Multipath equalization for MIMO multiuser systems

• US 20030026345A1
• Filed: 06/17/2002
• Published: 02/06/2003
• Est. Priority Date: 06/15/2001
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Onggosanusi, Eko, Dabak, Anand, Muharemovic, Tarik
• Granted Patent: US 7,933,342 B2
• Time in Patent Office: Days
• US Class Current: 375/260
• CPC Class Codes: H04B 1/71072 Successive interference cancellation
• CPC Class Codes: H04L 1/06 using space diversity
• CPC Class Codes: H04L 2025/03624 Zero-forcing
• CPC Class Codes: H04L 25/03178 Arrangements involving sequence estimation techniques

Abstract

Interference rejection (85) can be applied to a wireless communication signal with reduced computational complexity by producing from a sample vector (y) a plurality of vectors (w) that are smaller than the sample vector. The interference rejection operation can then be applied to each of the smaller vectors individually to decide communication symbols represented by the sample vector.

Claims

1. An apparatus for processing a received wireless communication signal, comprising:

an input for receiving a sample vector which includes a plurality of sample values and which represents a timewise corresponding wireless communication signal portion received via a plurality of receive antennas and produced by a transmitter in which each of a plurality of information sources transmits a plurality of symbols via respective ones of a plurality of transmit antennas during each of a plurality of transmit time intervals associated with said wireless communication signal portion;

an input processing section coupled to said input for producing from the sample vector a plurality of vectors that are smaller than the sample vector; and

an interference rejection unit coupled to said input processing section for applying an interference rejection operation to each of said smaller vectors individually to thereby decide said symbols.

2. The apparatus of claim 1, wherein said input processing section includes a chip equalizer coupled to said input for applying a chip equalization operation to said sample vector to thereby produce a chip equalization result vector.

3. The apparatus of claim 2, wherein said input processing section includes a separator coupled to said chip equalizer for separating said chip equalization result vector into a plurality of intermediate vectors.

4. The apparatus of claim 3, wherein said input processing section includes a despreader coupled between said interference rejection unit and said separator for applying a plurality of spreading codes to said intermediate vectors to effectuate a despreading operation that produces said smaller vectors.

5. The apparatus of claim 4, wherein said intermediate vectors respectively correspond to said transmit time intervals, and wherein each of said smaller vectors corresponds to a respective one of said information sources during a respective one of said transmit time intervals.

6. The apparatus of claim 3, wherein said intermediate vectors respectively correspond to said transmit time intervals.

7. The apparatus of claim 2, wherein said chip equalization operation includes one of a zero-forcing chip equalization operation and a minimum mean squared error chip equalization operation.

8. The apparatus of claim 7, wherein said interference rejection operation includes one of a successive interference cancellation operation and a maximum likelihood detection operation.

9. The apparatus of claim 8, wherein said successive interference cancellation operation includes one of a zero-forcing successive interference cancellation operation and a minimum mean squared error successive interference cancellation operation.

10. The apparatus of claim 2, wherein said input processing section includes a despreader coupled to said chip equalizer for applying a plurality of spreading codes to said chip equalization result vector to effectuate a despreading operation that produces an intermediate vector.

11. The apparatus of claim 10, wherein said input processing section includes a separator coupled to said despreader for separating said intermediate vector into a plurality of further vectors.

12. The apparatus of claim 11, wherein each said further vector corresponds to a respective one of said information sources during a respective one of said transmit time intervals.

13. The apparatus of claim 11, wherein said further vectors are said smaller vectors.

14. The apparatus of claim 11, wherein said input processing section includes a preconditioner coupled between said separator and said interference rejection unit for processing said further vectors to whiten respective noise components thereof and thereby produce a corresponding plurality of preconditioned vectors whose respective noise components are white.

15. The apparatus of claim 14, wherein said preconditioned vectors are said smaller vectors.

16. The apparatus of claim 1, wherein said interference rejection operation includes one of a successive interference cancellation operation and a maximum likelihood detection operation.

17. The apparatus of claim 16, wherein said successive interference cancellation operation includes one of a zero-forcing successive interference cancellation operation and a minimum mean squared error successive interference cancellation operation.

18. The apparatus of claim 1, wherein said input processing section includes a multi-user detector coupled to said input for applying a multi-user detection operation to said sample vector to produce a multi-user detection result vector.

19. The apparatus of claim 18, wherein said input processing section includes a separator coupled to said multi-user detector for separating said multi-user detection result vector into a plurality of further vectors.

20. The apparatus of claim 19, wherein each said further vector corresponds to a respective one of said information sources during a respective one of said transmit time intervals.

21. The apparatus of claim 19, wherein said further vectors are said smaller vectors.

22. The apparatus of claim 19, wherein said input processing section includes a preconditioner coupled between said separator and said interference rejection unit for processing said further vectors to whiten respective noise components thereof and thereby produce a corresponding plurality of preconditioned vectors whose respective noise components are white.

23. The apparatus of claim 22, wherein said preconditioned vectors are said smaller vectors.

24. The apparatus of claim 18, wherein said multi-user detection operation is one of a zero-forcing multi-user detection operation and a minimum mean squared error multi-user detection operation.

25. The apparatus of claim 24, wherein said interference rejection operation includes one of a successive interference cancellation operation and a maximum likelihood detection operation.

26. The apparatus of claim 25, wherein said successive interference cancellation operation is one of a zero-forcing successive interference cancellation operation and a minimum mean squared error successive interference cancellation operation.

27. The apparatus of claim 1, wherein said interference rejection unit is for applying said interference rejection operation to each of said smaller vectors simultaneously.

28. A wireless communication receiving apparatus, comprising:

a plurality of receive antennas for receiving a wireless communication signal;

a sampler coupled to said receive antennas for producing a sample vector which includes a plurality of sample values and which represents a timewise corresponding portion of said wireless communication signal, said wireless communication signal portion produced by a transmitter in which each of a plurality of information sources transmits a plurality of symbols via respective ones of a plurality of transmit antennas during each of a plurality of transmit time intervals associated with said wireless communication signal portion;

an input processing section coupled to said sampler for producing from said sample vector a plurality of vectors that are smaller than said sample vector;

an interference rejection unit coupled to said input processing section for applying an interference rejection operation to each of said smaller vectors individually to thereby decide said symbols;

a data extractor coupled to said interference rejection unit for extracting communication data from the symbols decided by said interference rejection unit; and

a data processing apparatus coupled to said data extractor for performing data processing operations on said extracted data.

29. The apparatus of claim 28, provided as a CDMA receiver.

30. The apparatus of claim 28, wherein said input processing section includes a chip equalizer coupled to said input for applying a chip equalization operation to said sample vector to thereby produce a chip equalization result vector.

31. The apparatus of claim 30, wherein said input processing section includes a separator coupled to said chip equalizer for separating said chip equalization result vector into a plurality of intermediate vectors.

32. The apparatus of claim 31, wherein said input processing section includes a despreader coupled between said interference rejection unit and said separator for applying a plurality of spreading codes to said intermediate vectors to effectuate a despreading operation that produces said smaller vectors.

33. The apparatus of claim 32, wherein said intermediate vectors respectively correspond to said transmit time intervals, and wherein each of said smaller vectors corresponds to a respective one of said information sources during a respective one of said transmit time intervals.

34. The apparatus of claim 31, wherein said intermediate vectors respectively correspond to said transmit time intervals.

35. The apparatus of claim 30, wherein said input processing section includes a despreader coupled to said chip equalizer for applying a plurality of spreading codes to said chip equalization result vector to effectuate a despreading operation that produces an intermediate vector.

36. The apparatus of claim 35, wherein said input processing section includes a separator coupled to said despreader for separating said intermediate vector into a plurality of further vectors.

37. The apparatus of claim 36, wherein each said further vector corresponds to a respective one of said information sources during a respective one of said transmit time intervals.

38. The apparatus of claim 36, wherein said further vectors are said smaller vectors.

39. The apparatus of claim 36, wherein said input processing section includes a preconditioner coupled between said separator and said interference rejection unit for processing said further vectors to whiten respective noise components thereof and thereby produce a corresponding plurality of preconditioned vectors whose respective noise components are white.

40. The apparatus of claim 39, wherein said preconditioned vectors are said smaller vectors.

41. The apparatus of claim 28, wherein said input processing section includes a multi-user detector coupled to said input for applying a multi-user detection operation to said sample vector to produce a multi-user detection result vector.

42. The apparatus of claim 41, wherein said input processing section includes a separator coupled to said multi-user detector for separating said multi-user detection result vector into a plurality of further vectors.

43. The apparatus of claim 42, wherein each said further vector corresponds to a respective one of said information sources during a respective one of said transmit time intervals.

44. The apparatus of claim 42, wherein said further vectors are said smaller vectors.

45. The apparatus of claim 42, wherein said input processing section includes a preconditioner coupled between said separator and said interference rejection unit for processing said further vectors to whiten respective noise components thereof and thereby produce a corresponding plurality of preconditioned vectors whose respective noise components are white.

46. The apparatus of claim 45, wherein said preconditioned vectors are said smaller vectors.

47. The apparatus of claim 28, wherein said interference rejection unit is for applying said interference rejection operation to each of said smaller vectors simultaneously.

48. A method of processing a received wireless communication signal, comprising:

receiving a wireless communication signal via a plurality of receive antennas;

producing a sample vector which includes a plurality of sample values and which represents a timewise corresponding portion of said wireless communication signal, said wireless communication signal portion produced by a transmitter in which each of a plurality of information sources transmits a plurality of symbols via respective ones of a plurality of transmit antennas during each of a plurality of transmit time intervals associated with said wireless communication signal portion;

producing from said sample vector a plurality of vectors that are smaller than said sample vector; and

applying an interference rejection operation to each of said smaller vectors individually to thereby decide said symbols.

49. The method of claim 48, wherein said last-mentioned producing step includes applying a chip equalization operation to said sample vector to thereby produce a chip equalization result vector.

50. The apparatus of claim 49, wherein said last-mentioned producing step includes separating said chip equalization result vector into a plurality of intermediate vectors.

51. The apparatus of claim 50, wherein said last-mentioned producing step includes applying a plurality of spreading codes to said intermediate vectors to effectuate a despreading operation that produces said smaller vectors.

52. The apparatus of claim 51, wherein said intermediate vectors respectively correspond to said transmit time intervals, and wherein each of said smaller vectors corresponds to a respective one of said information sources during a respective one of said transmit time intervals.

53. The method of claim 50, wherein said intermediate vectors respectively correspond to said transmit time intervals.

54. The method of claim 49, wherein said last-mentioned producing step includes applying a plurality of spreading codes to said chip equalization result vector to effectuate a despreading operation that produces an intermediate vector.

55. The method of claim 54, wherein said last-mentioned producing step includes separating said intermediate vector into a plurality of further vectors.

56. The method of claim 55, wherein each said further vector corresponds to a respective one of said information sources during a respective one of said transmit time intervals.

57. The method of claim 55, wherein said further vectors are said smaller vectors.

58. The method of claim 55, wherein said last-mentioned producing step includes preconditioning said further vectors, including processing said further vectors to whiten respective noise components thereof and thereby produce a corresponding plurality of preconditioned vectors whose respective noise components are white.

59. The method of claim 58, wherein said preconditioned vectors are said smaller vectors.

60. The method of claim 48, wherein said last-mentioned producing step includes applying a multi-user detection operation to said sample vector to produce a multi-user detection result vector.

61. The method of claim 60, wherein said last-mentioned producing step includes separating said multi-user detection result vector into a plurality of further vectors.

62. The method of claim 61, wherein each said further vector corresponds to a respective one of said information sources during a respective one of said transmit time intervals.

63. The method of claim 61, wherein said further vectors are said smaller vectors.

64. The method of claim 61, wherein said last-mentioned producing step includes preconditioning said further vectors, including processing said further vectors to whiten respective noise components thereof and thereby produce a corresponding plurality of preconditioned vectors whose respective noise components are white.

65. The method of claim 64, where said preconditioned vectors are said smaller vectors.

66. The method of claim 48, wherein said applying step includes applying said interference rejection operation to each of said smaller vectors simultaneously.

67. The method of claim 48, wherein said interference rejection operation includes one of a successive interference cancellation operation and a maximum likelihood detection operation.

68. A wireless communication receiver apparatus, comprising:

a receive antenna apparatus for receiving a wireless communication signal;

a sampler coupled to said receive antenna apparatus for producing a sample vector which includes a plurality of sample values and which represents a timewise corresponding portion of said wireless communication signal;

a linear front end detector coupled to said sampler for applying a detection operation to said sample vector to produce a detection result vector;

an interference rejection unit coupled to said linear front end detector for applying an interference rejection operation to information from said detection result vector to make decisions regarding symbols carried by said wireless communication signal portion;

a data extractor coupled to said interference rejection unit for extracting communication data from the symbols decided by said interference rejection unit;

and a data processing apparatus coupled to said data extractor for performing data processing operations on said extracted data.

69. The apparatus of claim 68, wherein said linear front end detector includes a chip equalizer and said detection operation includes a chip equalization operation.

70. The apparatus of claim 69, wherein said chip equalization operation is one of a zero-forcing chip equalization operation and a minimum mean squared error chip equalization operation.

71. The apparatus of claim 68, wherein said linear front end detector includes a multi-user detector, and said detection operation includes a multi-user detection operation.

72. The apparatus of claim 71, wherein said multi-user detection operation is one of a zero-forcing multi-user detection operation and a minimum mean squared error multi-user detection operation.

73. The apparatus of claim 68, provided as a CDMA receiver.

74. The apparatus of claim 68, wherein said interference rejection operation is one of a successive interference cancellation operation and a maximum likelihood detection operation.

75. The apparatus of claim 74, wherein said successive interference cancellation operation is one of a zero-forcing successive interference cancellation operation and a minimum mean squared error successive interference cancellation operation.

76. The apparatus of claim 68, including a separating portion coupled to said linear front end detector for producing from said detection result vector a plurality of vectors that are smaller than said detection result vector, said interference rejection unit for applying said interference rejection operation to each of said smaller vectors individually.

77. The apparatus of claim 76, wherein said interference rejection unit is for applying said interference rejection operation to each of said smaller vectors simultaneously.

78. The apparatus of claim 76, wherein said separating portion includes a despreader.

79. An apparatus for processing a received wireless communication signal, comprising:

an input for receiving a sample vector which includes a plurality of sample values and which represents a timewise corresponding portion of a wireless communication signal received via a receive antenna apparatus;

a linear front end detector coupled to said input for applying a detection operation to said sample vector to produce a detection result vector; and

an interference rejection unit coupled to said linear front end detector for applying an interference rejection operation to said detection result vector to make decisions regarding symbols carried by said wireless communication signal portion.

80. The apparatus of claim 79, wherein said linear front end detector includes a chip equalizer and said detection operation includes a chip equalization operation.

81. The apparatus of claim 80, wherein said chip equalization operation is one of a zero-forcing chip equalization operation and a minimum mean squared error chip equalization operation.

82. The apparatus of claim 79, wherein said linear front end detector includes a multi-user detector, and said detection operation includes a multi-user detection operation.

83. The apparatus of claim 82, wherein said multi-user detection operation is one of a zero-forcing multi-user detection operation and a minimum mean squared error multi-user detection operation.

84. The apparatus of claim 79, wherein said interference rejection operation is one of a successive interference cancellation operation and a maximum likelihood detection operation.

85. The apparatus of claim 84, wherein said successive interference cancellation operation is one of a zero-forcing successive interference cancellation operation and a minimum mean squared error successive interference cancellation operation.

86. The apparatus of claim 79, including a separating portion coupled to said linear front end detector for producing from said detection result vector a plurality of vectors that are smaller than said detection result vector, said interference rejection unit for applying said interference rejection operation to each of said smaller vectors individually.

87. The apparatus of claim 86, wherein said interference rejection unit is for applying said interference rejection operation to each of said smaller vectors simultaneously.

88. The apparatus of claim 86, wherein said separating portion includes a despreader.