Quasi-cyclic Ldpc Codes And Encoding And Decoding Methods

Quasi-cyclic Low Density Parity Check(QC-LDPC) codes is a Shannonlimit-approaching linear block codes.It has lower bit error rate than other linear block codes and convolve codes over Gaussian noise channel,also it has good structures for ASIC implementation.QC-LDPC codes has a good application foreground in digital communications domain.In this paper,the background,purpose and meaning of research QC-LDPC codes are introduced briefly.The basic background of QC-LDPC codes and the limitation of constructing,encoding and decoding QC-LDPC codes are expounded.Then,the constructing method of QC-LDPC codes' parity check matrix is analyzed in detail,a novel block-filling approach to constructing is proposed.The analytical results and simulations show that the construction complexity of the proposed method is much smaller than that of the Cycle-Elimination method.Based on the parity check matrices constructed,how to encode with these matrices is expounded.A novel Block Gauss Elimination(BGE) approach to construction of the generator matrix of QC-LDPC codes is proposed to reduce the dimension of the matrix to be inversed.Analysis and simulation results show that the present approach not only decreases the memory requirement but also reduces the computation complexity.A discussion is put on the encoding implementation using the quasi cyclic generator matrix.Finally,Analysis and simulation on the QC-LDPC decoding implementation are given.Many valuable results are obtained in the experiment,which establish important basis for future research of QC-LDPC codes decoding implementation.