Fundamental Analysis of 3D 6G-Localization Using Reconfigurable Intelligent Surface.

Reconfigurable intelligent surface (RIS) is a promising technique in the 6G communication system, which effectively improves the wireless propagation channel. Moreover, the RIS also benefits localization performance since it helps avoid the non-line-of-sight channel when there are obstacles. In this paper, we mainly analyze the 3D localization performance of the millimeter-wave (mmWave) system with a given fixed RIS. The Cramer lower bound (CRLB) is derived for our proposed 3D RIS-based wireless propagation channel. We analyze the localization accuracy of time-of-arrival (TOA) and angle-of-arrival (AOA). The results indicate that the RIS-based localization method can significantly improve localization accuracy, and centimeter-level localization can be attained. In addition, the localization based on TOA outperforms that based on the AOA when the number of the Rx and RIS units is fixed.