Low complexity energy-efficient design for OFDMA systems with an elaborate power model

In this paper, we investigate the resource allocation for joint transmitter and receiver energy efficiency maximization in orthogonal frequency division multiple access (OFDMA) systems. An elaborate power dissipation model is proposed for OFDMA systems considering the transmission power from the base station side, the signal processing power and radio frequency (RF) circuit power from both sides. Then we formulate the energy efficiency maximization problem and propose a two-step method based on the relationship analysis of the single subcarrier-user (SU) pair energy efficiency and system energy efficiency. Specifically, we first pair each subcarrier with the user resulting in highest SU pair energy efficiency, which is motivated by a special case study. Then, we propose a linear complexity scheme by exploring the inherent fractional structure of the system energy efficiency, which is proved to be optimal for the power allocation with given SU pairing in the first step. Finally, we provide a sufficient condition under which our proposed two-step method is globally optimal. Numerical results demonstrate the effectiveness of the proposed method and we also find that exploiting more user diversity is not always beneficial from the perspective of energy efficiency.