In the third generation of mobile systems several satellite systems, each tailored to specific user requirements are expected to be integrated with the terrestrial cellular network. This article deals with the extension to satellite systems of the advanced networking concepts which are emerging in the third-generation framework. In particular, it focuses on the basic functional areas for mobile satellite systems, namely, the cell and the location area. It is worth stressing that proper definitions of the satellite cell and satellite location area concepts, as well as an appropriate design of the satellite cell and satellite location area layouts, are essential, since the mobility procedures (cell reselection, paging, localization, handover) make systematic reference to these concepts. The topics exposed in this article are applicable to any satellite system regardless of orbit type, from geostationary (GEO) to low Earth orbits (LEO): the satellite spot-beam arrangement, access technique, and on-board switching capabilities (ranging from transparent payloads with reduced switching capabilities to satellite systems provided with on-board processing capabilities and intersatellite link).