Advanced concepts in global navigation satellite systems (GNSS) such as the American GPS (global positioning system), the European’s Galileo and the Russian’s GLONASS (GLObal Navigation Satellite System) System level description, architecture and design of a wide area augmentation system (WAAS) comprising geostationary satellites overlaying GPS satellites and its vast network of monitoring and control ground stations. The equivalent EGNOS (European Geostationary Navigation Overlay Service), a precursor to Galileo and the Japanese MSAS (Multi-transport Satellite-based Augmentation System) Updates on evolving GNSS technology and GNSS backup alternatives.