Adaptive iterative phase synchronization for serially concatenated continuous phase modulation

An adaptive iterative detection structure is proposed for serially concatenated continuous phase modulation (SCCPM) on unknown channels. Joint phase synchronization and detection are implemented by means of a set of suboptimal adaptive soft-input soft-output (SISO) algorithms. The forward-only adaptive algorithms are found more robust than the forward-backward adaptive algorithms in tracking and acquiring a time-varying channel, due to rotational invariance of CPM trellis. Simulation results also show that the performance of the proposed forward-only adaptive iterative receiver closely approach that of iterative receivers with perfect knowledge of phase offset.