An Algorithm of the Short Cycle in Check Matrix of LDPC be Eliminated

LDPC code which is near to the Shannon limit is an excellent linear error-correcting code,with the characteristics of easy implementation and low complexity.In the paper the problem of the 0-1 matrix in the LDPC code is to find the best same order loop permutation expansion matrix E,and the appropriately smallest positive integer q,for a given check-matrix H(i.e.0-1matrix) to make all the short cycles(length 4 or less than 6) in check-matrix H be eliminated,where the sum of positive and negative integers in matrix E is not a multiple of q.Finally this algorithm is implemented.