论文标题

无细胞的MIMO中RIS增强的弹性

RIS-enhanced Resilience in Cell-Free MIMO

论文作者

Weinberger, Kevin, Reifert, Robert-Jeron, Sezgin, Aydin, Basar, Ertugrul

论文摘要

无线网络体系结构实现了越来越多的需要高可靠性和容错性的应用程序,因此最终依靠无线通道,这可能会受到损害和障碍。因此,这些体系结构需要在物理层中制定备份计划,以确保功能,尤其是在涉及与安全相关的方面时。为此,这项工作建议利用可重构的智能表面(RIS)作为抵抗中断的弹性机制。 RIS的优势从它们的固有添加替代通道链接以及其可重构性结合使用。在无单元的多输入和多出输出(MIMO)设置中研究了主要好处,其中直接通道路径受到阻塞。提出了一个优化问题,其中包括带有波束形成和相移配置的速率分配,并通过具有弹性的交替优化方法解决。数值结果表明,即使将随机配置的RI部署到网络上,也会降低由阻塞引起的性能降解。在优化的情况下,这变得更加明显,其中RI可以完全抵消性能降解。有趣的是,由于RIS反射的贡献,即使在不优化的情况下,也为系统敏感系统添加更多的反映元素,即使是时间敏感的系统,也为弹性带来了总体好处。

More and more applications that require high reliability and fault tolerance are realized with wireless network architectures and thus ultimately rely on the wireless channels, which can be subject to impairments and blockages. Hence, these architectures require a backup plan in the physical layer in order to guarantee functionality, especially when safety-relevant aspects are involved. To this end, this work proposes to utilize the reconfigurable intelligent surface (RIS) as a resilience mechanism to counteract outages. The advantages of RISs for such a purpose derive from their inherent addition of alternative channel links in combination with their reconfigurability. The major benefits are investigated in a cell-free multiple-input and multiple-output (MIMO) setting, in which the direct channel paths are subject to blockages. An optimization problem is formulated that includes rate allocation with beamforming and phase shift configuration and is solved with a resilience-aware alternating optimization approach. Numerical results show that deploying even a randomly-configured RIS to a network reduces the performance degradation caused by blockages. This becomes even more pronounced in the optimized case, in which the RIS is able to potentially counteract the performance degradation entirely. Interestingly, adding more reflecting elements to the system brings an overall benefit for the resilience, even for time-sensitive systems, due to the contribution of the RIS reflections, even when unoptimized.

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