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US 5,668,556 AGranted
Low-orbit satellite communications system for terminals
AssigneeAlcatel Espace
InventorsDenis Rouffet, Frederic Berthault, Michel Mazzella, Yannick Tanguy
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Abstract
The present invention relates to a communications system between low-orbit satellites and terminals, in which the beams (12) of each service area (14) are illuminated according to a beam-hopping spatial scanning. For each satellite and for each terminal transmission and reception are separated in time and synchronized. Time-division duplex is used. Applicable especially to the field of space telecommunications.
Claims26
A communications system, comprising:
- low-orbit satellites, each of said satellites providing ground coverage over respective service areas by using a plurality of radiation beams;
- and
- a plurality of ground terminals, located within said service areas, and communicating with said satellites over respective links;
- wherein the beams of each of said service areas are switched on in accordance with a beam-hopping technique;
- wherein transmission and reception, for each of said plurality of ground terminals and each of said low-orbit satellites communicating over each of said respective links, are (1) synchronized and (2) separated in time;
- wherein an identical frequency band is used for said transmission and said reception;
- and
- wherein time-division duplex is utilized for each of said respective links.
5 more elements
A communications system, comprising:
- low-orbit satellites, each of which (1) provides ground coverage over respective service areas by using elliptical radiation beams elongated in a satellite direction of passage, and (2) comprises a communications antenna system that ensures uniform flux coverage through said beams;
- ground terminals, located within said service areas, and communicating with said satellites over respective links;
- and
- an interconnection earth station comprising means for tracking and controlling the synchronization of said respective links;
- wherein the beams of each of said service areas are switched on in accordance with a space diversity beam-hopping technique;
- wherein a ground footprint of each of said beams forms a respective cell of said communications system;
- wherein transmission and reception, for each of said ground terminals and each of said satellites communicating over each of said respective links, are (1) synchronized and (2) separated in time;
- wherein an identical frequency band is used for said transmission and said reception;
- and
- wherein time-division duplex is utilized for each of said respective links.
7 more elements
Dependencies are inferred from the claim text.