Constrained decoding for turbo-CRC code with high spectral efficient modulation

In this paper, we propose a constrained decoding algorithm for turbo-CRC codes with high spectral efficient modulation. We follow a data structure adopted in 3GPP in which the large data frame used for turbo coding consists of multiple CRC packets. First, we modify the turbo encoder by introducing an additional interleaver to permute correctly decoded bits at early stages of decoding over the entire frame. Then, we propose a constrained decoding algorithm at the receiver, making use of the information of correctly decoded bits to help the decoding of other bits and reduce the complexity. Experimental results demonstrate the excellent performance of the entire system. In addition, the error localization property inherent in the system may benefit other applications such as ARQ.