  Opportunistic navigation using cellular signals is appealing for scenarios
where other navigation technologies face challenges. In this paper, long-term
evolution (LTE) downlink signals from two neighboring commercial base stations
(BS) are received by a massive antenna array mounted on a passenger vehicle.
Multipath component (MPC) delays and angle-of-arrival (AOA) extracted from the
received signals are used to jointly estimate the positions of the vehicle,
transmitters, and virtual transmitters (VT) with an extended fast simultaneous
localization and mapping (FastSLAM) algorithm. The results show that the
algorithm can accurately estimate the positions of the vehicle and the
transmitters (and virtual transmitters). The vehicle's horizontal position
error of SLAM fused with proprioception is less than 6 meters after a traversed
distance of 530 meters, whereas un-aided proprioception results in a horizontal
error of 15 meters.
