Iterative decoding algorithm and terminating criteria for inter-block permuted turbo codes

Abstract

Inter-block permutation (IBP) concept is a simple but effective technique to improve the performance of a conventional turbo code. On the other hand, proper early termination leads to reduced decoding latency without compromising the performance. For inter-block permuted turbo codes (IBP-TC), however, the termination time variation over blocks within the interleaving span necessitates a new design paradigm. We use both cyclic redundancy check (CRC) code and sign check to make a termination decision and generate soft information for unterminated neighboring blocks at the same time. The new decoder that combines the features of iterative decoding and variable stopping time not only yields less average decoding delay but also outperforms its fixed-stopping-time counterpart by 0.2 - 0.3 dB.