Hybrid TDOA/AOA Indoor Positioning and Tracking Using Extended Kalman Filters

A hybrid time-difference-of-arrival / angle-of-arrival (TDOA/AOA) positioning technique for indoor ultra wideband (UWB) systems is presented in this paper. The non line-of-sight (NLOS) propagation error is considered one of the major error sources in location systems; therefore, NLOS identification and mitigation technique with Kalman filters are utilized to reduce the NLOS time-of-arrival (TOA) errors in indoor UWB environments. To deal with the effects of inaccurate NLOS AOA data, an AOA selection process is included. An adjustable extended Kalman filter (EKF) structure is used to process the formulated TDOA and selected AOA measurements for mobile positioning and tracking. The simulation results show that the proposed hybrid scheme can effectively respond to the NLOS/LOS changes in the UWB environment, and improve the position accuracy.