Abstract: For the detected error words by the LDPC decoder, the characteristics of code bits reliability information is investigated. An efficient novel hybrid automatic repeat request (HARQ) scheme is proposed for system coded with Low-Density Parity Check (LDPC) codes. Compared with the Reliability-based hybrid ARQ (RB-HARQ), the new HARQ scheme outperforms the RB-HARQ in consideration of the bit transmission power for the requesting messages in the backward transmission channel. Simulation results show that the new H-ARQ scheme is more practical than RB-HARQ.

Key words: low-density parity-check codes, hybrid automatic repeat request (HARQ), reliability

摘要： 分析了低密度校验(LDPC)码译码所产生的错误码字中码位的译码输出量可靠度信息的统计特性。结合自动重传请求(ARQ)协议提出了一种简单高效的混合ARQ方案，和基于译码可靠度的混合ARQ方案（RB-HARQ）的性能进行了比较。仿真结果说明，在考虑反向信道重传请求消息信息比特功率的条件下，混合ARQ方案的总体性能超过RB-HARQ方案，具有较强的实际应用价值。

关键词: 低密度校验码, 混合自动重传请求, 可靠度