Energy-Efficient Beamforming for 3.5Â GHz 5G Cellular Networks based on 3D Spatial Channel Characteristics

The base station (BS) equipments and downlink transmission consume the major energy of cellular networks. For the 5G network, the large amount of antenna elements of massive MIMO require energy-efficient solutions. In this work, we propose a new antenna muting scheme for beamforming taking into account the spatial multipath propagation characteristics of the cellular channels. First we combine the antenna array radiation pattern and the channel angular power spectra at the BS and define the spatial reception gain (SRG). Then the minimum number of antennas to be activated is determined according to the multipath spatial profile and the SRG requirement to reduce energy consumption and guarantee user service provision. Furthermore, we performed a field measurement campaign on the 3.5 GHz rural macrocell (RMa) channels by using a 3D MIMO sounder. The transmitter was installed on the top of a 5-story building and the receiver was moved to 152 positions along four routes. We measured the azimuth and elevation power spectra (APS and EPS) and built Laplace distribution model for the spectra. Finally, we analyze the impact of the channel parameter statistics and SRG threshold on the energy efficiency of the proposed scheme and evaluate the performance in the RMa scenario based on the spatial channel models.