Pairwise Check Decoding for LDPC Coded Two-Way Relay Fading Channels

We present a novel partial decoding method at the relay, called pairwise check decoding (PCD), for two-way relay fading channels. The proposed PCD method forms a so-called check-relationship table for the superimposed Low-Density Parity-Check (LDPC)-coded packet pair during the multiple access phase. Meanwhile, it incorporates adaptive network coding by using closest-neighbor clustering mapping (CNCM) to compensate the phase deviation of the fading channels. The proposed PCD method is a practical and efficient realization of the promising denoise-and-forward relay strategy with advanced channel coding and non-linear network coding. Simulation results show that under the same LDPC-coded two-way relay system, our proposed PCD considerably outperforms the case where the relay performs only adaptive network coding without channel decoding. It also performs better than the case where the relay adopts the belief propagation decoding along with conventional XOR-based network coding under certain regions.