Earth station acquisition system for satellite communications

A method for use in a satellite communication system where a user terminal is operable to communicate with a plurality of satellites;

• where each of said plurality of satellites is operable to communicate with each of a plurality of earth stations;
• where said user terminal is operable to communicate through said plurality of satellites to request service;
• where said plurality of earth stations comprises a controller;
• said method including:
• each of said plurality of earth stations monitoring said satellites;
• each of said plurality of earth stations, in the event of receiving a request for service from said user terminal, calculating the position of said user terminal, providing said calculated position of said user terminal and signaling to said controller, indicatively of having received a request for service from said user terminal and with said calculated position, in response to said receipt of a signal indicative of having received a request for service from said user terminal, instructing the best placed one of said plurality of earth stations to service said request and to provide a gateway for call traffic based on said calculated position of said user terminal.

A user terminal for use in a satellite communication system where said user terminal is operable to communicate with each of a plurality of satellites;

• where each of said plurality of satellites is operable to communicate with each of a plurality of earth stations;
• where said user terminal is operable to communicate through said plurality of satellites to request service;
• where said plurality of earth stations comprises a controller;
• where each of said plurality of earth stations is operable to monitor said satellites, and in the event of receiving a request for service from said user terminal, calculating the position of said user terminal and providing said calculated position of said user terminal and signaling said controller, indicatively of having received a request for service from said user terminal, to instruct the best place one out of said plurality of earth stations to service said request based on said calculated position of said user terminal;
• said user terminal being characterized by being operable to store the identity of that earth station whereat said user terminal was last registered and to convey said identity to said controller and is further operable, in the event of said user terminal not storing an identity, to accept, as said identity, the identity of said best placed earth station.