Analysis on the TOA Tracking With DVB-T Signals for Positioning

The digital television signal is a promising signal of opportunity for ubiquitous wireless positioning. This letter analyzes the time of arrival (TOA) tracking errors of the European standard digital video broadcasting-terrestrial (DVB-T) signals in the context of positioning. The Cramér-Rao lower bound on the unsmoothed TOA estimation is derived and an information-theoretic lower bound (ITLB) is further computed on the smoothed TOA tracking errors in delay locked loop (DLL). Theoretical analysis shows that, the increase of the bandwidth of the equivalent loop filter will lead to larger DLL tracking errors. Despite different bandwidth of the loop filters, the tracking errors derived in theory are asymptotic to ITLB with the increase of signal-noise ratio. Comparatively, the theoretical results of the DLL tracking errors are slightly larger than the ITLB, which is due to the inequality and nonlinear approximation used in the analysis. Theoretical analysis has also verified the effectiveness of the DVB-T signals to be able to achieve high accuracy in positioning.