METHOD AND SYSTEM FOR MOBILE DEVICE BASED GNSS POSITION COMPUTATION WITHOUT EPHEMERIS DATA

摘要

A GNSS enabled mobile device receives GNSS assistance data comprising acquisition assistance data, from an A-GNSS server and calculates a relative GNSS position using the receive acquisition assistance data and a local code delay measurement, without using ephemeris data. The received GNSS assistance data comprises an approximate position, acquisition assistance data, satellite almanac data, and/or satellite azimuth and elevation fields, but no ephemeris data. The A-GNSS server calculates corresponding acquisition assistance data at a current time instant and/or one or more future time instants for the approximate position. The satellite azimuth and elevation fields are calculated using local GNSS measurements together with the acquisition assistance data in the received GNSS assistance data are used to calculate the relative GNSS position, which is added to the approximate position to generate an actual GNSS position.