Accurate Indoor Location Tracking Exploiting Ultrasonic Reflections

Time difference of arrivals) (TDoA)-based location tracking systems using RF and ultrasonic signals often give unacceptable errors due to the line-of-sight limitation of the ultrasonic signal. To overcome this limitation, many researchers have devoted their efforts using various methods. To further enhance accuracy and improve performance, this paper proposes a novel TDoA-based location tracking technique that explicitly exploits ultrasonic reflections in location estimation. We also propose a reflection plane detection method, which makes system configuration easy for the proposed reflection-aware location tracking algorithm. The proposed system can achieve a high location accuracy with errors smaller than 35 cm even when the lines of sight of ultrasonic signals are frequently blocked and hence they are received through reflections.