On the Achievable Rates of Full-Duplex Massive MIMO Systems Under Channel Aging

The phenomenon of channel aging is caused by the temporal variation of wireless channels due to user mobility, and leads to an increasing mismatch between the true and estimated channels over time. This, in turn, degrades the signal-to-interference-plus-noise ratio (SINR), and reduces the throughput. In this paper, we analyze the impact of channel aging on the uplink (UL) and downlink (DL) data rates of a full-duplex (FD) multi-user massive multiple-input multiple-output (MIMO) system. We study this effect by deriving the deterministic equivalents for the SINR and achievable UL and DL rate regions. Our analysis accounts for the effects of channel aging, channel estimation errors, inter-user interference, and self-interference at the FD-enabled massive MIMO transceiver. For comparison, we also present the achievable rate of conventional time division duplex (TDD) and frequency division duplex (FDD) systems. Our analysis shows that while the operating point of achievable UL and DL rate pair is heavily dependent on the time (for TDD) and frequency (for FDD) resources allocated, the performance with FD is determined primarily by the relative UL and DL powers. Also, the FD system is significantly more resilient to channel aging effects, leading to improved achievable rates, especially at high user mobilities.