Energy-efficient power allocation algorithm for heterogeneous OFDM downlink systems

The energy-efficient design for heterogeneous OFDM downlink systems has attracted much attention since the problem of environmental pollution becomes dramatically serious. The core issue of the problem is power optimization. In this paper, the optimization problem is modeled as a multi-cell OFDM downlink heterogeneous system and the energy efficiency is calculated as the total throughput divided by the total power consumption. To solve the problem we first derive the relationship between the total power consumption and the system energy efficiency. Then the existence of the unique optimal value of the energy efficiency, which can be get by adjusting the transmit power, is proved. Thus, an improved water-filling algorithm is proposed to achieve the maximum energy efficiency of the system but the complexity is too high for the current system. Then we propose a distributed suboptimal algorithm to approach the optimal value. It adjusts the transmit power of each cell independently and finally converges by a certain number of iterations. Simulation results illustrate the features of the energy efficiency and show the proposed algorithm is feasible and effective.