An efficient LDPC encoding scheme for CMMB based on improved LU decomposition

Low-density parity-check (LDPC) codes are widely applied in modern communication system for its capability of approaching channel capacity at low complexity. We design an efficient encoding scheme based on LU decomposition for China mobile multimedia broadcasting (CMMB). We search for element with lightest row-multiplying-column weight from the k th row and k th column, and exchange it with diagonal element of k th row. Then we operate Gaussian elimination to generate triangular matrices. We improve classic LU decomposition by performing both row and column permutations to obtain triangular matrices with lower density and demonstrate procedure of the improved algorithm. Encoding complexity of the proposed method is linear in codeword length with small coefficient. We show that the proposed method can significantly reduce computing operation and cost no extra hardware.