The systematic and parity bits of a symbol are tightly coupled to each other based on the way in which the symbol is encoded. The relationship between the systematic and parity bits can be exploited to improve the accuracy of soft bit estimation for both the systematic bits and parity bits. In one embodiment, a received symbol is processed by demodulating the received symbol to determine an initial soft estimate of each systematic bit and corresponding one or more parity bits in the sequence. The systematic bit sequence is iteratively decoded to revise the soft estimate of the systematic bit. The initial soft estimate of the one or more parity bits associated with each systematic bit is revised based on the revised soft estimate of each systematic bit. The received symbol can be decoded or regenerated based on the revised soft estimate of each systematic bit and corresponding one or more parity bits.