Simplified Iterative Symbol Timing and Carrier Phase Recovery Scheme for LDPC-Coded Systems

A simplified ML-based iterative synchronization scheme is proposed in this paper for LPDC-coded systems. Symbol timing and carrier phase are estimated in a simple way based on the maximum likelihood theory aided by hard decision obtained from LDPC decoder. The synchronized samples input to the decoder are updated when a new iterative estimation for symbol timing and carrier phase is completed. The synchronized samples are reconstructed by quadratic interpolation which is very simple and can be implemented in parallel. This approach is applied to a LDPC-coded QPSK system over AWGN channel. Simulation results demonstrate that the performance of the proposed scheme approaches that with the ideal synchronization