252,699 research outputs found
Trade-off between complexity and BER performance of a polynomial SVD-based broadband MIMO transceiver
In this paper we investigate non-linear precoding solutions for the problem of broadband multiple-input multiple output(MIMO) systems. Based on a polynomial singular value decomposition (PSVD) we can decouple a broadband MIMO channel into independent dispersive spectrally majorised single-input single-output (SISO) subchannels. In this contribution, the focus of our work is to explore the influence of approximations on the PSVD, and the performance degradation that can be expected as a result
Multi-dimensional Gaussian fluctuations on the Poisson space
We study multi-dimensional normal approximations on the Poisson space by
means of Malliavin calculus, Stein's method and probabilistic interpolations.
Our results yield new multi-dimensional central limit theorems for multiple
integrals with respect to Poisson measures -- thus significantly extending
previous works by Peccati, Sol\'e, Taqqu and Utzet. Several explicit examples
(including in particular vectors of linear and non-linear functionals of
Ornstein-Uhlenbeck L\'evy processes) are discussed in detail.Comment: 40 page
Extended 1D Method for Coherent Synchrotron Radiation including Shielding
Coherent Synchrotron Radiation can severely limit the performance of
accelerators designed for high brightness and short bunch length. Examples
include light sources based on ERLs or FELs, and bunch compressors for linear
colliders. In order to better simulate Coherent Synchrotron Radiation, the
established 1-dimensional formalism is extended to work at lower energies, at
shorter bunch lengths, and for an arbitrary configuration of multiple bends.
Wide vacuum chambers are simulated by means of vertical image charges. This
formalism has been implemented in the general beam dynamics code "Bmad" and its
results are here compared to analytical approximations, to numerical solutions
of the Maxwell equations, and to the simulation code "elegant"
Large System Analysis of Power Normalization Techniques in Massive MIMO
Linear precoding has been widely studied in the context of Massive
multiple-input-multiple-output (MIMO) together with two common power
normalization techniques, namely, matrix normalization (MN) and vector
normalization (VN). Despite this, their effect on the performance of Massive
MIMO systems has not been thoroughly studied yet. The aim of this paper is to
fulfill this gap by using large system analysis. Considering a system model
that accounts for channel estimation, pilot contamination, arbitrary pathloss,
and per-user channel correlation, we compute tight approximations for the
signal-to-interference-plus-noise ratio and the rate of each user equipment in
the system while employing maximum ratio transmission (MRT), zero forcing (ZF),
and regularized ZF precoding under both MN and VN techniques. Such
approximations are used to analytically reveal how the choice of power
normalization affects the performance of MRT and ZF under uncorrelated fading
channels. It turns out that ZF with VN resembles a sum rate maximizer while it
provides a notion of fairness under MN. Numerical results are used to validate
the accuracy of the asymptotic analysis and to show that in Massive MIMO,
non-coherent interference and noise, rather than pilot contamination, are often
the major limiting factors of the considered precoding schemes.Comment: 12 pages, 3 figures, Accepted for publication in the IEEE
Transactions on Vehicular Technolog
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