Abstract—The analysis of the multiple-antenna 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 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 levels of practical interest. Index Terms—Antenna correlation, channel capacity, coherent communication, fading channels, high- analysis, multiantenna arrays, Ricean channels.

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 signal-to-noise 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.

The dramatic linear increase in ergodic capacity with the number of antennas promised by MIMO wireless communication systems is based on idealized channel models representing a rich scattering environment. Is such scaling sustainable in realistic scattering scenarios? Existing physical models, although realistic, are intractable for addressing this problem analytically due to their complicated nonlinear dependence on propagation path parameters, such as the angles of arrival and delays. In this paper, we leverage a recently introduced virtual representation of physical models that is essentially a Fourier series representation of wideband MIMO channels in terms of fixed virtual angles and delays. Motivated by physical considerations, we propose a -connected model for correlated channels defined by a virtual spatial channel matrix consisting of non-vanishing diagonals with i.i.d. Gaussian entries. The parameter provides a meaningful and tractable measure of the richness of scattering. We derive general bounds for the coherent ergodic capacity and investigate capacity scaling with the number of antennas and bandwidth. In the large antenna regime, we show that linear capacity scaling is possible if scales linearly with the number of antennas. This, in turn, is possible if the number of resolvable paths grows quadratically with the number of antennas. The capacity saturates for linear growth in the number of paths (fixed ). The ergodic capacity does not depend on frequency selectivity of the channel in the wideband case. Increasing bandwidth tightens the bounds and hastens the convergence of scaling behavior. For large bandwidth, the capacity scales linearly with SNR as well. We also provide an explicit characterization of the wideband slope recently proposed by Verdu. Nume...

Abstract — We characterize the capacity-achieving input covariance for multi-antenna channels known instantaneously at the receiver and in distribution at the transmitter. Our characterization, valid for arbitrary numbers of antennas, encompasses both the eigenvectors and the eigenvalues. The eigenvectors are found for zero-mean channels with arbitrary fading profiles and a wide range of correlation and keyhole structures. For the eigenvalues, in turn, we present necessary and sufficient conditions as well as an iterative algorithm that exhibits remarkable properties: universal applicability, robustness and rapid convergence. In addition, we identify channel structures for which an isotropic input achieves capacity. Index Terms — Capacity, MIMO, input optimization, fading, antenna correlation, Ricean fading, keyhole channel.

Abstract — A unified framework for coherent multiple antenna communications is presented leading to a general space-time code design criterion valid for arbitrary spatial and temporal fading correlations. This framework provides insights into the effect of each of spatial and temporal correlations on spacetime code design. The single code design expression applies to quasi-static, fast fading and multiple block fading channels and more generally also to channels with arbitrary correlations in the temporal dimension as well as in the spatial dimension with arbitrary rank. The general coding strategy proposed consists of precoding a space-time code with its size determined by the rank of transmit correlation, the structure determined by the Cholesky factorization of the temporal correlation, and the precoding matrix obtained from the eigenvectors of the transmit correlation matrix. Index Terms — Antenna diversity, correlated fading, error analysis, MIMO-OFDM, signal design, space-time modulation,