Hierarchical trellis coded modulation

• US 20050111565A1
• Filed: 10/22/2004
• Published: 05/26/2005
• Est. Priority Date: 10/24/2003
• Status: Active Grant

• Current Assignee: Ikanos Communications Incorporated (Qualcomm, Inc.)
• Original Assignee: Ikanos Communications Incorporated (Qualcomm, Inc.)
• Inventors: Duvaut, Patrick, Pons, Julien, Pierrugues, Laurent, Moreno, Oliver
• Granted Patent: US 7,613,985 B2
• Time in Patent Office: Days
• US Class Current: 375/265
• CPC Class Codes: H04L 1/0041 Arrangements at the transmitter end
• CPC Class Codes: H04L 1/0045 Arrangements at the receiver end
• CPC Class Codes: H04L 1/006 Trellis-coded modulation
• CPC Class Codes: H04L 1/0066 Parallel concatenated codes
• CPC Class Codes: H04L 1/007 Unequal error protection for format H04L1/0078; for codes per se H03M13/35
• CPC Class Codes: H04L 1/208 involving signal re-encoding
• CPC Class Codes: H04L 27/3416 in which the information is carried by both the individual signal points and the subset to which the individual points belong, e.g. using coset coding, lattice coding, or related schemes

Abstract

A system and method for encoding information is disclosed. In one embodiment, information is encoded using a high protection code for the least significant bit and a low protection code for the next three most significant bits. The remaining bits are uncoded. The high protection code may be a turbo code and the low protection code may be a trellis coded modulation code. In this embodiment, the collection of bits is then mapped according to a diagonally shifted QAM constellation technique.

Claims

1. A method of encoding a quantity of electronic information, the method comprising:

encoding a first portion of the quantity of information using a high protection code encoder to produce a first coded portion of information;

encoding a second portion of the quantity of information using a low protection code encoder to produce a second coded portion of information; and

mapping the first coded portion of information, the second coded portion of information, and a third portion of the quantity of information to at least one symbol.

2. The method of claim 1 wherein the high protection code is selected from the group consisting of:

a turbo code and a low-density parity-check code.

3. The method of claim 1 wherein the high protection code does not limit the asymptotic performance of the method of encoding a quantity of electronic information.

4. The method of claim 1 wherein the relation d_free,hpc>

D_N^n+pd_free,lpc is satisfied, wherein d_free,hpc is the free Euclidean distance of the high protection code, d_free,lpc is the free Euclidean distance of the low protection code, and D_N^n+p is a distance coefficient.

5. The method of claim 4 wherein

6. The method of claim 5 wherein the quantity of information is present on a signal comprising a signal set selected from the group consisting of:

1D lattice-type signal sets and 2D lattice-type signal sets.

7. The method of claim 4 wherein D₄¹=D₄²={square root}{square root over (2)}, and D₄³=D₄³=D₄⁴=2.

8. The method of claim 7 wherein the quantity of information is present on a signal comprising a 4D lattice-type signal set.

9. The method of claim 1 wherein the low protection code comprises a trellis coded modulation code.

10. The method of claim 1 wherein the low protection code comprises a Wei code.

11. The method of claim 10 wherein the Wei code is consistent with ITU G.992.1 standard.

12. The method of claim 1 wherein the quantity of information comprises ADSL information.

13. The method of claim 1 wherein the mapping comprises using at least one diagonally shifted quadrature amplitude modulation constellation.

14. The method of claim 1 wherein the first quantity of information comprises a least significant bit.

15. The method of claim 1 wherein the second quantity of information comprises three bits, the three bits excluding a least significant bit.

16. A system for encoding a quantity of electronic information, the system comprising:

a high protection code encoder configured to encode a first portion of the quantity of information to produce a first coded portion of information;

a low protection code encoder configured to encode a second portion of the quantity of information to produce a second coded portion of information; and

a modulator configured to map the first coded portion of information, the second coded portion of information, and a third portion of the quantity of information to at least one symbol.

17. The system of claim 16 wherein the high protection code encoder is selected from the group consisting of:

a turbo code encoder and a low-density parity-check code encoder.

18. The system of claim 16 wherein the high protection code encoder does not limit the asymptotic performance of the system for encoding a quantity of electronic information.

19. The system of claim 16 wherein the relation d_free,hpc>

D_N^n+pd_free,lpc is satisfied, wherein d_free,hpc is the free Euclidean distance of a high protection code implemented by the high protection code encoder, d_free,lpc is the free Euclidean distance of a low protection code implemented by the low protection code encoder, and D_N^n+p is a distance coefficient.

20. The system of claim 19 wherein

21. The system of claim 20 wherein the system is configured to produce a signal compromising a signal set selected from the group consisting of:

1D lattice-type signal sets and 2D lattice-type signal sets.

22. The system of claim 19 wherein D₄¹=D₄²={square root}{square root over (2)}, and D₄³=D₄⁴=2.

23. The system of claim 22 wherein the high protection encoder is configured to produce a signal comprising a 4D lattice-type signal set.

24. The system of claim 16 wherein the low protection code encoder is configured to encode according to trellis coded modulation.

25. The system of claim 16 wherein the low protection code encoder comprises a Wei encoder.

26. The system of claim 25 wherein the Wei encoder is consistent with ITU G.992.1 standard.

27. The system of claim 16 configured to encode ADSL information.

28. The system of claim 16 wherein the modulator is configured to use at least one diagonally shifted quadrature amplitude modulation constellation.

29. The system of claim 16 wherein the high protection code encoder is configured to accept information comprising a least significant bit.

30. The system of claim 16 wherein the low protection code encoder is configured to encode information comprising three bits, the three bits excluding a least significant bit.

31. A method for decoding a quantity of coded electronic information, the method comprising:

at least partially decoding the quantity of coded information using a high protection code decoder to produce a first at least partially decoded quantity of information; and

at least partially decoding the first at least partially decoded quantity of information using a low protection code decoder to produce a second at least partially decoded quantity of information.

32. The method of claim 31 wherein the high protection code is selected from the group consisting of:

a turbo code and a low-density parity-check code.

33. The method of claim 31 wherein the quantity of coded information comprises information coded by a coding method, the coding method including encoding according to the high protection code, wherein the high protection code does not limit the asymptotic performance of the coding method.

34. The method of claim 31 wherein the relation d_free,hpc>

D_N^n+pd_free,lpc is satisfied, wherein d_free,hpc is the free Euclidean distance of the high protection code, d_free,lpc is the free Euclidean distance of the low protection code, and D_N^n+p is a distance coefficient.

35. The method of claim 34 wherein

36. The method of claim 35 wherein the quantity of information is present on a signal comprising a signal set selected from the group consisting of:

1D lattice-type signal sets and 2D lattice-type signal sets.

37. The method of claim 34 wherein D₄¹=D₄²={square root}{square root over (2)}, and D₄³=D₄⁴=2.

38. The method of claim 37 wherein quantity of information is present on a signal comprising a 4D lattice-type signal set.

39. The method of claim 31 wherein the low protection code comprises trellis coded modulation.

40. The method of claim 31 wherein the low protection code comprises a Wei code.

41. The method of claim 40 wherein the Wei code is consistent with ITU G.992.1 standard.

42. The method of claim 31 wherein the quantity of coded information comprises ADSL information.

43. The method of claim 31 further comprising passing a probability from the high protection code decoder to the low protection code decoder.

44. A system for decoding a quantity of coded electronic information, the system comprising:

a high protection code decoder configured to at least partially decode the quantity of information to produce a first at least partially decoded portion of information; and

a low protection code decoder configured to at least partially decode the first at least partially decoded portion of information to produce a second at least partially decoded portion of information.

45. The system of claim 44 wherein the high protection code decoder is selected from the group consisting of:

a turbo code decoder and a low-density parity-check code decoder.

46. The system of claim 44 wherein the system is configured to accept information encoded by an encoding system comprising a high protection code encoder, wherein the high protection code encoder does not limit the asymptotic performance of the encoding system.

47. The system of claim 44 wherein the system is configured to accept information encoded according to a high protection code and a low protection code, wherein the relation d_free,hpc>

D_N^n+pd_free,lpc is satisfied, wherein d_free,hpc is the free Euclidean distance of the high protection code, d_free,lpc is the free Euclidean distance of the low protection code, and D_N^n+p is a distance coefficient.

48. The system of claim 47 wherein

49. The system of claim 48 wherein the quantity of information is present on a signal comprising a signal set selected from the group consisting of:

1D lattice-type signal sets and 2D lattice-type signal sets.

50. The system of claim 47 wherein D₄¹=D₄²={square root}{square root over (2)}, and D₄³=D₄⁴=2.

51. The system of claim 50 wherein the quantity of information is present on a signal comprising a 4D lattice-type signal set.

52. The system of claim 44 wherein the low protection code decoder is configured to decode information comprising trellis coded modulation information.

53. The system of claim 44 wherein the low protection code decoder comprises a Wei decoder.

54. The system of claim 53 wherein the Wei decoder is consistent with ITU G.992.1 standard.

55. The system of claim 44 configured to decode ADSL information.

56. The system of claim 44 wherein the high protection code decoder is configured to pass a probability to the low protection code decoder.

57. A method of encoding a sequence of bits, the method comprising:

encoding a first portion of the sequence of bits according to a turbo code, the first portion of encoded bits including a least significant bit, to produce first encoded bits;

encoding a second portion of the sequence of bits according to a trellis code to produce second encoded bits; and

mapping a third portion of the sequence of bits, the first encoded bits, and the second encoded bits to at least one symbol.

58. A system for encoding a quantity of electronic information, the system comprising:

means for encoding a first portion of the quantity of information according to a high protection code to produce a first coded portion of information;

means for encoding a second portion of the quantity of information according to a low protection code to produce a second coded portion of information; and

means for mapping the first coded portion of information, the second coded portion of information, and a third portion of the quantity of information to at least one symbol.

59. A computer readable medium containing instructions configured to cause a computer to:

encode a first portion of a quantity of information according to a high protection code to produce a first coded portion of information;

encode a second portion of the quantity of information according to a low protection code to produce a second coded portion of information; and

map the first coded portion of information, the second coded portion of information, and a third portion of the quantity of information to at least one symbol.

60. A method of decoding a sequence of bits, the method comprising:

at least partially decoding the sequence of bits using a turbo code decoder to produce a first at least partially decoded sequence of bits; and

at least partially decoding the first at least partially decoded sequence of bits using a trellis coded modulation decoder to produce a second at least partially decoded sequence of bits.

61. A system for decoding a quantity of coded electronic information, the system comprising:

means for at least partially decoding the quantity of coded information according to a high protection code to produce a first at least partially decoded quantity of information; and

means for at least partially decoding the first at least partially decoded quantity of information according to a low protection code to produce a second at least partially decoded quantity of information.

62. A computer readable medium containing instructions configured to cause a computer to:

at least partially decode a quantity of coded information according to a high protection code to produce a first at least partially decoded quantity of information; and

at least partially decode the first at least partially decoded quantity of information according to a low protection code to produce a second at least partially decoded quantity of information.