Abstract: This paper constructs Partially Balanced Incomplete Block Designs（PBIBD） based on finite fields，and uses them to construct regular Low-Density Parity-Check（LDPC） codes.The constructed LDPC codes are free of 4-cycles and with high flexibility for the choosing of the code rate.Further，the paper even constructs QC-LDPC codes with girth at least 8，they can also be quasi-cyclic.Simulation results show that some of the codes can have slightly better performance than random regular LDPC codes over AWGN channel.

摘要： 通过构造部分平衡不完全区组设计，得到一类低密度校验（LDPC）码，其最小环长（girth）至少为6，码率的选取具有很大的灵活性，而且可以具有准循环结构，进一步，也利用其构造了girth至少为8的准循环LDPC码。计算机仿真结果表明，在加性高斯白噪声信道中与随机码相比，我们构造的一些码具有稍好的译码性能。