Robust Ultrasonic Spread Spectrum Positioning System Using a AoA/ToA Method

This paper proposes a novel hybrid Time of Arrival (ToA) and Angle of Arrival (AoA) based system for 3D indoor location using ultrasonic spread spectrum signals. The proposed system differs from previously proposed hybrid systems in several ways - the mobile devices determines its own position, the consequent orientation problem is solved and the system uses spread spectrum techniques to improve robustness to noise and multipath. The system uses an inclinometer to allow the mobile to determine its own position. This paper compares the performance of the proposed hybrid system with that of a conventional ToA- only system. The hybrid system is found to reduce the number of base stations needed for 3D location of the mobile device, from three to two, and to provide more accurate location estimates under conditions of typical noise and room reverberation.