Estimatioin of codeword length and reconstruction methods of standard block interleaver for unknown signals by using the linearity of a channel code and apparatus for performing the same

PURPOSE: A method for estimating the codeword length of unknown signals using the linearity of a channel coding and restoring regular block interleaver, and a device for executing the same are provided to decode signals having unknown information in a special communications condition by restoring data stream to the codeword before interleaving. CONSTITUTION: The cycle of an interleaver is estimated(S610). The cycle of the interleaver is estimated based on the cycle of the interleaver(S620). The codeword is estimated based on the deinterleaver matrix, thereby rearranging the deinterleaver matrix. The deinterleaver matrix estimates the size into different value in the absence of codeword length to increase linearity(S640). The goaled deinterleaver matrix is re-constructed in the reception end. The stream is restored(S650).