Coherent detecting and mapping scheme in two-way relay channels with 2FSK modulated physical-layer network coding

In this paper, we proposed a coherent detecting and mapping scheme for the relay node in two-way relay channels (TWRC) with binary frequency-shift keying (2FSK) modulated physical-layer network coding (PNC). The scheme use two branches to process the superimposed signal, sample and make decision to the difference of the output signal from the two branches, and then, map the decision result to network coded bits. We obtained the decision thresholds according to the maximum posterior probability decision rule, and analysed the decision error probability (DEP) of the relay node, the bit error rate (BER) of the whole system and the throughput performance. The analysis and numerical results show that, with this scheme, the DEP of relay node and the system's BER in PNC are close to traditional and network coding schemes, but the throughput of the proposed scheme is higher than these two schemes.