An Ordered HARQ Scheme for LDPC-Coded OFDM System

In this paper, an ordered Hybrid ARQ(HARQ) scheme for LDPC-coded OFDM system is presented , in which the important bits with large degrees have high retransmission priorities and are mapped to the sub-carriers with better CQI levers in OFDM system. The new scheme considers the degree distribution property of LDPC codes and improved the system performance by providing the important bits with more protection. The performance of the new scheme has been investigated by the Gaussian Approximation (GA). The analysis and simulation results prove that the new scheme is practical because it has better performance with low system complexity.