Power Profile-Based Antenna Selection for Millimeter Wave MIMO with an All-Planar Lens Antenna Array

Abstract

Lens antenna arrays can significantly reduce the number of radio frequency (RF) chains and provide a cost-effective beamforming approach to millimeter-wave massive multiple-input multiple-output (MIMO) systems. However, the presence of curved fronts has imposed practical challenges in fabrication and system integration as the antennas have to be deployed on the lens focal curve or face. To this end, we analyze the massive MIMO system with an all-planar RF lens antenna array whose lens is made of metamaterials and the antennas are distributed on a two-dimensional (2D) plane. In terms of this structure, we then propose a power-profile based antenna selection method. Specifically, by considering the coupling among antenna elements and that between the RF-lens and the antenna array, the analyses regard the lens and antennas as an entity using a full-wave model. Antennas are selected according to the angle of arrivals (AoAs) of signals transmitted by users and the lens response to the incident wave from an arbitrary direction on antennas. Simulations are provided for verifying the system performance and to show: i) Specific gain responses on each element of the base station antenna array for user terminals distributed at different locations; and ii) The all-planar lens antenna array supports a spectrum efficiency upto 170.7 bps/Hz for a 25 GHz MIMO system with 50 user terminals and a signal-to-noise ratio (SNR) of 10 dB.