CONCEPTION DE CODES LDPC ET APPAREIL DE CODAGE PERMETTANT LE RÉGLAGE DU DÉBIT DE CODES ET DE LA LONGUEUR DE CODE

摘要

A novel design of families of LDPC codes, methods and apparatus for encoding codeword lengths of variable sizes and different transmission rates are described. The design of LDPC codes is based on two successive decompositions of rectangular blocks of the parity check matrix into underlying rectangular blocks defining three different sizes of blocks q then v and w. The codeword length is variable through divisions by a factor of 2 of the size v while size w is maintained constant. Each rectangular block is assigned with an allocation of its non-zero underlying rectangular blocks corresponding to a circulant matrix of cyclic permutation of diagonal or anti-diagonal matrix. Part of the parity check matrix is constraint to specific cyclic permutations of its rectangular blocks. Different transmission rates can be supported through a specific methodology for the elimination of q blocks from sub-matrices of the parity check matrix and their recombination. Encoding processing steps that involve sub-matrices that can be represented by circulant matrices of circular permutations of diagonal and anti-diagonal matrices is performed in parallel for several blocks of size q. Parallel encoding of blocks of size v is also carried out for each block of size q depending on the codeword length.