Abstract
An encoding and decoding method of low density parity check code is disclosed. The method includes following steps: a high rate check code is transferred to a check matrix having a protograph. The check matrix is extended to form an extension base matrix and is split to form a splitting base matrix. The extension base matrix and the splitting base matrix are respectively calculated to generate their decoding threshold by a protograph extrinsic information transfer chart. The base matrix with the lower decoding threshold is considered as a low rate base matrix. Repeating the above process until a stopping condition is met. The last low rate base matrix is expanded to form a parity check matrix. The transmission data is encoded and decoded by the parity check matrix.