Systems and methods for serial cancellation

• US 8,090,006 B2
• Filed: 10/29/2010
• Issued: 01/03/2012
• Est. Priority Date: 09/23/2002
• Status: Expired due to Fees

• Current Assignee: III Holdings 1, LLC (Intellectual Ventures LLC)
• Original Assignee: Rambus Inc.
• Inventors: Narayan, Anand P., Olson, Eric S.
• Primary Examiner(s): Tran, Khai
• Application Number:
  US12/916,467
• Publication Number:
  US 20110064172A1
• Time in Patent Office: 431 Days
• Field of Search: 375/148, 375/130, 375/267, 375/342, 375/347, 375/348, 370/209, 370/335, 370/337, 370/342, 455/132, 455/137, 455/138
• US Class Current: 375/148
• 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 sub channel 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 processing engine, comprising:

a first input configured for receiving an input signal;

a plurality of outputs, wherein each output is configured for providing a substantially interference canceled signal;

at least one second input configured for receiving one of the substantially interference canceled signals from one of the outputs; and

an interference selector configured for receiving the input signal and the substantially interference canceled signal and for selecting an interfering signal from each of the input signal and said at least one substantially interference canceled signal;

wherein the processing engine is configured for substantially canceling an interfering signal from the input signal and from at least one of the substantially interference canceled signals.

2. The processing engine of claim 1, wherein the processing engine is configurable with at least one of a handset receiver and a base station receiver.

3. The processing engine of claim 1, wherein the interference selector is configured for selecting interfering signal paths based on pre-determined criteria.

4. The processing engine of claim 1, further comprising a plurality of matrix generators, wherein each of the plurality of matrix generators is communicatively coupled to the interference selector and configured for generating a matrix based on a selected interfering signal provided by the interference selector.

5. The processing engine of claim 4, wherein each of the plurality of matrix generators is configured to generate a matrix constructed from at least one vector to produce a plurality of matrices, and wherein each of the at least one vector comprises elements from the selected interfering signal.

6. The processing engine of claim 4, wherein the processing engine is further configured for substantially canceling a plurality of interfering signals from the input signal or from at least one of the substantially interference canceled signals wherein each matrix generator is configured for generating a matrix based on a selected plurality of interfering signals.

7. The processing engine of claim 6, wherein the plurality of matrix generators are adapted to construct the plurality of matrices from at least one vector, and wherein at least one of the at least one vector is a composite vector comprising elements from at least two of the selected plurality of interfering signals.

8. The processing engine of claim 1, further comprising a processor configured for generating a plurality of cancellation operators, wherein each cancellation operator is used to substantially cancel one of the interfering signals to produce at least one substantially interference canceled signal.

9. The processing engine of claim 8, further comprising a plurality of applicators, wherein each applicator is communicatively coupled to the processor and configured for applying one of the cancellation operators to either the input signal or said at least one substantially interference canceled signal.

10. The processing engine of claim 9, wherein at least one of the applicators is configured for applying one of the cancellation operators according to the form:

y′

=y−

S(S^TS)<sup>−

1</sup>S^Ty,

where y′

is an output canceled signal, y is a received signal, S is an interference matrix and S^T is a transpose of S.

11. The processing engine of claim 8, wherein each cancellation operator is a projection operator configured for projecting either the input signal or said at least one substantially interference canceled signal onto a subspace that is substantially orthogonal to one of the interfering signals.

12. The processing engine of claim 11, wherein each projection operator comprises the form:

P_s^⊥

=I−

S(S^TS)<sup>−

1</sup>S^T,

wherein P_s^⊥

is the projection operator, I is an identity matrix, S is an interference matrix and S^T is a transpose of the interference matrix.

13. The processing engine of claim 8, wherein at least one of the cancellation operators is configured to substantially cancel one of the interfering signals via an approximated projection operation comprising the form:

14. The processing engine of claim 1, wherein the input signal comprises a plurality of digital signals selected from a group consisting of a Code Division Multiple Access signal, a Wideband Code Division Multiple Access signal, a broadband Code Division Multiple Access signal, a Global Positioning Signal, and a Universal Mobile Telephone Service signal.

15. The processing engine of claim 1, further comprising at least one delay element, wherein each of the at least one delay element is used for compensating delay introduced by the processing engine.

16. The processing engine of claim 1, further comprising at least one advance element, wherein each of the at least one advance element is adapted to advance an on-time PN code by a duration substantially equal to delay introduced by the processing engine.

17. A system, comprising:

means for receiving an input signal;

means for substantially canceling a signal interfering with the input signal to generate a first substantially interference canceled signal;

means for receiving the first substantially interference canceled signal, wherein the means for substantially canceling a signal interfering with the input signal further comprises means for substantially canceling a signal interfering with the first substantially interference canceled signal to generate a second substantially interference canceled signal, wherein the means for substantially canceling the signal interfering with the input signal comprises means for performing a cancellation operation on the input signal according to the form;

y′

=y−

S(S^TS)<sup>−

1</sup>S^Ty,

where y′

is the first substantially interference canceled signal, y is a received signal, S is an interference matrix and S^T is a transpose of S.

18. The system of claim 17, further comprising means for generating a cancellation operator in response to receiving the input signal.

19. The system of claim 18, wherein the means for generating the cancellation operator comprises means for generating a projection operator according to the form:

P_s^⊥

=I−

S(S^TS)<sup>−

1</sup>S^T

wherein P_s^⊥

is the projection operator, I is an identity matrix, S is an interference matrix and S^T is a transpose of the interference matrix.

20. The system of claim 17, further comprising means for generating a cancellation operator in response to receiving the first substantially interference canceled signal.

21. The system of claim 20, wherein the means for generating the cancellation operator comprises means for generating a projection operator according to the form:

P_s^⊥

=I−

S(S^TS)<sup>−

1</sup>S^T

wherein P_s^⊥

is the projection operator, I is an identity matrix, S is an interference matrix and S^T is a transpose of the interference matrix.

22. The system of claim 17, wherein the means for substantially canceling the signal interfering with the first substantially interference canceled signal comprises means for applying a cancellation operator to the input signal according to the form:

y″

=y′

−

S(S^TS)<sup>−

1</sup>S^Ty,

where y″

is the second substantially interference canceled signal, y′

is the first substantially interference canceled signal, S is an interference matrix and S^T is a transpose of S.

23. The system of claim 17, wherein the means for substantially canceling the signal interfering with the first substantially interference canceled signal comprises means for performing a cancellation operation on the first substantially interference canceled signal according to the form:

y″

=y′

−

S(S^TS)<sup>−

1</sup>S^Ty,

where y″

is the second substantially interference canceled signal, y′

is the first substantially interference canceled signal, S is an interference matrix and S^T is a transpose of S.

24. The system of claim 17, wherein the means for substantially canceling the signal interfering with the first substantially interference canceled signal comprises means for performing a cancellation operation on the first substantially interference canceled signal resulting in an approximated projection operation comprising the form:

25. The system of claim 17, further comprising means for transferring the first substantially interference canceled signal and the second substantially interference canceled signal to a receiver.

26. The system of claim 25, wherein the receiver is configurable with a handset or a base station.

27. The system of claim 17, wherein the input signal comprises a plurality of digital signals selected from a group consisting of a Code Division Multiple Access signal, a Wideband Code Division Multiple Access signal, a broadband Code Division Multiple Access signal, a Global Positioning Signal, and a, Universal Mobile Telephone Service signal.

28. The system of claim 17, further comprising one or more delay elements, wherein each of the one or more delay elements is configured for compensating delay introduced by the processing engine.

29. The system of claim 17, further comprising one or more advance elements, wherein each of the one or more advance elements is configured for advancing an on-time PN code by a duration substantially equal to delay introduced by the processing engine.

30. A handset comprising a processing engine, the processing engine comprising:

a first interference canceller configured for receiving an input signal and configured for providing a substantially interference canceled signal;

at least one second interference canceller configured for receiving the substantially interference canceled signal; and

an interference selector configured for receiving the input signal and the substantially interference canceled signal and for selecting an interfering signal from each of the input signal and said at least one substantially interference canceled signal,

wherein the second interference canceller is configured for substantially canceling an interfering signal from the at least one substantially interference canceled signal.

31. The handset recited in claim 30, wherein the interference selector is configured for selecting interfering signal paths based on pre-determined criteria.

32. The handset of claim 31, further comprising a plurality of matrix generators, wherein each of the plurality of matrix generators is communicatively coupled to the interference selector and configured for generating a matrix based on a selected interfering signal provided by the interference selector.

33. The handset of claim 32, wherein each of the plurality of matrix generators is configured to generate a matrix constructed from at least one vector to produce a plurality of matrices, and wherein each of the at least one vector comprises elements from the selected interfering signal.

34. The handset of claim 32, wherein the processing engine is further configured for substantially canceling a plurality of interfering signals from the input signal or from at least one of the substantially interference canceled signals wherein each matrix generator is configured for generating a matrix based on a selected plurality of interfering signals.

35. The handset of claim 34, wherein the plurality of matrix generators are adapted to construct the plurality of matrices from at least one vector, and wherein at least one of the at least one vector is a composite vector comprising elements from at least two of the selected plurality of interfering signals.

36. The handset of claim 30, further comprising a processor configured for generating a plurality of cancellation operators, wherein each cancellation operator is used to substantially cancel one of the interfering signals to produce at least one substantially interference canceled signal.

37. The handset of claim 36, further comprising a plurality of applicators, wherein each applicator is communicatively coupled to the processor and configured for applying one of the cancellation operators to either the input signal or said at least one substantially interference canceled signal.

38. The handset of claim 37, wherein at least one of the applicators is configured for applying one of the cancellation operators according to the form:

y′

=y−

S(S^TS)<sup>−

1</sup>S^Ty,

where y′

is an output canceled signal, y is a received signal, S is an interference matrix and S^T is a transpose of S.

39. The handset of claim 36, wherein each cancellation operator is a projection operator configured for projecting either the input signal or said at least one substantially interference canceled signal onto a subspace that is substantially orthogonal to one of the interfering signals.

40. The handset of claim 39, wherein each projection operator comprises the form:

P_s^⊥

=I−

S(S^TS)<sup>−

1</sup>S^T,

wherein P_s^⊥

is the projection operator, I is an identity matrix, S is an interference matrix and S^T is a transpose of the interference matrix.

41. The handset of claim 36, wherein at least one of the cancellation operators is configured to substantially cancel one of the interfering signals via an approximated projection operation comprising the form:

42. The handset of claim 30, wherein the input signal comprises a plurality of digital signals selected from a group consisting of a Code Division Multiple Access signal, a Wideband Code Division Multiple Access signal, a broadband Code Division Multiple Access signal, a Global Positioning Signal, and a Universal Mobile Telephone Service signal.

43. The processing engine of claim 30, further comprising at least one delay element, wherein each of the at least one delay element is used for compensating delay introduced by the processing engine.

44. The processing engine of claim 30, further comprising at least one advance element, wherein each of the at least one advance element is adapted to advance an on-time PN code by a duration substantially equal to delay introduced by the processing engine.

45. A handset, comprising:

an antenna configured for receiving a radio signal, wherein the radio signal comprises at least one signal of interest and one or more interfering signals;

an analog to digital converter configured for converting the radio signal to a digital signal;

an input signal coupler configured for receiving the digital signal to produce an input signal;

a first interference canceller configured for substantially canceling a signal interfering with the input signal to generate a first substantially interference canceled signal;

means for generating a cancellation operator in response to receiving the first substantially interference canceled signal; and

a second interference canceller configured for receiving the first substantially interference canceled signal, wherein the second interference canceller is further configured for substantially canceling a signal interfering with the first substantially interference canceled signal to generate a second substantially interference canceled signal.

46. The handset of claim 45, further comprising means for generating a cancellation operator in response to receiving the input signal.

47. The handset of claim 46, wherein the means for generating the cancellation operator comprises means for generating a projection operator according to the form:

P_s^⊥

=I−

S(S^TS)<sup>−

1</sup>S^T,

wherein P_s^⊥

is the projection operator, I is an identity matrix, S is an interference matrix and S^T is a transpose of the interference matrix.

48. The handset of claim 45, wherein the first interference canceller comprises means for performing a cancellation operation on the input signal according to the form:

y′

=y−

S(S^TS)<sup>−

1</sup>S^Ty,

where y′

is the first substantially interference canceled signal, y is a received signal, S is an interference matrix and S^T is a transpose of S.

49. The handset of claim 45, wherein the first interference canceller comprises means for performing a cancellation operation on the input signal resulting in an approximated projection comprising the form:

50. The handset of claim 45, wherein the means for generating the cancellation operator comprises means for generating a projection operator according to the form:

P_s^⊥

=I−

S(S^TS)<sup>−

1</sup>S^T,

wherein P_s^⊥

is the projection operator, I is an identity matrix, S is an interference matrix and S^T is a transpose of the interference matrix.

51. The handset of claim 45, wherein the second interference canceller comprises means for applying a cancellation operator to the input signal according to the form:

y″

=y′

−

S(S^TS)<sup>−

1</sup>S^Ty,

where y″

is the second substantially interference canceled signal, y′

is the first substantially interference canceled signal, S is an interference matrix and S^T is a transpose of S.

52. The handset of claim 45, wherein the second interference canceller comprises means for performing a cancellation operation on the first substantially interference canceled signal according to the form:

y″

=y′

−

S(S^TS)<sup>−

1</sup>S^Ty,

where y″

is the second substantially interference canceled signal, y′

is the first substantially interference canceled signal, S is an interference matrix and S^T is a transpose of S.

53. The handset of claim 45, wherein the second interference canceller comprises means for performing a cancellation operation on the first substantially interference canceled signal resulting in an approximated projection operation comprising the form:

54. The handset of claim 45, further comprising means for transferring the first substantially interference canceled signal and the second substantially interference canceled signal to a receiver.

55. The handset of claim 54, wherein the receiver is configurable with a handset or a base station.

56. The handset of claim 45, wherein the input signal comprises a plurality of digital signals selected from a group consisting of a Code Division Multiple Access signal, a Wideband Code Division Multiple Access signal, a broadband Code Division Multiple Access signal, a Global Positioning Signal, and a Universal Mobile Telephone Service signal.

57. The system of claim 45, further comprising one or more delay elements, wherein each of the one or more delay elements is configured for compensating delay introduced by the processing engine.

58. The system of claim 45, further comprising one or more advance elements, wherein each of the one or more advance elements is configured for advancing an on-time PN code by a duration substantially equal to delay introduced by the processing engine.