Energy‐efficient Wireless OFDMA Networks

This chapter focuses on energy‐efficient (EE) transmission and resource‐allocation techniques for OFDMA networks. The origin of EE wireless networks is first reviewed, and some interesting open problems in the area are also discussed. Then, the fundamental principles of EE design for OFDMA networks are discussed. As the first step, the fundamental interrelationship between EE and spectral efficiency (SE) in downlink OFDMA networks is investigated and the impacts of channel gain and circuit power on the EE–SE relationship are analyzed. Next, a general EE–SE optimization framework is proposed, where the overall EE, SE and per‐user quality‐of‐service are all considered. Under this framework, EE proves to be quasiconcave in SE and decreases with SE when SE is large enough. Finally, the tradeoff between EE and delay for delay‐sensitive traffic in downlink OFDMA networks is analyzed by integrating information theory with the concept of effective capacity. The relationship between spectrum‐efficient and energy‐efficient designs, and the impact of system parameters, including circuit power and delay exponents, on the overall performance are also discussed.