Multipath Mitigation Using Linear Adaptive Filtering Techniques

Linear adaptive filters result to be suitable to treat the Global Navigation Satellite System (GNSS) multipath channel, given that the signal affected by multipath results as a weighted sum of delayed replicas of a same signal. Since the multipath is becoming more and more one of the limiting factor of the GNSS performance, the problem of its detection and mitigation is one of the most discussed topics in literature. In thi paper a linear adaptive filter, in particular, a Least Squares (LS) filter is applied in post-correlation to a Global Positioning System (GPS) signal. The aim is to find an estimate of the distortion introduced by the multipath on the correlation function, in order to correct the code-delay estimate. Moreover, an analysis is done in order to study the effects of the number of samples in the correlation function. In fact the more correlators are considered, the higher accurate the estimate can be, but the higher the computational effort is required. The aim of this analysis is therefore to find a trade-off in terms of performance and complexity. The proposed estimation method is presented and simulation results are shown, where the GPS data are simulated with a signal simulator.