Satellite system cell management

• US 5,227,802 A
• Filed: 12/23/1991
• Issued: 07/13/1993
• Est. Priority Date: 12/23/1991
• Status: Expired due to Term

• Current Assignee: CDC Propriete Intellectuelle
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Pullman, Michele A., Peterson, Kenneth M.
• Primary Examiner(s): Issing, Gregory C.
• Application Number:
  US07/812,389
• Time in Patent Office: 568 Days
• Field of Search: 342/350, 342/352, 342/353, 342/354, 342/360
• US Class Current: 342/352
• CPC Class Codes: H04B 7/2041 Spot beam multiple access

Abstract

There is provided a method and means for controlling the amount of overlap and gaps in coverage of antenna pattern cells of a moving satellite communication system, by determining the relative spatial location of overlapping or gaping cells of converging or diverging satellites as a function of time; determining a point where antenna coverage of one or more cells from a first moving satellite will overlap or gap one or more cells from a second satellite; and turning off or on one or more of the overlapping or gaping cells so as to eliminate interference therebetween without leaving substantial coverage gaps between adjacent antenna patterns.

Claims

1. A method of operation of a satellite communication system, comprising:

enabling first and second communication satellites having, respectively, first and second multicelled antenna patterns which move over the surface of the earth relative to each other and overlap by varying amounts as the orbital paths of the satellites converge and diverge, wherein the first and second satellites are active a majority of their orbits and simultaneously service substantially different, but adjacent geographical areas;

determining, respectively, the relative locations of first and second multicelled antenna coverage patterns of antennas of the first and second satellites;

determining positions in the orbits of the first and second satellites when the first and second multicelled antenna coverage patterns overlap by varying amounts as the satellites move with respect to each other; and

modifying the antenna coverage pattern of one or both satellites as a function of orbital position to avoid substantially interfering overlap or significant no-coverage gap.

2. The method of claim 1 wherein the first determining step comprises computing locations of centers of at least peripheral cells of the multicelled antenna patterns.

5. The method of claim 1 where the multicelled antenna coverage patterns are modified by incrementally changing the number or size or location of the cells.

3. A method of operation of a satellite communication system involving two or more satellites whose antenna patterns overlap or gap during some portion of an orbit of at least one of the satellites, comprising:

determining, respectively, first and second antenna coverage patterns of antennas of first and second satellites;

determining when the first and second antenna coverage patterns overlap or gap as one of the first or second satellites moves with resect to the other; and

modifying the antenna coverage pattern of one or both satellites as a function of time to avoid substantially interfering overlap or significant no-coverage gap, wherein the antenna converge patterns comprises cells whose activity is adapted to be modified, wherein the first determining step comprises computing locations of centers of at least peripheral cells of the antenna patterns, and

wherein the first determining step further comprises calculating center-to-center distances of approaching or receding cells of the first and second antenna coverage patterns.

4. A method of operation of a satellite communication system involving two or more satellites whose antenna patterns overlap or gap during some portion of an orbit of at least one of the satellites, comprising:

determining, respectively, first and second antenna coverage patterns of antennas of first and second satellites;

determining when the first and second antenna coverage patterns overlap or gap as one of the first or second satellites moves with respect to the other; and

modifying the antenna coverage pattern of one or both satellites as a function of time to avoid substantially interfering overlap or significant nocoverage gap, wherein the antenna coverage patterns comprise cells whose activity is adapted to be modified, wherein the first determining step comprises computing locations of centers of at least peripheral cells of the antenna patterns;

wherein the first determining step further comprises calculating center-to-center distances of approaching or receding cells of the first and second antenna coverage patterns; and

wherein the calculated center-to-center distances are compared to predetermined center-to-center distances for the same cells and the antenna coverage pattern of one or both satellites modified when the calculated center-to-center distances different from the predetermined center-to-center distance so as to result in substantial interference or non-coverage gap as the satellites approach or depart.

6. A method for controlling the operation of multi-satellite communication system, comprising:

determining information concerning the orbital position or time when an antenna pattern of a first orbiting satellite substantially overlaps or gaps an antenna pattern of a second satellite in a different but approaching orbit wherein both antenna patterns move over the surface of the earth and relative to each other and service, except for overlap, different geographic regions;

storing information related thereto on board the first or second satellite or both; and

based on such stored information, incrementally modifying the antenna pattern of one or both satellites to reduce the overlap or gap during portions of the orbit when the satellites converge or diverge.

7. The method of claim 6 wherein the modifying step further comprises modifying the antenna pattern of one or both satellites to substantially maintain contact between the antenna patterns as the satellites diverge by alternately, between satellites, turning at least one of the antenna cells on or off as needed.

8. The method of claim 6 wherein the first determining step comprises determining a cyclical orbital time when the antenna pattern of the first satellite substantially overlaps the antenna pattern of the second satellite and the modifying step comprises modifying the antenna pattern of one or both satellites whenever such orbital times repeat.

9. The method of claim 8 wherein the storing step comprises storing the predetermined orbital times when overlap is significant enough to cause signal interference between unmodified antenna patterns of converging satellites so as to warrant modification of an antenna pattern and the modifying step comprises modifying the antenna pattern when actual orbital time substantially equals the predetermined orbital times.

10. The method of claim 9 further comprising periodically updating the predetermined orbital times at which antenna pattern modification is desired to avoid substantial interference.

11. The method of claim 6 wherein the antenna pattern being modified comprises cells and modification of the antenna pattern comprises turning interfering cells off and gaping cells on.

12. The method of claim 6 wherein the first determining step comprises determining a cyclical orbital position when the antenna pattern of the first satellite substantially overlaps the antenna pattern of the second satellite and the modifying step comprises modifying the antenna pattern of one or both satellites whenever such orbital positions repeat.

13. The method of claim 12 wherein the storing step comprises storing the predetermined orbital positional information concerning when overlap is significant enough to cause signal interference between unmodified antenna patterns of converging satellites so as to warrant modification of an antenna pattern and the modifying step comprises modifying the antenna pattern when actual orbital position information substantially equals the predetermined orbital positional information indicating substantial signal interference.

14. The method of claim 13 further comprising periodically updating the the predetermined orbital positional information at which antenna pattern modification is desired to avoid substantial interference.

15. The method of claim 13 wherein the antenna pattern being modified comprises cells and the predetermined stored orbital positional information comprises minimum intercellular distances of overlapping or gaping cells.

16. The method of claim 15 wherein modification of the antenna pattern comprises turning interfering cells off when the actual intercellular distances are less than the stored minimum predetermined intercellular distances.

17. The method of claim 6 further comprising modifying the antenna pattern of whichever satellite has a larger angle to a nadir of a ground based user of the system.

18. A system for managing satellite antenna coverage of a non-geostationary orbiting multi-satellite system for providing communication services to users on earth to avoid interference or gaps between antenna patterns of approaching or departing satellites, comprising:

memory means for storing information concerning predetermined portions of an orbit when an antenna pattern of one active satellite will or will not interfere which an antenna pattern of another active satellite, wherein said antenna patterns of said active satellites move over the surface of the earth as a consequence of the orbits;

satellite locator means for determining current orbital information of the one satellite; and

controller means for comparing such current orbital information to the stored orbital information to determine when a predetermined decision criteria is met, and then incrementally modifying an antenna pattern associated with the one or another satellite to avoid substantial interference or gaps between their antenna patterns while both satellites continue providing communication services.

19. The system of claim 18 wherein the system further comprises a communication routing matrix for altering routing of transmitted or received signals to or from individually controllable cells of an antenna.

20. The system of claim 18 wherein the memory means, locator means and controller means are on board the one or the another satellite.

21. The system of claim 18 wherein the antenna pattern contains cells and wherein the controller means for modifying an antenna pattern further comprises means for turning off or on individual antenna cells.

22. The system of claim 18 wherein the antenna pattern contain cells and wherein the controller means for modifying an antenna pattern further comprises means for varying the shape or size of individual antenna cells.

23. A method of operation of a non-geostationary orbiting satellite communication system involving two or more satellites whose antenna patterns overlap or gap during some portion of an orbit of at least one of the satellites, comprising:

determining, respectively, first and second multicelled antenna coverage patterns of antennas of first and second satellites;

determining when the first and second multicelled antenna coverage patterns overlap or gap as one of the first or second satellites moves with respect to the other; and

incrementally modifying the antenna coverage pattern of one or both satellites as a function of time by altering one or more of the multiple cells of one or both of the antenna patterns to avoid substantially interfering overlap or significant no-coverage gap while both satellites continue to provide communication services.

24. A method of operation of a non-geostationary orbiting satellite communication system involving two or more satellites whose antenna patterns overlap or gap during some portion of an orbit of at least one of the satellites, comprising:

determining, respectively, first and second antenna coverage patterns of antennas of first and second satellites;

determining when the first and second antenna coverage patterns overlap or gap as one of the first or second satellites moves with respect to the other; and

incrementally modifying the antenna coverage pattern of one or both satellites as a function of time to avoid substantially interfering overlap or significant no-coverage gap while maintaining operation of both satellites.

25. A method of operation of a non-geostationary orbiting satellite communication system involving two or more satellites whose antenna patterns overlap or gap during some portion of an orbit of at least one of the satellites, comprising:

determining, respectively, first and second multicelled antenna coverage patterns of antennas of first and second satellites;

determining when the first and second multicelled antenna coverage patterns overlap or gap as one of the first or second satellites moves with respect to the other; and

incrementally modifying peripheral cells of the multicelled antenna coverage pattern of one or both satellites as a function of time to avoid substantially interfering overlap or significant no-coverage gap while both satellites continue providing communication to users on earth.