Localization-Based Beam Focusing in Near-Field Communications

Abstract

Shifting 6G-and-beyond wireless systems to higher frequency bands and the utilization of massive multiple-input multiple-output arrays will extend the near-field region, affecting beamforming and user localization schemes. In this paper, we propose a localization-based beam-focusing design, in which the receive combiners are directly constructed from the steering vectors corresponding to the estimated user locations. To support this approach, we analyze the 2D-MUSIC algorithm by examining its spectrum in simplified, tractable setups with minimal numbers of antennas and users. Lastly, we compare the proposed localization-based beam focusing, with locations estimated via 2D-MUSIC, with pilot-based zero forcing in terms of uplink sum spectral efficiency. Our results show significant gains under dominant line-of-sight propagation, short coherence blocks, and high noise power typical of high-frequency systems.