Letteratura scientifica selezionata sul tema "Passive Beamforming"
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Articoli di riviste sul tema "Passive Beamforming"
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Gao, Jiabao, Caijun Zhong, Xiaoming Chen, Hai Lin e Zhaoyang Zhang. "Unsupervised Learning for Passive Beamforming". IEEE Communications Letters 24, n. 5 (maggio 2020): 1052–56. http://dx.doi.org/10.1109/lcomm.2020.2965532.
Testo completo
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Di Martino, Gerardo, e Antonio Iodice. "Passive beamforming with coprime arrays". IET Radar, Sonar & Navigation 11, n. 6 (giugno 2017): 964–71. http://dx.doi.org/10.1049/iet-rsn.2016.0517.
Testo completo
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Jung, Minchae, Taehyoung Kim e Hyukmin Son. "Performance Analysis of RIS-Assisted SatComs Based on a ZFBF and Co-Phasing Scheme". Mathematics 12, n. 8 (21 aprile 2024): 1257. http://dx.doi.org/10.3390/math12081257.
Testo completoAbstract (sommario):
In recent high-throughput satellite communication (SatCom) systems, the use of reconfigurable intelligent surfaces (RISs) has emerged as a promising solution to improve spectral efficiency and extend coverage in areas with limited terrestrial network access. However, the RIS may amplify the inter-beam interference (IBI) caused by multibeam transmission at the satellite, and multiple RISs can also cause inter-RIS interference (IRI) to terrestrial users. In this paper, the performance of the RIS-assisted SatCom system is asymptotically analyzed for both full and partial channel state information (CSI) scenarios. In particular, zero-forcing beamforming is considered as the active beamforming for data transmission, while the co-phasing scheme is considered as the passive beamforming for RIS reflection. Based on the asymptotic analyses, deterministic active and passive beamforming techniques using partial CSI are proposed that can gradually eliminate both IBI and IRI, ultimately achieving ideal performance. Simulation results validate the accuracy of asymptotic analyses and demonstrate the superiority of deterministic active and passive beamforming techniques using partial CSI. The simulation results also confirm that the proposed beamforming can achieve approximately 92.8% of the ideal performance, even though it only requires partial CSI.
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Gao, Chuanzhe, Shidang Li, Yixuan Wu, Siyi Duan, Mingsheng Wei e Bencheng Yu. "Power-Efficient Resource Allocation for Active STAR-RIS-Aided SWIPT Communication Systems". Future Internet 16, n. 8 (25 luglio 2024): 266. http://dx.doi.org/10.3390/fi16080266.
Testo completoAbstract (sommario):
Simultaneous wireless information and power transfer (SWIPT) has emerged as a pivotal technology in 6G, offering an efficient means of delivering energy to a large quantity of low-power devices while transmitting data concurrently. To address the challenges of obstructions, high path loss, and significant energy consumption associated with long-distance communication, this work introduces a novel alternating iterative optimization strategy. The proposed approach combines active simultaneous transmission and reflection of reconfigurable intelligent surfaces (STAR-RIS) with SWIPT to maximize spectrum efficiency and reduce overall system energy consumption. This method addresses the considerable energy demands inherent in SWIPT systems by focusing on reducing the power output from the base station (BS) while meeting key constraints: the communication rate for information receivers (IRs) and minimum energy levels for energy receivers (ERs). Given complex interactions between variables, the solution involves an alternating iterative optimization process. In the first stage of this approach, the passive beamforming variables are kept constant, enabling the use of semi-definite relaxation (SDR) and successive convex approximation (SCA) algorithms to optimize active beamforming variables. In the next stage, with active beamforming variables fixed, penalty-based algorithms are applied to fine-tune the passive beamforming variables. This iterative process continues, alternating between active and passive beamforming optimization, until the system converges on a stable solution. The simulation results indicated that the proposed system configuration, which leverages active STAR-RIS, achieves lower energy consumption and demonstrates improved performance compared to configurations utilizing passive RIS, active RIS, and passive STAR-RIS. This evidence suggests that the proposed approach can significantly contribute to advancing energy efficiency in 6G systems.
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Zhao, Ke, Zhiqun Song, Yong Li, Xingjian Li, Lizhe Liu e Bin Wang. "A Deep Evolution Policy-Based Approach for RIS-Enhanced Communication System". Entropy 26, n. 12 (5 dicembre 2024): 1056. https://doi.org/10.3390/e26121056.
Testo completoAbstract (sommario):
This paper investigates the design of active and passive beamforming in a reconfigurable intelligent surface (RIS)-aided multi-user multiple-input single-output (MU-MISO) system with the objective of maximizing the sum rate. We propose a deep evolution policy (DEP)-based algorithm to derive the optimal beamforming strategy by generating multiple agents, each utilizing distinct deep neural networks (DNNs). Additionally, a random subspace selection (RSS) strategy is incorporated to effectively balance exploitation and exploration. The proposed DEP-based algorithm operates without the need for alternating iterations, gradient descent, or backpropagation, enabling simultaneous optimization of both active and passive beamforming. Simulation results indicate that the proposed algorithm can bring significant performance enhancements.
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Zhang, Wenjuan, Honggui Deng, Youzhen Li, Zaoxing Zhu, Chengzuo Peng e Gang Liu. "Beamforming Optimization for Intelligent Reflecting Surface-Assisted MIMO Systems". Symmetry 14, n. 8 (23 luglio 2022): 1510. http://dx.doi.org/10.3390/sym14081510.
Testo completoAbstract (sommario):
To improve the spectral efficiency of symmetry-based intelligent reconfigurable surface (IRS)-assisted MIMO communication systems, this paper investigates the joint precoding and passive beamforming optimization problem for millimeter-wave point-to-point MIMO systems under both ideal and practical IRS phase shifts. For the ideal IRS phase shifts setup, we derive a simplified approximate spectral efficiency expression based on Jensen’s inequality and propose a minimum mean square error (MMSE)-based algorithm to transform the simplified non-convex problem into a solvable convex function. For the practical IRS phase shifts setup, we propose a multi-start stepwise optimization algorithm to obtain the passive beamforming by stepwise iterative search. Finally, with the above-obtained passive beamforming, the optimal precoding is derived by performing the singular value decomposition (SVD) on the effective channel and water-filling power allocation. The simulation results verify our performance analysis and demonstrate that spectral efficiency can be effectively improved compared to various benchmark schemes.
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Liu, Shijing, Fusheng Gong, Yuebo Li e Xiangbo Sun. "Kalman filtering used for passive synthetic aperture". Journal of Physics: Conference Series 2756, n. 1 (1 maggio 2024): 012013. http://dx.doi.org/10.1088/1742-6596/2756/1/012013.
Testo completoAbstract (sommario):
Abstract In practice, beamforming-based bearing estimators typically fail to account for the impact of environmental factors on the estimating results, resulting in the so-called mismatch problem. To deal with this issue, this paper reconstructs the bearing estimation as a Kalman filter problem, which emphasizes the role of physical models in underwater acoustic signal processing. Since passive synthetic aperture (PSA) is a spatial process including the temporal evolution of a moving array, it fits a Kalman filtering structure. Kalman filter is applied directly to a lake-test dataset collected by an autonomous underwater vehicle (AUV) shell-mounted array, and the experimental findings demonstrate that the bearing estimation results’ variation is significantly decreased than the conventional beamforming (CBF).
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Qian, Yuyan, Honggui Deng, Aimin Guo, Haoqi Xiao, Chengzuo Peng e Yinhao Zhang. "Beamforming Design for Cooperative Intelligent Reflecting Surface-Assisted mmWave Communication". Sensors 22, n. 16 (18 agosto 2022): 6214. http://dx.doi.org/10.3390/s22166214.
Testo completoAbstract (sommario):
In order to investigate the effect of cooperative Intelligent Reflecting Surface (IRS) in improving spectral efficiency, this paper explores the joint design of active and passive beamforming based on a double IRS-assisted model. First, considering the maximum power constraint of the active vector and the unit modulus constraint of the cooperative passive vector, we establish the non-linear and non-convex optimization problem of multi-user maximization weighted sum rate (WSR). Then, we propose an alternating optimization (AO) algorithm to design the active vector and the cooperative passive vector based on fractional programming (FP) and successive convex approximations (SCA). In addition, we conduct a study on the optimization of the passive reflection vector under discrete phase shift. The simulation results show that the proposed beamforming scheme of double IRS-assisted model performs better than the conventional single IRS-assisted model.
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Somasundaram, Samuel D. "Wideband Robust Capon Beamforming for Passive Sonar". IEEE Journal of Oceanic Engineering 38, n. 2 (aprile 2013): 308–22. http://dx.doi.org/10.1109/joe.2012.2223560.
Testo completo
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Abadi, Shima H., Kevin J. Haworth, Karla P. Mercado-Shekhar e David R. Dowling. "Frequency-sum beamforming for passive cavitation imaging". Journal of the Acoustical Society of America 144, n. 1 (luglio 2018): 198–209. http://dx.doi.org/10.1121/1.5045328.
Testo completoTesi sul tema "Passive Beamforming"
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Cremer, Markus. "Digital beamforming techniques for passive UHF RFID tag localization". Thesis, London South Bank University, 2016. http://researchopen.lsbu.ac.uk/1819/.
Testo completoAbstract (sommario):
Radio-frequency identification (RFID) technology is on the way to substitute traditional bar codes in many fields of application. Especially the availability of passive ultra-high frequency (UHF) RFID transponders (or tags) in the frequency band between 860 MHz and 960 MHz has fostered the global application in supply chain management. However, the full potential of these systems will only be exploited if the identification of objects is complemented by accurate and robust localization. Passive UHF RFID tags are cost-effective, very small, extremely lightweight, maintenancefree, rugged and can be produced as adhesive labels that can be attached to almost any object. Worldwide standards and frequency regulations have been established and a wide infrastructure of identification systems is operated today. However, the passive nature of the technology requires a simple communication protocol which results in two major limitations with respect to its use for localization purposes: the small signal bandwidth and the small allocated frequency bandwidth. In the presence of multipath reflections, these limitations reduce the achievable localization accuracy and reliability. Thus, new methods have to be found to realize passive UHF RFID localization systems which provide sufficient performance in typical multipath situations. In this thesis, an enhanced transmission channel model for passive UHF RFID localization systems has been proposed which allows an accurate estimation of the channel behaviour to multipath. It has been used to design a novel simulation environment and to identify three solutions to minimize multipath interference: a) by varying the channel interface parameters, b) by applying diversity techniques, c) by installation of UHF absorbers. Based on the enhanced channel model, a new method for tag readability prediction with high reliability has been introduced. Furthermore, a novel way to rate the magnitude of multipath interference has been proposed. A digital receiver beamforming localization method has been presented which uses the Root MUSIC algorithm for angulation of a target tag and multipath reducing techniques for an optimum localization performance. A new multiangulation algorithm has been proposed to enable the application of diversity techniques. A novel transmitter beamforming localization approach has been presented which exploits the precisely defined response threshold of passive tags in order to achieve high robustness against multipath. The basic technique has been improved significantly with respect to angular accuracy and processing times. Novel experimental testbeds for receiver and transmitter beamforming have been designed, built and used for verification of the localization performance in real-world measurements. All the improvements achieved contribute to an enhancement of the accuracy and especially the robustness of passive UHF RFID localization systems in multipath environments which is the main focus of this research.
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Gebbie, John Thomas. "Advances in Aquatic Target Localization with Passive Sonar". PDXScholar, 2014. https://pdxscholar.library.pdx.edu/open_access_etds/1932.
Testo completoAbstract (sommario):
New underwater passive sonar techniques are developed for enhancing target localization capabilities in shallow ocean environments. The ocean surface and the seabed act as acoustic mirrors that reflect sound created by boats or subsurface vehicles, which gives rise to echoes that can be heard by hydrophone receivers (underwater microphones). The goal of this work is to leverage this "multipath" phenomenon in new ways to determine the origin of the sound, and thus the location of the target. However, this is difficult for propeller driven vehicles because the noise they produce is both random and continuous in time, which complicates its measurement and analysis. Further, autonomous underwater vehicles (AUVs) pose additional challenges because very little is known about the sound they generate, and its similarity to that of boats. Existing methods for localizing propeller noise using multiple hydrophones have approached the problem either purely theoretically, or empirically such as by analyzing the interference patterns between multipath arrivals at different frequencies, however little has been published on building localization techniques that directly measure and utilize the time delays between multipath arrivals while simultaneously accounting for relevant environmental parameters. This research develops such techniques through a combination of array beamforming and advanced ray-based modeling that account for variations in bathymetry (seabed topography) as well as variations of the sound speed of the water. The basis for these advances come from several at-sea experiments in which different configurations of passive sonar systems recorded sounds emitted by different types of targets, including small boats and an autonomous underwater vehicle. Ultimately, these contributions may reduce the complexity and cost of passive systems that need to be deployed close to shore, such as for harbor security applications. Further, they also create new possibilities for applying passive sonar in remote ocean regions for tasks such as detecting illegal fishing activity.
This dissertation makes three key contributions:
1. Analysis of the aspect-dependent acoustic radiation patterns of an underway autonomous underwater vehicle (AUV) through full-field wave modeling.
2. A two-hydrophone cross-correlation technique that leverages multipath as well as bathymetric variations to estimate the range and bearing of a small boat, supported by a mathematically rigorous performance analysis.
3. A multi-target localization technique based on directly measuring multipath from multiple small surface vessels using a small hydrophone array mounted to the nose of an AUV, which operates by cross-correlating two elevation beams on a single bearing.
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Chmiel, Malgorzata. "Traitement de données géophysiques en réseaux denses en configuration sismique passive et active". Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAU009/document.
Testo completoAbstract (sommario):
En géophysique, les réseaux denses améliorent la caractérisation spatiale et fréquentielle des différents types d’ondes dans le milieu. Bien entendu, l’acquisition en surface est sujette aux ondes de surface qui sont très fortes. Les ondes de surface ont un fort impact sur les données géophysiques acquises au niveau du sol. Elles peuvent être considérées comme du bruit et être sujettes à la suppression puisqu’elles cachent l’information de sous-surface. Cependant, elles peuvent être utiles pour l’imagerie de proche surface si elles sont convenablement récupérées.Dans tous les cas, leur caractérisation est cruciale en géophysique d’exploration active et passive. Dans la surveillance microsismique passive, le bruit de surface ambiant est composé d’ondes de surface. L’objectif principal de la surveillance passive est de minimiser l’impact des ondes de surface sur les données microsismiques. Le fort bruit de surface diminue la sensibilité etl’efficacité des méthodes de détection et de localisation. De plus, les méthodes actuelles de localisation et de détection nécessitent généralement la connaissance d’informations telles qu’un un modèle de vitesse ou un modèle d’événement. Dans la sismique active, de fortes ondes de surface sont générés par des sources actives. Les stratégies actuelles de traitement sont généralement basées sur une sélection manuelle des ondes de surface afin de choisir lesquelles garder. Il s’agit là d’une tâche complexe, coûteuse et sujette à interprétation. Cependant, cette tâche est nécessaire pour l’imagerie de proche-surface et de sous-surface. Les ondes de surface peuvent être particulièrement difficiles à récupérer dans des acquisitions clairsemées.Nous proposons d’appliquer les techniques d’interférométrie et de formation de voies (telles que le Matched Field Processing) dans le contexte des réseaux denses. Une densité de traces importante ouvre de nouvelles possibilités dans les traitements géophysiques, qu’ils soient actifs ou passifs. Nous montrons que le bruit ambiant peut être utilisé dans le traitement microsismique pour extraire des informations importantes sur les propriétés du milieu. De plus, nous développons une approche de débruitage qui permet de supprimer les sources de bruit à la surface et détecter les événements microsismiques. Nous proposons également une méthode automatique de détection et de localisation qui se base sur une quantité minimale d’information préalable qui permet de récupérer la distribution des hétérogénéités du réservoir, dans le voisinage du puits. En ce qui concerne la sismique active, nous proposons une approche interférométrique et automatique de caractérisation des ondes de surface. Nous récupérons les noyaux de sensibilité de phase des ondes de surface entre deux points quelconques de l’acquisition. Ces noyaux de sensibilité sont par conséquent utilisés pour obtenir les courbes de dispersion multimodales. Ces courbes de dispersion permettent la séparation des différents modes des ondes de surface, et fournissent l’information de proche surface suite à une simple inversion.Le réseau dense permet l’amélioration des méthodes présentées ci-dessus: elle permet des applications alternatives et innovantes dans le traitement du signal géophysiqueIn geophysics, spatially dense arrays enhance the spatial and frequential characterization of the various waves propagating in the medium. Of course, surface array is subject to strong surface waves. Surface waves highly impact the processing of geophysical data acquired at ground level. They can be considered as noise and subject to suppression as they mask sub-surface information.However, they can be useful for near-surface imaging if they are well retrieved. In any case, their characterization is crucial in active and passive exploration geophysics. In passive microseismic monitoring, ambient surface noise consists of surface waves. The main goal of passive monitoring is to minimize the impact of surface waves on the actual microseismic data. The strong ambient surface noise lowers the sensitivity and the efficiency ofdetection and location methods. Moreover, current location and detection methods usually require strong a priori information (e.g., a velocity model or a template).Active sources generate strong surface waves. In active seismic, current processing strategies often consist in manually picking surface wave arrivals in order to use or remove them. This is often a complex, time consuming, and an ambiguous task. However, it is needed for near- and sub-surface imaging. Surface waves can be particularly difficult to retrieve in sparse arrays. We propose to apply the techniques of interferometry and beamforming (Matched Field Processing in particular) in the context of dense arrays. High trace density opens new possibilities in geophysical processing in both passive and active surveys. We show that the ambient noise can be explored in the case of microseismic monitoring to extract important information about the medium properties. Moreover, we develop a denoising approach to remove the noise sources at the surface and detect the microseismic event. Furthermore, we propose an automatic detection and location method with a minimum a priori information to retrieve the distribution of heterogeneities in the reservoir, in the well vicinity.In active survey, we propose an interferometric, automatic approach to characterize the surface waves. We retrieve phase-sensitivity kernels of surface waves between any two points of the acquisition. These kernels are consequently used to obtain multi-mode dispersion curves. These dispersion curves make it possible to separate different modes of surface waves and provide near-surface information if inverted.The above presented methodologies benefit from spatially dense arrays.Dense arrays of sources or receivers enable alternative, innovative applications in geophysical processing
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Browning, Kyle C. "Passive and Electronically Steered Array Planar Feeds for Satellite Communications". BYU ScholarsArchive, 2014. https://scholarsarchive.byu.edu/etd/3961.
Testo completoAbstract (sommario):
As the need for more bandwidth increases, satellite communication (SatCom) terminals are forced to climb higher in frequency. Higher frequency means greater propagation losses, and so antenna gain and sensitivity have to increase. The higher the gain, the more difficult it is to point the antenna. To make matters even more challenging, consumers are requesting satellite links in harsher environments and on moving vehicle and planes. In order to meet today's challenges and improve on dish feeds, research is ongoing to replace fixed-beam feedhorns with smaller, cheaper, and lighter PCB based antennas and to develop low-cost electronically steered array feeds (ESAF). ESAFs will not only improve the signal link, but they will also aid in pointing the antenna and then tracking the satellite independent of movement. Here is presented some of the first planar antenna dish feeds developed by the Brigham Young University's SatCom Group. Included are the simulation and test procedures to determine if they are viable for SatCom use. The results show that these antennas make significant advancements in efficiencies and prove a path forward to a feedhorn replacement. Several planar designs are presented, each with a unique solution to meet all the requirements for a dish feed. Also presented is the first low-cost ESAFs developed to give commercial SatCom an electronically steerable dish. None of the designed hardware requires a redesign of current modems and receiver boxes. The research looks at keeping costs low by minimizing the required electronics. This further led to researching the limits on how simple the electronics could be. The ESAF doubled the visible area of the dish and successfully acquired and tracked a satellite as the dish moved. The ESAF also demonstrates a path forward to increase the steerable range and improve pointing and tracking.
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Sadok, Mustapha. "Exploitation de la non-circularité pour les transmissions et l'écoute passive". Thesis, Evry, Institut national des télécommunications, 2017. http://www.theses.fr/2017TELE0019/document.
Testo completoAbstract (sommario):
Cette thèse est consacrée à l’exploitation des propriétés de non-circularité et de non-gaussianité des signaux d’intérêt (SOI) et/ou des interférences pour les transmissions sans fil et l’écoute passive. Dans une première partie de cette thèse, nous nous intéressons à l’extension des récepteurs SIMO-MLSE conventionnels vers de nouvelles architectures exploitant la potentielle non-circularité au second ordre des interférences co-canal (CCI), pour la démodulation de signaux rectilignes (BPSK, ASK), quasi-rectilignes (MSK, GMSK et OQAM) et à symboles complexes (QAM). L’architecture générale des récepteurs développés est basée sur un prétraitement avec une extension widely linear (WL) du filtre adapté spatio-temporel, ramenant le traitement de démodulation à un problème scalaire, un échantillonnage au rythme symbole et ensuite un organe de décision basé sur une version modifiée de l’algorithme de Viterbi. Pour le cas particulier des signaux quasi-rectiligne, on intercale un traitement de dérotation entre l’échantillonneur et l’organe de décision. Un travail de modélisation à temps discret des SOI, brouilleurs et du bruit de fond a été mené afin de créer des modèles de simulations pour la validation des expressions SINR analytiques interprétables, via l’évaluation des probabilités d’erreur symboles. Dans une deuxième partie, nous nous intéressons à la formation de voies (Beamforming) non-linéaire à travers des structures de Volterra complexe du troisième ordre. Ces dernières permettent l’exploitation de la non-circularité jusqu’au sixième ordre ainsi que du caractère non-gaussien des SOI et/ou des interférences. Dans le contexte de l’écoute passive, nous avons introduit un beamformer MVDR de Volterra du troisième ordre utilisant la seule information a priori du vecteur directionnel du SOI et implémentable grâce à une structure équivalente GSC. Nous avons étudié ses performances en particulier par l’évaluation analytique des expressions du SINR en fonction des statistiques de l’interférence, et par sa vitesse d’apprentissage, démontrant ainsi sa supériorité par rapport aux beamformers MVDR linéaire et WL classiques. Dans un contexte de radiocommunications, nous avons étudié une version MMSE de ce beamformer de Volterra complexe du troisième ordre qui prend lui en compte les propriétés statistiques de non-circularité jusqu’au sixième ordre et de non-gaussianité du SOI et du CCI. La dernière partie de cette thèse est consacrée à la robustesse de tests de détection de rectilinéarité de signaux en présente d’offsets de fréquence. Ces tests sont importants pour ajuster la nature du traitement (linéaire ou WL) en fonction de la rectilinéarité des signaux, afin de garantir le meilleur rapport performance/temps de convergence des algorithmesThis thesis is devoted to exploit the non-circularity and non-gaussianity properties of signals of interest (SOI) and/or interference for wireless transmissions and passive listening. In the first part of this thesis, we are interested in the extension of conventional SIMO-MLSE receivers to new architectures exploiting the potential second order non-circularity of co-channel interference (CCI), for the demodulation of rectilinear signals (BPSK, ASK), quasi-rectilinear (MSK, GMSK and OQAM) and quadrature amplitude modulation (QAM). The general architecture of the developed receivers is based on a pre-processing with a widely linear (WL) extension of the spatio-temporal matched filter, bringing the demodulation processing back to a scalar problem, a sampling at the symbol rate and then a decision block based on a modified version of the Viterbi algorithm. For the particular case of the quasi-rectilinear signals, a derotation processing is interposed between the sampler and the decision block. A work on equivalent discrete time modeling of SOI, interferers and background noise has been carried out in order to create simulation models as for the validation of the interpretable analytic SINR expressions, by the evaluation of the symbol error rates. In a second part, we are interested to the beamforming through complex Volterra structures of the third order. These structures allow us the exploitation of the non-circularity up to the sixth order as well as the non-gaussian nature of the SOI and/or the interferences. For passive listening applications, we have introduced a third-order Volterra MVDR beamformer using only a priori information of SOI steering vector and implemented by an equivalent GSC structure. We have studied its performance, in particular by interpretable closed-form expressions as functions of statistics of the interference, and by its speed of learning, thus proving its advantages with respect to the conventional linear and WL MVDR beamformers. For wireless communications applications, we have studied an MMSE version of this complex Volterra beamformer of the third order that takes into account of the non-circularity up to the sixth order as well as the non-gaussian nature of the SOI and interference. The last part of this thesis is devoted to the robustness of rectilinearity tests in the presence of frequency offset. These tests are important for adjusting the processing (linear or WL) as a function of the rectilinearity of the signals in order to guarantee the best performance/convergence rate ratio of algorithms
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Lepkowski, Stefan. "An ultra-compact and low loss passive beamforming network integrated on chip with off chip linear array". Thesis, Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/53599.
Testo completoAbstract (sommario):
The work here presents a review of beam forming architectures. As an example, the author presents an 8x8 Butler Matrix passive beam forming network including the schematic, design/modeling, operation, and simulated results. The limiting factor in traditional beam formers has been the large size dictated by transmission line based couplers. By replacing these couplers with transformer-based couplers, the matrix size is reduced substantially allowing for on chip compact integration. In the example presented, the core area, including the antenna crossover, measures 0.82mm×0.39mm (0.48% the size of a branch line coupler at the same frequency). The simulated beam forming achieves a peak PNR of 17.1 dB and 15dB from 57 to 63GHz. At the 60GHz center frequency the average insertion loss is simulated to be 3.26dB. The 8x8 Butler Matrix feeds into an 8-element antenna array to show the array patterns with single beam and adjacent beam isolation.
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Muzi, Lanfranco. "Advances in Autonomous-Underwater-Vehicle Based Passive Bottom-Loss Estimation by Processing of Marine Ambient Noise". PDXScholar, 2015. https://pdxscholar.library.pdx.edu/open_access_etds/2612.
Testo completoAbstract (sommario):
Accurate modeling of acoustic propagation in the ocean waveguide is important to SONAR-performance prediction, and requires, particularly in shallow water environments, characterizing the bottom reflection loss with a precision that databank-based modeling cannot achieve. Recent advances in the technology of autonomous underwater vehicles (AUV) make it possible to envision a survey system for seabed characterization composed of a short array mounted on a small AUV. The bottom power reflection coefficient (and the related reflection loss) can be estimated passively by beamforming the naturally occurring marine ambient-noise acoustic field recorded by a vertical line array of hydrophones. However, the reduced array lengths required by small AUV deployment can hinder the process, due to the inherently poor angular resolution. In this dissertation, original data-processing techniques are presented which, by introducing into the processing chain knowledge derived from physics, can improve the performance of short arrays in this particular task. Particularly, the analysis of a model of the ambient-noise spatial coherence function leads to the development of a new proof of the result at the basis of the bottom reflection-loss estimation technique. The proof highlights some shortcomings inherent in the beamforming operation so far used in this technique. A different algorithm is then proposed, which removes the problem achieving improved performance. Furthermore, another technique is presented that uses data from higher frequencies to estimate the noise spatial coherence function at a lower frequency, for sensor spacing values beyond the physical length of the array. By "synthesizing" a longer array, the angular resolution of the bottom-loss estimate can be improved, often making use of data at frequencies above the array design frequency, otherwise not utilized for beamforming. The proposed algorithms are demonstrated both in simulation and on real data acquired during several experimental campaigns.
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Remillieux, Marcel Christophe. "Aeroacoustic Study of a Model-Scale Landing Gear in a Semi-Anechoic Wind Tunnel". Thesis, Virginia Tech, 2007. http://hdl.handle.net/10919/31674.
Testo completoAbstract (sommario):
An aeroacoustic study was conducted on a 26%-scale Boeing 777 main landing gear in the Virginia Tech (VT) Anechoic Stability Wind Tunnel. The VT Anechoic Stability Wind Tunnel allowed noise measurements to be carried out using both a 63-elements microphone phased array and a linear array of 15 microphones. The noise sources were identified from the flyover view under various flow speeds and the phased array positioned in both the near and far-field. The directivity pattern of the landing gear was determined using the linear array of microphones. The effectiveness of 4 passive noise control devices was evaluated. The 26%-scale model tested was a faithful reproduction of the full-scale landing gear and included most of the full-scale details with accuracy down to 3 mm. The same landing gear model was previously tested in the original hard-walled configuration of the VT tunnel with the same phased array mounted on the wall of the test section, i.e. near-field position. Thus, the new anechoic configuration of the VT wind tunnel offered a unique opportunity to directly compare, using the same gear model and phased array instrumentation, data collected in hard-walled and semi-anechoic test sections.
The main objectives of the present work were (i) to evaluate the validity of conducting aeroacoustic studies in non-acoustically treated, hard-walled wind tunnels, (ii) to test the effectiveness of various streamlining devices (passive noise control) at different flyover locations, and (iii) to assess if phased array measurements can be used to estimate noise reduction.
As expected, the results from this work show that a reduction of the background noise (e.g. anechoic configuration) leads to significantly cleaner beamforming maps and allows one to locate noise sources that would not be identified otherwise. By using the integrated spectra for the baseline landing gear, it was found that in the hard-walled test section the levels of the landing gear noise were overestimated.
Phased array measurements in the near and far-field positions were also compared in the anechoic configuration. The results showed that straight under the gear, near-field measurements located only the lower-truck noise sources, i.e. noise components located behind the truck were shielded. It was thus demonstrated that near-field, phased-array measurements of the landing gear noise straight under the gear are not suitable. The array was also placed in the far-field, on the rear-arc of the landing gear. From this position, other noise sources such as the strut could be identified. This result demonstrated that noise from the landing gear on the flyover path cannot be characterized by only taking phased array measurement right under the gear.
The noise reduction potential of various streamlining devices was estimated from phased array measurements (by integrating the beamforming maps) and using the linear array of individually calibrated microphones. Comparison of the two approaches showed that the reductions estimated from the phased array and a single microphone were in good agreement in the far-field. However, it was found that in the near-field, straight under the gear, phased array measurements greatly overestimate the attenuation.Master of Science
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Sadok, Mustapha. "Exploitation de la non-circularité pour les transmissions et l'écoute passive". Electronic Thesis or Diss., Evry, Institut national des télécommunications, 2017. http://www.theses.fr/2017TELE0019.
Testo completoAbstract (sommario):
Cette thèse est consacrée à l’exploitation des propriétés de non-circularité et de non-gaussianité des signaux d’intérêt (SOI) et/ou des interférences pour les transmissions sans fil et l’écoute passive. Dans une première partie de cette thèse, nous nous intéressons à l’extension des récepteurs SIMO-MLSE conventionnels vers de nouvelles architectures exploitant la potentielle non-circularité au second ordre des interférences co-canal (CCI), pour la démodulation de signaux rectilignes (BPSK, ASK), quasi-rectilignes (MSK, GMSK et OQAM) et à symboles complexes (QAM). L’architecture générale des récepteurs développés est basée sur un prétraitement avec une extension widely linear (WL) du filtre adapté spatio-temporel, ramenant le traitement de démodulation à un problème scalaire, un échantillonnage au rythme symbole et ensuite un organe de décision basé sur une version modifiée de l’algorithme de Viterbi. Pour le cas particulier des signaux quasi-rectiligne, on intercale un traitement de dérotation entre l’échantillonneur et l’organe de décision. Un travail de modélisation à temps discret des SOI, brouilleurs et du bruit de fond a été mené afin de créer des modèles de simulations pour la validation des expressions SINR analytiques interprétables, via l’évaluation des probabilités d’erreur symboles. Dans une deuxième partie, nous nous intéressons à la formation de voies (Beamforming) non-linéaire à travers des structures de Volterra complexe du troisième ordre. Ces dernières permettent l’exploitation de la non-circularité jusqu’au sixième ordre ainsi que du caractère non-gaussien des SOI et/ou des interférences. Dans le contexte de l’écoute passive, nous avons introduit un beamformer MVDR de Volterra du troisième ordre utilisant la seule information a priori du vecteur directionnel du SOI et implémentable grâce à une structure équivalente GSC. Nous avons étudié ses performances en particulier par l’évaluation analytique des expressions du SINR en fonction des statistiques de l’interférence, et par sa vitesse d’apprentissage, démontrant ainsi sa supériorité par rapport aux beamformers MVDR linéaire et WL classiques. Dans un contexte de radiocommunications, nous avons étudié une version MMSE de ce beamformer de Volterra complexe du troisième ordre qui prend lui en compte les propriétés statistiques de non-circularité jusqu’au sixième ordre et de non-gaussianité du SOI et du CCI. La dernière partie de cette thèse est consacrée à la robustesse de tests de détection de rectilinéarité de signaux en présente d’offsets de fréquence. Ces tests sont importants pour ajuster la nature du traitement (linéaire ou WL) en fonction de la rectilinéarité des signaux, afin de garantir le meilleur rapport performance/temps de convergence des algorithmesThis thesis is devoted to exploit the non-circularity and non-gaussianity properties of signals of interest (SOI) and/or interference for wireless transmissions and passive listening. In the first part of this thesis, we are interested in the extension of conventional SIMO-MLSE receivers to new architectures exploiting the potential second order non-circularity of co-channel interference (CCI), for the demodulation of rectilinear signals (BPSK, ASK), quasi-rectilinear (MSK, GMSK and OQAM) and quadrature amplitude modulation (QAM). The general architecture of the developed receivers is based on a pre-processing with a widely linear (WL) extension of the spatio-temporal matched filter, bringing the demodulation processing back to a scalar problem, a sampling at the symbol rate and then a decision block based on a modified version of the Viterbi algorithm. For the particular case of the quasi-rectilinear signals, a derotation processing is interposed between the sampler and the decision block. A work on equivalent discrete time modeling of SOI, interferers and background noise has been carried out in order to create simulation models as for the validation of the interpretable analytic SINR expressions, by the evaluation of the symbol error rates. In a second part, we are interested to the beamforming through complex Volterra structures of the third order. These structures allow us the exploitation of the non-circularity up to the sixth order as well as the non-gaussian nature of the SOI and/or the interferences. For passive listening applications, we have introduced a third-order Volterra MVDR beamformer using only a priori information of SOI steering vector and implemented by an equivalent GSC structure. We have studied its performance, in particular by interpretable closed-form expressions as functions of statistics of the interference, and by its speed of learning, thus proving its advantages with respect to the conventional linear and WL MVDR beamformers. For wireless communications applications, we have studied an MMSE version of this complex Volterra beamformer of the third order that takes into account of the non-circularity up to the sixth order as well as the non-gaussian nature of the SOI and interference. The last part of this thesis is devoted to the robustness of rectilinearity tests in the presence of frequency offset. These tests are important for adjusting the processing (linear or WL) as a function of the rectilinearity of the signals in order to guarantee the best performance/convergence rate ratio of algorithms
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Vandelle, Erika. "Exploration de solutions antennaires et de formation passive de faisceaux pour la récupération et le transfert d’énergie sans fil". Thesis, Université Grenoble Alpes (ComUE), 2019. http://www.theses.fr/2019GREAT060.
Testo completoAbstract (sommario):
La récupération d’énergie électromagnétique provenant de sources ambiantes ou intentionnelles, de fréquences allant de 100 MHz à 10 GHz, est apparue ces dernières années comme une solution prometteuse pour développer l’électronique autoalimentée. Cependant, les faibles densités de puissance, généralement plus faibles que 1 μW.cm-2, engendrent de faibles efficacités de redressement et de faibles sensibilités, et la diversité des signaux ambients (direction d’arrivée et polarisation inconnues et variant dans le temps) ne permet pas d’utiliser des antennes directives.Dans cette thèse, les techniques de combinaison de la puissance RF ou DC dans des systèmes de récupération d’énergie à multiples antennes, associées à des structures originales, sont étudiées pour faire face aux différents verrous technologiques. De plus, une nouvelle Figure-de-Mérite, décrivant la capacité d’un système à récupérer de l’énergie ambiante, est développée avec des termes de probabilités représentant la diversité fréquentielle, spatiale et de polarisation des signaux ambiants.La première partie de cette thèse se consacre à la conception d’antennes et de rectennas individuelles efficaces. Des prototypes peu chers et recyclables sont proposés sur un substrat papier grâce à une technique originale de réduction des pertes.Dans la deuxième partie de cette thèse, l’efficacité de conversion RF-DC est améliorée à travers la combinaison de la puissance RF avant le processus de redressement, sans pour autant réduire la couverture spatiale du système. Pour cela, une structure 3D multidirectionnelle de réseaux d’antennes associés à des réseaux interférométriques passifs, pour la formation de faisceaux, est conçue, afin d’obtenir un diagramme de rayonnement multidirectionnel à fort gain. Cette solution inspirée des systèmes de radar et impliquant des matrices de Butler, aboutit à une haute efficacité de conversion RF-DC ainsi qu’à une couverture spatiale optimale. Ainsi, une capacité à récupérer de l’énergie plus grande que celles de l’état-de-l’art est obtenue.La dernière partie de cette thèse propose de remédier à la limite en sensibilité de la combinaison de puissance RF, plus faible qu’avec une combinaison DC en série de la puissance, grâce à un système reconfigurable. Pour cela, des cellules unitaires de rectennas sont conçues afin de former un réseau interférométrique adaptable et extensible, qui offre la possibilité d’obtenir un système hautement efficace et sensible à la fois. Cette solution peut servir à la récupération d’énergie, à la localisation passive et autonome ou à des applications RFIDWireless energy harvesting (WEH) of ambient or intentional electromagnetic power sources of frequency ranging from 100 MHz to 10 GHz, has appeared as a promising solution to develop self-powered electronics in the past decades. However, the low power densities available, usually lower than 1 uW.cm-2, result in a limited RF-to-DC conversion efficiency and sensitivity of the energy harvesting system (rectenna) and the ambient signal diversities (unknown and time-varying direction of arrival, polarization) prohibit the use of directive antennas.In this thesis, the power combination techniques of Radio Frequency (RF) or Direct Current (DC) power in multi-antenna WEH systems, together with original structures, are investigated to address those challenges. Besides, a new Figure-of-Merit (harvesting capability) for rectennas operating in ambient scenarios is derived with probabilistic terms representing the frequency, polarization and spatial diversities of ambient signals.The first part of this thesis focuses on the design of efficient antenna and rectenna elements. Eco-responsible and low-cost prototypes are proposed by using a paper substrate along with an original strategy for the reduction of the losses.In the second part of this work, the rectification efficiency of a WEH system is enhanced through the combination of the RF power prior to the rectification process, without reduction of the spatial coverage. For this, a 3D multidirectional structure of scanning antenna arrays using passive beam-forming networks is designed to obtain a multidirectional high gain aggregate pattern. This radar-inspired solution involving Butler matrices results in a highly efficient RF-to-DC power conversion along with an optimal angular coverage, which leads to a harvesting capability higher than the state-of-the-art.The last part of this work addresses the limited sensitivity of the RF combination technique compared to that obtained with the series DC combination technique thanks to a reconfigurable system. To this end, modular rectenna unit cells are designed to form a scalable and adaptative interferometric beam-forming network, which offers the possibility to achieve a highly efficient and sensitive WEH system. This solution is suitable for low-power energy harvesting, autonomous passive tracking or RFID applications
Capitoli di libri sul tema "Passive Beamforming"
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Yu, Yikun, Peter G. M. Baltus e Arthur H. M. van Roermund. "A 60GHz Passive Phase Shifter". In Integrated 60GHz RF Beamforming in CMOS, 47–58. Dordrecht: Springer Netherlands, 2011. http://dx.doi.org/10.1007/978-94-007-0662-0_5.
Testo completo
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Li, MengLei, YueLin Xu, ShiRui Wang e YiQing Li. "Passive Detection Beamforming Based on Arc Array". In Advanced Intelligent Technologies for Information and Communication, 13–21. Singapore: Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-99-5203-8_2.
Testo completo
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Pusone, E. G., e L. J. Lloyd. "Passive Synthetic Aperture Sonar — An Analysis of the Beamforming Process". In Adaptive Methods in Underwater Acoustics, 731–39. Dordrecht: Springer Netherlands, 1985. http://dx.doi.org/10.1007/978-94-009-5361-1_61.
Testo completo
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He, Chen, Xie Xie, Yangrui Dong e Shun Zhang. "Joint Power Allocation and Passive Beamforming Design for IRS-Assisted Cell-free Networks". In Communications and Networking, 264–74. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-99200-2_21.
Testo completo
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Awad, Safa, Rui Wang e Ismael Soto. "Target Detection in ISAC System Equipped with IRS: A Joint Active and Passive Beamforming Approach". In Lecture Notes of the Institute for Computer Sciences, Social Informatics and Telecommunications Engineering, 66–80. Cham: Springer Nature Switzerland, 2024. http://dx.doi.org/10.1007/978-3-031-67162-3_5.
Testo completo
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Kallinich, Nina, Martin Thorwart e Wolfgang Rabbel. "Determination of the subsurface structure of the Chora Plain (Samos) by seismic noise analysis". In Advances in On- and Offshore Archaeological Prospection, 415–18. Kiel: Universitätsverlag Kiel | Kiel University Publishing, 2023. http://dx.doi.org/10.38072/978-3-928794-83-1/p84.
Testo completoAbstract (sommario):
Seismic noise was passively recorded with mini-arrays, allowing shear wave velocities of individual layers to be estimated. A statistical analysis by beamforming was performed. A 1D underground model of the Chora plain was derived. Three dominant structures were found: coastal barrier, siltated lagoon and the interior of the Chora plain.
Atti di convegni sul tema "Passive Beamforming"
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Huang, Jiansong, Wen-Bin Sun, Yanyun Gong, Lue Wang e Ling Wang. "Passive Beamforming for RIS-Assisted OTFS Systems". In 2024 IEEE/CIC International Conference on Communications in China (ICCC), 427–32. IEEE, 2024. http://dx.doi.org/10.1109/iccc62479.2024.10681906.
Testo completo
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Chêne, Thomas, e Ghaya Rekaya-Ben Othman. "Adaptive Bayesian Method for RIS Passive Beamforming". In 2024 19th International Symposium on Wireless Communication Systems (ISWCS), 1–6. IEEE, 2024. http://dx.doi.org/10.1109/iswcs61526.2024.10639111.
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Chen, Zhen, Zhenqiu Jian e Kai Fang. "Joint Power Allocation and Passive Beamforming for Distributed RIS Multiuser Networks". In 2024 9th International Conference on Signal and Image Processing (ICSIP), 126–31. IEEE, 2024. http://dx.doi.org/10.1109/icsip61881.2024.10671553.
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Wu, Sili, Shuyan Hu, Zaichuan Zhang e Xin Wang. "Active and Passive Beamforming for STAR-RIS Aided ISAC in IoT Networks". In 2024 16th International Conference on Wireless Communications and Signal Processing (WCSP), 1163–68. IEEE, 2024. https://doi.org/10.1109/wcsp62071.2024.10827223.
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Luo, Jintao, e Sixing Yin. "Intelligent Reflecting Surface Aided Wireless Communication Systems: Joint Location and Passive Beamforming Design". In 2024 IEEE 7th International Conference on Electronic Information and Communication Technology (ICEICT), 889–95. IEEE, 2024. http://dx.doi.org/10.1109/iceict61637.2024.10671014.
Testo completo
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Zhang, Jifa, Mingqian Liu, Jie Tang, Nan Zhao, Dusit Niyato e Xianbin Wang. "Joint Waveform and Passive Beamforming Design for IRS-Aided ISAC via Deep Unfolding". In 2024 16th International Conference on Wireless Communications and Signal Processing (WCSP), 734–39. IEEE, 2024. https://doi.org/10.1109/wcsp62071.2024.10827035.
Testo completo
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Barhen, Jacob, Travis Humble e Michael Traweek. "FFT-based sonar array beamforming without corner turning". In 2008 New Trends for Environmental Monitoring Using Passive Systems (PASSIVE 2008). IEEE, 2008. http://dx.doi.org/10.1109/passive.2008.4786980.
Testo completo
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Pawlukiewicz, Stanley, e Kathleen E. Wage. "Passive Coprime Split Aperture Beamforming". In OCEANS 2018 MTS/IEEE Charleston. IEEE, 2018. http://dx.doi.org/10.1109/oceans.2018.8604653.
Testo completo
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Yocom, Bryan A., T. W. Yudichak e Brian R. La Cour. "Passive beamforming enhancements in relation to active-passive data fusion". In 2008 42nd Asilomar Conference on Signals, Systems and Computers. IEEE, 2008. http://dx.doi.org/10.1109/acssc.2008.5074430.
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Tamminen, Aleksi, Samu-Ville Pälli, Juha Ala-Laurinaho, Arthur Aspelin, Akseli Oinaanoja e Zachary Taylor. "Holograms with neural-network backend for submillimeter-wave beamforming applications". In Passive and Active Millimeter-Wave Imaging XXIII, a cura di Duncan A. Robertson e David A. Wikner. SPIE, 2020. http://dx.doi.org/10.1117/12.2557754.
Testo completo