Multipath Estimation in Multicorrelator GNSS Receivers using the Maximum Likelihood Principle

This paper proposes a multipath mitigation technique for multicorrelator Global Navigation Satellite System (GNSS) receivers that estimates the line-of-sight (LOS) and the multipath signal parameters in a computationally efficient manner. The maximum likelihood (ML) principle is applied leading to a nonlinear optimization problem. A closed-form solution of the nonlinear estimation problem is proposed where the estimation of the LOS delay is performed using a grid search approach. Lack of convergence, initialization, and computational complexity problems are avoided and a small computational burden is achieved. A low-complexity complementary method based on interpolation is proposed in order to increase the resolution of the estimated delay with respect to the limit set by the correlators´ spacing. Theoretical performance and limits are determined considering that the delay is estimated through a grid search approach and the observations are obtained in the presence of nonwhite Gaussian noise due to the correlation between samples.