Abstract: The demapping algorithm for the systems of hard-decision feedback based Bit-Interleaved Coded Modulation with Iterative Decoding（BICM-ID） calculates simply and has low complexity, so it is prone to be realized. The pre-dicision error bits are excessive in low SNR, so the error codes spread when they are feedback. In allusion to this problem, an improvement iterative demapping algorithm based on hard decision feedback is given, and its complexity to the primary algorithm is compared. Simulation results show that the proposed scheme have better performance both over AWGN and Rayleigh fading channels than the former system.

Key words: Bit-Interleaved Coded Modulation（BICM）, demapping, reliability

摘要： 基于硬判决反馈的比特交织编码调制迭代译码（BICM-ID）系统解映射算法计算简单，复杂度低，易于工程实现，但在信噪比较低时，由于预先判决的错误较多，反馈时容易产生误码传播。针对这一问题，提出了一种改进的基于硬判决反馈的迭代解映射算法，并从复杂度方面与原算法进行了分析对比。仿真结果表明，在AWGN信道、Rayleigh衰落信道下，使用改进算法的BICM-ID系统，性能较原系统得到了有效提高。

关键词: 比特交织编码调制, 解映射, 可靠性