Spectral-energy efficiency tradeoff of nearly-passive RIS in MIMO URLLC downlink: diagonal vs. beyond diagonal
This letter investigates the spectral and energy efficiency (EE) tradeoff of nearly-passive (NP) reconfigurable intelligent surfaces (RIS). Locally and globally NP (GNP) RIS are analyzed, considering diagonal and beyond-diagonal (BD) implementations in multi-user multiple-input multiple-output (MU-M...
| Autores: | , , , , |
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| Tipo de recurso: | artículo |
| Fecha de publicación: | 2026 |
| País: | España |
| Institución: | Universidad de Cantabria (UC) |
| Repositorio: | UCrea Repositorio Abierto de la Universidad de Cantabria |
| Idioma: | inglés |
| OAI Identifier: | oai:repositorio.unican.es:10902/39058 |
| Acceso en línea: | https://hdl.handle.net/10902/39058 |
| Access Level: | acceso abierto |
| Palabra clave: | Finite block length coding Low latency Max-min energy efficiency Max-min rate MIMO systems Reconfigurable intelligent surface Ultra-reliable communications |
| Sumario: | This letter investigates the spectral and energy efficiency (EE) tradeoff of nearly-passive (NP) reconfigurable intelligent surfaces (RIS). Locally and globally NP (GNP) RIS are analyzed, considering diagonal and beyond-diagonal (BD) implementations in multi-user multiple-input multiple-output (MU-MIMO) broadcast channels designed for ultra-reliable low-latency communication (URLLC). We demonstrate that all RIS architectures enhance the spectral efficiency with GNP BD-RIS achieving the highest gains. However, its EE is highly sensitive to the static circuit power consumption, since BD-RIS has many more circuit elements than diagonal architectures. Furthermore, we demonstrate that the benefits of BD-RIS over diagonal RIS diminish as the number of data streams per user increases due to the enhanced channel diversity in MIMO systems. |
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