OFDM-CPM signals in two-way relay channels with physical-layer network coding

Physical-layer network coding (PNC) has obtained much attention due to its ability to improve throughput in relay-aided communications. In this paper, we introduce orthogonal frequency division multiplexing-continuous phase modulation (OFDM-CPM) signals into a two-way relay (TWR) channel adopting the PNC protocol to form a new scheme. With PNC, the TWR communication is performed during two phases. In the multiple access (MAC) phase, the two users send OFDM-CPM signals concurrently to the relay, and the relay broadcasts the XORed version of the two users´ data in the broadcast phase. We focus on the MAC phase and present a decoding scheme for the relay receiver. The error performance of the new scheme is provided by simulation results, and it is shown that the proposed scheme outperforms that of OFDM-PSK for PNC over frequency-selective fading channels.