Positioning with OFDM based communications systems and GNSS in critical scenarios

The objective of this paper is an improvement of positioning accuracy in critical scenarios where measurements from communications systems and global navigation satellite systems (GNSSs) were combined. For the communications system we use time difference of arrival (TDOA) information obtained from an orthogonal frequency division multiplexing (OFDM) based communications system where underlying synchronization algorithms have been exploited. All available information is combined in an extended Kalman filter approach which additionally allows to track a moving mobile station in the scenario. Simulation results show the ability of the TDOA measurements to compensate unavailable satellites that are blocked, e.g., by buildings in an urban canyon situation. High performance improvement can be achieved especially in critical scenarios where the number of visible satellites is below the required four.