Turbo codes and Shannon's condition for reliable communication

Block transmission over noisy communication channels is characterized by two performance criteria: the bit error probability P/sub b/ and the block error probability P/sub B/. If P/sub B/ goes to zero when N/spl rarr//spl infin/ (where N denotes the length of the permutors), P/sub b/ also must go to zero for all symbols in the block but, in general, the reverse is not true. Therefore we formulate the Shannon's condition for reliable communication over noisy channels. In this paper, we address the problem of reliable communication for iterative decoding of turbo codes.