Antenna selection and transmission power for energy efficiency in downlink massive MIMO systems

Abstract

Massive multiinput-multioutput (M-MIMO) systems are crucial for maximizing energy efficiency (EE) infifth-generation (5G) wireless networks. A M-MIMO system’s achievable high data rate is highly related to the numberof antennas, but increasing the number of antennas the system raises energy consumption. In this paper, we deriveergodic EE based on the optimal transmit power and joint optimization antenna selection (AS) with impact pilot reusesequences (PRSs). We apply Newton’s method and the Lagrange multiplier to derive jointly optimized AS and optimaltransmission power under the effect of PRSs. The proposed algorithm prevents repeated searching for joint optimalAS and optimal transmission power to reduce the complexity caused by an increasing number of antennas. From thesimulation results, we conclude that EE could be maximized by employing the minimal PRSs and transmission powerthat are greater than the circuit’s power consumption. The proposed algorithm offers maximum EE by repeating aminimizing pilot signal until the optimal AS and transmission power are achieved.