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Active Reconfigurable Intelligent Surfaces (RIS) are a promising technology for 6G wireless networks. This paper investigates a novel hybrid deep reinforcement learning (DRL) framework for resource allocation in a multi-user uplink system…

Signal Processing · Electrical Eng. & Systems 2025-12-29 Mohamed Shalma , Engy Aly Maher , Ahmed El-Mahdy

This paper studies the interference broadcast channel comprising multiple multi-antenna Base Stations (BSs), each controlling a beyond diagonal Reconfigurable Intelligent Surface (RIS) and serving multiple single-antenna users. Wideband…

Information Theory · Computer Science 2024-09-09 Konstantinos D. Katsanos , Paolo Di Lorenzo , George C. Alexandropoulos

This paper introduces a novel method to enhance the connectivity of multi-reconfigurable intelligent surface-assisted device-to-device networks, referred to as multi-RIS-assisted D2D networks, through a unique phase shift determination. The…

Information Theory · Computer Science 2024-10-08 Mohammed Saif , Mohammad Javad-Kalbasi , Shahrokh Valaee

Cell-Free Massive multiple-input multiple-output (MIMO) and reconfigurable intelligent surface (RIS) are two promising technologies for application to beyond-5G networks. This paper considers Cell-Free Massive MIMO systems with the…

Information Theory · Computer Science 2021-12-20 Trinh Van Chien , Hien Quoc Ngo , Symeon Chatzinotas , Marco Di Renzo , Björn Ottersten

We introduce a novel deep reinforcement learning (DRL) approach to jointly optimize transmit beamforming and reconfigurable intelligent surface (RIS) phase shifts in a multiuser multiple input single output (MU-MISO) system to maximize the…

Networking and Internet Architecture · Computer Science 2023-03-30 Baturay Saglam , Doga Gurgunoglu , Suleyman S. Kozat

This work studies a low-complexity design for reconfigurable intelligent surface (RIS)-aided multiuser multiple-input multiple-output systems. The base station (BS) applies receive antenna selection to connect a subset of its antennas to…

Signal Processing · Electrical Eng. & Systems 2022-12-29 Chongjun Ouyang , Ali Bereyhi , Saba Asaad , Ralf R. Müller , Hongwen Yang

Reconfigurable Intelligent Surfaces (RIS) represent a transformative technology for sixth-generation (6G) wireless communications, but it suffers from a significant limitation, namely the double-fading attenuation. Active RIS has emerged as…

Information Theory · Computer Science 2025-04-23 Yang Cao , Wenchi Cheng , Jingqing Wang , Wei Zhang

Active reconfigurable intelligent surfaces (RISs) can improve the performance of integrated sensing and communication (ISAC), and therefore enable simultaneous data transmission and target sensing. However, when the line-of-sight (LoS) link…

Signal Processing · Electrical Eng. & Systems 2024-10-17 Ahmed Magbool , Vaibhav Kumar , Mark F. Flanagan

As an important algorithm in deep reinforcement learning, advantage actor critic (A2C) has been widely succeeded in both discrete and continuous control tasks with raw pixel inputs, but its sample efficiency still needs to improve more. In…

Machine Learning · Computer Science 2022-02-15 Yuan Wang , Chunyuan Zhang , Tianzong Yu , Meng Ma

Reconfigurable intelligent surfaces (RISs) represent a new technology that can shape the radio wave propagation and thus offers a great variety of possible performance and implementation gains. Motivated by this, we investigate the…

Information Theory · Computer Science 2023-02-08 Nemanja Stefan Perović , Le-Nam Tran , Marco Di Renzo , Mark F. Flanagan

The objective of this paper is to evaluate the effectiveness of a two-timescale transmission design in cell-free massive multi-input multiple-output (MIMO) systems incorporating reconfigurable intelligent surfaces (RISs) under the…

Signal Processing · Electrical Eng. & Systems 2023-04-06 Mahdi Eskandari , Kangda Zhi , Huiling Zhu , Cunhua Pan , Jiangzhou Wang

This work considers a reconfigurable intelligent surface (RIS)-aided cell-free massive multiple-input multiple-output (MIMO) system with RIS spatial correlation and electromagnetic interference (EMI). We propose a two-phase channel…

Information Theory · Computer Science 2024-11-18 Jun Qian , Chi Zhang , Khaled B. Letaief , Ross Murch

Reconfigurable intelligent surface (RIS) is a revolutionary technology for sixth-generation (6G) networks owing to its ability to manipulate wireless environments. As a frequency-selective device, RIS can only effectively shape the…

Information Theory · Computer Science 2022-11-01 Sifan Liu , Rang Liu , Ming Li , Yang Liu , Qian Liu

This paper studies the beamforming optimization challenge in reconfigurable intelligent surface (RIS)-aided multiple-input single-output (MISO) systems, where the RIS phase configuration is discrete. Conventional optimization methods for…

Signal Processing · Electrical Eng. & Systems 2024-01-17 Rujing Xiong , Xuihui Dong , Tiebin Mi , Kai Wan , Robert Caiming Qiu

This paper investigates the problem of resource allocation for multiuser communication networks with a reconfigurable intelligent surface (RIS)-assisted wireless transmitter. In this network, the sum transmit power of the network is…

Signal Processing · Electrical Eng. & Systems 2020-09-25 Zhaohui Yang , Wei Xu , Chongwen Huang , Jianfeng Shi , Mohammad Shikh-Bahaei

Reconfigurable intelligent surface (RIS) can be employed in a cell-free system to create favorable propagation conditions from base stations (BSs) to users via configurable elements. However, prior works on RIS-aided cell-free system…

Information Theory · Computer Science 2022-08-15 Xu Gan , Caijun Zhong , Chongwen Huang , Zhaohui Yang , Zhaoyang Zhang

Reconfigurable intelligent surface (RIS) is regarded as a promising technology with great potential to boost wireless networks. Affected by the "double fading" effect, however, conventional passive RIS cannot bring considerable performance…

Signal Processing · Electrical Eng. & Systems 2022-10-06 Qi Zhu , Ming Li , Rang Liu , Yang Liu , Qian Liu

Double-reconfigurable intelligent surface (RIS) is a promising technique, achieving a substantial gain improvement compared to single-RIS techniques. However, in double-RIS-aided systems, accurate channel estimation is more challenging than…

Information Theory · Computer Science 2022-11-30 Songjie Yang , Wanting Lyu , Yue Xiu , Zhongpei Zhang , Chau Yuen

This paper proposes a two-stage approach for passive and active beamforming in multiple-input multiple-output (MIMO) interference channels (ICs) assisted by a beyond-diagonal reconfigurable intelligent surface (BD-RIS). In the first stage,…

Information Theory · Computer Science 2025-03-26 Ignacio Santamaria , Mohammad Soleymani , Eduard Jorswieck , Jesus Gutierrez

In this paper, we consider a hybrid reconfigurable intelligent surface (RIS) comprising of active and passive elements to aid an integrated sensing and communication (ISAC) system serving multiple users and targets. Active elements in a…

Signal Processing · Electrical Eng. & Systems 2022-03-14 R. S. Prasobh Sankar , Sundeep Prabhakar Chepuri