為了進一步支援無線網路上的服務品質(QoS)，IEEE 802.11e通訊協定目前正在制訂中。其提供兩種媒介存取方式，一為基礎的進階分散存取(EDCA)，另一種是建構在進階分散存取下的混合控制存取(HCCA)。802.11e中，藉由不同的訊框間隔(IFS)與競爭視窗(CW)相關參數的設定以區隔不同的存取等級(AC)。為了在802.11e網路下進一步的發展有效的服務品質管理機制，我們提出了一個數學模型以分析在進階分散存取網路下所使用的頻寬與媒體存取層所延遲的時間。在這個模型下，每個站台可以支援多個不同等級的資料流(聲音/影音與資料)。透過這個數學模型，允入控制與資源管理可以很容易實現，也可以支援不同應用程式的不同需求。 / For supporting Quality of Service (QoS) for wireless networks, the IEEE 802.11 Task Group E currently defines enhancements to the IEEE 802.11 MAC, called 802.11e. The IEEE 802.11e provides two mechanisms for the support of applications with QoS requirements, namely, Enhanced Distributed Channel Access (EDCA) and HCF Controlled Channel Access (HCCA). EDCA mechanism defines four access categories (ACs) that provide support for the delivery of traffic with user priorities. Different AC uses various Inter-Frame Space (IFS) and Contention Window (CW) parameters. In order to further develop efficient QoS management for the IEEE 802.11e networks, we propose an analytical model to evaluate throughput and MAC delay of the basic access method of the IEEE 802.11e - EDCA. Our Markov chains consider the situation of different multimedia (voice/video and data) traffic flows in a mobile station. This is improved from previous work, and closer to real usage scenarios. The correctness of our analysis has been validated via simulation results. Throughout our model, call admission control (CAC) and resource management can be easily applied, and thus QoS for hybrid requirements is supported.

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Nous assistons ces dernières années à une émergence constante de nouvelles applications, notamment pour les services audiovisuels. Ces applications imposent au réseau un certain nombre de contraintes pour qu’elles puissent fonctionner correctement. Le développement de mécanismes permettant d’offrir une garantie à ces contraintes, est donc devenu un objectif crucial. La norme IEEE 802.16j est l’une des solutions sans fil qui propose plus de ressources afin de supporter les nouveaux services de télécommunications. Dans la présente thèse, nous focalisons notre étude sur la problématique de la qualité de service dans les réseaux WiMAX relais. Nos contributions se regroupent à travers les étapes ci-dessous : Nous proposons un protocole de routage multicast pour les services IPTV (HDTV, SD-TV, Web-TV et Mobile-TV). Ce protocole repose d’une part sur un nouveau mécanisme de construction de l’arbre multicast basé sur les nombres premiers et d’autre part, sur une nouvelle méthode d’agrégation basée sur le standard de compression Vidéo «SVC». L’objectif est de supporter l’hétérogénéité des utilisateurs tout en optimisant la consommation des ressources. Par ailleurs, nous étudions le problème d’ordonnancement dans les réseaux WiMAX. Nous proposons un algorithme d’ordonnancement adaptatif AWRR, ce dernier se base sur une technique à charge pondérée. L’objectif est d’ajuster dynamiquement le poids de chaque classe de service, en prenant en compte la charge de la file d’attente et les contraintes de la QoS. Enfin, nous nous intéressons à l’étude de la problématique du chemin optimal contraint. Nous proposons une solution déterministe basée sur une fonction de coût. Notre fonction permet aussi d’assurer le contrôle d’admission, elle se base sur deux fonctions de coût élémentaires qui prennent en compte quatre critères de QoS. / Over recent years, new applications steadily developed in a tremendous space, especially in audiovisual services area. The present applications have some of constraints to work properly. The developments of mechanism which enable to overcome these constraints become a critical issue in this area. The IEEE 802.16j standard is one of wireless communication technology which offering more resources to support new telecommunication services. In this thesis, we focus our research on the problem of quality of service (QoS) inWiMAX relay networks. Our contributions are classified as follows : we proposed a multicast routing protocol for IPTV services (such as HD-TV, SD-TV, Web-TV and Mobile-TV). This proposed protocol used a new multicast tree construction mechanism based-on prime numbers. We also developed a new aggregation method based on standard video compression called Scalable Video Coding (SVC). Our goal is to support user’s heterogeneity while optimizing resources consumption. In addition, we studied the problem of scheduling inWiMAX networks.We proposed an adaptive scheduling algorithm AWRR for IPTV services. The aim of this method is to support QoS constraints by using two schedulers, and assigning a dynamic value to each service queue. Finally, we interested to study about the problem of path selection. We proposed a solution based on a deterministic cost function. This function also ensures admission control based on two basic cost functions which include four QoS criteria. This thesis has been prepared in the MIPS/GRTC laboratory, University of Haute Alsace, under a research contract external (CRE) framework with France Telecom R&D. All proposed mechanisms were evaluated by the simulator QualNet, Matlab and mathematical analysis.

The next generation wireless system (NGWS) has been conceived as a ubiquitous wireless environment. It integrates existing heterogeneous access networks, as well as future networks, and will offer high speed data, real-time applications (e.g. Voice over IP, videoconference ) and real-time multimedia (e.g. real-time audio and video) support with a certain Quality of Service (QoS) level to mobile users. It is required that the mobile nodes have the capability of selecting services that are offered by each provider and determining the best path through the various networks. Efficient radio resource management (RRM) is one of the key issues required to support global roaming of the mobile users among different network architectures of the NGWS and a precise call admission control (CAC) scheme satisfies the requirements of high network utilization, cost reduction, minimum handover latency and high-level QoS of all the connections. This thesis is going to describe an adaptive class-based CAC algorithm, which is expected to prioritize the arriving channel resource requests, based on user¿s classification and channel allocation policy. The proposed CAC algorithm couples with Fuzzy Logic (FL) and Pre-emptive Resume (PR) theories to manage and improve the performance of the integrated wireless network system. The novel algorithm is assessed using a mathematical analytic method to measure the performance by evaluating the handover dropping probability and the system utilization.

In IEEE 802.11 WLANs, Link Adaptation mechanisms, which choose the transmission rate of each node, provoke unexpected and random variations on the effective channel capacity. When these changes are towards lower bitrates, inelastic flows, such as VoIP, can suffer from sudden congestion, which results on higher packet delays and losses. In this thesis, a VoIP codec adaptation algorithm is proposed as a solution, based on a cross-layer feedback from RTCP packets and the MAC layer, which can adapt the codecs of active calls to adjust them to the multirate scenario. A combination of this algorithm with a call admission control mechanism is also studied. The results show an important improvement in terms of the QoS of the already active flows as also in the total hotspot's capacity. Additionally, by defining a new Grade of Service related parameter, the Q-Factor, which captures the trade-off between dropping and blocking ratio and perceived speech quality, the codec adaptation algorithm can be tuned to achieve maximum capacity without severely penalizing any of those variables, and hence satisfying both technical and user quality requirements. Finally, a new QoS-enabled AP, which implements these enhancements is designed. / En las redes inalámbricas del estándar IEEE 802.11, los mecanismos de adaptación de enlace que eligen la tasa de transmisión de cada nodo, pueden provocar variaciones aleatorias e inesperadas en la capacidad efectiva del canal. Cuando estos cambios son hacia tasas de transmisión mas bajas, los flujos inelásticos, tales como los de VoIP, pueden de repente sufrir congestión, lo que se traduce en aumento de retrasos y pérdidas de paquetes. En esa tesis, se propone un algoritmo de adaptación de codificadores de voz como solución, basado en técnicas multinivel (cross-layer) que combinan el uso de información de diferentes capas, como los paquetes RTCP y la capa MAC, y que puede adaptar los codecs de las llamadas activas para ajustarlos al escenario "multi-rate". Adicionalmente, la combinación de este algoritmo con un mecanismo de control de admisión de llamadas (CAC) se ha estudiado. Los resultados muestran una importante mejora en términos de QoS de los flujos activos como también en la capacidad total del hotspot. Además, mediante la definición de un nuevo factor, el Q-Factor, que puede captar la compensación entre la tasa de corte y de bloqueo de llamadas y de la calidad percibida por esas, el algoritmo de adaptación de codecs se puede ajustar para lograr la máxima capacidad sin penalizar severamente ninguna de esas variables y así satisfacer los requisitos técnicos de calidad y los usuarios. Por último, un nuevo punto de acceso (AP) habilitado para ofrecer calidad de servicio, ha sido diseñado que lleva a cabo estas mejoras.

One of the enabling technologies for Long Term Evolution (LTE) deployments is the femtocell technology. By having femtocells deployed indoors and closer to the user, high data rate services can be provided efficiently. These femtocells are expected to be depolyed in large numbers which raises many technical challenges including the handover management. In fact, managing handovers in femtocell environments, with the conventional manual adjustment techniques, is almost impossible to keep pace with in such a rapidly growing femtocell environment. Therefore, doing this automatically by implementing Self Organizing Network (SON) use cases becomes a necessity rather than an option. However, having multiple SON use cases operating simultaneously with a shared objective could cause them to interact either negatively or positively. In both cases, designing a suitable coordination policy is critical in solving negative conflicts and building upon positive benefits. In this work, we focus on studying the interactions between three self optimization use cases aiming at improving the overall handover procedure in LTE femtocell networks. These self optimization use cases are handover, Call Admission Control (CAC) and load balancing. We develop a comprehensive, unified LTE compliant evaluation environment. This environment is extendable to other radio access technologies including LTE-Advanced (LTE-A), and can also be used to study other SON use cases. Various recommendations made by main bodies in the area of femtocells are considered including the Small Cell Forum, the Next Generation Mobile Networks (NGMN) alliance and the 3rd Generation Partnership Project (3GPP). Additionally, traffic sources are simulated in compliance with these recommendations and evaluation methodologies. We study the interaction between three representative handover related self optimization schemes. We start by testing these schemes separately, in order to make sure that they meet their individual goals, and then their mutual interactions when operating simultaneously. Based on these experiments, we recommend several guidelines that can help mobile network operators and researchers in designing better coordination policies. / Thesis (Master, Electrical & Computer Engineering) -- Queen's University, 2012-12-05 22:35:27.538

Les « trois organisations soeurs », à savoir la Commission du Codex Alimentarius (CCA), l’Organisation mondiale de la santé animale (OIE) et la Convention internationale pour la protection des végétaux (CIPV), et les mesures sanitaires et phytosanitaires de l’ASEAN maintiennent une relation mutuellement étroite et des rapports d’interactions complexes et multidimensionnelles, rapports qui peuvent affecter des flux d’activités d’importation et d’exportation de produits agro-alimentaires réglementées surtout par le droit international économique. En envisageant le droit comme processus de décisions, particulièrement le droit international comme processus de communication entre les différents participants de la « communauté mondiale », ces rapports peuvent être mieux identifiés et compris à tous les niveaux : multilatéral, régional, bilatéral et national. Compte tenu de l’intensité et de la fréquence des échanges et du caractère fortement interdépendant du monde d’aujourd’hui, les « trois organisations soeurs » et leurs normes, directives et recommandations sont susceptibles de jouer divers rôles dans la promotion d’une plus grande production et d’un plus large partage des valeurs fondamentales recherchées par l’humanité entière, soutenues par la « New Haven School of International Law ». Non seulement s’agit-il des rôles liés à l’augmentation de l’efficacité du processus de réduction de barrières commerciales résultant des mesures SPS protectionnistes, mais aussi de ceux qui sont peu soulignées et qui se précisent suite aux pratiques répétées des décisionnistes de l’ASEAN. Ce sont notamment les rôles en tant qu’inducteurs de performance pour les mécanismes d’encadrement de mesures SPS, afin de s’assurer que celles-ci sont raisonnables par rapport à chaque contexte spécifique et respectueuses de la dignité humaine ; en tant que catalyseurs du régionalisme ouvert ; et en tant que promoteurs de la dimension du développement dans les accords commerciaux régionaux de l’ASEAN. / The « three sisters », namely the Codex Alimentarius Commission (CAC), the World Organisation for Animal Health (OIE) and the International Plant Protection Convention (IPPC), and SPS measures of ASEAN maintain a mutually close relationship and can interact with one another in complex and multidimensional ways, which can affect flows of import and export activities of agro-food products regulated especially by international economic law. By perceiving law as a process of decisions, and particularly international law as a process of communication among different participants of the « world community », these interactions can be better identified and comprehended at all levels : multilateral, regional, bilateral and national. Considering the intensity and frequency of exchanges and the strong interdependency of today’s world, the « three sisters » and their standards, guidelines and recommendations are likely to play numerous roles in promoting a greater production and wider distribution of fundamental values that all human beings desire to maximize and achieve, as defended by the « New Haven School of International Law ». Not only are these roles related to the promotion of a more efficient process of eliminating trade barriers deriving from SPS protectionist measures, but also those which are insufficiently highlighted, yet becoming more obvious through repeated practices of ASEAN decision-makers. These are notably the roles of the « three sisters » as performance drivers for monitoring mechanisms of SPS measures with a view to ensuring that they are reasonable in each specific context and respectful towards human dignity; as catalysts of open regionalism ; as promoters of the development dimension in regional trade agreements concluded by ASEAN.

No description available.

The thesis deals with study of mechnochemical activation of chemical reactions at interphase of MDF composites. MDF composites are high-perspective composite materials on polymer-cement base. They excel especially in terms of flexural strengths. High flexural stregth is caused by binding interactions between the polymer and the cement. This interactions arise due to mechanochemical activation of raw material mixture at the stage of production. This work focuses on the creation of artificial cement-polymer interphase by contacting the surfaces of two molded tablets (polyvinyl alcohol and monocalcium aluminate), activation of chemical reactions at interphase by means of specially designed appartus, which achieves good plane-parallelism of activation surfaces and good definability of activation conditions (shear rate, pressure). After experiments under different conditions, the activated surfaces are analyzed by SEM, EDS, XPS and FT-IR.

Petroleum powered vehicles emit volatile organic compounds (VOCs) through combustion that contributes to the pollution of the environment. A technique in the 1970s was developed to decrease these emissions, especially for nitrogen oxides (NOx) and sulphuric oxides (SOx) which is called exhaust gas recirculation (EGR). The technique works by recirculating a portion of the combusted gas back into the engine, this limits the NOx and SOx emissions because of lower temperatures and less available oxygen. The problems that follow these effects is the formation and condensation of acids that corrode the material of the EGR system, which are created by many different reactions. It is of importance to understand how the compounds in the EGR system behaves through analysis of authentic and simulated condensates, which is why a quantitative method for these compounds are of interest. The aim of the project was to develop a simple quantitative analysis method for formic acid, acetic acid, and lactic acid in aqueous solution, which was done at Gränges Sweden AB. The technique used for detection and quantification was gas chromatography (GC) coupled to a flame ionization detector (FID) and a water compatible polyethylene glycol (PEG) column. Fractional factorial design (FFD) was used for determination of adequate operating parameters of the GC method and the sample preparation. Sample preparation only required filtration and pH adjustment prior to direct aqueous injection (DAI) to the chromatographic instrument. Detection of the analytes was very difficult because of non-compatibility with the FID, and quantification of asymmetric peak shapes made this problem worse, omitting lactic acid from further analysis. Limit of detection (LOD) and limit of quantification (LOQ) was 490 and 1640 ppm for formic acid and 120 and 400 ppm for acetic acid, with an injection volume of 0.3 μL and split ratio 10:1. Limits were too high for every EGR sample leaving no peaks detected for the sample preparation used. Further development should be done with complementary techniques and sample reprocessing in order to quantify the compounds.