Iterative Decoding of Network Coding HARQ in LDPC System

This paper proposes an iterative decoding algorithm for network coding HARQ (NC-HARQ) retransmission scheme in LDPC system. Including two erroneous codewords and one retransmitted network coded word, a larger Tanner graph is applied in the decoding algorithm. We modify the process of iterative decoding and separate the external information into two parts which come from channel coding and network coding respectively. Different iteration numbers are set in these two parts and a weighting factor is multiplied to the latter one. Simulation results show that, compared with traditional HARQ in which the repeat codewords are the erroneous codewords themselves, the proposed scheme can not only reduce the retransmission number but also improve the throughput significantly.