An Improved Construction of LDPC Codes Based on Data Punctured Hybrid ARQ

A data puncturing type-II hybrid automatic retransmission request protocol, using LDPC codes which have the constructions with low encoding complexity and moderate matrix dimensions, is a good tradeoff between the system throughput and the hardware overhead. Based on the characteristics of this protocol that only the parity bits are sent in each retransmission and the puncturing is operated on the information bits, we introduce an improved matrix construction which increases the reliability of parity bits and the decoding performance without any further additional encoding/decoding complexity. There are two iterative decoding steps in the receiver for each retransmission, so we optimize the noise thresholds of both iterative decoding steps and find a more desirable irregular distribution by the density evolution. Simulation results of the data throughput show that the codes with the improved construction and distribution obviously outperform the original codes