transmission bit per-cell in the downlink. Based on Dinkelbach´s theory, we transform the objective function into a parametric programming problem. By proving the problem is convex, we derive the optimal analytical solution by Karush-Kuhn-Tucker (KKT) conditions, along with an energy-efficient power control algorithm. Numerical results are given to verify our analysis, and demonstrate that the power control algorithm significantly improves the energy efficiency in FFR. The optimal frequency reuse factor is also given when considering the fairness of energy efficiency and power consumption.