On the energy efficient multiple-pair communication in massive MIMO relay networks

In this paper, we consider multiple-pair communication in massive MIMO relay network, wherein K single antenna source nodes deliver their messages to the corresponding K single antenna destination nodes with the help of one relay provisioned with N(N >> K) antenna array. And the energy efficient multiple-pair communication in Massive MIMO relay network through the precoding at both sources and relay is addressed. It is shown that, given the channel state information at the source nodes and the relay, the zero-forcing precoding at all source nodes, the zero-forcing reception and zero-forcing transmission (ZFR/ZFT) or the zero-forcing reception and maximum ratio transmission (ZFR/MRT) at relay can be employed to mitigate inter-pair interference. The asymptotical analysis shows that, the required transmit power at relay can be made inversely proportional to the number of relay antennas without sacrificing the achieved energy efficiency. And the optimal power allocation problem is further formulated to address the power allocation design at all source nodes and the relay according to the large-scale fading for a better energy efficiency, when fulfilling some predefined sum rate performance requirements.