Multi-RIS-assisted Millimeter Wave Single Base Station Localization

Reconfigurable Intelligent Surface (RIS) technology provides solutions for high accuracy localization in non-line-of-sight (NLOS) environments. In the NLOS environment, this paper proposes a single-base-station localization method based on multiple RISs. The proposed localization method first jointly estimates the time of arrival (TOA) and angle of arrival (AOA) of different signals through different RISs, and then employs the time difference of arrival (TDOA) to estimate the location of the user equipment (UE). The proposed localization method can improve the localization accuracy by increasing the number of orthogonal frequency division multiplexing (OFDM) pilot symbols and optimizing the coefficients of RIS elements. The simulation results show that the localization accuracy of the proposed scheme can be improved to be 1 cm when the coefficients of RIS elements are optimized.