On-Demand Fingerprint Selection for 802.11-based Positioning Systems
TR-2007-008. (2007)Abstract
Abstract
Fingerprinting is a popular technology for 802.11-
based positioning systems: Radio characteristics from
different access points are measured at various positions
and stored in a database. The database is copied to all
mobile devices, and when a position is needed, the devices
compares its currently measured radio characteristics
with the database entries. In this paper, we present
two on-demand fingerprint selection algorithms to avoid
the cumbersome and time-consuming approach of manually
copying all fingerprints. Our algorithms only request
those fingerprints from the database that are currently required
to compute a position. The two algorithms differ
in the way they shape the region for which fingerprints
are requested. On-demand selection also allows storagerestricted
mobile devices to utilize the positioning system.
We carefully evaluate our algorithms in a real-world experiment.
The results show that our algorithms do not
harm the position accuracy of the positioning system. In
addition, we analyze the space requirements of our algorithms
and show that the typical constraints of mobile
devices are met.