Massive Mimo Aided Secure Multi-Pair Relaying With Power Control

We consider in this paper the physical layer security of multi-pair communication in massive MIMO aided amplify-and-forward (AF) relaying, where an eavesdropper (Eve) may intercept the information intended to any of the destinations. We derive closed-form deterministic equivalents of the end-to-end signal to interference-plus-noise ratios of legitimate users and Eve. We assume that the AF processing as well as the artificial noise generated at the relay are based on the imperfect channel state information of both hops. A particular result of the asymptotic analysis shows that by simply increasing the transmit power at the sources or relay the reachable security is limited by an upper bound. Nevertheless, the security can be strongly improved with a low-complexity power control at the relay, whose performance is evaluated in simulations.