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Network coding is an emerging technique in communication networks, where the intennediate nodes are allowed to combine (code) the data received from different incoming links if necessary. The thesis investigates a nwnber of routing problems for network coding based multicast (NCM). which belong to combinatorial optimization problems (COPs). Evolutionary algorithms (EAs) are used to srudy the problems. The work of the thesis are described below. We propose three EAs for the network coding resource minimization (NCRM) problem where the objective is to minimize the number of coding operations while meeting the data rate requirement based on NCM. The three EAs are population based incremental learning (PBIL), compact genetic algorithm (cGA) and path-oriented encoding EA (PEA), all specially developed for tackling the NCRM problem. Ta support real-time multimedia applications, we for the first time extend the NCRM problem by introducing the maximum transmission delay into the problem as a constraint, which is called the delay constrained NCRM problem. Benchmark datasets are created based on the datasels for the NCRM problem. Three EAs originally used for the NCRM problem are adapted for the delay constrained NCRM ptoblem, including GAs and PBIL. To study the conflicting interests of service providers and network users, we for the first time fonnulate a multi-objective NCM routing problem considering two objectives, cost and delay. The cost is the summation of the coding cost and link cost incurred in the NCM. The delay is the maximum transmission delay of paths in the NCM. This problem is referred to as the cost-delay bi-objective optimization (CDBO) problem. Benchmark datasets for the delay constrained NCRM problem are used to generate the datasets for the CDBO problem. Elitist nondominated sorting GA (NSGA-II) is adapted for the CDBO problem.

Orthogonal frequency division multiplexing (OFDM) is the transmission scheme of choice for a number of communication systems and is likely to continue to be so for several future high-speed wireless networks. The biggest attractions of such technique are its high spectrum efficiency and resistance to multipath interference.

No description available.

The emergence of point-to-multipoint applications with Quality of Service (QoS) requirements in the Internet has prompted research towards the deployment of multicast communications in Differentiated Services (DiffServ) environments. However, despite many past research efforts, global availability of IP multicast is still a pie in the sky for Internet users, let alone applications with QoS guarantees. One of the key factors that hamper associated progress is scalability, in terms of various types of states associated with routing and signaling in both multicast and QoS. In this thesis we aim at a scalable architectural design of multicast service provisioning for end users with heterogeneous QoS requirements, targeted to the DiffServ environment. Our architecture consists of three planes: management, control and data plane. First of all, we design and evaluate the Offline Multicast Traffic Engineering (OMTE) building block in the management plane for QoS aware multicast service dimensioning. The main novelty of this scheme is that we shift away from the commonly used Multi-Protocol Label Switching (MPLS) based traffic engineering, and address the bandwidth constrained IP multicast TE directly based on link state routing protocols. With this approach, end-to-end performance can be achieved without MPLS explicit routing that potentially suffers from scalability problems in terms of Label Switching Path (LSP) maintenance and is relatively expensive to deploy. In the control plane, we propose two different paradigms. QoS aware Source Specific Multicast (QSSM) is designed for dedicated multicast delivery tree construction in different QoS classes, while another overlay scheme, known as Differentiated QoS Multicast (DQM), attempts to build a single hybrid tree that exhibits heterogeneous QoS channels within the network. In both approaches, multicast group addresses are used to encode QoS class information, and the associated benefit is reflected in scalability and backwards compatibility; neither underlying multicast protocols nor existing routers need any extension for carrying and maintaining QoS states within the network. Finally, envisaging the importance of protecting dimensioned resources from Denial-of-Service (DoS) attacks from malicious hosts, we propose the Multicast Sender Access Control (MSAC) mechanism, which is indispensable in multicast security, but still lacks significant attention from the research community. We focus on bi-directional multicast trees, which is the most vulnerable routing paradigm to DoS attacks. Both intra- and inter-domain control mechanisms are addressed with scalability considerations in mind.

One of the main problems concerning high-performance communications networks is the unavoidable congestion in network nodes. Network traffic is normally characterised as "bursty", which may use up network resources during peak periods. As a consequence end-user applications are subject to end-to-end delays and disruptions. Simultaneous transmission of packets on a finite bandwidth channel might result in contentions, where one or more packets are refrained from entering the transmission channel resulting in packet losses. Hence, the motivations of this thesis are two-fold: investigation and evaluation of switch architectures with electronic and optical buffers, and the development and evaluation of an improved dynamic threshold policy for shared memory switch architecture. In this work, switch architectures based on modular designs are evaluated, with simulation results showing that modular switch structures, i.e. multistage interconnection networks with optical delay line buffers, offer packet loss rate, throughput and average delay time similar to their electronic counterparts. Such optical architectures emulate prime features of shared memory switch architecture under general traffic conditions. Although the shared memory switch architecture is superior to other buffering approaches, but its performance is inadequate under imbalanced input traffic. Here its limiting features are investigated by means of numerical analysis. Different buffer management schemes, namely static thresholds, dynamic thresholds, pre-emptive, adaptive control, are investigated by using the Markov simulation model. An improved dynamic buffer management policy, decay function threshold (DFT) policy, is proposed and it is compared with the dynamic thresholds (DT), partial sharing partial partitioning (PSPP) and dynamic queue thresholds (DQT) buffer management policies by using bursty traffic source models, such as interrupted Poisson process (IPP), by means of simulations. Simulation results show that proposed policy is as good as well-known dynamic thresholds policy in the presence of best-effort traffic and offers improved packet loss performance when multicast traffic is considered. An integration framework for dynamic buffer management and bandwidth scheduling is also presented in this study. This framework employs loosely coupled buffer management and scheduling (weighted round robin, weighted fair queueing etc.) providing support for quality of service traffic. Conducted tests show that this framework matches the best-effort packet loss performance of dynamic thresholds policy.

La forte urbanisation dont le monde est témoin exige une meilleure gestion des villes. Cette gestion améliorée passe par la surveillance et la maintenance des équipements et infrastructures urbaines afin d'assurer plus de sécurité et bien-être aux habitants. Un rôle clé a donc été confié aux TIC à travers les concepts de l'IoT et des Villes Intelligentes. Cette thèse se positionne dans ce contexte et propose l'Identification par Radio Fréquence (RFID) en complément des techniques déjà utilisées. L'adoption de la RFID à grande échelle pour les centres urbains nécessite cependant de résoudre deux principaux problèmes : les collisions de lecture et la collecte et remontée des données. A travers les travaux menés dans cette thèse, nous avons d'abord cherché à identifier les solutions déjà proposées dans la littérature pour réduire les collisions. Sur la base de cette étude, nous avons proposé deux algorithmes distribués d'anticollision de lecture DEFAR et CORA. Ils permettent d'assurer un débit de lecture important en maintenant un taux de collisions et une latence de couverture faible comparés aux solutions de la littérature. Par la suite, nous avons proposé DACAR, un algorithme distribué de collecte des données issues des lecteurs RFID de manière multi-sauts. Il s'adapte en fonction du protocole d'anticollision utilisé et de la position des lecteurs déployés pour fournir un ratio de délivrance des paquets fiable et un faible délai de bout-en-bout. Une version améliorée est ultérieurement proposée pour la priorisation des données et offrir des chemins différents plus appropriés à l'aide d'une combinaison de différents paramètres grâce à la logique floue. / The strong urbanization witnessed by the world requires better management of cities. This improved management involves the monitoring and maintenance of urban infrastructure and equipment to ensure greater safety and well-being for residents. A key role has therefore been given to ICTs through the concepts of IoT and Smart Cities. This thesis is positioned in this context and proposes the Radio Frequency Identification (RFID) in addition to the techniques already in use. The adoption of large-scale RFID for urban centers, however, needs to address two main issues: reading collisions and data collection and reporting. Through the work carried out in this thesis, we first sought to identify the solutions already proposed in the literature to reduce collisions. Based on this study, we proposed two distributed anti-collision algorithms DEFAR and CORA. They ensure a high read throughput by maintaining a low collapse rate and latency compared to literature solutions. Subsequently, we proposed DACAR, a distributed algorithm for collecting data from RFID readers in a multi-hop manner. It adapts according to the anti-collision protocol used and the position of deployed drives to provide a reliable packet delivery ratio and low end-to-end delay. An improved version is later proposed for the prioritization of data and to offer more suitable different paths using a combination of different parameters through fuzzy logic.

Multicast applications have been a topic of intense research and development efforts over the past couple of years. Both the Internet Engineering (IETF) and International Telecommunication Union (ITU) have been heavily involved in providing quality of service to support multicast application requirements. Multicast applications have varying performance requirements; therefore it is necessary to design a framework that serves to guarantee quality of services. However the existing best effort services cannot provide the guaranteed service level required by multicast applications. Two solutions have already been proposed to overcome this problem. The first solution proposed the tree-based functionality approach in the multicast transport protocol providing reliability and scalability between a sender and a group of receivers. The other solution has proposed end-to-end quality of service (QoS) over the network environment using interoperation of Integrated services (IntServ) and Differentiated services (DiffServ) principles. Both QoS architectures, Integrated and Differentiated services, have their own advantages and disadvantages. With the interoperation of both architectures, it might be possible to build a scalable system, which would provide predictable services. This framework has to be supported by a multicast transport protocol to provide reliability and scalability over the nodes. The aim of this research is to develop a framework to provide reliably and scalability on nodes (tree-functionality) along with the end-to-end resources, dynamic admission control and scalability over the network (interoperation of IntServ and DiffServ) for multicast applications. The "Enhanced Communication Transport Protocol" (ECTP) transport protocol was chosen for this research. ECTP transport protocol is a multicast transport protocol with tree-based functionality to support multicast applications. ECTP transport protocol is also able to provide QoS management functionality established by Integrated or/and Differentiated services to support multicast application. With the QoS management functionality, ECTP transport protocol could provide reliability and scalability (over nodes) along with end-to-end resource, dynamic admission control and scalability over the network for multicast applications. This research is focused on the further enhancement and implementation of an ECTP transport protocol, QoS management specification. Two models have been proposed to enable ECTP transport protocol with QoS management functionality established by the IntServ or/and DiffServ principles. Model (I) enables ECTP transport protocol to negotiate end-to-end resource reservation using the standard RSVP (IntServ) signalling protocol. Model (II) enables the ECTP transport protocol to negotiate end-to-end resource reservation using the standard and aggregated RSVP (IntServ and DiffServ) signalling protocol. The "Optimized Network Engineering Tool 8.1" (OPNET) has been used in this research to implement and investigate the ECTP specifications. OPNET simulator provides a comprehensive development environment for modelling and performance of communications networks. The investigation consists of three case studies. The simulation results have proved that ECTP transport protocol with the tree-based functionality and the QoS management provided by IntServ and DiffServ interoperation produces the best performance for the traffic delay parameter over voice applications.