Evaluation of Positioning Performance using the GPS + QZSS in Shanghai

Abstract

The Global Position System (GPS) may have poor performance in metropolitan areas where there is a terrible blocking effect for satellite signals. A different positioning system combination will increase the number of visible satellites and enhance the strength of the satellite geometry. The Japanese Aerospace Exploration Agency (JAXA) confirmed that the first quasi-zenith satellite (QZS) ''MICHIBIKI'' began providing positioning signals on June 22, 2011 (JST). The QZS system (QZSS) can provide compatible signals and has a better interoperability with GPS. Therefore, we used integration of the two systems to verify the changes in positioning performance. To demonstrate the positioning accuracy of the proposed methods, evaluations of the positioning performance using only the GPS system and the GPS + QZSS system are conducted using real observation data in Shanghai. Three indicators are used to evaluate the positioning performance: the number of visible satellites (NVS), position dilution of precision (PDOP), and root mean square (RMS). Meanwhile, the results show that GPS augmentation using the QZSS improves the positioning performance for high elevation mask angles. Positioning availability increases more than 30% at 45 degrees, and by as much as 64% on day 3. The performance is more stable using the GPS + QZSS.