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Accuracy Characterization for Metropolitan-scale Wi-Fi Localization. March 3, 2010 Hon Lung Chu. Place Lab. Protocol which: Gives ubiquitous Wi-Fi based localization Trades accuracy for availability Accuracy: 13-40 meters Require mapping and “training”
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Accuracy Characterization for Metropolitan-scale Wi-Fi Localization March 3, 2010 Hon Lung Chu
Place Lab • Protocol which: • Gives ubiquitous Wi-Fi based localization • Trades accuracy for availability • Accuracy: 13-40 meters • Require mapping and “training” • Authors claim half an hour to map an entire city neighborhood • This is still less than some indoors calibrated system
Key Idea How do we get this?
Localization: Response Rate This is much better!
Algorithm #2: Fingerprinting • Match up the list of APs
Algorithm #3: Particle Filters • Probability-based • Using signal strength and response rate
Result • “Best algorithm varies based on location • Fingerprinting works best overall • Protocol worked best in suburban with a high-density of APs • Can tolerate 50% AP lost • Requires max mean distance of 10 meters to nearest AP
What’s next? • Dynamically switch algorithm based on location and density • Build the Wifi database