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