Use of DVB-T signals for positioning in dynamic scenarios

Recently, the research related to positioning has been motivated by the significant growth of location-based services, such as car navigation and mobile-positioning. But once the users enter into a difficult environment (e.g. dense urban or indoor areas), the Global Navigation Satellite Systems (GNSS), which is the main system to rely on to locate a user in an open area, exhibits degraded performance in terms of precision and availability. The use of signals-of-opportunity is one of the solutions to replace or assist GNSS in these environments. These signals are designed to provide a service in dense urban area. Therefore they can be found in location where GNSS shows poor performance or it is totally unavailable. Normally these signals have a quite good SNR due to the error probability requirement, and thus they have the potential of better positioning performance. This paper investigates the potential of the digital TV European standard DVB-T to supply a navigation service as a supplement to GNSS in dynamic scenarios. The method analyzed in the paper exploits the scattered pilot subcarriers contained in the OFDM symbols to calculate the propagation time of different signals. The accurate synchronization is given by a Delay-Lock Loop (DLL) and a re-acquisition block is implemented in order to reform the tracking process when the correlation peak jumps from one sample to the adjacent samples. The Extended Kalman Filter (EKF) is used to compute the position and simulation results are present to validate the method