中文摘要：

该文基于由QC-LDPC码获得时不变LDPC卷积码的环同构方法，设计了用有限域上元素直接获得时不变LDPC卷积码多项式矩阵的新算法。以MDS卷积码为例，给出了一个具体的构造过程。所提构造算法可确保所获得的时不变LDPC卷积码具有快速编码特性、最大可达编码记忆以及设计码率。基于滑动窗口的BP译码算法在AWGN信道上的仿真结果表明，该码具有较低的误码平台和较好的纠错性能。

英文摘要：

In this paper, a new ensemble of the polynomial matrix of a time-invariant LDPC convolutional code is proposed. Based on the method of deriving time-invariant LDPC convolutional codes from QC （Quasi-Cyclic）- LDPC block codes, the elements over finite fields are used to generate directly the polynomial parity-check matrices of LDPC convolutional codes. A concrete example of using MDS （Maximum-Distance Separable） convolutional codes to derive the polynomial matrices is given. The proposed method ensures the fast encoding property, maximum encoding memory and designed rate. Simulation results show that the proposed LDPC convolutional codes exhibit low error floor and good decoding performance under BP （Belief Propagation） decoding algorithm over AWGN （Additive White Gaussian Noise） channel.