Energy-efficient resource allocation for downlink OFDMA systems

In this paper, a new energy efficient resource allocation is designed to maximize the system throughput per unit-energy over frequency selective channels in OFDMA downlink transmissions. Based on a fixed optimization model, the base station allocates transmit power to subcarriers using Water-Filling method and each user has its own water level. The optimal solution of power allocation with a given subcarrier assignment is derived according to the relationship between energy efficiency (EE) and water level. Furthermore, a suboptimal algorithm for subcarrier scheduling is presented which can achieve a better EE with desirable transmission rate. Simulation results show that the proposed scheme can get a better balance between spectral efficiency (SE) and EE compared to the existing schemes.