Apparatus, method, and computer program products for cell-hopping satellite communications

• US 6,522,643 B1
• Filed: 07/21/1999
• Issued: 02/18/2003
• Est. Priority Date: 07/21/1999
• Status: Expired due to Term

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Original Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Inventors: Dentinger, Aaron M., Maalouf, Khalil J., Jacomb-Hood, Anthony W.
• Primary Examiner(s): Trost, William
• Assistant Examiner(s): Le, Danh C
• Application Number:
  US09/358,385
• Time in Patent Office: 1,308 Days
• Field of Search: 375/132, 375/133, 375/267, 375/347, 342/457, 455/12.1, 455/13.1, 455/63, 455/427, 455/429, 455/450, 455/452, 370/319, 370/321, 370/322, 370/329, 370/330-333, 370/336, 370/337, 370/341, 370/343
• US Class Current: 370/347
• CPC Class Codes: H04B 7/18539 Arrangements for managing radio, resources, i.e. for establishing or releasing a connection
• CPC Class Codes: H04W 16/14 Spectrum sharing arrangements between different networks
• CPC Class Codes: H04W 72/02 Selection of wireless resources by user or terminal
• CPC Class Codes: H04W 72/541 using the level of interference
• CPC Class Codes: H04W 84/042 Public Land Mobile systems, e.g. cellular systems
• CPC Class Codes: H04W 84/06 Airborne or Satellite Networks space-based or airborne stations H04B7/185

Abstract

An apparatus, method, and computer program product for assigning communication resources in a beam-hopping cellular communication system. The satellite has a multiple beam antenna that covers a number of cells that is greater than the number of available beams In a preferred embodiment, the method includes the steps of selecting a frequency for each beam, computing a dwell time for each cell based on the traffic estimates for each cell and the number of available beams, and selecting a cell hopping sequence for each beam based on the dwell times and predicted inter-beam interference.

Claims

1. An apparatus for assigning communication resources in a beam-hopping cellular communication system having a multiple beam antenna covering a number of cells that is greater than the number of available beams, the apparatus comprising:

means for selecting a frequency for each beam; and

means for computing a dwell time for each cell based on the traffic estimates for each cell and the number of available beams; and

means for selecting a cell hopping sequence for each beam based on the dwell times and predicted inter-beam interference.

2. The apparatus of claim 1, wherein said means for computing comprises:

means for computing a dwell time percentage for each cell as the ratio of the traffic estimate for the cell to the total traffic estimate for all cells.

3. The apparatus of claim 2, wherein said means for computing further comprises:

means for defining a coverage template, the coverage template having a row for each beam and a column for each of a predetermined number of uniform time slots; and

means for allocating a number of the time slots to each cell, the number based on the dwell time percentage for the cell.

4. The apparatus of claim 3, wherein said means for selecting comprises:

means for selecting the cell that is not assigned to a beam and is allocated the greatest number of time slots;

means for selecting the beam having the greatest number of unassigned time slots; and

means for assigning the selected cell to the selected beam.

5. The apparatus of claim 4, wherein said means for assigning comprises:

means for predicting the inter-beam interference that would result from the assignment; and

means for assigning the cell to the beam having the next greatest number of unassigned time slots when the predicted inter-beam interference exceeds a predetermined threshold.

6. The apparatus of claim 5, wherein said means for assigning further comprises:

means for reducing the time slot allocation of each cell and initializing the coverage template when a cell cannot be assigned to a beam.

7. The apparatus of claim 6, wherein said means for reducing comprises:

means for reducing the time slot allocation for each cell according to its dwell time percentage.

8. The apparatus of claim 5, wherein said means for assigning further comprises:

means for increasing the time slot allocation,of each cell when unassigned time slots remain in the coverage template for the beam after all cells have been assigned.

9. The apparatus of claim 8, wherein said means for increasing comprises:

means for increasing the time slot allocation for each cell according to its dwell time percentage when the predicted inter-beam interference is below a further predetermined threshold.

10. The apparatus of claim 5, wherein said means for predicting comprises:

means for predicting the inter-beam interference based on the antenna pattern of the multiple beam antenna.

11. The apparatus of claim 1, further comprising:

means for updating the traffic estimates;

means for modifying the dwell time for each cell based on the updated traffic estimates for each cell and the number of available time slots; and

means for modifying the cell hopping sequence for each beam based on the modified dwell times.

12. A method for assigning communication resources in a beam-hopping cellular communication system having a multiple beam antenna covering a number of cells that is greater than the number of available beams, the method comprising:

a) selecting a frequency for each beam;

b) computing a dwell time for each cell based on the traffic estimates for each cell and the number of available beams; and

c) selecting a cell hopping sequence for each beam based on the dwell times and predicted inter-beam interference.

13. The method of claim 12, wherein step b) comprises:

computing a dwell time percentage for each cell as the ratio of the traffic estimate for the cell to the total traffic estimate for all cells.

14. The method of claim 13, wherein step b) further comprises:

b1) defining a coverage template, the coverage template having a row for each beam and a column for each of a predetermined number of uniform time slots; and

b2) allocating a number of the time slots to each cell, the number based on the dwell time percentage for the cell.

15. The method of claim 14, wherein step c) comprises:

c1) selecting the cell that is not assigned to a beam and is allocated the greatest number of time slots;

c2) selecting the beam having the greatest number of unassigned time slots;

c3) assigning the selected cell to the selected beam; and

c4) repeating step c1), c2) and c3) until all of the cells are assigned to beams.

16. The method of claim 15, wherein step c3) comprises:

predicting the inter-beam interference that would result from the assignment; and

assigning the cell to the beam having the next greatest number of unassigned time slots when the predicted inter-beam interference exceeds a predetermined threshold.

17. The method of claim 16, wherein step c3) further comprises:

reducing the time slot allocation of each cell, initializing the coverage template, and repeating steps c1), c2), c3) and c4) when a cell cannot be assigned to a beam.

18. The method of claim 17, wherein the reducing step comprises:

reducing the time slot allocation for each cell according to its dwell time percentage.

19. The method of claim 16, wherein step c3) further comprises:

increasing the time slot allocation of each cell and repeating steps c1), c2), c3) and c4) when unassigned time slots remain in the coverage template for the beam after all cells have been assigned.

20. The method of claim 19, wherein the increasing step comprises:

increasing the time slot allocation for each cell according to its dwell time percentage when the predicted inter-beam interference is below a further predetermined threshold.

21. The method of claim 16, wherein the predicting step comprises:

predicting the inter-beam interference based on the antenna pattern of the multiple beam antenna.

22. The method of claim 12, further comprising:

d) updating the traffic estimates;

e) modifying the dwell time for each cell based on the updated traffic estimates for each cell and the number of available time slots; and

f) modifying the cell hopping sequence for each beam based on the modified dwell times.

23. A computer program product for assigning communication resources in a beam-hopping cellular communication system having a multiple beam antenna covering a number of cells that is greater than the number of available beams, said computer program product comprising a computer usable medium having computer readable program code means embodied in said medium, said computer readable program code means comprising:

a first computer readable program code means for causing a computer to select a frequency for each beam;

a second computer readable program code means for causing a computer to compute a dwell time for each cell based on the traffic estimates for each cell and the number of available beams; and

a third computer readable program code means for causing a computer to select a cell hopping sequence for each beam based on the dwell times and predicted inter-beam interference.

24. The computer program product of claim 23, wherein said second computer readable program code means comprises:

computer readable program code means for causing a computer to compute a dwell time percentage for each cell as the ratio of the traffic estimate for the cell to the total traffic estimate for all cells.

25. The computer program product of claim 24, wherein said second computer readable program code means further comprises:

computer readable program code means for causing a computer to define a coverage template, the coverage template having a row for each beam and a column for each of a predetermined number of uniform time slots; and

computer readable program code means for causing a computer to allocate a number of the time slots to each cell, the number based on the dwell time percentage for the cell.

26. The computer program product of claim 25, wherein said third computer readable program code means further comprises:

computer readable program code means for causing a computer to select the cell that is not assigned to a beam and is allocated the greatest number of time slots;

computer readable program code means for causing a computer to select the beam having the greatest number of unassigned time slots; and

computer readable program code means for causing a computer to assign the selected cell to the selected beam.

27. The computer program product of claim 26, wherein said computer readable program code means for causing a computer to assign comprises:

computer readable program code means for causing a computer to predict the inter-beam interference that would result from the assignment; and

computer readable program code means for causing a computer to assign the cell to the beam having the next greatest number of unassigned time slots when the predicted inter-beam interference exceeds a predetermined threshold.

28. The computer program product of claim 27, wherein said computer readable program code means for causing a computer to assign the selected cell to the selected beam further comprises:

computer readable program code means for causing a computer to reduce the time slot allocation of each cell and initializing the coverage template when a cell cannot be assigned to a beam.

29. The computer program product of claim 28, wherein said computer readable program code means for causing a computer to reduce further comprises:

computer readable program code means for causing a computer to reduce the time slot allocation for each cell according to its dwell time percentage.

30. The computer program product of claim 27, wherein said computer readable program code means for causing a computer to assign the selected cell to the selected beam further comprises:

computer readable program code means for causing a computer to increase the time slot allocation of each cell when unassigned time slots remain in the coverage template for the beam after all cells have been assigned.

31. The computer program product of claim 30, wherein said computer readable program code means for causing a computer to increase comprises:

computer readable program code means for causing a computer to increase the time slot allocation for each cell according to its dwell time percentage when the predicted inter-beam interference is below a further predetermined threshold.

32. The computer program product of claim 27, wherein said computer readable program code means for causing a computer to predict comprises:

computer readable program code means for causing a computer to predict the inter-beam interference based on the antenna pattern of the multiple beam antenna.

33. The computer program product of claim 23, wherein said computer readable program code means further comprises:

computer readable program code means for causing a computer to update the traffic estimates;

computer readable program code means for causing a computer to modify the dwell time for each cell based on the updated traffic estimates for each cell and the number of available time slots; and

computer readable program code means for causing a computer to modify the cell hopping sequence for each beam based on the modified dwell times.