676 research outputs found
On the MIMO Capacity with Residual Transceiver Hardware Impairments
Radio-frequency (RF) impairments in the transceiver hardware of communication
systems (e.g., phase noise (PN), high power amplifier (HPA) nonlinearities, or
in-phase/quadrature-phase (I/Q) imbalance) can severely degrade the performance
of traditional multiple-input multiple-output (MIMO) systems. Although
calibration algorithms can partially compensate these impairments, the
remaining distortion still has substantial impact. Despite this, most prior
works have not analyzed this type of distortion. In this paper, we investigate
the impact of residual transceiver hardware impairments on the MIMO system
performance. In particular, we consider a transceiver impairment model, which
has been experimentally validated, and derive analytical ergodic capacity
expressions for both exact and high signal-to-noise ratios (SNRs). We
demonstrate that the capacity saturates in the high-SNR regime, thereby
creating a finite capacity ceiling. We also present a linear approximation for
the ergodic capacity in the low-SNR regime, and show that impairments have only
a second-order impact on the capacity. Furthermore, we analyze the effect of
transceiver impairments on large-scale MIMO systems; interestingly, we prove
that if one increases the number of antennas at one side only, the capacity
behaves similar to the finite-dimensional case. On the contrary, if the number
of antennas on both sides increases with a fixed ratio, the capacity ceiling
vanishes; thus, impairments cause only a bounded offset in the capacity
compared to the ideal transceiver hardware case.Comment: Accepted for publication at the IEEE International Conference on
Communications (ICC 2014), 7 pages, 6 figure
Achievable Rate of Rician Large-Scale MIMO Channels with Transceiver Hardware Impairments
Transceiver hardware impairments (e.g., phase noise,
in-phase/quadrature-phase (I/Q) imbalance, amplifier non-linearities, and
quantization errors) have obvious degradation effects on the performance of
wireless communications. While prior works have improved our knowledge on the
influence of hardware impairments of single-user multiple-input multiple-output
(MIMO) systems over Rayleigh fading channels, an analysis encompassing the
Rician fading channel is not yet available. In this paper, we pursue a detailed
analysis of regular and large-scale (LS) MIMO systems over Rician fading
channels by deriving new, closed-form expressions for the achievable rate to
provide several important insights for practical system design. More
specifically, for regular MIMO systems with hardware impairments, there is
always a finite achievable rate ceiling, which is irrespective of the transmit
power and fading conditions. For LS-MIMO systems, it is interesting to find
that the achievable rate loss depends on the Rician -factor, which reveals
that the favorable propagation in LS-MIMO systems can remove the influence of
hardware impairments. However, we show that the non-ideal LS-MIMO system can
still achieve high spectral efficiency due to its huge degrees of freedom.Comment: 7 pages, 1 table, 3 figures, accepted to appear in IEEE Transactions
on Vehicular Technolog
Impact of Transceiver Impairments on the Capacity of Dual-Hop Relay Massive MIMO Systems
Despite the deleterious effect of hardware impairments on communication
systems, most prior works have not investigated their impact on widely used
relay systems. Most importantly, the application of inexpensive transceivers,
being prone to hardware impairments, is the most cost-efficient way for the
implementation of massive multiple-input multiple-output (MIMO) systems.
Consequently, the direction of this paper is towards the investigation of the
impact of hardware impairments on MIMO relay networks with large number of
antennas. Specifically, we obtain the general expression for the ergodic
capacity of dual-hop (DH) amplify-and-forward (AF) relay systems. Next, given
the advantages of the free probability (FP) theory with comparison to other
known techniques in the area of large random matrix theory, we pursue a large
limit analysis in terms of number of antennas and users by shedding light to
the behavior of relay systems inflicted by hardware impairments.Comment: 6 pages, 4 figures, accepted in IEEE Global Communications Conference
(GLOBECOM 2015) - Workshop on Massive MIMO: From theory to practice, 201
Towards a Realistic Assessment of Multiple Antenna HCNs: Residual Additive Transceiver Hardware Impairments and Channel Aging
Given the critical dependence of broadcast channels by the accuracy of
channel state information at the transmitter (CSIT), we develop a general
downlink model with zero-forcing (ZF) precoding, applied in realistic
heterogeneous cellular systems with multiple antenna base stations (BSs).
Specifically, we take into consideration imperfect CSIT due to pilot
contamination, channel aging due to users relative movement, and unavoidable
residual additive transceiver hardware impairments (RATHIs). Assuming that the
BSs are Poisson distributed, the main contributions focus on the derivations of
the upper bound of the coverage probability and the achievable user rate for
this general model. We show that both the coverage probability and the user
rate are dependent on the imperfect CSIT and RATHIs. More concretely, we
quantify the resultant performance loss of the network due to these effects. We
depict that the uplink RATHIs have equal impact, but the downlink transmit BS
distortion has a greater impact than the receive hardware impairment of the
user. Thus, the transmit BS hardware should be of better quality than user's
receive hardware. Furthermore, we characterise both the coverage probability
and user rate in terms of the time variation of the channel. It is shown that
both of them decrease with increasing user mobility, but after a specific value
of the normalised Doppler shift, they increase again. Actually, the time
variation, following the Jakes autocorrelation function, mirrors this effect on
coverage probability and user rate. Finally, we consider space division
multiple access (SDMA), single user beamforming (SU-BF), and baseline
single-input single-output (SISO) transmission. A comparison among these
schemes reveals that the coverage by means of SU-BF outperforms SDMA in terms
of coverage.Comment: accepted in IEEE TV
Massive MIMO Systems with Non-Ideal Hardware: Energy Efficiency, Estimation, and Capacity Limits
The use of large-scale antenna arrays can bring substantial improvements in
energy and/or spectral efficiency to wireless systems due to the greatly
improved spatial resolution and array gain. Recent works in the field of
massive multiple-input multiple-output (MIMO) show that the user channels
decorrelate when the number of antennas at the base stations (BSs) increases,
thus strong signal gains are achievable with little inter-user interference.
Since these results rely on asymptotics, it is important to investigate whether
the conventional system models are reasonable in this asymptotic regime. This
paper considers a new system model that incorporates general transceiver
hardware impairments at both the BSs (equipped with large antenna arrays) and
the single-antenna user equipments (UEs). As opposed to the conventional case
of ideal hardware, we show that hardware impairments create finite ceilings on
the channel estimation accuracy and on the downlink/uplink capacity of each UE.
Surprisingly, the capacity is mainly limited by the hardware at the UE, while
the impact of impairments in the large-scale arrays vanishes asymptotically and
inter-user interference (in particular, pilot contamination) becomes
negligible. Furthermore, we prove that the huge degrees of freedom offered by
massive MIMO can be used to reduce the transmit power and/or to tolerate larger
hardware impairments, which allows for the use of inexpensive and
energy-efficient antenna elements.Comment: To appear in IEEE Transactions on Information Theory, 28 pages, 15
figures. The results can be reproduced using the following Matlab code:
https://github.com/emilbjornson/massive-MIMO-hardware-impairment
Nuts and Bolts of a Realistic Stochastic Geometric Analysis of mmWave HetNets: Hardware Impairments and Channel Aging
© 2019 IEEE.Motivated by heterogeneous network (HetNet) design in improving coverage and by millimeter-wave (mmWave) transmission offering an abundance of extra spectrum, we present a general analytical framework shedding light on the downlink of realistic mmWave HetNets consisting of K tiers of randomly located base stations. Specifically, we model, by virtue of stochastic geometry tools, the multi-Tier multi-user (MU) multiple-input multiple-output (MIMO) mmWave network degraded by the inevitable residual additive transceiver hardware impairments (RATHIs) and channel aging. Given this setting, we derive the coverage probability and the area spectral efficiency (ASE), and we subsequently evaluate the impact of residual transceiver hardware impairments and channel aging on these metrics. Different path-loss laws for line-of-sight and non-line-of-sight are accounted for the analysis, which are among the distinguishing features of mmWave systems. Among the findings, we show that the RATHIs have a meaningful impact at the high-signal-To-noise-ratio regime, while the transmit additive distortion degrades further than the receive distortion the system performance. Moreover, serving fewer users proves to be preferable, and the more directive the mmWaves are, the higher the ASE becomes.Peer reviewedFinal Accepted Versio
MIMO Transmission with Residual Transmit-RF Impairments
Physical transceiver implementations for multiple-input multiple-output
(MIMO) wireless communication systems suffer from transmit-RF (Tx-RF)
impairments. In this paper, we study the effect on channel capacity and
error-rate performance of residual Tx-RF impairments that defy proper
compensation. In particular, we demonstrate that such residual distortions
severely degrade the performance of (near-)optimum MIMO detection algorithms.
To mitigate this performance loss, we propose an efficient algorithm, which is
based on an i.i.d. Gaussian model for the distortion caused by these
impairments. In order to validate this model, we provide measurement results
based on a 4-stream Tx-RF chain implementation for MIMO orthogonal
frequency-division multiplexing (OFDM).Comment: to be presented at the International ITG Workshop on Smart Antennas -
WSA 201
Hardware Impairments in Large-scale MISO Systems: Energy Efficiency, Estimation, and Capacity Limits
The use of large-scale antenna arrays has the potential to bring substantial
improvements in energy efficiency and/or spectral efficiency to future wireless
systems, due to the greatly improved spatial beamforming resolution. Recent
asymptotic results show that by increasing the number of antennas one can
achieve a large array gain and at the same time naturally decorrelate the user
channels; thus, the available energy can be focused very accurately at the
intended destinations without causing much inter-user interference. Since these
results rely on asymptotics, it is important to investigate whether the
conventional system models are still reasonable in the asymptotic regimes. This
paper analyzes the fundamental limits of large-scale multiple-input
single-output (MISO) communication systems using a generalized system model
that accounts for transceiver hardware impairments. As opposed to the case of
ideal hardware, we show that these practical impairments create finite ceilings
on the estimation accuracy and capacity of large-scale MISO systems.
Surprisingly, the performance is only limited by the hardware at the
single-antenna user terminal, while the impact of impairments at the
large-scale array vanishes asymptotically. Furthermore, we show that an
arbitrarily high energy efficiency can be achieved by reducing the power while
increasing the number of antennas.Comment: Published at International Conference on Digital Signal Processing
(DSP 2013), 6 pages, 5 figure
Hardware Impairments Aware Transceiver Design for Full-Duplex Amplify-and-Forward MIMO Relaying
In this work we study the behavior of a full-duplex (FD) and
amplify-and-forward (AF) relay with multiple antennas, where hardware
impairments of the FD relay transceiver is taken into account. Due to the
inter-dependency of the transmit relay power on each antenna and the residual
self-interference in an FD-AF relay, we observe a distortion loop that degrades
the system performance when the relay dynamic range is not high. In this
regard, we analyze the relay function in presence of the hardware inaccuracies
and an optimization problem is formulated to maximize the signal to
distortion-plus-noise ratio (SDNR), under relay and source transmit power
constraints. Due to the problem complexity, we propose a
gradient-projection-based (GP) algorithm to obtain an optimal solution.
Moreover, a nonalternating sub-optimal solution is proposed by assuming a
rank-1 relay amplification matrix, and separating the design of the relay
process into multiple stages (MuStR1). The proposed MuStR1 method is then
enhanced by introducing an alternating update over the optimization variables,
denoted as AltMuStR1 algorithm. It is observed that compared to GP, (Alt)MuStR1
algorithms significantly reduce the required computational complexity at the
expense of a slight performance degradation. Finally, the proposed methods are
evaluated under various system conditions, and compared with the methods
available in the current literature. In particular, it is observed that as the
hardware impairments increase, or for a system with a high transmit power, the
impact of applying a distortion-aware design is significant.Comment: Submitted to IEEE Transactions on Wireless Communication
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