Low-Complexity List-Based Frame Synchronization for LDPC Coded Transmission

In this paper, we propose a simple and efficient two-stage list synchronizer for frame synchronization of Low-Density Parity-Check (LDPC) coded data transmitted over the Additive White Gaussian Noise (AWGN) channel. The proposed method uses both synchronization sequence and code constraints for frame synchronization. In the first stage, a list of the most likely frame starting positions is made using synchro-sequence, while in the second stage the code constraints are used to select the most likely position from the list. We analytically relate the synchro-sequence length, the frame length and the list length in order to keep the synchronization frame error rate (FER) lower than the error-correcting FER of the LDPC code, and we investigate the trade-off between the sequence length and the list length. We demonstrate that the proposed scheme outperforms both the frame synchronization methods based on synchro-sequence only and the recently proposed blind synchronization methods based on LDPC code constraints, the former in terms of the synchronization FER for the same sequence lengths and the latter in terms of complexity.