A Hybrid TDOA/AOA Positioning Technique for Indoor UWB Systems

A hybrid TDOA/AOA positioning technique for indoor ultra wideband (UWB) systems is presented in this paper. The UWB system is a potential candidate for improving the location accuracy of indoor positioning due to the fine-resolution characteristic of the UWB signals. The hybrid technique consists of extended Kalman filters (EKF’s), which process time difference of arrival (TDOA) and angle of arrival (AOA) for location estimation. The non line-of-sight (NLOS) propagation error is considered one of the major error sources in location systems. Mitigation techniques are generally utilized to reduce the time-based NLOS errors. Inaccurate AOA information in the NLOS environment therefore becomes the major error source in positioning and tracking. An AOA selection process is presented for suppressing the impact. An adjustable EKF structure for the selected TDOA/AOA information is used in the indoor geolocation architecture. The simulation results show that the proposed hybrid technique can effectively respond to the NLOS/LOS changes in the UWB environment, and can efficiently improve the position accuracy.