截断卷积码的重量枚举函数的计算

针对Turbo码和串行级联卷积码的好码搜索,提出了一种栅格合并方案实现卷积码的码重分布统计.该方案以起始的局部栅格经编码后所得的码重分布为基础,按照把栅格路径长度每次增加为原来的2倍的频率对栅格进行迭代合并,最终得到相应的全局码重分布.与传统的利用状态转移图计算卷积码的码重分布的方法相比,这种栅格合并方案在中、低交织时延下与传统方法的计算复杂度相当,但是省去了大量的预备工作,具有一定的实用意义.

Calculation of the Weight Enumeration Function of Truncated Convolutional Code

Aimed at the searching for good codes in the Turbo code and serially concatenated convolutional code, the paper proposes a novel trellis unity project to calculate the weight distribution of convolutional code. Based on the weight distribution produced by encoding operation in the forepart of trellis, the new project makes iterative trellis unity by doubling previous trellis path length every time to get the whole weight distribution. Under a middle or low interleaving delay, the trellis unity project has a similar calculation complexity with the conventional method which needs to utilize state transference figure. But the new project can omit much preparative calculation work, so it is of significance for practical work.