Interference control for CDMA networks using a plurality of narrow antenna beams and an estimation of the number of users/remote signals present

• US 6,118,767 A
• Filed: 11/19/1997
• Issued: 09/12/2000
• Est. Priority Date: 11/19/1997
• Status: Expired due to Term

• Current Assignee: Kathrein-Werke KG. (Kathrein SE)
• Original Assignee: Metawave Communications Corp.
• Inventors: Feuerstein, Martin J., Shen, Donglin
• Primary Examiner(s): Olms, Douglas W.
• Assistant Examiner(s): VINCENT, DAVID ROBERT
• Application Number:
  US08/974,592
• Time in Patent Office: 1,028 Days
• Field of Search: 370/320, 370/252, 370/328, 370/339, 370/342, 370/335, 455/522, 455/63, 455/501, 455/67.1, 455/67.3, 455/69, 455/115
• US Class Current: 370/252
• CPC Class Codes: H04B 1/7097 Interference-related aspects
• CPC Class Codes: H04B 17/309 Measuring or estimating channel quality parameters
• CPC Class Codes: H04B 17/327 Received signal code power [RSCP]
• CPC Class Codes: H04B 17/345 Interference values signal-to-interference ratio [SIR] or carrier-to-interference ratio [CIR] H04B17/336
• CPC Class Codes: H04B 17/354 Adjacent channel leakage power
• CPC Class Codes: H04W 16/24 Cell structures

Abstract

Systems and methods for providing mitigation of interference in a CDMA cellular network caused by excessive in band energy are disclosed. In the preferred embodiment, multiple narrow antenna beams are used to isolate the excessive energy from that of signals from mobile units. Control circuitry measures the power level on each of these multiple beams, compares this measurement to an estimated number of mobiles operating in the associated antenna beam, and determines if excessive energy is present in the beam. If excessive energy is determined to exist, the present invention causes the gain of particular antenna beams to be adjusted so as to mitigate the effect of the excessive energy.

Claims

1. A system for suppression of interference in a predefined frequency band as received on multiple narrow antenna beams, said system comprising:

means for determining whether excess energy within said predefined frequency band is present in at least one narrow antenna beam of said ones of said multiple narrow antenna beams, wherein said determination is a function of a measured received power and an estimation of a number of remote unit signals present; and

means for adjusting an attribute of a selected antenna beam signal of at least one narrow antenna beam of said ones of said multiple narrow antenna beams, wherein said adjusted antenna beam signal is selected as a function of said at least one narrow antenna beam determined to include excess energy, and wherein said adjustment is selected to provide said suppression of interference.

2. The system of claim 1, wherein said estimation of a number of remote unit signals present is made as a function of a measured received power level of a particular narrow antenna beam of said multiple narrow antenna beams and information with respect to a total number of remote unit signals in said ones of said multiple narrow antenna beams.

3. The system of claim 2, wherein said information with respect to said total number of remote unit signals is provided from a base station apparatus external to said system.

4. The system of claim 1, wherein said determination of excess energy in said at least one narrow antenna beam includes a comparison of a measured received power level of said at least one narrow antenna beam to a preselected threshold power level.

5. The system of claim 4, wherein said threshold power level is preselected as a function of said estimated number of remote unit signals received and a power level statistically determined to represent the power level of a single remote unit signal.

6. The system of claim 1, wherein said determination of excess energy in said at least one narrow antenna beam includes a comparison of reverse link loading estimates with forward link loading estimates.

7. The system of claim 1, wherein said determination of excess energy in said at least one narrow antenna beam includes a comparison of a relative power measurement of a portion of said predefined frequency band with a relative power measurement of said predefined frequency band.

8. The system of claim 7, wherein said power measurement of said portion of said predefined frequency band is made utilizing a narrow-band receiver.

9. The system of claim 7, wherein said power measurement of said portion of said predefined frequency band is made utilizing Fast Fourier Transform processing.

10. The system of claim 1, wherein said attribute of a selected antenna beam signal adjusted by said adjusting means is an amplitude.

11. The system of claim 10, wherein said amplitude adjustment is a reduction in gain of an antenna beam signal of said at least one narrow antenna beam determined to include excess energy.

12. The system of claim 10, wherein said amplitude adjustment is attenuation of an antenna beam signal of said at least one narrow antenna beam determined to include excess energy.

13. The system of claim 10, wherein said amplitude adjustment is an increase in gain of an antenna beam signal of said at least one narrow antenna beam other than said at least one narrow antenna beam determined to include excess energy.

14. The system of claim 10, wherein said amplitude adjustment is a first change in amplitude of an antenna beam signal of said at least one narrow antenna beam determined to include excess energy and a second change in amplitude of an antenna beam signal of a narrow antenna beam other than said at least one narrow antenna beam determined to include excess energy, wherein said first and second changes are converse amplitude adjustments.

15. The system of claim 10, wherein said amplitude adjustment includes attenuation of an antenna beam signal associated with said at least one narrow antenna beams determined to include excess energy to effectively interrupt transmission of said antenna beam signal.

16. The system of claim 1, wherein said attribute of a selected antenna beam signal adjusted by said adjusting means is a phase.

17. The system of claim 1, where said ones of said multiple narrow antenna beams are a set of said multiple narrow antenna beams defining a cellular network cell.

18. The system of claim 1, wherein said ones of said multiple narrow antenna beams are a set of said narrow antenna beams defining a sector of a cellular network cell.

19. A method for mitigating interference in a CDMA communication network, said CDMA communication network having at least one base station utilizing a plurality of narrow antenna beams each providing an antenna beam signal, said CDMA communication network also having a plurality of remote units in communication with said base station, said method comprising the steps of:

determining the presence of interference in excess of a preselected threshold in at least one antenna beam signal of said ones of said antenna beam signals, wherein said determination is made as a function of a measured preselected attribute of said at least one antenna beam signal and an estimated number of remote unit signals in said at least one antenna beam signal; and

adjusting an attribute of at least one antenna beam signal of said ones of said antenna beam signals, wherein said at least one antenna beam signal adjusted is selected as a function of said at least one antenna beam determined to include said excess interference.

20. The method of claim 19, wherein said estimation of a number of signals of said plurality of remote units present in a particular antenna beam signal is made as a function of said measured preselected attribute of said particular antenna beam signal and information with respect to a total number of remote unit signals in said ones of said antenna beam signals.

21. The method of claim 20, wherein said total number of remote unit signal information is provided from a base station apparatus selected from the group consisting of:

a scan receiver;

a base station controller; and

a demodulation receiver.

22. The method of claim 19, wherein said determining step includes the step of:

comparing a reverse link loading estimate with a forward link loading estimate.

23. The method of claim 19, wherein said measured preselected attribute is a receive power level.

24. The method of claim 23, wherein said estimation of a number of signals of said plurality of remote units present in a particular antenna beam signal is made as a function of a total number of remote unit signals in said ones of said antenna beam signals scaled by a fraction of said receive power level of said particular antenna beam signal to a sum of said receive power level of each of said ones of said antenna beam signals.

25. The method of claim 23, wherein said determining step comprises the step of:

comparing a receive power measurement of a portion of said predefined frequency band with a receive power measurement of said predefined frequency band.

26. The method of claim 25, wherein said receive power measurement of said portion of said predefined frequency band is made utilizing a narrow-band receiver.

27. The method of claim 25, wherein said receive power measurement of said portion of said predefined frequency band is made utilizing Fast Fourier Transform processing.

28. The method of claim 23, wherein said preselected threshold is a preselected threshold power level.

29. The method of claim 28, wherein said threshold power level is preselected as a function of said estimated number of remote unit signals received and a power level representative of the power level of a remote unit signal.

30. The method of claim 19, wherein said attribute of said selected antenna beam signal adjusted by said adjusting means is an amplitude.

31. The method of claim 30, wherein said amplitude adjustment is a reduction in gain of said antenna beam signal determined to include excess interference.

32. The method of claim 30, wherein said amplitude adjustment is attenuation of said antenna beam signal determined to include excess interference.

33. The method of claim 30, wherein said amplitude adjustment is an increase in gain of an antenna beam signal other than said at least one antenna beam signal determined to include excess interference.

34. The method of claim 30, wherein said amplitude adjustment includes attenuation substantially interrupting transmission of said antenna beam signal determined to include excess interference.

35. The method of claim 19, wherein said attribute of at least one antenna beam signal of said ones of said antenna beam signals adjusted by said adjusting means is a phase.

36. The method of claim 19, wherein said ones of said antenna beam signals are associated to define a cell.

37. The method of claim 19, wherein said ones of said antenna beam signals are associated to define a sector of a cell.

38. A system for mitigating interference experienced at a receiver in a CDMA cellular network, said CDMA cellular network having at least one base station utilizing a plurality of narrow antenna beams each providing an antenna beam signal suitable for use by said receiver, said CDMA cellular network also having a plurality of mobile units in communication with said base station, said system comprising:

antenna beam signal attribute adjustment circuitry providing independent adjustment of a preselected attribute of ones of said antenna beam signals;

antenna beam signal measurement circuitry coupled to ones of said multiple narrow antenna beams accepting said ones of said antenna beam signals, said measurement circuitry providing a measurement signal output including information with respect to measurement of said ones of said antenna beam signals, wherein said measurement signal output is a function of a measured received power and an estimation of a number of remote unit signals present; and

processor based controller circuitry coupled to said measurement circuitry accepting input of said measurement signal output, said controller circuitry also coupled to said adjustment circuitry and providing a control signal output thereto, wherein said controller circuitry provides at least one control signal output according to a predefined protocol to control said adjustment circuitry to adjust at least one selected antenna beam signal of said antenna beam signals as a function of said accepted measurement signal output.

39. The system of claim 38, wherein said measurement circuitry comprises:

a narrow-band receiver measuring receive power in a particular portion of a frequency band associated with said CDMA cellular network.

40. The system of claim 39, wherein said narrow-band receiver operates to scan various portions of said frequency band associated with said CDMA cellular network.

41. The system of claim 38, wherein said measurement circuitry comprises:

a wideband receiver coupled to circuitry detecting narrow-band interference.

42. The system of claim 41, wherein said narrow-band interference detection circuitry comprises a filter bank.

43. The system of claim 41, wherein said narrow-band interference detection circuitry comprises Fast Fourier Transform processing circuitry.

44. The system of claim 38, wherein said measurement circuitry comprises:

antenna beam traffic loading calculation circuitry providing a calculation of distribution of communication traffic associated with said plurality of mobile units on each of said ones of said antenna beam signals to said controller circuitry.

45. The system of claim 44, wherein said calculation of distribution of communication traffic includes a determination of forward link traffic and a determination of reverse link traffic, and wherein said protocol utilizes a comparison of said forward link and reverse link traffic determinations in adjusting said at least one selected antenna beam signal.

46. The system of claim 45, wherein said forward link traffic determination is made utilizing monitored information selected from the group consisting of:

a transmitted power;

a transmitted signal-to-interference ration;

a pilot channel measurement;

a demodulation utilization determination;

a modulation utilization determination;

a resource allocation determination; and

a back haul trunk utilization.

47. The system of claim 44, wherein said protocol utilizes said calculation of distribution of communication traffic in providing said plurality of control signal outputs to selected ones of said antenna beam signals.

48. The system of claim 47, wherein said protocol comprises a set of instructions operable to compare said measurement signal output for each of said ones of said antenna beam signals with a corresponding said calculation of distribution of communication traffic of said ones of said antenna beam signals, wherein said control signal output is a function of said comparison.

49. The system of claim 44, wherein said calculation circuitry is also coupled to circuitry external to said system and is adapted to accept a signal from said external circuitry.

50. The system of claim 49, wherein said external circuitry signal includes information with respect to a number of said mobile units communicating on said ones of said antenna beam signals.

51. The system of claim 38, further comprising:

interference detection circuitry, wherein said measurement circuitry measures a forward link power level and a reverse link power level, and wherein said detection circuitry utilizes a comparison of said forward and reverse link power levels in determining the presence of interference.

52. The system of claim 38, further comprising:

interference detection circuitry.

53. The system of claim 38, wherein said preselected attribute of said antenna beam signals adjusted is an amplitude.

54. The system of claim 53, wherein said adjustment circuitry includes a variable attenuator for each of said ones of said antenna beam signals.

55. The system of claim 53, wherein said adjustment circuitry includes a variable gain device for each of said ones of said antenna beam signals.

56. The system of claim 53, wherein said antenna beam signal attribute adjustment circuitry is also providing independent adjustment of a phase of ones of said antenna beam signals, and wherein said controller circuitry also provides a control signal output according to said predefined protocol to control a phase of an antenna beam signal.

57. The system of claim 38, wherein said measurement circuitry measures a power level of said ones of said antenna beam signals.

58. The system of claim 38, wherein said controller circuitry comprises a general purpose processor based system.

59. The system of claim 38, wherein said plurality of narrow antenna beams are 12 substantially 30°

non-overlapping antenna beams disposed azimuthally about said base station.