Robust TOA-based Navigation under Measurement Model Mismatch in Harsh Propagation Environments

Global Navigation Satellite Systems (GNSS) is the positioning technology of choice outdoors but it has many limitations to be used in safety-critical applications such Intelligent Transportation Systems (ITS). Namely, its performance clearly degrades in harsh propagation conditions, these systems are not reliable due to possible attacks, may not be available in GNSS-denied environments, and using standard architectures do not provide the precision needed in ITS. Among the different alternatives, Ultra-WideBand (UWB) ranging is a promising solution to achieve high positioning accuracy. The key points impacting any time-of-arrival (TOA) based navigation system are i) transmitters' geometry, and ii) a perfectly known transmitters' position. In this contribution we further analyze the performance loss of TOA-based navigation systems in real-life applications where we may have both transmitters' position mismatch and harsh propagation conditions, i.e., measurements corrupted by outliers. In addition, we propose a new robust filtering method able to cope with both effects. Illustrative simulation results are provided to support the discussion and show the performance improvement brought by the new methodology with respect to the state-of-the-art.