Effects of the Number of Relay Antennas and Relay-power on Mimo Precoded Two-way Relaying

In this treatise a two-way Amplify and Forward (AF) relay-aided system is considered, which employs the so-called Arithmetic Sum of Average Bit Error Rate (ASABER) based MIMO precoding technique. The two-way AF relay system is comprised of the pair of transceiver nodes S1 and S2, and the Relay Node (RN) R, where each node is equipped with N1, N2 and Nr antennas, respectively. We study the effects of varying Nr for fixed values of N1 and N2, and as well as the effects of having a fixed transmission power at the RN on the achievable ASABER performance. Based on our intensive simulation campaign, we infer that the attainable diversity order is increased approximately by Nr − min (N1, N2), whenever Nr assumes a value higher than min (N1, N2) for fixed N1, N2 values. However, this is observation is only valid for relay power pr  (p1, p2), where p1 and p2 are the transmit power constraints imposed on the sources S1 and S2, respectively. We also observe that the ASABER MIMO precoder’s BER curve exhibits an error floor for pr ≤ (p1, p2).