later in 1990's they were rediscovered and soon became the focus in channel code fields because of their remarkable performance close to shannon limit with iterative decoding and their structures for parallel decoding 90年代中后期的重新研究发现,它采用迭代译码算法时表现出接近香农限的优异性能,且译码算法可以并行操作,因此迅速成为近年来通信编码领域的研究热点。