Accuracy Estimation of Multi-RISs Assisted Positioning in Indoor UWB System

Reconfigurable intelligent surfaces (RISs) can create additional reflection paths between the transmitter and the receiver. It can be leveraged to enhance indoor positioning accuracy. This letter analyzes the Cramér-Rao lower bound (CRLB) for position estimation by utilizing RISs in the ultra-wideband (UWB) system. Then, an optimization scheme for RIS phase shifts is proposed to further improve positioning accuracy. Initially, the channel parameters at the receiver are estimated. And a weighted least squares (WLS) positioning method is proposed to fuse the estimates of the reflection paths from multiple RISs. Simulation results confirm that the proposed method enhances positioning accuracy to approximately the CRLB in indoor wireless environments.