The present invention provides for applying a cyclic redundancy check (CRC) to a data signal. The present invention includes attaching a first CRC to a first data signal block having a first length, segmenting the first data signal block attached with the first CRC into a plurality of second data signal blocks having a length shorter than the first length, respectively generating a second CRC for each second data signal block, and attaching the generated second CRC to the respective second data signal block. Moreover, the first CRC and second CRC may be generated from respectively different CRC generating polynomial equations.