一种基于16QAM调制系统的LDPC改进算法  

Improved LDPC Algorithm Based on 16QAM Modulation System

作　　者：邓洪高[1] 黄宇仁[1] 孙少帅[1] 

机构地区：[1]桂林电子科技大学,广西桂林541004

出　　处：《电视技术》2012年第11期88-89,92,共3页Video Engineering

基　　金：国家自然科学基金项目(61167006;61172055);广西无线宽带通信与信号处理重点实验室基金项目(11102)

摘　　要：对QAM调制系统进行分析,提出了一种简化状态软输入软输出APP算法。它基于LDPC和积算法思想,与其他简化状态SISO算法相比,具有更为一般的形式。该算法在解调输出时有效利用映射点之间的欧氏距离,计算出每一个编码比特的似然值,从而简化运算复杂度,并且利用判决反馈减小简化状态网格的Euclid距离损失。仿真表明,该方案能够有效利用QAM解调中的软输出,在高斯信道下,简化的译码算法比原有LDPC方案提高了0.25 dB增益。In this paper, QAM Modulation system is analyzed and a reduced state Soft Input Soft Output （SISO） posteriori probability algorithm is pro- posed. Based on the sum-product algorithm, it has the more general form compared with other reduced state SISO algorithms. The proposed algorithm use the Euclidean distance between points to calculate bit likelihood values in the demodulator. Then the likelihood value will be entered into the soft- input decoder, thus leads to the computation complexity reduction. Analysis and simulation result show that the proposed scheme can effectively use the soft-output of QAM demodulation,and can get 0.25 dB gain in Gaussian channel compare to the original scheme.

关 键 词：LDPC 软输入软输出 QAM Euclid距离 

分 类 号：TN919.8[电子电信—通信与信息系统]