Mitigation of GPS Multipath Using Affine Combination of Two LMS Adaptive Filters

Global Positioning System (GPS) is an all weather Position, Velocity and Time determination navigation system. Multipath is one of the prominent error sources in GPS. In this paper, various Least Mean Square (LMS) adaptive algorithms such as simple LMS, Normalized LMS, Variable length LMS and affine combination of two LMS filters are investigated to mitigate multipath error. Accurate step size parameter is estimated and the performance of each filter is examined critically. Affine combination of two LMS adaptive filters uses two step sizes, one for slower convergence and another for good steady state response. The results are encouraging with affine combination of two LMS filters. It has improved performance with higher computational complexity compared to other three filters. Hence, affine combination of two LMS adaptive filters is the choice best choice for multipath mitigation in GPS applications.