系统LT码在删除信道下的渐进性能分析及度分布设计  

Asymptotic Performance Analysis and Degree Distribution Design for Systematic Luby Transform Codes over Binary Erasure Channel

作　　者：华洁[1,2] 徐大专[1,2] 许生凯[1,2] 

机构地区：[1]南京航空航天大学江苏省物联网和控制技术重点实验室,南京211106 [2]南京航空航天大学电子信息工程学院,南京211106

出　　处：《数据采集与处理》2017年第5期906-912,共7页Journal of Data Acquisition and Processing

基　　金：国家自然科学基金(61471192;61371169)资助项目;江苏省普通高校研究生科研创新计划(SJLX15_0120)资助项目;中央高校基本科研业务费专项资金资助项目

摘　　要：首先基于与或树分析法,对系统LT码在删除信道下的渐进性能公式进行推导,并给出其下限。仿真结果表明当开销足够大时,实际误码率,渐进性能与下限三者完美匹配。然后根据渐进性能,提出改进的优化模型(Improved systematic linear programming,ISLP)对度分布进行优化设计。优化所得的度分布明显优于鲁棒孤波分布(Robust soliton distribution,RSD)分布与截断度分布(Truncated degree distribution,TDD)分布。另外,优化后的度分布其渐进性能可由设定的开销与误码率进行控制,即在所设置的开销之内达到理想的误码率,这一特性可进一步影响完全译码时所需开销。仿真结果表明,数据恢复时所需的开销与所设置的开销相近。对比系统LT码和LT码的误码率与恢复原始数据时所需的开销和编译码时间,表明系统LT码能比LT码更快地恢复原始数据,具有更优的性能。The asymptotic performance formula of systematic LT codes(SLT)in binary erasure channel(BEC)is firstly derived based on AND-OR tree analysis and its lower limit is given.Simulation results show that the actual bit error ratio(BER),the asymptotic performance and the lower limit match each other perfectly when the overhead is large enough.Then the optimization of degree distribution is proposed by the improved systematic linear programming(ISLP)model in accordance with the asymptotic performance.The optimized degree distribution is obviously superior to robust soliton distribution(RSD)and truncated degree distribution(TDD).Furthermore,the asymptotic behavior of the optimized degree distribution can be controlled by the given overhead and BER.In other words,the ideal BER can be obtained within the overhead we want,which also influences the overhead for complete decoding.Simulation results show that the overhead required for data recovery is close to that of we set.The comparison of BER,the overhead required for data recovery and the time of encoding and decoding for LT codes and SLT codes show that SLT codes have better performance than LT codes with more quick speed in data recovery.

关 键 词：渐进性能 度分布 线性优化 系统LT码 

分 类 号：TN929.5[电子电信—通信与信息系统]