Non-linear LLR look-up tables
In one implementation, the disclosure provides a system including a detector configured to generate an output of a first log-likelihood ratio for each bit in an input data stream. The system also includes at least one look-up table providing a mapping of the first log-likelihood ratio to a second log-likelihood ratio. The mapping between the first log-likelihood ratio and the second log-likelihood ratio is non-linear. The system also includes a decoder configured to generate an output data stream using the second log-likelihood ratio to generate a value for each bit in the input data stream.
1. A system comprising:
a detector configured to generate an output of a first log-likelihood ratio for one or more of a plurality of bits in an input data stream;
a first look-up table providing a mapping of the first log-likelihood ratio to a second log-likelihood ratio, the mapping between the first log-likelihood ratio and the second log-likelihood ratio being non-linear, wherein the first look-up table is selected based on a programmable iteration count; and
a decoder configured to generate an output data stream using the second log-likelihood ratio to generate a value for each bit in the input data stream.
2. The system of claim 1 , wherein the first look-up table is selected based on a density parameter of a storage medium programmable iteration count.
3. The system of claim 1 , wherein the detector is further configured to generate an output of an estimated bit value for each bit in the input data stream.
4. The system of claim 1 , wherein the decoder is further configured to check the input data stream for convergence.
5. The system of claim 4 , wherein the decoder is further configured to generate a third log-likelihood ratio for each bit in the input data stream when the input data stream has not converged.
6. The system of claim 5 , further comprising:
a second look-up table providing a mapping of the third log-likelihood ratio to a fourth log-likelihood ratio, the mapping between the third log-likelihood ratio and the fourth log-likelihood ratio being non-linear.
7. The system of claim 6 , wherein the second look-up table is selected based on a programmable iteration count.
8. The system of claim 7 , wherein the detector is further configured to generate a fifth log-likelihood ratio based on the fourth log-likelihood ratio.
9. A method comprising:
generating a first log-likelihood ratio for one or more of a plurality of bits in an input data stream read from a storage medium;
mapping the first log-likelihood ratio to a second log-likelihood ratio using at least one look-up table, the mapping between the first log-likelihood ratio and the second-log likelihood ratio being non-linear, wherein the at least one look-up table is selected based on a programmable iteration count; and
generating an output data stream using the second log-likelihood ratio to generate a value for each bit in the input data stream.
10. The method of claim 9 , wherein the first look-up table is selected based on a density parameter of the storage medium.
11. The method of claim 9 , further comprising:
generating an output of an estimated bit value for each bit in the input data stream.
12. The method of claim 11 , further comprising:
checking the input data stream for convergence.
13. The method of claim 11 , further comprising:
generating a third log-likelihood ratio for each bit in the input data stream when the input data stream has not converged.
14. The method of claim 13 , further comprising:
mapping a third log-likelihood ratio to a fourth log-likelihood ratio using a second look-up table, the mapping between the third log-likelihood ratio and the fourth log-likelihood ratio being non-linear.
15. The method of claim 14 , wherein the second look-up table is selected based on a programmable iteration count.
16. One or more non-transitory computer-readable storage media storing therein computer-executable instructions for executing on a computer system a computer process, the computer process comprising:
generating a first log-likelihood ratio for one or more of a plurality of bits in an input data stream;
mapping the first log-likelihood ratio to a second log-likelihood ratio using at least one look-up table, the mapping between the first log-likelihood ratio and the second-log likelihood ratio being non-linear, wherein the at least one look-up table is selected based on a programmable iteration count; and
generating an output data stream using the second log-likelihood ratio to generate a value for each bit in the input data stream.
17. The one or more non-transitory computer-readable storage media of claim 16 , wherein the first look-up table is selected based on a density parameter of a storage medium.
18. The one or more non-transitory computer-readable storage media of claim 16 , wherein the computer process further comprises:
generating an output of an estimated bit value for each bit in the input data stream.
19. The one or more non-transitory computer-readable storage media of claim 16 , wherein the computer process further comprises:
checking the input data stream for convergence.
20. The one or more non-transitory computer-readable storage media of claim 16 , wherein the computer process further comprises:
generating a third log-likelihood ratio for each bit in the input data stream when the input data stream has not converged.