Communication system employing spectrum reuse on a spherical surface
First Claim
1. A method of operating first and second spaced apart antennas, said first and second antennas projecting first and second footprints, respectively, said first and second footprints each being divided into a plurality of cells, said method comprising the steps of:
- positioning said antennas so that said first and second footprints overlap;
defining said cells of said footprints as being active or inactive in response to said overlap; and
assigning channels to said active ones of said cells of said first and second footprints in accordance with a spectrum reuse plan that maintains a minimum predetermined separation distance between co-channel cells.
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0 Petitions
Accused Products
Abstract
Orbiting satellites project footprints on the earth. Each footprint is divided into cells. Footprints of nearby satellites overlap one another, and the overlap increases as satellites approach a pole from the equator. The positions of all cells generated by all satellites are simulated at numerous points throughout an orbit. Cells are marked as being active or inactive to compensate for the overlap at each simulated point. Channel sets are assigned to cells within a reference footprint, and this assignment is propagated throughout all footprints in the referenced footprint'"'"'s orbit. The channel set sequences are propagated to other orbits after taking into account inactive cells located near boundaries between the orbits. Each satellite stores channel set assignments for its cells at the various points throughout its orbit. All satellites switch their communication parameters at the same instant in response to the channel set assignments.
123 Citations
20 Claims
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1. A method of operating first and second spaced apart antennas, said first and second antennas projecting first and second footprints, respectively, said first and second footprints each being divided into a plurality of cells, said method comprising the steps of:
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positioning said antennas so that said first and second footprints overlap; defining said cells of said footprints as being active or inactive in response to said overlap; and assigning channels to said active ones of said cells of said first and second footprints in accordance with a spectrum reuse plan that maintains a minimum predetermined separation distance between co-channel cells. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A communication system which has an area of coverage directed to an approximately spherical surface and which reuses a given amount of spectrum throughout said area of coverage, said system comprising:
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a first antenna configured to project a first footprint on said surface, said first footprint being divided into a plurality of cells; a second antenna configured to project a second footprint on said surface, said second footprint being divided into a plurality of cells, and said second footprint overlapping at least a portion of said first footprint at least on occasion; a first transceiver coupled to said first antenna; a second transceiver coupled to said second antenna; a first memory coupled to said first transceiver and configured to store a first set of channel-to-cell assignments; and a second memory coupled to said second transceiver and configured to store a second set of channel-to-cell assignments, said first and second memories being configured so that said first and second sets of assignments control allocation of said spectrum to said first and second transceivers, respectively, to maintain a predetermined separation distance between co-channel cells. - View Dependent Claims (8, 9, 10, 11)
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12. A method of reusing spectrum on an approximately spherical surface, said method comprising the steps of:
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(a) simulating locations for first and second footprints projected on said surface from corresponding first and second antennas positioned outside said surface, each footprint being divided into a plurality of cells, and said first and second footprints at least partially overlapping one another; (b) assigning channels of said spectrum to said first footprint cells in accordance with a spectrum assignment plan that spaces co-channel cells a predetermined distance apart; (c) defining active and inactive cells, said inactive cells being located proximate a boundary between said first and second footprints to compensate for overlap therebetween; (d) assigning channels of said spectrum to said active cells of said second footprint, said step (d) being responsive to said active cells assigned in said step (b) and to said inactive cells defined in said step (c) to maintain separation between active co-channel cells; and (e) communicating through said antennas in accordance with said assignments of said channels to said active cells in said first and second footprints. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20)
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Specification