Approach to frame-misalignment in physical-layer network coding

By exploiting superimposed signals at relays, physicallayer network coding (PNC) could significantly improve the throughput of wireless communications systems. However, it is challenging to achieve perfect synchronization between superimposed signals at the relay. In this paper, we propose an approach to resolve the issue of frame-misalignment in PNC using type-I Euclidean geometry low-density parity-check (EG-LDPC) codes with cyclic prefix or zero padding. To estimate the arrival delay between two transmitted signals at the relay, Gold sequences are adopted as pilot sequences in our transmit frames. Simulation results show that our approach can effectively resolve the frame-misalignment issue in PNC.