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arXiv · 2505.07991

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

Alva Kosasih·Özlem Tuğfe Demir·Emil Björnson
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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.

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Alva Kosasih, Özlem Tuğfe Demir, Emil Björnson. 2025-05-12. Near-Field Beamfocusing, Localization, and Channel Estimation with Modular Linear Arrays. https://arxiv.org/abs/2505.07991

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