Abstract
With the growing demand on wireless multimedia services and omnipresent access, the energy consumption rises sharply. Consequently, energy efficiency (EE) has become an essential problem in the design of green radio. In order to reduce computational complexity, we separate the resource allocation into two steps: subcarrier allocation and power allocation. After subcarrier allocation, we adopt biogeography-based optimizing (BBO) algorithm to maximize energy efficiency in downlink orthogonal frequency division multiple access (OFDMA) system. Simulation results reveal that higher fairness demand causes lower EE. The proposed algorithm improves EE with meeting the requirement of fairness threshold. This algorithm also gives network operators insight into the tradeoff between EE and fairness. In practical cases, network operators can achieve the tradeoff between EE and fairness by adjusting fairness threshold.