Methods and determining an optimum sector distribution within a coverage area of a wireless communication system

• US 6,418,327 B1
• Filed: 04/06/1999
• Issued: 07/09/2002
• Est. Priority Date: 04/06/1999
• Status: Expired due to Fees

• Current Assignee: Axxcelera Broadband Wireless, Inc. (Moseley Wireless Solutions Group)
• Original Assignee: Spike Broadband Systems, Inc. (REMEC, Inc.)
• Inventors: Dziadek, Edward, Carey, Douglas, Ryan, Donna, Herscovici, Naftali, Peragine, Thomas
• Primary Examiner(s): MAUNG, NAY AUNG
• Application Number:
  US09/287,142
• Time in Patent Office: 1,190 Days
• Field of Search: 455/422, 455/432, 455/436, 455/446, 455/453, 455/513, 455/560, 455/561, 455/562, 455/522, 455/277.1, 455/277.2, 455/278.1, 370/320, 370/252, 370/335, 370/339, 370/342
• US Class Current: 455/562.1
• CPC Class Codes: H04W 16/06 Hybrid resource partitioning, e.g. channel borrowing
• CPC Class Codes: H04W 16/24 Cell structures

Abstract

Methods for determining an optimum sector distribution within a coverage area of a wireless communication system are disclosed. A coverage area is divided into a number of sectors, each sector having a respective sector width. The wireless communication system emits a respective radiation pattern designated for each sector. The methods of the invention evaluate the interference in a given sector due to both neighboring radiation pattern main lobes and sidelobes from all other sectors within the coverage area using the same frequency channels. According to the methods of the invention, a sector width and/or radiation pattern may be determined which minimizes the interference, or undesired signal level, while maintaining a sufficiently uniform distribution of the desired signal level in each sector. The various embodiments of methods according to the invention may be implemented using software, for example, in the form of a simulation program.

Claims

1. A method for determining an optimum sector distribution within a coverage area of a wireless communication system, the coverage area being divided into a plurality of sectors, each sector having a respective sector width, the wireless communication system emitting a respective radiation pattern designated for each sector, the method comprising steps of:

a) selecting the radiation pattern designated for each sector;

b) selecting the sector width of each sector based on the radiation pattern;

c) calculating a desired signal level in a first sector of the plurality of sectors based on the radiation pattern designated for the first sector;

d) calculating a sum of undesired interference levels in the first sector based on the radiation patterns designated for at least some other sectors of the plurality of sectors except the first sector;

e) calculating a ratio of the desired signal level to the sum of the undesired interference levels for the first sector;

f) modifying the sector width of at least the first sector; and

g) repeating steps c), d), e), and f) until the ratio for the first sector is maximized.

2. The method of claim 1, further including a step of:

h) repeating steps c), d), e), f) and g) for each sector of the coverage area, substituting consecutive other sectors of the plurality of sectors for the first sector.

3. The method of claim 1, wherein:

the radiation pattern designated for each sector represents a frequency channel having a carrier frequency; and

the step of calculating the sum of the undesired interference levels includes a step of calculating a sum of undesired interference levels in the first sector due to the frequency channels designated for all other sectors of the plurality of sectors having a same carrier frequency as the first sector.

4. The method of claim 3, wherein the frequency channels designated for alternate sectors have the same carrier frequency.

5. The method of claim 1, wherein the step of selecting the radiation pattern designated for each sector includes a step of selecting a spatial profile of the radiation pattern designated for each sector such that at least two radiation patterns have different spatial profiles.

6. The method of claim 1, wherein the step of selecting the radiation pattern designated for each sector includes a step of selecting a power level of the radiation pattern designated for each sector such that at least two radiation patterns have different power levels.

7. The method of claim 1, wherein the step of selecting the radiation pattern designated for each sector includes a step of selecting an essentially identical power level of the radiation pattern designated for each sector.

8. The method of claim 7, wherein the step of selecting the radiation pattern designated for each sector includes a step of selecting an essentially identical spatial profile of the radiation pattern designated for each sector.

9. The method of claim 8, wherein the step of selecting the sector width of each sector includes a step of selecting an essentially identical sector width of each sector.

10. The method of claim 9, wherein the step of modifying the sector width of at least the first sector includes a step of modifying each sector width by a same amount.

11. The method of claim 1, wherein the coverage area spans a 360 degree azimuth.

12. The method of claim 11, wherein:

the radiation pattern designated for each sector represents a frequency channel having a carrier frequency; and

the step of selecting the sector width of each sector includes a step of selecting the sector width of each sector such that the coverage area is divided into a first number of sectors that is divisible by a second number of unique frequency channels.

13. The method of claim 12, wherein the step of modifying the sector width of at least the first sector includes a step of modifying the sector width of each sector such that the coverage area is divided into a third number of sectors different from the first number and divisible by the second number of unique frequency channels.

14. The method of claim 1 1, wherein the step of selecting the sector width of each sector includes a step of selecting the sector width of each sector such that the coverage area is divided into a first even number of sectors.

15. The method of claim 14, wherein the step of modifying the sector width of at least the first sector includes a step of modifying the sector width of each sector such that the coverage area is divided into a second even number of sectors different from the first even number.

16. The method of claim 14, wherein the step of selecting the sector width of each sector includes a step of selecting an essentially identical sector width of each sector.

17. The method of claim 16, wherein the step of modifying the sector width of at least the first sector includes a step of modifying the sector width of each sector by a same amount such that the coverage area is divided into a second even number of sectors different from the first even number.

18. The method of claim 16, wherein the step of selecting the radiation pattern designated for each sector includes a step of selecting an essentially identical spatial profile of the radiation pattern designated for each sector such that the ratio is maximized when the sector width is approximately 16.4 degrees.

19. The method of claim 1, wherein:

the radiation pattern has a main lobe; and

the step of selecting the sector width of each sector includes a step of selecting twice a width of the main lobe at −

10 dB points of the main lobe as the sector width.

20. The method of claim 19, wherein after the step of calculating a ratio, the method further includes steps of:

e1) storing the calculated ratio for the first sector; and

e2) storing the sector width of the first sector.

21. The method of claim 20, wherein the step of modifying the sector width of at least the first sector includes a step of decreasing the sector width of at least the first sector.

22. The method of claim 20, wherein:

the coverage area spans a 360 degree azimuth; and

the step of modifying the sector width of at least the first sector includes a step of decreasing the sector width of each sector such that a number of sectors into which the coverage area is divided is increased by an integer value.

23. The method of claim 22, wherein the step of decreasing the sector width of each sector includes a step of decreasing the sector width of each sector such that the number of sectors into which the coverage area is divided is increased by an even integer value.

24. The method of claim 22, wherein the step of repeating includes steps of:

g1) repeating steps c), d), e), e1), e2) and f) until the sector width is less than a width of the main lobe at −

0.5 dB points of the main lobe; and

g2) selecting the stored sector width corresponding to a maximum stored ratio.

25. The method of claim 22, wherein the step of repeating includes steps of:

g1) repeating steps c), d), e), e1), e2) and f) until an incremental change in the ratio is below a predetermined threshold value; and

g2) selecting the stored sector width corresponding to a maximum stored ratio.

26. The method of claim 1, wherein the step of calculating the desired signal level in the first sector includes a step of calculating a minimum desired signal level in the first sector due to the radiation pattern designated for the first sector.

27. The method of claim 26, wherein:

the radiation pattern designated for each sector represents a frequency channel having a carrier frequency; and

the step of calculating the sum of the undesired interference levels includes a step of calculating a sum of average undesired interference levels in the first sector due to the frequency channels designated for all other sectors having a same carrier frequency as the first sector.

28. The method of claim 27, wherein the step of calculating the ratio for the first sector includes a step of calculating a ratio of the minimum desired signal level to the sum of the average undesired interference levels in the first sector.

29. The method of claim 26, wherein:

the radiation pattern designated for each sector represents a frequency channel having a carrier frequency; and

the step of calculating the sum of the undesired interference levels includes a step of calculating a sum of maximum undesired interference levels in the first sector due to the frequency channels designated for all other sectors having a same carrier frequency as the first sector.

30. The method of claim 29, wherein the step of calculating the ratio for the first sector includes a step of calculating a ratio of the minimum desired signal level to the sum of the maximum undesired interference levels in the first sector.

31. The method of claim 1, wherein the radiation pattern has a main lobe and a plurality of sidelobes, the plurality of sidelobes being distributed throughout the coverage area.

32. The method of claim 31, wherein the step of calculating the desired signal level in the first sector includes a step of determining a plot of desired signal levels in the first sector due to the radiation pattern designated for the first sector as a function of a plurality of angles within the first sector.

33. The method of claim 32, wherein:

the radiation pattern designated for each sector represents a frequency channel having a carrier frequency; and

the step of calculating a sum of undesired interference levels includes a step of determining a plot of a sum of undesired interference levels in the first sector, the undesired interference levels being due to the frequency channels designated for all other sectors having a same carrier frequency as the first sector, the plot of the sum being determined as a function of the plurality of angles within the first sector.

34. The method of claim 33, wherein the step of calculating the ratio for the first sector includes a step of determining a plot of ratios of the desired signal level and the sum of the undesired interference levels in the first sector as a function of the plurality of angles within the first sector.

35. The method of claim 34, wherein after the step of determining the plot of the ratios, the method further includes steps of:

e1) storing the plot of the ratios for the first sector; and

e2) storing the sector width of the first sector.

36. The method of claim 35, wherein the step of selecting the sector width of each sector includes a step of selecting approximately twice a width of the main lobe at −

10 dB points of the main lobe as the sector width.

37. The method of claim 36, wherein the step of modifying the sector width of at least the first sector includes a step of decreasing the sector width of at least the first sector by a predetermined amount.

38. The method of claim 37, wherein the step of repeating includes steps of:

g1) repeating steps c), d), e), e1), e2) and f) until the sector width of the first sector is less than a width of the main lobe at −

0.5 dB points of the main lobe; and

g2) selecting the stored sector width corresponding to the stored plot of the ratios having a highest value of a minimum ratio.

39. A method for determining an optimum sector distribution within a coverage area of a wireless communication system, the coverage area being divided into a plurality of sectors, each sector having a respective sector width, the wireless communication system emitting a respective radiation pattern designated for each sector, the method comprising steps of:

a) selecting the sector width of each sector;

b) selecting the radiation pattern designated for each sector based on the sector width;

c) calculating a desired signal level in a first sector of the plurality of sectors based on the radiation pattern designated for the first sector;

d) calculating a sum of undesired interference levels in the first sector based on the radiation patterns designated for at least some other sectors of the plurality of sectors except the first sector;

e) calculating a ratio of the desired signal level to the sum of the undesired interference levels for the first sector;

f) modifying the radiation pattern designated for at least one sector; and

g) repeating steps c), d), e), and f), substituting the modified radiation pattern designated for the at least one sector for the radiation pattern designated for the at least one sector, until the ratio is maximized.

40. The method of claim 39, wherein:

the radiation pattern designated for each sector represents a frequency channel having a carrier frequency; and

the step of calculating the sum of the undesired interference levels includes a step of calculating a sum of undesired interference levels in the first sector due to the frequency channels designated for all other sectors of the plurality of sectors having a same carrier frequency as the first sector.

41. The method of claim 40, wherein the radiation patterns designated for alternate sectors have the same carrier frequency.

42. The method of claim 39, wherein the step of selecting the radiation pattern designated for each sector includes a step of selecting a spatial profile of the radiation pattern designated for each sector such that at least two radiation patterns have different spatial profiles.

43. The method of claim 39, wherein the step of selecting the radiation pattern designated for each sector includes a step of selecting a power level of the radiation pattern designated for each sector such that at least two radiation patterns have different power levels.

44. The method of claim 39, wherein the step of selecting the radiation pattern designated for each sector includes a step of selecting an essentially identical power level of the radiation pattern designated for each sector.

45. The method of claim 44, wherein the step of selecting the radiation pattern designated for each sector includes a step of selecting an essentially identical spatial profile of the radiation pattern designated for each sector.

46. The method of claim 45, wherein the step of selecting the sector width of each sector includes a step of selecting an essentially identical sector width of each sector.

47. The method of claim 46, wherein the step of modifying the radiation pattern of at least one sector includes a step of identically modifying the radiation pattern of each sector.

48. The method of claim 39, wherein the coverage area spans a 360 degree azimuth.

49. The method of claim 48, wherein:

the radiation pattern designated for each sector represents a frequency channel having a carrier frequency; and

the step of selecting the sector width of each sector includes a step of selecting the sector width of each sector such that the coverage area is divided into a first number of sectors that is divisible by a second number of unique frequency channels.

50. The method of claim 49, wherein the step of modifying the sector width of at least the first sector includes a step of modifying the sector width of each sector such that the coverage area is divided into a third number of sectors different from the first number and divisible by the second number of unique frequency channels.

51. The method of claim 48, wherein the step of selecting the sector width of each sector includes a step of selecting the sector width of each sector such that the coverage area is divided into an even number of sectors.

52. The method of claim 51, wherein the step of selecting the sector width of each sector includes a step of selecting an essentially identical sector width of each sector.

53. The method of claim 39, wherein the step of calculating the desired signal level in the first sector includes a step of calculating a minimum desired signal level in the first sector due to the radiation pattern designated for the first sector.

54. The method of claim 53, wherein:

the radiation pattern designated for each sector represents a frequency channel having a carrier frequency; and

the step of calculating the sum of the undesired interference levels includes a step of calculating a sum of average undesired interference levels in the first sector due to the frequency channels designated for all other sectors having a same carrier frequency as the first sector.

55. The method of claim 54, wherein the step of calculating the ratio for the first sector includes a step of calculating a ratio of the minimum desired signal level to the sum of the average undesired interference levels in the first sector.

56. The method of claim 53, wherein:

the radiation pattern designated for each sector represents a frequency channel having a carrier frequency; and

the step of calculating the sum of the undesired interference levels includes a step of calculating a sum of maximum undesired interference levels in the first sector due to the frequency channels designated for all other sectors using a same carrier frequency as the first sector.

57. The method of claim 56, wherein the step of calculating the ratio includes a step of calculating a ratio of the minimum desired signal level to the sum of the maximum undesired interference levels in the first sector.

58. The method of claim 39, wherein the radiation pattern has a main lobe and a plurality of sidelobes, the plurality of sidelobes being distributed throughout the coverage area.

59. The method of claim 58, wherein the step of calculating the desired signal level in the first sector includes a step of determining a plot of desired signal levels in the first sector due to the radiation pattern designated for the first sector as a function of a plurality of angles within the first sector.

60. The method of claim 59, wherein:

the radiation pattern designated for each sector represents a frequency channel having a carrier frequency; and

the step of calculating a sum of undesired interference levels includes a step of determining a plot of a sum of undesired interference levels in the first sector, the undesired interference levels being due to the frequency channels designated for all other sectors having a same carrier frequency as the first sector, the plot of the sum being determined as a function of the plurality of angles within the first sector.

61. The method of claim 60, wherein the step of calculating the ratio for the first sector includes a step of determining a plot of ratios of the desired signal level and the sum of the undesired interference levels in the first sector as a function of the plurality of angles within the first sector.