13,938 research outputs found
Delay Constrained Throughput Analysis of a Correlated MIMO Wireless Channel
The maximum traffic arrival rate at the network for a given delay guarantee
(delay constrained throughput) has been well studied for wired channels.
However, few results are available for wireless channels, especially when
multiple antennas are employed at the transmitter and receiver. In this work,
we analyze the network delay constrained throughput of a multiple input
multiple output (MIMO) wireless channel with time-varying spatial correlation.
The MIMO channel is modeled via its virtual representation, where the
individual spatial paths between the antenna pairs are Gilbert-Elliot channels.
The whole system is then described by a K-State Markov chain, where K depends
upon the degree of freedom (DOF) of the channel. We prove that the DOF based
modeling is indeed accurate. Furthermore, we study the impact of the delay
requirements at the network layer, violation probability and the number of
antennas on the throughput under different fading speeds and signal strength.Comment: Submitted to ICCCN 2011, 8 pages, 5 figure
Outage Probability and Outage-Based Robust Beamforming for MIMO Interference Channels with Imperfect Channel State Information
In this paper, the outage probability and outage-based beam design for
multiple-input multiple-output (MIMO) interference channels are considered.
First, closed-form expressions for the outage probability in MIMO interference
channels are derived under the assumption of Gaussian-distributed channel state
information (CSI) error, and the asymptotic behavior of the outage probability
as a function of several system parameters is examined by using the Chernoff
bound. It is shown that the outage probability decreases exponentially with
respect to the quality of CSI measured by the inverse of the mean square error
of CSI. Second, based on the derived outage probability expressions, an
iterative beam design algorithm for maximizing the sum outage rate is proposed.
Numerical results show that the proposed beam design algorithm yields better
sum outage rate performance than conventional algorithms such as interference
alignment developed under the assumption of perfect CSI.Comment: 41 pages, 14 figures. accepted to IEEE Transactions on Wireless
Communication
Asymptotic Mutual Information Statistics of Separately-Correlated Rician Fading MIMO Channels
Precise characterization of the mutual information of MIMO systems is
required to assess the throughput of wireless communication channels in the
presence of Rician fading and spatial correlation. Here, we present an
asymptotic approach allowing to approximate the distribution of the mutual
information as a Gaussian distribution in order to provide both the average
achievable rate and the outage probability. More precisely, the mean and
variance of the mutual information of the separatelycorrelated Rician fading
MIMO channel are derived when the number of transmit and receive antennas grows
asymptotically large and their ratio approaches a finite constant. The
derivation is based on the replica method, an asymptotic technique widely used
in theoretical physics and, more recently, in the performance analysis of
communication (CDMA and MIMO) systems. The replica method allows to analyze
very difficult system cases in a comparatively simple way though some authors
pointed out that its assumptions are not always rigorous. Being aware of this,
we underline the key assumptions made in this setting, quite similar to the
assumptions made in the technical literature using the replica method in their
asymptotic analyses. As far as concerns the convergence of the mutual
information to the Gaussian distribution, it is shown that it holds under some
mild technical conditions, which are tantamount to assuming that the spatial
correlation structure has no asymptotically dominant eigenmodes. The accuracy
of the asymptotic approach is assessed by providing a sizeable number of
numerical results. It is shown that the approximation is very accurate in a
wide variety of system settings even when the number of transmit and receive
antennas is as small as a few units.Comment: - submitted to the IEEE Transactions on Information Theory on Nov.
19, 2006 - revised and submitted to the IEEE Transactions on Information
Theory on Dec. 19, 200
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