Experimental Performance of a Cellular LTE and GPS Vector Tracking Receiver

Samuel Morgan, J. Tanner Koza, Scott Martin

Peer Reviewed

Abstract:	This paper presents simulated and experimental results of a combined Vector Delay/Frequency Locked Loop (VDFLL) for tracking GPS and Long-Term Evolution (LTE) signals together. To enable the VDFLL Extended Kalman Filter (EKF), the openloop pseudorange and pseudorange rate variance calculations in terms of C/N0 are provided. Then, a method of calculating C/N0 using the correlator outputs from the Cell-specific Reference Signal tracking loop is given. Monte Carlo simulations are performed under a number of conditions, including multipath fading and eNodeB localization errors. It is shown that including LTE signals in the VDFLL improves GPS code phase tracking when multipath is minimal and the position of the eNodeB is well known but does not improve LTE code phase tracking. It is also shown that when multipath is harsh and/or only a coarse estimate of the eNodeB position is known, GPS code phase tracking may degrade. Monte Carlo simulations are also performed to examine the performance of the combined VDFLL during GPS outages. These simulations show that by including LTE signals, regardless of multipath or eNodeB localization error, the probability of tracking over outages during static and dynamic tests increased by up to 75% and 30% over the GPS-only VDFLL static and dynamic simulations, respectively. Finally, static and dynamic experimental tests are conducted and the combined VDFLL is tuned to combat the limited knowledge of the eNodeB’s position. The 3D root mean squared error of the combined VDFLL improved 34% and 15% for the static and dynamic tests, respectively when compared with the GPS-only VDFLL.
Published in:	Proceedings of the 36th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2023) September 11 - 15, 2023 Hyatt Regency Denver Denver, Colorado
Pages:	2404 - 2418
Cite this article:	Morgan, Samuel, Koza, J. Tanner, Martin, Scott, "Experimental Performance of a Cellular LTE and GPS Vector Tracking Receiver," Proceedings of the 36th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2023), Denver, Colorado, September 2023, pp. 2404-2418. https://doi.org/10.33012/2023.19245
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