空间耦合LT码的性能研究

Performance research of spatially coupled LT codes

空间耦合LT码是将空间耦合概念用于LT码的一种新型信道编码技术,因其良好的性能被广泛研究。介绍了空间耦合LT码的编码过程,利用密度演进算法研究了其在信息位无限长时的渐进性能,并且比较了空间耦合LT码在规则度分布与不规则度分布下的译码错误率和译码复杂度。同时在有限信息位长度下针对两种度分布进行大量仿真,分析并比较了两者的性能。结果表明:信息位越多,空间耦合LT码越能在低开销时获得低译码错误率,以更快的速度接近渐近性能,在译码错误率相差无几的情况下,使用不规则度分布的空间耦合LT码比使用规则度分布有更快的译码速度,而且在有限信息位长度时译码错误率性能更好,能以更快的速度接近渐近性能。

Spatially coupled LT（Luby Transform） codes, which introduced the concept of spatial coupling into LT codes, were a new type of channel coding technology. They had been widely studied because of their good performance. This paper introduced the encoding process of spatially coupled LT codes, studied the asymptotic performance of LT codes by density evolution, and compared decoding error probability and complexity of spatial coupling LT codes under regular distribution and irregular distribution. What＇s more, a plenty of simulation aimed at these two kinds of degree distribution had been done in this paper under the limited length, and analyzed and compared their performance in many aspects. The results showed that the more information bits, the lower decoding error probability when spatially coupled LT codes had low overhead, and the faster speed to approach to asymptotic perfor- mance. When used regularity and irregularity had little difference in decoding error probability, irregularity could be exploited to have better finite length performance and faster decoding speed for spatially coupled LT codes.