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56
Impact of antenna correlation on the capacity of multiantenna channels
 IEEE TRANS. INFORM. THEORY
, 2005
"... This paper applies random matrix theory to obtain analytical characterizations of the capacity of correlated multiantenna channels. The analysis is not restricted to the popular separable correlation model, but rather it embraces a more general representation that subsumes most of the channel model ..."
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Cited by 103 (6 self)
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This paper applies random matrix theory to obtain analytical characterizations of the capacity of correlated multiantenna channels. The analysis is not restricted to the popular separable correlation model, but rather it embraces a more general representation that subsumes most of the channel models that have been treated in the literature. For arbitrary signaltonoise ratios @ A, the characterization is conducted in the regime of large numbers of antennas. For the low and high regions, in turn, we uncover compact capacity expansions that are valid for arbitrary numbers of antennas and that shed insight on how antenna correlation impacts the tradeoffs among power, bandwidth, and rate.
HighSNR power offset in multiantenna communication
 IEEE Transactions on Information Theory
, 2005
"... Abstract—The analysis of the multipleantenna capacity in the high regime has hitherto focused on the high slope (or maximum multiplexing gain), which quantifies the multiplicative increase as a function of the number of antennas. This traditional characterization is unable to assess the impact of ..."
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Cited by 92 (18 self)
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Abstract—The analysis of the multipleantenna capacity in the high regime has hitherto focused on the high slope (or maximum multiplexing gain), which quantifies the multiplicative increase as a 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 a function of �f, the high capacity is expanded as an affine function where the impact of channel features such as antenna correlation, unfaded components, etc., resides in the zeroorder term or power offset. The power offset, for which we find insightful closedform expressions, is shown to play a chief role for levels of practical interest. Index Terms—Antenna correlation, channel capacity, coherent communication, fading channels, high analysis, multiantenna arrays, Ricean channels.
Multipleantenna capacity in the lowpower regime
 IEEE TRANS. INFORM. THEORY
, 2003
"... This paper provides analytical characterizations of the impact on the multipleantenna capacity of several important features that fall outside the standard multipleantenna model, namely: i) antenna correlation, ii) Ricean factors, iii) polarization diversity, and iv) outofcell interference; all ..."
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Cited by 85 (11 self)
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This paper provides analytical characterizations of the impact on the multipleantenna capacity of several important features that fall outside the standard multipleantenna model, namely: i) antenna correlation, ii) Ricean factors, iii) polarization diversity, and iv) outofcell interference; all in the regime of low signaltonoise ratio. The interplay of rate, bandwidth, and power is analyzed in the region of energy per bit close to its minimum value. The analysis yields practical design lessons for arbitrary number of antennas in the transmit and receive arrays.
Analysis and performance of some basic spacetime architectures
 Selected Areas in Communications, IEEE Journal on
, 2003
"... Abstract—In this paper, we discuss some of the most basic architectural superstructures for wireless links with multiple antennas: at the transmit site and at the receive site. Toward leveraging the gains of the last half century of coding theory, we emphasize those structures that can be composed u ..."
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Cited by 47 (1 self)
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Abstract—In this paper, we discuss some of the most basic architectural superstructures for wireless links with multiple antennas: at the transmit site and at the receive site. Toward leveraging the gains of the last half century of coding theory, we emphasize those structures that can be composed using spatially one dimensional coders and decoders. These structures are investigated primarily under a probability of outage constraint. The random matrix channel is assumed to hold steady for such a large number ofdimensional vector symbol transmission times, that an infinite time horizon Shannon analysis provides useful insights. The resulting extraordinary capacities are contrasted for architectures that differ in the way that they manage selfinterference in the presence of additive receiver noise. A universally optimal architecture with a diagonal space–time layering is treated, as is an architecture with horizontal space–time layering and an architecture with a single outer code. Some capacity asymptotes for large numbers of antennas are also included. Some results for frequency selective channels are presented: It is only necessary to feedback rates, one per transmit antenna, to attain capacity. Also, capacity of an () link is, in a certain sense, invariant with respect to signaling format. Index Terms—Multiple antennas, space–time processing, wireless communications.
Capacity of MIMO Channels: Asymptotic Evaluation Under Correlated Fading
 IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS
, 2003
"... This paper investigates the asymptotic uniform power allocation capacity of frequency nonselective multipleinput multipleoutput channels with fading correlation at either the transmitter or the receiver. We consider the asymptotic situation, where the number of inputs and outputs increase without ..."
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Cited by 36 (1 self)
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This paper investigates the asymptotic uniform power allocation capacity of frequency nonselective multipleinput multipleoutput channels with fading correlation at either the transmitter or the receiver. We consider the asymptotic situation, where the number of inputs and outputs increase without bound at the same rate. A simple uniparametric model for the fading correlation function is proposed and the asymptotic capacity per antenna is derived in closed form. Although the proposed correlation model is introduced only for mathematical convenience, it is shown that its shape is very close to an exponentially decaying correlation function. The asymptotic expression obtained provides a simple and yet useful way of relating the actual fading correlation to the asymptotic capacity per antenna from a purely analytical point of view. For example, the asymptotic expressions indicate that fading correlation is more harmful when arising at the side with less antennas. Moreover, fading correlation does not influence the rate of growth of the asymptotic capacity per receive antenna with high 0 .
Increasing downlink cellular throughput with limited network MIMO coordination
 IEEE Trans. Wireless Commun
, 2009
"... Abstract—Singleuser, multiuser, and network MIMO performance is evaluated for downlink cellular networks with 12 antennas per site, sectorization, universal frequency reuse, scheduled packetdata, and a dense population of stationary users. Compared to a singleuser MIMO baseline system with 3 sec ..."
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Cited by 33 (1 self)
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Abstract—Singleuser, multiuser, and network MIMO performance is evaluated for downlink cellular networks with 12 antennas per site, sectorization, universal frequency reuse, scheduled packetdata, and a dense population of stationary users. Compared to a singleuser MIMO baseline system with 3 sectors per site, network MIMO coordination is found to increase throughput by a factor of 1.8 with intrasite coordination among antennas belonging to the same cell site. Intrasite coordination performs almost as well as a highly sectorized system with 12 sectors per site. Increasing the coordination cluster size from 1 to 7 sites increases the throughput gain factor to 2.5. Index Terms—MIMO, capacity, broadcast channel, multiuser systems, simulations, cellular networks. I.
On the Outage Capacity of Correlated MultiplePath MIMO Channels
, 2005
"... The use of multiantenna arrays in both transmission and reception has been shown to dramatically increase the throughput of wireless communication systems. As a result there has been considerable interest in characterizing the ergodic average of the mutual information for realistic correlated chan ..."
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Cited by 25 (1 self)
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The use of multiantenna arrays in both transmission and reception has been shown to dramatically increase the throughput of wireless communication systems. As a result there has been considerable interest in characterizing the ergodic average of the mutual information for realistic correlated channels. Here, an approach is presented that provides analytic expressions not only for the average, but also the higher cumulant moments of the distribution of the mutual information for zeromean Gaussian MIMO channels with the most general multipath covariance matrices when the channel is known at the receiver. These channels include multitap delay paths, as well as general channels with covariance matrices that cannot be written as a Kronecker product, such as dualpolarized antenna arrays with general correlations at both transmitter and receiver ends. The mathematical methods are formally valid for large antenna numbers, in which limit it is shown that all higher cumulant moments of the distribution, other than the first two scale to zero. Thus, it is confirmed that the distribution of the mutual information tends to a Gaussian, which enables one to calculate the outage capacity. These results are quite accurate even in the case of a few antennas, which makes this approach applicable to realistic situations.
Capacityapproaching rate function for layered multiantenna architectures
 IEEE Trans. Wireless Commun
, 2003
"... Abstract—The simultaneous use of multiple transmit and receive antennas can unleash very large capacity increases in rich multipath environments. Although such capacities can be approached by layered multiantenna architectures with perantenna rate control, the need for shortterm feedback arises as ..."
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Cited by 9 (4 self)
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Abstract—The simultaneous use of multiple transmit and receive antennas can unleash very large capacity increases in rich multipath environments. Although such capacities can be approached by layered multiantenna architectures with perantenna rate control, the need for shortterm feedback arises as a potential impediment, in particular as the number of antennas—and, thus, the number of rates to be controlled—increases. What we show, however, is that the need for shortterm feedback in fact vanishes as the number of antennas and/or the diversity order increases. Specifically, the rate supported by each transmit antenna becomes deterministic and a sole function of the signaltonoise, the ratio of transmit and receive antennas, and the decoding order, all of which are either fixed or slowly varying. More generally, we illustrate—through this specific derivation—the relevance of some established random codedivision multipleaccess results to the singleuser multiantenna problem. Index Terms—Adaptive arrays, antenna diversity, channel capacity, fading channels, multipleantenna information theory, multiuser detection. I.
GRASSMANNIAN DIFFERENTIAL LIMITED FEEDBACK FOR INTERFERENCE ALIGNMENT
, 2011
"... Interference alignment (IA) can use channel state information (CSI) to precode, align, and reduce the dimension of interference at each of the receivers, enabling systems to achieve their maximum multiplexing gain. CSI, estimated at the receivers, can be shared with the transmitters by limited feedb ..."
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Cited by 8 (3 self)
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Interference alignment (IA) can use channel state information (CSI) to precode, align, and reduce the dimension of interference at each of the receivers, enabling systems to achieve their maximum multiplexing gain. CSI, estimated at the receivers, can be shared with the transmitters by limited feedback. The number of channels to be shared grows with the square of the number of users creating too much overhead in conventional feedback methods. This paper proposes Grassmannian differential feedback to take advantage of temporal correlation in the channel and reduce overhead. Grassmannian differential feedback uses two manifold tools, tangent spaces and geodesic paths, to track the evolution of CSI on the manifold. Simulation results show that the proposed feedback strategy allows IA to perform well over a wide range of Doppler spreads, and to approach perfect CSI performance in slowly varying channels. 1.
Large n analysis of amplifyandforward MIMO relay channels with correlated Rayleigh fading
 IEEE Trans. Inform. Theory
, 2008
"... In this correspondence the cumulants of the mutual information of the flat Rayleigh fading amplifyandforward MIMO relay channel without direct link between source and destination are derived in the large array limit. The analysis is based on the replica trick and covers both spatially independent ..."
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Cited by 8 (0 self)
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In this correspondence the cumulants of the mutual information of the flat Rayleigh fading amplifyandforward MIMO relay channel without direct link between source and destination are derived in the large array limit. The analysis is based on the replica trick and covers both spatially independent and correlated fading in the first and the second hop, while beamforming at all terminals is restricted to deterministic weight matrices. Expressions for mean and variance of the mutual information are obtained. Their parameters are determined by a nonlinear equation system. All higher cumulants are shown to vanish as the number of antennas n goes to infinity. In conclusion the distribution of the mutual information I becomes Gaussian in the large n limit and is completely characterized by the expressions obtained for mean and variance of I. Comparisons with simulation results show that the asymptotic results serve as excellent approximations for systems with only few antennas at each node. The derivation of the results follows the technique formalized by Moustakas et al. in [1]. Although the evaluations are more involved for the MIMO relay channel compared to pointtopoint MIMO channels, the structure of the results is surprisingly simple again. In particular an elegant formula for the mean of the mutual information is obtained, i.e., the ergodic capacity of the twohop amplifyandforward MIMO relay channel without direct link. Index Terms MIMO relay channel, amplifyandforward, replica analysis, random matrix theory, large antenna number limit, cumulants of mutual information, correlated channels. I.