Satellite communication system providing multi-gateway diversity to a mobile user terminal

A satellite communication system comprising a plurality of terrestrial gateways, at least one user terminal, and a plurality of satellites forming a constellation of non-geosynchronous satellites, said system further comprising:

• circuitry in a first gateway for bidirectionally coupling said first gateway to a first terrestrial telecommunications network and circuitry for bidirectionally coupling said at least one user terminal to said first terrestrial telecommunications network through at least one satellite of said constellation of satellites;
• an inter-gateway communications link bidirectionally coupled between said first gateway and a second gateway without passing through any of said satellites of said constellation of satellites;
• and
• further circuitry in said first gateway, coupled to said inter-gateway communications link, for coupling said at least one user terminal to said first terrestrial telecommunications network via said first gateway, said inter-gateway communications link, said second gateway and through said at least one satellite or through at least one further satellite of said constellation of satellites;
• wherein said inter-gateway communications link communicates call-related information between said first gateway and said second gateway.

In a satellite communications system comprising a plurality of gateways and a plurality of satellites forming a constellation of non-geosynchronous satellites, a method for providing a gateway with a larger effective terrestrial coverage area, comprising steps of:

• providing a first gateway and a second gateway, each gateway having an associated terrestrial coverage area and each gateway being coupled to a different terrestrial telecommunications network;
• providing an inter-gateway communications link bidirectionally coupled between said first gateway and said second gateway, said inter-gateway communications link being provided so that it does not pass through any of said satellites of said constellation of satellites;
• establishing a call connection between a first terrestrial telecommunications network coupled to the first gateway and a user terminal located in the terrestrial coverage area of the first gateway by coupling the user terminal to the first telecommunications network via at least one satellite that is in view of the first gateway and the user terminal;
• and
• while the call connection is established, further coupling the user terminal to the first terrestrial telecommunications network via the second gateway, the at least one satellite or at least one further satellite that is in view of the second gateway and the user terminal, an inter-gateway communications link and the first gateway, said step of further coupling comprising a step of exchanging call-related data between the first gateway and the second gateway over said inter-gateway communications link.

A method for operating a satellite communication system comprising a plurality of gateways, at least one user terminal, and a plurality of satellites forming a constellation of non-geosynchronous satellites, comprising steps of:

• establishing a call connection between a terrestrial telecommunications network and the user terminal via a first gateway and at least one satellite;
• and
• while the call connection is established, communicating call-related information between the first gateway and a second gateway through an inter-gateway communications link that bidirectionally couples the first gateway to the second gateway without passing through any of the satellites of the constellation of satellites for coupling the user terminal to the terrestrial telecommunications network via the second gateway, the inter-gateway communications link, the first gateway, and through the at least one satellite or through at least one further satellite,
• wherein the step of coupling is performed in response to the at least one satellite or the at least one further satellite exhibiting a better signal quality, relative to the user terminal, than a signal quality obtained using the at least one satellite and the first gateway;
• wherein the step of coupling includes a step of conveying call speech or data information between the first gateway and the second gateway.