Tracking performance and average error analysis of GPS discriminators in multipath

Signal multipath in GPS leads to undesirable tracking errors and inaccurate ranging information. The extent of the tracking error in compromising the receiver performance depends on the multipath amplitude, delay, and phase relative to the direct path. The coherent discriminator and the noncoherent early-minus-late power discriminator offer different tracking accuracy and sensitivity to multipath parameters. In this paper, we develop analyses of the effect of multipath carrier phase offset on GPS tracking error bounds as well as statistical average error values. Although the two receiver discriminators share the same performance bounds, they differ in their response to the multipath within these bounds. The analytical expressions for this response provide the framework to assess the average performance of the two discriminators over the multipath phase distribution and other important propagation channel variables.