APPLICATION OF BEAM SEARCH FOR THE DECODING OF ONE CLASS OF LDPC CODES  

作　　者：Li Guangwen Feng Guangzeng 

机构地区：[1]School of Telecommunications and Information Engineering, Nanjing University of Posts and Telecommunications, Nanjing 210003, China

出　　处：《Journal of Electronics(China)》2008年第4期457-464,共8页电子科学学刊（英文版）

基　　金：the National Science Foundation of China(No.60472104).

摘　　要：For one class of Low-Density Parity-Check(LDPC)codes with low row weight in theirparity check matrix,a new Syndrome Decoding(SD)based on the heuristic Beam Search(BS),labeledas SD-BS,is put forward to improve the error performance.First,two observations are made andverified by simulation results.One is that in the SNR region of interest,the hard-decision on thecorrupted sequence yields only a handful of erroneous bits.The other is that the true error pattern forthe nonzero syndrome has a high probability to survive the competition in the BS,provided sufficientbeam width.Bearing these two points in mind,the decoding of LDPC codes is transformed into seekingan error pattern with the known decoding syndrome.Secondly,the effectiveness of SD-BS dependsclosely on how to evaluate the bit reliability.Enlightened by a bit-flipping definition in the existingliterature,a new metric is employed in the proposed SD-BS.The strength of SD-BS is demonstrated viaapplying it on the corrupted sequences directly and the decoding failures of the Belief Propagation(BP),respectively.For one class of Low-Density Parity-Check（LDPC）codes with low row weight in their parity check matrix,a new Syndrome Decoding（SD）based on the heuristic Beam Search（BS）,labeled as SD-BS,is put forward to improve the error performance.First,two observations are made and verified by simulation results.One is that in the SNR region of interest,the hard-decision on the corrupted sequence yields only a handful of erroneous bits.The other is that the true error pattern for the nonzero syndrome has a high probability to survive the competition in the BS,provided sufficient beam width.Bearing these two points in mind,the decoding of LDPC codes is transformed into seeking an error pattern with the known decoding syndrome.Secondly,the effectiveness of SD-BS depends closely on how to evaluate the bit reliability.Enlightened by a bit-flipping definition in the existing literature,a new metric is employed in the proposed SD-BS.The strength of SD-BS is demonstrated via applying it on the corrupted sequences directly and the decoding failures of the Belief Propagation（BP）,respectively.

关 键 词：Low-Density Parity-Check （LDPC） codes Belief Propagation （BP） Beam Search （BS） Error pattern Pyndrome 

分 类 号：TN911.22[电子电信—通信与信息系统]