Near-Field Beamfocusing, Localization, and Channel Estimation with Modular Linear Arrays

TL;DR

This paper explores how modular linear arrays can achieve near-field beamfocusing and localization, enabling multiplexing and efficient channel estimation without increasing antenna count or processing complexity.

Contribution

It introduces a novel MLA architecture for near-field beamfocusing, providing mathematical analysis and a new localization method for improved wireless communication.

Findings

MLAs enable near-field beamfocusing with fewer antennas.

The proposed localization method efficiently estimates channel parameters.

Simulations validate analytical models and demonstrate practical benefits.

Abstract

This paper investigates how near-field beamfocusing can be achieved using a modular linear array (MLA), composed of multiple widely spaced uniform linear arrays (ULAs). The MLA architecture extends the aperture length of a standard ULA without adding additional antennas, thereby enabling near-field beamfocusing without increasing processing complexity. Unlike conventional far-field beamforming, near-field beamfocusing enables simultaneous data transmission to multiple users at different distances in the same angular interval, offering significant multiplexing gains. We present a detailed mathematical analysis of the beamwidth and beamdepth achievable with the MLA and show that by appropriately selecting the number of antennas in each constituent ULA, ideal near-field beamfocusing can be realized. In addition, we propose a computationally efficient localization method that fuses estimates from each ULA, enabling efficient parametric channel estimation. Simulation results confirm the accuracy of the analytical expressions and that MLAs achieve near-field beamfocusing with a limited number of antennas, making them a promising solution for next-generation wireless systems.