Toward an Accurate Acoustic Localization System
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In this dissertation, we propose an accurate and fast multi-pair simultaneous localization systems for smartphones without the need of infrastructure support. The system is a purely software-based solution (an App), which uses only the basic set of commodity smartphone capabilities including speakers, microphones, and Wi-Fi/Bluetooth. Audible-band acoustic signals and Wi-Fi/Bluetooth are jointly utilized for time of arrival (TOA)-based ranging. To simultaneously offer multi-smartphone-pair ranging, the acoustic chirps are encoded by Gold sequences, which has been extensively used in Code Division Multiple Access (CDMA) systems. We designed and implemented a fast One-way acoustic communication multi-pair ranging system as well as more accurate two-way acoustic communication multi-pair ranging system for comparison. Obtained ranges then will be used as input to a range-based localization approach in which the mobile devices can localize themselves related to each other. Our design is scalable with respect to the number of devices. The system is server-less and mobile devices compute their position locally so our system improves user privacy. Through extensive experimental evaluations over 8 different smartphones, the proposed system's positioning errors are around one meter and ranging errors are only a few centimeters for the actual phone-to-phone distances up to 60 meters in both indoor and outdoor environments.