Encoding method to QC code

1. A data encoding and/or decoding method executed by a system controlled by a microprocessor which uses a self-orthogonal Quasi Cyclic (QC) code whose parity check matrix is expressed by at least one circulant matrix, wherein a code sequence is generated which satisfies a check matrix, said check matrix being designed in which a column weight w of each circulant matrix is three or larger and a minimum hamming distance of the code is w+2 or larger, and

wherein a period of the QC code is p and a number of rows of the check matrix is m, and one permutation of each element of a j′th (0≦j≦w) address set among w+1 number of address sets redundantly extracted from p number of addresses has w as the number of elements, the circulant matrices that constitute the check matrix is b 0 , j,b 1 , j, . . . , b w−1 , j, and a relationship of b j−1,0 −b i−1,0 +b 0, i −b j−1, i +b i , j−b 0 , j≠0 (mod m) exists where [ij] have values within a range of 2≦j≦w and 1≦i<j.

2. The method according to claim 1 , wherein p is 2 or more.

3. The method according to claim 2 , wherein w is three and the minimum hamming distance of the code is six or larger.

4. The method according claim 2 , wherein w is four or more.

5. The method according to claim 1 , wherein a number of six-cycles included in each circulant matrix of the parity check matrix is minimized.

6. The method according to claim 5 , wherein one of the p number of address sets is {a 0 , a 1 , . . . , a w−1 } where a 0 =0, a relationship of a i0 −a i1 +a i2 −a i3 +a i4 −a i5 ≠0 (mod m) is established for all of the p number of address sets about all of integers of i 0 , . . . , i 1 , i 2 , i 3 , i 4 , and i 5 within a range given by: 1≦i 0 <w; 0≦i 1 <i 0 ; 0≦i 2 ≦i 0 (i 2 ≠i 1 ); 0≦i 3 ≦i 1 (i 3 ≠i 2 ); 0≦i 4 ≦i 2 (i 4 ≠{i 1 , i 3 }); and 0≦i 5 ≦i 3 (i 5 ≠{i 2 , i 4 }).

7. The method according to claim 6 , wherein there is no six-cycle over any of two and three circulant matrices arbitrarily extracted from the plurality of circulant matrices that constitute the parity check matrix.

8. The method according to claim 7 , wherein when one permutation of each element of the j′th (0≦j≦2) address set among three address sets extracted up-to-twice-redundantly from the p number of addresses is supposed to be b 0 , j, b 1 , j, . . . , b w−1 , j, and if a relationship of b 1,0 −b 0 +b 0, 1 −b 1 , 1+b 1, 2 −b 0 , 2≠0 (mod m) is evaluated for all permutations of b 0 , j, b 1 , j, . . . , b w−1 , j, the number of the permutations that do not satisfy the relationship is minimized.

9. The method according to claim 8 , wherein the number of the permutations that do not satisfy the relationship of b 1,0 −b 0,0 +b 0, 1 −b 1 , 1+b 1, 2 −b 0 ,2≠0 (mod m) is zero.

10. The method according to claim 6 , wherein the number of the six-cycles over any of two and three circulant matrices arbitrarily extracted from the plurality of circulant matrices that constitute the parity check matrix is minimized for given values of w, m, and p.

11. The method according to claim 10 , wherein when one permutation of each element of the j′th (0≦j≦2) address set among three address sets extracted up-to-twice-redundantly from the p number of addresses is supposed to be b 0 , j, b 1 , j, . . . , b w−1 , j and if a relationship of b 1,0 −b 0,0 +b 0, 1 −b 1 , 1+b 1, 2 −b 0 , 2≠0 (mod m) is evaluated for all permutations of b 0 , j, b 1 , j, . . . , b w−1 , j, the number of the permutations that do not satisfy the relationship is minimized.

12. The method according to claim 11 , wherein the number of the permutations that do not satisfy the relationship of b 1,0 −b 0,0 +b 0, 1 −b 1 , 1+b 1, 2 −b 0 , 2≠0 (mod m) is zero.