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arXiv · 2407.20264

Beam Focusing for Near-Field Multi-User Localization

Qianyu Yang·Anna Guerra·Francesco Guidi·Nir Shlezinger·Haiyang Zhang·Davide Dardari·Baoyun Wang·Yonina C. Eldar
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Abstract

Extremely large-scale antenna arrays are poised to play a pivotal role in sixth-generation (6G) networks. Utilizing such arrays often results in a near-field spherical wave transmission environment, enabling the generation of focused beams, which introduces new degrees of freedom for wireless localization. In this paper, we consider a beam-focusing design for localizing multiple sources in the radiating near-field. Our formulation accommodates various expected types of implementations of large antenna arrays, including hybrid analog/digital architectures and dynamic metasurface antennas (DMAs). We consider a direct localization estimation method exploiting curvature-of-arrival of impinging spherical wavefront to obtain user positions. In this regard, we adopt a two-stage approach configuring the array to optimize near-field positioning. In the first step, we focus only on adjusting the array coefficients to minimize the estimation error. We obtain a closed-form approximate solution based on projection and the better one based on the Riemann gradient algorithm. We then extend this approach to simultaneously localize and focus the beams via a sub-optimal iterative approach that does not rely on such knowledge. The simulation results show that near-field localization accuracy based on a hybrid array or DMA can achieve performance close to that of fully digital arrays at a lower cost, and DMAs can attain better performance than hybrid solutions with the same aperture.

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Qianyu Yang, Anna Guerra, Francesco Guidi, Nir Shlezinger, Haiyang Zhang, Davide Dardari, Baoyun Wang, Yonina C. Eldar. 2024-07-24. Beam Focusing for Near-Field Multi-User Localization. https://arxiv.org/abs/2407.20264

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