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Article
Engineering, Electrical & Electronic
Zijian Zhang et al.
Summary: This paper proposes the concept of active reconfigurable intelligent surfaces (RISs) to overcome the capacity limitation of passive RISs in strong direct link scenarios. By integrating amplifiers into the elements, active RISs can amplify the reflected signals. The signal model of active RISs is developed and verified through experimental measurements, and the significant capacity gain they provide for wireless communications is analyzed. A joint transmit beamforming and reflect precoding scheme is proposed to maximize the sum-rate in an active RIS aided multi-user multiple-input single-output (MU-MISO) system. Simulation results show that active RISs can achieve a significant sum-rate gain of 130% in comparison to the limited 22% gain of passive RISs, thus overcoming the multiplicative fading effect.
IEEE TRANSACTIONS ON COMMUNICATIONS
(2023)
Article
Engineering, Electrical & Electronic
Asmaa Abdallah et al.
Summary: This paper proposes data-driven and compressive sensing based approaches to estimate both frequency-flat and frequency-selective cascaded channels of RIS-assisted multi-user millimeter-wave large MIMO systems with limited training overhead. The proposed algorithms exploit the common sparsity property among different subcarriers and the double-structured sparsity property of the angular cascaded channel matrices. Simulation results show that the proposed scheme achieves lower pilot overhead and significantly reduces complexity compared to existing schemes.
IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS
(2023)
Article
Engineering, Electrical & Electronic
Aymen Khaleel et al.
Summary: This paper proposes a novel solution that combines RIS with NOMA to improve spectrum efficiency and user fairness. By distributing physical resources to different user clusters, the authors solve a complex optimization problem using three efficient search algorithms. Simulation results show that the proposed system outperforms benchmark systems in multiple performance metrics.
IEEE JOURNAL OF SELECTED TOPICS IN SIGNAL PROCESSING
(2022)
Article
Engineering, Electrical & Electronic
Ruikang Zhong et al.
Summary: This paper investigates a reconfigurable intelligent surface (RIS)-assisted multi-user downlink communication system over fading channels, using both non-orthogonal multiple access (NOMA) and orthogonal multiple access (OMA) schemes. The optimization goal is to maximize the effective throughput of the entire transmission period by jointly optimizing the phase shift of the RIS and the power allocation of the AP for each channel block. Deep learning (DL) and reinforcement learning (RL) approaches are proposed to solve the problem and compare their performance.
IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS
(2022)
Article
Engineering, Electrical & Electronic
Jian Chen et al.
Summary: This study proposes an intelligent reconfigurable surface (IRS) assisted semi-grant-free (SGF) NOMA transmission system, and uses multi-agent deep reinforcement learning to solve the optimization problem for maximizing the long-term data rate of all grant-free users (GFUs).
IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS
(2022)
Article
Engineering, Electrical & Electronic
Chao Zhang et al.
Summary: The article discusses a semi-grant-free (semi-GF) NOMA scheme for enhancing network connectivity and spectral efficiency by enabling grant-based (GB) and GF users to share the same spectrum resources. It proposes a novel dynamic protocol to allocate GF users in NOMA transmissions via transmitting various channel quality thresholds. The dynamic protocol is observed to provide more accurate channel quality thresholds than the open-loop protocol, thereby reducing interference from the GF users to a large extent and enhancing outage performance.
IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS
(2022)
Article
Engineering, Electrical & Electronic
Emre Arslan et al.
Summary: Reconfigurable intelligent surface (RIS) technology is investigated for its application in wireless communication networks. RISs can manipulate impinging waves to control the wireless channel, enabling virtual equalization over-the-air. By eliminating inter-symbol interference (ISI) at the receiver, RISs can convert frequency-selective channels to frequency-flat channels.
IET COMMUNICATIONS
(2022)
Article
Telecommunications
Sultangali Arzykulov et al.
Summary: This paper investigates the deployment of an unmanned aerial vehicle (UAV) as a relay to serve multiple secondary users in a hot-spot region. The proposed solution takes into account user clustering, channel assignment, and resource allocation, considering practical limitations such as hardware impairments and interference temperature constraints. Numerical results show that the proposed solution achieves optimal data rates with significantly less transmission power and computational time compared to numerical benchmarks.
IEEE TRANSACTIONS ON COGNITIVE COMMUNICATIONS AND NETWORKING
(2022)
Article
Telecommunications
Mahmoud Aldababsa et al.
Summary: This letter investigates the BER performance of STAR-RISs in NOMA networks. It derives closed-form BER expressions and conducts asymptotic analyses. The results show that STAR-RIS-NOMA outperforms classical NOMA systems, suggesting it as a promising NOMA 2.0 solution.
IEEE COMMUNICATIONS LETTERS
(2022)
Article
Computer Science, Hardware & Architecture
Yuanwei Liu et al.
Summary: This article focuses on the use of reconfigurable intelligent surfaces (RISs) in multiuser networks with orthogonal multiple access (OMA) or non-orthogonal multiple access (NOMA). The interplay between NOMA and RIS is investigated, and the capacity region of RIS-aided single-antenna NOMA networks is compared with the OMA rate region. The impact of RIS deployment location on different multiple access schemes is also studied, and new joint beamformer designs for RIS-aided multiple-antenna NOMA networks are proposed. Open research problems for RIS-NOMA networks are highlighted.
IEEE WIRELESS COMMUNICATIONS
(2022)
Article
Computer Science, Information Systems
Recep A. Tasci et al.
Summary: Reconfigurable intelligent surface (RIS)-assisted communication is a potential candidate for the next generation (6G) wireless networks. This paper presents a simple RIS hardware architecture with a reflection amplifier to address the path loss issue and analyzes its impact on capacity maximization and bit error probability performance. The proposed amplifying RIS design eliminates the double fading problem and improves communication energy efficiency compared to passive RIS.
Article
Engineering, Electrical & Electronic
Zhong Yang et al.
Summary: The study proposes a novel RIS-aided NOMA downlink transmission framework that maximizes the total data rate of mobile users through joint optimization of NOMA user partitioning and RIS phase shifting. Using a modified MOMA algorithm for user clustering and the DDPG algorithm for optimizing RIS phase shifting matrix, the performance of the NOMA framework is enhanced.
IEEE TRANSACTIONS ON COMMUNICATIONS
(2021)
Article
Engineering, Electrical & Electronic
Muhammad Fayaz et al.
Summary: The proposed GF-NOMA algorithm utilizes a multi-agent deep Q-network (DQN) and double DQN (DDQN) to determine optimal transmit power levels for a prototype power pool (PP) based on communication distances. The DDQN algorithm helps prevent overestimation issues and converges faster under changing environmental conditions, outperforming traditional methods.
IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS
(2021)
Article
Telecommunications
Mohamed Elhattab et al.
Summary: The amalgamation of RIS technology and JT-CoMP is investigated to enhance the performance of cell-edge UE without deteriorating NOMA cell-center UE. The proposed framework is validated through closed-form expression for cell-edge UE's ergodic rate and evaluation of network spectral efficiency, showing efficacy compared to other multiple access techniques.
IEEE COMMUNICATIONS LETTERS
(2021)
Article
Computer Science, Information Systems
Jiaqi Liu et al.
Summary: In this study, the grant-free nonorthogonal multiple access (GF-NOMA) method is proposed for IoT applications in the mMTC scenario, enabling efficient data transmission and accurate multiuser detection by allowing devices to transmit preambles and data symbols directly within one time frame. Compressive sensing (CS)-based receivers are used for nonorthogonal preambles (NOPs)-based MUD, with successive interference cancellation decoding superimposed data signals. The system is modeled, analyzed, and optimized using stochastic geometry (SG), with numerical methods used to optimize energy efficiency and AP coverage efficiency for GF-NOMA in order to meet the demands of low-energy consumption and low infrastructure costs for IoT applications.
IEEE INTERNET OF THINGS JOURNAL
(2021)
Article
Engineering, Electrical & Electronic
Xiao Liu et al.
Summary: A novel framework is proposed for the deployment and passive beamforming design of a reconfigurable intelligent surface (RIS) with the aid of non-orthogonal multiple access (NOMA) technology. Machine learning approaches are utilized to tackle the joint problem of deployment and design of RIS, with promising simulation results.
IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS
(2021)
Article
Engineering, Electrical & Electronic
Gang Yang et al.
Summary: Reconfigurable intelligent surface (RIS) is a revolutionary technology for efficient wireless networks, and the paper proposes algorithms to optimize rate performance in an RIS-assisted NOMA system by jointly optimizing transmit beamforming and RIS phase shifts, with efficient algorithms leveraging coordinated descent and SDR techniques. Simulation results show significant rate performance improvement compared to traditional NOMA systems.
IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS
(2021)
Article
Computer Science, Information Systems
Zhiqing Tang et al.
Summary: This letter proposes a novel design of RIS to enhance physical layer security in the RIS-aided NOMA network. The design solves the issue of increasing RIS elements damaging secrecy performance, and allows networks to use traditional channel coding schemes for achieving secrecy. Results indicate that the novel RIS design is effective in enhancing secrecy performance.
IEEE WIRELESS COMMUNICATIONS LETTERS
(2021)
Article
Engineering, Electrical & Electronic
Cunhua Pan et al.
Summary: Reconfigurable intelligent surfaces (RISs) or intelligent reflecting surfaces (IRSs) are considered as one of the most promising and revolutionizing techniques for enhancing the spectrum and energy efficiency of wireless systems by reconfiguring the wireless propagation environment through carefully tuning the phase shifts of a large number of low-cost passive reflecting elements. The article aims to address four fundamental questions and highlights eight promising research directions.
IEEE COMMUNICATIONS MAGAZINE
(2021)
Article
Engineering, Electrical & Electronic
Ruizhe Long et al.
Summary: The paper introduces a new type of RIS, called active RIS, which enhances the incoming signal by incorporating active loads to each reflecting element, in contrast to conventional passive RIS systems. However, this amplification may unintentionally boost RIS-correlated noise, requiring optimization of the reflecting coefficient matrix at the RIS and receive beamforming at the receiver to strike a balance between maximizing received signal power and minimizing RIS-related noise.
IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS
(2021)
Article
Engineering, Electrical & Electronic
Zhe Zhang et al.
Summary: This paper investigates the physical layer security (PLS) for a RIS-aided NOMA 6G networks, where a RIS is deployed to assist two dead zone NOMA users and internal/external eavesdropping are considered. The proposed joint beamforming and power allocation scheme aims to improve system PLS, with superior performance shown in simulation results. Increasing the number of reflecting elements is found to bring more gain in secrecy performance than increasing the number of transmit antennas.
IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY
(2021)
Article
Engineering, Electrical & Electronic
Sultangali Arzykulov et al.
Summary: The paper investigates the performance of a cooperative CR-NOMA network in the presence of system impairments and interference, proposing an optimal power allocation scheme for users. Results show that the CR-NOMA network outperforms orthogonal multiple access in outage performance. However, increasing system imperfections lead to degradation in performance for CR-NOMA networks.
IEEE OPEN JOURNAL OF THE COMMUNICATIONS SOCIETY
(2021)
Article
Computer Science, Information Systems
Qin Chen et al.
Summary: NOMA technology combined with reconfigurable Intelligent surfaces (RIS) and IoT is proposed in this study. The impact of residual hardware impairment (RHI) on physical layer security (PLS) performance is investigated, with derived expressions of user's secrecy outage probability (SOP). Simulation results show improved system performance relying on NOMA with RIS compared to OMA and conventional NOMA.
Article
Engineering, Electrical & Electronic
Ibrahim Yildirim et al.
Summary: This paper investigates the potential benefits of using RIS in indoor/outdoor setups and various frequency bands, with a focus on the effect of reflecting elements on signal-to-noise ratio, error performance, path loss exponent, and transmission models with multiple RISs. Through extensive simulations, it is demonstrated that RIS-assisted systems provide promising solutions for indoor/outdoor scenarios at various operating frequencies, even in the presence of system imperfections.
IEEE TRANSACTIONS ON COMMUNICATIONS
(2021)
Article
Computer Science, Information Systems
Atluri Hemanth et al.
Article
Computer Science, Information Systems
Emre Arslan et al.
IEEE WIRELESS COMMUNICATIONS LETTERS
(2020)
Article
Engineering, Electrical & Electronic
Tianwei Hou et al.
IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS
(2020)
Article
Computer Science, Information Systems
Muhammad Basit Shahab et al.
IEEE COMMUNICATIONS SURVEYS AND TUTORIALS
(2020)
Article
Engineering, Electrical & Electronic
Marco Di Renzo et al.
IEEE OPEN JOURNAL OF THE COMMUNICATIONS SOCIETY
(2020)
Article
Engineering, Electrical & Electronic
Rana Abbas et al.
IEEE TRANSACTIONS ON COMMUNICATIONS
(2019)
Article
Engineering, Electrical & Electronic
Seda Dogan et al.
IEEE JOURNAL OF SELECTED TOPICS IN SIGNAL PROCESSING
(2019)
Article
Engineering, Electrical & Electronic
Qingqing Wu et al.
IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS
(2019)
Article
Computer Science, Information Systems
Ertugrul Basar et al.
Article
Computer Science, Information Systems
S. M. Riazul Islam et al.
IEEE COMMUNICATIONS SURVEYS AND TUTORIALS
(2017)
Article
Engineering, Electrical & Electronic
Behrooz Makki et al.
IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS
(2015)
Article
Telecommunications
Daniel Persson et al.
IEEE COMMUNICATIONS LETTERS
(2013)
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Engineering, Electrical & Electronic
Krishna Kumar Kishor et al.
IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION
(2012)