248 research outputs found
Spectral Efficiency Analysis of Multi-Cell Massive MIMO Systems with Ricean Fading
This paper investigates the spectral efficiency of multi-cell massive
multiple-input multiple-output systems with Ricean fading that utilize the
linear maximal-ratio combining detector. We firstly present closed-form
expressions for the effective signal-to-interference-plus-noise ratio (SINR)
with the least squares and minimum mean squared error (MMSE) estimation
methods, respectively, which apply for any number of base-station antennas
and any Ricean -factor. Also, the obtained results can be particularized in
Rayleigh fading conditions when the Ricean -factor is equal to zero. In the
following, novel exact asymptotic expressions of the effective SINR are derived
in the high and high Ricean -factor regimes. The corresponding analysis
shows that pilot contamination is removed by the MMSE estimator when we
consider both infinite and infinite Ricean -factor, while the pilot
contamination phenomenon persists for the rest of cases. All the theoretical
results are verified via Monte-Carlo simulations.Comment: 15 pages, 2 figures, the tenth International Conference on Wireless
Communications and Signal Processing (WCSP 2018), to appea
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
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
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