A Turbo Coding System for High Speed

Abstract — This paper presents a new turbo coding scheme for high data rate applications. It uses a special interleaver structure that is naturally suited for parallel processing and a multiple-round early stopping test involving both sign check and a CRC code. A memory (storage) management mechanism is included as a critical part of the decoder. The proposed coding scheme offers new design options and tradeoffs that are not available to conventional convolutional turbo codes (CTCs). In particular, it becomes possible for the decoder to employ an efficient inter-block collaborative decoding algorithm, passing the information obtained from stopping test proved blocks to other unproved blocks. It also becomes important to have a proper decoding schedule. The combined effect is improved performance and reduction in the average decoding latency. We show that the memory manager has a modular-like effect in that additional memory units render enhanced performance due not only to less forced early stopping but to possible increases of the interleaving depth. It also provides additional design tradeoff amongst performance, speed and required memory size. Depending on the decoding schedule, the degree of parallelism and other decoding resources available, the proposed scheme admits a variety of decoder architectures that meet a large range of speed and performance demands. Index Terms — Turbo codes, interleaver, inter-block permuta-tion, parallel decoding, early-stopping