Parity-check-bit-inserted turbo code

The BER curve of a turbo code consists of two regions, the error-floor region and waterfall region. In the error-floor region, the codewords, which have the minimum input weight, are the main factors in the error performance. In the waterfall region, the code multiplicity as well as the minimum input weight codewords is the main factor. The parity-check-bit-inserted turbo code is introduced. By inserting parity bits in the information bits, the minimum input weight can be changed to a larger number, and the error performance in the error-floor region can be improved. Moreover in the decoding process, the iteration number is changed adaptively according to the information parity check, so that sufficiently error-free decoding can be performed.