Leveraging Large Reconfigurable Intelligent Surfaces as Anchors for Near-Field Positioning

In this work, we present a recent investigation on leveraging large reconfigurable intelligent surfaces (RISs) as anchors for positioning in wireless communication systems. Unlike existing approaches, we explicitly address the uncertainty arising from the substantial physical size of the RIS—particularly relevant when a user equipment (UE) resides in the near field—and propose a method that ensures accurate positioning under these conditions. We derive the corresponding Cramér-Rao bound (CRB) for our scheme and validate the effectiveness of our scheme through numerical experiments, highlighting both the feasibility and potential of our approach.