Constrained coding and soft iterative decoding

Constrained coding and error-control coding (ECC) are considered in a combined framework. In the context of soft iterative decoding, this allows the ECC decoder (e.g., for a turbo or LDPC code) to gain direct access to the probabilities from the channel decoder. In addition, a soft decoder for the constraint can be introduced to yield additional coding gain. Practical methods for combining the constraint and ECC include a modified concatenation scheme and a bit insertion scheme.