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International Journal of Aerospace Engineering
Volume 2015, Article ID 165178, 8 pages
http://dx.doi.org/10.1155/2015/165178
Research Article

ARMA Prediction of SBAS Ephemeris and Clock Corrections for Low Earth Orbiting Satellites

School of Aerospace and Mechanical Engineering, Korea Aerospace University, Goyang 412-791, Republic of Korea

Received 17 March 2015; Revised 21 May 2015; Accepted 2 June 2015

Academic Editor: Paolo Tortora

Copyright © 2015 Jeongrae Kim and Mingyu Kim. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

For low earth orbit (LEO) satellite GPS receivers, space-based augmentation system (SBAS) ephemeris/clock corrections can be applied to improve positioning accuracy in real time. The SBAS correction is only available within its service area, and the prediction of the SBAS corrections during the outage period can extend the coverage area. Two time series forecasting models, autoregressive moving average (ARMA) and autoregressive (AR), are proposed to predict the corrections outside the service area. A simulated GPS satellite visibility condition is applied to the WAAS correction data, and the prediction accuracy degradation, along with the time, is investigated. Prediction results using the SBAS rate of change information are compared, and the ARMA method yields a better accuracy than the rate method. The error reductions of the ephemeris and clock by the ARMA method over the rate method are 37.8% and 38.5%, respectively. The AR method shows a slightly better orbit accuracy than the rate method, but its clock accuracy is even worse than the rate method. If the SBAS correction is sufficiently accurate comparing with the required ephemeris accuracy of a real-time navigation filter, then the predicted SBAS correction may improve orbit determination accuracy.