Monotonicity Results for Coherent MIMO Rician Channels

Hoesli, Daniel; Kim, Young-Han; Lapidoth, Amos

doi:10.1109/tit.2005.858968

Cited by 35 publications

(29 citation statements)

References 23 publications

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“…In fact, since the hypergeometric function in (67) decreases monotonically if either n ⇓ or n ⇑ grow, the behavior of Corollary 13 extends to any rank-1 Ricean channel with n ⇓ ≥ 2. It is worth contrasting this finding with the result put forth in [37,38] (for arbitrary SNR), namely, that if the power received over the fading portion of the channel is held constant, then an unfaded component can only increase the mutual information. If the total received power is held constant, then this is not the case (at high SNR).…”

Section: Corollary 13mentioning

confidence: 72%

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High-SNR Power Offset in Multiantenna Communication

Lozano¹,

Tulino

Verdú

2005

IEEE Trans. Inform. Theory

252

174

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The analysis of the multiantenna capacity in the high-SNR regime has hitherto focused on the high-SNR slope (or maximum multiplexing gain), which quantifies the multiplicative increase as function of the number of antennas. This traditional characterization is unable to assess the impact of prominent channel features since, for a majority of channels, the slope equals the minimum of the number of transmit and receive antennas. Furthermore, a characterization based solely on the slope captures only the scaling but it has no notion of the power required for a certain capacity. This paper advocates a more refined characterization whereby, as function of SNR| dB , the high-SNR capacity is expanded as an affine function where the impact of channel features such as antenna correlation, unfaded components, etc, resides in the zero-order term or power offset. The power offset, for which we find insightful closed-form expressions, is shown to play a chief role for SNR levels of practical interest.

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Section: Corollary 13mentioning

confidence: 72%

“…• is also given by (37), (38) and (39), except with Λ distributed according to the limiting empirical distribution of the diagonal entries of Λ T .…”

Section: The Limiting Value Of L ∞mentioning

confidence: 99%

High-SNR Power Offset in Multiantenna Communication

Lozano¹,

Tulino

Verdú

2005

IEEE Trans. Inform. Theory

252

174

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“…This model is used in [5], [6], [21], [22], [23]. In this model, the transmitters have line-ofsight component with the receiver.…”

Section: System Modelmentioning

confidence: 99%

Optimality of beamforming in fading MIMO multiple access channels

Soysal

Ulukuş

2009

IEEE Trans. Commun.

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Abstract-We consider the sum capacity of a multi-input multi-output (MIMO) multiple access channel (MAC) where the receiver has the perfect channel state information (CSI), while the transmitters have either no or partial CSI. When the transmitters have partial CSI, it is in the form of either the covariance matrix of the channel or the mean matrix of the channel. For the covariance feedback case, we mainly consider physical models that result in single-sided correlation structures. For the mean feedback case, we consider physical models that result in in-phase received signals. Under these assumptions, we analyze the MIMO-MAC from three different viewpoints. First, we consider a finite-sized system. We show that the optimum transmit directions of each user are the eigenvectors of its own channel covariance and mean feedback matrices, in the covariance and mean feedback models, respectively. Also, we find the conditions under which beamforming is optimal for all users. Second, in the covariance feedback case, we prove that the region where beamforming is optimal for all users gets larger with the addition of new users into the system. In the mean feedback case, we show through simulations that this is not necessarily true. Third, we consider the asymptotic case where the number of users is large. We show that in both no and partial CSI cases, beamforming is asymptotically optimal. In particular, in the case of no CSI, we show that a simple form of beamforming, which may be characterized as an arbitrary antenna selection scheme, achieves the sum capacity. In the case of partial CSI, we show that beamforming in the direction of the strongest eigenvector of the channel feedback matrix achieves the sum capacity. Finally, we generalize our covariance feedback results to double-sided correlation structures in the Appendix.Index Terms-Multi-user MIMO, MIMO multiple access channel, partial CSI, covariance feedback, mean feedback, optimality of beamforming, large system analysis.

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“…In this case, the problem of finding the optimum covariance matrices is still open in the general setting [6]. A notable result in this area has been provided by Hösli et al [7], who proved that the ergodic and outage achievable rate region increase (as sets) monotonically with the singular values of the line-of-sight (LOS) component of the channel matrix. In this contribution we assume that full CSIR but only CDIT is available.…”

Section: Introductionmentioning

confidence: 99%

Asymptotic Ergodic Capacity Region and Rate Optimization of a Multiple Access OFDM MIMO Channel with Separately-Correlated Rician Fading

Riegler

Taricco

2008

IEEE GLOBECOM 2008 - 2008 IEEE Global Telecommunications Conference

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The ergodic capacity region of a multiple access separately-correlated Rician fading multiple input and multiple output (MIMO) wideband channel is investigated by using an asymptotic approach. Our channel model is sufficiently general to allow for considering different spatial correlation matrices for each user and delay at the transmitter and the receiver. We provide two algorithms which can be used to maximize the (weighted) rate sums in order to obtain the ergodic capacity region. Both algorithms are based on an asymptotic approximation of the single-user wideband mutual information. Moreover, it is shown that sum rate maximization is based on waterfilling, similarly to the well known case where the transmitter has perfect channel state information. It is assumed that the number of transmit and receive antennas grows asymptotically approaching finite ratios while the number of users and the signal-to-noise ratios are kept finite. Numerical simulations show that this asymptotic approach is very accurate even when the number of antennas is as low as a few units.

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Monotonicity Results for Coherent MIMO Rician Channels

Cited by 35 publications

References 23 publications

High-SNR Power Offset in Multiantenna Communication

High-SNR Power Offset in Multiantenna Communication

Optimality of beamforming in fading MIMO multiple access channels

Asymptotic Ergodic Capacity Region and Rate Optimization of a Multiple Access OFDM MIMO Channel with Separately-Correlated Rician Fading

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