Evaluation of Relative Clock Stability in Cellular Networks

The relative stability of base transceiver station (BTS) clocks in cellular networks is studied. It is demonstrated that although BTS clocks are not perfectly synchronized to GPS, they are relatively stable with respect to each other, permitting exclusive navigation with cellular signals in the absence of global navigation satellite system (GNSS) signals. A navigation observable is developed leveraging the relative stability of BTS clocks and a stochastic dynamical model for the clock deviations is proposed. Experimental data to multiple BTSs over twenty-four hours are presented.