A parallel decoding scheme for turbo codes

The recursive computations in the MAP-based decoding of turbo codes usually introduce a significant amount of decoding delay. In this paper, we present a method for reducing the decoding delay by means of segmenting a block into several sub-blocks, which are partially overlapped. The proposed sub-block segmentation scheme allows for the parallel decoding of each component code by using several sub-block decoders. The number of steps for the recursive computations in each sub-block decoder is reduced to O(N/W), where W is the number of segmented sub-blocks. The decoding delay is approximately one-Wth that of a conventional MAP-based turbo-coding system. The cost paid is a slight degradation in bit error rate performance and a reasonable increase in hardware complexity.