Differentially-encoded turbo coded modulation with APP channel estimation

A simple serially concatenated turbo code using differential 8PSK encoding as the inner code and a [3,2,2] parity code as the outer code is studied. This system is decoded coherently according to turbo principles with iterative exchange of extrinsic probabilities. Decoding over channels without prior synchronization is demonstrated to be feasible even with significant phase offset, using a simple channel estimator that utilizes the extrinsic output symbol probabilities from the differential APP decoder, which is termed APP channel estimation.