System and method for frequency re-use in a sectorized cell pattern in a wireless communication system

• US 20040063433A1
• Filed: 10/14/2003
• Published: 04/01/2004
• Est. Priority Date: 12/08/2000
• Status: Active Grant

• Current Assignee: Harris Corporation (L3Harris Technologies, Inc.)
• Original Assignee: Harris Corporation (L3Harris Technologies, Inc.)
• Inventors: Garrison, G. Jack
• Granted Patent: US 7,231,214 B2
• Time in Patent Office: Days
• US Class Current: 455/447
• CPC Class Codes: H04W 16/00 Network planning, e.g. coverage or traffic planning tools; Network deployment, e.g. resource partitioning or cells structures
• CPC Class Codes: H04W 16/12 Fixed resource partitioning
• CPC Class Codes: H04W 16/24 Cell structures

Abstract

The present invention relates to a system and method for frequency re-use in a wireless communication system. More particularly, the inventive system and method provides for maximum coverage of a service area with a pattern of cells each having a sectorized hub antenna pattern where only a limited number of communication channels are available.

Claims

1. A repeatable pattern of frequency reuse in a wireless communication system comprising:

sixteen substantially circular cells of approximately the same radius arranged in a four-by-four grid such that no two cells substantially overlap and where each cell is substantially tangent with its adjacent rank and file neighbors, wherein each cell includes a hub with four antennas wherein each antenna services a separate one of four substantially non-overlapping ninety degree sectors and is capable of communicating on each of eight frequencies and on either of two polarizations per frequency, whereby for each hub one set of opposing ninety degree sectors communicate on a one of said eight frequencies at a one of said polarizations and the other set of opposing ninety degree sectors communicate on a different one of said eight frequencies at the other of said polarizations;

eight cell types wherein each cell type communicates over a unique combination of frequencies;

a first and a second group of four cells, each group comprising a two-by-two grid of cells such that,

said first group of four cells comprising four different cell types of said eight cell types, said cells arranged so that facing sectors of rank and file adjacent cells are of a different polarity, and

said second group of four cells comprising the remaining four different cell types, said cells arranged so that facing sectors of rank and file adjacent cells are of a different polarity;

a third and a fourth group of four cells, each group comprising a two-by-two grid of cells such that,

said third group of four cells comprising the same four cell types as said first group wherein the frequency and polarization assignments are interchanged between the pairs of opposing sectors for each cell, said four cells arranged identically to the cells in said first group, and

said fourth group of four cells comprising the same four cell types as said second group wherein the frequency and polarization assignments are interchanged between the pairs of opposing sectors for each cell, said four cells arranged identically to the cells in said second group;

wherein said four groups of cells are arranged in said four-by-four grid so that said first and third group of cells are not rank and file adjacent and so that facing cells between rank and file adjacent groups are of different frequencies.

2. The pattern of claim 1 wherein said polarizations are mutually orthogonal.

3. The pattern of claim 1 wherein the communication system is a time division duplex system.

4. The pattern of claim 3 wherein the communication system is an adaptive time division duplex system.

5. The pattern of claim 4 wherein said eight frequencies are in the millimeter frequency range.

6. The pattern of claim 5 wherein said eight frequencies are each in the range of 10-60 GHz.

7. The pattern of claim 1 wherein the cells are not synchronized.

8. The pattern of claim 7 wherein the sectors within the cells are not synchronized.

9. The pattern of claim 1 wherein said sixteen cells are generally circular, are of approximately the same radius, and are arranged in a four-by-four square grid such that the distance between the centers of any two horizontally and any two vertically adjacent cells is approximately twice a cell radius.

10. A horizontally and vertically repeatable pattern of cells in a multi-cell pattern of cells forming a rectilinear grid in a communication system wherein each cell is divided into four ninety degree sectors with at least one antenna per sector whereby each antenna is capable of operating in one of two polarization modes for each communication frequency, the improvement wherein each cell uses two frequencies and adjacent sectors of each cell alternate in frequency and polarization.

11. The pattern of claim 10 wherein said polarizations are mutually orthogonal.

12. The pattern of claim 11 wherein diagonally alternate cells with the grid are rotated ninety degrees relative to each other.

13. The pattern of claim 12 wherein the number of frequencies is eight.

14. The pattern of claim 13 wherein each cell is one of eight cell types whereby each cell type uses a unique combination of frequencies and polarizations.

15. The pattern of claim 14 wherein each cell type is repeated once within the pattern.

16. The pattern of claim 15 wherein the communication system is a time division duplex system.

17. The pattern of claim 16 wherein the communication system is an adaptive time division duplex system.

18. The pattern of claim 17 wherein said eight frequencies are in the millimeter frequency range.

19. The pattern of claim 18 wherein said eight frequencies are each in the range of 10-60 GHz.

20. In a horizontally and vertically repeatable pattern of cells in a multi-cell pattern of cells forming a rectilinear grid in a communication system wherein each cell is divided into four ninety degree sectors with at least one antenna per sector whereby each antenna is capable of operating in one of two polarization modes for each communication frequency, the method of reducing co-channel interference comprising the steps of:

(a) alternating adjacent sectors of each cell in frequency and polarization; and

(b) orienting at least one pair of alternate diagonal cells within the grid ninety degrees relative to each other.

21. The method of claim 20 wherein adjacent channel interference is reduced.

22. The pattern of claim 20 wherein said polarizations are mutually orthogonal.

23. The method of claim 22 wherein the number of frequencies is eight.

24. The method of claim 23 wherein each cell is one of eight cell types whereby each cell type uses a unique combination of frequencies and polarizations.

25. The method of claim 24 wherein each cell type is repeated once within the pattern.

26. The pattern of claim 22 wherein the communication system is a time division duplex system.

27. The pattern of claim 26 wherein the communication system is an adaptive time division duplex system.

28. The pattern of claim 27 wherein said eight frequencies are in the millimeter frequency range.

29. The pattern of claim 28 wherein said eight frequencies are each in the range of 10-60 GHz.

30. In a pattern of sixteen cells arranged in a four-by-four grid in a multi-cell pattern of cells forming a rectilinear grid in a communication system wherein each cell is divided into four ninety degree sectors with at least one antenna per sector whereby each antenna is capable of operating in one of two polarization modes for each of eight communication frequencies whereby for each hub one set of opposing ninety degree sectors communicate on a one of said eight frequencies at a one polarization and the other set of opposing ninety degree sectors communicate on a different one of said eight frequencies at the other polarization, the method of reducing co-channel interference comprising the steps of:

(a) dividing the sixteen cells into four groups of four cells whereby each group comprises a two-by-two grid of cells;

(b) providing eight cell types wherein each cell type communicates over a unique combination of frequencies;

(c) providing a first group of four cells comprising four different cell types of said eight cell types, said cells arranged so that facing sectors of rank and file adjacent cells are of a different polarity;

(d) providing a second group of four cells comprising the remaining four different cell types, said cells arranged so that facing sectors of rank and file adjacent cells are of a different polarity;

(e) repeating said first and second group of cells diagonally within said sixteen cell pattern;

(f) rotating the frequency and polarization assignments in the sectors of each cell of the repeated first and second group of cells by ninety degrees relative to the frequency and polarization assignments in the sectors of the first and second group of cells.

31. The method of claim 30 wherein adjacent channel interference is reduced.

32. The pattern of claim 30 wherein said polarizations are mutually orthogonal.

33. The pattern of claim 32 wherein the communication system is a time division/duplex system.

34. The pattern of claim 33 wherein the communication system is an adaptive time division duplex system.

35. The pattern of claim 34 wherein said eight frequencies are in the millimeter frequency range.

36. The pattern of claim 35 wherein said eight frequencies are each in the range of 10-60 GHz.

37. A pattern of frequency reuse in a wireless communication system including sixteen substantially circular cells of approximately the same radius arranged in a repeatable four-by-four grid forming a parallelogram so that the edge of any one cell is tangent to the edge of six other cells, wherein each cell includes a hub with four antennas wherein each antenna services a separate one of four substantially non-overlapping ninety degree sectors and is capable of communicating on each of eight frequencies and on either of two polarizations per frequency, whereby for each hub one set of opposing ninety degree sectors communicate on a one of said eight frequencies at a one polarization and the other set of opposing ninety degree sectors communicate on a different one of said eight frequencies at the other polarization, said pattern comprising:

eight cell types wherein each cell type communicates over a unique combination of frequencies;

a first group of four cells comprising four different cell types of said eight cell types, said cells arranged so that the centers of each cell are collinear and the edges of adjacent cells are tangent, whereby facing sectors of adjacent cells are of a different polarity;

a second group of four cells comprising the remaining four different cell types, said cells arranged so that the centers of each cell are collinear and the edges of adjacent cells are tangent, whereby facing sectors of adjacent cells are of a different polarity, and whereby said first and second groups of cells are arranged so that each cell of each group is adjacent to and tangent to at least one cell of the other group of cells;

a third group of four cells comprising the same four cell types as said first group wherein the frequency and polarization assignments are exchanged between the pairs of opposing sectors for each cell, said four cells arranged so that the centers of each cell are collinear and the edges of adjacent cells are tangent, and whereby said second and third groups of cells are arranged so that each cell of each group is adjacent to and tangent to at least one cell of the other group, and whereby no cell adjacent to a cell in the third group is also adjacent to a cell in the first group with a corresponding combination of frequencies as said cell in the third group;

a fourth group of four cells comprising the same four cell types as said second group wherein the frequency and polarization assignments are exchanged between the pairs of opposing sectors for each cell, said four cells arranged so that the centers of each cell are collinear and the edges of adjacent cells are tangent, and whereby said third and fourth groups of cells are arranged so that each cell of each group is adjacent to and tangent to at least one cell of the other group, and whereby no cell adjacent to a cell in the fourth group is also adjacent to a cell in the second group with a corresponding combination of frequencies as said cell in the fourth group.

38. The pattern of claim 37 wherein said sixteen cells are generally hexagonal in shape.

39. The pattern of claim 37 wherein said pattern is repeated horizontally and vertically.

40. The pattern of claim 37 wherein said polarizations are mutually orthogonal.

41. The pattern of claim 40 wherein the communication system is a time division duplex system.

42. The pattern of claim 41 wherein the communication system is an adaptive time division duplex system.

43. The pattern of claim 42 wherein said eight frequencies are in the millimeter frequency range.

44. The pattern of claim 43 wherein said eight frequencies are each in the range of 10-60 GHz.

45. The pattern of claim 44 wherein the cells are not synchronized.

46. The pattern of claim 45 wherein the sectors within the cells are not synchronized.

47. A pattern of frequency reuse in a wireless communication system including sixteen cells arranged in a four-by-four grid including four sub-clusters arranged in a two-by-two grid of four cells, wherein each cell includes a hub with four antennas in which each antenna services a separate one of four substantially non-overlapping ninety degree sectors and is capable of communicating on each of eight frequencies and on either of two polarizations per frequency, wherein for each hub each sector communicates on a different frequency in which two adjacent sectors communicate at a one polarization and the other two adjacent sectors communicate at the other polarization, said pattern comprising:

eight cell types wherein each cell type communicates over a unique combination of frequencies whereby the eight cell types are comprised of four frequencies at said one polarity and four frequencies at said other polarity;

a first sub-cluster comprising four different cell types of said eight cell types, said cells arranged so that facing sectors of adjacent cells communicate on a same frequency and a same polarization;

a second sub-cluster comprising the remaining four different cell types, said cells arranged so that facing sectors of adjacent cells communicate on a same frequency and a same polarization;

a third sub-cluster identical to said first sub-cluster;

a fourth sub-cluster identical to said second sub-cluster;

wherein said sub-clusters are arranged in said four-by-four grid so that said first and third sub-clusters are not adjacent and so that said facing cells between adjacent sub-clusters communicate on a same frequency and a same polarization.

48. The pattern of claim 47 wherein said polarizations are mutually orthogonal.

49. The pattern of claim 47 wherein the communication system is a time division duplex system.

50. The pattern of claim 49 wherein the communication system is an adaptive time division duplex system.

51. The pattern of claim 50 wherein said eight frequencies are in the millimeter frequency range.

52. The pattern of claim 51 wherein said eight frequencies are each in the range of 10-60 GHz.

53. The pattern of claim 52 wherein ones of said cells are synchronized.

54. The pattern of claim 53 wherein adjacent sectors communicating on a same frequency and a same polarization are synchronized.

55. The pattern of claim 54 wherein said adjacent sectors communicate with a common dynamic asymmetric synchronization.

56. The pattern of claim 47 including at least one additional sector communicating on a frequency and polarization combination of said eight frequencies and two polarizations that is not used in said pattern, whereby said additional sector is overlayed on at least one of the sectors in said pattern that has a similar polarization to the polarization of said additional sector.

57. The pattern of claim 56 wherein said additional sector is a ninety-degree sector.

58. The pattern of claim 56 wherein said additional sector is a forty-five degree sector.

59. A method of reducing co-channel interference in a horizontally and vertically repeatable pattern of cells in a multi-cell pattern of cells forming a rectilinear grid in a communication system wherein each cell includes a hub with four antennas wherein each antenna services a separate one of four substantially non-overlapping ninety degree sectors and is capable of communicating in one of two polarization modes for each communication frequency used by the communication system, whereby for each hub one set of opposing ninety degree sectors communicate on a one of said communication frequencies at a one of said polarizations and the other set of opposing ninety degree sectors communicate on a different one of said communication frequencies at the other of said polarizations, the method comprising the steps of:

(a) providing eight cell types wherein each cell type comprises a unique combination of said two sets of frequency and polarization;

(b) providing two sub-clusters of cells each of four cells arranged in a two-by-two grid wherein a first sub-cluster comprises four cells each of a different cell type of said eight cell types and wherein a second sub-cluster comprises four cells each of a different cell type of the remaining four cell types;

(c) alternating said two sub-clusters horizontally and vertically within the multi-cell pattern of cells; and

(d) orienting each pair of alternate diagonal cells within the multi-cell pattern of cells ninety degrees relative to each other.

60. The method of claim 59 wherein adjacent channel interference is reduced.

61. The pattern of claim 59 wherein said polarizations are mutually orthogonal.

62. The method of claim 61 wherein the number of frequencies is eight.

63. The method of claim 61 wherein the number of frequencies is at least eight.

64. The method of claim 63 wherein each cell type is repeated once within the pattern.

65. The pattern of claim 61 wherein the communication system is a time division duplex system.

66. The pattern of claim 65 wherein the communication system is an adaptive time division duplex system.

67. The pattern of claim 66 wherein said eight frequencies are in the millimeter frequency range.

68. The pattern of claim 67 wherein said eight frequencies are each in the range of 10-60 GHz.