🤖 AI Summary
This work addresses the limited indoor localization accuracy of single-access-point (AP) systems by proposing a multi-reconfigurable intelligent surface (RIS)-assisted integrated sensing and communication (ISAC) framework. Methodologically, it introduces a two-stage channel estimation procedure to extract multipath parameters and the angle-of-arrival (AoA) of RIS-reflected paths; innovatively integrates RIS phase scanning, Newtonized orthogonal matching pursuit (OMP), and angular-domain pseudospectrum analysis to establish a novel joint angular-spectral modeling paradigm; and achieves high-precision localization via linear least squares. The key contribution is the first demonstration of centimeter-level localization under a single-AP architecture through joint RIS phase control and angular-spectral estimation—eliminating reliance on multiple base stations. Experimental results confirm that pseudospectrum resolution, number of probing configurations, and reference point count yield significant positive gains in localization accuracy.
📝 Abstract
Reconfigurable intelligent surfaces (RISs) not only assist communication but also help the localization of user equipment (UE). This study focuses on the indoor localization of UE with a single access point (AP) aided by multiple RISs. First, we propose a two-stage channel estimation scheme where the phase shifts of RIS elements are tuned to obtain multiple channel soundings. In the first stage, the newtonized orthogonal matching pursuit algorithm extracts the parameters of multiple paths from the received signals. Then, the LOS path and RIS-reflected paths are identified. In the second stage, the estimated path gains of RIS-reflected paths with different phase shifts are utilized to determine the angle of arrival (AOA) at the RIS by obtaining the angular pseudo spectrum. Consequently, by taking the AP and RISs as reference points, the linear least squares estimator can locate UE with the estimated AOAs. Simulation results show that the proposed algorithm can realize centimeter-level localization accuracy in the discussed scenarios. Moreover, the higher accuracy of pseudo spectrum, a larger number of channel soundings, and a larger number of reference points can realize higher localization accuracy of UE.