Energy efficiency analysis with circuit power consumption in massive MIMO systems

It was shown that the required transmit power to support a target achievable rate is inversely proportional to the number of antennas in massive multiple-input multiple-output (MIMO) systems [1]. However, the consumed power of the massive MIMO systems should include not only transmit power but also the fundamental power for operating the circuit at the transmitter, because the effect of circuit power consumption is more serious when the transmitter is equipped with massive number of antennas. Hence, to analyze the exact power consumption of massive MIMO systems, we investigate the energy efficiency for multiple cellular systems with large-scale antenna arrays under a consideration of circuit power consumption of each antenna. In particular, we propose a new power consumption model that considers not only transmit power on the power amplifier but also circuit power dissipated by analog devices and residually lossy factors in base stations (BSs). Through new energy efficiency formulation based on the proposed power consumption model, we analyze the tendency of the energy efficiency as the number of antennas increases and can see that the energy efficiency becomes a quasi-concave function with respect to the number of antennas. Finally, from the derived function of the energy efficiency, we determine the number of antennas to provide the maximum energy efficiency.