Method and system of efficient spectrum utilization by communications satellites

• US 6,810,249 B1
• Filed: 09/19/2000
• Issued: 10/26/2004
• Est. Priority Date: 09/19/2000
• Status: Expired due to Term

• Current Assignee: DIRECTV, LLC (AT&T, Inc.)
• Original Assignee: The DIRECTV Group, Inc. (AT&T, Inc.)
• Inventors: Stone, Adam, Walsh, Thomas M., Hrycenko, George, Nunan, William J.
• Primary Examiner(s): Maung, Nay
• Assistant Examiner(s): TRINH, TAN H
• Application Number:
  US09/664,940
• Time in Patent Office: 1,498 Days
• Field of Search: 455/12.1, 455/13.1, 455/427-430, 455/431, 455/13.2, 244/158.R
• US Class Current: 455/427
• CPC Class Codes: H04B 7/19 Earth-synchronous stations
• CPC Class Codes: H04B 7/2041 Spot beam multiple access

Abstract

A satellite system includes a plurality of orbit slots having a first orbital and a second orbital slot. A first satellite occupies a first orbital slot and generates a first set of uniform beams. A second satellite located in a second orbital slot generates a second set of uniform beams. A tiling pattern on the face of the Earth has a plurality of cells, with each of the cells having a defined frequency for communication. The first set of beams and the second set of beams are generated according to parameters to avoid interference between them. The parameters may include satellite orbit separations, beam size, multiplicity of band reuse, and ground station received beamwidth.

Claims

1. A satellite system comprising:

a plurality of orbit slots having a first orbit slot and a second orbit slot;

a first satellite occupying a first orbit slot generating a first set of beams;

a second satellite occupying a second orbital slot generating a second set of beams; and

a tiling pattern for use on the surface of the Earth, said tiling pattern having a plurality of cells, each of said cells having a defined frequency for communication, said first set of beams and said second set of beams being generated according to predetermined parameters to avoid interference between said first set and said second set of beams,

wherein a first subset of beams of the plurality of beams sharing a same frequency band have a signal power at or above a minimum signal power and a C/(N+I) at or above a minimum C/(N+I) requirement, where C is an intended signal power, N is the noise power due to various natural thermal processes and I is a power due to all interfering signals occupying the same frequency band as the intended signal.

2. A satellite system as recited in claim 1 wherein said first satellite and said second satellite are aligned along a geostationary belt.

3. A satellite system as recited in claim 1 wherein said cells have an area that is proportional to latitude on the surface of the earth.

4. A satellite system as recited in claim 1 wherein said tiling pattern is continuous.

5. A satellite system as recited in claim 1 wherein said first set of beams and said second set of beams have a uniform size.

6. A satellite system as recited in claim 1 wherein said predetermined parameters include a tiling pattern having a reuse pattern.

7. A satellite system as recited in claim 1 wherein said first and second set of beams are congruant.

8. A satellite system as recited in claim 1 wherein said tiling pattern comprises a plurality of hexagons.

9. A satellite system as recited in claim 1 wherein said first orbital slot and said second orbital slot are coextensive.

10. A satellite system as recited in claim 1 wherein the first satellite and the second satellite form a fixed satellite service.

11. A satellite system as recited in claim 1 wherein the first satellite and the second satellite form a broadcast satellite service.

12. A satellite system as recited in claim 1 wherein the tiling pattern forms regularly distributed cell rings.

13. A method of operating a satellite system comprising the steps of:

defining a tiling pattern for use on the surface of the earth having a number of cells;

generating a first set of beams from a first satellite, each of the beams directed to a first group of the cells;

generating a second set of beams from a second satellite, each of the beams in said second set of beams directed to a second group of the cells, wherein a first subset of beams of the plurality of beams sharing a same frequency band have a signal power at or above a minimum signal power and a C/(N+I) at or above a minimum C/(N+I) requirement, where C is an intended signal power, N is the noise power due to various natural thermal processes and I is a power due to all interfering signals occupying the same frequency band as the intended signal; and

coordinating coverage from said first set of beams and said second set of beams to avoid interference between the first set of beams and the second set of beams.

14. A method as recited in claim 13 wherein said steps of generating a first set of beams from a first satellite and generating a second set of beams from a second satellite comprise the stop of generating beams having a size and alignment corresponding to said cell.

15. A method as recited in claim 13 wherein the step of defining a tiling pattern comprises the step of defining a plurality of hexagonal cells.

16. A method as recited in claim 13 wherein the step of generating a set of beams from a first satellite comprises the step of generating beams only over a landmass on the surface of the earth.

17. A method as recited in claim 13 wherein said first satellite and said second satellite occupy coextensive satellite slots.

18. A method as recited in claim 13 wherein the first satellite and the second satellite are geostationary.

19. A method as recited in claim 13 further comprising forming a fixed satellite service using the first satellite and the second satellite.

20. A method as recited in claim 13 further comprising forming a broadcast satellite service using the first satellite and the second satellite.

21. A system of geostationary satellite orbits coordinatable with a geostationary belt of satellite positions having a plurality of geostationary slots, said system comprising:

a plurality of satellites forming a coordinatable system of geostationary satellite orbits that provide satellite coverage continuously within a specified service area;

each satellite position being located in one of said plurality of geostationary slots and generating a plurality of beams; and

a tiling pattern for use on the surface of the earth, said tiling pattern having a plurality of cells corresponding to said plurality of beams, each of said cells having a defined frequency for communication and a frequency reuse spacing,

wherein a first subset beams of the plurality of beams sharing a same frequency band have a substantially uniform signal power and a uniform C/(N+I) requirement, where C is an intended signal power, N is the noise power due to various natural thermal processes and I is a power due to all interfering signals occupying the same frequency band as the intended signal.