Joint blind frame synchronization and encoder identification for LDPC codes

In this paper, we would like to tackle joint blind frame synchronization and encoder identification of binary low-density parity-check (LDPC) codes for binary phase-shift keying (BPSK) signals. The unknown encoder and the unknown time-delay can be blindly estimated at the same time using the average log-likelihood ratios (LLRs) of syndrome a posteriori probability (APP). To reduce the complexity of the blind frame synchronization, we propose a two-stage search method with a search step-size q by exploiting the quasi-cyclic property of the parity-check matrix. Our proposed new joint scheme is evaluated by the probability of detection resulting from numerous Monte Carlo simulations. The simulation results demonstrate the effectiveness of our proposed joint blind frame-synchronization and encoder-identification scheme for multi-path situations.