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Bluetooth QoS SchedulerJonsson, Björn January 2003 (has links)
Bluetooth is a low cost, short-range radio technology that enables electronic devices to communicate wirelessly via ad-hoc networks. Different kinds of applications may run over these networks, some of these applications with particular Quality of Service (QoS) requirements. One such application could for instance be an Audio application which need data frames to be delivered at regular interval to work properly. The communication over Bluetooth links is totally controlled by one of the participating nodes. Since this node controls the traffic and thereby controls the QoS within the network its communicating behaviour is of great importance for maintaining QoS reservations. A central part in maintaining QoS reservations is the scheduler, which prioritises between different tasks to be done such as which device that is allowed to transmit next. There is no standardised way to implement the Bluetooth scheduler. However, a Bluetooth scheduler should be able to handle QoS reservations, maintain fairness among the participating nodes, and utilise the available bandwidth efficiently. Furthermore a key requirement in Bluetooth is simplicity, therefore a Bluetooth scheduling algorithm should be of low complexity. This master thesis presents a new patented solution for an intra-piconet scheduling algorithm that is capable of maintaining QoS reservation, while being fair and also meet the low complexity requirement. This algorithm is presented in detail in the thesis and has been implemented in an ns2- based Bluetooth simulator. Simulations in this simulator are presented that verifies the scheduling algorithms functionality. / Bluetooth är en standard för trådlös ad-hoc kommunikation. Denna standard definierar i antalet noder begränsade nätverk (piconet) som kan kopplas samman till större nätverk (scatternet). Många olika typer av applikationer kan tänkas använda dessa nätverk, vissa av dessa med speciella krav på Quality of Service (QoS). Ett exempel så en dylik applikation är ljudöverföringar som kräver att data överförs med jämna mellanrum för att kunna fungera tillfredställande. Kommunikationen över ett Bluetooth-piconet kontrolleras helt av en av de deltagande enheterna. Eftersom denna enhet kontrollerar trafiken kontrollerar den också upprätthållandet av QoS reservationerna. En central del i detta upprätthållande är schemaläggaren, som är den del i en Bluetoothenhet som prioriterar mellan olika saker som ska utföras. Ett exempel på en sådan prioritering kan vara vilken enhet i nätverket som ska få kommunicera härnäst. Bluetooth standarden beskriver inte hur denna schemaläggare ska implementeras. Grundläggande krav på en Bluetooth schemaläggare är att den ska kunna hantera och upprätthålla QoS reservationer samtidigt som den delar den befintliga kapaciteten på ett rättvist och effektivt sätt mellan de deltagande enheterna. Vidare bör den ha en låg komplexitet eftersom enkelhet är ett krav på alla delar i ett Bluetoothsystem. Detta examensarbete presenterar en ny patenterad algoritm för schemaläggning i begränsade Bluetoothnät som är kapabel att upprätthålla QoS-reservationer, samtidigt som den distribuerar den tillgängliga kapaciteten på ett rättvist sätt. Algoritmen möter också upp till kravet på låg komplexitet. Rapporten innehåller vidare simuleringar av algoritmens funktion, dessa har utförts i en ns2-baserad Bluetooth miljö och verifierar algoritmens funktionalitet.
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A Selective Approach to Bandwidth OverbookingHuang, Feng 23 March 2006 (has links) (PDF)
Overbooking is a technique used by network providers to increase bandwidth utilization. If the overbooking factor is chosen appropriately, additional virtual circuits can be admitted without degrading quality of service for existing customers. Most existing implementations use a single factor to accept a linear fraction of traffic requests. High values of this factor may cause the degradation of quality of service whereas low overbooking factors will result in underutilization of bandwidth. Network providers often select overbooking factors based only on aggregate average virtual circuit utilization. This paper proposes a selective overbooking scheme based on trunk size and usage profile. Experiments and analysis show that the new overbooking policy results in a superior network performance.
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Calidad de servicio en transmisiones de datosCaba, Fernando Antonio 03 July 2014 (has links)
La gran cantidad de contenidos puestos a disposición de los usuarios en Internet,
ha exigido estudiar la conveniencia de aplicación de diversas técnicas para mejorar la
performance de las redes de telecomunicaciones, las cuales son afectadas por retardos,
variación del retardo, ancho de banda y pérdida de paquetes. Dado que, estos
parámetros están presentes permanentemente, que a veces no pueden mejorarse por
cuestiones físicas y que las aplicaciones poseen requerimientos para su correcto
funcionamiento, estas propiedades deben ajustarse dentro de ciertos límites para
garantizar a los usuarios la entrega de la información, priorizar el tráfico, minimizar y
controlar la congestión, entre otras cosas. Estos límites se acuerdan entre cliente y
proveedor mediante Acuerdos de Niveles de Servicio. Desde los comienzos del
desarrollo de Internet, estuvo presente un servicio de entrega de datos denominado
Mejor Esfuerzo, el cual se caracteriza por la no aplicación de técnicas orientadas a
brindar calidad de servicio. Las aplicaciones envían paquetes de datos cada vez que
deben hacerlo, en la cantidad que necesiten y sin ningún tipo de permiso ni informe a la
red de datos sobre los requerimientos de la transmisión. Resulta innegable que un
modelo de estas características no posee la mejor performance ni el mejor desempeño.
Para dar soporte a este gran volumen de tráfico se han desarrollado arquitecturas de
calidad de servicio que plantean modelos para mejorar la performance de las
aplicaciones. El primer modelo se denomina Arquitectura de Servicios Integrados y se
caracteriza por analizar el tráfico y aplicar reservas de ancho de banda a determinados
flujos de datos asociados a sesiones individuales. En función de cuan tolerante al
retardo, a su variación y a la pérdida de paquetes sea una aplicación, se utilizan los
servicios Garantizados y de Carga Controlada. El primero aplica estrictos límites de
retardo y el segundo es utilizado en ambientes donde las aplicaciones pueden aceptar un
cierto grado de variación del retardo. El segundo modelo se denomina Arquitectura de
Servicios Diferenciados y se caracteriza por proporcionar diferentes niveles de servicio
al tráfico mediante su clasificación en grupos denominados clases. La aplicación de
cada una de estas, otorgará al flujo de datos un tratamiento predefinido para el reenvío
de paquetes. El enfoque de la arquitectura de Servicios Diferenciados se encuentra en
algún punto entre el servicio de Mejor Esfuerzo y la arquitectura de Servicios
Integrados, pues, trata de dar un paso más allá del modelo de mejor esfuerzo para
ofrecer un servicio mejor que el de mejor esfuerzo. En el presente trabajo se estudiarán
técnicas para evitar y controlar la congestión, como así también la aplicación de la
aplicación de políticas y modelado del tráfico. Este desarrollo inicial, complementa la
posterior descripción de las arquitecturas de calidad de servicio mencionadas. / The vast quantity of content at Internet users’ disposal has demanded the
consideration of applying diverse techniques to improve web performance in
telecommunication seriously affected by delay, delay variation (jitter), bandwidth and
packet loss. As these parameters are permanently present, sometimes it is not possible to
improve them both due to physical reasons and the fact that applications possess
requirement for their correct functioning, those properties must be adjusted within
certain limits to guarantee users’ information delivery, prioritize traffic, minimize and
control congestion and so on. Such limits are agreed upon between client and provider
by Service Level Agreements. From the beginning of Internet development, a delivery
service called Best Effort has been present characterised by not applying techniques
oriented to provide quality of service. Applications send data packets each time they
must, in the quantity needed and with neither permission nor report to the network of
transmission requirements data. It goes without saying that such model does not
perform or function well. Quality of Service Architectures has been developed to
support this vast volume of traffic establishing models to improve applications
performance. The first one is called Integrated Services Architecture, it analyses traffic
and applies bandwidth reserves to determined data flows associated to individual
sessions. Guaranteed and Controlled Load services are used depending on how tolerant
is an application to delay, jitter and packet loss. The first one applies strict delay limits
and the second one is used when applications can accept certain degree of jitter. The
second architecture is called Differentiated Services and it provides different levels of
services through sorting traffic in groups called classes. The use of each one of this will
provide the data flow with predefined treatment for packet forwarding. The Architecture
of Differentiated Services locates itself between the Best Effort service and the
Integrated Services Architecture because it tries to go a step forward beyond the Best
Effort model to offer a better service. The present work studies the techniques to control
and avoid congestion as well as the application of policies and traffic modelling. This
initial development complements the subsequent description of the service quality
architectures above mentioned.
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Localised routing algorithms in communication networks with Quality of Service constraints : performance evaluation and enhancement of new localised routing approaches to provide Quality of Service for computer and communication networksMohammad, Abdulbaset H. T. January 2010 (has links)
The Quality of Service (QoS) is a profound concept which is gaining increasing attention in the Internet industry. Best-effort applications are now no longer acceptable in certain situations needing high bandwidth provisioning, low loss and streaming of multimedia applications. New emerging multimedia applications are requiring new levels of quality of services beyond those supported by best-effort networks. Quality of service routing is an essential part in any QoS architecture in communication networks. QoS routing aims to select a path among the many possible choices that has sufficient resources to accommodate the QoS requirements. QoS routing can significantly improve the network performance due to its awareness of the network QoS state. Most QoS routing algorithms require maintenance of the global network's state information to make routing decisions. Global state information needs to be periodically exchanged among routers since the efficiency of a routing algorithm depends on link-state information accuracy. However, most QoS routing algorithms suffer from scalability due to the high communication overhead and the high computation effort associated with maintaining accurate link state information and distributing global state information to each node in the network. The ultimate goal of this thesis is to contribute towards enhancing the scalability of QoS routing algorithms. Towards this goal, the thesis is focused on Localised QoS routing algorithms proposed to overcome the problems of using global network state information. Using such an approach, the source node makes routing decisions based on the local state information for each node in the path. Localised QoS routing algorithms avoid the problems associated in the global network state, like high communication and processing overheads. In Localised QoS routing algorithms each source node maintains a predetermined set of candidate paths for each destination and avoids the problems associated with the maintenance of a global network state by using locally collected flow statistics and flow blocking probabilities.
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Hodnocení kvality sportovních a tělovýchovných služeb / Evaluation of the Quality of Sports ServicesSkryja, Tomáš January 2015 (has links)
This Master thesis deals with comparing the quality of the sport services in two male football clubs SK Buwol Metal Luka nad Jihlavou and SV Lausitz Forst. The research is performed both through the method of questionnaire the method known as SERVQUAL. The theoretical part deals with defining the concept of service itself; moreover it describes the service in sport in general and also the quality of service in sport. Furthermore, it includes methods for measuring the service quality. In the practical part, the results of questionnaires are analyzed, evaluated and interpreted. In addition, this part also includes suggested measures for improving the service quality of the examined football clubs.
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An Evaluation of IoT Application ProtocolsFatohi, Kristian January 2023 (has links)
Hur vi människor kommer att leva i framtiden kan kraftigt påverkas utav konceptet Internet of Things. IoT erbjuder unika möjligheter för att hjälpa oss människor att automatisera och förenkla vissa ärenden. Även om koncpetet har funnits ett tag så har man fortfarande vilseledda åsikter kring potentialen med IoT. Det intressanta med konceptet och vad som enligt mig är den fundamentala grunden för IoT är självaste kommunikationen. Men hur går kommunikation till? Ett flertal IoT kommunikationsprotokoll har utvecklats för att försöka förbättra kommunikationen mellan två och flera smarta enheter. Eftersom det finns ett par olika kommunikationsprotokoll så är målet för denna studie att utvärdera och undersöka prestandan för befintliga applikations lagrade kommunikationsprotokoll. En litteraturrecension görs för att identifiera och få en djupare förståelse för deras unika egenskaper som skiljer protokollen åt. Alla protokoll som tas upp i denna rapport kommer inte att undersökas och valet av vilka protokoll som ska inspekteras närmare gjordes genom en jämförande analys där faktorer som kommunikationsmetod och begränsningen av nyttolast storleken beaktades. Latens, genomströmning och skalbarheten är de prestandafaktorerna som bedöms för de protokoll som valts för en närmare inspektion. Resultaten av dessa tester används för att dra slutsatser om lämpligheten för varje protokoll. Efter en omfattande utvärdering baserat på de experimenten som gjorts under projektets gång så drar denna rapport slutsatsen att MQTT och CoAP är de mest lämpliga protokollen för allmänna IoT-applikationer på grund av deras lätta, effektiva och skalbara natur. / The Internet of Things is a concept that has gained widespread attention and adaptation all around the world, but few people really do understand how it works and what it really is. The concept revolutionized the way we interact with our surroundings, it revolves around connectivity between smart devices and how they communicate with other devices or with humans. To ensure effective communication, a set of application layered protocols has been developed. These protocols are designed to be beneficial in certain areas, which is why the objective for this study has been to evaluate and examine the performance of existing application communication protocols. A thorough literature review is conducted to identify and gain a deeper understanding of their unique characteristics and features for some protocols that exist and are used today. All protocols brought up in this thesis will not be examined and choosing which protocols to inspect further was done by doing a comparative analysis where factors such as, communication method and payload limit size were taken into consideration. Performance assessment was done for the protocols that qualified, where factors like latency, throughput, and scalability were measured. The results of these tests are used to draw conclusions about the suitability of each protocol. After a comprehensive evaluation based on experiments with simulations and literature reviews, this thesis concludes that MQTT and CoAP as the most suitable protocols for general IoT applications due to their lightweight, efficient, and scalable nature.
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Localised Routing Algorithms in Communication Networks with Quality of Service Constraints. Performance Evaluation and Enhancement of New Localised Routing Approaches to Provide Quality of Service for Computer and Communication Networks.Mohammad, Abdulbaset H. T. January 2010 (has links)
The Quality of Service (QoS) is a profound concept which is gaining increasing attention in the Internet industry. Best-effort applications are now no longer acceptable in certain situations needing high bandwidth provisioning, low loss and streaming of multimedia applications. New emerging multimedia applications are requiring new levels of quality of services beyond those supported by best-effort networks. Quality of service routing is an essential part in any QoS architecture in communication networks. QoS routing aims to select a path among the many possible choices that has sufficient resources to accommodate the QoS requirements. QoS routing can significantly improve the network performance due to its awareness of the network QoS state. Most QoS routing algorithms require maintenance of the global network¿s state information to make routing decisions. Global state information needs to be periodically exchanged among routers since the efficiency of a routing algorithm depends on link-state information accuracy. However, most QoS routing algorithms suffer from scalability due to the high communication overhead and the high computation effort associated with maintaining accurate link state information and distributing global state information to each node in the network. The ultimate goal of this thesis is to contribute towards enhancing the scalability of QoS routing algorithms. Towards this goal, the thesis is focused on Localised QoS routing algorithms proposed to overcome the problems of using global network state information. Using such an approach, the source node makes routing decisions based on the local state information for each node in the path.
Localised QoS routing algorithms avoid the problems associated in the global network state, like high communication and processing overheads. In Localised QoS routing algorithms each source node maintains a predetermined set of candidate paths for each destination and avoids the problems associated with the
maintenance of a global network state by using locally collected flow statistics and flow blocking probabilities. / Libya's higher education
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QoS Performance Management in Mixed Wireless NetworksAstatke, Yacob 10 1900 (has links)
ITC/USA 2010 Conference Proceedings / The Forty-Sixth Annual International Telemetering Conference and Technical Exhibition / October 25-28, 2010 / Town and Country Resort & Convention Center, San Diego, California / This paper presents a model for Quality of Service (QoS) management in a mix of fixed Ground Station (GS) and ad-hoc telemetry networks, and introduces an enhanced clustering scheme that jointly optimizes the performance of the network using multiple distance measures based on the location of the wireless nodes and the traffic level. It also demonstrates that a "power" performance measure is an effective tool for modeling and managing QoS in Mixed Networks. Simulation results show that significant QoS performance improvements can be obtained and maintained even under severe traffic conditions.
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Distributed multimedia quality : the user perspectiveGulliver, Stephen Richard January 2004 (has links)
Distributed multimedia supports a symbiotic infotainment duality, i.e. the ability to transfer information to the user, yet also provide the user with a level of satisfaction. As multimedia is ultimately produced for the education and / or enjoyment of viewers, the user’s-perspective concerning the presentation quality is surely of equal importance as objective Quality of Service (QoS) technical parameters, to defining distributed multimedia quality. In order to extensively measure the user-perspective of multimedia video quality, we introduce an extended model of distributed multimedia quality that segregates quality into three discrete levels: the network-level, the media-level and content-level, using two distinct quality perspectives: the user-perspective and the technical-perspective. Since experimental questionnaires do not provide continuous monitoring of user attention, eye tracking was used in our study in order to provide a better understanding of the role that the human element plays in the reception, analysis and synthesis of multimedia data. Results showed that video content adaptation, results in disparity in user video eye-paths when: i) no single / obvious point of focus exists; or ii) when the point of attention changes dramatically. Accordingly, appropriate technical- and user-perspective parameter adaptation is implemented, for all quality abstractions of our model, i.e. network-level (via simulated delay and jitter), media-level (via a technical- and user-perspective manipulated region-of-interest attentive display) and content-level (via display-type and video clip-type). Our work has shown that user perception of distributed multimedia quality cannot be achieved by means of purely technical-perspective QoS parameter adaptation.
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Integration of Wireless Sensor Networks Into a Commercial Off-the-Shelf (COTS) Multimedia Network.Molineux, Jeffrey S. 25 July 2012
As the primary military operating environment shifts from the traditional battlefields to a more diverse urban environment, the use of remote wireless sensors is increasing. Traditional development and procurement methods are not capable of meeting the changing requirements and time constraints of commanders. To minimize the time to develop and deploy new systems, commercial solutions must be examined. The focus of this thesis is on the integration of Commercial Off-the-Shelf (COTS) components into a wireless multimedia sensor network. Because components from multiple vendors were utilized, different operating systems and transmission protocols had to be integrated across the network. The network must be capable of providing a varying Quality of Service (QoS) level depending on the active sensors in the network. To ensure the QoS level is met, an adaptive QoS algorithm was implemented in the wireless IEEE 802.11 router which monitored and measured the outgoing transmission interface; from which, it determined the latency and transmission jitter. Based on the results, the program can adjust the bandwidth as necessary. Finally, a user interface is developed that allows end users to monitor the network. The performance of the network is based on the end-to-end throughput, latency and jitter exhibited by the network.
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