Multi-mode orthogonal frequency division multiplexing receiver for highly-spectrally-efficient communications

1. A receiver comprising:

circuitry comprising a decoding circuit and being operable in at least two modes, wherein:

while said circuitry operates in a first of said modes, said decoding circuit processes OFDM symbols received on a first number of data-carrying subcarriers to recover a number of mapped symbols per OFDM symbol that is greater than said first number; and

while said circuitry operates in a second of said modes, said decoding circuit processes OFDM symbols received on a second number of data-carrying subcarriers to recover a number of mapped symbols per OFDM symbol that is equal to or less than said second number;

said circuitry receives OFDM symbols via a channel having significant nonlinearity such that:

while said circuitry operates in said first of said modes, said nonlinearity degrades a performance metric by less than 1 dB, relative to a perfectly linear channel; and

while said circuitry operates in said second of said modes, said nonlinearity degrades said performance metric by 1 dB or more, relative to a perfectly linear channel.

2. The receiver of claim 1 , wherein said mapped symbols are N-QAM symbols, N being an integer.

3. The receiver of claim 1 , wherein said decoding circuit is a sequence estimation circuit.

4. The receiver of claim 3 , wherein said sequence estimation circuit is based on a maximum-likelihood sequence estimation circuit.

5. The receiver of claim 3 , wherein:

while said circuitry operates in said first of said modes, said sequence estimation circuit generates candidate vectors and processes said candidate vectors using an inter-symbol correlation and/or inter-subcarrier interference (ISCI) model to generate reconstructed physical subcarrier values.

6. The receiver of claim 5 , wherein said ISCI model incorporates a non-linear model.

7. The receiver of claim 3 , wherein:

while said circuitry operates in said first of said modes, said sequence estimation circuit generates metrics based on a difference between reconstructed physical subcarrier values and values received on said first number of data-carrying subcarriers, and selects a best candidate based on said metrics.

8. The receiver of claim 1 , wherein said circuitry comprises a modeling circuit, wherein:

while said circuitry operates in said first of said modes, a model output by said modeling circuit is based on cyclic filtering and/or decimation used in generation of said OFDM symbols.

9. The receiver of claim 1 , wherein said circuitry comprises a modeling circuit, wherein:

while said circuitry operates in said first of said modes, said modeling circuit is enabled and generates a model used by said decoding circuit; and

while said circuitry operates in said second of said modes, said modeling circuit is disabled.

10. The receiver of claim 1 , wherein said circuitry is configurable between said first and said second of said modes during operation based on one or more of: feedback, channel or other communication conditions, network controller, application and user input.

11. The receiver of claim 1 , wherein said first number is different than said second number.

12. A method performed by an electronic receiver that operates in at least two modes, said method comprising:

while said receiver operates in a first of said modes:

receiving OFDM symbols on a first number of data-carrying subcarriers; and

processing said OFDM symbols to recover a number of mapped symbols per OFDM symbol that is greater than said first number;

generating candidate vectors and processing said candidate vectors using a controlled ISCI model to generate reconstructed physical subcarrier values; and

while said receiver operates in a second of said modes,

receiving OFDM symbols on a second number of data-carrying subcarriers; and

processing said OFDM symbols to recover a number of mapped symbols per OFDM symbol that is equal to or less than said second number.

13. The method of claim 12 , wherein said mapped symbols are N-QAM symbols, N being an integer.

14. The method of claim 12 , wherein said processing comprises performing a sequence estimation.

15. The method of claim 14 , wherein said sequence estimation is based on maximum-likelihood sequence estimation.

16. The method of claim 12 , wherein said ISCI model incorporates a non-linear model.

17. The method of claim 12 , comprising:

while said receiver operates in a first of said modes, generating metrics based on a difference between said reconstructed physical subcarrier values and values received on said first number of data-carrying subcarriers and selecting a best candidate based on said metrics.

18. The method of claim 12 comprising:

while said receiver operates in a first of said modes, generating a model that is based on cyclic filtering and/or decimation used in generation of said OFDM symbols.

19. The method of claim 12 comprising:

while said receiver operates in said first of said modes and a modeling circuit is enabled:

generating, via a model generated by said modeling circuit, reconstructed physical subcarrier values; and

while said receiver operates in said second of said modes, said modeling circuit is disabled.

20. The method of claim 12 , comprising configuring said receiver between said first and said second of said modes during operation based on one or more of: feedback, channel or other communication conditions, network controller, application, and user input.

21. The method of claim 12 , wherein said second number is different than said first number.

22. A receiver comprising:

circuitry comprising a decoding circuit and being operable in at least two modes, wherein:

while said circuitry operates in a first of said modes, said decoding circuit processes OFDM symbols received on a first number of data-carrying subcarriers to recover a number of mapped symbols per OFDM symbol that is greater than said first number;

while said circuitry operates in a second of said modes, said decoding circuit processes OFDM symbols received on a second number of data-carrying subcarriers to recover a number of mapped symbols per OFDM symbol that is equal to or less than said second number;

said decoding circuit is a sequence estimation circuit;

while said circuitry operates in said first of said modes, said sequence estimation circuit generates candidate vectors and process said candidate vectors using an inter-symbol correlation and/or inter-subcarrier interference (ISCI) model to generate reconstructed physical subcarrier values; and

said ISCI model incorporates a non-linear model.

23. The receiver of claim 22 , wherein said circuitry receives OFDM symbols via a channel having significant nonlinearity such that:

while said circuitry operates in said first of said modes, said nonlinearity degrades a performance metric by less than 1 dB, relative to a perfectly linear channel; and

while said circuitry operates in said second of said modes, said nonlinearity degrades said performance metric by 1 dB or more, relative to a perfectly linear channel.

24. The receiver of claim 22 , wherein said mapped symbols are N-QAM symbols, N being an integer.

25. The receiver of claim 22 , wherein said sequence estimation circuit is based on a maximum-likelihood sequence estimation circuit.

26. The receiver of claim 22 , wherein:

while said circuitry operates in said first of said modes, said sequence estimation circuit generates metrics based on a difference between said reconstructed physical subcarrier values and values received on said first number of data-carrying subcarriers, and selects a best candidate based on said metrics.

27. The receiver of claim 22 , wherein said circuitry comprises a modeling circuit, wherein:

while said circuitry operates in said first of said modes, a model output by said modeling circuit is based on cyclic filtering and/or decimation used in generation of said OFDM symbols.

28. The receiver of claim 22 , wherein said circuitry comprises a modeling circuit, wherein:

while said circuitry operates in said first of said modes, said modeling circuit is enabled and generates a model used by said decoding circuit; and

while said circuitry operates in said second of said modes, said modeling circuit is disabled.

29. The receiver of claim 22 , wherein said circuitry is configurable between said first and said second of said modes during operation based on one or more of: feedback, channel or other communication conditions, network controller, application and user input.

30. The receiver of claim 22 , wherein said first number is different than said second number.

31. A receiver comprising:

circuitry comprising a decoding circuit and being operable in at least two modes, wherein:

while said circuitry operates in a first of said modes, said decoding circuit processes OFDM symbols received on a first number of data-carrying subcarriers to recover a number of mapped symbols per OFDM symbol that is greater than said first number;

while said circuitry operates in a second of said modes, said decoding circuit processes OFDM symbols received on a second number of data-carrying subcarriers to recover a number of mapped symbols per OFDM symbol that is equal to or less than said second number;

said decoding circuit is a sequence estimation circuit; and

while said circuitry operates in said first of said modes, said sequence estimation circuit generates metrics based on a difference between reconstructed physical subcarrier values and values received on said first number of data-carrying subcarriers, and selects a best candidate based on said metrics.

32. The receiver of claim 31 , wherein said circuitry receives OFDM symbols via a channel having significant nonlinearity such that:

while said circuitry operates in said first of said modes, said nonlinearity degrades a performance metric by less than 1 dB, relative to a perfectly linear channel; and

while said circuitry operates in said second of said modes, said nonlinearity degrades said performance metric by 1 dB or more, relative to a perfectly linear channel.

33. The receiver of claim 31 , wherein said mapped symbols are N-QAM symbols, N being an integer.

34. The receiver of claim 31 , wherein said sequence estimation circuit is based on a maximum-likelihood sequence estimation circuit.

35. The receiver of claim 31 , wherein:

while said circuitry operates in said first of said modes, said sequence estimation circuit generates candidate vectors and process said candidate vectors using an inter-symbol correlation and/or inter-subcarrier interference (IS CI) model to generate said reconstructed physical subcarrier values.

36. The receiver of claim 35 , wherein said ISCI model incorporates a non-linear model.

37. The receiver of claim 31 , wherein said circuitry comprises a modeling circuit, wherein:

while said circuitry operates in said first of said modes, a model output by said modeling circuit is based on cyclic filtering and/or decimation used in generation of said OFDM symbols.

38. The receiver of claim 31 , wherein said circuitry comprises a modeling circuit, wherein:

while said circuitry operates in said first of said modes, said modeling circuit is enabled and generates a model used by said decoding circuit; and

while said circuitry operates in said second of said modes, said modeling circuit is disabled.

39. The receiver of claim 31 , wherein said circuitry is configurable between said first and said second of said modes during operation based on one or more of: feedback, channel or other communication conditions, network controller, application and user input.

40. The receiver of claim 31 , wherein said first number is different than said second number.

41. A receiver comprising:

circuitry comprising a decoding circuit and being operable in at least two modes, wherein:

while said circuitry operates in a first of said modes, said decoding circuit processes OFDM symbols received on a first number of data-carrying subcarriers to recover a number of mapped symbols per OFDM symbol that is greater than said first number;

while said circuitry operates in a second of said modes, said decoding circuit processes OFDM symbols received on a second number of data-carrying subcarriers to recover a number of mapped symbols per OFDM symbol that is equal to or less than said second number;

said circuitry comprises a modeling circuit; and

while said circuitry operates in said first of said modes, a model output by said modeling circuit is based on cyclic filtering and/or decimation used in generation of said OFDM symbols.

42. The receiver of claim 41 , wherein said mapped symbols are N-QAM symbols, N being an integer.

43. The receiver of claim 41 , wherein said decoding circuit is a sequence estimation circuit.

44. The receiver of claim 43 , wherein said sequence estimation circuit is based on a maximum-likelihood sequence estimation circuit.

45. The receiver of claim 43 , wherein:

while said circuitry operates in said first of said modes, a sequence estimation circuit generates candidate vectors and process said candidate vectors using an inter-symbol correlation and/or inter-subcarrier interference (ISCI) model to generate reconstructed physical subcarrier values.

46. The receiver of claim 45 , wherein said ISCI model incorporates a non-linear model.

47. The receiver of claim 41 , wherein:

while said circuitry operates in said first of said modes, a sequence estimation circuit generates metrics based on a difference between reconstructed physical subcarrier values and values received on said first number of data-carrying subcarriers, and selects a best candidate based on said metrics.

48. The receiver of claim 41 , wherein said circuitry comprises a modeling circuit, wherein:

while said circuitry operates in said first of said modes, said modeling circuit is enabled and generates a model used by said decoding circuit; and

while said circuitry operates in said second of said modes, said modeling circuit is disabled.

49. The receiver of claim 41 , wherein said circuitry is configurable between said first and said second of said modes during operation based on one or more of: feedback, channel or other communication conditions, network controller, application and user input.

50. The receiver of claim 41 , wherein said first number is different than said second number.

51. A receiver comprising:

circuitry comprising a decoding circuit and being operable in at least two modes, wherein:

while said circuitry operates in a first of said modes, said decoding circuit processes OFDM symbols received on a first number of data-carrying subcarriers to recover a number of mapped symbols per OFDM symbol that is greater than said first number;

while said circuitry operates in a second of said modes, said decoding circuit processes OFDM symbols received on a second number of data-carrying subcarriers to recover a number of mapped symbols per OFDM symbol that is equal to or less than said second number;

said circuitry comprises a modeling circuit;

while said circuitry operates in a first of said modes, said modeling circuit is enabled and generates a model used by said decoding circuit; and

while said circuitry operates in a second of said modes, said modeling circuit is disabled.

52. The receiver of claim 51 , wherein said circuitry receives OFDM symbols via a channel having significant nonlinearity such that:

while said circuitry operates in said first of said modes, said nonlinearity degrades a performance metric by less than 1 dB, relative to a perfectly linear channel; and

while said circuitry operates in said second of said modes, said nonlinearity degrades said performance metric by 1 dB or more, relative to a perfectly linear channel.

53. The receiver of claim 51 , wherein said mapped symbols are N-QAM symbols, N being an integer.

54. The receiver of claim 51 , wherein said decoding circuit is a sequence estimation circuit.

55. The receiver of claim 54 , wherein said sequence estimation circuit is based on a maximum-likelihood sequence estimation circuit.

56. The receiver of claim 54 , wherein:

while said circuitry operates in said first of said modes, said sequence estimation circuit generates candidate vectors and process said candidate vectors using an inter-symbol correlation and/or inter-subcarrier interference (ISCI) model to generate reconstructed physical subcarrier values.

57. The receiver of claim 56 , wherein said ISCI model incorporates a non-linear model.

58. The receiver of claim 54 , wherein:

while said circuitry operates in said first of said modes, said sequence estimation circuit generates metrics based on a difference between reconstructed physical subcarrier values and values received on said first number of data-carrying subcarriers, and selects a best candidate based on said metrics.

59. The receiver of claim 51 , wherein said circuitry is configurable between said first and said second of said modes during operation based on one or more of: feedback, channel or other communication conditions, network controller, application and user input.

60. The receiver of claim 51 , wherein said first number is different than said second number.

61. A method performed by an electronic receiver that operates in at least two modes, said method comprising:

while said receiver operates in a first of said modes:

receiving OFDM symbols on a first number of data-carrying subcarriers; and

processing said OFDM symbols to recover a number of mapped symbols per OFDM symbol that is greater than said first number;

generating metrics based on a difference between reconstructed physical subcarrier values and values received on said first number of data-carrying subcarriers, and selecting a best candidate based on said metrics; and

while said receiver operates in a second of said modes,

receiving OFDM symbols on a second number of data-carrying subcarriers; and

processing said OFDM symbols to recover a number of mapped symbols per OFDM symbol that is equal to or less than said second number.

62. The method of claim 61 , wherein said mapped symbols are N-QAM symbols, N being an integer.

63. The method of claim 61 , wherein said processing comprises performing a sequence estimation.

64. The method of claim 63 , wherein said sequence estimation is based on maximum-likelihood sequence estimation.

65. The method of claim 61 comprising:

while said receiver operates in a first of said modes, generating a model that is based on cyclic filtering and/or decimation used in generation of said OFDM symbols.

66. The method of claim 61 comprising:

while said receiver operates in said first of said modes and a modeling circuit is enabled:

generating, via a model generated by said modeling circuit, reconstructed physical subcarrier values; and

while said receiver operates in said second of said modes, said modeling circuit is disabled.

67. The method of claim 61 , comprising configuring said receiver between said first and said second of said modes during operation based on one or more of: feedback, channel or other communication conditions, network controller, application, and user input.

68. The method of claim 61 , wherein said second number is different than said first number.

69. A method performed by an electronic receiver that operates in at least two modes, said method comprising:

while said receiver operates in a first of said modes:

receiving OFDM symbols on a first number of data-carrying subcarriers; and

processing said OFDM symbols to recover a number of mapped symbols per OFDM symbol that is greater than said first number;

generating a model that is based on cyclic filtering and/or decimation used in generation of said OFDM symbols; and

while said receiver operates in a second of said modes,

receiving OFDM symbols on a second number of data-carrying subcarriers; and

processing said OFDM symbols to recover a number of mapped symbols per OFDM symbol that is equal to or less than said second number.

70. The method of claim 69 , wherein said mapped symbols are N-QAM symbols, N being an integer.

71. The method of claim 69 , wherein said processing comprises performing a sequence estimation.

72. The method of claim 71 , wherein said sequence estimation is based on maximum-likelihood sequence estimation.

73. The method of claim 69 , comprising:

while said receiver operates in said first of said modes and a modeling circuit is enabled:

generating, via a model generated by said modeling circuit, reconstructed physical subcarrier values; and

while said receiver operates in said second of said modes, said modeling circuit is disabled.

74. The method of claim 69 , comprising configuring said receiver between said first and said second of said modes during operation based on one or more of: feedback, channel or other communication conditions, network controller, application, and user input.

75. The method of claim 69 , wherein said second number is different than said first number.

76. A method performed by an electronic receiver that comprises a modeling circuit and operates in at least two modes, said method comprising:

while said receiver operates in a first of said modes:

receiving OFDM symbols on a first number of data-carrying subcarriers; and

processing said OFDM symbols to recover a number of mapped symbols per OFDM symbol that is greater than said first number;

enabling said modeling circuit; and

generating, via said modeling circuit, reconstructed physical subcarrier values; and

while said receiver operates in a second of said modes,

receiving OFDM symbols on a second number of data-carrying subcarriers; and

processing said OFDM symbols to recover a number of mapped symbols per OFDM symbol that is equal to or less than said second number; and

disabling said modeling circuit.

77. The method of claim 76 , wherein said mapped symbols are N-QAM symbols, N being an integer.

78. The method of claim 76 , wherein said processing comprises performing a sequence estimation.

79. The method of claim 78 , wherein said sequence estimation is based on maximum-likelihood sequence estimation.

80. The method of claim 76 , comprising configuring said receiver between said first and said second of said modes during operation based on one or more of: feedback, channel or other communication conditions, network controller, application, and user input.

81. The method of claim 76 , wherein said second number is different than said first number.