Fast BF Decoder with Column Zone Convergence Detection
A method for operating a BF decoder and an associated memory system utilizing the BF decoder. The method includes a) providing a parity check matrix having column zones with different column weights, b) bit-flip BF decoding read codewords from a memory, the read codewords having errors, and the BF decoding producing decoded codewords with a measured error rate determined with the parity check matrix, and c) upon BF iteration to reduce the measured error rate, skipping column zones of the parity check matrix variables which have shown zone convergence to correct bit values in the decoded codewords.
1 . A method for operating a bit-flip (BF) decoder, comprising:
providing a parity check matrix having column zones with different column weights;
BF decoding read codewords from a memory, the read codewords having errors, and the BF decoding producing decoded codewords with a measured error rate determined with the parity check matrix; and
upon BF iteration to reduce the measured error rate, skipping column zones of the parity check matrix which have shown zone convergence to correct bit values for the decoded codewords.
2 . The method of claim 1 , further comprising detecting the zone convergence by constraining the parity check matrix to have column zones with different column weights and comparing syndrome weights of the column zones as an indicator of the zone convergence.
3 . The method of claim 2 , wherein
the parity check matrix has three bottom-most rows and three different column weights, and
the three bottom-most rows have different regions of all-zero entries.
4 . The method of claim 3 , wherein
a first row of the three bottom-most rows has all non-zero in all columns of the parity check matrix, the columns having high, medium, and low column weights;
a second row of the three bottom-most rows has non-zero entries only in columns of the parity check matrix with the high and medium weights column; and
a third row of the three bottom-most rows has non-zero entries only in columns of the parity check matrix with the high column weight.
5 . The method of claim 1 , further comprising detecting the zone convergence by adding cyclic redundancy bits to the parity check matrix.
6 . The method of claim 5 , wherein
the cyclic redundancy bits comprise bits appended to the parity check matrix for error decoding the read codewords read from the column zones with different column weights.
7 . The method of claim 6 , wherein
the BF decoding decodes the read codewords from the column zones having high, medium, and low column weights.
8 . The method of claim 1 , further comprising detecting the zone convergence by utilizing checksum calculations on the read codewords read from the column zones having different column weights
9 . The method of claim 8 , further comprising determining thresholds for continued BF decoding based on the checksum calculations.
10 . The method of claim 9 , wherein the different column weights comprise high and low column weights.
11 . A memory system comprising:
a memory device; and
a bit-flip (BF) decoder in communication with a storage of the memory device,
wherein the BF decoder is configured to:
provide a parity check matrix having column zones with different column weights,
bit-flip BF decode read codewords from a memory, the read codewords having errors, and the BF decoding producing decoded codewords with a measured error rate determined with the parity check matrix; and
upon BF iteration to reduce the measured error rate, skip process column zones of the parity check matrix variables which have shown zone convergence to correct bit values for the decoded codewords.
12 . The system of claim 11 , wherein the BF decoder is configured to:
detect the zone convergence by constraining the parity check matrix to have column zones with different column weights and comparing syndrome weights of the column zones as an indicator of the zone convergence.
13 . The system of claim 12 , wherein
the parity check matrix has three bottom-most rows and three different column weights, and
the three bottom-most rows have different regions of all-zero entries.
14 . The system of claim 13 , wherein
a first row of the three bottom-most rows has all non-zero in all columns of the parity check matrix, the columns having high, medium, and low column weights;
a second row of the three bottom-most rows has non-zero entries only in columns of the parity check matrix with the high and medium weights column; and
a third row of the three bottom-most rows has non-zero entries only in columns of the parity check matrix with the high column weight.
15 . The system of claim 11 , wherein the BF decoder is configured to:
detect the zone convergence by adding cyclic redundancy bits to the parity check matrix.
16 . The system of claim 15 , wherein
the cyclic redundancy bits comprise bits appended to the parity check matrix for error decoding the read codewords read from the column zones with different column weights.
17 . The system of claim 16 , wherein the BF decoder is configured to:
decode the read codewords from the column zones having high, medium, and low column weights.
18 . The system of claim 11 , wherein the BF decoder is configured to:
detect the zone convergence by utilizing checksum calculations on the read codewords read from the column zones having different column weights
19 . The system of claim 18 , wherein the BF decoder is configured to:
determine thresholds for continued BF decoding based on the checksum calculations.
20 . The system of claim 19 , wherein the different column weights comprise high and low column weights.