If the measurements of the EKF are more than four, then the variance of the dynamic stress error and oscillator noise error will be decreased which is similar to a vector delay lock loop
(VDLL) [10, 11].
Townsend, "The multipath estimating delay lock loop
: approaching theoretical accuracy limits", in Proc.
The DesignWare DDR multiPHY is architected for extremely low power consumption and features Delay Lock Loop
(DLL) bypass modes for operation below 200 MHz.
The multipath estimating delay lock loop (MEDLL)  algorithm was proposed based on the maximum likelihood (ML) estimation.
GNSS: Global Navigation Satellite System DLL: Delay lock loop PPE: The PRN code phase error GPS: Global positioning system MEDLL: Multipath estimating delay lock loop MMT: Maximal measurement tree RHCP: Right-hand circular polarization LHCP: Left-hand circular polarization Conflicts of Interest
Townsend, "Multipath estimating delay lock loop: approaching theoretical accuracy limits," in Proceedings of the IEEE Position Location and Navigation Symposium, pp.
Then the multipath can be detected from residual signal by the regular delay lock loop (DLL).
The code tracking loop in the GPS receiver is a delay lock loop (DLL) called an early-late tracking loop .