基于多用户度分布优化的LDPC码构造方案  

LDPC code construction scheme based on multi-user degree distribution optimization

作　　者：关梦生 朱敏[1] 白宝明[1] 刘彤[1] GUAN Mengsheng;ZHU Min;BAI Baoming;LIU Tong(State Key Laboratory of Integrated Services Networks,Xidian University,Xi’an 710071,China)

机构地区：[1]西安电子科技大学空天地一体化综合业务网全国重点实验室,陕西西安710071

出　　处：《通信学报》2025年第2期72-82,共11页Journal on Communications

基　　金：国家自然科学基金资助项目(No.62271380,No.62171356)。

摘　　要：为了在多用户相关源情况下设计具有优秀性能的低密度校验(LDPC)码,参考点对点信道中LDPC码的度分布优化算法,将其推广到多用户领域,并基于此设计了一套码构造方案。首先从多用户联合译码因子图出发推导了迭代更新信息的概率密度函数和外部信息转移函数;然后以最大化用户和速率为目标,外部信息译码收敛为条件,设计出适用于不同多用户场景下的数学优化模型,获得度分布参数;最后以该参数为基础,结合代数循环移位值、环分布、最小距离等矩阵优化方案,设计了代数构造准循环LDPC码的流程。为验证方案有效性,在不同场景下使用构造码字与现有的几种多用户构造码字进行对比。仿真结果表明,构造的单一速率LDPC具有明显的性能优势,在此基础上扩展得到的速率兼容LDPC(RC-LDPC)码在一定码率区间内优于现有方案的同时,也能较好地趋近单一速率构造的性能水平。To design low-density parity-check(LDPC)codes with excellent performance in the multi-user related source scenario,the degree distribution optimization algorithm for LDPC codes in point-to-point channels was extended to the multi-user scenario,and based on this,a set of code construction schemes was developed.First,the iterative update information probability density function and external information transfer function were derived from the multi-user joint decoding factor graph.Then,the mathematical optimization model was designed with the maximization of sum rate as the goal and the external information decoding convergence as the condition,the degree distribution parameters were obtained.Subsequently,based on these parameters and incorporating matrix optimization schemes such as algebraic cyclic shift values,cycle distribution,and minimum distance,a process for algebraically constructing quasi-cyclic LDPC codes was designed.To validate the effectiveness of the proposed scheme,the constructed codes were compared with existing multi-user constructed results across various scenarios.Simulation results show that the single-rate LDPC code has significant performance advantages,and the rate compatible LPDC(RC-LPDC)code extended from this framework not only outperforms existing schemes within a specific code rate range but also closely approaches the performance level of the single-rate construction.

关 键 词：多用户度分布 准循环 速率兼容 低密度校验码 

分 类 号：TN92[电子电信—通信与信息系统]