RIS-Assisted Survivable Fronthaul Design in Cell-Free Massive MIMO System

Fuente: arXiv
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Autori principali: Li, Zhenyu, Demir, Özlem Tuğfe, Björnson, Emil, Cavdar, Cicek
Natura: Preprint
Pubblicazione: 2025
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author Li, Zhenyu
Demir, Özlem Tuğfe
Björnson, Emil
Cavdar, Cicek
author_facet Li, Zhenyu
Demir, Özlem Tuğfe
Björnson, Emil
Cavdar, Cicek
contents This paper investigates the application of reconfigurable intelligent surfaces (RISs) to improve fronthaul link survivability in cell-free massive MIMO (CF mMIMO) systems. To enhance the fronthaul survivability, two complementary mechanisms are considered. Firstly, RIS is set to provide reliable line-of-sight (LOS) connectivity and enhance the mmWave backup link. Secondly, a resource-sharing scheme that leverages redundant cable capacity through neighboring master access points (APs) to guarantee availability is considered. We formulate the redundant capacity minimization problem as a RIS-assisted multi-user MIMO rate control optimization problem, developing a novel solution that combines a modified weighted minimum mean square error (WMMSE) algorithm for precoding design with Riemannian gradient descent for RIS phase shift optimization. Our numerical evaluations show that RIS reduces the required redundant capacity by 65.6% compared to the no RIS case to reach a 99% survivability. The results show that the most substantial gains of RIS occur during complete outages of the direct disconnected master AP-CPU channel. These results demonstrate RIS's potential to significantly enhance fronthaul reliability while minimizing infrastructure costs in next-generation wireless networks.
format Preprint
id arxiv_https___arxiv_org_abs_2505_19152
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle RIS-Assisted Survivable Fronthaul Design in Cell-Free Massive MIMO System
Li, Zhenyu
Demir, Özlem Tuğfe
Björnson, Emil
Cavdar, Cicek
Information Theory
Signal Processing
This paper investigates the application of reconfigurable intelligent surfaces (RISs) to improve fronthaul link survivability in cell-free massive MIMO (CF mMIMO) systems. To enhance the fronthaul survivability, two complementary mechanisms are considered. Firstly, RIS is set to provide reliable line-of-sight (LOS) connectivity and enhance the mmWave backup link. Secondly, a resource-sharing scheme that leverages redundant cable capacity through neighboring master access points (APs) to guarantee availability is considered. We formulate the redundant capacity minimization problem as a RIS-assisted multi-user MIMO rate control optimization problem, developing a novel solution that combines a modified weighted minimum mean square error (WMMSE) algorithm for precoding design with Riemannian gradient descent for RIS phase shift optimization. Our numerical evaluations show that RIS reduces the required redundant capacity by 65.6% compared to the no RIS case to reach a 99% survivability. The results show that the most substantial gains of RIS occur during complete outages of the direct disconnected master AP-CPU channel. These results demonstrate RIS's potential to significantly enhance fronthaul reliability while minimizing infrastructure costs in next-generation wireless networks.
title RIS-Assisted Survivable Fronthaul Design in Cell-Free Massive MIMO System
topic Information Theory
Signal Processing
url https://arxiv.org/abs/2505.19152