Joint power allocation and antenna selection for energy-efficient OFDM D-MIMO systems

In this paper, we propose a joint power allocation and antenna selection scheme for orthogonal-frequency-division-multiplexing (OFDM) distributed multiple-input multiple-output (D-MIMO) systems. Our aim is to increase energy efficiency (EE), under the constraint of transmission power of each remote access unit (RAU). Because of the multi-objective and non-convex nature of the problem, obtaining the optimal solution is computationally complex. Therefore, a low-complexity suboptimal scheme is proposed. We first convert the multi-objective problem to a simpler single objective optimization problem. Then, we develop a sub-gradient power allocation algorithm, which improves EE than equal power allocation. To further increase EE, we adopt an antenna selection method based on large scale fading. Simulation results demonstrate that, compared with the conventional approaches, joint power allocation and antenna selection scheme significantly improves the EE.