A study on GPS augmentation using Japanese Quasi-Zenith Satellite System

The current GPS satellites constellation provides limited availability and reliability for the country like Japan where mountainous terrain and urban canyon does not allow the wide skyline. At present, Japanese Quasi-Zenith Satellite System (QZSS) is planned under government-private sector cooperation. QZSS is considered as a multi-mission satellite system, it is able to provide communication, broadcasting and positioning services for mobile users in specified region with high elevation angle. The performance of a Global Navigation Satellite System (GNSS) can be quantified by availability, accuracy, reliability and integrity. The additional GPS compatible signal from QZSS can remarkably improve the availability, accuracy, reliability and integrity of GPS positioning. This paper focuses on the performance of GPS augmentation using QZSS in Japan and its neighboring areas. The constellation and signal structure of QZSS are briefly introduced. The measures for performance evaluation are described. The availability, accuracy, reliability and capability of carrier phase based positioning of GPS augmentation using QZSS are obtained by software simulation. The simulation results are presented using the number of visible satellites as a measurement of availability, Geometrical Dilution of Precision as a measure of accuracy and minimal detectable bias as a measure of reliability and ambiguity success rate as a measure of capability of carrier phase based positioning, with spatial and temporal variation. It is shown, that QZSS will not only improve the availability and accuracy of GPS, but also enhance the system reliability and the capability of carrier phase based positioning in Japan and its neighboring areas.