Uncaught signal imputation for accuracy enhancement of WLAN-based positioning systems

In this paper we propose a technique to enhance the accuracy of WiFi fingerprint-based localization by imputing uncaught access point (AP) signals of WiFi fingerprints. Two techniques were developed for this; one is to impute uncaught AP signals by referring to WiFi radio map (WRM) fingerprints at the very previous location, another is referring to WRM fingerprints obtained by predicting the next location. When we measured the accuracy of localization at an E-Mart, Seoul, Korea and a KAIST Library, Daejeon, Korea with and without uncaught signal imputation, the imputed signal resulted in around 30% better accuracy improvement than the signals without imputation. In addition, the imputation methods using WRM information showed significantly better accuracy than using a fixed value for uncaught AP signals. This indicates that the uncaught signal imputation, which was overlooked in the WLAN-based localization, should be incorporated with other filtering techniques for a more reliable and accurate localization.