Large Gain Degradation of Reflective Intelligent Surfaces in Realistic Environments

Dmitry Chizhik; Jinfeng Du

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arXiv · 2605.04354

Large Gain Degradation of Reflective Intelligent Surfaces in Realistic Environments

Dmitry Chizhik·Jinfeng Du

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Abstract

Reflective Intelligent Surfaces (RIS) are considered promising in improving coverage in Non-Line of Sight (NLOS) wireless links, especially at mm wave or higher frequency bands. Coverage provided by RIS is here compared to coverage from such ambient propagation mechanisms as scattering from street poles (e.g. lampposts), and corner diffraction. A simple formula for RIS gain degradation due to channel angle spread is derived. It is found an ideal 0.3 m x 0.3 m RIS at 28 GHz promises to deliver only about 5 dB more power at 200 m around an urban street corner than the ambient scatter already there. Consideration of angle spread brings about some 14 dB drop in RIS power, bringing it well below ambient mechanisms. A 1 m x 1 m RIS at 28 GHz, offers under 2 dB advantage over ambient scatter after including the 25 dB gain degradation due to angle spread. This raises questions about usefulness of RIS-assisted coverage extension in realistic environments.

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BibTeX RIS

Dmitry Chizhik, Jinfeng Du. 2026-05-05. Large Gain Degradation of Reflective Intelligent Surfaces in Realistic Environments. https://arxiv.org/abs/2605.04354

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