A parallel MAP decoding scheme for turbo codes

[[abstract]]© 2001 中國電機工程學會 - The recursive computations in the maximum a posteriori probability (MAP) based decoding of turbo codes usually introduce a significant amount of decoding delay. We present a method for reducing the decoding delay that is based on segmenting a block of data into several sub-blocks that are partially overlapped. The proposed sub-block segmentation scheme allows parallel decoding of each component code of a turbo code by using several sub-block decoders working in parallel. The number of steps for the recursive computations in each sub-block decoder is reduced from O(N) to O(N/W), where N is the block length and W is the number of sub-blocks. Owing to parallel decoding, the decoding delay is only 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[[department]]電機工程學