The ARWAAS is a Wide Area Augmentation System to be built around GPS constellation for improving the accuracy, integrity, and availability of the basic GPS signals over the ARab Countries region This system should allow UPS to be used as a primary means of navigation for en-route travel and for Category I approaches to selected airports throughout the region. This system would be extended to cover the Middle East region as well as most of the African continent. The system inherently should correct for ephemeris error (through satellite orbit estimation) and some other sources of errors.
In this paper, several techniques for GPS satellite orbit estimation (Non-dynamic, Kinematic, and Dynamic) for ephemeris error calculation are considered. Moreover, the problem of clock error estimation and reduction is investigated. A Least-Square algorithms developed for predicting the system performance under an initial layout for the ARWAAS so as to evaluate the anticipated performance.