Abstract: The present invention overcomes the limitations encountered by conventional packet switching using virtual circuits. The present invention utilizes a "datagram" approach that routes every packet (22) conveyed by the system independently at every node in the network. The packets (22) are directed along an optimized pathway through the network by a fast packet switch (38) that directs traffic based on instructions from an adaptive routing processor (12A) that continuously runs an adaptive routing software (12B). This adaptive routing processor (14) supplies an output (12C) to a routing cache memory (20) which stores fast packet switch routing port output tags (30). An input packet processor (28) extracts a supercell address from the header (24) of each packet (22) and uses the supercell address (21A) as an index to retrieve a fast packet switch output port tag (30) stored in the routing cache memory (20).

Abstract: Methods and apparatus which route, control and manage traffic throughout a Satellite Communication System operating in low Earth orbit are disclosed. Voice, video and data traffic from terrestrial gateways (G) and from portable (P), mobile (M) or fixed (F) terminals are directed up through the constellation of satellites (S) and back down to destinations on Earth. The satellites provide continuous worldwide communication services while insuring uniform end-to-end transmission delays. The satellite network is highly adaptive to the constantly changing network topology, and will offer a synchronous circuit switched communication service that provides sequential delivery of user data, regardless of the type of the data transmitted. The network employs datagram switching, as opposed to conventional virtual circuit switching techniques.

Abstract: Earth-fixed cell beam management methods which may be employed to allocate beams generated by a constellation of low Earth orbit satellites (12) flying in orbits below geosynchronous altitudes are disclosed. These beams (19) are electronically steered so that they illuminate "Earth-fixed cells" (26) as opposed to "satellite-fixed cells." Beam steering apparatus using a spherical dielectric lens (106) is disclosed. In a system that employs satellite-fixed cells, the "footprint" of the beams propagated by a spacecraft defines the zone on the ground called a "cell" which is illuminated by the spacecraft. This satellite-fixed cell moves constantly as the spacecraft moves around the globe. In sharp contrast, an "Earth-fixed cell" (26) is a stationary region mapped onto the surface of the Earth (E) that has permanent fixed boundaries, just like a city or a state.

Abstract: Terrestrial antennas (10A, 10B, 10C and 10D) which are capable of transmitting and receiving radio signals directly to and from satellites in low Earth orbit are disclosed. The preferred embodiment of the invention employs circularly polarized, dual-frequency printed circuit antenna elements (136) measuring only a fraction of an inch in diameter. One embodiment (10A) includes an elevation array and an azimuth array which both reside on a trapezoidal, semi-conical housing that resembles a flattened pyramid. Both the top and the curved exterior of the pyramid support circular, slotted, printed circuit patches on their surfaces which bound individual radiating antenna elements (18). Since the entire antenna is only a few inches in diameter and is less than two inches high, it can be incorporated as an integral element of a telephone (T) or can be mounted at the end of a collapsible mast (CM).

Abstract: An advanced active element phased array satellite antenna is disclosed. Incorporating these novel antenna systems on a constellation of low Earth orbit spacecraft, allows phone customers worldwide to communicate through a system whose switching intelligence resides on orbit, bypassing traditional land-based networks, and offering a revolutionary expansion of communications potential. The present invention utilizes electronic beam steering is utilized to provide extremely high gain signals. In one preferred embodiment, a satellite (S) includes an Earth-facing array (10) of hexagonal antenna facets (12), mated together along their sides to form a slightly flattened, hemispherical shell. The antenna array (10) is connected to two rectilinear, unfurled, solar panels (P). The antennas (10) transmit and receive signals from terrestrial units located within the footprints (14) of the beams (11).

Abstract: A series of spacecraft designs (10, 42 and 52) for a Satellite Communication System is disclosed. One of the preferred embodiments of the invention called "Gearsat.TM." (10) comprises a hollow torus which inflates when it reaches orbit. When viewed from the side along its circumference, Gearsat (10) looks like two flattened pyramids sharing a common base. Phased array antenna panels (14) are deployed across the top of the pyramid along an exterior cylindrical surface (12), while twin arrays of solar cells (16) cover the slanted surfaces. The satellite (10) rotates about its center, and individual antenna panels (14) are spatially synchronized to transmit and receive signals from particular regions on the ground. An alternative embodiment, called "Batsat.TM." (42, 52), includes a central cylindrical body (B) and a plurality of substantially circular linked antenna and solar/thermal panels (A1-A9 and S1 and S2) which carry individual antennas (X) and solar/thermal surfaces (Y).

Abstract: Methods for transmitting and receiving radiated energy (15a, 15b, 15c) from and to a satellite (12) which moves with respect to the Earth's surface are disclosed. The invention pertains to any satellite (12) which is not in an equatorial orbit at geosynchronous altitude. The present invention reduces hand-off overhead in systems that utilize satellite-fixed cells, augments frequency re-use, and enhances the communications and sensing capacity of the satellite. In accordance with the methods of the invention, satellite footprints (16a, 16b, 16c) are partitioned into linear spanning cells (18) and multiple linear segments (22). The linear spanning cells (18) resemble long strips that extend across an entire footprint (16a, 16b, 16c). Multiple linear segments (22) are smaller contiguous areas that lie within the linear spanning cells (18). The alignment of the linear spanning cells (18) across a footprint (16a, 16b, 16c) is determined by a correction angle .phi.

Abstract: A method and apparatus for providing a plurality of beams (30) transmitted and received from positions in low Earth orbit (11) for communicating directly with a plurality of portable, mobile and fixed terminals and gateways is disclosed. A plurality of scanning beam antennas (28) is deployed on each satellite (12) within a constellation (10) of satellites placed in low Earth orbit (11). Each one of said plurality of scanning beam antennas (28) simultaneously receives and transmits a plurality of beams (30), each of which beams (30) illuminates cell (26) in an Earth-fixed grid (20). The beams (30) are formed by each scanning beam antenna (28) and are focused on the cell (26) by a dielectric lens (60). A preferred embodiment uses a Luneberg spherical lens (60). Each beam (30) is electronically shaped and steered to keep the cell (26) of the Earth-fixed grid (20) within the beam footprint (50).

Abstract: A Modular Communication Satellite (10) for a Satellite Communication System is disclosed. The preferred embodiment of the invention includes a foldable, high-gain, electronically steered antenna array (12) that is always pointed toward the Earth (E). The unfolded spacecraft resemble an oblate flower. Polygonal antenna panels (92, 94, 96, 102, 104, & 106) are attached to each other and to a primary bus structure (22) by antenna deployment hinges (90). The upper portion of the satellite (10) incorporates intersatellite antenna arrays (26) of individual intersatellite antennas (28), which are always pointed tangentially to the Earth (E). An Astromast.TM. boom (32) is mounted between the space facing surface of the primary bus structure (22) and an assembly of solar array storage booms (36). The Astromast.TM. boom (32) can expand and rotate amorphous silicon solar arrays (38) which are unfurled from within the solar array storage booms (36).

Abstract: Earth-fixed cell beam management methods which may be employed to allocate beams generated by a constellation of low Earth orbit satellites (12) flying in orbits below geosynchronous altitudes are disclosed. These beams (19) are electronically steered so that they illuminate "Earth-fixed cells" (26) as opposed to "satellite-fixed cells." In a system that employs satellite-fixed cells, the "footprint" of the beams propagated by a spacecraft defines the zone on the ground called a "cell" which is illuminated by the spacecraft. This satellite-fixed cell moves constantly as the spacecraft moves around the globe. In sharp contrast, an "Earth-fixed cell" (26) is a stationary region mapped onto the surface of the Earth (E) that has permanent fixed boundaries, just like a city or a state.