Literatura académica sobre el tema "Surfaces intelligentes reconfigurables (RIS)"
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Artículos de revistas sobre el tema "Surfaces intelligentes reconfigurables (RIS)"
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Wang, Wenhe y Kang Song. "Hybrid Active–Passive Reconfigurable Intelligent Surface for Cooperative Transmission Systems". Applied Sciences 14, n.º 1 (27 de diciembre de 2023): 231. http://dx.doi.org/10.3390/app14010231.
Texto completoResumen
Reconfigurable intelligent surfaces (RISs) are acknowledged as one of the key technologies for the next-generation communications systems due to their low cost, high-energy efficiency, and the ability to intelligently control the wireless propagation environment. In this paper, we present a hybrid active–passive reconfigurable intelligent surface (HAPR) for cooperative transmission system, where HAPR can intelligently change its operating mode according to the channel environment, eliminating the “multiplicative fading” effect of traditional passive RIS (P-RIS) and higher power consumption of active RIS (A-RIS), and combining the advantages of both to effectively improve the system performance. First, we investigate the ideal reflection coefficient of RIS reflecting elements (REs) under the condition of a limited power budget. Using the compound Simpson formula, the closed-form approximation expression for the system outage probability (OP) has been derived. Finally, Monte Carlo simulation is used to confirm the accuracy of the expression. The simulation results demonstrate that HAPR has a better performance than both A-RIS and P-RIS, which can achieve a lower OP.
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Widodo, Agung Mulyo, Heri Wijayanto, I. Gede Pasek Suta Wijaya, Andika Wisnujati y Ahmad Musnansyah. "Analyzing Coverage Probability of Reconfigurable Intelligence Surface-aided NOMA". JOIV : International Journal on Informatics Visualization 7, n.º 3 (10 de septiembre de 2023): 839. http://dx.doi.org/10.30630/joiv.7.3.2054.
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Along with the explosive growth of wireless communication network users who require large frequency bands and low latency, it is a challenge to create a new wireless communication network beyond 5G. This is because installing a massive 5G network requires a large investment by network providers. For this reason, the authors propose an alternative beyond 5G that has better quality than 5G and a relatively lower investment value than 5G networks. This study aims to analyze the downlink of the cooperative non-orthogonal multiple access (NOMA) network, which is usually used in 5G, combined with the use of a reconfigurable intelligence surface (RIS) antenna with decode and forward relay mechanisms. RIS is processed with a limited number of objects utilizing Rayleigh fading channels. The scenario is created by a user who relays without a direct link for users near the base station and with a direct link for users far from the base station. Under the Nakagami-m fading channel, the authors carefully evaluated the probability of loss for various users as a function of perfect channel statistical information (p-CSI) utilizing simply a single input-output (SISO) system with a finite number of RIS elements. As a key success metric, the efficiency of the proposed RIS-assisted NOMA transmission mechanism is evaluated through numerical data on the outage probability for each user. The modeling outcomes demonstrate that the RIS-aided NOMA network outperforms the traditional NOMA network
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Rana, Biswarup, Sung-Sil Cho y Ic-Pyo Hong. "Passive Type Reconfigurable Intelligent Surface: Measurement of Radiation Patterns". Micromachines 14, n.º 4 (5 de abril de 2023): 818. http://dx.doi.org/10.3390/mi14040818.
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The demand for unprecedented data and ubiquitous wireless connections have led to the adoption of new types of transmitters and receivers. Additionally, different new types of devices and technologies need to be proposed for such demand. Reconfigurable intelligent surface (RIS) is going to play a very significant role in the upcoming beyond-5G/6G communications. It is envisioned that not only the RIS will be deployed to assist and create a smart wireless environment for the upcoming communications, but also the receiver and transmitter can be fabricated using RIS to make a smart and intelligent transmitter and receiver. Thus, the latency of upcoming communications can be reduced very significantly using RIS, which is a very important factor. Artificial intelligence assists communications and shall be adopted widely for the next generation networks. In this paper, radiation pattern measurement results of our previously published RIS have been provided. This work is the extension work of our previously proposed RIS. The polarization-independent passive type of RIS working in the sub-6 GHz frequency band using low-cost FR4-substrate was designed. Each unit cell with dimensions of 42 mm × 42 mm had a single-layer substrate backed by a copper plate. A 10 × 10-unit cell array was fabricated to check the performance of the RIS. Such types of unit cells and RIS were designed to set up initial measurement facilities in our laboratory for any kinds of RIS measurements.
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Yu Lu, Hao Jiang y Linglong Dai. "Artificial intelligence for RIS-aided wireless communications". ITU Journal on Future and Evolving Technologies 4, n.º 1 (6 de marzo de 2023): 70–77. http://dx.doi.org/10.52953/hymy1464.
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The recently proposed Reconfigurable Intelligent Surface (RIS) can reconstruct the wireless channels between the transceivers, thus it is regarded as a promising technology for future 6G wireless networks to enlarge their coverage and improve the capacity. However, RISs also impose some new challenges, such as an unaffordable overhead for channel estimation and high complexity for real-time beam-forming. Fortunately, the impressive success of Artificial Intelligence (AI) in various fields has inspired its application in RIS-aided communications to address these challenges. In this paper, two pairs of dominant methodologies of using AI for RIS-aided wireless communications are discussed. The first one is the AI-based algorithm design, which is illustrated by some examples of typical transmission techniques. The second one is the AI-based architecture design, which breaks the classical block-based design rule of wireless communications in the past few decades. The interplay between AI and RIS is also highlighted. Finally, key challenges and future opportunities in this emerging area are pointed out. We expect that this paper will stimulate more promising AI-based investigations for RIS-aided wireless communications.
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Goh, Chi Yen, Chee Yen Leow y Rosdiadee Nordin. "Energy Efficiency of Unmanned Aerial Vehicle with Reconfigurable Intelligent Surfaces: A Comparative Study". Drones 7, n.º 2 (31 de enero de 2023): 98. http://dx.doi.org/10.3390/drones7020098.
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Unmanned aerial vehicles (UAVs) and reconfigurable intelligent surfaces (RIS) are the promising emerging technologies proposed for the 6th-Generation (6G) network to improve the capacity, reliability, and coverage of wireless communications. By integrating the UAV with RIS (RIS-UAV), the three-dimensional (3D) mobility of the UAV can be leveraged to establish strong line-of-sight links with the ground nodes, while the RIS intelligently reflect the signals toward the desired directions. However, the existing literature on RIS-UAV systems mainly assumes the use of passive elements, which suffers from the double path-loss problem. The use of active elements in RIS, which could improve the reflected link performance at the cost of increased energy consumption, has not been considered for the RIS-UAV system. Further, the energy efficiency of a RIS-UAV with active elements remains as an open direction because there is a need to investigate the feasibility of either an active or hybrid RIS-UAV implementation. This paper proposes active and hybrid RIS-UAVs and investigates the energy efficiencies of active and hybrid RIS-UAVs in comparison with existing passive RIS-UAVs and conventional UAV relays. The numerical results reveal that the proposed hybrid and active RIS-UAV relaying schemes can provide up to 14 times and 26 times improvement as compared to the passive RIS-UAV, respectively. As opposed to the active RIS-UAV that requires a larger power budget, half-duplex UAV relays that have a lower spectral efficiency, and full-duplex UAV relays that suffer from self-interference, the hybrid RIS-UAV emerges as a promising option to assist the ground communication system.
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Martín-Martín, Alberto, Rubén Padial-Allué, Encarnación Castillo, Luis Parrilla, Ignacio Parellada-Serrano, Alejandro Morán y Antonio García. "Hardware Implementations of a Deep Learning Approach to Optimal Configuration of Reconfigurable Intelligence Surfaces". Sensors 24, n.º 3 (30 de enero de 2024): 899. http://dx.doi.org/10.3390/s24030899.
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Reconfigurable intelligent surfaces (RIS) offer the potential to customize the radio propagation environment for wireless networks, and will be a key element for 6G communications. However, due to the unique constraints in these systems, the optimization problems associated to RIS configuration are challenging to solve. This paper illustrates a new approach to the RIS configuration problem, based on the use of artificial intelligence (AI) and deep learning (DL) algorithms. Concretely, a custom convolutional neural network (CNN) intended for edge computing is presented, and implementations on different representative edge devices are compared, including the use of commercial AI-oriented devices and a field-programmable gate array (FPGA) platform. This FPGA option provides the best performance, with ×20 performance increase over the closest FP32, GPU-accelerated option, and almost ×3 performance advantage when compared with the INT8-quantized, TPU-accelerated implementation. More noticeably, this is achieved even when high-level synthesis (HLS) tools are used and no custom accelerators are developed. At the same time, the inherent reconfigurability of FPGAs opens a new field for their use as enabler hardware in RIS applications.
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Hong, Ic-Pyo. "Reviews Based on the Reconfigurable Intelligent Surface Technical Issues". Electronics 12, n.º 21 (1 de noviembre de 2023): 4489. http://dx.doi.org/10.3390/electronics12214489.
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Reconfigurable intelligent surfaces (RISs) are programmable metasurface structures that can control the propagation of electromagnetic waves by changing the electrical and magnetic properties of the surface. They can be used to intelligently reconfigure the wireless environment to improve the capacity and coverage of wireless networks. In recent years, numerous theoretical innovations and prototype tests have demonstrated that the RIS has the advantages of low cost, low power consumption, and easy deployment, and creates many potential opportunities and broad application prospects in 5G and future 6G networks. In this paper, starting from the technological development of RISs, we discussed the technical issues of RISs. The standardization of RISs, types of RISs according to operation modes, channel modeling, considerations for hardware implementation, differences from existing communication modules and the need for active RIS implementation, noise and power characteristics to ensure the efficiency of RISs, and performance parameters of RISs and field test results of RISs in indoor and outdoor environments were reviewed. By resolving the current technical issues of RISs, it is expected that RISs will be successfully used for B5G/6G communication through commercialization.
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Wang, Yi, Haibo Wang y XueWen Jiang. "Performance of Reconfigurable-Intelligent-Surface-Assisted Satellite Quasi-Stationary Aircraft–Terrestrial Laser Communication System". Drones 6, n.º 12 (8 de diciembre de 2022): 405. http://dx.doi.org/10.3390/drones6120405.
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This paper proposes the use of quasi-stationary aircraft and reconfigurable intelligent surfaces (RIS) to improve the system performance in satellite–terrestrial laser communication downlink. Single-input multiple-output (SIMO) technology is applied to the relay node of a quasi-stationary aircraft. The closed expression of the bit error rate (BER) of an RIS-assisted satellite quasi-stationary aircraft–terrestrial laser communication system (RIS-SHTLC) is derived under the M-distributed atmospheric turbulence model while considering the influence of atmospheric turbulence and pointing errors caused by RIS jitter. The effects of coherent binary frequency shift keying (CBFSK), coherent binary phase-shift keying (CBPSK), non-coherent binary frequency shift keying (NBFSK), and differential binary phase-shift keying (DBPSK) on the performance of an RIS-SHTLC system are simulated and analyzed under weak turbulence. The results show that the RIS-SHTLC system with CBPSK modulation has the best communication performance. Simultaneously, the relationships between the average signal-to-noise ratio (SNR) and BER of the RIS-SHTLC system under different RIS elements are simulated and analyzed, and compared with the traditional SHTLC system. In addition, the influence of the zenith angle, receiving aperture and divergence angle on the performance of the system is studied. Finally, Monte Carlo simulations are used to validate the analytical results.
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Li, Zongze, Shuai Wang, Qingfeng Lin, Yang Li, Miaowen Wen, Yik-Chung Wu y H. Vincent Poor. "Phase Shift Design in RIS Empowered Wireless Networks: From Optimization to AI-Based Methods". Network 2, n.º 3 (11 de julio de 2022): 398–418. http://dx.doi.org/10.3390/network2030025.
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Reconfigurable intelligent surfaces (RISs) offer the potential to customize the radio propagation environment for wireless networks. To fully exploit the advantages of RISs in wireless systems, the phases of the reflecting elements must be jointly designed with conventional communication resources, such as beamformers, the transmit power, and computation time. However, due to the unique constraints on the phase shifts and the massive numbers of reflecting units and users in large-scale networks, the resulting optimization problems are challenging to solve. This paper provides a review of the current optimization methods and artificial-intelligence-based methods for handling the constraints imposed by RISs and compares them in terms of the solution quality and computational complexity. Future challenges in phase-shift optimization involving RISs are also described, and potential solutions are discussed.
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Shi, Baihua, Yang Wang, Danqi Li, Wenlong Cai, Jinyong Lin, Shuo Zhang, Weiping Shi, Shihao Yan y Feng Shu. "STAR-RIS-UAV-Aided Coordinated Multipoint Cellular System for Multi-User Networks". Drones 7, n.º 6 (17 de junio de 2023): 403. http://dx.doi.org/10.3390/drones7060403.
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Different from conventional reconfigurable intelligent surfaces (RIS), simultaneous transmitting and reflecting RIS (STAR-RIS) can reflect and transmit signals to the receiver. In this paper, to serve more ground users and increase deployment flexibility, we investigate an unmanned aerial vehicle (UAV) equipped with STAR-RIS (STAR-RIS-UAV)-aided wireless communications for multi-user networks. Energy splitting (ES) and mode switching (MS) protocols are considered to control the reflection and transmission coefficients of STAR-RIS elements. To maximize the sum rate of the STAR-RIS-UAV-aided coordinated multipoint (CoMP) cellular system for multi-user networks, the corresponding beamforming vectors as well as transmitted and reflected coefficient matrices are optimized. Specifically, instead of adopting the alternating optimization, we design an iteration method to optimize all variables for both the ES and MS protocols at the same time. Simulation results reveal that the STAR-RIS-UAV-aided CoMP system has a much higher sum rate than systems with conventional RIS or without RIS. Furthermore, the proposed structure is more flexible than fixed STAR-RIS and could greatly promote the sum rate.
Tesis sobre el tema "Surfaces intelligentes reconfigurables (RIS)"
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Mohamed, Abdelhamed. "Optimization Techniques for Reconfigurable Intelligent Surfaces Assisted Wireless Networks". Electronic Thesis or Diss., université Paris-Saclay, 2022. http://www.theses.fr/2022UPAST137.
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Récemment, l'émergence des surfaces intelligentes reconfigurables (RIS) a suscité une vive attention de l'industrie et du monde universitaire. Un RIS est une surface plane constituée d'un grand nombre d'éléments réfléchissants passifs à faible coût. En ajustant soigneusement les déphasages des éléments réfléchissants, un RIS peut remodeler l'environnement sans fil pour une meilleure communication. En général, cette thèse fournit des contributions sur : (i) les performances des RIS basées sur des modèles de rayonnement électromagnétique précis et réalistes. De plus, elle fournit des cadres d'optimisation pour améliorer la performance des systèmes de communication dans les deux cas d'utilisation suivants : (i) Améliorer conjointement le taux d'information et la quantité de puissance récoltée dans un réseau sans fil multi-utilisateurs MISO descendant assisté par les RIS. (ii) améliorer l'efficacité spectrale pour un grand nombre d'utilisateurs situés en bordure de cellule ou de l'autre côté du RIS en utilisant des omni-surfaces intelligentes (IOS). Le chapitre 1 présente les défis à relever pour répondre aux exigences des réseaux 6G, le concept d'environnements radio intelligents et les RIS, qui constituent l'une des technologies habilitantes. Dans les communications futures, les RIS sont une technique clé qui aura des applications potentielles permettant d'obtenir une connectivité sans faille tout en consommant moins d'énergie. Le chapitre 2 présente les systèmes de communication assistés par RIS. Le principe de réflexion, le problème d'estimation de canal et le problème de conception du système sont présentés en détail. Les recherches de pointe sur les problèmes d'estimation de canal et de conception de système sont passées en revue. Le chapitre 3 étudie l'impact de modèles de reradiation réalistes pour les RIS en fonction de l'inter-distance sub-longueur d'onde entre les éléments proches du RIS, les niveaux de quantification des coefficients de réflexion, l'interaction entre l'amplitude et la phase des coefficients de réflexion, et la présence d'interférences électromagnétiques. En conclusion, notre étude montre que, en raison de contraintes de conception, telles que la nécessité d'utiliser des coefficients de réflexion quantifiés ou l'interaction inhérente entre la phase et l'amplitude des coefficients de réflexion, un RIS peut reradir la puissance vers des directions non désirées qui dépendent des ondes électromagnétiques prévues et interférentes. Le chapitre 4 aborde le problème de l'optimisation simultanée du taux d'information et de la puissance récoltée dans un réseau sans fil multi-utilisateurs MISO en liaison descendante avec surface intelligente reconfigurable (RIS) et transfert simultané d'information et de puissance sans fil (SWIPT). Un algorithme pratique est développé par une interaction entre l'optimisation alternée, l'optimisation séquentielle et les méthodes basées sur les prix. Le chapitre 5 propose un algorithme d'optimisation qui a un taux de convergence rapide en quelques itérations pour maximiser le taux de somme dans les canaux de diffusion MIMO assistés par IOS, qui peut être exploité pour servir l'utilisateur de bord de cellule et améliorer la couverture du réseau. La particularité de ce travail est de considérer que les coefficients de réflexion et de transmission d'un IOS sont étroitement couplés. Enfin, le chapitre 6 résume les principales conclusions de la thèse et discute des orientations futures possibles qui méritent d'être étudiées pour libérer tout le potentiel des RIS et les mettre en pratiqueRecently, the emergence of reconfigurable intelligent surface (RIS) has attracted heated attention from both industry and academia. An RIS is a planar surface that consists of a large number of low-cost passive reflecting elements. By carefully adjusting the phase shifts of the reflecting elements, an RIS can reshape the wireless environment for better communication. In general, this thesis provides contributions on: (i) the performance of RISs based on accurate and realistic electromagnetic reradiation models. Moreover, it provides some of optimization frameworks for enhancing the communication system performance on the following two use case: (i) To jointly improves the information rate and the amount of harvested power in a RIS-aided MISO downlink multiuser wireless network. (ii) enhancing spectral efficiency for large number of users located on cell edge or on the other side of the RIS by utilizing the intelligent omni-surfaces (IOSs).Chapter 1 introduces the challenges of fulfilling the requirements of of 6G networks, the concept of smart radio environments and RIS as it is one of the enabling technologies. In future communications, RIS is a key technique that will have potential applications which will achieve seamless connectivity and less energy consumption at the same time. Chapter 2 also introduces the state-of-art optimization techniques developed for RIS-aided systems. Firstly, it introduces the system models of RIS-aided MIMO systems and then investigates the reflection principle of RISs. In addition, it introduces the Optimization techniques challenges of RIS-assisted systems. Also, the proposed optimization techniques for designing the continuous and discrete phase shifts are presented in detail. Chapter 3 studies the impact of realistic reradiation models for RISs as a function of the sub-wavelength inter-distance between nearby elements of the RIS, the quantization levels of the reflection coefficients, the interplay between the amplitude and phase of the reflection coefficients, and the presence of electromagnetic interference. In conclusion, our study shows that, due to design constraints, such as the need to use quantized reflection coefficients or the inherent interplay between the phase and the amplitude of the reflection coefficients, a RIS may reradiate power towards unwanted directions that depend on the intended and interfering electromagnetic waves. Chapter 4 considers the problem of simultaneously optimizing the information rate and the harvested power in a reconfigurable intelligent surface (RIS)-aided MISO downlink multiuser wireless network with simultaneous wireless information, and power transfer (SWIPT) is addressed. A practical algorithm is developed through an interplay of alternating optimization, sequential optimization, and pricing-based methods. Chapter 5 proposes an optimization algorithm that has a rapid convergence rate in a few iterations for maximizing the sum rate in IOS-aided MIMO broadcast channels, which can be exploited to serve the cell-edge user and enhance network coverage. This work's distinguishable feature lies in considering that the reflection and transmission coefficients of an IOS are tightly coupled. Finally, Chapter 6 summarizes the main findings of the thesis and discusses possible future directions that are worth investigating to unlock the full potential of RIS and bring it into practice
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Liu, Yicong. "A Dynamic Subarray Structure in Reconfigurable Intelligent Surfaces for TeraHertz Communication Systems". Thesis, The University of Sydney, 2022. https://hdl.handle.net/2123/29611.
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Reconfigurable Intelligent Surfaces (RIS) have recently gained popularity as a TeraHertz (THz) multi-input multi-output (MIMO) communication solution. THz range (0.1-10 THz) is critical for ubiquitous wireless communications. THz frequencies, in particular, promise to provide sufficient spectrum, data rates exceeding a hundred gigabits per second (Gbps), huge interconnectedness, denser networks, and highly secure communications. While a higher carrier frequency entails a larger communication path loss. To lower it, the primary option is to improve the reflecting signal, and RIS has several benefits that make it a good candidate for THz communication.
When the size of a Base Station (BS) antenna is constant, a larger RIS array can boost spectral efficiency, according to earlier studies. However, if the RIS is significantly larger than the BS, the BS beam will not cover the entire RIS array. So there is a trade-off between the spectral efficiency and the number of RIS elements where RIS utilization is maximal.
Different from finding out the appropriate amount of RIS elements in a system, optimizing the RIS reflecting pattern to improve the coverage of BS beams and raise the system spectral efficiency is another technical route. Based on that, on the one hand, we separate the whole RIS array into some of subarrays, and each subarray aligns to only one corresponding user, making RIS-subarray-user pairs in a multiuser THz communication system. On the other hand, a system with a general RIS structure where the RIS reflects beams to all users without subarray is considered as a comparison.
Each RIS subarray independently reflects the beam to the corresponding user in this system. We settle it because if the size of RIS is much larger than the BS array, the beams from BS to RIS will hardly cover all RIS elements, and the utilization rate of RIS will be lower down.
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Giorgini, Giacomo. "Channel estimation schemes in the presence of reconfigurable intelligent surfaces". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021. http://amslaurea.unibo.it/22878/.
Texto completoResumen
Il progetto di tesi svolto riguarda lo studio di alcuni schemi di stima del canale di propagazione in presenza di superfici intelligenti riconfigurabili (comunemente chiamate RIS).
Nel Capitolo 1 viene mostrato il vantaggio di adottare una RIS, mentre nel Capitolo 2 quest'ultima viene analizzata più nel dettaglio, introducendo anche il problema di stima del canale in scenari simili.
Nel Capitolo 3 viene presentato lo stato dell'arte relativo ai principali approcci di stima del canale studiati in letteratura e viene analizzato nel dettaglio uno dei principali approcci ottimi validi nel caso di sistemi singola antenna, in cui la comunicazione viene assistita da una singola RIS, ed un secondo approccio valido nel caso di sistemi multi-antenna.
Essendo il numero elevato di toni pilota necessari per la stima del CSI negli algoritmi presenti in letteratura il principale problema da affrontare, nel Capitolo 4 viene proposto un nuovo algoritmo, valido nel caso SISO, in grado di superare questo grosso limite. In particolare, viene analizzato il profilo di fase del canale sia in condizioni di campo lontano che campo vicino, e viene poi illustrato nel dettaglio come tali informazioni possono essere sfruttare per stimare il canale tramite un approccio ML. Le simulazioni che seguono, fanno vedere come un simile approccio sia in grado di ottenere delle valide stime delle informazioni di canale sfruttando solamente il 10/15$\%$ dei toni pilota necessari nell'approccio ottimo descritto nel Capitolo 3. Viene poi evidenziato come il problema di stima del canale sia equivalente al problema di stima della posizione del ricevitore. In particolare, note le posizioni del trasmettitore e della RIS adottata, viene illustrato un metodo (strettamente collegato all'approccio di stima del canale) di stima della posizione del ricevitore.
Infine, nel Capitolo 5, vengono presentate le conclusioni e possibili sviluppi futuri correlati all'algoritmo proposto nel capitolo precedente.
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Liu, Jiang. "Wireless Communications Assisted by Reconfigurable Intelligent Surfaces". Electronic Thesis or Diss., université Paris-Saclay, 2021. http://www.theses.fr/2021UPASG111.
Texto completoResumen
Récemment, l'émergence de la surface intelligente reconfigurable (RIS) a attiré l'attention de l'industrie et du monde universitaire. Un RIS est une surface plane qui se compose d'un grand nombre d'éléments réfléchissants passifs à faible coût. En ajustant soigneusement les déphasages des éléments réfléchissants, un RIS peut remodeler l'environnement sans fil pour une meilleure communication. Dans cette thèse, nous nous concentrons sur deux sujets : (i) Étudier la modélisation et l'optimisation des systèmes de communication assistés par RIS. (ii) Étudier la modulation spatiale assistée par RIS, en particulier la détection à l'aide de techniques d'apprentissage en profondeur. Le chapitre 1 présente le concept d'environnements radio intelligents et de SIF. Dans la 5G et les communications futures, le RIS est une technique clé pour obtenir une connectivité transparente et une consommation d'énergie moindre en même temps. Le chapitre 2 présente les systèmes de communication assistés par RIS. Le principe de réflexion, le problème d'estimation de canal et le problème de conception du système sont présentés en détail. Les recherches de pointe sur les problèmes d'estimation de canal et de conception de système sont passées en revue. Le chapitre 3 étudie la distribution du rapport signal sur bruit (SNR) en tant que variable aléatoire dans un système MIMO (entrées multiples et sorties multiples) assisté par RIS. L'évanouissement de Rayleigh et la propagation en visibilité directe sont considérés séparément. La dérivation théorique et la simulation numérique prouvent que le SNR est équivalent en distribution au produit de trois (évanouissement de Rayleigh) ou de deux (propagation en ligne de visée) variables aléatoires indépendantes. Le chapitre 4 étudie le comportement des interférences dans un système MIMO assisté par RIS, où chaque station de base dessert un équipement utilisateur (UE) via un RIS. L'interférence au niveau d'un UE est causée par son RIS non desservant. Il est prouvé que le rapport interférence/bruit est équivalent en distribution au produit d'une variable aléatoire Chi-carré et d'une variable aléatoire qui peut être approchée avec une distribution Gamma. Le chapitre 5 se concentre sur la modulation spatiale assistée par RIS. Tout d'abord, nous introduisons la détection assistée par apprentissage en profondeur pour les systèmes MIMO. Ensuite, en généralisant les systèmes de modulation spatiale assistés par RIS en tant que cas particulier des systèmes de modulation spatiale traditionnels, nous étudions la détection basée sur l'apprentissage en profondeur pour les systèmes de modulation spatiale assistés par RIS. Les résultats numériques valident les schémas de détection d'apprentissage en profondeur basés sur des données et sur des modèles pour les systèmes de modulation spatiale assistés par RIS. Enfin, le chapitre 6 conclut la thèse et discute des pistes de recherche futures possiblesRecently, the emergence of reconfigurable intelligent surface (RIS) has attracted heated attention from both industry and academia. A RIS is a planar surface that consists of a large number of low-cost passive reflecting elements. By carefully adjusting the phase shifts of the reflecting elements, an RIS can reshape the wireless environment for better communication. In this thesis, we focus on two subjects: (i) To study the modeling and optimization of RIS-aided communication systems. (ii) To study RIS-aided spatial modulation, especially the detection using deep learning techniques. Chapter 1 introduces the concept of smart radio environments and RIS. In 5G and future communications, RIS is a key technique to achieve seamless connectivity and less energy consumption at the same time. Chapter 2 introduces RIS-aided communication systems. The reflection principle, channel estimation problem and system design problem are introduced in detail. State-of-the-art research on the problems of channel estimation and system design are overviewed. Chapter 3 investigates the distribution of the signal-to-noise ratio (SNR) as a random variable in an RIS-aided multiple-input multiple-output (MIMO) system. Rayleigh fading and line-of-sight propagation are considered separately. The theoretical derivation and numerical simulation prove that the SNR is equivalent in distribution to the product of three (Rayleigh fading) or two (line-of-sight propagation) independent random variables. Chapter 4 studies the behavior of interference in an RIS-aided MIMO system, where each base station serves a user equipment (UE) through an RIS. The interference at a UE is caused by its non-serving RIS. It is proven that the interference-to-noise ratio is equivalent in distribution to the product of a Chi-squared random variable and a random variable which can be approximated with a Gamma distribution. Chapter 5 focuses on RIS-aided spatial modulation. First, we introduce deep learning aided detection for MIMO systems. Then, by generalizing RIS-aided spatial modulation systems as a special case of traditional spatial modulation systems, we investigate deep learning based detection for RIS-aided spatial modulation systems. Numerical results validate the proposed data-based and model-based deep learning detection schemes for RIS-aided spatial modulation systems. Finally, Chapter 6 concludes the thesis and discusses possible future research directions
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Danufane, Fadil. "Wireless communications assisted by reconfigurable intelligent surfaces : an electromagnetic model". Electronic Thesis or Diss., université Paris-Saclay, 2021. http://www.theses.fr/2021UPASG038.
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L'émergence de l'environnement radio intelligent (SRE) en tant que nouveau paradigme qui remet en question le status quo dans la communication sans fil a motivé l'utilisation des surface intelligentes reconfigurables (RIS) basées sur des métasurfaces pour améliorer la limite de performance des systèmes de communication sans fil. L'objectif principal de cette thèse est la modélisation d'un système de communication assisté par un RIS à l'aide d'approches basées sur l'électromagnétisme.Le Chapitre 1 présente le concept d'environnement radio intelligent. Nous donnons également la définition du RIS et comment le RIS peut être utilisé dans le contexte du SRE. Nous donnons aussi quelques perspectives historiques et discutons le développement des activités de recherche dans ce contexte.Le Chapitre 2 présente les concepts théoriques nécessaires pour comprendre les résultats des chapitres suivants. Ce chapitre est divisé en deux parties. La première partie traite de la modélisation des métasurfaces où nous passons d'une description microscopique basée sur la physique d'une métasurface et introduisons une représentation macroscopique de celle-ci, qui s'avère appropriée pour une application aux communications sans fil. La deuxième partie présente plusieurs approches analytiques qui nous permettent de calculer le champ électromagnétique dans un certain volume..Le Chapitre 3 fournit une comparaison des performances entre les RISs fonctionnant comme des réflecteurs anormaux et un schéma de relais basé sur le décodage et la transmission. La comparaison est qualitative et couvre une multitude de métriques. En outre, une comparaison quantitative en termes de débits de données réalisables est également présentée. En particulier, les résultats numériques montrent que des RISs suffisamment grands peuvent être plus performants que les systèmes assistés par relais en termes de débit de données, tout en réduisant la complexité.Le Chapitre 4 propose une caractérisation analytique du champ électromagnétique en présence d'un RIS qui est modélisé comme une métasurface homogénéisée et qui fonctionne soit en réflexion ou transmission. Des expressions de forme fermée sont également obtenues dans deux régimes asymptotiques qui sont représentatifs de deux déploiements en champ lointain et en champ proche. Sur la base de l'approche proposée, l'impact de plusieurs paramètres est étudié.Enfin, le Chapitre 5 résume la thèse et discute des perspectives futures qui méritent d'être étudiées pour mieux comprendre les avantages et les inconvénients des RISs pour application aux communications sans filThe emergence of smart radio environment (SRE) as a new paradigm that challenges the status quo in wireless communication has motivated the use of metasurface-based reconfigurable intelligent surface (RIS) to improve the performance limits in wireless communication systems. The main focus of this thesis is the modeling of reconfigurable intelligent surfaces (RIS)-aided communication systems using electromagnetic based methods.Chapter 1 introduces the concept of smart radio environment. We also give the definition of RIS and how RIS can be used in context of SRE. To give some historical perspectives, we also discuss several important milestone papers throughout the development of research activities that lead to the current state of the art.Chapter 2 introduces theoretical concepts that are necessary to understand the results in the subsequent chapters. This chapter is divided into two parts. The first part discusses the metasurfaces modeling where we move from a physics-based microscopic description of a metasurface and introduces a macroscopic representation for it, which is shown to be suitable for application in wireless communications. The second part introduces several analytical approaches that allow us to compute the EM field at any point of a given volume that contains the metasurface.Chapter 3 provides a performance comparison between RISs operating as anomalous reflectors and a decode-and-forward relaying scheme that is representative of competing candidate technologies to realize SREs. The comparison is qualitative and covers multitude metrics. Furthermore, a quantitative comparison in terms of achievable data rates is presented. In particular, the numerical results show that sufficiently large RISs can outperform relay-aided systems in terms of data rate, while reducing the implementation complexity.Chapter 4 proposes an electromagnetic-based analytical characterization of the free-space path-loss of a wireless link in the presence of a RIS that is modeled as a two-dimensional homogenized metasurface made of sub-wavelength scattering elements and that operate either in reflection or transmission mode. The analytical method of physical optics is employed. Closed-form expressions are also obtained in two asymptotic regimes that are representative of far-field and near-field deployments. Based on the proposed approach, the impact of several design parameters and operating regimes is unveiled.Finally, Chapter 5 summarizes the main findings of the thesis and discusses possible future directions that are worth investigating to unlock the full potential of RIS and bring it into practice
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Song, Jian. "A Stochastic Geometry Approach to the Analysis and Optimization of Cellular Networks". Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS545.
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Cette thèse porte principalement sur la modélisation, l'évaluation des performances et l'optimisation au niveau système des réseaux cellulaires de nouvelle génération à l'aide de la géométrie stochastique. En plus, la technologie émergente des surfaces intelligentes reconfigurables (RISs) est étudiée pour l'application aux futurs réseaux sans fil. En particulier, reposant sur un modèle d’abstraction basé sur la loi de Poisson pour la distribution spatiale des nœuds et des points d’accès, cette thèse développe un ensemble de nouveaux cadres analytiques pour le calcul d’importantes métriques de performance, telles que la probabilité de couverture et l'efficacité spectrale potentielle, qui peuvent être utilisés pour l'analyse et l'optimisation au niveau système. Plus spécifiquement, une nouvelle méthodologie d'analyse pour l'analyse de réseaux cellulaires tridimensionnels est introduite et utilisée pour l'optimisation du système. Un nouveau problème d’allocation de ressources est formulé et résolu en combinant pour la première fois géométrie stochastique et programmation non linéaire mixte en nombres entiers. L'impact du déploiement de surfaces réfléchissantes intelligentes sur un réseau sans fil est quantifié à l'aide de processus ponctuels, et les avantages potentiels des RISs contre le relais sont étudiés à l'aide de simulations numériquesThe main focus of this thesis is on modeling, performance evaluation and system-level optimization of next-generation cellular networks by using stochastic geometry. In addition, the emerging technology of Reconfigurable Intelligent Surfaces (RISs) is investigated for application to future wireless networks. In particular, relying on a Poisson-based abstraction model for the spatial distribution of nodes and access points, this thesis develops a set of new analytical frameworks for the computation of important performance metrics, such as the coverage probability and potential spectral efficiency, which can be used for system-level analysis and optimization. More specifically, a new analytical methodology for the analysis of three-dimensional cellular networks is introduced and employed for system optimization. A novel resource allocation problem is formulated and solved by jointly combining for the first time stochastic geometry and mixed-integer non-linear programming. The impact of deploying intelligent reflecting surfaces throughout a wireless network is quantified with the aid of line point processes, and the potential benefits of RISs against relaying are investigated with the aid of numerical simulations
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Praia, João Miguel Rocha. "Um projeto de sistema de comunicações com reconhecimento de contexto para a banda THz". Master's thesis, 2021. http://hdl.handle.net/10071/24172.
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As comunicações na banda Terahertz (THz) são consideradas uma tecnologia crucial para a
transmissão de dados a velocidades ultra-elevadas em sistemas de comunicação sem fios da
futura geração. As extensas larguras de banda disponíveis nas frequências de THz têm o custo
de graves perdas de propagação e limitações de potência, o que resulta em distâncias de
comunicação muito curtas. Superfícies inteligentes reconfiguráveis (RIS) são uma tecnologia
promissora para ultrapassar esta limitação uma vez que têm capacidade para moldar as ondas
THz, ajustando adequadamente as mudanças de fase. Esta dissertação foca-se no estudo de um
sistema eficaz em contexto de ambiente para as comunicações sem fio THz.
Na presente dissertação concebemos um sistema de comunicação sem fios ultra-massivo
de múltiplas entradas e saídas (UM-MIMO) assistido por RIS. Para maximizar a taxa alcançável
do sistema, e ao mesmo tempo que se lida com a grande configuração de problemas que é típica
dos sistemas UM-MIMO assistidos por RIS, é desenvolvido um algoritmo de gradiente
proximal acelerado (APG) de baixa complexidade para o cálculo das mudanças de fase dos
elementos do RIS. Também se considera a pré-codificação híbrida, a qual é necessária para
tornar viável a implementação de comunicações UM-MIMO nos THz, e avalia-se a incidência
de não-idealidades que são típicas na implementação prática do sistema.
Os resultados numéricos demonstram que quanto maior o RIS maior taxa de dados o
sistema alcança, e que o mesmo deve ficar situado na vizinhança do recetor ou do transmissor.
A eficácia do algoritmo proposto também é comprovada, mesmo quando se considera a
quantização realista das mudanças de fase discretas e o conhecimento imperfeito do canal.Terahertz (THz)-band communications are considered a crucial technology for ultrahigh data rate transmission in future-generation wireless communication systems. The extensive available bandwidths at THz frequencies come at the cost of severe propagation losses and power limitations, which results in very short communication distances. Reconfigurable intelligent surfaces are a promising technology to overcome this limitation as they can be used to shape THz waves by adequately adjusting the phase shifts. This dissertation focuses on the study of an effective system for THz wireless communications environment. In this dissertation, we design a RIS-assisted ultra-massive multiple-input multiple-output (UM-MIMO) wireless communication system. To maximize the achievable rate of the system, while coping with the large problem setting that is typical in RIS-aided UM-MIMO systems, a low complexity accelerated proximal gradient (APG) algorithm is developed for computing the phase-shifts of the RIS elements. We also consider the adoption of hybrid precoding which is necessary for viable UM-MIMO THz implementations and evaluate the impact of non-idealities that are typical in practical implementations of the system. Numerical results demonstrate that the larger the RIS is, the higher data rate the system achieves, and that it should be located in the vicinity of the receiver or transmitter. The effectiveness of the proposed algorithm is also proven, even when considering realistic quantization of discrete phase shifts and imperfect channel knowledge.
Capítulos de libros sobre el tema "Surfaces intelligentes reconfigurables (RIS)"
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Zhang, Hongliang, Boya Di, Lingyang Song y Zhu Han. "RIS Aided MIMO Communications". En Reconfigurable Intelligent Surface-Empowered 6G, 19–104. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-73499-2_2.
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Zhang, Hongliang, Boya Di, Lingyang Song y Zhu Han. "RIS Aided RF Sensing and Localization". En Reconfigurable Intelligent Surface-Empowered 6G, 161–251. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-73499-2_4.
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Ihsana Muhammed, P., Yasar Moidutty, N. M. Sreenarayanan y V. M. Meera. "Reconfigurable Intelligent Surface (RIS)-Assisted UAV Cellular Communication". En Unmanned Aerial Vehicle Cellular Communications, 115–35. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-08395-2_6.
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Hu, Xiaoling, Chenxi Liu, Mugen Peng y Caijun Zhong. "Introduction of RIS-Enabled ISAC". En Reconfigurable Intelligent Surface-Enabled Integrated Sensing and Communication in 6G, 1–23. Singapore: Springer Nature Singapore, 2024. http://dx.doi.org/10.1007/978-981-99-8299-8_1.
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Hu, Xiaoling, Chenxi Liu, Mugen Peng y Caijun Zhong. "Angle Information Acquisition in RIS-Enabled ISAC". En Reconfigurable Intelligent Surface-Enabled Integrated Sensing and Communication in 6G, 51–76. Singapore: Springer Nature Singapore, 2024. http://dx.doi.org/10.1007/978-981-99-8299-8_3.
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Hu, Xiaoling, Chenxi Liu, Mugen Peng y Caijun Zhong. "Sensing-Assisted Beamforming in RIS-Enabled ISAC". En Reconfigurable Intelligent Surface-Enabled Integrated Sensing and Communication in 6G, 101–33. Singapore: Springer Nature Singapore, 2024. http://dx.doi.org/10.1007/978-981-99-8299-8_5.
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Hu, Xiaoling, Chenxi Liu, Mugen Peng y Caijun Zhong. "Theoretical Performance Analysis of RIS-Enabled ISAC". En Reconfigurable Intelligent Surface-Enabled Integrated Sensing and Communication in 6G, 25–49. Singapore: Springer Nature Singapore, 2024. http://dx.doi.org/10.1007/978-981-99-8299-8_2.
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Hu, Xiaoling, Chenxi Liu, Mugen Peng y Caijun Zhong. "Delay-Doppler Information Acquisition in RIS-Enabled ISAC". En Reconfigurable Intelligent Surface-Enabled Integrated Sensing and Communication in 6G, 77–100. Singapore: Springer Nature Singapore, 2024. http://dx.doi.org/10.1007/978-981-99-8299-8_4.
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Le, Chi-Bao, Dinh-Thuan Do y Samarendra Nath Sur. "Reconfigurable Intelligent Surface (RIS)-Assisted Wireless Systems: Potentials for 6G and a Case Study". En Advances in Communication, Devices and Networking, 367–78. Singapore: Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-16-2911-2_39.
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Sapkale, Pallavi y Shilpa Mehta. "Integration of Reconfigurable Intelligent Surfaces With Antennas for 6G Wireless Communications". En Radar and RF Front End System Designs for Wireless Systems, 112–32. IGI Global, 2024. http://dx.doi.org/10.4018/979-8-3693-0916-2.ch005.
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The evolution of wireless communication networks towards 6G demands innovative solutions to address the challenges of increasing data rates, network capacity, and energy efficiency. Reconfigurable intelligent surfaces (RIS) emerge as a promising technology that revolutionizes how wireless signals propagate and interact with the environment. In this chapter, the authors explore the integration of RIS with antennas for 6G wireless communications. RIS, comprised of programmable meta-surfaces, can dynamically manipulate electromagnetic waves to optimize signal quality, mitigate interference, and enhance network performance. By providing adaptive beam forming, beam steering, and signal enhancement capabilities, RIS-enabled antennas offer unprecedented flexibility and efficiency in communication systems. This chapter overviews RIS principles, discusses their integration with antennas, and highlights their potential to shape the future of 6G wireless communications.
Actas de conferencias sobre el tema "Surfaces intelligentes reconfigurables (RIS)"
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Amri, Muhammad Miftahul. "Recent Trends in the Reconfigurable Intelligent Surfaces (RIS): Active RIS to Brain-controlled RIS". En 2022 IEEE International Conference on Communication, Networks and Satellite (COMNETSAT). IEEE, 2022. http://dx.doi.org/10.1109/comnetsat56033.2022.9994338.
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Yazdani, Reza, Manish Kizhakkeveettil Mathew, Zhekun Peng y DongHyun Kim. "Reconfigurable Intelligent Surface (RIS) Design for 5G n260 Frequency Band". En 2023 IEEE Symposium on Electromagnetic Compatibility & Signal/Power Integrity (EMC+SIPI). IEEE, 2023. http://dx.doi.org/10.1109/emcsipi50001.2023.10241407.
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Eddine Zegrar, Salah, Liza Afeef y Huseyin Arslan. "Reconfigurable intelligent surface (RIS): Eigenvalue Decomposition-Based Separate Channel Estimation". En 2021 IEEE 32nd Annual International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC). IEEE, 2021. http://dx.doi.org/10.1109/pimrc50174.2021.9569501.
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Sadia, Haleema, Ziaul Haq Abbas, Ahmad Kamal Hassan y Ghulam Abbas. "Outage Probability Analysis of Reconfigurable Intelligent Surface (RIS)-Enabled NOMA Network". En 2023 10th International Conference on Wireless Networks and Mobile Communications (WINCOM). IEEE, 2023. http://dx.doi.org/10.1109/wincom59760.2023.10322994.
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Youn, Youngno, Donggeun An, Daehyeon Kim, Myeonggin Hwang y Wonbin Hong. "Cognitive Reconfigurable Intelligent Surface (RIS) for mmWave Integrated Sensing and Communication". En 2023 IEEE International Symposium On Antennas And Propagation (ISAP). IEEE, 2023. http://dx.doi.org/10.1109/isap57493.2023.10389072.
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Huang, Yiqian, Saviour Zammit, Ping Yang, Yue Xiao, Bo Zhang, Jienan Chen y Wei Xiang. "Over-the-RIS Modulation: A Reconfigurable Intelligent Surface Assisted Modulation Design". En 2023 8th International Conference on Communication, Image and Signal Processing (CCISP). IEEE, 2023. http://dx.doi.org/10.1109/ccisp59915.2023.10355851.
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Ouyang, Chongjun, Hao Xu, Xujie Zang y Hongwen Yang. "On the Ergodic Capacity of Reconfigurable Intelligent Surface (RIS)-Aided MIMO Channels". En 2022 IEEE 96th Vehicular Technology Conference (VTC2022-Fall). IEEE, 2022. http://dx.doi.org/10.1109/vtc2022-fall57202.2022.10012964.
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Zhao, Qichao, Wenfei Gong, Tianwei Hou, Xin Sun y Eliane Bodanese. "Global Navigation Satellite System (GNSS): A Reconfigurable Intelligent Surface (RIS)-aided Approach". En GLOBECOM 2022 - 2022 IEEE Global Communications Conference. IEEE, 2022. http://dx.doi.org/10.1109/globecom48099.2022.10001462.
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Zhao, Qichao, Wenfei Gong, Tianwei Hou, Xin Sun, Anna Li y Eliane Bodanese. "Integrated-Navigation-and-Communication (INAC): A Reconfigurable Intelligent Surface (RIS)-aided Approach". En 2023 IEEE 97th Vehicular Technology Conference (VTC2023-Spring). IEEE, 2023. http://dx.doi.org/10.1109/vtc2023-spring57618.2023.10199514.
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Dong, Limeng y Wanyu Yan. "Active Reconfigurable Intelligent Surface (RIS) Aided Secure Wireless Transmission Under a Shared Power Source Between Transmitter and RIS". En 2022 14th International Conference on Wireless Communications and Signal Processing (WCSP). IEEE, 2022. http://dx.doi.org/10.1109/wcsp55476.2022.10039260.
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