A modified adaptive hybrid FEC/ARQ protocol using turbo codes with incremental redundancy transmission

In a wireless environment, an FEC or ARQ scheme may be insufficient to achieve the desired performance due to the time-varying nature of the channel. In this paper, we propose a modified adaptive hybrid FEC/ARQ scheme using turbo codes with incremental redundancy. If retransmission is requested, information bits with magnitude of log-likelihood values smaller than the threshold are retransmitted together with the extra parities. In the iterative decoding of packets with extra parities, the decoder is designed to utilize the soft outputs generated from the previous decoding process. Simulation results reveal that the proposed scheme outperforms the traditional schemes under different channel conditions.