Recently, the sustainable development strategy based on green energy conservation technology has become a general consensus of national governments, business circles and academia. While the growing communication technology brings convenience for people's life, the proportion of carbon component to the global greenhouse gas emission is not small due to the power consumption of the core network apparatus, the access network apparatus and the terminal for supporting communication, where the power consumption of the base station takes 60% to 70% of that of the whole communication system. It is desirable to reduce the power consumption of the communication system from the view of energy saving. On the other hand, the power consumption should not be reduced at the expense of a significant reduction in the user communication quality. Therefore, it becomes a key problem how to improve the energy efficiency of the base station apparatus. The cell density, as a key indicator for the network planning, has a vital effect on the energy efficiency of the whole communication system.