Construction of Quasi-cyclic LDPC Codes Based on Optical Orthogonal Codes

Based on the characteristics of optical orthogonal codes,a new algorithm for constructing quasi-cyclic LDPC codes is proposed.Firstly,based on optical orthogonal codes,we can get an initial matrix which meets the parameter request,then under the proposed formula and the characteristics of quasi-cyclic LDPC codes to determine the shift parameter matrix.Finally,using all-zero matrix and the circlet permutation matrix to fill the shift parameter matrix,we can get a check matrix without cycles with length of 4 and 6.Simulations show that,under the AWGN channel and the BP decoding algorithm,the new quasi-cyclic LDPC codes are better than Mackay's codes in the bit error rate and they are more proper for hardware implementation.