ASTARS empowered Satellite Positioning Approach for Urban Canyons and Indoor Environments

TL;DR

This paper introduces ASTARS, a novel satellite positioning method using reconfigurable surfaces to improve accuracy in urban canyons and indoors, outperforming traditional NLoS techniques.

Contribution

The paper presents a new ASTARS approach that actively reflects and transmits signals to enhance satellite positioning in challenging environments, with a detailed error analysis and simulation validation.

Findings

Achieves positioning errors under 4 meters in NLoS conditions with 10 ns synchronization accuracy.

Outperforms conventional NLoS methods with errors exceeding 7 meters.

Additional errors from the method do not surpass 3 meters within specified synchronization errors.

Abstract

To mitigate the loss of satellite navigation signals in urban canyons and indoor environments, we propose an active simultaneous transmitting and reflecting reconfigurable intelligent surface (ASTARS) empowered satellite positioning approach. Deployed on building structures, ASTARS reflects navigation signals to outdoor receivers in urban canyons and transmits signals indoors to bypass obstructions, providing high-precision positioning services to receivers in non-line-of-sight (NLoS) areas. The path between ASTARS and the receiver is defined as the extended line-of-sight (ELoS) path and an improved carrier phase observation equation is derived to accommodate that. The receiver compensates for its clock bias through network time synchronization, corrects the actual signal path distance to the satellite-to-receiver distance through a distance correction algorithm, and determines its position by using the least squares (LS) method. Mathematical modeling of the errors introduced by the proposed method is conducted, followed by simulation analysis to assess their impact. Simulation results show that: 1) in areas where GNSS signals are blocked, with time synchronization accuracy within a 10 ns error range, the proposed method provides positioning services with errors not exceeding 4 m for both indoor and outdoor receivers, outperforming conventional NLoS methods with positioning errors of more than 7 m; 2) the additional errors introduced by the proposed method do not exceed 3 m for time synchronization errors within 10 ns, which includes the phase shift, beamwidth error, time synchronization errors, and satellite distribution errors, outperforming traditional NLoS methods, which typically produce positioning errors greater than 5 m.