low-orbit satellite communications system with radio-satellite satellites

摘要

Low-orbiting satellite communication system with radiofrequency satellites characterized by the presence of two types of satellites: a first type, satellites of communication with the user, with unique function and of making the outgoing or returning links to the end user and of communicating with the radio satellites, and a second type, the radio satellites, with the function of repeating the signal from the user's communication satellites towards the satellite base stations of the satellite system (gateways or transit stations) that will connect the user with the pre-existing fixed network. the radio satellite may or may not accumulate the function of satellites communicating with the user. the two types of satellites, radios and user communication, orbit two satellite constellations for different purposes. The constellation of user communication satellites is intended to provide visibility to regional or global coverage regions on the planet's surface. The constellation of radiofrequency satellites is designed to provide permanent visibility between the two types of satellites. The system will employ a larger number of user communication satellites than radios and may provide fixed or mobile telecommunications services. This system incorporates concepts from both the scientific tdrs tracking and data relay satellites systems and the current proposed satellite systems in non-geostationary orbits, the descriptions of which can be obtained from the International Union of Radiocommunication Bureau's weekly circulars. telecommunications. the main difference with respect to tdrs is the use of individually fixed radio coverage beams with respect to satellites, and the switching of beams employed by both the user communication satellite and the radio satellite to establish a traffic link between them instead of the satellite. use of self-tracking beams dedicated to each satellite throughout its visibility period. in the coverage of the beams of the radios that allow continuous visibility by at least one radiofrequency satellite and any of the communication satellites with the user. The main difference from the proposed non-geostationary telecommunications satellite concepts is in the inclusion of radiofrequency satellites: repeater satellites use an individually fixed radio-coverage multi-beam antenna and channel and beam switching to efficiently serve a number. satellites of communication with the user, treating them identically, with respect to coverage, to what the present mobile satellite do to the user, and not antennas of variable radio coverage, for the purpose of tracking and linking dedicated to a specific satellite as in tdrs. The proposed system treats as a channel for switching purposes a group with a significant part or even the entire set of individual user channels of the same beam over a broadband band (for example a multi-channel cdma carrier). With this concept, on-board switching operates a low number of high bandwidth channels, and is much simpler than that of individual on-board switching systems, no longer a considerable cost in satellite design, and failing to affect its reliability. communications supporting the system ground network, where appropriate, prevent the user communications satellite from sending information concerning one of its beams to more than one radio satellite. Energy savings and efficient use of the spectrum will be ensured by verifying the presence of the satellites communicating with the user by the repeating satellites and vice versa, only sending transmission to the beams in the event of correct positioning, ground clearance or presence of signal, and agreement of the system manager. The introduction of the radio-satellite allows lower user communication satellites to be used, facilitating frequency reuse and increasing total communications capacity without the need for an extremely dense network of transit stations or complex switching schemes. satellites and interconnection between satellites present in low orbit systems, where all satellites have the same functions. The use of two independent satellite constellations allows the optimum altitude of the orbit associated with the respective functions of the pass-through or radio-repeat satellites and end-user communication satellites.