Unlocking the Potential of Local CSI in Cell-Free Networks with Channel Aging and Fronthaul Delays

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Autori principali: Miretti, Lorenzo, Stańczak, Sławomir
Natura: Preprint
Pubblicazione: 2024
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author Miretti, Lorenzo
Stańczak, Sławomir
author_facet Miretti, Lorenzo
Stańczak, Sławomir
contents It is generally believed that downlink cell-free networks perform best under centralized implementations where the local channel state information (CSI) acquired by the access-points (AP) is forwarded to one or more central processing units (CPU) for the computation of the joint precoders based on global CSI. However, mostly due to limited fronthaul capabilities, this procedure incurs some delay that may lead to partially outdated precoding decisions and hence performance degradation. In some scenarios, this may even lead to worse performance than distributed implementations where the precoders are locally computed by the APs based on partial yet timely local CSI. To address this issue, this study considers the problem of robust precoding design merging the benefits of timely local CSI and delayed global CSI. As main result, we provide a novel distributed precoding design based on the recently proposed team minimum mean-square error method. As a byproduct, we also obtain novel insights related to the AP-CPU functional split problem. Our main conclusion, corroborated by simulations, is that the opportunity of performing some local precoding computations at the APs should not be neglected, even in centralized implementations.
format Preprint
id arxiv_https___arxiv_org_abs_2404_12786
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Unlocking the Potential of Local CSI in Cell-Free Networks with Channel Aging and Fronthaul Delays
Miretti, Lorenzo
Stańczak, Sławomir
Information Theory
Signal Processing
It is generally believed that downlink cell-free networks perform best under centralized implementations where the local channel state information (CSI) acquired by the access-points (AP) is forwarded to one or more central processing units (CPU) for the computation of the joint precoders based on global CSI. However, mostly due to limited fronthaul capabilities, this procedure incurs some delay that may lead to partially outdated precoding decisions and hence performance degradation. In some scenarios, this may even lead to worse performance than distributed implementations where the precoders are locally computed by the APs based on partial yet timely local CSI. To address this issue, this study considers the problem of robust precoding design merging the benefits of timely local CSI and delayed global CSI. As main result, we provide a novel distributed precoding design based on the recently proposed team minimum mean-square error method. As a byproduct, we also obtain novel insights related to the AP-CPU functional split problem. Our main conclusion, corroborated by simulations, is that the opportunity of performing some local precoding computations at the APs should not be neglected, even in centralized implementations.
title Unlocking the Potential of Local CSI in Cell-Free Networks with Channel Aging and Fronthaul Delays
topic Information Theory
Signal Processing
url https://arxiv.org/abs/2404.12786