基于后验概率的低密度奇偶校验码逆向识别方法研究.pdf

北京大学学报(自然科学版) 第 52 卷 第 3 期 2016 年 5 月 Acta Scientiarum Naturalium Universitatis Pekinensis, Vol. 52, No. 3 (May 2016) doi: 10.13209/j.0479-8023.2016.055 基于后验概率的低密度奇偶校验码 逆向识别方法研究 † 刘婉月 包昕 王达 金野 北京大学信息科学技术学院 , 卫星与无线通信实验室 , 北京 100871; † 通信作者 , E-mail: wangda_2014@126.com 摘要 提出一种基于后验概率对数似然比 (LLR)均值的逆向识别低密度奇偶校验码 (LDPC)校验矩阵的方 法。通过估计接收码字的信道增益以及信道噪声方差值, 得到后验概率对数似然比, 并依据后验概率对数似 然比均值最大化原则, 成功实现对 LDPC 码校验矩阵的逆向识别。仿真结果表明 , 在加性高斯白噪声信道条 件下, 利用所提出的 LDPC 码逆向识别技术, 接收方可准确无误地找到发送方使用的 LDPC 码校验矩阵。 关键词 低密度奇偶校验码(LDPC); 逆向识别 ; 后验概率对数似然比(LLR) 中图分类号 TN911 Research on Low Density Parity Check Code Reverse Recognition Methods Based on Posterior Probability † LIU Wanyue, BAO Xin, WANG Da , JIN Ye Satellite and Wireless Communication Laboratory, School of Electronics and Computer Science, Peking University, Beijing 100871; † Corresponding author, E-mail: wangda_2014@126.com Abstract This paper presents a method of the reverse recognition of the check matrix coded by low density parity check code (LDPC), which is based on the posterior probability log likelihood ration (LLR). The posterior probability LLR was obtained by estimating the channel amplification and the variance of the noise in the received code. A reverse recognition of LDPC code check matrix was achieved following the LLR mean value maximization principle. Simulation results show that the receiver can precisely retrieve the LDPC check code used by the sender under different channel c