Hybrid RIS With Sub-Connected Active Partitions: Performance Analysis and Transmission Design

hybrid RIS; optimization; performance analysis; Reconfigurable intelligent surface (RIS); sub-connected RIS; Hybrid reconfigurable intelligent surface; Optimisations; Performances analysis; Power; Reconfigurable; Reconfigurable intelligent surface; Sub-connected reconfigurable intelligent surface; Sub-surfaces; Computer Science Applications; Electrical and Electronic Engineering; Applied Mathematics; Reconfigurable intelligent surfaces; Power amplifiers; MISO; Array signal processing; Hybrid power systems; Downlink; Receivers; Signal to noise ratio; Power demand

Abstract :

[en] The emerging reconfigurable intelligent surface (RIS) technology promises to enhance network capacity via passive reflect beamforming. However, product path loss limits its performance gains. Fully-connected (FC) active RIS integrates a reflect-type power amplifier into each element to address this issue, while sub-connected (SC) active RIS, which employs partitioning and power amplifier sharing per partition, and hybrid FC-active/passive RIS utilize fewer power amplifiers to tackle the resulting cost and energy consumption challenges. This study introduces novel hybrid RIS structures with at least one SC-active reflecting sub-surface (RS) to achieve a better capacity/energy efficiency (EE) balance. A system model considering power amplifier sharing and resulting in a proper diagonal SC-active RIS/RS beamforming matrix is derived for the first time. The asymptotic signal-to-noise-ratio of active/passive and active/active RIS with a single shared power amplifier per active RS in a single-user single-input single-output setup is analyzed. The transmit and RIS beamforming weights are jointly optimized to maximize the EE of a hybrid RIS-aided multi-user multiple-input single-output downlink system under the power consumption constraints of the base station and the RIS. Numerical results highlight the substantial performance gains of the proposed designs over benchmarks and provide insights.

Disciplines :

Computer science

Author, co-author :

Ntougias, Konstantinos ; University of Cyprus, Department of Electrical and Computer Engineering, Nicosia, Cyprus

CHATZINOTAS, Symeon ; University of Luxembourg > Interdisciplinary Centre for Security, Reliability and Trust (SNT) > SigCom ; Kyung Hee University, College of Electronics & Information, Yongin-si, South Korea

Krikidis, Ioannis ; University of Cyprus, Department of Electrical and Computer Engineering, Nicosia, Cyprus

External co-authors :

yes

Language :

English

Title :

Hybrid RIS With Sub-Connected Active Partitions: Performance Analysis and Transmission Design

Publication date :

03 April 2025

Journal title :

IEEE Transactions on Wireless Communications

ISSN :

1536-1276

eISSN :

1558-2248

Publisher :

Institute of Electrical and Electronics Engineers Inc.

Volume :

Issue :

Pages :

6705 - 6721

Peer reviewed :

Peer Reviewed verified by ORBi

Additional URL :

http://xplorestaging.ieee.org/ielx8/7693/11124333/10948577.pdf?arnumber=10948577

Funders :

European Research Council (ERC) under European Union’s Horizon 2020 Research and Innovation Programme
Cyprus Research and Innovation Foundation
European Union’s HORIZON Programme under iSEE-6G

Funding text :

This work was supported in part by European Research Council (ERC) under European Union\u2019s Horizon 2020 Research and Innovation Programme under Grant 819819, in part by Cyprus Research and Innovation Foundation under Grant DUAL USE/0922/0031, and in part by European Union\u2019s HORIZON Programme under iSEE-6G under Grant 10113929.

Available on ORBilu :

since 14 November 2025

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