Study on Indoor Positioning of Eliminating NLOS Signals Through Dynamically Adjusting Reflected Signals by RIS

Indoor positioning system faces challenges in accuracy due to non line of sight (NLOS) paths. Effectively addressing NLOS paths are paramount for improving the precision of such systems. Upon integration into the local wireless communication network, Reconfigurable Intelligent Surfaces (RIS) offer a groundbreaking solution for NLOS paths processing. This paper introduces a novel method known as Dynamically regulating reflected signals through RIS for Positioning (DRP). The proposed DRP method involves the dynamic adjustment of the RIS reflecting matrix by the receiver (Rx). This adjustment is aimed at capturing the NLOS signals reflected by RIS, enabling their cancellation with the random NLOS signals at the Rx. Subsequently, the signals arriving at the Rx are processed, leaving only line of sight (LOS) signals for precise positioning. The method leverages dynamic regulation of RIS's reflecting coefficient, considering both angle of arrival (AOA) and time of flight (TOF). This ensures that the regulated reflected signals by RIS effectively nullify other NLOS signals at the Rx. Simulation results demonstrate the efficacy of the DRP method, confirming the elimination of NLOS signals through verification using the MUSIC algorithm. Comparative analysis with positioning methods influenced by NLOS signals reveal a reduced positioning error with the DRP method. This approach presents a promising avenue for enhancing indoor positioning accuracy by mitigating the impact of NLOS paths through dynamic adjustment of RIS signals.