On the Capacity of Large-MIMO Block-Fading Channels
Artikel i vetenskaplig tidskrift, 2013

We characterize the capacity of Rayleigh block-fading multiple-input multiple-output (MIMO) channels in the noncoherent setting where transmitter and receiver have no a priori knowledge of the realizations of the fading channel. We prove that unitary space-time modulation (USTM) is not capacity-achieving in the high signal-to-noise ratio (SNR) regime when the total number of antennas exceeds the coherence time of the fading channel (expressed in multiples of the symbol duration), a situation that is relevant for MIMO systems with large antenna arrays (large-MIMO systems). This result settles a conjecture by Zheng & Tse (2002) in the affirmative. The capacity-achieving input signal, which we refer to as Beta-variate space-time modulation (BSTM), turns out to be the product of a unitary isotropically distributed random matrix, and a diagonal matrix whose nonzero entries are distributed as the square-root of the eigenvalues of a Beta-distributed random matrix of appropriate size. Numerical results illustrate that using BSTM instead of USTM in large-MIMO systems yields a rate gain as large as 13% for SNR values of practical interest.

noncoherent setting

large-MIMO systems

ergodic capacity

Block-fading channel


Wei Yang

Signaler och system, Kommunikationssystem, informationsteori och antenner, Kommunikationssystem

Giuseppe Durisi

Signaler och system, Kommunikationssystem, informationsteori och antenner, Kommunikationssystem

Erwin Riegler

Technische Universität Wien

IEEE Journal on Selected Areas in Communications

0733-8716 (ISSN)

Vol. 31 117-132 6415385


Informations- och kommunikationsteknik