Exploiting wavefront curvature enables localization with limited infrastructure and hardware complexity. With the introduction of reconfigurable intelligent surfaces (RISs), new opportunities arise, in particular when the RIS is functioning as a lens receiver. We investigate the localization of a transmitter using a RIS-based lens in close proximity to a single receive antenna element attached to reception radio frequency chain. We perform a Fisher information analysis, evaluate the impact of different lens configurations, and propose a two-stage localization algorithm. Our results indicate that positional beamforming can lead to better performance when a priori location information is available, while random beamforming is preferred when a priori information is lacking. Our simulation results for a moderate size lens operating at 28 GHz showcased that decimeter-level accuracy can be attained within 3 meters to the lens.
@article{arxiv.2010.05617,
title = {Near-field Localization with a Reconfigurable Intelligent Surface Acting as Lens},
author = {Zohair Abu-Shaban and Kamran Keykhosravi and Musa Furkan Keskin and George C. Alexandropoulos and Gonzalo Seco-Granados and Henk Wymeersch},
journal= {arXiv preprint arXiv:2010.05617},
year = {2020}
}