Multi-Pair Bidirectional Relaying with Full-Duplex Massive MIMO Experiencing Channel Aging

In this paper, we study a multi-pair bidirectional (or two-way) full-duplex (FD) massive MIMO relay (FDMMR) system, where the relay employs massive antennas and is operated in the amplify-and-forward (AF) mode. We analyze its spectral efficiency (SE) performance, when both imperfect channel estimation and channel aging effect are considered. We propose four power-scaling schemes based on the zero-forcing reception/zero-forcing transmission (ZFR/ZFT) relaying processing. Assuming that the number of relay antennas approaches infinity, the SE is analyzed in the context of the proposed power scaling schemes. Our analytical results show that the inter-pair interference caused by the other user pairs as well as the self-interference can be completely eliminated by the ZFR/ZFT processing at the relay. The self-loop interference and the inter- user interference can also be cancelled, if a power scaling scheme is carefully selected. Furthermore, our studies show that the channel aging may significantly degrade the SE of the system.