Clustered Robust Linear Precoding for Cell-Free MU-MIMO Systems

Precoding techniques are key to dealing with multiuser interference in the downlink of cell-free (CF) multiple-input multiple-output systems. However, these techniques rely on accurate estimates of the channel state information at the transmitter (CSIT), which is not possible to obtain in practical...

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Bibliographic Details
Published in:2024 27th International Workshop on Smart Antennas (WSA) pp. 1 - 6
Main Authors: Flores, Andre R., de Lamare, Rodrigo C., Mishra, Kumar Vijay
Format: Conference Proceeding
Language:English
Published: IEEE 17.03.2024
Subjects:
Cell-free wireless networks
cluster precoders
Conferences
Interference
Loading
Mean square error methods
MIMO
multiuser interference
Precoding
robust precoding
Transmitters
Wireless communication
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Summary:Precoding techniques are key to dealing with multiuser interference in the downlink of cell-free (CF) multiple-input multiple-output systems. However, these techniques rely on accurate estimates of the channel state information at the transmitter (CSIT), which is not possible to obtain in practical systems. As a result, precoders cannot handle interference as expected and the residual interference substantially degrades the performance of the system. To address this problem, CF systems require precoders that are robust to CSIT imperfections. In this paper, we propose novel robust precoding techniques to mitigate the effects of residual multiuser interference. To this end, we include a loading term that minimizes the effects of the imperfect CSIT in the optimization objective. We further derive robust precoders that employ clusters of users and access points to reduce the computational cost and the signaling load. Numerical examples show that the proposed robust minimum mean-square error (MMSE) precoding techniques outperform the conventional MMSE precoder for various accuracy levels of CSIT estimates.
DOI:10.1109/WSA61681.2024.10511439