Abstract

The accuracy of wireless localization systems depends on the precise acquisition of position-dependent signal parameters, which are often degraded by non-line-of-sight (NLOS) propagation. Urban environments with tall buildings frequently obstruct direct line-of-sight (LOS) paths, complicating localization. Conventional approaches typically require five or more receivers to ensure sufficient LOS paths for accurate positioning. However, in fully NLOS scenarios, these techniques are ineffective. This paper proposes a hybrid Time of Arrival/Received Signal Strength (TOA/RSS) localization system using three spatially deployed receivers and assumes no LOS paths are available. Reconfigurable intelligent surfaces (RISs) are introduced to mitigate NLOS effects, while weighted least squares (WLS) are applied and optimized through semi-definite programming (SDP) to address the non-convexity of the localization problem. Monte Carlo simulations demonstrate that the RIS-assisted system achieves a 50% improvement in localization accuracy and a 16% reduction in computational complexity compared to conventional NLOS mitigation approaches in hybrid TOA/RSS systems.

Key words: Wireless localization, Non-line-of-sight (NLOS) mitigation, Reconfigurable intelligent surfaces (RIS), Hybrid TOA/RSS, Semi-definite programming (SDP) optimization