520 research outputs found
Asymptotic analysis of downlink MIMO systems over Rician fading channels
In this work, we focus on the ergodic sum rate in the downlink of a
single-cell large-scale multi-user MIMO system in which the base station
employs N antennas to communicate with single-antenna user equipments. A
regularized zero-forcing (RZF) scheme is used for precoding under the
assumption that each link forms a spatially correlated MIMO Rician fading
channel. The analysis is conducted assuming and grow large with a non
trivial ratio and perfect channel state information is available at the base
station. Recent results from random matrix theory and large system analysis are
used to compute an asymptotic expression of the signal-to-interference-
plus-noise ratio as a function of the system parameters, the spatial
correlation matrix and the Rician factor. Numerical results are used to
evaluate the performance gap in the finite system regime under different
operating conditions.Comment: 5 pages, 2 figures. Published at the 41st IEEE International
Conference on Acoustics, Speech and Signal Processing (ICASSP 2016),
Shanghai, 20-25 March 201
Asymptotic Analysis of Multicell Massive MIMO over Rician Fading Channels
This work considers the downlink of a multicell massive MIMO system in which
base stations (BSs) of antennas each communicate with
single-antenna user equipments randomly positioned in the coverage area. Within
this setting, we are interested in evaluating the sum rate of the system when
MRT and RZF are employed under the assumption that each intracell link forms a
MIMO Rician fading channel. The analysis is conducted assuming that and
grow large with a non-trivial ratio under the assumption that the data
transmission in each cell is affected by channel estimation errors, pilot
contamination, and an arbitrary large scale attenuation. Numerical results are
used to validate the asymptotic analysis in the finite system regime and to
evaluate the network performance under different settings. The asymptotic
results are also instrumental to get insights into the interplay among system
parameters.Comment: 7 pages, 2 figures, submitted to GLOBECOM16, Washington, DC USA.
arXiv admin note: text overlap with arXiv:1601.0702
Cell-Free Massive MIMO with Multi-Antenna Users over Weichselberger Rician Channels
We consider a cell-free massive multiple-input multiple-output (MIMO) system
with multi-antenna access points and user equipments (UEs) over Weichselberger
Rician fading channels with random phase-shifts. More specifically, we
investigate the uplink spectral efficiency (SE) for two pragmatic processing
schemes: 1) the fully centralized processing scheme with global minimum mean
square error (MMSE) or maximum ratio (MR) combining; 2) the large-scale fading
decoding (LSFD) scheme with local MMSE or MR combining. To improve the system
SE performance, we propose a practical uplink precoding scheme based on only
the eigenbasis of the UE-side correlation matrices. Moreover, we derive novel
closed-form SE expressions for characterizing the LSFD scheme with the MR
combining. Numerical results validate the accuracy of our derived expressions
and show that the proposed precoding scheme can significantly improve the SE
performance compared with the scenario without any precoding scheme.Comment: 14 pages, 5 figures, to appear in IEEE Transactions on Vehicular
Technolog
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