Closed-Form Expressions for LoS User Localization at an Uniform Linear Array Applicable to Both Near-Field and Far-Field

We present a scheme for line-of-sight user localization at a uniform linear array (ULA) applicable to both near-field and far-field. The proposed scheme leads to closed-form expressions for the estimates of the user location, distance and angle. The proposed scheme is based only on the phase differences between pilot signals received on neighboring antennas at the ULA. As a result, the proposed scheme can be implemented by a ULA with analog hardware and a single-tone pilot. One such analog hardware ULA is proposed. We provide numerical results with which we confirm our theoretical results and compare the proposed scheme with an existing localization scheme in the literature and to the Cramer-Reo bound.