Diversity achieving schemes for two-way multi-antenna relay networks in Nakagami-m fading

In this study, two diversity achieving schemes in two-way relay channel (TWRC) under Nakagami-m fading are proposed. A general network of N-r relays is considered where each relay is equipped with N-a antennas. It is also assumed that the relays operate in decode-and-forward (DF) mode. The data transmission is divided into two phases, multiple access (MAC) phase and broadcast (BC) phase. In the MAC phase, the sources send their data to the relays simultaneously and after decoding, one relay is selected with MAX-MIN relay selection criterion and then in the BC phase retransmit the decoded symbols using the proposed transmission schemes at the selected relay. With evaluating the asymptotic behaviour of the bit error rate (BER) of the proposed schemes, it is proved that the diversity order of them is N(r)N(a)m. As a result, the proposed schemes achieve full diversity order.