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Range-Free Localization in Wireless Sensor Networks Using Fuzzy Logic
Maja M. Velimirovic, Goran LJ. Djordjevic, Andrija S. Velimirovic and Dragan B. Denic

Sensor node localization with an acceptable accuracy is one of the most important challenges for location-aware applications of Wireless Sensor Networks (WSNs). The Received Signal Strength (RSS)-based localization techniques are very attractive because of their simplicity and low cost. However, those methods suffer from evident estimation errors. In our previous work, we developed fuzzy set-based localization method, called Fuzzy Ring Overlapping Range Free (FRORF) localization. In this paper we further extend the concept and propose an improved FRORF localization method, IFRORF for short, which uses two-layer fuzzy processing. IFRORF is an area-based localization approach that partitions the localization space into overlapping rings modeled as fuzzy sets with ambiguous boundaries, and then generates fuzzy set of regions by intersecting rings from different fuzzy ring sets. IFRORF estimates the location based on degrees of sensor node membership in regions in the fuzzy set of regions that are additionally tuned using the second layer of fuzzy processing. Simulations demonstrate that IFRORF method outperforms localization accuracy of FRORF.

Keywords: Wireless sensor networks, localization, received signal strength, ringoverlapping localization, fuzzy set theory.

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