Tracking performance of the coherent and noncoherent discriminators in strong multipath

Signal multipath leads to undesirable tracking errors and inaccurate ranging information for GPS receivers. The extent of the tracking error in compromising the receiver discriminator performance depends on the multipath amplitude, delay, and phase relative to the direct path. Compared with the rural area, the GPS receiver in the semi-enclosed area, such as city canyons and building shadows, is subject to much weaker line of sight propagation environment which further compromise its performance. In this paper, we derive analytical expressions of the multipath effect on the GPS tracking errors for both coherent discriminator and noncoherent early-minus-late power discriminators in strong multipath environment.