What is claimed is:
1. A decoder that is operable to decode a Low Density Parity Check (LDPC) coded signal, the decoder comprising:
a Sum-Product (SP) soft decision decoder that performs a plurality of soft decision decoding iterations to generate a plurality of soft decisions corresponding to bits within the LDPC coded signal;
wherein the SP soft decision decoder generates a first plurality of hard decisions using the plurality of soft decisions generated during at least one soft decision decoding iteration of the plurality of soft decision decoding iterations; and
a Bit-Flip (BF) hard decision decoder that performs a plurality of hard decision decoding iterations on the first plurality of hard decisions generated by the SP soft decision decoder to generate a second plurality of hard decisions.
2. The decoder of claim 1, wherein the plurality of soft decision decoding iterations performed by the SP soft decision decoder is a predetermined number of soft decision decoding iterations.
3. The decoder of claim 1, wherein the at least one soft decision decoding iteration is a last soft decision decoding iteration of the plurality of soft decision decoding iterations that is performed by the SP soft decision decoder when a number of bit errors within the plurality of soft decisions is less than a predetermined threshold.
4. The decoder of claim 1, wherein the plurality of hard decision decoding iterations performed by the BF hard decision decoder is a predetermined number of hard decision decoding iterations.
5. The decoder of claim 1, wherein a last hard decision decoding iteration of the plurality of hard decision decoding iterations is performed by the BF hard decision decoder when a number of bit errors within the plurality of hard decisions is less than a predetermined threshold.
6. The decoder of claim 1, wherein the SP soft decision decoder performs not more that 6 soft decision decoding iterations; and
wherein the BF hard decision decoder performs not more than 2 hard decision decoding iterations.
7. The decoder of claim 1, wherein information corresponding to a plurality of variable nodes is initialized using hard decisions generated from a plurality of metrics that is based on a plurality of received symbols within the LDPC coded signal and channel information corresponding to a communication channel over which the LDPC coded signal has been communicated; and
wherein the initialized information corresponding to the plurality of variable nodes is used by the SP soft decision decoder before performing a first soft decision decoding iteration of the plurality of soft decision decoding iterations.
8. The decoder of claim 1, wherein a plurality of metrics is based on a plurality of received symbols within the LDPC coded signal and channel information corresponding to a communication channel over which the LDPC coded signal has been communicated;
wherein metrics within the plurality of metrics are selectively scaled, based on a Signal to Noise Ratio (SNR) of the communication channel, to generate a plurality of scaled metrics;
wherein information corresponding to a plurality of variable nodes is initialized using hard decisions generated from the plurality of scaled metrics; and
wherein the initialized information corresponding to the plurality of variable nodes is used by the SP soft decision decoder before performing a first soft decision decoding iteration of the plurality of soft decision decoding iterations.
9. The decoder of claim 1, further comprising a syndrome error detection functional block that is operable to detect a bit error within the second plurality of hard decisions after the BF hard decision decoder performs the plurality of hard decision decoding iterations on the first plurality of hard decisions generated by the SP soft decision decoder.
10. The decoder of claim 9, wherein the SP soft decision decoder performs an additional plurality of soft decision decoding iterations when the syndrome error detection functional block detects the bit error within the second plurality of hard decisions.
11. The decoder of claim 10, wherein the BF hard decision decoder outputs a hard decision decoding result when the SP soft decision decoder fails to eliminate the bit error after performing the additional plurality of soft decision decoding iterations; and
wherein the hard decision decoding result output from the BF hard decision decoder includes an estimated codeword of the LDPC coded signal.
12. The decoder of claim 10, wherein information corresponding to a plurality of variable nodes is initialized using hard decisions generated from a plurality of metrics that is based on a plurality of received symbols within the LDPC coded signal and channel information corresponding to a communication channel over which the LDPC coded signal has been communicated; and
wherein the initialized information corresponding to the plurality of variable nodes is used by the SP soft decision decoder before performing a first soft decision decoding iteration of the additional plurality of soft decision decoding iterations.
13. The decoder of claim 10, wherein a plurality of metrics is based on a plurality of received symbols within the LDPC coded signal and channel information corresponding to a communication channel over which the LDPC coded signal has been communicated;
wherein metrics within the plurality of metrics are selectively scaled, based on a Signal to Noise Ratio (SNR) of the communication channel, to generate a plurality of scaled metrics;
wherein information corresponding to a plurality of variable nodes is initialized using hard decisions generated from the plurality of scaled metrics; and
wherein the initialized information corresponding to the plurality of variable nodes is used by the SP soft decision decoder before performing a first soft decision decoding iteration of the additional plurality of soft decision decoding iterations.
14. The decoder of claim 1, wherein the SP soft decision decoder performs momentum modified SP soft decision decoding processing that involves updating the plurality of soft decisions using information corresponding to 2 previous soft decision decoding iterations of the plurality of soft decision decoding iterations.
15. The decoder of claim 1, wherein the decoder is implemented within a communication receiver; and
the communication receiver is contained within at least one of a satellite communication system, a High Definition Television (HDTV) communication system, a cellular communication system, a microwave communication system, a point-to-point communication system, a uni-directional communication system, a bi-directional communication system, a one to many communication system, and a fiber-optic communication system.
16. A decoder that is operable to decode a Low Density Parity Check (LDPC) coded signal, the decoder comprising:
a Sum-Product (SP) soft decision decoder that performs a plurality of soft decision decoding iterations to generate a plurality of soft decisions corresponding to bits within the LDPC coded signal;
wherein the SP soft decision decoder performs momentum modified SP soft decision decoding processing that involves updating the plurality of soft decisions using information corresponding to 2 previous soft decision decoding iterations of the plurality of soft decision decoding iterations;
wherein the SP soft decision decoder generates a first plurality of hard decisions using the plurality of soft decisions generated during at least one soft decision decoding iteration of the plurality of soft decision decoding iterations;
a Bit-Flip (BF) hard decision decoder that performs a plurality of hard decision decoding iterations on the first plurality of hard decisions generated by the SP soft decision decoder to generate a second plurality of hard decisions;
a syndrome error detection functional block that is operable to detect a bit error within the second plurality of hard decisions after the BF hard decision decoder performs the plurality of hard decision decoding iterations on the first plurality of hard decisions generated by the SP soft decision decoder; and
wherein the SP soft decision decoder performs an additional plurality of soft decision decoding iterations when the syndrome error detection functional block detects the bit error within the second plurality of hard decisions.
17. The decoder of claim 16, wherein the plurality of soft decision decoding iterations performed by the SP soft decision decoder is a predetermined number of soft decision decoding iterations.
18. The decoder of claim 16, wherein the at least one soft decision decoding iteration is a last soft decision decoding iteration of the plurality of soft decision decoding iterations that is performed by the SP soft decision decoder when a number of bit errors within the plurality of soft decisions is less than a predetermined threshold.
19. The decoder of claim 16, wherein the plurality of hard decision decoding iterations performed by the BF hard decision decoder is a predetermined plurality of hard decision decoding iterations.
20. The decoder of claim 16, wherein a last hard decision decoding iteration of the plurality of hard decision decoding iterations is performed by the BF hard decision decoder when a number of bit errors within the plurality of hard decisions is less than a predetermined threshold.
21. The decoder of claim 16, wherein the SP soft decision decoder performs not more that 6 soft decision decoding iterations; and
wherein the BF hard decision decoder performs not more than 2 hard decision decoding iterations.
22. The decoder of claim 16, wherein information corresponding to a plurality of variable nodes is initialized using hard decisions generated from a plurality of metrics that is based on a plurality of received symbols within the LDPC coded signal and channel information corresponding to a communication channel over which the LDPC coded signal has been communicated; and
wherein the initialized information corresponding to the plurality of variable nodes is used by the SP soft decision decoder before performing a first soft decision decoding iteration of the plurality of soft decision decoding iterations.
23. The decoder of claim 16, wherein a plurality of metrics is based on a plurality of received symbols within the LDPC coded signal and channel information corresponding to a communication channel over which the LDPC coded signal has been communicated;
wherein metrics within the plurality of metrics are selectively scaled, based on a Signal to Noise Ratio (SNR) of the communication channel, to generate a plurality of scaled metrics;
wherein information corresponding to a plurality of variable nodes is initialized using hard decisions generated from the plurality of scaled metrics; and
wherein the initialized information corresponding to the plurality of variable nodes is used by the SP soft decision decoder before performing a first soft decision decoding iteration of the plurality of soft decision decoding iterations.
24. The decoder of claim 16, wherein the BF hard decision decoder outputs a hard decision decoding result when the SP soft decision decoder fails to eliminate the bit error after performing the additional plurality of soft decision decoding iterations; and
wherein the hard decision decoding result output from the BF hard decision decoder includes an estimated codeword of the LDPC coded signal.
25. The decoder of claim 16, wherein information corresponding to a plurality of variable nodes is initialized using hard decisions generated from a plurality of metrics that is based on a plurality of received symbols within the LDPC coded signal and channel information corresponding to a communication channel over which the LDPC coded signal has been communicated; and
wherein the initialized information corresponding to the plurality of variable nodes is used by the SP soft decision decoder before performing a first soft decision decoding iteration of the additional plurality of soft decision decoding iterations.
26. The decoder of claim 16, wherein a plurality of metrics is based on a plurality of received symbols within the LDPC coded signal and channel information corresponding to a communication channel over which the LDPC coded signal has been communicated;
wherein metrics within the plurality of metrics are selectively scaled, based on a Signal to Noise Ratio (SNR) of the communication channel, to generate a plurality of scaled metrics;
wherein information corresponding to a plurality of variable nodes is initialized using hard decisions generated from the plurality of scaled metrics; and
wherein the initialized information corresponding to the plurality of variable nodes is used by the SP soft decision decoder before performing a first soft decision decoding iteration of the additional plurality of soft decision decoding iterations.
27. The decoder of claim 16, wherein the SP soft decision decoder performs momentum modified SP soft decision decoding processing that involves updating the plurality of soft decisions using information corresponding to 2 previous soft decision decoding iterations of the plurality of soft decision decoding iterations.
28. The decoder of claim 16, wherein the decoder is implemented within a communication receiver; and
the communication receiver is contained within at least one of a satellite communication system, a High Definition Television (HDTV) communication system, a cellular communication system, a microwave communication system, a point-to-point communication system, a uni-directional communication system, a bi-directional communication system, a one to many communication system, and a fiber-optic communication system.
29. A decoder that is operable to decode a Low Density Parity Check (LDPC) coded signal, the decoder comprising:
a Sum-Product (SP) soft decision decoder that performs a plurality of soft decision decoding iterations to generate a plurality of soft decisions corresponding to bits within the LDPC coded signal;
wherein the SP soft decision decoder generates a first plurality of hard decisions using the plurality of soft decisions generated during at least one soft decision decoding iteration of the plurality of soft decision decoding iterations;
a Bit-Flip (BF) hard decision decoder that performs a plurality of hard decision decoding iterations on the first plurality of hard decisions generated by the SP soft decision decoder to generate a second plurality of hard decisions;
wherein information corresponding to a plurality of variable nodes is initialized using hard decisions generated from a plurality of metrics that is based on a plurality of received symbols within the LDPC coded signal and channel information corresponding to a communication channel over which the LDPC coded signal has been communicated; and
wherein the initialized information corresponding to the plurality of variable nodes is used by the SP soft decision decoder before performing a first soft decision decoding iteration of the plurality of soft decision decoding iterations.
30. The decoder of claim 29, wherein the plurality of soft decision decoding iterations performed by the SP soft decision decoder is a predetermined number of soft decision decoding iterations.
31. The decoder of claim 29, wherein the at least one soft decision decoding iteration is a last soft decision decoding iteration of the plurality of soft decision decoding iterations that is performed by the SP soft decision decoder when a number of bit errors within the plurality of soft decisions is less than a predetermined threshold.
32. The decoder of claim 29, wherein the plurality of hard decision decoding iterations performed by the BF hard decision decoder is a predetermined number of hard decision decoding iterations.
33. The decoder of claim 29, wherein a last hard decision decoding iteration of the plurality of hard decision decoding iterations is performed by the BF hard decision decoder when a number of bit errors within the plurality of hard decisions is less than a predetermined threshold.
34. The decoder of claim 29, wherein the SP soft decision decoder performs not more that 6 soft decision decoding iterations; and
wherein the BF hard decision decoder performs not more than 2 hard decision decoding iterations.
35. The decoder of claim 29, further comprising a syndrome error detection functional block that is operable to detect a bit error within the second plurality of hard decisions after the BF hard decision decoder performs the plurality of hard decision decoding iterations on the first plurality of hard decisions generated by the SP soft decision decoder.
36. The decoder of claim 35, wherein the SP soft decision decoder performs an additional plurality of soft decision decoding iterations when the syndrome error detection functional block detects the bit error within the second plurality of hard decisions.
37. The decoder of claim 36, wherein the BF hard decision decoder outputs a hard decision decoding result when the SP soft decision decoder fails to eliminate the bit error after performing the additional plurality of soft decision decoding iterations; and
wherein the hard decision decoding result output from the BF hard decision decoder includes an estimated codeword of the LDPC coded signal.
38. The decoder of claim 36, wherein information corresponding to a plurality of variable nodes is initialized using hard decisions generated from a plurality of metrics that is based on a plurality of received symbols within the LDPC coded signal and channel information corresponding to a communication channel over which the LDPC coded signal has been communicated; and
wherein the initialized information corresponding to the plurality of variable nodes is used by the SP soft decision decoder before performing a first soft decision decoding iteration of the additional plurality of soft decision decoding iterations.
39. The decoder of claim 36, wherein a plurality of metrics is based on a plurality of received symbols within the LDPC coded signal and channel information corresponding to a communication channel over which the LDPC coded signal has been communicated;
wherein metrics within the plurality of metrics are selectively scaled, based on a Signal to Noise Ratio (SNR) of the communication channel, to generate a plurality of scaled metrics;
wherein information corresponding to a plurality of variable nodes is initialized using hard decisions generated from the plurality of scaled metrics; and
wherein the initialized information corresponding to the plurality of variable nodes is used by the SP soft decision decoder before performing a first soft decision decoding iteration of the additional plurality of soft decision decoding iterations.
40. The decoder of claim 29, wherein the SP soft decision decoder performs momentum modified SP soft decision decoding processing that involves updating the plurality of soft decisions using information corresponding to 2 previous soft decision decoding iterations of the plurality of soft decision decoding iterations.
41. The decoder of claim 29, wherein the decoder is implemented within a communication receiver; and
the communication receiver is contained within at least one of a satellite communication system, a High Definition Television (HDTV) communication system, a cellular communication system, a microwave communication system, a point-to-point communication system, a uni-directional communication system, a bi-directional communication system, a one to many communication system, and a fiber-optic communication system.
42. A decoder that is operable to decode a Low Density Parity Check (LDPC) coded signal, the decoder comprising:
a Sum-Product (SP) soft decision decoder that performs a plurality of soft decision decoding iterations to generate a plurality of soft decisions corresponding to bits within the LDPC coded signal;
wherein the SP soft decision decoder generates a first plurality of hard decisions using the plurality of soft decisions generated during at least one soft decision decoding iteration of the plurality of soft decision decoding iterations;
a Bit-Flip (BF) hard decision decoder that performs a plurality of hard decision decoding iterations on the first plurality of hard decisions generated by the SP soft decision decoder to generate a second plurality of hard decisions;
wherein a plurality of metrics is based on a plurality of received symbols within the LDPC coded signal and channel information corresponding to a communication channel over which the LDPC coded signal has been communicated;
wherein metrics within the plurality of metrics are selectively scaled, based on a Signal to Noise Ratio (SNR) of the communication channel, to generate a plurality of scaled metrics;
wherein information corresponding to a plurality of variable nodes is initialized using hard decisions generated from the plurality of scaled metrics; and
wherein the initialized information corresponding to the plurality of variable nodes is used by the SP soft decision decoder before performing a first soft decision decoding iteration of the plurality of soft decision decoding iterations.
43. The decoder of claim 42, wherein the plurality of soft decision decoding iterations performed by the SP soft decision decoder is a predetermined number of soft decision decoding iterations.
44. The decoder of claim 42, wherein the at least one soft decision decoding iteration is a last soft decision decoding iteration of the plurality of soft decision decoding iterations that is performed by the SP soft decision decoder when a number of bit errors within the plurality of soft decisions is less than a predetermined threshold.
45. The decoder of claim 42, wherein the plurality of hard decision decoding iterations performed by the BF hard decision decoder is a predetermined number of hard decision decoding iterations.
46. The decoder of claim 42, wherein a last hard decision decoding iteration of the plurality of hard decision decoding iterations is performed by the BF hard decision decoder when a number of bit errors within the plurality of hard decisions is less than a predetermined threshold.
47. The decoder of claim 42, wherein the SP soft decision decoder performs not more that 6 soft decision decoding iterations; and
wherein the BF hard decision decoder performs not more than 2 hard decision decoding iterations.
48. The decoder of claim 42, further comprising a syndrome error detection functional block that is operable to detect a bit error within the second plurality of hard decisions after the BF hard decision decoder performs the plurality of hard decision decoding iterations on the first plurality of hard decisions generated by the SP soft decision decoder.
49. The decoder of claim 48, wherein the SP soft decision decoder performs an additional plurality of soft decision decoding iterations when the syndrome error detection functional block detects the bit error within the second plurality of hard decisions.
50. The decoder of claim 49, wherein the BF hard decision decoder outputs a hard decision decoding result when the SP soft decision decoder fails to eliminate the bit error after performing the additional plurality of soft decision decoding iterations; and
wherein the hard decision decoding result output from the BF hard decision decoder includes an estimated codeword of the LDPC coded signal.
51. The decoder of claim 49, wherein information corresponding to a plurality of variable nodes is initialized using hard decisions generated from a plurality of metrics that is based on a plurality of received symbols within the LDPC coded signal and channel information corresponding to a communication channel over which the LDPC coded signal has been communicated; and
wherein the initialized information corresponding to the plurality of variable nodes is used by the SP soft decision decoder before performing a first soft decision decoding iteration of the additional plurality of soft decision decoding iterations.
52. The decoder of claim 49, wherein a plurality of metrics is based on a plurality of received symbols within the LDPC coded signal and channel information corresponding to a communication channel over which the LDPC coded signal has been communicated;
wherein metrics within the plurality of metrics are selectively scaled, based on a Signal to Noise Ratio (SNR) of the communication channel, to generate a plurality of scaled metrics;
wherein information corresponding to a plurality of variable nodes is initialized using hard decisions generated from the plurality of scaled metrics; and
wherein the initialized information corresponding to the plurality of variable nodes is used by the SP soft decision decoder before performing a first soft decision decoding iteration of the additional plurality of soft decision decoding iterations.
53. The decoder of claim 42, wherein the SP soft decision decoder performs momentum modified SP soft decision decoding processing that involves updating the plurality of soft decisions using information corresponding to 2 previous soft decision decoding iterations of the plurality of soft decision decoding iterations.
54. The decoder of claim 42, wherein the decoder is implemented within a communication receiver; and
the communication receiver is contained within at least one of a satellite communication system, a High Definition Television (HDTV) communication system, a cellular communication system, a microwave communication system, a point-to-point communication system, a uni-directional communication system, a bi-directional communication system, a one to many communication system, and a fiber-optic communication system.
55. A method that decodes a Low Density Parity Check (LDPC) coded signal, the method comprising:
Sum-Product (SP) soft decision decoding to perform a plurality of soft decision decoding iterations to generate a plurality of soft decisions corresponding to bits within the LDPC coded signal;
generating a first plurality of hard decisions using the soft decisions generated during at least one soft decision decoding iteration of the plurality of soft decision decoding iterations; and
Bit-Flip (BF) hard decision decoding to perform a plurality of hard decision decoding iterations on the first plurality of hard decisions generated by the SP soft decision decoding to generate a second plurality of hard decisions.
56. The method of claim 55, wherein the plurality of soft decision decoding iterations is a predetermined number of soft decision decoding iterations.
57. The method of claim 55, wherein the at least one soft decision decoding iteration is a last soft decision decoding iteration of the plurality of soft decision decoding iterations that is performed when a number of bit errors within the plurality of soft decisions is less than a predetermined threshold.
58. The method of claim 55, wherein the plurality of hard decision decoding iterations is a predetermined number of hard decision decoding iterations.
59. The method of claim 55, wherein a last hard decision decoding iteration of the plurality of hard decision decoding iterations is performed when a number of bit errors within the second plurality of hard decisions is less than a predetermined threshold.
60. The method of claim 55, wherein the SP soft decision decoding performs not more that 6 soft decision decoding iterations; and
wherein the BF hard decision decoding performs not more than 2 hard decision decoding iterations.
61. The method of claim 55, further comprising:
initializing information corresponding to a plurality of variable nodes using hard decisions generated from a plurality of metrics that is based on a plurality of received symbols within the LDPC coded signal and channel information corresponding to a communication channel over which the LDPC coded signal has been communicated; and
using the initialized information corresponding to the plurality of variable nodes to initialize a first soft decision decoding iteration of the plurality of soft decision decoding iterations.
62. The method of claim 55, wherein a plurality of metrics is based on a plurality of received symbols within the LDPC coded signal and channel information corresponding to a communication channel over which the LDPC coded signal has been communicated;
further comprising:
selectively scaling the plurality of metrics, based on a Signal to Noise Ratio (SNR) of the communication channel, to generate a plurality of scaled metrics;
generating hard decisions from the plurality of scaled metrics;
initializing information corresponding to a plurality of variable nodes using the hard decisions generated from the plurality of scaled metrics; and
using the initialized information corresponding to the plurality of variable nodes to initialize a first soft decision decoding iteration of the plurality of soft decision decoding iterations.
63. The method of claim 55, further comprising:
detecting a bit error within the second plurality of hard decisions after the plurality of hard decision decoding iterations is made on the first plurality of hard decisions generated during the at least one soft decision decoding iteration of the plurality of soft decision decoding iterations.
64. The method of claim 63, further comprising:
performing an additional plurality of soft decision decoding iterations when a bit error has been detected within the second plurality of hard decisions.
65. The method of claim 64, further comprising:
outputting a hard decision decoding result when the additional plurality of soft decision decoding iterations fails to eliminate the bit error; and
wherein the hard decision decoding result output includes an estimated codeword of the LDPC coded signal.
66. The method of claim 64, further comprising:
initializing information corresponding to a plurality of variable nodes using hard decisions generated from a plurality of metrics that is based on a plurality of received symbols within the LDPC coded signal and channel information corresponding to a communication channel over which the LDPC coded signal has been communicated; and
using the initialized information corresponding to the plurality of variable nodes to initialize a first soft decision decoding iteration of the additional plurality of soft decision decoding iterations.
67. The method of claim 64, wherein a plurality of metrics is based on a plurality of received symbols within the LDPC coded signal and channel information corresponding to a communication channel over which the LDPC coded signal has been communicated;
further comprising:
selectively scaling the plurality of metrics, based on a Signal to Noise Ratio (SNR) of the communication channel, to generate a plurality of scaled metrics;
generating hard decisions from the plurality of scaled metrics;
initializing information corresponding to a plurality of variable nodes using the hard decisions generated from the plurality of scaled metrics; and
using the initialized information corresponding to the plurality of variable nodes to initialize a first soft decision decoding iteration of the additional plurality of soft decision decoding iterations.
68. The method of claim 55, wherein the SP soft decision decoding involves performing momentum modified SP soft decision decoding processing that involves updating the plurality of soft decisions using information corresponding to 2 previous soft decision decoding iterations of the plurality of soft decision decoding iterations.
69. The method of claim 55, wherein the method is performed within a decoder that is implemented within a communication receiver; and
the communication receiver is contained within at least one of a satellite communication system, a High Definition Television (HDTV) communication system, a cellular communication system, a microwave communication system, a point-to-point communication system, a uni-directional communication system, a bi-directional communication system, a one to many communication system, and a fiber-optic communication system.
70. A method that decodes a Low Density Parity Check (LDPC) coded signal, the method comprising:
Sum-Product (SP) soft decision decoding to perform a plurality of soft decision decoding iterations to generate a plurality of soft decisions corresponding to bits within the LDPC coded signal;
wherein the SP soft decision decoding performs momentum modified SP soft decision decoding processing that involves updating the plurality of soft decisions using information corresponding to 2 previous soft decision decoding iterations of the plurality of soft decision decoding iterations;
generating a first plurality of hard decisions using the soft decisions generated during at least one soft decision decoding iteration of the plurality of soft decision decoding iterations;
Bit-Flip (BF) hard decision decoding to perform a plurality of hard decision decoding iterations on the first plurality of hard decisions generated by the SP soft decision decoding to generate a second plurality of hard decisions;
detecting a bit error within the second plurality of hard decisions after the plurality of hard decision decoding iterations is made on the first plurality of hard decisions generated during the at least one soft decision decoding iteration of the plurality of soft decision decoding iterations; and
additional SP soft decision decoding to perform an additional plurality of soft decision decoding iterations when a bit error has been detected within the second plurality of hard decisions.
71. The method of claim 70, wherein the plurality of soft decision decoding iterations is a predetermined number of soft decision decoding iterations.
72. The method of claim 70, wherein the at least one soft decision decoding iteration is a last soft decision decoding iteration of the plurality of soft decision decoding iterations that is performed when a number of bit errors within the plurality of soft decisions is less than a predetermined threshold.
73. The method of claim 70, wherein the plurality of hard decision decoding iterations is a predetermined number of hard decision decoding iterations.
74. The method of claim 70, wherein a last hard decision decoding iteration of the plurality of hard decision decoding iterations is performed when a number of bit errors within the plurality of hard decisions is less than a predetermined threshold.
75. The method of claim 70, wherein the SP soft decision decoding performs not more that 6 soft decision decoding iterations; and
wherein the BF hard decision decoding performs not more than 2 hard decision decoding iterations.
76. The method of claim 70, further comprising:
initializing information corresponding to a plurality of variable nodes using hard decisions generated from a plurality of metrics that is based on a plurality of received symbols within the LDPC coded signal and channel information corresponding to a communication channel over which the LDPC coded signal has been communicated; and
using the initialized information corresponding to the plurality of variable nodes to initialize a first soft decision decoding iteration of the plurality of soft decision decoding iterations.
77. The method of claim 70, wherein a plurality of metrics is based on a plurality of received symbols within the LDPC coded signal and channel information corresponding to a communication channel over which the LDPC coded signal has been communicated;
further comprising:
selectively scaling the plurality of metrics, based on a Signal to Noise Ratio (SNR) of the communication channel, to generate a plurality of scaled metrics;
generating hard decisions from the plurality of scaled metrics;
initializing information corresponding to a plurality of variable nodes using the hard decisions generated from the plurality of scaled metrics; and
using the initialized information corresponding to the plurality of variable nodes to initialize a first soft decision decoding iteration of the plurality of soft decision decoding iterations.
78. The method of claim 70, further comprising:
outputting a hard decision decoding result when the additional plurality of soft decision decoding iterations fails to eliminate the bit error; and
wherein the hard decision decoding result output includes an estimated codeword of the LDPC coded signal.
79. The method of claim 70, further comprising:
initializing information corresponding to a plurality of variable nodes using hard decisions generated from a plurality of metrics that is based on a plurality of received symbols within the LDPC coded signal and channel information corresponding to a communication channel over which the LDPC coded signal has been communicated; and
using the initialized information corresponding to the plurality of variable nodes to initialize a first soft decision decoding iteration of the additional plurality of soft decision decoding iterations.
80. The method of claim 70, wherein a plurality of metrics is based on a plurality of received symbols within the LDPC coded signal and channel information corresponding to a communication channel over which the LDPC coded signal has been communicated;
further comprising:
selectively scaling the plurality of metrics, based on a Signal to Noise Ratio (SNR) of the communication channel, to generate a plurality of scaled metrics;
generating hard decisions from the plurality of scaled metrics;
initializing information corresponding to a plurality of variable nodes using the hard decisions generated from the plurality of scaled metrics; and
using the initialized information corresponding to the plurality of variable nodes to initialize a first soft decision decoding iteration of the additional plurality of soft decision decoding iterations.
81. The method of claim 70, wherein the SP soft decision decoding involves performing momentum modified SP soft decision decoding processing that involves updating the plurality of soft decisions using information corresponding to 2 previous soft decision decoding iterations of the plurality of soft decision decoding iterations.
82. The method of claim 70, wherein the method is performed within a decoder that is implemented within a communication receiver; and
the communication receiver is contained within at least one of a satellite communication system, a High Definition Television (HDTV) communication system, a cellular communication system, a microwave communication system, a point-to-point communication system, a uni-directional communication system, a bi-directional communication system, a one to many communication system, and a fiber-optic communication system.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
What is claimed is:
1. An optical component adapted for attachment to an optical bench, the optical component comprises an alignment feature for positioning the optical component relative to the optical bench, wherein the alignment feature extends into the optical component from an exterior wall, the alignment feature comprising a reentrant sidewall.
2. An optical component as claimed in claim 1, wherein the alignment feature is formed in a bottom face of the optical component.
3. An optical component as claimed in claim 1, wherein a proximal origin of the reentrant sidewall is depressed relative to the exterior wall surrounding the alignment feature.
4. An optical component as claimed in claim 3, wherein the outer exterior wall is bonded to the optical bench.
5. An optical component as claimed in claim 1, wherein the exterior wall surrounding the alignment feature is bonded to the optical bench.
6. An optical component as claimed in claim 1, wherein the exterior wall is depressed relative a surface that is bonded to the optical bench.
7. An optical component as claimed in claim 1, wherein the alignment feature comprises a slot that extends along a length of the optical component.
8. An optical component as claimed in claim 1, wherein the alignment feature comprises a slot that extends along an entire length of the optical component.
9. An optical component as claimed in claim 1, further comprising a coating over the optical component that is used to attach the optical component to the optical bench.
10. An optical component as claimed in claim 9, wherein the coating is between 0.5 and 10 micrometers thick.
11. An optical component as claimed in claim 9, wherein the coating is about 3 micrometers thick.
12. An optical component as claimed in claim 9, wherein the coating is plated on the optical component.
13. An optical component as claimed in claim 9, wherein the coating is sputtered on the optical component.
14. An optical component as claimed in claim 1, further comprising a gold plated layer on the optical component over the alignment feature.
15. An optical component as claimed in claim 1, further comprising multiple alignment features spaced from each other along a width of the optical component.
16. An optical component as claimed in claim 15, further comprising at least two of the alignment features having different widths with respect to each other.
17. An optical component as claimed in claim 1, wherein a waist of the alignment feature is between 10 and 100 micrometers wide.
18. An optical component as claimed in claim 1, wherein a waist of the alignment feature is between 10 and 50 micrometers wide.
19. An optical component as claimed in claim 1, wherein a waist of the alignment feature is about 25 micrometers wide.
20. An optical component as claimed in claim 1, wherein a waist of the alignment feature is about 50 micrometers wide.
21. An optical component as claimed in claim 1, further comprising a gold alloy coating on the optical component over the alignment feature for attaching the optical component to the optical bench.
22. An optical component adapted for precision attachment to an optical bench, the optical component comprising an alignment feature for positioning the optical component relative to the optical bench, wherein the alignment feature extends into the optical component from an exterior wall, the alignment feature comprising two opposed reentrant sidewalls.
23. An optical component as claimed in claim 22, wherein the alignment feature has a frusto-triangular profile.
24. An optical component as claimed in claim 23, wherein a waist of the alignment feature is between 10 and 100 micrometers wide.
25. An optical component as claimed in claim 23, wherein a waist of the alignment feature is between 10 and 50 micrometers wide.
26. An optical component as claimed in claim 22, wherein the alignment feature has an hourglass profile.
27. An optical component as claimed in claim 26, wherein a waist of the alignment feature is between 10 and 100 micrometers wide.
28. An optical component as claimed in claim 26, wherein a waist of the alignment feature is between 10 and 50 micrometers wide.
29. A method for installing an optical component (100) on an optical bench (10), the method comprising:
determining a position of the optical component (100) by reference to an alignment feature (310) formed into an exterior wall (210) of the optical component;
determining a position of the optical bench (10) by reference to a bench alignment feature (22); and
bonding the optical component (100) to the optical bench (10).
30. A method as claimed in claim 29, wherein the step of determining the position of the optical component (100) includes locating a proximal origin (328) of a sidewall (320).
31. A method as claimed in any one of the claims 29, wherein the step of bonding comprises solder bonding the optical component (100) to the optical bench (10).