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_b and the block error probability P_B. If P_B goes to zero when N→∞ (where N denotes the length of the permutors), P_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.