一种高围长低复杂度LDPC码构造方法

LDPC Codes Construction with High Girth Low Complexity

LDPC(低密度奇偶校验)码常见的编码方法常常无法将校验矩阵的围长和线性无关相统一,对编译码复杂度和译码性能有一定影响。文章提出了一种低复杂度LDPC的构造方法,通过构造分块矩阵A和B,获得一个围长为10、列重为2、具有近似下三角形式的校验矩阵,且矩阵各行之间线性无关。该码具有以下优点:较高的围长能提升译码性能;较低的列重使该码适合在部分响应信道传播;近似下三角形式和线性无关的特性,较好地降低了编译码的复杂度。采用Matlab软件的仿真结果表明,在高斯白噪声信道、BP(置信传播)译码算法下,该码比普通的10围长LDPC码具有更低的复杂度,比普通的6围长LDPC码具有更好的译码性能。

The conventional encoding method of Low Density Parity Check （LDPC）Code often cannot put the girth and nonsin-gularity of check matrices into consideration at the same time,which has negative effects on the performances of encoding and decoding,and increases the decoding complexity.A low complexity method to construct check matrices is presented.A matrix with properties of girth of 10,column weight of 2,nonsingularity,and approximate lower triangular is generated by construc-ting the sub-matrix A and sub-matrix B step by step.Due to these features,some advantages such as better decoding perform-ance,more suitable for partial response channels,lower encoding and decoding complexity are shown.The simulation result shows that the proposed coding scheme has lower complexity than the code with girth of 10.It also presents better decoding performance than common code with girth of 6 in AWGN channels after Belief Propagation（BP）decoding algorithm.