Active RFID Fingerprinting for Indoor Positioning

Guenther Retscher, Qing Fu

Abstract:	In this paper the use of active RFID (Radio Frequency Identification) location fingerprinting is presented for indoor positioning of a pedestrian. The research is conducted in the ongoing research project UCPNAVI (Ubiquitous Carthograpy for Pedestrian Navigation) at the Vienna University of Technology. For location fingerprinting the signal strength values (received signal strength indication (RSSI) in RFID terms) to the surrounding RFID tags have to be determined at the user’s current location with a mobile RFID reader device. Two different phases are distinguished in location fingerprinting, i.e., an on-line or training phase where the RSSI to the RFID tags are measured at known locations and stored in a database and an off-line or positioning phase where the current RSSI measurements are used to obtain the user’s location. To estimate the current location of the user different approaches can be employed. The most common algorithm used is the ‘nearest neighbor’ (NN) algorithm. In this algorithm the Euclidean distance between the measurement of the RSSI and each fingerprint in the database is computed in signal strength space. The assignment of the measured RSSI to the location can be performed by different approaches, i.e., a direction-based approach (DBA), a tag-based approach (TBA), a direction-tag-based approach (DTBA) and a heading-based approach (HBA). These approaches have been developed and are tested in the experiments. Using location fingerprinting usually positioning accuracies on the few meter level can be achieved. This could be proven in the performed tests in an office building of the Vienna University of Technology. The main results of the conducted tests are presented and discussed in the paper.
Published in:	Proceedings of the 21st International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2008) September 16 - 19, 2008 Savannah International Convention Center Savannah, GA
Pages:	1812 - 1820
Cite this article:	Retscher, Guenther, Fu, Qing, "Active RFID Fingerprinting for Indoor Positioning," Proceedings of the 21st International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2008), Savannah, GA, September 2008, pp. 1812-1820.
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