Normalization factor adaptation for LDPC decoding for hard disk drive systems
View Patent ↗An adaptation technique for decoding low-density parity-check (LDPC) codes for hard disk drive (HDDs) systems is disclosed. The method includes tuning the normalization factor for LDPC decoding for each data zone and read head during the test stage of manufacturing. The LDPC decoder can be either a sum-product algorithm (SPA) decoder or a Min-Sum decoder. The channel detector can be any soft-output detector, such as a soft-output Viterbit detector (SOVA), a BCJR detector, a pattern-dependent noise-predictive (PDNP) detector, or a bi-directional pattern-dependent noise-predictive (BiPDNP) detector. The adaptation technique can optimize the LDPC decoding performance for each data zone and read head, thereby relaxing the acceptance criteria for hard disk drive read/write heads and disk media, enabling acceptance and use of a much broader range of head and media for hard disk drives.
1. A method for adapting low-density parity-check (LDPC) codes for a hard disk drive system comprising:
selecting a specific zone in a disk media of the hard disk drive system;
defining a normalization factor for decoding LDPC codes, which reduces a variation of bit error rate for different signal-to-noise ratio (SNR) based on known pseudo-random data pattern for the specific zone;
introducing the normalization factor into the LDPC codes for the specific zone; and
repeating the selecting operation, defining operation, and introducing operation for each zone in the disk media of the hard disk drive system.
2. The method in accordance with claim 1 , wherein the introducing operation comprises introducing the normalization factor into a check node of LDPC codes.
3. The method in accordance with claim 1 , wherein the introducing operation comprises introducing the normalization factor into a bit node of LDPC codes.
4. The method in accordance with claim 1 , wherein the introducing operation comprises introducing the normalization factor into the channel log-likelihood ratios (LLR s ).
5. The method in accordance with claim 1 , wherein the LDPC codes are decoded by a sum-product algorithm (SPA) decoder.
6. The method in accordance with claim 1 , wherein the LDPC codes are decoded by a Min-Sum decoder.
7. The method in accordance with claim 1 , wherein the selecting operation, defining operation, introducing operation, and repeating operation are performed during a test stage of manufacturing the hard disk drive system.
8. The method in accordance with claim 1 , wherein the selecting operation, defining operation, introducing operation, and repeating operation are performed during re-reading of manufacturing the hard disk drive system.
9. A method for adapting low-density parity-check (LDPC) codes for hard disk drive system comprising
selecting a read head of each hard disk drive in the hard disk drive systems;
defining a normalization factor for decoding LDPC codes, which reduces a variation of bit error rate for different signal-to-noise ratio (SNR) based on a known pseudo-random data pattern for the read head;
introducing the normalization factor into the LDPC codes for the read head; and
repeating the selecting operation, defining operation, and introducing operation for each read head in the hard disk drive systems.
10. The method in accordance with claim 9 , wherein the introducing operation comprises introducing the normalization factor into a check node of LDPC codes.
11. The method in accordance with claim 9 , wherein the introducing operation comprises introducing the normalization factor into a bit node of LDPC codes.
12. The method in accordance with claim 9 , wherein the introducing operation comprises introducing the normalization factor into the channel log-likelihood ratios (LLR s ).
13. The method in accordance with claim 9 , wherein the LDPC codes are decoded by a sum-product algorithm (SPA) decoder.
14. The method in accordance with claim 9 , wherein the LDPC codes are decoded by a Min-Sum decoder.
15. The method in accordance with claim 9 , wherein the selecting operation, defining operation, introducing operation, and repeating operation are performed during a test stage of manufacturing of the hard disk drive systems.
16. The method in accordance with claim 9 , wherein the selecting operation, defining operation, introducing operation, and repeating operation are performed during re-reading of manufacturing of the hard disk drive systems.