SUMMARY
Multiple-pair two-way communication in massive multiple-input multiple-output (MIMO) relay network is studied in this article wherein K single antenna source nodes exchange 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 two-way multiple-pair communication in Massive MIMO relay network through the precoding design at relay is addressed. It is shown hat, even with the imperfect channel state information at the relay, the maximum ratio combining-maximum ratio transmission (MRC/MRT) precoding and the zero-forcing reception zero-forcing transmission (ZFR/ZFT) precoding at relay can be employed to mitigate inter-pair interference. The asymptotic signal to interference plus noise ratio (SINR) analysis of four power-scaling schemes in the regime of very large number of antenna at relay shows that, the inter-pair interference can be eliminated, the effect of the small-scale fading can be averaged out; the total transmit power consumption can be reduced for a better energy efficient multiple-pair communication when the number of antenna at relay is large enough. Moreover, when the transmit power at relay is sufficient, both the MRC/MRT and the ZFR/ZFT based relaying strategy can effectively cope with the channel state information (CSI) error. Simulation results are presented to validate our analysis.