Rotatable URAs for line-of-sight MIMO transmission

Abstract

This paper considers line-of-sight multiple-input multiple-output communication, of interest at millimeter-wave and sub-terahertz frequencies. Building on how, with an angular rotation dependent on the signal-to-noise ratio (SNR), uniform linear arrays (ULAs) can tightly approach the capacity of such channels, we assess the performance of rotatable uniform rectangular arrays (URAs). The changeover from ULAs to URAs is motivated by the interest in reducing the array footprints. For both isotropic and directive antennas, various types of rotatable URAs are devised that—except at very low SNRs—perform remarkably close to their ULA counterparts with considerably smaller footprints.