Κύριος στόχος της διπλωματικής αυτής εργασίας είναι η διερεύνηση τεχνικών βελτίωσης της προσφερόμενης ποιότητας υπηρεσιών (QoS) σε ένα περιβάλλον συνλειτουργίας πολλαπλών HAPs. Στο περιβάλλον αυτό έχουμε διαφορετικούς τύπους χρηστών που μοιράζονται την περιοχή κάλυψης και το εύρος ζώνης. Παρουσιάζεται το θεωρητικό υπόβαθρο της μελέτης αυτής που περιλαμβάνει τη θεωρία τηλεπικοινωνιακής κίνησης. Αναπτύσσουμε ένα αναλυτικό μοντέλο ώστε να περιγράψουμε το περιβάλλον συνλειτουργίας στο οποίο έχουμε δύο κατηγορίες χρηστών. Η μία κατηγορία αποτελείται από χρήστες που έχουν πλήρη πρόσβαση στα HAPs, ενώ η άλλη κατηγορία αποτελείται από χρήστες με περιορισμένη πρόσβαση στα HAPs. Για να επιτύχουμε αυτή τη βελτίωση του QoS εφαρμόζουμε διάφορους μηχανισμούς περιορισμού. Σκοπός μας είναι να περιοριστεί η πρόσβαση στους πόρους του καναλιού για τους χρήστες με πλήρη πρόσβαση στα HAPs, ώστε να υπάρχει μεγαλύτερη πιθανότητα πρόσβασης για τους χρήστες με περιορισμένη πρόσβαση στα HAPs. Παρουσιάζονται και αναλύονται διάφοροι περιορισμοί με στόχο την εύρεση του καταλληλότερου για την επίτευξη μιας ισορροπημένης και χαμηλής πιθανότητας απόρριψης κλήσης. Αναλύεται, επίσης, και επεξηγείται η παρουσία φαινομένων παρεμβολής και πολυόδευσης στο σύστημά μας καθώς και η εξοικονόμηση συχνοτήτων. / The main objective of this thesis is to investigate techniques for improvement the Quality of Service (QoS) in an environment of multiple HAPs. In this environment there are different user types which share coverage area and radio spectrum. It is presented the theoretical background of this study that includes theory telecommunication traffic. We develop an analytical model to describe system behavior of a coexistence scenario containing two user groups, which have full and limited HAP availability. In order to achieve this improvement of QoS, operate different restrictions. Our aim is to limit access to channel resources to users with full access to HAPs, so that there is a greater probability of access for users with limited access to HAPs. Different types of restriction function are analyzed trying to find the most suitable for achieving a balanced low probability performance to both user groups simultaneously. It is also explained the presence of interference, small-scale fading and saving frequencies.

Depuis quelques années, il y a un réel changement dans les usages des réseaux en termes d'applications véhiculées ainsi que dans leur nombre. On voit apparaître de plus en plus d'applications contraintes en termes de délai, comme par exemple la téléphonie sur IP, ainsi que d'applications gourmandes en ressources comme par exemple le Srteaming Video. La croissance en volume de ces applications copmmence à poser des problèmes de congestion dasn les réseaux filiares et sans fil. Les opérateurs réseaux doivent être capables d'absorber ces changements de trafic, de faire face à cette demande de plus en plus intensive en bande passante et de fournir une bonne qualité (QoS) aux applications. Cela nécessite des mécanismes intellignets en termes d'ordonnancement et de gestion des files d'attente, de contrôle d'admission, de contrôle de débit et/ou de routage. L'objectif initial de cette thèse étati d'aboutir à la conception d'une nouvelle architecture de traitement et de gestion du trafic et de la qualité de service pour le contrôle d'admission. Plus précisément nous présentons une nouvelle solution pour le contrôle d'admission qui repose sur l'élaboration en continu d'un plan de connaissance et sur la modélisatio automatique du comportement d'un lien réseau par une file d'attente monoserveur. Norte solution doit permettre d'offrir une garantie probabiliste d'un paramètre de performance QoS qui peut être le délai d'attente moyen des paquets dans le buffer du lien ou le taux de perte. Nous avons évalué les performances de notre nouveau contro^le d'admission par simulation en considérant diverses conditions possibles de trafic. Lers résultats obtenus indiquent que la solution proposée permet d'atteindre un contrôle d'admission ni trop conservateur, ni trop permissif. En outre, notre solution offre l'avantage de se baser uniquement sur une connaisssance acquise au cours du temps et permet ainsi de s'affranchir d'un paramétrage compliqué des paramètres comme c'est le cas pour les solutions classiques de contrôle d'admission / Over the las few years, new ussages such as streaming or live video watching are increasingly representing a significant part of Internet traffic. Network operators face the challenge of satisfying the quality of experience expected by end-users while, in the same time, avoiding the over-provisioning of transmission links. Bandwidth management offers a wide spectrum of policies to overcome this issue. Possible options include congestion control, scheduling algorithms, traffic shaping and admission control. The initial objective of this thesis was to design of a new architecture of traffic management and quality of service for admission control. More precisely, we introduce a novel data-driven method based on a time-varying model that we refer to as Knowledge-Based Admission Control solutions (KBAC). Our KBAC solution consists of three main stages : (i) collect leasurments on the on-going traffic over the communication link ; (ii) maintain an up-to-date broad view of the link behavior, and feed it to a Knowledge Plane ; (iii) model the observed link behavior by a mono-server queue whose parameters are set auutomatically and which predicts the expected QoS if a flow requesting admission were to be accepted. our KBAC solution provides a probalistic guarantee whose admission thresold is either expressed, as a bounded dealy or as a bounded loss rate. We run extensive siçmulations using various traffic conditions to assess the behavior of our KBAC solution in the case of a delay thresold. The results show that our KBAC solution leads to a good trade-off between flow performance and resource utilization. This ability stems from the quick and autoamtic adjustment of its admission policy according to the actual variations on the traffic conditions. On the other hand, our KBAC solution avoids the critical step of precisely calibrating key parameters.

Este trabalho propõe políticas para servidores Web baseados em sessões, visando ao oferecimento de garantias de qualidade de serviço (Quality of Service - QoS) a seus usuários. Para o fornecimento de QoS, dois tipos de políticas são consideradas: as responsáveis pela diferenciação de serviços e as responsáveis pelo controle de admissão. Alguns algoritmos de escalonamento foram desenvolvidos com o objetivo de oferecer melhores serviços para as sessões prioritárias: o algoritmo de escalonamento baseado em sessão (SBSA) e o algoritmo de escalonamento baseado em sessão com diferenciação de serviços (SBSA-DS). Quanto ao controle de admissão, foram consideradas duas novas políticas, as quais utilizam diferentes parâmetros para a tomada de decisão e têm como objetivo garantir a finalização do maior número de sessões prioritárias. A partir dos resultados obtidos nos experimentos realizados por meio de simulação, constatou-se que o emprego dos algoritmos e das políticas desenvolvidos melhora o atendimento das sessões para as quais deve ser oferecido um serviço preferencial. Portanto, em servidores Web preocupados com a garantia de QoS para seus usuários, os quais interagem com o sistema por meio de sessões, o uso dessas novas técnicas se mostra adequado / This work considers policies for Web servers based on sessions, aiming at the guarantees of Quality of Service (QoS) to the systems users. Two types of policies are considered: the responsible for the differentiation of services and the responsible for the admission control. Some scheduling algorithms had been developed to offer better services for the priority sessions: the Session Based Scheduling Algorithm (SBSA) and the Session Based Scheduling Algorithm with Differentiation of Services (SBSA-DS). In relation to the admission control, two new policies had been considered, which use different parameters to help the decisions and have as objective guarantee the finalization of as many priority sessions as possible. From the obtained results of the experiments realized by mean of simulation, it is evidenced that the use of the developed algorithms and policies improves the attendance of the sessions that deserve preferential service. Therefore, in Web servers worried in the guarantee the QoS for their users, which interact with the system by sessions, the use of these new techniques reveals adequate

Subject of this thesis was the issue of effectiveness of wireless networks from the perspective of services. Become acquainted with WiFi network standard IEEE 802.11 with protocols and principles of WiFi networks and services. It should be focused on the quality of service QoS. In teoretical part of this thesis are described problems considering wireless networks, layer model and types of nets used in WiFi. Standard IEEE 802.11 is analysed in details including supplements and used packets. Special attention is paid to the quality of service QoS. Next are discussed the principles and application services as VoIP, videoconferencing, video streaming and others in WiFi network. On the basis of obtained knowledge is designed extensive WiFi network with assured supply of services. For modelling and simulation of wireless network is used software development environment Opnet Modeler. Model of wireless network is used to optimize and analyse this wireless communication network. In thesis are also simulated properties of data which are sensitive to delay. In last part of thesis is created a laboratory work, which contains a submission of task, detailed theory, wiring diagram, instructions for elaboration, guidelines for simulation and example of elaboration of task. Work is about comparison of network with used 802.11b and 802.11e standard, and support of quality of service QoS.

Modern technologies are growing and Voice over Internet Protocol (VoIP) technology is able to function in heterogeneous networks. VoIP gained wide popularity because it offers cheap calling rates compared to traditional telephone system and the number of VoIP subscribers has increased significantly in recent years. End users need reliable and acceptable call quality in real time communication with best Quality of Service (QoS). Server complexity is increasing to handle all client requests simultaneously and needs huge processing power. VoIP Servers will increase processing power but the engineering tradeoff needs to be considered e.g. increasing hardware will increase hardware complexity, energy consumption, network management, space requirement and overall system complexity. Modern System-on-Chip (SoC) uses multiple core technology to resolve the complexity of hardware computation. With enterprises needing to reduce overall costs while simultaneously improving call setup time, the amalgamation of VoIP with SoC can play a major role in the business market. The proposed VoIP Server model with multiple processing capabilities embedded in it is tailored for multicore hardware to achieve the required result. The model uses SystemC-2.2.0 and TLM-2.0 as a platform and consists of three main modules. TLM is built on top of SystemC in an overlay architectural fashion. SystemC provides a bridge between software and hardware co-design and increases HW & SW productivity, driven by fast concurrent programming in real time. The proposed multicore VoIP Server model implements a round robin algorithm to distribute transactions between cores and clients via Load Balancer. Primary focus of the multicore model is the processing of call setup time delays on a VoIP Server. Experiments were performed using OpenSIP Server to measure Session Initiation Protocol (SIP) messages and call setup time processing delays. Simulations were performed at the KTH Ferlin system and based on the theoretical measurements from the OpenSIP Server experiments. Results of the proposed multicore VoIP Server model shows improvement in the processing of call setup time delays.

Traditionally the Internet is used for the following applications: FTP, e-mail and Web traffic. However in the recent years the Internet is increasingly supporting emerging applications such as IP telephony, video conferencing and online games. These new applications have different requirements in terms of throughput and delay than traditional applications. For example, interactive multimedia applications, unlike traditional applications, have more strict delay constraints and less strict loss constraints. Unfortunately, the current Internet offers only a best-effort service to all applications without any consideration to the applications specific requirements. In this thesis three existing Active Queue Management (AQM) mechanisms are modified by incorporating into these a control function to condition routers for better Quality of Service (QoS). Specifically, delay is considered as the key QoS metric as it is the most important metric for real-time multimedia applications. The first modified mechanism is Drop Tail (DT), which is a simple mechanism in comparison with most AQM schemes. A dynamic threshold has been added to DT in order to maintain packet queueing delay at a specified value. The modified mechanism is referred to as Adaptive Drop Tail (ADT). The second mechanism considered is Early Random Drop (ERD) and, iii in a similar way to ADT, a dynamic threshold has been used to keep the delay at a required value, the main difference being that packets are now dropped probabilistically before the queue reaches full capacity. This mechanism is referred to as Adaptive Early Random Drop (AERD). The final mechanism considered is motivated by the well known Random Early Detection AQM mechanism and is effectively a multi-threshold version of AERD in which packets are dropped with a linear function between the two thresholds and the second threshold is moveable in order to change the slope of the dropping function. This mechanism is called Multi Threshold Adaptive Early Random Drop (MTAERD) and is used in a similar way to the other mechanisms to maintain delay around a specified level. The main focus with all the mechanisms is on queueing delay, which is a significant component of end-to-end delay, and also on reducing the jitter (delay variation) A control algorithm is developed using an analytical model that specifies the delay as a function of the queue threshold position and this function has been used in a simulation to adjust the threshold to an effective value to maintain the delay around a specified value as the packet arrival rate changes over time. iv A two state Markov Modulated Poisson Process is used as the arrival process to each of the three systems to introduce burstiness and correlation of the packet inter-arrival times and to present sudden changes in the arrival process as might be encountered when TCP is used as the transport protocol and step changes the size of its congestion window. In the investigations it is assumed the traffic source is a mixture of TCP and UDP traffic and that the mechanisms conserved apply to the TCP based data. It is also assumed that this consists of the majority proportion of the total traffic so that the control mechanisms have a significant effect on controlling the overall delay. The three mechanisms are evaluated using a Java framework and results are presented showing the amount of improvement in QoS that can be achieved by the mechanisms over their non-adaptive counterparts. The mechanisms are also compared with each other and conclusions drawn.

As the number of people using wireless networks is increasing, the need to reduce the vulnerability of wireless networks from node or link failures that cause loss of data is becoming a priority. Also the present techniques and topologies used for wireless networking are not sufficient to handle the traffic load even if we solve the issues of reliability and resilience. Packet loss or delay is increasingly likely due to the increase in the number of packets as technology is evolving and more video and voice packets along with the data packets are being transmitted. Only the efficient and intelligent use of the shared medium can solve the problem and help in avoiding the collision or delay among the packets using a newly proposed intelligent topology. Wireless technology offers the potential to replace wires from many applications, particularly for the rapid deployment of networks for permanent or temporary use. Fiber_ optic metropolitan area networks (WAN) provide security and resilience. A target of the research was to match this in the wireless environment. This research investigates the suitability if using wireless technology for the establishment of a MAN by adding features to enhance resilience. We proposed a mechanism that may be rapidly deployed and provide automatic configuration. Research work and simulation design has been used to develop a new wireless network topology for an efficient and intelligent packet transmission by identifying reliable routes. This novel idea will help give wireless as well as mobile technology a clear edge over wired technology, not only in the case of mobility but also in the case of security of data and other services. A decision based routing tree mechanism has been developed, that can establish routes in an ad-hoc network which may than be configured into a logical dual ring. At the same time the proposed system proposes to embed the quality of service mechanisms, resilience, and reliability features from RPR. The simulations were created using Microsoft Visual Studio.Net for the Decision based routing algorithm. The results were compared with an existing LAR algorithm. We have obtained 95% confidence intervals on all the performance analysis results to indicate accuracy.

The exponential growth of Internet applications has created new challenges for the control and administration of large-scale networks, which consist of heterogeneous elements under dynamically changing traffic conditions. These emerging applications need guaranteed service levels, beyond those supported by best-effort networks, to deliver the intended services to the end user. Several models have been proposed for a Quality of Service (QoS) framework that can provide the means to transport these services. It is desirable to find efficient routing strategies that can meet the strict routing requirements of these applications. QoS routing is considered as one of the major components of the QoS framework in communication networks. In QoS routing, paths are selected based upon the knowledge of resource availability at network nodes and the QoS requirements of traffic. Several QoS routing schemes have been proposed that differ in the way they gather information about the network state and the way they select paths based on this information. The biggest downside of current QoS routing schemes is the frequent maintenance and distribution of global state information across the network, which imposes huge communication and processing overheads. Consequently, scalability is a major issue in designing efficient QoS routing algorithms, due to the high costs of the associated overheads. Moreover, inaccuracy and staleness of global state information is another problem that is caused by relatively long update intervals, which can significantly deteriorate routing performance. Localized QoS routing, where source nodes take routing decisions based solely on statistics collected locally, was proposed relatively recently as a viable alternative to global QoS routing. It has shown promising results in achieving good routing performance, while at the same time eliminating many scalability related problems. In localized QoS routing each source¿destination pair needs to determine a set of candidate paths from which a path will be selected to route incoming flows. The goal of this thesis is to enhance the scalability of QoS routing by investigating and developing new models and algorithms based on the localized QoS routing approach. For this thesis, we have extensively studied the localized QoS routing approach and demonstrated that it can achieve a higher routing performance with lower overheads than global QoS routing schemes. Existing localized routing algorithms, Proportional Sticky Routing (PSR) and Credit-Based Routing (CBR), use the blocking probability of candidate paths as the criterion for selecting routing paths based on either flow proportions or a crediting mechanism, respectively. Routing based on the blocking probability of candidate paths may not always reflect the most accurate state of the network. This has motivated the search for alternative localized routing algorithms and to this end we have made the following contributions. First, three localized bandwidth-constrained QoS routing algorithms have been proposed, two are based on a source routing strategy and the third is based on a distributed routing strategy. All algorithms utilize the quality of links rather than the quality of paths in order to make routing decisions. Second, a dynamic precautionary mechanism was used with the proposed algorithms to prevent candidate paths from reaching critical quality levels. Third, a localized delay-constrained QoS routing algorithm was proposed to provide routing with an end-to-end delay guarantee. We compared the performance of the proposed localized QoS routing algorithms with other localized and global QoS routing algorithms under different network topologies and different traffic conditions. Simulation results show that the proposed algorithms outperform the other algorithms in terms of routing performance, resource balancing and have superior computational complexity and scalability features. / Umm AlQura University, Saudi Arabia

The growing demand on the variety of internet applications requires management of large scale networks by efficient Quality of Service (QoS) routing, which considerably contributes to the QoS architecture. The biggest contemporary drawback in the maintenance and distribution of the global state is the increase in communication overheads. Unbalancing in the network, due to the frequent use of the links assigned to the shortest path retaining most of the network loads is regarded as a major problem for best effort service. Localised QoS routing, where the source nodes use statistics collected locally, is already described in contemporary sources as more advantageous. Scalability, however, is still one of the main concerns of existing localised QoS routing algorithms. The main aim of this thesis is to present and validate new localised algorithms in order to develop the scalability of QoS routing. Existing localised routing, Credit Based Routing (CBR) and Proportional Sticky Routing (PSR), use the blocking probability as a factor in selecting the routing paths and work with either credit or flow proportion respectively, which makes impossible having up-to-date information. Therefore our proposed Highest Minimum Bandwidth (HMB) and Highest Average Bottleneck Bandwidth History (HABBH) algorithms utilise bandwidth as the direct QoS criterion to select routing paths. We introduce an Integrated Delay Based Routing and Admission Control mechanism. Using this technique Minimum Total Delay (MTD), Low Fraction Failure (LFF) and Low Path Failure (LPF) were compared against the global QoS routing scheme, Dijkstra, and localised High Path Credit (HPC) scheme and showed superior performance. The simulation with the non-uniformly distributed traffic reduced blocking probability of the proposed algorithms. Therefore, we advocate the algorithms presented in the thesis, as a scalable approach to control large networks. We strongly suggest that bandwidth and mean delay are feasible QoS constraints to select optimal paths by locally collected information. We have demonstrated that a few good candidate paths can be selected to balance the load in the network and minimise communication overhead by applying the disjoint paths method, recalculation of candidate paths set and dynamic paths selection method. Thus, localised QoS routing can be used as a load balancing tool in order to improve the network resource utilization. A delay and bandwidth combination is one of the future prospects of our work, and the positive results presented in the thesis suggest that further development of a distributed approach in candidate paths selection may enhance the proposed localised algorithms. / Umm AlQura University in Mecca

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