Algorithm and analysis of using GPS for a hybrid mobile satellite terminal

The air interfaces in acquiring GPS in the satellite Geo-Mobile-Radio -1 (Rel-3) (GMR-1 3G) and terrestrial 3GPP specifications are different, which raises a challenge for mobile terminals that are used in both networks. This paper discusses the algorithms and analysis of using GPS for such hybrid satellite terminals. We investigate the method of recovering the Keplerian parameters from Earth-centered-Earth-fixed (ECEF) coordinates. Two algorithms were studied. Algorithm 1 uses one position vector and one velocity vector, while algorithm 2 is based on two position vectors. Sensitivity analysis is presented to validate the proposed approach. Analysis and simulation show that the proposed transformation method provides effective and accurate performance and is suitable in bridging the satellite and terrestrial network specifications when acquiring GPS.