卫星通信系统中可变码率LDPC码设计方法  

Variable-Rate Low-Density Check Codes for Satellite Communication System

作　　者：马琦[1] 蓝兴[2] 陈曾平[1] 

机构地区：[1]国防科技大学ATR实验室,湖南长沙410073 [2]国防科技大学电子科学与工程学院,湖南长沙410073

出　　处：《信号处理》2009年第5期729-734,共6页Journal of Signal Processing

基　　金：总装备部创新基金(6130524;7130524)

摘　　要：提出了一种基于准循环置换扩展的卫星通信系统可变码率LDPC码设计方法。分析了卫星通信信道的Loo模型及莱斯分布简化模型以计算置信传播解码算法中反映信道特征的初始消息密度,然后使用离散密度进化和粒子群优化在莱斯信道下搜索有较高噪声门限的度分布对,接着利用PEG方法构造具有双对角线结构、围长大于4的基本矩阵,从而确保构造的LDPC码性能较高,最后通过准循环置换扩展基本矩阵得到了多种码率的LDPC码。仿真结果表明,在中低度遮蔽情况下莱斯分布简化模型能很好地近似Loo模型,设计的LDPC码具有线性的编码复杂度,易于工程实现,且性能优良。A design technique of variable-rate low-density parity-check code based on quasi-cyclic extension is proposed for satel- lite communication system. Loo model of satellite communication channel and its＇ simplified edition - Rician distribution model are ana- lyzed. Discrete density evolution and particle swarm optimization are used to search good degree distribution pairs for Rician channels. A basic matrix is constructed with two restricts ： bi-diagonal structure and free of 4-cycle. With quasi-cyclic extension, a group of variable- rate LDPC codes can be constructed from the basic matrix. Simulation results show that Rician distribution model is very close to Loo model in condition of light to medium shadowing,the LDPC codes we presented have linear coding complexity,which can be implemented easily and have good performance.

关 键 词：非规则低密度校验码 度分布 卫星通信 

分 类 号：TN911.22[电子电信—通信与信息系统]