Executive Summary : | Wireless networks are constantly evolving, but their performance is limited by the propagation environment. To overcome this limitation, reconfigurable intelligent surfaces (RIS) have been introduced as a two-dimensional surface with meta-material elements that can be reconfigured to partially control signal propagation, providing a smart radio environment for reliable wireless communication. This technology, combined with future 6G networks, has the potential to significantly improve network coverage and enhance localization services. Localization using wireless systems is important for various applications, including security, surveillance, augmented reality, and navigation. This proposal investigates the potential use of RIS for precise localization in diverse environments. Current technologies, such as synchronized pilot signal transmission in 4G and large antenna arrays in 5G, face limitations such as multipath fading, non-availability of LOS, and cooperation requirements between multiple base stations. By adding an RIS, these issues can be addressed, establishing an indirect link between user and base station, providing a synchronized reference point for accurate localization. The proposal proposes developing RIS-aided localization methods under both far-field and near-field scenarios. Accurate signal models will be developed in the presence of RIS under various propagation conditions, using band-specific models for accurate channel characterization. The approach for localization will involve estimating wireless channel parameters and using them to estimate user position. The Cramer Rao lower bounds will be derived to verify the accuracy of the proposed methods and characterize the asymptotic performance. |