Patent ID: 8700322
Filing Date: 2014-04-15
Classification: G01S

Abstract:
1. A method for computing a position of a mobile station, the method comprising: storing at least one predetermined portion of an expected user altitude database in the mobile station; accessing a global elevation estimate; estimating an initial position of the mobile station based on the global elevation estimate and at least three global positioning system satellite measurements; identifying a first selected area in the stored at least one predetermined portion of the expected user altitude database based on the estimated initial position, the first selected area based on and including the estimated initial position; determining an altitude estimate from the initial position of the mobile station, and the at least one predetermined portion of the expected user altitude database, wherein the expected user altitude database includes at least two assumed altitude levels for the mobile station associated with at least a subset of coverage areas included in the expected user altitude database, and wherein determining the altitude estimate for the subset of coverage areas includes selecting an assumed altitude level from the at least two assumed altitude levels based at least in part on the velocity of the mobile station; and calculating the position of the mobile station.