Compression of redundancy free trellis stages in turbo-decoder

For turbo codes with a coding rate close to one, the high puncturing rate induces long sequences of trellis without a redundancy bit. A simplification technique to compute the final state of a sequence of redundancy free trellis stages (RFTSs) is presented. It compresses a sequence of RFTSs of length N into a sequence of RFTSs of length m - 1 + (N mod (m - 1)), where m is the number of states of the trellis. The computation is reduced accordingly.