Practical Robust Localization over Large-Scale 802.11 Wireless Networks

Authors

Andreas Haeberlen
Eliot Flannery
Andrew M. Ladd
Algis Rudys
Dan S. Wallach
Lydia E. Kavraki

Abstract

We demonstrate a system built using probabilistic techniques that allows for remarkably accurate localization across our entire office building using nothing more than the built-in signal intensity meter supplied by standard 802.11 cards. While prior systems have required significant investments of human labor to build a detailed signal map, we can train our system by spending less than one minute per office or region, walking around with a laptop and recording the observed signal intensities of our building's unmodified base stations. We actually collected over two minutes of data per office or region, about 28 man-hours of effort. Using less than half of this data to train the localizer, we can localize a user to the precise, correct location in over 95% of our attempts, across the entire building. Even in the most pathological cases, we almost never localize a user any more distant than to the neighboring office. A user can obtain this level of accuracy with only two or three signal intensity measurements, allowing for a high frame rate of localization results. Furthermore, with a brief calibration period, our system can be adapted to work with previously unknown user hardware. We present results demonstrating the robustness of our system against a variety of untrained time-varying phenomena, including the presence or absence of people in the building across the day. Our system is sufficiently robust to enable a variety of location-aware applications without requiring special-purpose hardware or complicated training and calibration procedures.

Published

The Tenth ACM International Conference on Mobile Computing and Networking (MOBICOM) (Philadelphia, PA), September 2004.

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BibTEX Entry

@InProceedings{mobicom2004localization,
        author = {Andreas Haeberlen and Eliot Flannery and Andrew M. Ladd and Algis Rudys and Dan S. Wallach and Lydia E. Kavraki},
        title = {Practical Robust Localization over Large-Scale {802.11} Wireless Networks},
        booktitle = {Proceedings of the Tenth ACM International Conference on Mobile Computing and Networking (MOBICOM)},
        year = 2002,
        address = {Philadelphia, PA},
        month = sep,
        note = {to appear}
}