Full-Duplex Massive MIMO Relaying: An Energy Efficiency Perspective

This paper investigates the multi-pair full-duplex massive MIMO relaying, where multiple source-destination pairs communicate simultaneously with the help of a common full-duplex decode-and-forward relay. It is assumed that the sources and destinations are equipped with single antenna while the relay is equipped with very large antenna arrays. The asymptotic end-to-end signal-to-interference-plus-noise ratio (SINR) is analyzed under the general power scaling scheme, when maximal ratio combining/maximal ratio transmission scheme or zero-forcing reception/zero-forcing transmission scheme is employed at the relay. Theoretical results show that the effect of echo interference due to full-duplex operation can be eliminated by the large antenna arrays of the relay, if the power scaling scheme is selected properly. On the basis of the SINR expressions, the energy efficiency scaling law is derived. Furthermore, we present the power control scheme at the sources and relay to maximize the energy efficiency, subject to the required spectral efficiency and maximum power constraints. We show that the power control problem can be approximated as a geometric program problem and solved efficiently by the convex optimization tools. Numerical results are presented to validate the asymptotic analysis as well as the proposed power control scheme. The results demonstrate that the deployment of full-duplex relay is beneficial to achieve energy efficient transmission in massive MIMO relaying network.