Luo et al wrote in a recent paper [A Fast Algorithm for Computing gcd Based on Binary Multi Precision,this journal,2002,Vol.32,No.5,pp.542 545; MR 2003h:11161 ] that “the classical Euclid’s algorithm for computing t...Luo et al wrote in a recent paper [A Fast Algorithm for Computing gcd Based on Binary Multi Precision,this journal,2002,Vol.32,No.5,pp.542 545; MR 2003h:11161 ] that “the classical Euclid’s algorithm for computing the gcd of two integers takes time O(\%ln\% 3N)”, and “present” an improved algorithm (called “binary gcd” for short) based on binary multi precision with time complexity O(\%ln\% 2N). In this paper,we point out two well known facts: firstly,the binary gcd,without usefull implimentation improvements, is identical in mathematical theory to Stein’s Binary GCD algorithm published in 1967; secondly,both Euclid’s algorithm and Binary GCD have the same time complexity O(\%ln\% 2N).展开更多
准循环重复累积(Quasi⁃Cyclic Repeat Accumulate,QC⁃RA)码具有准循环低密度奇偶校验(Low Density Parity Check,LDPC)码的优点,同时能实现差分编码且为系统码,非常适用于编码协作系统,文中研究采用QC⁃RA码的编码协作系统。首先,提出基...准循环重复累积(Quasi⁃Cyclic Repeat Accumulate,QC⁃RA)码具有准循环低密度奇偶校验(Low Density Parity Check,LDPC)码的优点,同时能实现差分编码且为系统码,非常适用于编码协作系统,文中研究采用QC⁃RA码的编码协作系统。首先,提出基于最大公约数(Greatest Common Divisor,GCD)定理的QC⁃RA码构造方法;然后,进一步基于GCD定理联合构造编码协作系统信源节点与中继节点采用的QC⁃RA码,并从理论上证明基于该联合构造方法得到的编码协作系统QC⁃RA码无girth⁃4、girth⁃6环。仿真结果表明,采用QC⁃RA码的编码协作系统相对于点对点系统具有明显的性能增益;同时,与采用大列重构造QC⁃RA的编码协作相比,采用文中基于GCD定理联合构造的QC⁃RA码的编码协作误码率性能更加优异。展开更多
文摘Luo et al wrote in a recent paper [A Fast Algorithm for Computing gcd Based on Binary Multi Precision,this journal,2002,Vol.32,No.5,pp.542 545; MR 2003h:11161 ] that “the classical Euclid’s algorithm for computing the gcd of two integers takes time O(\%ln\% 3N)”, and “present” an improved algorithm (called “binary gcd” for short) based on binary multi precision with time complexity O(\%ln\% 2N). In this paper,we point out two well known facts: firstly,the binary gcd,without usefull implimentation improvements, is identical in mathematical theory to Stein’s Binary GCD algorithm published in 1967; secondly,both Euclid’s algorithm and Binary GCD have the same time complexity O(\%ln\% 2N).
文摘准循环重复累积(Quasi⁃Cyclic Repeat Accumulate,QC⁃RA)码具有准循环低密度奇偶校验(Low Density Parity Check,LDPC)码的优点,同时能实现差分编码且为系统码,非常适用于编码协作系统,文中研究采用QC⁃RA码的编码协作系统。首先,提出基于最大公约数(Greatest Common Divisor,GCD)定理的QC⁃RA码构造方法;然后,进一步基于GCD定理联合构造编码协作系统信源节点与中继节点采用的QC⁃RA码,并从理论上证明基于该联合构造方法得到的编码协作系统QC⁃RA码无girth⁃4、girth⁃6环。仿真结果表明,采用QC⁃RA码的编码协作系统相对于点对点系统具有明显的性能增益;同时,与采用大列重构造QC⁃RA的编码协作相比,采用文中基于GCD定理联合构造的QC⁃RA码的编码协作误码率性能更加优异。
