Calculated Distance Error Improvement by Using Elevation Mask in Relay Type GPS

In relay type GPS, target GPS receivers receiving directly less than 4 GPS satellite signals in an urban area can calculate their positions by assists of the many mobile terminals around them, which transmit their own positions via the GPS signal format. Therefore, the relay type GPS's calculated distance error performances are significantly affected by those of the mobile terminals transmitting GPS signals (G-MTs) around the target GPS receivers. In this paper, a new relay type GPS applying elevation mask to G-MTs is proposed to improve the calculated distance error performances of the target GPS receivers. The simulation results indicate the proposed relay type GPS with elevation mask improves the calculated distance error performances compared to those of the conventional one. For example, by applying elevation mask of 7 degrees to G-MTs, the proposed scheme obtains 3.62m improvement of the 24 hours average calculated distance error.