分解法求Turbo码的低码重分布

Decomposition method to calculate the distribution of low-weight codewords of Turbo codes

基于重2自结尾序列的概念,将输入序列分解,分别求出对应的Turbo码低码重分布的各个分量,并讨论了它们对低码重分布的影响。仿真显示,在有些情况下,不仅重2自结尾序列对低码重分布有重要的影响,重2自结尾序列的组合对低码重分布也有着重要的影响。这种分解算法简单灵活,特别有利于Turbo码的结构性能分析及产生稀疏低码重分布的交织器设计。

Based on the concept of weight 2 self-terminating sequence, a new method, called decomposition method, is presented. It decomposes the self-terminating sequence to several sorts, and for every tort, the according components of the low weight distribution is calculated. It shows that in some circumstances, not only the weight 2 self-terminating sequence, but also the compounds of the weight 2 self-terminating sequence have significant affections on the low weight distribution. This method has comparatively less computing complexity and is flexible to realize. It would be very useful to analyze the constructions of the low weight distributions of Turbo codes and to construct an interleaver that can produce a sparse distribution of low weights of Turbo codes by the method.