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742 results on '"Oliver, Miquel"'

51. On the Distributed Construction of a Collision-Free Schedule in Multi-Hop Packet Radio Networks

Author

Barcelo, Jaume, Bellalta, Boris, Cano, Cristina, Faridi, Azadeh, and Oliver, Miquel

Subjects
Computer Science - Networking and Internet Architecture
Abstract

This paper introduces a protocol that distributively constructs a collision-free schedule for multi-hop packet radio networks in the presence of hidden terminals. As a preliminary step, each wireless station computes the schedule length after gathering information about the number of flows in its neighbourhood. Then, a combination of deterministic and random backoffs are used to reach a collision-free schedule. A deterministic backoff is used after successful transmissions and a random backoff is used otherwise. It is explained that the short acknowledgement control packets can easily result in channel time fragmentation and, to avoid this, the use of link layer delayed acknowledgements is advocated and implemented. The performance results show that a collision-free protocol easily outperforms a collision-prone protocol such as Aloha. The time that is required for the network to converge to a collision-free schedule is assessed by means of simulation.

Published
2012

52. Hierarchical Range Sectoring and Bidirectional Link Quality Estimation for On-demand Collections in WSNs

Author

Valls, Víctor, Sánchez, José Luis, Cano, Cristina, Bellalta, Boris, and Oliver, Miquel

Subjects
Computer Science - Networking and Internet Architecture
Abstract

The paper presents two mechanisms for designing an on-demand, reliable and efficient collection protocol for Wireless Sensor Networks. The former is the Bidirectional Link Quality Estimation, which allows nodes to easily and quickly compute the quality of a link between a pair of nodes. The latter, Hierarchical Range Sectoring, organizes sensors in different sectors based on their location within the network. Based on this organization, nodes from each sector are coordinated to transmit in specific periods of time to reduce the hidden terminal problem. To evaluate these two mechanisms, a protocol called HBCP (Hierarchical-Based Collection Protocol), that implements both mechanisms, has been implemented in TinyOS 2.1, and evaluated in a testbed using TelosB motes. The results show that the HBCP protocol is able to achieve a very high reliability, especially in large networks and in scenarios with bottlenecks., Comment: 22 pages, 11 figures

Published
2012

53. On the Performance of Packet Aggregation in IEEE 802.11ac MU-MIMO WLANs

Author

Bellalta, Boris, Barcelo, Jaume, Staehle, Dirk, Vinel, Alexey, and Oliver, Miquel

Subjects
Computer Science - Networking and Internet Architecture
Abstract

Multi-user spatial multiplexing combined with packet aggregation can significantly increase the performance of Wireless Local Area Networks (WLANs). In this letter, we present and evaluate a simple technique to perform packet aggregation in IEEE 802.11ac MU-MIMO (Multi-user Multiple Input Multiple Output) WLANs. Results show that in non-saturation conditions both the number of active stations (STAs) and the queue size have a significant impact on the system performance. If the number of stations is excessively high, the heterogeneity of destinations in the packets contained in the queue makes it difficult to take full advantage of packet aggregation. This effect can be alleviated by increasing the queue size, which increases the chances to schedule a large number of packets at each transmission, hence improving the system throughput at the cost of a higher delay.

Published
2012

54. Performance Optimization of Multiple Interconnected Heterogeneous Sensor Networks via Collaborative Information Sharing

Author

Pal, Sougata, Oechsner, Simon, Bellalta, Boris, and Oliver, Miquel

Subjects
Computer Science - Networking and Internet Architecture
Abstract

Interconnecting multiple sensor networks is a relatively new research field which has emerged in the Wireless Sensor Network domain. Wireless Sensor Networks (WSNs) have typically been seen as logically separate, and few works have considered interconnection and interaction between them. Interconnecting multiple heterogeneous sensor networks therefore opens up a new field besides more traditional research on, e.g., routing, self organization, or MAC layer development. Up to now, some approaches have been proposed for interconnecting multiple sensor networks with goals like information sharing or monitoring multiple sensor networks. In this paper, we propose to utilize inter-WSN communication to enable Collaborative Performance Optimization, i.e., our approach aims to optimize the performance of individual WSNs by taking into account measured information from others. The parameters to be optimized are energy consumption on the one hand and sensing quality on the other.

Published
2012

55. Towards a Collision-Free WLAN: Dynamic Parameter Adjustment in CSMA/E2CA

Author

Barcelo, Jaume, Bellalta, Boris, Cano, Cristina, Sfairopoulou, Anna, Oliver, Miquel, and Verma, Kshitiz

Subjects
Computer Science - Networking and Internet Architecture
Abstract

Carrier Sense Multiple Access with Enhanced Collision Avoidance (CSMA/ECA) is a distributed MAC protocol that allows collision-free access to the medium in WLAN. The only difference between CSMA/ECA and the well-known CSMA/CA is that the former uses a deterministic backoff after successful transmissions. Collision-free operation is reached after a transient state during which some collisions may occur. This article shows that the duration of the transient state can be shortened by appropriately setting the contention parameters. Standard absorbing Markov Chain theory can be used to describe the behaviour of the system in the transient state and to predict the expected number of slots to reach the collision-free operation. The article also introduces CSMA/E2CA, in which a deterministic backoff is used two consecutive times after a successful transmission. CSMA/E2CA converges quicker to collision-free operation and delivers higher performance than CSMA/CA in harsh wireless scenarios with high frame error rates. To achieve collision-free operations when the number of contenders is large, it may be necessary to dynamically adjust the contention parameter. The last part of the article suggests an approach for such parameter adjustment which is validated by simulation results.

Published
2010

56. Supramolecular Assemblies in Mn(II) and Zn(II) Metal–Organic Compounds Involving Phenanthroline and Benzoate: Experimental and Theoretical Studies.

Author

Boro, Mridul, Banik, Subham, Gomila, Rosa M., Frontera, Antonio, Barcelo-Oliver, Miquel, and Bhattacharyya, Manjit K.

Subjects
ORGANOMETALLIC compounds, ATOMS in molecules theory, BENZOATES, PHENANTHROLINE, HYDROGEN bonding interactions, MOLECULES, DIMERS
Abstract

Two new Mn(II) and Zn(II) metal–organic compounds of 1,10-phenanthroline and methyl benzoates viz. [Mn(phen)2Cl2]2-ClBzH (1) and [Zn(4-MeBz)2(2-AmPy)2] (2) (where 4-MeBz = 4-methylbenzoate, 2-AmPy = 2-aminopyridine, phen = 1,10-phenanthroline, 2-ClBzH = 2-chlorobenzoic acid) were synthesized and characterized using elemental analysis, TGA, spectroscopic (FTIR, electronic) and single crystal X-ray diffraction techniques. The crystal structure analysis of the compounds revealed the presence of various non-covalent interactions, which provides stability to the crystal structures. The crystal structure analysis of compound 1 revealed the formation of a supramolecular dimer of 2-ClBzH enclathrate within the hexameric host cavity formed by the neighboring monomeric units. Compound 2 is a mononuclear compound of Zn(II) where flexible binding topologies of 4-CH3Bz are observed with the metal center. Moreover, various non-covalent interactions, such as lp(O)-π, lp(Cl)-π, C–H∙∙∙Cl, π-stacking interactions as well as N–H∙∙∙O, C–H∙∙∙O and C–H∙∙∙π hydrogen bonding interactions, are found to be involved in plateauing the molecular self-association of the compounds. The remarkable enclathration of the H-bonded 2-ClBzH dimer into a supramolecular cavity formed by two [Mn(phen)2Cl2] complexes were further studied theoretically using density functional theory (DFT) calculations, the non-covalent interaction (NCI) plot index and quantum theory of atoms in molecules (QTAIM) computational tools. Synergistic effects were also analyzed using molecular electrostatic potential (MEP) surface analysis. [ABSTRACT FROM AUTHOR]

Published
2024
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68. Josep Ferragut, un arquitecte modern

Author

Universitat Politècnica de Catalunya. Departament de Projectes Arquitectònics, Beuter Sánchez-Villanueva, Carolina, Linares de la Torre, Óscar, Gallego Urbano, Àlex, Ferrer Forés, Jaime Jose, Busquets Oliver, Miquel, Universitat Politècnica de Catalunya. Departament de Projectes Arquitectònics, Beuter Sánchez-Villanueva, Carolina, Linares de la Torre, Óscar, Gallego Urbano, Àlex, Ferrer Forés, Jaime Jose, and Busquets Oliver, Miquel

Abstract

Josep Ferragut Pou sintetitza un anhel modern que construeix a través de nombroses influències d’arquitectures i corrents contemporànies, creant un imaginari modern trencador amb les dinàmiques conservadores del context mallorquí. Com a vincle entre la tradició mediterrània i el llenguatge modern, consolida un llegat ple d’obres que s’entenen i interpreten a través de les influències exteriors dels grans mestres de l’arquitectura contemporània, sent la comparació d’aquestes la lògica d’aquest treball. Amb les influències i confluències que s’analitzaran es configurarà una col·lecció de plànols i documents que permetran al lector construir un imaginari de l’origen, sistema i les pautes de l’arquitectura de Josep Ferragut, tractant de divulgar una arquitectura honesta i singular d’un arquitecte poc reconegut a fora de l’illa de Mallorca., Josep Ferragut Pou synthesizes a modern longing that he builds through numerous architectural influences and contemporary trends that create a modern imaginary which breaks the conservative dynamics of the Mallorcan context. As a link between the Mediterranean tradition and the modern language, he consolidates a legacy full of projects that are understood and interpreted through the external influences of the great masters of contemporary architecture, the comparison of these being the logic of this thesis. With the influences and confluences that will be analyzed, a collection of plans and documents will be set up, allowing the reader to build an imaginary of the origin, system and guidelines of Josep Ferragut’s architecture and will try to spread an honest and singular architecture held by an architect little recognized outside the island of Mallorca.

Published
2023

69. A Queueing Model for SDMA Downlink Transmissions

Author

Liao, Ruizhi, Bellalta, Boris, Oliver, Miquel, Garcia, Núria, Hutchison, David, editor, Kanade, Takeo, editor, Kittler, Josef, editor, Kleinberg, Jon M., editor, Mattern, Friedemann, editor, Mitchell, John C., editor, Naor, Moni, editor, Nierstrasz, Oscar, editor, Pandu Rangan, C., editor, Steffen, Bernhard, editor, Sudan, Madhu, editor, Terzopoulos, Demetri, editor, Tygar, Doug, editor, Vardi, Moshe Y., editor, Weikum, Gerhard, editor, Vinel, Alexey, editor, Bellalta, Boris, editor, Sacchi, Claudio, editor, Lyakhov, Andrey, editor, Telek, Miklós, editor, and Oliver, Miquel, editor

Published
2010
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70. Dynamic Parameter Adjustment in CSMA/ECA

Author

Barcelo, Jaume, Bellalta, Boris, Cano, Cristina, Sfairopoulou, Anna, Oliver, Miquel, Hutchison, David, editor, Kanade, Takeo, editor, Kittler, Josef, editor, Kleinberg, Jon M., editor, Mattern, Friedemann, editor, Mitchell, John C., editor, Naor, Moni, editor, Nierstrasz, Oscar, editor, Pandu Rangan, C., editor, Steffen, Bernhard, editor, Sudan, Madhu, editor, Terzopoulos, Demetri, editor, Tygar, Doug, editor, Vardi, Moshe Y., editor, Weikum, Gerhard, editor, Vinel, Alexey, editor, Bellalta, Boris, editor, Sacchi, Claudio, editor, Lyakhov, Andrey, editor, Telek, Miklós, editor, and Oliver, Miquel, editor

Published
2010
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71. Mercury: Revealing Hidden Interconnections Between Access ISPs and Content Providers

Author

Palacin, Manuel, Bikfalvi, Alex, Oliver, Miquel, Hutchison, David, Series editor, Kanade, Takeo, Series editor, Kittler, Josef, Series editor, Kleinberg, Jon M., Series editor, Mattern, Friedemann, Series editor, Mitchell, John C., Series editor, Naor, Moni, Series editor, Pandu Rangan, C., Series editor, Steffen, Bernhard, Series editor, Terzopoulos, Demetri, Series editor, Tygar, Doug, Series editor, Weikum, Gerhard, Series editor, and Kermarrec, Yvon, editor

Published
2014
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81. DISON: A Self-organizing Network Management Framework for Wireless Sensor Networks

Author

Cao Minh, Trang, Bellalta, Boris, Oliver, Miquel, Akan, Ozgur, Series editor, Bellavista, Paolo, Series editor, Cao, Jiannong, Series editor, Dressler, Falko, Series editor, Ferrari, Domenico, Series editor, Gerla, Mario, Series editor, Kobayashi, Hisashi, Series editor, Palazzo, Sergio, Series editor, Sahni, Sartaj, Series editor, Shen, Xuemin (Sherman), Series editor, Stan, Mircea, Series editor, Xiaohua, Jia, Series editor, Zomaya, Albert, Series editor, Coulson, Geoffrey, Series editor, Zheng, Jun, editor, Mitton, Nathalie, editor, Li, Jun, editor, and Lorenz, Pascal, editor

Published
2013
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82. White Spaces in UHF Band: Catalonia Case Study and Impact of the Digital Dividend

Author

Domingo, Albert, Bellalta, Boris, Oliver, Miquel, Hutchison, David, Series editor, Kanade, Takeo, Series editor, Kittler, Josef, Series editor, Kleinberg, Jon M., Series editor, Mattern, Friedemann, Series editor, Mitchell, John C., Series editor, Naor, Moni, Series editor, Nierstrasz, Oscar, Series editor, Pandu Rangan, C., Series editor, Steffen, Bernhard, Series editor, Sudan, Madhu, Series editor, Terzopoulos, Demetri, Series editor, Tygar, Doug, Series editor, Vardi, Moshe Y., Series editor, Weikum, Gerhard, Series editor, Szabó, Róbert, editor, and Vidács, Attila, editor

Published
2012
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83. Receiver-Initiated vs. Short-Preamble Burst MAC Approaches for Multi-channel Wireless Sensor Networks

Author

Cano, Cristina, Bellalta, Boris, Oliver, Miquel, Hutchison, David, Series editor, Kanade, Takeo, Series editor, Kittler, Josef, Series editor, Kleinberg, Jon M., Series editor, Mattern, Friedemann, Series editor, Mitchell, John C., Series editor, Naor, Moni, Series editor, Nierstrasz, Oscar, Series editor, Pandu Rangan, C., Series editor, Steffen, Bernhard, Series editor, Sudan, Madhu, Series editor, Terzopoulos, Demetri, Series editor, Tygar, Doug, Series editor, Vardi, Moshe Y., Series editor, Weikum, Gerhard, Series editor, Szabó, Róbert, editor, and Vidács, Attila, editor

Published
2012
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84. Buffer Sizing in TxSDMA Systems

Author

Bellalta, Boris, Daza, Vanesa, Barcelo, Jaume, Oliver, Miquel, Hutchison, David, Series editor, Kanade, Takeo, Series editor, Kittler, Josef, Series editor, Kleinberg, Jon M., Series editor, Mattern, Friedemann, Series editor, Mitchell, John C., Series editor, Naor, Moni, Series editor, Nierstrasz, Oscar, Series editor, Pandu Rangan, C., Series editor, Steffen, Bernhard, Series editor, Sudan, Madhu, Series editor, Terzopoulos, Demetri, Series editor, Tygar, Doug, Series editor, Vardi, Moshe Y., Series editor, Weikum, Gerhard, Series editor, Sacchi, Claudio, editor, Bellalta, Boris, editor, Vinel, Alexey, editor, Schlegel, Christian, editor, Granelli, Fabrizio, editor, and Zhang, Yan, editor

Published
2011
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85. Collision-Free Operation in Wireless Ad-Hoc Networks

Author

Barcelo, Jaume, Bellalta, Boris, Oliver, Miquel, Banchs, Albert, Hutchison, David, Series editor, Kanade, Takeo, Series editor, Kittler, Josef, Series editor, Kleinberg, Jon M., Series editor, Mattern, Friedemann, Series editor, Mitchell, John C., Series editor, Naor, Moni, Series editor, Nierstrasz, Oscar, Series editor, Pandu Rangan, C., Series editor, Steffen, Bernhard, Series editor, Sudan, Madhu, Series editor, Terzopoulos, Demetri, Series editor, Tygar, Doug, Series editor, Vardi, Moshe Y., Series editor, Weikum, Gerhard, Series editor, Sacchi, Claudio, editor, Bellalta, Boris, editor, Vinel, Alexey, editor, Schlegel, Christian, editor, Granelli, Fabrizio, editor, and Zhang, Yan, editor

Published
2011
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93. Adapting a Captive Portal to Enable SMS-Based Micropayment for Wireless Internet Access

Author

Barceló, Jaume, Oliver, Miquel, Infante, Jorge, Hutchison, David, editor, Kanade, Takeo, editor, Kittler, Josef, editor, Kleinberg, Jon M., editor, Mattern, Friedemann, editor, Mitchell, John C., editor, Naor, Moni, editor, Nierstrasz, Oscar, editor, Pandu Rangan, C., editor, Steffen, Bernhard, editor, Sudan, Madhu, editor, Terzopoulos, Demetri, editor, Tygar, Dough, editor, Vardi, Moshe Y., editor, Weikum, Gerhard, editor, Stiller, Burkhard, editor, Reichl, Peter, editor, and Tuffin, Bruno, editor

Published
2006
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94. A BEB-Based Admission Control for VoIP Calls in WLAN with Coexisting Elastic TCP Flows

Author

Bellalta, Boris, Meo, Michela, Oliver, Miquel, Hutchison, David, Series editor, Kanade, Takeo, Series editor, Kittler, Josef, Series editor, Kleinberg, Jon M., Series editor, Mattern, Friedemann, Series editor, Mitchell, John C., Series editor, Naor, Moni, Series editor, Nierstrasz, Oscar, Series editor, Pandu Rangan, C., Series editor, Steffen, Bernhard, Series editor, Sudan, Madhu, Series editor, Terzopoulos, Demetri, Series editor, Tygar, Dough, Series editor, Vardi, Moshe Y., Series editor, Weikum, Gerhard, Series editor, Koucheryavy, Yevgeni, editor, Harju, Jarmo, editor, and Iversen, Villy B., editor

Published
2006
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95. Comprehensive Analytical Models to Evaluate the TCP Performance in 802.11 WLANs

Author

Bellalta, Boris, Meo, Michela, Oliver, Miquel, Hutchison, David, editor, Kanade, Takeo, editor, Kittler, Josef, editor, Kleinberg, Jon M., editor, Mattern, Friedemann, editor, Mitchell, John C., editor, Naor, Moni, editor, Nierstrasz, Oscar, editor, Pandu Rangan, C., editor, Steffen, Bernhard, editor, Sudan, Madhu, editor, Terzopoulos, Demetri, editor, Tygar, Dough, editor, Vardi, Moshe Y., editor, Weikum, Gerhard, editor, Braun, Torsten, editor, Carle, Georg, editor, Fahmy, Sonia, editor, and Koucheryavy, Yevgeni, editor

Published
2006
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98. Oxalic Acid, a Versatile Coformer for Multicomponent Forms with 9-Ethyladenine

Author

Ministerio de Ciencia e Innovación (España), Generalitat de Catalunya, Universidad de Las Islas Baleares, Ministerio de Ciencia, Innovación y Universidades (España), Benito, Mónica, Barceló Oliver, Miquel, Frontera, Antonio, Molins, Elies, Ministerio de Ciencia e Innovación (España), Generalitat de Catalunya, Universidad de Las Islas Baleares, Ministerio de Ciencia, Innovación y Universidades (España), Benito, Mónica, Barceló Oliver, Miquel, Frontera, Antonio, and Molins, Elies

Abstract

Six new multicomponent solids of 9-ethyladenine and oxalic acid have been detected and characterized. The salt screening has been performed by mechanochemical and solvent crystallization processes. Single crystals of the anhydrous salts in 1:1 and 2:1 nucleobase:coformer molar ratio were obtained by solution crystallization and elucidated by single-crystal X-ray analysis. The supramolecular interactions observed in these solids have been studied using density functional theory (DFT) calculations and characterized by the quantum theory of “atoms in molecules” (QTAIM) and the noncovalent interaction plot (NCIPlot) index methods. The energies of the H-bonding networks observed in the solid state of the anhydrous salts in 1:1 and 2:1 nucleobase:coformer are reported, disclosing the strong nature of the charge assisted NH···O hydrogen bonds and also the relative importance of ancillary C–H··O H-bonds.

Published
2022

99. Indicators for the Evaluation of Environmental Education, Interpretation and Information in Protected Areas

Author

Sureda, Jaume, Oliver, Miquel F., and Castells, Margalida

Abstract

By petition of the regional government of the Balearic Islands (Spain), the authors of this article evaluated activities of environmental education, interpretation, and information carried out in the most important protected areas of these islands. The following is a presentation of the model of the evaluation that was developed. Based on the results of this evaluation, a set of indicators applicable to the analysis of the communicative function in protected areas is proposed. (Contains 2 figures, 1 table and 1 footnote.)

Published
2004
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