Recent works have identified massive multiple-input-multiple-output (MIMO) as
a key technology for achieving substantial gains in spectral and energy
efficiency. Additionally, the turn to low-cost transceivers, being prone to
hardware impairments is the most effective and attractive way for
cost-efficient applications concerning massive MIMO systems. In this context,
the impact of channel aging, which severely affects the performance, is
investigated herein by considering a generalized model. Specifically, we show
that both Doppler shift because of the users' relative movement as well as
phase noise due to noisy local oscillators (LOs) contribute to channel aging.
To this end, we first propose a joint model, encompassing both effects, in
order to investigate the performance of a massive MIMO system based on the
inevitable time-varying nature of realistic mobile communications. Then, we
derive the deterministic equivalents (DEs) for the
signal-to-noise-and-interference ratios (SINRs) with maximum ratio transmission
(MRT) and regularized zero-forcing precoding (RZF). Our analysis not only
demonstrates a performance comparison between MRT and RZF under these
conditions, but most importantly, it reveals interesting properties regarding
the effects of user mobility and phase noise. In particular, the large antenna
limit behavior depends profoundly on both effects, but the burden due to user
mobility is much more detrimental than phase noise even for moderate user
velocities ($\approx30$ km/h), while the negative impact of phase noise is
noteworthy at lower mobility conditions.

本文研究了基于低成本收发器的大规模 MIMO 系统中信道老化问题，并通过提出联合模型，分析了 Doppler 频移和本地振荡器相位噪声对信道老化问题的影响。在此基础上，作者进一步推导出使用最大比传输和正则化零强制预编码的信干噪比确定等效情况下，这两种传输策略的性能比较，并探讨了用户移动性和本地振荡器相位噪声对大规模 MIMO 系统影响的差异。

普通信道老化条件对大规模 MIMO 下行性能的影响

Impact of General Channel Aging Conditions on the Downlink Performance  of Massive MIMO

This paper investigates the achievable sum-rate of massive multiple-input
multiple-output (MIMO) systems in the presence of channel aging. For the
uplink, by assuming that the base station (BS) deploys maximum ratio combining
(MRC) or zero-forcing (ZF) receivers, we present tight closed-form lower bounds
on the achievable sum-rate for both receivers with aged channel state
information (CSI). In addition, the benefit of implementing channel prediction
methods on the sum-rate is examined, and closed-form sum rate lower bounds are
derived. Moreover, the impact of channel aging and channel prediction on the
power scaling law is characterized. Extension to the downlink scenario and
multi-cell scenario are also considered. It is found that, for a system
with/without channel prediction, the transmit power of each user can be scaled
down at most by $1/\sqrt{M}$ (where $M$ is the number of BS antennas), which
indicates that aged CSI does not degrade the power scaling law, and channel
prediction does not enhance the power scaling law; instead, these phenomena
affect the achievable sum-rate by degrading or enhancing the effective signal
to interference and noise ratio, respectively.

研究了大规模 MIMO 系统在信道老化情况下的可实现总速率，包括采用最大比合并或零强制接收机的上行情况和采用信道预测方法的影响，得出了最小可实现总速率和信道老化、信道预测对发射功率缩放规律的影响，发现信道老化和信道预测会分别降低或提高有效信干比，从而影响可实现总速率。

大规模 MIMO 系统的和速率和功率缩放与信道老化

Sum-Rate and Power Scaling of Massive MIMO Systems with Channel Aging

MIMO communication may provide high spectral efficiency through the
deployment of a very large number of antenna elements at the base stations. The
gains from massive MIMO communication come from the use of multi-user MIMO on
the uplink and downlink, but with a large excess of antennas at the base
station compared to the number of served users. Initial work on massive MIMO
did not fully address several practical issues associated with its deployment.
This paper considers the impact of channel aging on the performance of massive
MIMO systems. The effects of channel variation are characterized as a function
of different system parameters assuming a simple model for the channel time
variations at the transmitter. Channel prediction is proposed to overcome
channel aging effects. The analytical results on aging show how capacity is
lost due to time variation in the channel. Numerical results in a multicell
network show that massive MIMO works even with some channel variation and that
channel prediction could partially overcome channel aging effects.

本研究考虑了信道老化对大规模 MIMO 系统性能的影响及其预测方法。结果表明，即使存在一定的信道变化，大规模 MIMO 系统仍能工作，并且信道预测可以部分地克服信道老化效应。