中文摘要：

提出了利用可分解的可分组设计构造低密度校验码的新方法，所构造的低密度校验码的围长至少为6，且码率、码长灵活可变．同时，基于可分解的可分组设计，又构造了一类掩模矩阵，从而利用掩模技术，得到了更多的准循环低密度校验码．数值结果表明，在加性高斯自噪声信道上，采用和积译码算法，所提出的低密度校验码的性能优异且迭代收敛快．此外，掩模后的准循环低密度校验码比掩模前有较大的误码率／误帧率性能提升．

英文摘要：

A new construction method for low-density parity-check （LDPC） codes is presented based on resolvable group divisible designs （RGDDs）. The resulting LDPC codes are free of 4-cycle. With the use of RGDDs, a class of masking matrices is also constructed, and then many more quasi-cyclic （QC） LDPC codes are obtained by the masking technique. Numerical results show that the proposed LDPC codes with iterative decoding using the sum-product algorithm perform very well over the AWGN channel. Furthermore, the QC-LDPC codes constructed based on masking have a better BER/FER performance than the original ones.