MPLS, the next-generation backbone architecture, can speed up packet forwarding via label switching. However, if the traversed LSPs (Label Switching Paths) are in congestion, traffic may encounter serious throughput degradation due to packet loss. This performance degradation may become worse and worse unless another forwarding LSP for these traffic flows are allocated. Moreover, in this Thesis, we propose a preemption mechanism for higher-priority flows to obtain necessary resources (the bandwidth of a LSP) by preempting low-priority traffic flows. In the multiple-flow preemption mechanism, several LSPs between Ingress router and Egress router are established to forward traffic flows. Some of these traffic flows are higher priority with stringent QoS requirements. If no satisfactory throughput can be met, Egress router would have to feedback average throughput values to Ingress router, which in turn decides how many lower-priority traffic flows should be preempted and moved to another LSP. Consequently, Ingress router has to send bandwidth reservation messages to reserve bandwidth just released by those lower-priority flows. After that, every core router can process these MPLS packets with specified traffic class to meet their QoS requirements. Finally, for the purpose of demonstration, we embed multiple flow preemption modules into MNS simulator and use it to run some experiments. Since in our scheme, it is not necessary to reserve bandwidth for higher-priority traffic flows in advance, the overall bandwidth utilization can be increased. Furthermore, the higher-priority flows can meet their QoS requirements by preempting the lower-priority flows whenever it is needed.

Because of the advancement of wireless networks, it is important to provide quality-of-service (QoS) guarantees as they are expected to support multimedia applications. In this paper we propose a new bandwidth reservation scheme based on the characteristic of the cell equipped with sector antenna. According to this information, the proposed scheme can predict the next location of each connection and precisely reserve bandwidth in appropriate neighboring cells, not all of its neighboring cells. Besides, the proposed scheme uses bandwidth borrowing mechanism to be our call admission control strategy. The combination of bandwidth reservation and bandwidth borrowing provides network users with QoS in terms of guaranteed bandwidth, call blocking and call dropping probabilities.

In this Thesis, we propose a Negotiable RSVP with Multiple Preemption for supporting dynamic bandwidth reservation. With the properties of negotiation and preemption, we can re-allocate bandwidth to effectively increase the probability of successful reservations of flows with higher priority. Different from RSVP, negotiable RSVP uses a priority mechanism with many parameters, such as upper-bound bandwidth and upper-bound priority. Negotiable RSVP transmits these parameters by sending Resv Messages such that every RSVP flow possesses individual priority levels. When the available bandwidth is not enough, the arriving new flows can negotiate with the existing reserved flows that have lower priorities. We then estimate the sum of the available bandwidth and the preemptive bandwidth from the reserved flows. If the sum satisfies the lower-bound bandwidth of the arriving new flow, the reservation is successful. At the best case, if the sum can meet its high-bound bandwidth, the system can reserve the high-bound bandwidth for the flow. However, if the sum is lower than its low-bound bandwidth, it will be rejected. To demonstrate the efficiency and feasibility of negotiable RSVP, we build two simulation models, RSVP and Negotiable RSVP, respectively, and compare their simulation results. We have shown that negotiable RSVP can perform better than RSVP in many ways. For example, the probability of successful reservation and the number of reserved flows are significantly increased. We also implement the negotiable RSVP on FreeBSD platform, and measure the percentages of improvements through various experiments.

Because there has been a rapid development in wireless networks, it is important to provide quality-of-service (QoS) guarantees as they are expected to support multimedia applications. In this paper we propose a new bandwidth reservation scheme based on the characteristic of the cell equipped with sector antenna and 2-tier cell structure. According to this information, the proposed scheme can predict the next location of each connection and precisely reserve bandwidth in appropriate neighboring cells, not all of its neighboring cells. In addition, the proposed scheme incorporates bandwidth borrowing mechanism into call admission control strategy. The combination of bandwidth reservation and bandwidth borrowing provides network users with QoS in terms of guaranteed bandwidth, call blocking and call dropping probabilities.

Video traffic constitutes a major part of the Internet traffic nowadays. Yet most video delivery services remain best-effort, relying on server bandwidth over-provisioning to guarantee Quality of Service (QoS). Cloud computing is changing the way that video services are offered, enabling elastic and efficient resource allocation through auto-scaling. In this thesis, we propose a new framework of cloud workload management for multimedia delivery services, incorporating demand forecast, predictive resource allocation and quality assurance, as well as resource pricing as inter-dependent components. Based on the trace analysis of a production Video-on-Demand (VoD) system, we propose time-series techniques to predict video bandwidth demand from online monitoring, and determine bandwidth reservations from multiple data centers and the related load direction policy. We further study how such quality-guaranteed cloud services should be priced, in both a game theoretical model and an optimization model.Particularly, when multiple video providers coexist to use cloud resources, we use pricing to control resource allocation in order to maximize the aggregate network utility, which is a standard network utility maximization (NUM) problem with coupled objectives. We propose a novel class of iterative distributed solutions to such problems with a simple economic interpretation of pricing. The method proves to be more efficient than the conventional approach of dual decomposition and gradient methods for large-scale systems, both in theory and in trace-driven simulations.

Video traffic constitutes a major part of the Internet traffic nowadays. Yet most video delivery services remain best-effort, relying on server bandwidth over-provisioning to guarantee Quality of Service (QoS). Cloud computing is changing the way that video services are offered, enabling elastic and efficient resource allocation through auto-scaling. In this thesis, we propose a new framework of cloud workload management for multimedia delivery services, incorporating demand forecast, predictive resource allocation and quality assurance, as well as resource pricing as inter-dependent components. Based on the trace analysis of a production Video-on-Demand (VoD) system, we propose time-series techniques to predict video bandwidth demand from online monitoring, and determine bandwidth reservations from multiple data centers and the related load direction policy. We further study how such quality-guaranteed cloud services should be priced, in both a game theoretical model and an optimization model.Particularly, when multiple video providers coexist to use cloud resources, we use pricing to control resource allocation in order to maximize the aggregate network utility, which is a standard network utility maximization (NUM) problem with coupled objectives. We propose a novel class of iterative distributed solutions to such problems with a simple economic interpretation of pricing. The method proves to be more efficient than the conventional approach of dual decomposition and gradient methods for large-scale systems, both in theory and in trace-driven simulations.

Many next-generation e-science applications require fast and reliable transfer of large volumes of data, now frequently termed as ``big data", with guaranteed performance, which is typically enabled by the bandwidth reservation service in high-performance networks (HPNs). Users normally specify the properties and requirements of their data transfers in the bandwidth reservation requests (BRRs), and want to make bandwidth reservations on the HPNs to satisfy the requirements of their data transfers. The challenges of the bandwidth reservation arise from the requirements desired by both the users and the bandwidth reservation service providers of the HPNs. We focus on two important bandwidth reservation problems formulated from the combinations of the requirements from both users and the bandwidth reservation service providers of the HPNs: (i) Problem of scheduling all BRRs in one batch while achieving their best average data transfer earliest completion time and shortest duration, and (ii) Problem of scheduling two generic types of BRRs concerning data transfer reliability with different objectives and constraints in unreliable HPNs that are subject to node and link failures. We prove the two subproblems of the first problem are NP-complete problems, and fast and efficient heuristic algorithms are proposed. While the two subproblems of the second problem can be optimally solved in polynomial time. The corresponding optimal algorithms and proofs are given. We conduct extensive simulations to compare the performance of the proposed heuristic and optimal algorithms with naive scheduling algorithms and the algorithms currently used in production network in various performance metrics. The performance superiority of the proposed heuristic and optimal algorithms is verified.

Mobile handset manufacturers have begun to include wireless LAN (WLAN) interfaces in their cellular handsets. This allows users to access WLAN networks when they are available and to revert to conventional cellular communications otherwise. In this way the handset can dynamically use the "best" available network, by switching connections between the two network interfaces. This switching is referred to as a vertical handoff (VHO). When handling real-time connections, handsets must be capable of performing a seamless vertical handoff. This occurs when the interface switching does not disrupt the quality of service requirements of the active connections. Vertical handoffs are generally time consuming, and this delay creates a difficult problem since WLAN coverage can be lost very abruptly. In this thesis, we propose and investigate several methods of mitigating this problem. A solution based on using a Vertical Handoff Support Node (VHSN) is proposed. When the WLAN link is lost, the VHSN is able to quickly redirect packets through the local cellular base-station during the time that handoff is taking place. This approach can eliminate VHO link loss. It is shown that the act of WLAN-to-cellular handoff can result in a severe bandwidth deficit problem on the WLAN. A novel bandwidth reservation and securing mechanism is proposed which overcomes this problem and performs significantly better than schemes based on modified versions of the static guard channel scheme used in cellular networks. The work is characterized by simulation and analytic models which investigate the key performance aspects of this type of system. / Thesis / Doctor of Philosophy (PhD)

<p> Telemedicine traffic transmission over wireless cellular networks has gained in importance during the last few years. Most of the current research in the field has focused on software and hardware implementations for telemedicine transmission, without discussing the case of simultaneous transmission of both urgent telemedicine traffic and regular multimedia traffic over the network.</p> <p> Due to the fact that telemedicine traffic carries critical information regarding the patients' condition, it is vitally important that this traffic has highest transmission priority in comparison to all other types of traffic in the cellular network. However, the need for expedited and correct transmission of telemedicine traffic calls for a guaranteed bandwidth to telemedicine users. This creates a tradeoff between the satisfaction of the very strict Quality of Service (QoS) requirements of telemedicine traffic and the loss of the guaranteed bandwidth in the numerous cases when it is left unused, due to the infrequent nature of telemedicine traffic. This waste of the bandwidth may lead to a lack of sufficient bandwidth for regular traffic, hence degrading its QoS.</p> <p> To resolve this complex problem, in this thesis, we propose a) an adaptive bandwidth reservation scheme based on road map information and on users' mobility, and b) a fair scheduling scheme for video traffic transmission over wireless cellular networks. The proposed combination of the two schemes, which is evaluated over a hexagonal cellular structure, is shown to achieve high channel bandwidth utilization while offering full priority to telemedicine traffic.</p> / Thesis / Master of Applied Science (MASc)

L’émergence de nouvelles applications et de nouveaux services (tels que les applications multimédias, la voix-sur-IP, la télévision-sur-IP, la vidéo-sur-demande, etc.) et le besoin croissant de mobilité des utilisateurs entrainent une demande de bande passante de plus en plus croissante et une difficulté dans sa gestion dans les réseaux cellulaires sans fil (WCNs), causant une dégradation de la qualité de service. Ainsi, dans cette thèse, nous nous intéressons à la gestion des ressources, plus précisément à la bande passante, dans les WCNs. Dans une première partie de la thèse, nous nous concentrons sur la prédiction de la mobilité des utilisateurs des WCNs. Dans ce contexte, nous proposons un modèle de prédiction de la mobilité, relativement précis qui permet de prédire la destination finale ou intermédiaire et, par la suite, les chemins des utilisateurs mobiles vers leur destination prédite. Ce modèle se base sur : (a) les habitudes de l’utilisateur en terme de déplacements (filtrées selon le type de jour et le moment de la journée) ; (b) le déplacement courant de l’utilisateur ; (c) la connaissance de l’utilisateur ; (d) la direction vers une destination estimée ; et (e) la structure spatiale de la zone de déplacement. Les résultats de simulation montrent que ce modèle donne une précision largement meilleure aux approches existantes. Dans la deuxième partie de cette thèse, nous nous intéressons au contrôle d’admission et à la gestion de la bande passante dans les WCNs. En effet, nous proposons une approche de gestion de la bande passante comprenant : (1) une approche d’estimation du temps de transfert intercellulaire prenant en compte la densité de la zone de déplacement en terme d’utilisateurs, les caractéristiques de mobilité des utilisateurs et les feux tricolores ; (2) une approche d’estimation de la bande passante disponible à l’avance dans les cellules prenant en compte les exigences en bande passante et la durée de vie des sessions en cours ; et (3) une approche de réservation passive de bande passante dans les cellules qui seront visitées pour les sessions en cours et de contrôle d’admission des demandes de nouvelles sessions prenant en compte la mobilité des utilisateurs et le comportement des cellules. Les résultats de simulation indiquent que cette approche réduit largement les ruptures abruptes de sessions en cours, offre un taux de refus de nouvelles demandes de connexion acceptable et un taux élevé d’utilisation de la bande passante. Dans la troisième partie de la thèse, nous nous penchons sur la principale limite de la première et deuxième parties de la thèse, à savoir l’évolutivité (selon le nombre d’utilisateurs) et proposons une plateforme qui intègre des modèles de prédiction de mobilité avec des modèles de prédiction de la bande passante disponible. En effet, dans les deux parties précédentes de la thèse, les prédictions de la mobilité sont effectuées pour chaque utilisateur. Ainsi, pour rendre notre proposition de plateforme évolutive, nous proposons des modèles de prédiction de mobilité par groupe d’utilisateurs en nous basant sur : (a) les profils des utilisateurs (c’est-à-dire leur préférence en termes de caractéristiques de route) ; (b) l’état du trafic routier et le comportement des utilisateurs ; et (c) la structure spatiale de la zone de déplacement. Les résultats de simulation montrent que la plateforme proposée améliore la performance du réseau comparée aux plateformes existantes qui proposent des modèles de prédiction de la mobilité par groupe d’utilisateurs pour la réservation de bande passante. / The emergence of new applications and services (e.g., multimedia applications, voice over IP and IPTV) and the growing need for mobility of users cause more and more growth of bandwidth demand and a difficulty of its management in Wireless Cellular Networks (WCNs). In this thesis, we are interested in resources management, specifically the bandwidth, in WCNs. In the first part of the thesis, we study the user mobility prediction that is one of key to guarantee efficient management of available bandwidth. In this context, we propose a relatively accurate mobility prediction model that allows predicting final or intermediate destinations and subsequently mobility paths of mobile users to reach these predicted destinations. This model takes into account (a) user’s habits in terms of movements (filtered according to the type of day and the time of the day); (b) user's current movement; (c) user’s contextual knowledge; (d) direction from current location to estimated destination; and (e) spatial conceptual maps. Simulation results show that the proposed model provides good accuracy compared to existing models in the literature. In the second part of the thesis, we focus on call admission control and bandwidth management in WCNs. Indeed, we propose an efficient bandwidth utilization scheme that consists of three schemes: (1) handoff time estimation scheme that considers navigation zone density in term of users, users’ mobility characteristics and traffic light scheduling; (2) available bandwidth estimation scheme that estimates bandwidth available in the cells that considers required bandwidth and lifetime of ongoing sessions; and (3) passive bandwidth reservation scheme that passively reserves bandwidth in cells expected to be visited by ongoing sessions and call admission control scheme for new call requests that considers the behavior of an individual user and the behavior of cells. Simulation results show that the proposed scheme reduces considerably the handoff call dropping rate while maintaining acceptable new call blocking rate and provides high bandwidth utilization rate. In the third part of the thesis, we focus on the main limitation of the first and second part of the thesis which is the scalability (with the number of users) and propose a framework, together with schemes, that integrates mobility prediction models with bandwidth availability prediction models. Indeed, in the two first contributions of the thesis, mobility prediction schemes process individual user requests. Thus, to make the proposed framework scalable, we propose group-based mobility prediction schemes that predict mobility for a group of users (not only for a single user) based on users’ profiles (i.e., their preference in terms of road characteristics), state of road traffic and users behaviors on roads and spatial conceptual maps. Simulation results show that the proposed framework improves the network performance compared to existing schemes which propose aggregate mobility prediction bandwidth reservation models.