The effect upon channel capacity in wireless communications of perfect and imperfect knowledge of the channel

Médard, Muriel

doi:10.1109/18.841172

Cited by 823 publications

(653 citation statements)

References 62 publications

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“…For this reason, we use similar techniques to [40], in order to obtain an expression for the downlink sum-rate under the assumption that user m, found in cell j, has knowledge of only…”

Section: B Downlink Transmissionmentioning

confidence: 99%

“…The downlink deterministic equivalent SINR at user m in cell j with RZF precoding and predicted CSI by using a pth-order Wiener filter is given by (40) …”

Section: Theoremmentioning

confidence: 99%

“…As far as the downlink is concerned, expressions (39) and (40) reduce to Theorem 6 of [10], if α = 1 and p = 0. The pilot contamination affects the downlink sum-rate in the same way as in the uplink, while delayed CSIT affects apart of the desired channel and the interference channel from BS l belonging to different cells (l = j), but also the term corresponding to the channel estimation error.…”

Section: Theoremmentioning

confidence: 99%

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Deterministic Equivalent Performance Analysis of Time-Varying Massive MIMO Systems

Papazafeiropoulos

Ratnarajah

2015

IEEE Trans. Wireless Commun.

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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.

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“…For this reason, we use similar techniques to [40], in order to obtain an expression for the downlink sum-rate under the assumption that user m, found in cell j, has knowledge of only…”

Section: B Downlink Transmissionmentioning

confidence: 99%

“…The downlink deterministic equivalent SINR at user m in cell j with RZF precoding and predicted CSI by using a pth-order Wiener filter is given by (40) …”

Section: Theoremmentioning

confidence: 99%

Section: Theoremmentioning

confidence: 99%

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Deterministic Equivalent Performance Analysis of Time-Varying Massive MIMO Systems

Papazafeiropoulos

Ratnarajah

2015

IEEE Trans. Wireless Commun.

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“…Let H be the actual channel, H be the estimated channel and ∆ = H − H denote the estimation error matrix. We begin with the following well-known lower-bound [26] to C train,1,LT (SNR):…”

Section: A Achievable Rates Under Average Power Constraintmentioning

confidence: 99%

Capacity of sparse wideband channels with partial channel feedback

Hariharan

Raghavan

Sayeed

2008

Trans Emerging Tel Tech

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This paper studies the ergodic capacity of wideband multipath channels with limited feedback. Our work builds on recent results that have established the possibility of significant capacity gains in the wideband/low-SNR regime when there is perfect channel state information (CSI) at the transmitter.Furthermore, the perfect CSI benchmark gain can be obtained with the feedback of just one bit per channel coefficient. However, the input signals used in these methods are peaky, that is, they have a large peak-to-average power ratios. Signal peakiness is related to channel coherence and many recent measurement campaigns show that, in contrast to previous assumptions, wideband channels exhibit a sparse multipath structure that naturally leads to coherence in time and frequency. In this work, we first show that even an instantaneous power constraint is sufficient to achieve the benchmark gain when perfect CSI is available at the receiver. In the more realistic non-coherent setting, we study the performance of a training-based signaling scheme. We show that multipath sparsity can be leveraged to achieve the benchmark gain under both average as well as instantaneous power constraints as long as the channel coherence scales at a sufficiently fast rate with signal space dimensions. We also present rules of thumb on choosing signaling parameters as a function of the channel parameters so that the full benefits of sparsity can be realized.

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“…The effect of imperfect CSI on the capacity of point-topoint SISO and MIMO channels has been studied in [2], [8], and [3]. The robustness of the capacity achieving scheme in a Gaussian flat-fading channel is studied in [4].…”

Section: Introductionmentioning

confidence: 99%

The Effect of Channel Estimation Error on the Throughput of Broadcast Channels

Vakili

Sharif

Hassibi

2006 IEEE International Conference on Acoustics Speed and Signal Processing Proceedings

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In a broadcast channel in which one transmitter serves receivers, the capacity region highly depends on the amount of channel state information (CSI) at the transmitter. Assuming that the transmitter knows the SNR of all the receivers, opportunistic strategy maximizes the throughput (sum-rate) of the system. It is usually assumed that CSI is accurate, however, evaluating the SNR is basically an estimation problem in the receiver which cannot be done without error. In this paper, we analyze the effect of the noisy estimation of SNR on the throughput of a broadcast channel. We propose a generalization of the opportunistic transmission in which the transmitter still sends to the user with the highest estimated SNR, but backs off on the transmit rate based on the variance of the estimation error. We obtain the optimum amount of back off and compute the throughput for our scheduling scheme. Clearly, the estimation can be improved by using a longer training phase; however, longer training would deteriorate the throughput. In the final part of the paper, we address this trade off and obtain the optimum training strategy that maximizes the throughput of the system.

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The effect upon channel capacity in wireless communications of perfect and imperfect knowledge of the channel

Cited by 823 publications

References 62 publications

Deterministic Equivalent Performance Analysis of Time-Varying Massive MIMO Systems

Deterministic Equivalent Performance Analysis of Time-Varying Massive MIMO Systems

Capacity of sparse wideband channels with partial channel feedback

The Effect of Channel Estimation Error on the Throughput of Broadcast Channels

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