A two-stage fuzzy logic approach for wireless LAN indoor positioning

Alternatively to GNSS, in indoor environments WLAN according to the IEEE 802.11 standard can provide location information by using signal strength measurements to access points (AP) and hence offers a smart synthesis of communication and navigation functionality. Especially the approach of pattern recognition of signal strength fingerprints can obtain location accuracies of 1 to 5 m. The presented approach makes use of this approach but goes further and takes up the idea of fuzzy logic theory since various information of the signal strength measurements can be used to form linguistic variables according to an assessment made by humans. The accuracy of the location results of the fuzzy logic approach is compared to the results of commercial WLAN positioning software as well as to a simple approach of processing Euclidian distances. Although still without the necessary fine tuning of the algorithms, the preliminary results already show that the fuzzy logic approach is very suitable since it obtains significant accuracy improvements, especially in large rooms and on sites not being in the vicinity of a calibration site.