Multi-Frequency Kalman Filtering for Joint Ionospheric Delay and Multipath Mitigation

This paper tackles the problem of robust Global Navigation Satellite System (GNSS) ranging in the presence of ionospheric activity and multipath signals. We introduce a novel algorithm that fuses the incoming signals from different frequency bands and is able to separate the purely geometry dependent code phase delay from the ionosphere induced signal delay. Additionally, it performs simultaneous channel estimation and equalization of multipath signals. The proposed algorithm appears to be able to provide an unbiased code phase estimation with the estimation variance of the best from the signals used.