Overcoming Ionospheric Scintillation for Worldwide Gps Aviation a Dissertation Submitted to the Department of Aeronautics and Astronautics and the Committee on Graduate Studies of Stanford University in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy

Together, the Global Positioning System (GPS) and the Wide Area Augmentation System (WAAS) can guide aircraft down to 200 ft above the runway. This approach procedure is referred to as Localizer Performance with Vertical guidance (LPV)-200. Approach guidance using GPS and WAAS has many advantages over traditional precision approach guidance using the Instrument Landing System (ILS) and the number of published LPV approaches in the U. S. is now greater than the number of published Category I ILS approaches. Given the success of LPV service in the U. S., worldwide expansion of the LPV service is being actively pursued. One of the main challenges for the LPV service in the equatorial area, including Brazil and India, is ionospheric scintillation. Due to electron density irregularities inside the ionosphere, transionospheric radio waves interfere constructively and destructively; consequently, a GPS receiver can experience deep and frequent signal fading. This phenomenon is known as ionospheric scintillation. Although the physics of the ionospheric scintillation has been studied for several decades, its impact on GPS aviation has not been well understood. As a result, the current GPS aviation receiver performance standards (RTCA/DO-229D) do not have any specific performance requirements to mitigate the impact of scintillation. Although current aviation receivers do not protect against scintillation, currently it