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1、第9期雷菁等:基于PEG算法的準循環(huán)擴展LDPC碼構(gòu)造·111·基于PEG算法的準循環(huán)擴展LDPC碼構(gòu)造雷菁1,王建輝1,2,唐朝京1(1.國防科學(xué)技術(shù)大學(xué)電子科學(xué)與工程學(xué)院,湖南長沙410073;2.中國人民解放軍66018部隊,北京100041)摘要:推導(dǎo)證明了準循環(huán)結(jié)構(gòu)的LDPC碼(low-densityparity-checkcode)一致校驗矩陣與其對應(yīng)Tanner圖環(huán)結(jié)構(gòu)之間的一些重要關(guān)系。在此基礎(chǔ)上提出了一種基于PEG(progressedgegrowth)算法的準循環(huán)擴展LDPC碼構(gòu)造算法,利用PEG算法產(chǎn)生基矩陣,再對基矩陣進行準循環(huán)擴展。該擴展算法可以在不改變基矩陣度分布比
2、例情況下,有效消除基矩陣中的短環(huán)。仿真結(jié)果表明,在碼長相同、碼率和度分布近似情況下,新算法得到的碼在經(jīng)典BP和MS譯碼算法下性能不亞于PEG等方法構(gòu)造的碼。通過對比分析認為,在給定度分布的情況下,優(yōu)化設(shè)計的環(huán)結(jié)構(gòu)可明顯改善譯碼性能,此算法利用準循環(huán)碼環(huán)結(jié)構(gòu)交疊較少特點,較好地實現(xiàn)了編碼復(fù)雜度和譯碼性能之間的統(tǒng)一。關(guān)鍵詞:PEG算法;準循環(huán)擴展;循環(huán)置換矩陣;編碼復(fù)雜度;本地圍長;環(huán)結(jié)構(gòu)中圖分類號:TN911文獻標識碼:B文章編號:1000-436X(2008)09-0103-08Quasi-cyclicextensionbasedonPEGalgorithmforconstructionofL
3、DPCcodesLEIJing1,WANGJian-hui1,2,TANGChao-jing1(1.NationalUniversityofDefenseTechnology,Changsha410073,China;2.Unit66018ofthePLA,Beijing100041,China)Abstract:SeveralimportantrelationsbetweenthecyclestructureontheTannergraphandtheparity-checkmatrixHofLDPCcodeswereproved.AnewalgorithmforconstructingLD
4、PCcodeswasproposedthatintroducedquasi-cyclicextensionmethodtoPEGalgorithm.AfterabasicmatrixwasconstructedwithPEGalgorithm,circulantpermutationmatriceswouldreplacethe“1”sinthebasicmatrix.Thenewmethodcouldeliminateeffectivelytheshortcyclesinthebasicmatrixwithoutchangingthedegreedistributionfractionoft
5、hebasicmatrix.Simulationsshowthatthequasi-cyclicextendedcodesbasedonPEGalgorithmhaveasgooderrorcorrectingperformanceastheLDPCcodesgeneratedbyPEGalgorithminthesameconditionsofcodelength,rate,degreedistributionanddecodingalgorithm.Theconclusionofcontrastiveanalysisisthatwell-chosencyclestructurescanim
6、provethedecodingperformanceobviouslyunderthegivendegreedistribution.Theproposedalgorithmcanofferagoodperformanceandlowencodingcomplexitysynchronouslybytakingadvantageofthequasi-cycliccode’scharacteristicthatitsparity-checkmatrixHhaslesssuperpositionwithinthecycles.Keywords:PEGalgorithm;quasi-cyclice
7、xtension;circulantpermutationmatrix;encodingcomplexity;localgirth;cyclestructure第9期雷菁等:基于PEG算法的準循環(huán)擴展LDPC碼構(gòu)造·111·1引言收稿日期:2008-01-03;修回日期:2008-07-13基金項目:國家自然科學(xué)基金資助項目(60572176)FoundationItem:TheNationalN