Satellite-based cellular telecommunications system utilizing an earth station subsystem

The present invention includes a satellite based telecommunications system having an earth station network which enables user terminals to remain registered with a single visitor location register independent of satellite movement so long as the terminal remains within a fixed geographic location area. The preferred embodiment includes multiple earth stations which communicate with user terminals via coverage satellites. Each user terminal is registered with a single visitor location register. As the user passes between location areas, the user terminal re-registers at a new associated visitor location register. Earth stations and mobile-services switching center/visitor location registers (MSC/VLRs) are interconnected along a dedicated earth station network link. Communications data is passed along the earth station network link between MSC/VLRs and earth stations in a compressed and/or encoded format. Each MSC/VLR is interconnected along a terrestrial network link with a gateway and the public switching telephone network. Communications data is passed along the terrestrial network link in a decompressed and/or decoded format. Optionally, MSC/VLRs may be located physically remote from earth stations. When MSC/VLRs and earth stations are provided at a common physical site, a modem switch is provided to selectively interconnect the earth station and MSC/VLR and the earth station network link. Earth stations and MSC/VLRs communicate along the earth station network through wide area network interfaces.