Deterministic Equivalent Performance Analysis of Time-Varying Massive MIMO Systems

Abstract

Abstract-Delayed channel state information at the transmitter (CSIT) due to time variation of the channel, coming from the users' relative movement with regard to the BS antennas, is an inevitable degrading performance factor in practical systems. Despite its importance, little attention has been paid to the literature of multi-cellular multiple-input massive multiple-output (MIMO) system by investigating only the maximal ratio combining (MRC) receiver and the maximum ratio transmission (MRT) precoder. Hence, the contribution of this work is designated by the performance analysis/comparison of/with more sophisticated linear techniques, i.e., a minimum-mean-square-error (MMSE) detector for the uplink and a regularized zero-forcing (RZF) precoder for the downlink are assessed. In particular, we derive the deterministic equivalents of the signal-to-interference-plus-noise ratios (SINRs), which capture the effect of delayed CSIT, and make the use of lengthy Monte Carlo simulations unnecessary. Furthermore, prediction of the current CSIT after applying a Wiener filter allows to evaluate the mitigation capabilities of MMSE and RZF. Numerical results depict that the proposed achievable SINRs (MMSE/RZF) are more efficient than simpler solutions (MRC/MRT) in delayed CSIT conditions, and yield a higher prediction at no special computational cost due to their deterministic nature. Nevertheless, it is shown that massive MIMO are preferable even in time-varying channel conditions.

Combating Massive MIMO Channel Aging by Orthogonal Precoding

“…i.e., for each element (q, m) of the time-frequency grid, maximum ratio combining is achieved. With beam-forming according to (5), the combined channel becomes almost frequency flat and non time-selective (assuming favorable propagation conditions). For A → ∞ these conclusion becomes exact [1].…”

“…Due to this outdated CSI the channel hardening effect of massive MIMO decreases with longer frame duration and increasing user velocity [4]. Previous work either considers a quasi static scenario where the uplink and downlink phase take part within a so called coherence interval [1] or performs channel prediction between the uplink and downlink transmission [4], [5] using long-term statistical information.…”

Modeling and Performance of Uplink Cache-Enabled Massive MIMO Heterogeneous Networks

“…Remarkably, following the procedure in [21], we are able to write both pilot contamination and time-variation of the channel as a combination. More concretely, the channel at time slot n can be written as h llk,n = δh llk,n−1 + e llk,n = δĥ llk,n−1 +ẽ llk,n ,…”

“…The achievement of high cell-throughput along with simple signal processing has been contrived by deploying large-scale antenna arrays at the BS and multi-user (MU) transmission. Starting from the strong assumption of perfect CSI, research has faced realistic impediments such as the presence of pilot contamination [18] and [16], the inevitable hardware impairments [19] and [20], as well as the channel aging [21]- [23]. Especially, by applying the theory of deterministic equivalent (DE) analysis, massive MIMO systems were studied under the presence of channel aging [21].…”

Impact of Residual Additive Transceiver Hardware Impairments on Rayleigh-Product MIMO Channels With Linear Receivers: Exact and Asymptotic Analyses

“…Turning the focus into the emerging technology of massive MIMO, where a BS is deployed with a large number of antennas and achieves a number of interesting properties such as high gain and ease of implementation, most works assume ideal transceiver hardware [29], [30]. Given that massive MIMO systems are supposed to be implemented with low-cost hardware, and hence are more prone to impairments, this is a strong assumption.…”