Methods for estimation and interference cancellation for signal processing

• US 8,005,128 B1
• Filed: 08/17/2007
• Issued: 08/23/2011
• Est. Priority Date: 09/23/2003
• Status: Expired due to Fees

• Current Assignee: III Holdings 1, LLC
• Original Assignee: Rambus Inc.
• Inventors: Lamba, Gagandeep Singh, Guess, Tommy, McCloud, Michael, Narayan, Anand P
• Primary Examiner(s): Tran, Khai
• Application Number:
  US11/893,707
• Time in Patent Office: 1,467 Days
• Field of Search: 375/144, 375/148, 375/130, 375/147, 375/347, 375/316, 375/346, 375/348, 375/349, 455/334
• US Class Current: 375/144
• CPC Class Codes: H04B 1/7097 Interference-related aspects
• CPC Class Codes: H04B 1/7107 Subtractive interference cancellation
• CPC Class Codes: H04B 1/71072 Successive interference cancellation
• CPC Class Codes: H04B 1/71075 Parallel interference cancellation
• CPC Class Codes: H04B 1/7115 Constructive combining of multi-path signals, i.e. RAKE receivers
• CPC Class Codes: H04B 1/7117 Selection, re-selection, allocation or re-allocation of paths to fingers, e.g. timing offset control of allocated fingers
• CPC Class Codes: H04B 15/00 Suppression or limitation of noise or interference by means associated with receiver H04B1/10
• CPC Class Codes: H04B 2001/71077 Partial interference cancellation
• CPC Class Codes: H04B 2201/709718 Determine interference
• CPC Class Codes: H04J 13/00 Code division multiplex systems for frequency hopping H04B1/713
• CPC Class Codes: H04J 13/0048 Walsh
• CPC Class Codes: H04L 43/08 Monitoring or testing based on specific metrics, e.g. QoS, energy consumption or environmental parameters
• CPC Class Codes: H04W 24/08 Testing, supervising or monitoring using real traffic

Abstract

A receiver in a CDMA system comprises a front end processor that generates a combined signal per source. A symbol estimator processes the combined signal to produce symbol estimates. An S-Matrix Generation module refines these symbol estimates based on the subchannel symbol estimates. An interference canceller is configured for cancelling interference from at least one of the plurality of received signals for producing at least one interference-cancelled signal.

Claims

1. A receiver comprising:

a front end comprising (i) a plurality of fingers and (ii) a finger combiner configured to combine a plurality of received signals from the plurality of fingers for producing a combined signal,

a symbol estimator configured to process the combined signal to produce a plurality of symbol estimates,

a symbol quality estimator configured for operating on the symbol estimates to generate symbol quality estimates based on said symbol estimates,

a processor that combines the symbol estimates with the said symbol quality estimates for at least one of a plurality of user subchannels, and

wherein the front end is configured to select fewer than all available signal paths and sectors for use in the symbol estimator.

2. The receiver recited in claim 1, further comprising a post-processing module configured for generating at least one interference vector.

3. The receiver in claim 1, further comprising an interference canceller configured for cancelling interference from at least one of the plurality of received signals for producing at least one interference-cancelled signal.

4. The receiver recited in claim 1, wherein the plurality of fingers comprises a single finger configured for processing multipaths in a Time Division Multiplex mode.

5. The receiver recited in claim 1, wherein the front end comprises a Rake receiver.

6. The receiver recited in claim 1, wherein the front end comprises an equalizer.

7. The receiver recited in claim 1, wherein the receiver further comprises an Alignment Calculator configured to output a global pseudo-noise (PN) sequence and alignments of PN sequences of each of the plurality of fingers with respect to the global PN sequence.

8. The receiver recited in claim 1, wherein the finger combiner is configured to weight at least one of the plurality of received signals.

9. The receiver recited in claim 1, further comprising a control unit configured to produce a routing decision based on estimated signal quality for each interference-cancelled signal and estimated signal quality from at least one of the plurality of received signals.

10. The receiver recited in claim 1, wherein the symbol estimator comprises a demultiplexer configured to separate data/preamble chips, Mac chips, and pilot chips, a Data/Preamble Discriminator to distinguish between data and preamble chips, and a Walsh decover block configured to produce the decovered data.

11. The receiver recited in claim 1, wherein the symbol quality estimator further comprises at least one filter configured for filtering at least one of the symbol estimates.

12. The receiver recited in claim 1, wherein the symbol quality estimator is configured for deriving an average signal strength over at least one of time and different Walsh codes.

13. The receiver recited in claim 3, wherein the interference canceller is configured for performing at least one of a projection and a subtraction.

14. The receiver recited in claim 3, further comprising a control unit configured to adapt the interference canceller for each channel depending on operating conditions.

15. The receiver recited in claim 1, where the symbol quality estimator generates at least one weight based on at least one of the symbol estimates.

16. The receiver recited in claim 1, where the symbol estimator uses a Fast Hadamard Transform to compute the symbol estimates.

17. The receiver recited in claim 1, where the symbol estimator uses a Fast Fourier Transform to compute the symbol estimates.

18. The receiver recited in claim 1, where the symbol quality estimator computes an SINR of at least one of the plurality of user subchannels.

19. The receiver recited in claim 1, where the symbol quality estimator uses knowledge of one or more known pilot bits to calculate a noise power.

20. The receiver recited in claim 1, where the symbol quality estimator uses estimates of at least one of the plurality of user subchannels and one or more noise power estimates to compute an interference power.

21. The receiver recited in claim 1, where the symbol estimator and an interference canceller are coupled serially from one source to another.

22. The receiver recited in claim 1, where the symbol estimator and an interference canceller are coupled in parallel for a plurality of sources.

23. A reception method comprising:

providing for combining a plurality of received signals from a plurality of fingers for producing a combined signal, wherein providing for combining a plurality of received signals from a plurality of fingers for producing a combined signal comprises selecting fewer than all available signal paths and sectors for use in producing a combined signal,

providing for processing the combined signal to produce symbol estimates,

providing for operating on the symbol estimates to generate symbol quality estimates, and

providing for combining the said symbol estimates with the said symbol quality estimates for at least one of a plurality of user subchannels.

24. The method recited in claim 23, further comprising providing for generating at least one interference vector.

25. The method recited in claim 23, further comprising providing for cancelling interference from at least one of the plurality of received signals for producing at least one interference-cancelled signal.

26. The method recited in claim 23, wherein providing for combining employs a single finger configured for processing multipaths in a Time Division Multiplex mode.

27. The method recited in claim 23, wherein providing for combining employs a Rake receiver.

28. The method recited in claim 23, wherein providing for combining employs an equalizer.

29. The method recited in claim 23, wherein providing for combining further comprises producing a global pseudo-noise (PN) sequence and alignments of PN sequences of each of the plurality of fingers with respect to the global PN sequence.

30. The method recited in claim 23, wherein providing for combining further comprises weighting at least one of the plurality of received signals.

31. The method recited in claim 23, further comprising producing a routing decision based on estimated signal quality for each interference-cancelled signal and estimated signal quality from at least one of the plurality of received signals.

32. The method recited in claim 23, wherein providing for processing the combined signal to produce symbol estimates further comprises separating data/preamble chips, Mac chips, and pilot chips, distinguishing between data and preamble chips, and performing Walsh decovering to produce the decovered data.

33. The method recited in claim 23, wherein providing for selecting further comprises filtering at least one of the symbol estimates.

34. The method recited in claim 23, wherein providing for selecting further comprises deriving an average signal strength over at least one of time and a plurality of Walsh codes.

35. The method recited in claim 23, wherein providing for cancelling comprises performing at least a projection operation or a subtraction.

36. The method recited in claim 23, further comprising adapting cancellation for each channel depending on operating conditions.

37. The method recited in claim 23, where providing for operating on the symbol estimates to generate symbol quality estimates comprises generating at least one weight based on the symbol estimates.

38. The method recited in claim 23, where providing for processing the combined signal to produce symbol estimates comprises using a Fast Hadamard Transform to compute the symbol estimates.

39. The method recited in claim 23, where providing for processing the combined signal to produce symbol estimates comprises using a Fast Fourier Transform to compute the symbol estimates.

40. The method recited in claim 23, where providing for operating on the symbol estimates to generate symbol quality estimates comprises computing an SINR of at least one of the plurality of user subchannels.

41. The method recited in claim 23, where providing for operating on the symbol estimates to generate symbol quality estimates comprises using knowledge of one or more known pilot bits to calculate a noise power.

42. The method recited in claim 23, where providing for operating on the symbol estimates to generate symbol quality estimates comprises using estimates of a plurality of subchannels and one or more noise power estimates to compute an interference power.

43. The method of claim 25, where providing for cancelling interference is performed serially from one source to another.

44. The method of claim 25, where providing for cancelling interference is performed in parallel for a plurality of sources.

45. A handset configured to perform the method recited in claim 23.

46. A chipset configured to perform the method recited in claim 23.

47. A digital computer system programmed to perform the method recited in claim 23.

48. A computer-readable medium storing a computer program implementing the method of claim 23.

49. A base station configured to perform the method of claim 23.

50. A receiver system comprising:

a combining means configured for combining a plurality of received signals from a plurality of fingers for producing a combined signal, wherein the combining means comprises means for selecting fewer than all available signal paths and sectors for use in producing the combined signal,

a symbol estimation means configured for processing the combined signal to produce symbol estimates,

a symbol quality estimation means configured for operating on the symbol estimates to generate symbol quality estimates, and

a means for combining said symbol estimates with the said symbol quality estimates for at least one of a plurality of user subchannels.

51. The system recited in claim 50, further comprising a means for generating at least one interference vector.

52. The system recited in claim 50, further comprising a means for interference cancellation configured for cancelling interference from at least one of the plurality of received signals for producing at least one interference-cancelled signal.

53. The system recited in claim 50, wherein the combining means comprises a single finger configured for processing multipaths in a Time Division Multiplex mode.

54. The system recited in claim 50, wherein the combining means comprises a Rake receiver.

55. The system recited in claim 50, wherein the combining means comprises an equalizer.

56. The system recited in claim 50, wherein the combining means is further configured for producing a global pseudo-noise (PN) sequence and alignments of PN sequences of each of the plurality of fingers with respect to the global PN sequence.

57. The system recited in claim 50, wherein the combining means further comprises a weighting means configured for weighting at least one of the plurality of received signals.

58. The system recited in claim 50, further comprising a routing means configured to produce a routing decision based on estimated signal quality for each interference-cancelled signal and estimated signal quality from at least one of the plurality of received signals.

59. The system recited in claim 50, wherein the combining means is further configured for separating data/preamble chips, Mac chips, and pilot chips, distinguishing between data and preamble chips, and performing Walsh decovering to produce the decovered data.

60. The system recited in claim 50, wherein the symbol quality estimation means is further configured for filtering at least one of the symbol estimates.

61. The system recited in claim 50, wherein the symbol quality estimation means is further configured for deriving an average signal strength over at least one of time and a plurality of Walsh codes.

62. The system recited in claim 50, wherein the means for interference cancellation is configured for performing at least one of a projection and a subtraction.

63. The system recited in claim 50, wherein the means for interference cancellation is configured for adapting cancellation for each channel depending on operating conditions.

64. The system recited in claim 50, where the symbol quality estimation means comprises means for generating at least one weight based on the symbol estimates.

65. The system recited in claim 50, where the symbol estimation means comprises means for using a Fast Hadamard Transform to compute the symbol estimates.

66. The system recited in claim 50, where the symbol estimation means comprises means for using a Fast Fourier Transform to compute the symbol estimates.

67. The system recited in claim 50, where symbol quality estimation means comprises means for computing an SINR of at least one of the plurality of user subchannels.

68. The system recited in claim 50, where symbol quality estimation means comprises means for using knowledge of one or more known pilot bits to calculate a noise power.

69. The system recited in claim 50, where symbol quality estimation means comprises means for using estimates of a plurality of subchannels and one or more noise power estimates to compute an interference power.

70. The system recited in claim 52, where means for interference cancellation is performed serially from one source to another.

71. The system recited in claim 52, where means for interference cancellation is performed in parallel for a plurality of sources.