Joint channel equalizer interference canceller advanced receiver

• US 20050153663A1
• Filed: 10/29/2004
• Published: 07/14/2005
• Est. Priority Date: 10/30/2003
• Status: Active Grant

• Current Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Original Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Inventors: Tsai, Yingming, Pan, Jung-Lin, DiFazio, Robert A.
• Granted Patent: US 7,437,135 B2
• Time in Patent Office: Days
• US Class Current: 455/78
• CPC Class Codes: H04B 7/0845 per branch equalization, e.g. by an FIR-filter or RAKE receiver per antenna branch rake receivers as such H04B1/7115
• CPC Class Codes: H04L 2025/03375 Passband transmission
• CPC Class Codes: H04L 2025/03477 not time-recursive

Abstract

At least one communication is transmitted from a plurality of transmitting antennas. A signal is received. For each transmitting antenna, the received signal is equalized with respect to a channel experience by the communication between the transmitting antenna and the signal receiving, producing symbols. A contribution of that transmitting antenna to the received signal is constructed using the produced symbols. The contribution of that transmitting antenna is subtracted from the received signal for use in further equalization of the received signal with respect to others of the transmitting antennas.

Claims

1. A method for receiving at least one communication transmitted from a plurality of transmitting antennas, the method comprising:

receiving a signal;

for each transmitting antenna;

equalizing the received signal with respect to a channel experience by the communication between the transmitting antenna and the receiving, producing symbols;

constructing a contribution of that transmitting antenna to the received signal using the produced symbols; and

subtracting the contribution of that transmitting antenna from the received signal for use in further equalization of the received signal with respect to others of the transmitting antennas.

2. The method of claim 1 utilizing successive interference cancellation, such that the equalizing the received signal with respect to one of the transmitting antennas and that one transmitting antennas contribution is cancelled from the received signal prior to the equalizing with respect to others of the transmitting antennas.

3. The method of claim 1 utilizing parallel interference cancellation, such that the equalizing the received signal with respect to all of the transmitting antennas is performed prior to canceling a contribution of any of the transmitting antennas from the received signal.

4. The method of claim 1 further comprising selectively uses either successive interference cancellation (SIC) or parallel interference cancellation (PIC), for SIC the equalizing the received signal with respect to one of the transmitting antennas and that one transmitting antennas contribution is cancelled from the received signal prior to the equalizing with respect to others of the transmitting antennas, and for PIC the equalizing the received signal with respect to all of the transmitting antennas is performed prior to canceling a contribution of any of the transmitting antennas from the received signal.

5. The method of claim 4 further comprising measuring a channel power of each transmitting antenna, comparing the measured channel power for each transmitting antenna and based on the comparison, determining whether SIC or PIC is to be selected.

6. The method of claim 5 wherein if the measured channel power for each transmitting antenna is within a threshold, selecting PIC and if the measured channel power for each transmitting antenna is not within the threshold, selecting SIC.

7. The method of claim 6 wherein if SIC is selected, the equalizing with respect to the channel of the transmitting antenna having a highest power level is performed prior to the other transmitting antennas.

8. The method of claim 1 wherein the at least one communication includes a plurality of codes and the equalizing is performed collectively on all the codes.

9. The method of claim 1 wherein the at least one communication includes a plurality of codes and the equalizing is performed sequentially on each code individually.

10. The method of claim 1 wherein the at least one communication includes a plurality of codes and the plurality of codes are grouped into code groups, at least one code group having more than one code and the equalizing is performed sequentially on each code individually.

11. The method of claim 1 wherein the produced symbols are spread symbols.

12. The method of claim 11 wherein the produces spread symbols are despread.

13. The method of claim 12 wherein the despread symbols with respect to the transmitting antenna having the largest receiver signal to interference/noise level is selected over the despread symbols of others of the transmitting antennas.

14. The method of claim 12 wherein the despread symbols for all the transmitting antenna are combined.

15. The method of claim 14 wherein the combining is performed by maximum ratio combining.

16. A wireless transmit/receive unit (WTRU) for receiving at least one communication transmitted from a plurality of transmitting antennas, the WTRU comprising:

means for receiving a signal;

for each transmitting antenna;

means for equalizing the received signal with respect to a channel experience by the communication between the transmitting antenna and the receiving, producing symbols;

means for constructing a contribution of that transmitting antenna to the received signal using the produced symbols; and

means for subtracting the contribution of that transmitting antenna from the received signal for use in further equalization of the received signal with respect to others of the transmitting antennas.

17. The WTRU of claim 16 utilizing successive interference cancellation, such that the equalizing the received signal with respect to one of the transmitting antennas and that one transmitting antennas contribution is cancelled from the received signal prior to the equalizing with respect to others of the transmitting antennas.

18. The WTRU of claim 16 utilizing parallel interference cancellation, such that the equalizing the received signal with respect to all of the transmitting antennas is performed prior to canceling a contribution of any of the transmitting antennas from the received signal.

19. The WTRU of claim 16 further comprising means for selectively using either successive interference cancellation (SIC) or parallel interference cancellation (PIC), for SIC the equalizing the received signal with respect to one of the transmitting antennas and that one transmitting antennas contribution is cancelled from the received signal prior to the equalizing with respect to others of the transmitting antennas, and for PIC the equalizing the received signal with respect to all of the transmitting antennas is performed prior to canceling a contribution of any of the transmitting antennas from the received signal.

20. The WTRU of claim 16 further comprising means for measuring a channel power of each transmitting antenna, means for comparing the measured channel power for each transmitting antenna and means based on the comparison, for determining whether SIC or PIC is to be selected.

21. The WTRU of claim 20 wherein if the measured channel power for each transmitting antenna is within a threshold, selecting PIC and if the measured channel power for each transmitting antenna is not within the threshold, selecting SIC.

22. The WTRU of claim 21 wherein if SIC is selected, the equalizing with respect to the channel of the transmitting antenna having a highest power level is performed prior to the other transmitting antennas.

23. The WTRU of claim 16 wherein the at least one communication includes a plurality of codes and the equalizing is performed collectively on all the codes.

24. The WTRU of claim 16 wherein the at least one communication includes a plurality of codes and the equalizing is performed sequentially on each code individually.

25. The WTRU of claim 16 wherein the at least one communication includes a plurality of codes and the plurality of codes are grouped into code groups, at least one code group having more than one code and the equalizing is performed sequentially on each code individually.

26. The WTRU of claim 16 wherein the produced symbols are spread symbols.

27. The WTRU of claim 26 further comprising means for despreading the spread symbols.

28. The WTRU of claim 27 wherein the despread symbols with respect to the transmitting antenna having the largest receiver signal to interference/noise level is selected over the despread symbols of others of the transmitting antennas.

29. The WTRU of claim 27 wherein the despread symbols for all the transmitting antenna are combined.

30. The WTRU of claim 29 wherein the combining is performed by maximum ratio combining.

31. A wireless transmit/receive unit (WTRU) for receiving at least one communication transmitted from a plurality of transmitting antennas, the WTRU comprising:

an antenna for receiving a signal;

for each transmitting antenna;

an equalizer for equalizing the received signal with respect to a channel experience by the communication between the transmitting antenna and the receiving, producing symbols;

an interference construction device for constructing a contribution of that transmitting antenna to the received signal using the produced symbols; and

a subtractor for subtracting the contribution of that transmitting antenna from the received signal for use in further equalization of the received signal with respect to others of the transmitting antennas.

32. The WTRU of claim 31 utilizing successive interference cancellation, such that the equalizing the received signal with respect to one of the transmitting antennas and that one transmitting antennas contribution is cancelled from the received signal prior to the equalizing with respect to others of the transmitting antennas.

33. The WTRU of claim 31 utilizing parallel interference cancellation, such that the equalizing the received signal with respect to all of the transmitting antennas is performed prior to canceling a contribution of any of the transmitting antennas from the received signal.

34. The WTRU of claim 31 further comprising a SIC/PIC control unit for selectively using either successive interference cancellation (SIC) or parallel interference cancellation (PIC), for SIC the equalizing the received signal with respect to one of the transmitting antennas and that one transmitting antennas contribution is cancelled from the received signal prior to the equalizing with respect to others of the transmitting antennas, and for PIC the equalizing the received signal with respect to all of the transmitting antennas is performed prior to canceling a contribution of any of the transmitting antennas from the received signal.

35. The WTRU of claim 31 further comprising a power measuring device for measuring a channel power of each transmitting antenna, means for comparing the measured channel power for each transmitting antenna and means based on the comparison, for determining whether SIC or PIC is to be selected.

36. The WTRU of claim 35 wherein if the measured channel power for each transmitting antenna is within a threshold, selecting PIC and if the measured channel power for each transmitting antenna is not within the threshold, selecting SIC.

37. The WTRU of claim 36 wherein if SIC is selected, the equalizing with respect to the channel of the transmitting antenna having a highest power level is performed prior to the other transmitting antennas.

38. The WTRU of claim 31 wherein the at least one communication includes a plurality of codes and the equalizing is performed collectively on all the codes.

39. The WTRU of claim 31 wherein the at least one communication includes a plurality of codes and the equalizing is performed sequentially on each code individually.

40. The WTRU of claim 31 wherein the at least one communication includes a plurality of codes and the plurality of codes are grouped into code groups, at least one code group having more than one code and the equalizing is performed sequentially on each code individually.

41. The WTRU of claim 31 wherein the produced symbols are spread symbols.

42. The WTRU of claim 41 further comprising at least one despreader for despreading the spread symbols.

43. The WTRU of claim 42 wherein the despread symbols with respect to the transmitting antenna having the largest receiver signal to interference/noise level is selected over the despread symbols of others of the transmitting antennas.

44. The WTRU of claim 42 wherein the despread symbols for all the transmitting antenna are combined.

45. The WTRU of claim 44 wherein the combining is performed by maximum ratio combining.

46. A base station for receiving at least one communication transmitted from a plurality of transmitting antennas, the base station comprising:

means for receiving a signal;

for each transmitting antenna;

means for equalizing the received signal with respect to a channel experience by the communication between the transmitting antenna and the receiving, producing symbols;

means for constructing a contribution of that transmitting antenna to the received signal using the produced symbols; and

means for subtracting the contribution of that transmitting antenna from the received signal for use in further equalization of the received signal with respect to others of the transmitting antennas.

47. The base station of claim 46 utilizing successive interference cancellation, such that the equalizing the received signal with respect to one of the transmitting antennas and that one transmitting antennas contribution is cancelled from the received signal prior to the equalizing with respect to others of the transmitting antennas.

48. The base station of claim 46 utilizing parallel interference cancellation, such that the equalizing the received signal with respect to all of the transmitting antennas is performed prior to canceling a contribution of any of the transmitting antennas from the received signal.

49. The base station of claim 46 further comprising means for selectively using either successive interference cancellation (SIC) or parallel interference cancellation (PIC), for SIC the equalizing the received signal with respect to one of the transmitting antennas and that one transmitting antennas contribution is cancelled from the received signal prior to the equalizing with respect to others of the transmitting antennas, and for PIC the equalizing the received signal with respect to all of the transmitting antennas is performed prior to canceling a contribution of any of the transmitting antennas from the received signal.

50. The base station of claim 46 further comprising means for measuring a channel power of each transmitting antenna, means for comparing the measured channel power for each transmitting antenna and means based on the comparison, for determining whether SIC or PIC is to be selected.

51. The base station of claim 50 wherein if the measured channel power for each transmitting antenna is within a threshold, selecting PIC and if the measured channel power for each transmitting antenna is not within the threshold, selecting SIC.

52. The base station of claim 51 wherein if SIC is selected, the equalizing with respect to the channel of the transmitting antenna having a highest power level is performed prior to the other transmitting antennas.

53. The base station of claim 46 wherein the at least one communication includes a plurality of codes and the equalizing is performed collectively on all the codes.

54. The base station of claim 46 wherein the at least one communication includes a plurality of codes and the equalizing is performed sequentially on each code individually.

55. The base station of claim 46 wherein the at least one communication includes a plurality of codes and the plurality of codes are grouped into code groups, at least one code group having more than one code and the equalizing is performed sequentially on each code individually.

56. The base station of claim 46 wherein the produced symbols are spread symbols.

57. The base station of claim 56 further comprising means for despreading the spread symbols.

58. The base station of claim 57 wherein the despread symbols with respect to the transmitting antenna having the largest receiver signal to interference/noise level is selected over the despread symbols of others of the transmitting antennas.

59. The base station of claim 57 wherein the despread symbols for all the transmitting antenna are combined.

60. The base station of claim 59 wherein the combining is performed by maximum ratio combining.

61. A base station for receiving at least one communication transmitted from a plurality of transmitting antennas, the base station comprising:

an antenna for receiving a signal;

for each transmitting antenna;

an equalizer for equalizing the received signal with respect to a channel experience by the communication between the transmitting antenna and the receiving, producing symbols;

an interference construction device for constructing a contribution of that transmitting antenna to the received signal using the produced symbols; and

a subtractor for subtracting the contribution of that transmitting antenna from the received signal for use in further equalization of the received signal with respect to others of the transmitting antennas.

62. The base station of claim 61 utilizing successive interference cancellation, such that the equalizing the received signal with respect to one of the transmitting antennas and that one transmitting antennas contribution is cancelled from the received signal prior to the equalizing with respect to others of the transmitting antennas.

63. The base station of claim 61 utilizing parallel interference cancellation, such that the equalizing the received signal with respect to all of the transmitting antennas is performed prior to canceling a contribution of any of the transmitting antennas from the received signal.

64. The base station of claim 61 further comprising a SIC/PIC control unit for selectively using either successive interference cancellation (SIC) or parallel interference cancellation (PIC), for SIC the equalizing the received signal with respect to one of the transmitting antennas and that one transmitting antennas contribution is cancelled from the received signal prior to the equalizing with respect to others of the transmitting antennas, and for PIC the equalizing the received signal with respect to all of the transmitting antennas is performed prior to canceling a contribution of any of the transmitting antennas from the received signal.

65. The base station of claim 61 further comprising a power measuring device for measuring a channel power of each transmitting antenna, means for comparing the measured channel power for each transmitting antenna and means based on the comparison, for determining whether SIC or PIC is to be selected.

66. The base station of claim 65 wherein if the measured channel power for each transmitting antenna is within a threshold, selecting PIC and if the measured channel power for each transmitting antenna is not within the threshold, selecting SIC.

67. The base station of claim 66 wherein if SIC is selected, the equalizing with respect to the channel of the transmitting antenna having a highest power level is performed prior to the other transmitting antennas.

68. The base station of claim 61 wherein the at least one communication includes a plurality of codes and the equalizing is performed collectively on all the codes.

69. The base station of claim 61 wherein the at least one communication includes a plurality of codes and the equalizing is performed sequentially on each code individually.

70. The base station of claim 61 wherein the at least one communication includes a plurality of codes and the plurality of codes are grouped into code groups, at least one code group having more than one code and the equalizing is performed sequentially on each code individually.

71. The base station of claim 61 wherein the produced symbols are spread symbols.

72. The base station of claim 71 further comprising at least one despreader for despreading the spread symbols.

73. The base station of claim 72 wherein the despread symbols with respect to the transmitting antenna having the largest receiver signal to interference/noise level is selected over the despread symbols of others of the transmitting antennas.

74. The base station of claim 72 wherein the despread symbols for all the transmitting antenna are combined.

75. The base station of claim 74 wherein the combining is performed by maximum ratio combining.

76. An integrated circuit for use in a processing a received signal from a plurality of transmitting sources, the integrated circuit comprising:

an input configured to receive the received signal;

a first matched filter for matched filtering the received signal with respect to a first group of codes, the received signal including a plurality of codes and the codes are grouped into a plurality of groups including the first group;

a first joint channel equalizer for equalizing the first group of signals, the joint channel equalizer processing a contribution from each transmitting source separately and canceling the contribution of at least one transmitting source from the other transmitting source;

a first despreader for despreading an output of the first joint channel equalizer;

a first soft to hard decision device for converting an output of the first despreader into hard symbols;

a first spread sequence reconstruction device for converting the hard symbols into a spread sequence;

an first interference construction device for producing a contribution of the spread sequence to the received signal; and

a first subtractor for subtracting the contribution from the received vector for use in processing a subsequenct group of the plurality of groups.

77. The integrated circuit of claim 76 wherein the first joint channel equalizer comprises a block equalizer.

78. The integrated circuit of claim 77 wherein the block equalizer comprises a minimum mean square error block linear equalization.

79. The integrated circuit of claim 77 wherein the block equalizer comprises a zero forcing block linear equalizer.

80. The integrated circuit of claim 76 wherein the first joint channel equalizer comprises an adaptive equalizer.

81. The integrated circuit of claim 77 wherein the adaptive equalizer comprises a normalized least mean squares equalizer.

82. The integrated circuit of claim 77 wherein the adaptive equalizer comprises a recursive least squares equalizer.

83. The integrated circuit of claim 76 wherein the subsequent group is processed by a second matched filter, a second joint channel equalizer, a second despreader, a second soft to hard decision device, a second spread sequence reconstruction device, a second interference construction device and a second subtractor for processing a next group of the plurality of groups.