A maximum-likelihood based feedback carrier synchronizer for turbo-coded systems

This contribution considers the estimation of a time-varying carrier phase from coded signals at low operating SNR. ML estimation theory is used to derive an iterative code-aided feedback phase-tracker that is well suited for application in receivers with iterative MAP detection. Simulation results for a turbo-coded system indicate that, in the presence of carrier frequency offsets and phase noise that cannot be handled by a feedforward synchronizer, the proposed synchronizer yields only a small BER degradation as compared to a perfectly synchronized receiver.