Accurate Indoor Localization Using Acoustic Direction Finding via Smart Phones

We propose and implement a novel indoor localization scheme, Swadloon, built upon an accurate acoustic direction find-ing. Swadloon leverages sensors of the smartphone with-out the requirement of any specialized devices. The scheme Swadloon does not rely on any fingerprints and is very easy to use: a user only needs to shake the phone for a short dura-tion before walking and localization. Our Swadloon design exploits a key observation: the relative displacement and ve-locity of the phone-shaking movement corresponds to the subtle phase and frequency shift of the Doppler effects ex-perienced in the received acoustic signal by the phone. A novel method is designed to derive the direction from the phone to the acoustic source by combining the velocity cal-culated from the subtle Doppler shift with the one from th