On Energy Efficiency Maximization in Downlink MIMO Systems Exploiting Multiuser Diversity

Energy efficiency (EE) maximization in MIMO systems has received much attention in next generation wireless communications. Within recent years, a lot of great works have been proposed to improve EE dramatically by power allocation and/or antenna selection. However, the systems significantly exploiting multiuser diversity were not considered in these works. With rapid popularization of wireless communication devices, the increasing density of user equipments (UEs) brings more multiuser diversity gain to be exploited. In this letter, we study the joint EE maximization over power allocation, UE and antenna selection. It will be shown that the maximum EE can be achieved by switching on all the antennas and selecting as many UEs as possible in a time slot with significant multiuser diversity. Simulation results demonstrate that with over tens of UEs, the proposed strategy can achieve less than 2% loss of EE compared to exhaustive antenna set selection.