An Improved Degree Distribution Based HARQ for LDPC

An improved hybrid ARQ (HARQ) scheme for irregular LDPC codes based on degree distributions is introduced in this paper. In traditional degree distribution based HARQ (DDB-HARQ), the source selectively retransmits the nodes with large degrees and this scheme brings a significant gain to the irregular LDPC coded system. However, the selecting method of the traditional scheme is thought to be not accurate enough. In this paper, an improved method in which the source retransmits the nodes in different degrees at specific proportions each time has been proposed. According to the analysis with Gaussian approximation (GA) the improved scheme could be more efficient since the retransmission proportions are more accurate which has also been proved by the simulation results