Energy-efficient transmission in massive MIMO environments

Abstract

Mobile data traffic exponentially grows according to the activation of wireless multimedia services associated with the prevalence of smart phone, social networking services and device-to-device communications. As a consequence, the wireless communication systems should be able to handle huge data traffic in an energy efficient manner. Massive multi-input multi-output (MIMO) systems have attracted much attention as a key technology for high data rate and energy efficient wireless transmission. It has theoretically been shown that massive MIMO systems can support energy efficient transmission with high array and multiplexing gain. However, massive MIMO systems may involve difficulty of implementation including high computational complexity and full-duplexing mode. Most of previous works on massive MIMO technology have been considered the improvement of energy efficiency by controlling the transmission power and resource allocation. However, we may have to consider power consumption in the antenna circuitry due to the use of a large number of antennas as well as in the signal transmission for energy efficient transmission. In this thesis, we consider energy-efficient signal transmission in cellular communication systems where base stations employ massive MIMO schemes. The use of massive MIMO schemes can provide transmission capacity larger than being desired. This aspect may suggest us to change the major operation concern of wireless communication systems from spectral efficiency to energy efficiency. It may be desirable to minimize power consumption to provide desired transmission performance. For energy-efficient transmission, most of conventional cellular systems only consider transmit power control with the aid of user and resource scheduling. In this thesis, in addition to the user and resource scheduling, we consider the scheduling of antenna resource associated with MIMO transmission mode to minimize the total power consumption. Taking into consideration of power consumption of antenna circuitry, we consider partial use of massive MIMO antennas to provide required transmission capacity while minimizing the total power consumption. Finally, the performance of the proposed transmission scheme is verified by computer simulation with the use of zero-forcing beamforming and maximum ratio transmission MIMO modes.