Exploiting Moving Arrays for Near-Field Sensing

TL;DR

This paper demonstrates that moving antenna arrays significantly improve near-field sensing capabilities by enlarging the effective aperture, enabling more accurate 2D target localization with limited antenna elements.

Contribution

It introduces a novel moving array design for near-field MIMO sensing and analyzes its fundamental performance limits via the CRB, showing substantial improvements over fixed arrays.

Findings

Moving arrays enlarge the effective aperture for sensing.

The CRB with moving arrays approaches that of a large fixed array.

Numerical results confirm enhanced localization accuracy.

Abstract

This letter exploits moving arrays to enable nearfield multiple-input multiple-output (MIMO) sensing via a limited number of antenna elements. We consider a scenario where a base station (BS) is equipped with a uniform linear array (ULA) on a moving platform. The objective is to locate a point target in the two-dimensional (2D) space by leveraging the near-field channel characteristics created by the movement of antenna arrays. Under this setup, we analyze the Cramer-Rao bound (CRB) for estimating the target's 2D coordinate, which provides the fundamental sensing performance limits for localization. It is revealed that our proposed design with a moving array achieves a CRB that is proportional to the CRB obtained by an equivalent extremely large ULA matching the platform's size. This shows that the movement of antenna array significantly enlarges its effective aperture to enable near-field sensing. Numerical results show that the proposed moving array design substantially enhances the target estimation performance compared to the conventional fixed array benchmark.