Personal mobile satellite communications

Project 21 is Inmarsat´s overall vision and strategy for the development of such systems from now into the 21st century. This paper describes the four main service elements of the programme: Inmarsat-C, a portable mobile satellite data service introduced in 1991; Inmarsat-M, a briefcase-sized digital satellite phone being introduced in the coming months; global satellite paging scheduled for service introduction in 1994; and Inmarsat-P, in planning for introduction in the 1998-2000 time-frame. The Inmarsat-P terminal is envisaged as a dual-mode terminal that will work with a cellular system or from the satellite when out of home region cellular coverage, or operating from a region with a different cellular standard or without roaming arrangements. The paper describes some of the system considerations that need to be further addressed in order to select the most optimal P-Sat system design