Wi-Fi RTT/RSS fusion localization CRLB derivation and optimal access points layout design

The fine time measurement (FTM) protocol-based Wi-Fi RTT positioning is currently a research spotlight in the community. However, the performance evaluation methods of localization algorithms are relatively simplistic and lack theoretical basis. Furthermore, the impact of Wi-Fi access points (AP) layout on positioning accuracy has not been thoroughly studied. This paper focuses on smartphone-based Wi-Fi FTM as the research object. It derives the Cramer-Rao lower bound (CRLB) of the Wi-Fi RTT/RSS hybrid positioning method and clarifies the theoretical CRLB relationships of the single and hybrid positioning methods, which establishes a theoretical foundation for algorithm performance evaluation. The influence of Wi-Fi AP deployments on the localization accuracy of the RTT/RSS fusion positioning is studied, and an optimal access point layout approach for Wi-Fi RTT/RSS hybrid positioning is designed based on the enhanced genetic algorithm (EGA) and CRLB. Research shows that Wi-Fi RSS/RTT fusion localization is also an efficient FTM positioning method. The proposed EGA and CRLB-based optimal layout approach for Wi-Fi APs can quickly produce the optimal access point deployment strategy for the positioning area. The experimental results reveal that under the optimal layout of 7 Wi-Fi APs, the theoretical accuracy of Wi-Fi RSS, RTT, and RSS/RTT fusion positioning in the testing site of this manuscript is 0. 92, 1. 07 and 0. 61 m, respectively. The research work provides theoretical support for evaluating the performance of Wi-Fi FTM positioning and offers practical strategies for deploying Wi-Fi APs effectively, thereby reducing positioning investment. © 2024 SinoMaps Press. All rights reserved.