 To study the ionospheric behaviour more effectively over entire Indian airspace, Indian universities and R&D labs, which are involved in the development of regional based ionotropic model for GAGAN, have suggested nine more TEC stations.GAGAN is now in operational phase and is compatible with other SBAS systems such as the wide-area augmentation system (WAAS), the European Geostationary Navigation Overlay Service (EGNOS) and the Multi-functional Satellite Augmentation System (MSAS) and will provide seamless air navigation service across regional boundaries.While the ground segment consists of eight reference stations and a master control center, which will have sub systems such as data communication network, SBAS correction and verification system, operations and maintenance system, performance monitoring display and payload simulator, Indian land uplinking stations will have dish antenna assembly.