Cancellation of burst noise in a communication system with application to S-CDMA

• US 7,643,538 B2
• Filed: 08/12/2008
• Issued: 01/05/2010
• Est. Priority Date: 08/31/1999
• Status: Expired due to Fees

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Yousef, Nabil R., Kolze, Thomas J., Currivan, Bruce J., Ungerboeck, Gottfried
• Primary Examiner(s): VO, DON NGUYEN
• Application Number:
  US12/190,505
• Publication Number:
  US 20080298437A1
• Time in Patent Office: 511 Days
• Field of Search: 375/141, 375/144, 375/145, 375/148, 375/149, 375/261, 370/320, 370/335, 370/342, 370/441
• US Class Current: 375/144
• CPC Class Codes: H04B 1/71 the interference being narrowband interference
• CPC Class Codes: H04B 1/7107 Subtractive interference cancellation
• CPC Class Codes: H04B 7/216 Code division or spread-spectrum multiple access [CDMA, SSMA]
• CPC Class Codes: H04J 13/0003 Code application, i.e. aspects relating to how codes are applied to form multiplexed channels
• CPC Class Codes: H04J 13/16 Code allocation
• CPC Class Codes: H04L 2025/03375 Passband transmission
• CPC Class Codes: H04L 2025/03477 not time-recursive
• CPC Class Codes: H04L 25/03038 with a non-recursive structure H04L25/03031 takes precedence
• CPC Class Codes: H04L 25/03343 Arrangements at the transmitter end
• CPC Class Codes: H04L 25/49 using code conversion at the transmitter; using predistortion; using insertion of idle bits for obtaining a desired frequency spectrum; using three or more amplitude levels ; Baseband coding techniques specific to data transmission systems spectral shaping H04L25/03828
• CPC Class Codes: H04L 27/3405 Modifications of the signal space to increase the efficiency of transmission, e.g. reduction of the bit error rate, bandwidth, or average power

Abstract

A communication system performs burst noise cancellation. A transmitter produces and transmits a spread signal that comprises at least one known-value symbol spread by a plurality of non data-carrying orthogonal codes and data symbols spread by at least one data-carrying orthogonal code. The transmitter transmits the spread signal across a communication link that introduces burst noise. A burst noise detector determines burst noise affected chips of the orthogonal codes. A weight computation functional block calculates a plurality of complex-valued combining weights based upon the burst noise affected chips. A vector de-spreader and a linear combiner operate in combination to use the plurality of non data-carrying orthogonal codes, the at least one data-carrying orthogonal code, and the plurality of complex-valued combining weights to de-spread the received spread signal to produce the data symbols with the burst noise substantially removed.

Claims

1. An apparatus, comprising:

a linear combiner that identifies an adapted rotated code based on burst noise affected chips within a chip sequence code of a spread signal; and

a vector despreader that uses the adapted rotated code to despread a spread signal to produce a plurality of data symbols that is substantially free of burst noise.

2. The apparatus of claim 1, wherein the linear combiner:

scales a plurality of non-data-carrying codes using a plurality of adaptive weights, that corresponds to the burst noise affected chips within the chip sequence code of a spread signal, thereby generating a plurality of scaled non-data-carrying codes; and

combines a data-carrying code with the plurality of scaled non-data-carrying codes thereby generating the adapted rotated code.

3. The apparatus of claim 2, further comprising:

a look up table (LUT) that stores the plurality of adaptive weights; and

wherein;

the linear combiner retrieves the plurality of adaptive weights from the LUT.

4. The apparatus of claim 3, wherein:

the plurality of adaptive weights is a pre-computed plurality of adaptive weights; and

the pre-computed plurality of adaptive weights is one set of a plurality of sets of pre-computed adaptive weights.

5. The apparatus of claim 2, further comprising:

a burst noise detector that processes the spread signal to identify the burst noise affected chips within the chip sequence code of the spread signal; and

a weight computation module that determines the plurality of adaptive weights based on the burst noise affected chips.

6. The apparatus of claim 2, wherein:

the plurality of adaptive weights is a plurality of complex-valued weights.

7. The apparatus of claim 2, wherein:

the linear combiner scales the data-carrying code using at least one adaptive weight of the plurality of adaptive weights before the data-carrying code is combined with the plurality of scaled non-data-carrying codes.

8. The apparatus of claim 2, wherein:

the plurality of non-data-carrying codes is modulated using numerically zero-valued symbols.

9. The apparatus of claim 1, wherein:

the apparatus includes a transmitter and a receiver, that includes the linear combiner and the vector despreader, to support bi-directional communication via a communication channel to which the apparatus couples;

the receiver receives the spread signal from the communication channel; and

the transmitter employs at least one additional code to spread at least one additional plurality of data symbols thereby generating at least one additional spread signal that is transmitted via the communication channel.

10. The apparatus of claim 1, wherein:

the apparatus is a wireless communication device.

11. The apparatus of claim 1, wherein:

the spread signal is a code-division multiple access (CDMA) signal or a synchronous code-division multiple access (S-CDMA) signal.

12. The apparatus of claim 1, wherein:

the plurality of data symbols is modulated according to at least one of Binary Phase Shift Keying (BPSK), Quadrature Phase Shift Keying (QPSK) or Quadrature Amplitude Modulation (QAM), 8 Phase Shift Keying (8-PSK), 16 QAM, 32 QAM, 64 QAM, 128 QAM, 256 QAM, 516 QAM, and 1024 QAM.

13. An apparatus, comprising:

a transmitter module that employs a first code to spread a first plurality of symbols thereby generating a first spread signal that is transmitted via a communication channel; and

a receiver module, that includes a linear combiner and a vector despreader, that receives a second spread signal from the communication channel; and

wherein;

the linear combiner;

scales a plurality of non-data-carrying codes using a plurality of adaptive weights, that corresponds to burst noise affected chips within a chip sequence code of the second spread signal, thereby generating a plurality of scaled non-data-carrying codes; and

combines a data-carrying code with the plurality of scaled non-data-carrying codes thereby generating an adapted rotated code; and

the vector despreader uses the adapted rotated code to despread the second spread signal to produce a second plurality of data symbols that is substantially free of burst noise.

14. The apparatus of claim 13, wherein the receiver modules includes:

a burst noise detector that processes the second spread signal to identify the burst noise affected chips within the chip sequence code of the second spread signal; and

a weight computation module that determines the plurality of adaptive weights based on the burst noise affected chips.

15. The apparatus of claim 13, wherein:

the plurality of adaptive weights is a plurality of complex-valued weights.

16. The apparatus of claim 13, further comprising:

a look up table (LUT) that stores the plurality of adaptive weights; and

wherein;

the linear combiner retrieves the plurality of adaptive weights from the LUT.

17. The apparatus of claim 16, wherein:

the plurality of adaptive weights is a pre-computed plurality of adaptive weights; and

the pre-computed plurality of adaptive weights is one set of a plurality of sets of pre-computed adaptive weights.

18. The apparatus of claim 13, wherein:

the linear combiner scales the data-carrying code using at least one adaptive weight of the plurality of adaptive weights before the data-carrying code is combined with the plurality of scaled non-data-carrying codes.

19. The apparatus of claim 13, wherein:

the plurality of non-data-carrying codes is modulated using numerically zero-valued symbols.

20. The apparatus of claim 13, wherein:

the apparatus is a wireless communication device.

21. The apparatus of claim 13, wherein:

at least one of the first spread signal and the second spread signal is a code-division multiple access (CDMA) signal or a synchronous code-division multiple access (S-CDMA) signal.

22. The apparatus of claim 13, wherein:

the first plurality of data symbols and the second plurality of data symbols is modulated according to at least one of Binary Phase Shift Keying (BPSK), Quadrature Phase Shift Keying (QPSK) or Quadrature Amplitude Modulation (QAM), 8 Phase Shift Keying (8-PSK), 16 QAM, 32 QAM, 64 QAM, 128 QAM, 256 QAM, 516 QAM, and 1024 QAM.

23. A method, comprising:

receiving a spread signal, that has incurred burst noise, from a communication channel;

within a linear combiner, identifying an adapted rotated code based on burst noise affected chips within a chip sequence code of the spread signal; and

within a vector despreader, employing the adapted rotated code to despread a spread signal to produce a plurality of data symbols that is substantially free of burst noise.

24. The method of claim 23, further comprising:

processing the spread signal to identify the burst noise affected chips within the chip sequence code of the second spread signal;

determining a plurality of adaptive weights based on the burst noise affected chips;

scaling a plurality of non-data-carrying codes using the plurality of adaptive weights thereby generating a plurality of scaled non-data-carrying codes; and

combining a data-carrying code with the plurality of scaled non-data-carrying codes thereby generating the adapted rotated code.

25. The method of claim 24, wherein:

the plurality of adaptive weights is a plurality of complex-valued weights.

26. The method of claim 24, further comprising:

scaling the data-carrying code using at least one adaptive weight of the plurality of adaptive weights before the data-carrying code is combined with the plurality of scaled non-data-carrying codes.

27. The method of claim 24, further comprising:

retrieving the plurality of adaptive weights from a look up table (LUT).

28. The method of claim 27, wherein:

the plurality of adaptive weights is a pre-computed plurality of adaptive weights; and

the pre-computed plurality of adaptive weights is one set of a plurality of sets of pre-computed adaptive weights.

29. The method of claim 24, wherein:

the plurality of non-data-carrying codes is modulated using numerically zero-valued symbols.

30. The method of claim 23, wherein:

the spread signal is a code-division multiple access (CDMA) signal or a synchronous code-division multiple access (S-CDMA) signal.

31. The method of claim 23, wherein:

the plurality of data symbols is modulated according to at least one of Binary Phase Shift Keying (BPSK), Quadrature Phase Shift Keying (QPSK) or Quadrature Amplitude Modulation (QAM), 8 Phase Shift Keying (8-PSK), 16 QAM, 32 QAM, 64 QAM, 128 QAM, 256 QAM, 516 QAM, and 1024 QAM.

32. An apparatus, comprising:

a vector despreader that employs a plurality of codes to despread a spread signal, that has incurred burst noise, thereby generating a plurality of despread signals; and

a linear combiner that;

scales a subset of the plurality of despread signals using a plurality of adaptive weights thereby generating a plurality of scaled despread signals; and

adds a selected one of the plurality of despread signals, which is not included in the subset of the plurality of despread signals, to the plurality of scaled despread signals thereby generating a modified despread signal from which a plurality of data symbols that is substantially free of burst noise is produced.

33. The apparatus of claim 32, wherein the linear combiner:

scales at least one additional subset of the plurality of despread signals using at least one additional plurality of adaptive weights thereby generating at least one additional plurality of scaled despread signals; and

adds at least one additional selected one of the plurality of despread signals, which is not included in the subset of the plurality of despread signals or the at least one additional subset of the plurality of despread signals, to the plurality of scaled despread signals and to the at least one additional plurality of scaled despread signals thereby generating the modified despread signal.

34. The apparatus of claim 32, further comprising:

a slicer that makes a hard decision corresponding to at least one of the plurality of data symbols; and

wherein;

the linear combiner employs the hard decision as a known symbol within at least one of the plurality of despread signals when generating at least one additional modified despread signal from which at least one additional plurality of data symbols that is substantially free of burst noise is produced.

35. The apparatus of claim 34, wherein:

the known symbol within the at least one of the plurality of despread signals is a non-zero or known non-data carrying symbol.

36. The apparatus of claim 34, wherein:

the at least one additional plurality of data symbols includes less burst noise than the plurality of data symbols.

37. The apparatus of claim 34, wherein:

the plurality of data symbols is generated in a first iteration of iterative processing; and

the at least one additional plurality of data symbols is generated in a second iteration of the iterative processing.

38. The apparatus of claim 32, wherein:

the subset of the plurality of despread signals corresponds to a plurality of non-data-carrying codes of the plurality of codes; and

the selected one of the plurality of despread signals corresponds to a data-carrying code.

39. The apparatus of claim 38, wherein:

each despread signal in a subset of the plurality of despread signals includes a corresponding known sequence of symbols.

40. The apparatus of claim 32, further comprising:

a slicer that processes the modified despread signal thereby generating the plurality of data symbols.

41. The apparatus of claim 32, further comprising:

a burst noise detector that processes the spread signal to identify burst noise affected chips within the chip sequence code of the spread signal; and

a weight computation module that determines the plurality of adaptive weights based on the burst noise affected chips.

42. The apparatus of claim 32, wherein:

at least one of the plurality of despread signals includes a known sequence of symbols.

43. The apparatus of claim 42, wherein:

the known sequence of symbols includes numerically zero-valued symbols.

44. The apparatus of claim 32, further comprising:

a look up table (LUT) that stores the plurality of adaptive weights; and

wherein;

the linear combiner retrieves the plurality of adaptive weights from the LUT.

45. The apparatus of claim 44, wherein:

the plurality of adaptive weights is a pre-computed plurality of adaptive weights; and

the pre-computed plurality of adaptive weights is one set of a plurality of sets of pre-computed adaptive weights.

46. The apparatus of claim 32, wherein:

the apparatus is a wireless communication device.

47. The apparatus of claim 32, wherein:

the spread signal is a code-division multiple access (CDMA) signal or a synchronous code-division multiple access (S-CDMA) signal.

48. The apparatus of claim 32, wherein:

the plurality of data symbols is modulated according to at least one of Binary Phase Shift Keying (BPSK), Quadrature Phase Shift Keying (QPSK) or Quadrature Amplitude Modulation (QAM), 8 Phase Shift Keying (8-PSK), 16 QAM, 32 QAM, 64 QAM, 128 QAM, 256 QAM, 516 QAM, and 1024 QAM.

49. An apparatus, comprising:

a linear combiner that identifies a first adapted rotated code and a second adapted rotated code based on burst noise affected chips within a chip sequence code of a spread signal; and

a vector despreader that;

uses the first adapted rotated code, that effectuates a first notch at a first location within the burst noise affected chips, to despread a spread signal to produce a first plurality of data symbols having first burst noise; and

uses the second adapted rotated code, that effectuates a second notch at a second location within the burst noise affected chips, to despread the spread signal to produce a second plurality of data symbols having second burst noise; and

wherein;

when the first burst noise is less than the second burst noise, the apparatus outputs the first plurality of data symbols; and

when the first burst noise is greater than or equal to the second burst noise, the apparatus outputs the second plurality of data symbols.

50. The apparatus of claim 49, wherein:

the vector despreader superimposes the first notch at the first location and the second notch at the second location to despread the spread signal to produce a third plurality of data symbols having third burst noise.

51. The apparatus of claim 49, wherein:

the first notch at the first location is a first pre-computed notch; and

the second notch at the second location is a second pre-computed notch.

52. The apparatus of claim 49, wherein:

the second notch at the second location is a dithered version of the first notch at the first location.

53. The apparatus of claim 49, wherein:

the first notch at the first location has a first depth; and

the second notch at the first location has a second depth.

54. The apparatus of claim 49, wherein the linear combiner:

scales a plurality of non-data-carrying codes using a plurality of adaptive weights, that corresponds to the burst noise affected chips within the chip sequence code of a spread signal, thereby generating a plurality of scaled non-data-carrying codes; and

combines a data-carrying code with the plurality of scaled non-data-carrying codes thereby generating at least one of the first adapted rotated code and the second adapted rotated code.

55. The apparatus of claim 54, further comprising:

a look up table (LUT) that stores the plurality of adaptive weights; and

wherein;

the linear combiner retrieves the plurality of adaptive weights from the LUT.

56. The apparatus of claim 55, wherein:

the plurality of adaptive weights is a pre-computed plurality of adaptive weights; and

the pre-computed plurality of adaptive weights is one set of a plurality of sets of pre-computed adaptive weights.

57. The apparatus of claim 49, wherein:

the second adapted rotated code is identified based on at least one characteristic of the first plurality of data symbols having first burst noise.

58. The apparatus of claim 57, wherein:

the at least one characteristic of the first plurality of data symbols having first burst noise is a signal to noise ratio (SNR).

59. The apparatus of claim 49, wherein:

the apparatus is a wireless communication device.

60. The apparatus of claim 49, wherein:

the spread signal is a code-division multiple access (CDMA) signal or a synchronous code-division multiple access (S-CDMA) signal.

61. The apparatus of claim 49, wherein:

the plurality of data symbols is modulated according to at least one of Binary Phase Shift Keying (BPSK), Quadrature Phase Shift Keying (QPSK) or Quadrature Amplitude Modulation (QAM), 8 Phase Shift Keying (8-PSK), 16 QAM, 32 QAM, 64 QAM, 128 QAM, 256 QAM, 516 QAM, and 1024 QAM.