Improving Energy Efficiency of Two-tier OFDMA Femtocell Networks with Distributed Power Control

This paper addresses how to improve the energy efficiency of two-tier OFDMA femtocell networks using power control. Firstly, the energy efficiencies of two typical power control methods are analyzed, including fixed power setting (FPS) and minimum power consumption (MPC) methods. Then a distributed maximum energy efficiency (MEE) method is proposed. Each macrocell and femtocell dynamically adjusts the transmission power of its available subchannels to individually maximize its energy efficiency. Furthermore, the optimal power control solution is obtained with the augmented Lagrange multiplier method. Simulation results show that the energy efficiency of MPC method is extremely low and increases very slowly even more femtocells installed. And because of severe cross-tier interference, the energy efficiency of FPS method will become worse with dense deployment of femtocells. The proposed distributed MEE power control method can preferably improve the energy efficiency of two-tier OFDMA femtocell networks, and obtain a good tradeoff between energy efficiency and spectrum efficiency.