简介：Aconstructionmethodbasedonthep-planetodesignhigh-girthquasi-cycliclow-densityparity-check(QC-LDPC)codesisproposed.Firstlythegoodpointsineverylineofthep-planecanbeascertainedthroughfilteringthebadpoints,becausethedesignedparity-checkmatrixesusingthesepointshavetheshortcyclesinTannergraphofcodes.Thenoneofthebestpointsfromtheresidualgoodpointsofeverylineinthep-planewillbefound,respectively.Theoptimalpointisalsosingledoutaccordingtothebiterrorrate(BER)performanceoftheQC-LDPCcodesatlast.ExplicitnecessaryandsufficientconditionsfortheQC-LDPCcodestohavenoshortcyclesarepresentedwhichareinfavorofremovingthebadpointsinthep-plane.Sincepreventingtheshortcyclesalsopreventsthesmallstoppingsets,theproposedconstructionmethodalsoleadstoQC-LDPCcodeswithahigherstoppingdistance.

简介：Inordertomeettheneedsofhigh-speeddevelopmentofopticalcommunicationsystem,aconstructionmethodofquasi-cycliclow-densityparity-check(QC-LDPC)codesbasedonmultiplicativegroupoffinitefieldisproposed.TheTannergraphofparitycheckmatrixofthecodeconstructedbythismethodhasnocycleoflength4,anditcanmakesurethattheobtainedcodecangetagooddistanceproperty.Simulationresultsshowthatwhenthebiterrorrate(BER)is10-6,inthesamesimulationenvironment,thenetcodinggain(NCG)oftheproposedQC-LDPC(3780,3540)codewiththecoderateof93.7%inthispaperisimprovedby2.18dBand1.6dBrespectivelycomparedwiththoseoftheRS(255,239)codeinITU-TG.975andtheLDPC(32640,30592)codeinITU-TG.975.1.Inaddition,theNCGoftheproposedQC-LDPC(3780,3540)codeisrespectively0.2dBand0.4dBhighercomparedwiththoseoftheSG-QC-LDPC(3780,3540)codebasedonthetwodifferentsubgroupsinfinitefieldandtheAS-QC-LDPC(3780,3540)codebasedonthetwoarbitrarysetsofafinitefield.Thus,theproposedQC-LDPC(3780,3540)codeinthispapercanbewellappliedinopticalcommunicationsystems.

简介：鉴于伪周期的低密度的同等值检查(QC-LDPC)的编码复杂性编码的问题，高，最小的距离不足够大它导致错误修正表演的降级，基于完成式，周期的差别设置的新不规则的type-IIQC-LDPC代码(CDS)被构造。这些type-IIQC-LDPC代码的同等值检查矩阵与0的重量由零个矩阵组成，有1的重量的circulant排列矩阵(CPM)和有2的重量(W2CMs)的circulant矩阵。在同等值检查矩阵的W2CMs的介绍使完成能改进错误的更大的最小的距离可能--代码的修正性能。这些代码的更黝黑的图没有girth-4，因此，他们有优秀译码集中特征。另外，因为同等值检查矩阵有伪双的斜结构，快编码算法能有效地减少编码复杂性。新type-IIQC-LDPC编码的模拟结果表演能完成更优秀的错误修正表演并且没在添加剂白人Gaussian噪音(AWGN)上有错误地板现象有和产品算法(矿泉)的隧道反复的译码。