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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
61

Uma proposta metodológica para a previsão do Throughput durante a inicialização de redes Profinet através de redes neurais artificiais / A proposal of a methodology to preview Throughput in Profinet network using Artificial Neural Networks

Guilherme Serpa Sestito 28 November 2014 (has links)
Este trabalho propõe o desenvolvimento de uma metodologia para o cálculo do volume de tráfego durante o período de inicialização de uma rede Profinet. O tráfego de dados é um dos indicadores de desempenho criados para garantir a qualidade dos protocolos baseados em Real Time Ethernet (RTE). Neste contexto, buscou-se na literatura uma forma de classificar o tráfego de acordo com a sua magnitude e mensurar seu efeito na comunicação. Dados provenientes de redes criadas em laboratório foram coletados e aplicados a uma Rede Neural Artificial visando generalizar o conhecimento adquirido. O uso dado a RNA foi de estimação da função de interesse. Os resultados obtidos após o processamento dos dados reais são considerados satisfatórios e condizentes às expectativas dessa dissertação, já que se buscou, por razões inerentes ao problema estudado, um erro relativo inferior 3%. Conclui-se que a metodologia apresentada é factível e aplicável ao meio industrial, podendo ser parte de uma ferramenta mais completa, como os analisadores de redes Profinet. / This paper suggests the development of a methodology to calculate the traffic volume during the starting period of a Profinet network. The data traffic is one of the development indicators created to guarantee the protocols quality based on Real Time Ethernet (RTE). In this context, a way of classifying the traffic according to its magnitude and of measuring its effect in the communication was searched in the literature. Data deriving from networks created in laboratory were collected and applied into an Artificial Neural Network aiming to generalize the acquired knowledge. The ANN was used to estimate the function of interest. The results obtained after the real data processing are considered satisfactory and suitable to the expectations of this dissertation where the relative error inferior to 3%, for reasons intrinsic to the studied problem, was searched. It is concluded that the methodology presented is feasible and applicable in the industrial field, where it can be part of a more complete tool, as the Profinet network analyzers.
62

Performance Limits of Communication with Energy Harvesting

Znaidi, Mohamed Ridha 04 1900 (has links)
In energy harvesting communications, the transmitters have to adapt transmission to the availability of energy harvested during communication. The performance of the transmission depends on the channel conditions which vary randomly due to mobility and environmental changes. During this work, we consider the problem of power allocation taking into account the energy arrivals over time and the quality of channel state information (CSI) available at the transmitter, in order to maximize the throughput. Differently from previous work, the CSI at the transmitter is not perfect and may include estimation errors. We solve this problem with respect to the energy harvesting constraints. Assuming a perfect knowledge of the CSI at the receiver, we determine the optimal power policy for different models of the energy arrival process (offline and online model). Indeed, we obtain the power allocation scheme when the transmitter has either perfect CSI or no CSI. We also investigate of utmost interest the case of fading channels with imperfect CSI. Moreover, a study of the asymptotic behavior of the communication system is proposed. Specifically, we analyze of the average throughput in a system where the average recharge rate goes asymptotically to zero and when it is very high.
63

HIGH-THROUGHPUT ORGANIC REACTION SCREENING USING DESORPTION ELECTROSPRAY IONIZATION MASS SPECTROMETRY

David L Logsdon (8086205) 06 December 2019 (has links)
This dissertation describes the development of a system for the automated, high-throughput screening of organic reactions. This system utilizes a liquid handling robot for reaction mixture preparation combined with desorption electrospray ionization mass spectrometry (DESI-MS) for reaction mixture analysis. With an analysis speed of ~1 second per reaction mixture, this system is capable of screening thousands of reactions per hour. Reaction mixtures are prepared in 384-well microtiter plates using a liquid handling robot. A sample of each reaction mixture (50 nL) is then transferred to a PTFE coated, glass slide using a pin tool. By offsetting the placement of the pin tool during each transfer, up to 6,144 unique reaction mixtures can be placed on each slide. The slide is then transferred to the DESI stage by a robotic arm, and the DESI-MS analysis begins, taking as little as 7 minutes for 384 reaction mixtures. We utilize a scheduling software to control each component of the system, which automates the entire process from reaction mixture preparation to DESI-MS analysis. In order to efficiently analyze and visualize the extremely large data sets generated by the system, we developed a custom software suite to automatically process each data set. We have used this system to screen several classes of industrially relevant reactions including Suzuki coupling, nucleophilic aromatic substitution, reductive amination, and Sonogashira coupling. We have validated both positive and negative results from the system using flow chemistry, and we have observed excellent agreement between the two methodologies. By being capable of screening thousands of reactions per hour, requiring only microliter quantities of reaction mixtures, and consuming less than a milliliter of solvent during the DESI-MS analysis, this system significantly reduces the time and costs associated with organic reaction screening.
64

Increasing the Throughput of a Node.js Application : Running on the Heroku Cloud App Platform

Andersson, Niklas, Chernov, Aleksandr January 2016 (has links)
The purpose of this thesis was to investigate whether utilization of the Node.js Cluster module within a web application in an environment with limited resources (the Heroku Cloud App Platform) could lead to an increase in throughput of the application and, in the case of an increase, how substantial it was. This has been done by load testing an example application when utilizing the module and without utilizing it. In both scenarios, the traffic sent in to the application varied from 10 requests/second to 100 requests/second. For the tests conducted on the application utilizing the module the number of worker process used within the application varied between 1 and 16. Furthermore, the tests were first conducted in a local environment in order to establish any increases in throughput in a stable environment, and, in case there were notable differences in throughput of the application, the same tests were conducted on the Heroku Cloud App Platform. Each test was also aimed towards testing one of two different types of tasks performed by the application: I/O or CPU bound. From the test results, it could be derived that utilization of the Cluster module did not lead to any increases in throughput when the application was doing I/O bound tasks in neither of the environments. However, when doing CPU bound tasks, it led to a ≥20% increase when the traffic sent to the application in the local environment was 10 requests/second or higher. The same increase could be seen when the traffic sent to the application was 50 requests/second or higher in the Heroku environment. The conclusion was, thus, that utilization of the module would be useful for the company (that this thesis took place at) in case an application installed on Heroku was exposed to higher traffic. / Syftet med detta examensarbete var att undersöka om huruvida nyttjande av Node.jsmodulen Cluster i wen webbapplikation i en miljö med begränsade resurser (Heroku cloud appplattformen) skulle kunna leda till en ökning i throughput hos applikationen, och om det skedde en ökning – hur stor var då denna? Detta har gjorts genom att belastningstesta en exempelapplikation nyttjande modulen och utan den. I båda scenarier varierade trafiken som skickades till applikationen mellan 10 och 100 requests/sekund. För testerna utförda i applikationen som nyttjade modulen varierade antalet workerprocesser mellan 1 och16. Vidare utfördes testerna i den lokala miljön med målet att slå fast möjlig throughputökning i en stabil miljö först, och om det fanns några märkbara skillnaden i throughput hos applikationen skulle samma tester även utföras på Heroku app cloudplattformen. Varje test strävade också för att testa en av två olika typer av arbetsuppgifter utförda av applikationen: I/Oeller CPUbundna. Från testresultatet kunde det fastslås att: Clustermodulen ledde inte till några ökningar vad gällde throughput när applikationen gjorde I/Obundna arbetsuppgifter i någon av miljöerna. När applikationen däremot gjorde CPUbundna arbetsuppgifter ledde det till en ökning på ≥20% när trafiken var 10 requests/sekund eller högre. Samma ökning kunde ses först när trafiken kommer över 50 requests/sekund eller högre i Herokumiljön. Slutsatsen var därmed att användande av modulen skulle vara användbart för företaget som arbetet uträttades hos om en applikation som låg installerad på Heroku utsattes för vad som ansågs vara högre trafik.
65

Propriétés optiques, organisation moléculaire et dynamique des interfaces de microgouttelettes par un dispositif de détection optofluidique utra-sensible à large bande spectrale. / Optical Properties, Molecular Organization and Dynamics of Droplets Interfaces using a highly sensitive broadband optofluidic detection.

Hayat, Zain 18 December 2018 (has links)
La microfluidique diphasique permet la production et la manipulation de millions de gouttelettes hautement monodisperses, chacune d'entre elles peut servir de microréacteur indépendant. Cette technologie offre de grandes perspectives dans de nombreux domaines scientifiques et industriels (principalement en biotechnologie). Les gouttelettes peuvent être produites, analysées et manipulées à très haut débit grâce notamment à des méthodes optiques. De nombreuses études ont été menées pour améliorer cette technologie et ses applications mais une compréhension approfondie des processus dynamiques complexes se produisant à l'interface des gouttelettes et du fluide porteur (huile) n'est toujours pas bien comprise. Au cours de cette thèse, nous nous sommes intéressés au développement d’une nouvelle approche optofluidique permettant une meilleure analyse de la dynamique et l'organisation moléculaire aux interfaces des gouttelettes dans l’écoulement microfluidique.Notre première étude porte sur la conception et l'utilisation de surfactants photosensibles permettant de stabiliser les gouttelettes et d’induire ensuite leur fusion contrôlée à l'aide d’un laser UV pulsé. La lumière offrant une grande flexibilité, une accordabilité (longueur d’onde et intensité) et une haute résolution spatio-temporelle. Deux approches ont été développées : l’une basée sur la photolyse de molécules photolabiles (processus irréversible) et l’autre basée sur la photo-isomérisation de dérivées d'azobenzène (processus réversible). Le succès de ces deux approches n’était pas évident, car l’irradiation de l’interface à l’échelle microscopique induit des modifications au niveau de la tension interfaciale mais aussi au niveau des processus de diffusion et d’absorption des molécules tensio-actives à l’interface, chacune de ces étapes ajoute une échelle de temps et une distance caractéristique différente. Nos résultats ont permis de déterminer le coefficient de diffusion des surfactants dans la région de l’interface, ainsi que le véritable mécanisme de fusion des gouttes par photo-isomérisation.La deuxième étude porte sur la détection et l'analyse en temps réel des propriétés optiques de l’interface et ce afin de mieux comprendre sa construction, sa dynamique et l'organisation moléculaire dans l’écoulement hydrodynamique. Nous avons pour cela mis au point un système original de détection hautement sensible à large bande, utilisant un réflecteur parabolique ne nécessitant pas l’utilisation de filtres dichroïques. Nous obtenons ainsi une détection en temps réel ultra-sensible de la photoluminescence des gouttelettes sur une large plage spectrale. Nous avons mis en évidence pour la première fois l’apparition d’une émission anti-stokes, thermiquement activée (hot band emission). Celle-ci est principalement localisée au niveau de l’interface. Notre dispositif pourrait constituer un nouvel outil puissant d’analyse permettant de détecter et d’étudier les interfaces liquides avec une très grande résolution spatiale, temporelle et spectrale sans recourir à des techniques complexes d’imagerie et de microscopie optique. Nous montrons par exemple que, contrairement à la microscopie optique, l’émission anti-stokes mise en évidence permet de détecter la formation de vésicules (émulsion double) en temps réel et à très haut débit.Lors de la dernière étude, nous nous intéressons à la diffusion de colorants à travers des bicouches biomimétiques dans des systèmes microfluidiques. Deux approches ont été abordées, celle des bicouches à l’interface de microgouttes (Droplet Interface Bilayer) et celle des émulsions doubles (eau/huile/eau). Nos résultats préliminaires montrent que de tels systèmes constituent de bons modèles pour l’étude du transport de molécules et de médicaments à travers des membranes biologiques. / Droplet microfluidics offers tremendous applications and prospects in many scientific and industrial fields (mainly in biotechnology). The technology enables for the fabrication and manipulation of millions of highly monodisperse microdroplets, each of which may be regarded as an independent micro-reactor. Droplets may be produced, monitored, and manipulated at kHz rates, using mainly optical (optofluidics) methods. Numerous studies have been conducted to improve the technology but a thorough understanding of the complex fundamental dynamical processes occurring at the droplets interface are still not well understood. During this PhD work, we focused on the development of new optofluidics approaches for a better understanding of the dynamics and the molecular organization at the droplets interface during droplets production and droplets transport in microfluidic channels and chambers (traps).Our first study concerned the design and use of a droplet-stabilizing photoactive surfactant for a controlled merging of droplets using a ps UV-laser. This is particularly attractive approach since light provides flexibility, wavelength/intensity tunability and high temporal/spatial resolutions. We investigated two different methods: photolysis of photolabile molecules (irreversible process) and photo-isomerization of azobenzene derived molecules (reversible process). The success of approach was far from trivial, since illumination at the microscale induces changes not only in the dynamics of the interfacial tension but triggers also changes in diffusion and absorption of surfactant molecules at the droplets interface, each partial step adding a typical time and length-scale. Analysis of the measured merging time (found at the ms time scale) allowed for the determination of the diffusion coefficient of surfactant molecules around the droplet interface. Another important result was the first experimental demonstration of the mechanism of the light-driven merging process using photo-isomerization. It was found to rely on a subtle opto-mechanical process induced by the switching between trans and cis isomers of azobenzene surfactant molecules under illumination.In our second study, we focused on the real-time detection and analysis of the optical properties of dyes at the droplets interfaces, in order to better understand the building, the dynamics and the molecular organization of the droplet interface in the flow. For this aim, we developed an original broadband highly sensitive detection system, using an off-axis full VIS spectrum - collection, reflection and detection scheme. Our setup enables to achieve a real-time detection of droplets photo-luminescence over a large spectral range and at the ms timescale and to show for the first time the occurring of a thermally activated hot band anti-stokes shift emission. The later was found to localize mainly at the droplets interfaces. Based on this original result, we propose that our optofluidic system may serve as a new analysis tool to detect and study soft interfaces without the aid of optical imaging/recording techniques. The observed hot band anti-stokes shift is shown to be suitable for instance to detect and discriminate between flowing droplets and vesicles (or double emulsions) in a real-time and high throughput detection mode.In the last study, we were particularly interested in the study of mass transport and diffusion of dyes across biomimetic bilayers systems. Two major approaches were addressed, the droplet-interface-bilayer (DIB) and solvent evaporated water/oil/water double emulsions. Both techniques required rigorous design and micro-fabrication characterization. Preliminary results show that such systems may lead to the development of smart applications in soft-bio-mimetic membrane’s design, mass transport and drug carriers studies.
66

Jämförelse av OPS, MQTT och DDS med avseende på fördröjningstid och throughput / Comparison of OPS, MQTT and DDS with regards to latency and throughput

Nilsson, Kasper, Bergman, Alicia January 2023 (has links)
In this study a comparison of the publish-subscribe communication protocols OPS, MQTT and DDS were conducted. The implementation used for DDS was fastDDS and the client library Paho Eclipse MQTT C++ was used for MQTT with the broker implementation Eclipse Mosquitto. The goal was to see which out of these protocols performs best in a peer-to-peer communication scenario when it comes to latency and throughput with varying payload size. Two experiments were carried out. The first experiment measures the round-trip-time of a message and is realized by a ping-pong application. The latency was then calculated by taking half of the round-trip-time. The second experiment was publishing messages from one client and being retrieved by another and counting the amount of messages being retrieved in one second. To get bytes per second the payload size was multiplied by the amount of messages retrieved by the subscriber. The result of the first experiment showed that OPS with the underlying transport protocol TCP had the most favorable result. For the second experiment OPS with UDP as the transport protocol had the highest throughput in most cases however for the highest payload used in the experiment fastDDS with UDP had the highest throughput. However, the results gave substantial differences between the protocols in regards to throughput which indicate that the configuration might not be optimal for a fair comparison. Further research of this is recommended before making a final conclusion in regards to the overall results. / I denna studie genomfördes en jämförelse av kommunikationsprotokollen OPS, MQTT och DDS. Implementeringen som användes för DDS var fastDDS och klientbiblioteket Paho Eclipse MQTT C++ användes för MQTT med Eclipse Mosquitto som broker. Målet var att se vilket av dessa protokoll som fungerar bäst i ett peer-to-peer-kommunikationsscenario när det gäller fördröjningstid och throughput med varierande payloadstorlek. Två experiment utfördes. Det första experimentet mäter round-trip-time för ett meddelande och realiseras av en ping-pong-applikation. Fördröjningstiden beräknades sedan genom att ta hälften av round-trip-time. Det andra experimentet var att publicera meddelanden från en klient och mottas av en annan och räkna mängden meddelanden som mottas på en sekund. För att få byte per sekund multiplicerades payload storleken med mängden meddelanden som togs emot av prenumeranten. Resultatet av det första experimentet visade att OPS med det underliggande transportprotokollet TCP hade det mest gynnsamma resultatet. För det andra experimentet hade OPS med UDP som transportprotokoll den högsta throughput i de flesta fall, men för den största payloadstorleken som användes i experimentet hade fastDDS med UDP den högsta. Resultaten gav dock betydande skillnader mellan protokollen när det gäller throughput som indikerar att konfigurationen kanske inte är optimal för en rättvis jämförelse. Ytterligare forskning om detta rekommenderas för att utreda orsaken till dessa skillnader och därefter kunna skapa konfigurationer som ger rättvisa förutsättningar för en optimal jämförelse.
67

High-throughput experiment platform development for machine learning on chemical reactivity

Fraser, Douglas Gordon 16 June 2022 (has links)
High-throughput experimentation (HTE) is a form of accelerated testing which allows for many hundreds or thousands of experiments to be conducted in parallel or in rapid sequence. Recent advances in chemical reaction miniaturization have enabled HTE application toward chemical reaction exploration, and the resultant datasets present exciting opportunities for the incorporation of machine learning (ML) with organic chemistry to expedite reaction optimization and discovery. Disclosed herein is a modular HTE chemistry reaction platform with rapid and inexpensive data acquisition capabilities for training ML algorithms on organic chemistry. Comprising almost entirely off-the-shelf components and algorithms which will be made open-source, this platform facilitates data democratization through distributed generation. Underpinning this workflow is an innovative titration-based analysis method for semi-automated and quantitative conversion data acquisition at a rate of under fifteen seconds per sample. Requisite to this platform’s success are solutions to solid and liquid reagent distribution, reaction incubation, and fast, quantitative reaction analysis which is demonstrated in a proof-of-concept screening of the SNAr reaction toward the synthesis of proteolysis targeting chimera (PROTACs). It is hoped this platform lowers the barrier for entry to HTE for chemists through its modularity, approachability, and low operating costs. / 2024-06-16T00:00:00Z
68

High Throughput Screening of Nanoparticle Flotation Collectors

Abarca, Carla January 2017 (has links)
Carla Abarca Ph.D. Thesis / The selective separation of valuable minerals by froth flotation is a critical unit operation in mineral processing. Froth flotation is based on the ability of chemical reagents, called collectors, to selectively lower the surface energy of valuable mineral particles, facilitating attachment of the modified mineral particles to air bubbles in the flotation cell. The mineral laden bubbles rise to the surface forming a froth phase that can be isolated. Novel cationic polystyrene nanoparticle collectors have been developed recently to be used as effective flotation collectors, aiming to recover challenging nickel sulfide ores that respond poorly to conventional molecular flotation collectors. However, optimizing nanoparticle flotation collectors is a challenge. An effective nanoparticle collector candidate should meet three requirements: (1) it should be colloidally stable in the flotation media; (2) it should be hydrophobic enough to change the mineral surface and induce an air bubble-mineral particle attachment; and (3) specifically and strongly bind to metal-rich minerals. Producing nanoparticles that are simultaneously colloidally stable and sufficiently hydrophobic presents a problematic task. Thus, a delicate balance of nanoparticle properties is required for commercially viable nanoparticle collectors. This thesis presents a promising approach for discovering and characterizing novel nanoparticle collectors by using high throughput screening techniques. Developed was a workflow for fast fabrication and testing of nanoparticle candidates, including: (1) parallel production of large nanoparticle libraries covering a range of surface chemistries, (2) a high throughput colloidal stability assay to determine whether a nanoparticle type is stable in flotation conditions; (3) an automated contact angle assay to reject nanoparticles that are not hydrophobic enough to induce efficient bubble-particle attachment, and; (4) a laboratory flotation test in sodium carbonate (pH~10) with the best nanoparticle candidates. The automated colloidal stability assay was based on the optical characterization of diluted nanoparticle dispersions in multiwell plates, yielding critical coagulation concentrations (CCCs) of sodium carbonate. To pass this screening test, the CCC of candidate nanoparticles must be greater than the effective carbonate concentration in commercial flotation cells. Since the nanoparticle size affects the intrinsic light scattering properties of the nanoparticles, two routes were developed. The colloid stability assay was suitable for nanoparticles ranging between 50 nm and 500 nm, since nanoparticle size. The automated contact angle assay used a miniature 16-well plate format where flat glass slides were exposed to 200 μL nanoparticle dispersions. The cationic nanoparticles formed a saturated adsorbed monolayer on the glass, and after rinsing and drying, the water contact angle was automatically measured. Effective nanoparticle candidates had contact angles greater than 50 degrees, a criterion developed with model experiments. During the development of the automated workflow platform, a series of nanoparticles with methyl-ended PEG-methacrylate monomers were prepared. Although the PEG chains greatly enhanced colloidal stability, the particles were too hydrophilic to be effective collectors. Interestingly, nanoparticles with long PEG chains acted as froth modifiers, giving wetter and more robust foams as well as increased entrainment of materials that did not adhere to bubbles. Conventional laboratory scale latex synthesis methodologies are far too inefficient to generate large library of candidate nanoparticles. Instead, we started with a few parent nanoparticle types and then used Click chemistry to generate a large range of surface chemistries. Specifically copper-mediated azide alkyne cycloaddition reaction was used to functionalize the surface of azide nanoparticles with different chemical groups, ranging from hydrophilic amine-terminated PEG chains, to hydrophobic hexane-terminated materials. The Click library exhibited an extensive range of critical coagulation concentrations and contact angle values. For example, for a given parent azide nanoparticle, the contact angles ranged from 62 to 101 degrees, depending upon the density and type of click reagent. A novel paper chromatographic method was developed for the quantitative determination surface azide. This assay was critical for determining the surface density of functional groups from the click reactions. Overall, high throughput screening techniques were designed and applied to the development of nanoparticle collectors for froth flotation. Automated screening assays of critical coagulation concentration and contact angle proved to be effective in obtaining flotation domain maps, and finding the most promising nanoparticle collectors for froth flotation. I believe the work in this thesis is one of the first reported uses of high throughput methodologies for the development of mineral flotation reagents. / Thesis / Doctor of Philosophy (PhD) / Novel cationic polystyrene nanoparticle collectors have been developed to be used as effective flotation collectors, aiming to recover challenging nickel sulfide ores that respond poorly to conventional molecular flotation collectors. However, optimizing nanoparticle flotation collectors is a challenge. This thesis presents a promising approach for discovering and characterizing novel nanoparticle collectors by using high throughput screening techniques and click chemistry. Development of nanoparticle libraries and automated screening assays of critical coagulation concentration and contact angle proved to be effective in obtaining flotation domain maps, and finding the most promising nanoparticle collectors for froth flotation.
69

Development of high-throughput screening method for iron transport inhibitors in E. coli

Hanson, Mathew January 1900 (has links)
Master of Science / Department of Biochemistry and Molecular Biophysics / Phillip Klebba / Iron acquisition is a component of Gram-negative bacteria pathogenesis, therefore as a form of 'nutritional immunity' host organisms sequester iron. To obtain iron bacteria secrete siderophores that scavenge iron. The E. coli outer membrane protein FepA actively transports the siderophore ferric enterobactin into the periplasm. We observe this uptake reaction by fluorescently labeling FepA in live bacteria, monitoring quenching that occurs upon binding of FeEnt, and then fluorescence recovery during transport. Energy poisons azide, arsenate, and 2,4-dinitrophenol were evaluated to determine sensitivity to known transport inhibitors. We developed and optimized methods to screen for iron transport inhibitors using a cell-based high-throughput screening platform. These inhibitors may have broad spectrum bacteriostatic antibiotic properties.
70

THROUGHPUT AND LATENCY PERFORMANCE OF IEEE 802.11E WITH 802.11A, 802.11B, AND 802.11G PHYSICAL LAYERS

Shah, Vishal, Cooklev, Todor 10 1900 (has links)
International Telemetering Conference Proceedings / October 18-21, 2004 / Town & Country Resort, San Diego, California / IEEE 802.11e is an amendment of the medium-access control (MAC) layer of the standard for wireless local area networking IEEE 802.11. The goal of 802.11e is to provide 802.11 networks with Quality of Service (QoS). 802.11 has three physical layers (PHY) of practical importance: 802.11b, 802.11a, and 802.11g. 802.11a and 802.11g provide data rates between 6 and 54 Mbps, and 802.11b provides data rates of 5.5 Mbps and 11 Mbps. However these data rates are not the actual throughput. The actual throughput that a user will experience will be lower. The throughput depends on both the PHY and MAC layers. It is important to estimate what exactly is the throughput when the physical layer is 802.11a, 802.11b, or 802.11g, and the MAC layer is 802.11e. In other words, how does providing QoS change the throughput for each of the three physical layers? In this paper we provide answers to this problem. Analytic formulae are derived. The maximum achievable throughput and minimum delay involved in data transfers are determined. The obtained results have further significance for the design of high-throughput wireless protocols.

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