Robust Receiver Design for High Altitude Aircraft Navigation with Terrestrial Cellular Signals

A robust receiver design to exploit long-term evolution (LTE) terrestrial cellular signals of opportunity (SOPs) for high altitude aircraft navigation is presented. Conventional receivers employ phase-locked loops (PLLs) to track the carrier phase of received signals. In this paper, a Kalman filter (KF) is developed to replace the receiver's PLLs. To evaluate the performance of the proposed receiver, a flight campaign was conducted over two regions in California, USA: (i) Region A: Edwards Air Force Base (rural) and (ii) Region B: Palmdale (semi-urban). It is shown that the proposed receiver provides robust tracking of received LTE signals compared to a conventional PLL-based receiver, in which the latter could only track intermittently, especially during sharp turns. The produced carrier phase observables to 5 LTE eNodeBs in each region were fused with altimeter data via an extended Kalman filter (EKF) to estimate the aircraft's trajectory. Over trajectories of 51 km and 57 km in regions A and B, traversed in 9 min and 11 min, at flying altitudes of 5,000 and 7,000 ft above ground level, respectively, the proposed KF-based receiver reduced the position root-mean squared error (RMSE) by 74.8% and 30.7%, respectively, over the PLL-based receiver.