On the Sum Rate of Multi-User Full-Duplex Massive MIMO Systems

In this paper, we consider multi-user multiple-input multiple-output (MU-MIMO) system with a full-duplex (FD) base station (BS) and a number of FD users. The BS is equipped with large-scale antenna arrays, while each user is equipped with two antennas (one for transmitting and the other one for receiving). The linear signal processing technique based on the maximum-ratio combining/maximum-ratio transmission (MRC/MRT) is adopted at the BS. The asymptotic expressions of signal-to-interference-plus-noise ratio (SINR) of uplink and downlink are derived respectively when the number of antennas of the BS tends to infinity. Through the theoretical derivation, it is shown that the detrimental impact of the loop interference (LI) can be eliminated by the very large number of antennas at the BS if the power scaling scheme is appropriately applied, as well as the effect of multi-user interference (MUI) and inter-user interference (IUI). Moreover, the Monte Carlo simulations show that the spectral efficiency of the multi-user full-duplex massive MIMO system is better than the half-duplex (HD) counterpart when the number of receive/transmit antennas at the BS is large.