1,375 research outputs found
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
Multi-Point Integrated Sensing and Communication: Fusion Model and Functionality Selection
Integrated sensing and communication (ISAC) represents a paradigm shift,
where previously competing wireless transmissions are jointly designed to
operate in harmony via the shared use of the hardware platform for improving
the spectral and energy efficiencies. However, due to adversarial factors such
as fading and interference, ISAC may suffer from high sensing uncertainties.
This paper presents a multi-point ISAC (MPISAC) system that fuses the outputs
from multiple ISAC devices for achieving higher sensing performance by
exploiting multi-view data redundancy. Furthermore, we propose to effectively
explore the performance trade-off between sensing and communication via a
functionality selection module that adaptively determines the working state
(i.e., sensing or communication) of an ISAC device. The crux of our approach is
to derive a fusion model that predicts the fusion accuracy via hypothesis
testing and optimal voting analysis. Simulation results demonstrate the
superiority of MPISAC over various benchmark schemes and show that the proposed
approach can effectively span the trade-off region in ISAC systems.Comment: 7 pages, 4 figures, to appear in IEEE Wireless Communications Letter
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