8687

8068

كارشناسي ارشد

رياضي كاربردي

اصفهان: دانشگاه صنعتي اصفهان، دانشكده علوم رياضي

1392

سيزده،141ص.: مصور

ص.ع.به فارسي و انگليسي

رياضي

ID8068

به فارسي و انگليسي: قابل رويت در نسخه ديجيتالي

Windowed Decoding of LDPC Convolutional Codes over Erasure Channels Neda Eslamizadeh n eslamizadeh@math iut ac ir 2014 Department of Mathematical Sciences Isfahan University of Technology Isfahan 84156 83111 Iran Supervisor Prof Morteza Esmaeili emorteza@cc iut ac ir Advisor Dr Mohammad Hessam tadayon mhtadayon@gmail com 2010 MSC 68P 30 94B05 Keywords Low density parity check codes Belief propagation Convolutional codes Decoding thresholds Erasure channels Iterative decoding Stopping sets Windowed decoding Abstract In this thesis a new class of LDPC codes called protograph codes is introduced After introduc ing convolutional codes LDPC codes and LDPC convolution LDPCC codes models that can beobtained by expansion of a protograph are presented Also decoding algorithms including the belief propagation BP algorithm for nite length codes over binary erasure channels are studied and thesealgorithms are extended to algorithms for decoding in nite length LDPC convolution codes One ofthe introduced algorithms is called windowed decoding WD algorithm A windowed decoding schemeexploits the convolutional structure of the parity check matrix of the convolutional codes to decodenonterminated codes while maintains many of the key advantages of iterative decoding schemes likethe BP decoder especially the low complexity and superior performance In this thesis the advantages of this decoding scheme are studied and certain characteristics ofLDPCC code ensembles which a ect the performance of these codes with the windowed decoder areidenti ed The performance of these ensembles and codes are considered over erasure channels withand without memory The structure of LDPCC code ensembles is suitable to obtain a performanceclose to the theoretical limits over the memoryless erasure channel both for the BP decoder andwindowed decoding However the same structure imposes limitations on the performance over erasurechannels with memory

مرتضي اسماعيلي

محمدحسام تدين

حميدرضا مرزبان، علي زاغيان