Low-complexity iterative carrier phase and symbol timing recovery approach for turbo-codes system

A low-complexity iterative synchronisation approach suited to turbo-coded systems is proposed in this paper. The estimation of carrier phase and symbol timing is based on the maximum likelihood estimation (MLE) theory. The synchronisers perform once per decoding iteration and make iterative use of extrinsic information obtained from the turbo decoder. In this way, the recovery of the carrier phase and symbol timing are integrated into the iteration loop of the turbo decoding and carried out simultaneously with the decoding iteration by iteration. The approach is applied to turbo-coded BPSK system over AWGN channel. Simulation results demonstrate that this approach provides reliable estimation on the phase and timing errors and robust decoding at low SNR values without using additional pilot. symbols. It is shown that this approach outperforms the traditional non-data-aided (NDA) method and the overall BER performance approaches that with ideal synchronisation.