Saturation in two-timescale RIS beamforming
This paper investigates reconfigurable intelligent surface (RIS)-assisted wireless communications under a two-timescale architecture, in which the RIS phase shifts are optimized from long-term channel statistics, eliminating per-element training and thereby slashing channel estimation overhead. It i...
| Autores: | , , |
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| Tipo de recurso: | artículo |
| Estado: | Versión publicada |
| Fecha de publicación: | 2025 |
| País: | España |
| Institución: | Universitat Pompeu Fabra |
| Repositorio: | Repositorio Digital de la UPF |
| OAI Identifier: | oai:dnet:rdupf_______::d2727ede82335155a4df43678c9e8e54 |
| Acceso en línea: | https://hdl.handle.net/10230/73317 http://dx.doi.org/10.1109/OJCOMS.2025.3638874 |
| Access Level: | acceso abierto |
| Palabra clave: | Reconfigurable intelligent surface Beamforming Statistical channel-state information Two-timescale design |
| Sumario: | This paper investigates reconfigurable intelligent surface (RIS)-assisted wireless communications under a two-timescale architecture, in which the RIS phase shifts are optimized from long-term channel statistics, eliminating per-element training and thereby slashing channel estimation overhead. It is shown that, while the power captured by the RIS scales linearly with the number of its elements, the two-timescale beamforming gain upon re-radiation towards the receiver saturates rapidly as the number of RIS elements increases, for a broad class of power angular spectra (PAS). The saturation ceiling depends on the PAS angular decay, which governs how quickly inter-element spatial correlation vanishes. Steeper decays yield stronger correlations and, hence, a higher ceiling. The implications of this saturation on the effectiveness of two-timescale RIS-assisted communications are discussed. |
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