| This thesis presents a new mechanism for secure indoor localization through a combination of infrared and ultrasound signals. While a number of existing systems use ultrasound and radio frequency (RF) based localization, the use of RF gives rise to a series of operational difficulties including lack of localization privacy and collisions among the localization beacons. In this thesis, infrared is used to mitigate these limitations of RF. Collisions among the localization beacons, placed in different rooms, are avoided by leveraging the attenuation of infrared signals through walls and other indoor partition materials. Privacy is ensured by the complete isolation of the infrared signal across different rooms and hallways. Also, the unlicensed usage of infrared can provide a significant operational advantage compared to the RF based solutions.;We implement a time difference of arrival (TDOA) mechanism in which the localization beacons send simultaneous infrared and ultrasound pulses which are received at localization modules, which compute the distance to a beacon by measuring the TDOA between the IR and the US signals. Applications of such indoor localization systems include robot navigation, location-aware sensor network protocols, equipment localization, and various location-based wireless services. |
