Doctor of Philosophy

dissertationPortable electronic devices will be limited to available energy of existing battery chemistries for the foreseeable future. However, system-on-chips (SoCs) used in these devices are under a demand to offer more functionality and increased battery life. A difficult problem in SoC design is providing energy-efficient communication between its components while maintaining the required performance. This dissertation introduces a novel energy-efficient network-on-chip (NoC) communication architecture. A NoC is used within complex SoCs due it its superior performance, energy usage, modularity, and scalability over traditional bus and point-to-point methods of connecting SoC components. This is the first academic research that combines asynchronous NoC circuits, a focus on energy-efficient design, and a software framework to customize a NoC for a particular SoC. Its key contribution is demonstrating that a simple, asynchronous NoC concept is a good match for low-power devices, and is a fruitful area for additional investigation. The proposed NoC is energy-efficient in several ways: simple switch and arbitration logic, low port radix, latch-based router buffering, a topology with the minimum number of 3-port routers, and the asynchronous advantages of zero dynamic power consumption while idle and the lack of a clock tree. The tool framework developed for this work uses novel methods to optimize the topology and router oorplan based on simulated annealing and force-directed movement. It studies link pipelining techniques that yield improved throughput in an energy-efficient manner. A simulator is automatically generated for each customized NoC, and its traffic generators use a self-similar message distribution, as opposed to Poisson, to better match application behavior. Compared to a conventional synchronous NoC, this design is superior by achieving comparable message latency with half the energy

Mitigating TCP Degradation over Intermittent Link Failures Using Intermediate Buffers

This thesis addresses the improvement of data transmission performance in a challenged network. It is well known that the popular Transmission Control Protocol degrades in environments where one or more of the links along the route is intermittently available. To avoid this degradation, this thesis proposes placing at least one node along the path of transmission to buffer and retransmit as needed to overcome the intermittent link. In the four-node, three-link testbed under particular conditions, file transmission time was reduced 20 fold in the case of an intermittent second link when the second node strategically buffers for retransmission opportunity

Performance analysis and application development of hybrid WiMAX-WiFi IP video surveillance systems

Traditional Closed Circuit Television (CCTV) analogue cameras installed in buildings and other areas of security interest necessitates the use of cable lines. However, analogue systems are limited by distance; and storing analogue data requires huge space or bandwidth. Wired systems are also prone to vandalism, they cannot be installed in a hostile terrain and in heritage sites, where cabling would distort original design. Currently, there is a paradigm shift towards wireless solutions (WiMAX, Wi-Fi, 3G, 4G) to complement and in some cases replace the wired system. A wireless solution of the Fourth-Generation Surveillance System (4GSS) has been proposed in this thesis. It is a hybrid WiMAX-WiFi video surveillance system. The performance analysis of the hybrid WiMAX-WiFi is compared with the conventional WiMAX surveillance models. The video surveillance models and the algorithm that exploit the advantages of both WiMAX and Wi-Fi for scenarios of fixed and mobile wireless cameras have been proposed, simulated and compared with the mathematical/analytical models. The hybrid WiMAX-WiFi video surveillance model has been extended to include a Wireless Mesh configuration on the Wi-Fi part, to improve the scalability and reliability. A performance analysis for hybrid WiMAX-WiFi system with an appropriate Mobility model has been considered for the case of mobile cameras. A security software application for mobile smartphones that sends surveillance images to either local or remote servers has been developed. The developed software has been tested, evaluated and deployed in low bandwidth Wi-Fi wireless network environments. WiMAX is a wireless metropolitan access network technology that provides broadband services to the connected customers. Major modules and units of WiMAX include the Customer Provided Equipment (CPE), the Access Service Network (ASN) which consist one or more Base Stations (BS) and the Connectivity Service Network (CSN). Various interfaces exist between each unit and module. WiMAX is based on the IEEE 802.16 family of standards. Wi-Fi, on the other hand, is a wireless access network operating in the local area network; and it is based on the IEEE 802.11 standards

Intelligent adaptive bandwidth provisioning for quality of service in umts core networks

Master'sMASTER OF ENGINEERIN

Estudio de la movilidad en redes de siguiente generación

El continuo avance de las redes de telecomunicaciones nos proporciona cada vez más facilidades en todos los ámbitos de nuestra vida. En este caso, nos hemos centrado en el estudio de la movilidad en Redes de Siguiente Generación. Una parte del presente proyecto se ha realizado en colaboración con Deutsche Telekom AG, durante una estancia de seis meses trabajando como colaboradora en sus laboratorios con emplazamiento en Berlín. El principal objetivo de este proyecto ha sido realizar un estudio sobre los diferentes estándares y tecnologías que facilitan la movilidad en Redes de Siguiente Generación. Por ello, en la primera parte se han estudiado los diferentes grupos de trabajo centrados en este aspecto, así como se ha recabado información sobre productos y soluciones disponibles en el mercado, para obtener una visión global de la situación actual. Como se puede comprobar más adelante, esta primera parte es la más extensa de todo el documento. Esto se debe a que es, probablemente, la parte más importante del trabajo, ya que contiene el estudio de los mecanismos que más tarde nos servirán para dar una solución teórica a los distintos escenarios que se plantean. En la segunda parte del proyecto, nos hemos centrado en desarrollar varios escenarios de interés en sistemas de Redes de Siguiente Generación y aportar, de forma posterior, posibles soluciones teóricas. Para finalizar, se han expuesto las conclusiones extraídas como resultado del trabajo y los aspectos que se podrán tratar sobre el mismo en un futuro próximo.Ingeniería de Telecomunicació

Analysis, design and experimental evaluation of connectivity management in heterogeneous wireless environments

Mención Internacional en el título de doctorThe future of network communications is mobile as many more users demand for ubiquitous connectivity. Wireless has become the primary access technology or even the only one, leading to an explosion in traffic demand. This challenges network providers to manage and configure new requirements without incrementing costs in the same amount. In addition to the growth in the use of mobile devices, there is a need to operate simultaneously different access technologies. As well, the great diversity of applications and the capabilities of mobile terminals makes possible for us to live in a hyper-connected world and offers new scenarios. This heterogeneity poses great challenges that need to be addressed to offer better performance and seamless experience to the final user. We need to orchestrate solutions to increase flexibility and empower interoperability. Connectivity management is handled from different angles. In the network stack, mobility is more easily handled by IP mobility protocols, since IP is the common layer between the different access technologies and the application diversity. From the end-user perspective, the connection manager is in charge of handling connectivity issues in mobile devices, but it is an unstandardized entity so its performance is heavily implementation-dependent. In this thesis we explore connectivity management from different angles. We study mobility protocols as they are part of our proposed solutions. In most of the cases we include an experimental evaluation of performance with 3G and IEEE 802.11 as the main technologies. We consider heterogeneous scenarios, with several access technologies where mobile devices have also several network interfaces. We evaluate how connectivity is handled as well as its influence in a handover. Based on the analysis of real traces from a cellular network, we confirm the suitability of more efficient mobility management. Moreover, we propose and evaluate three different solutions for providing mobility support in three different heterogeneous scenarios. We perform an experimental evaluation of a vehicular route optimization for network mobility, reporting on the challenges and lessons learned in such a complicated networking environment. We propose an architecture for supporting mobility and enhance handover in a passive optical network deployment. In addition, we design and deploy a mechanism for mobility management based on software-defined networking.Programa Oficial de Doctorado en Ingeniería TelemáticaPresidente: Arturo Azcorra Saloña.- Secretario: Ramón Agüero Calvo.- Vocal: Daniel Nunes Coruj

Smart Virtualization for Packet Forwarding in 5G and Beyond Communication Networks

This thesis was submitted for the award of Doctor of Philosophy and was awarded by Brunel University LondonIn this thesis, novel ideas have been proposed to tackle the delay and connection continuity, which are caused by different factors related to wired and wireless communication system networks. The vast majority, if we do not say all of these systems adopt packet switch schemes to transfer the data amongst network devices. Moreover, all these systems aim to deliver the data from the source to the destination according to particular Identifiers (IDs) of these devices. The most well-known IDs that are used to distinguish devices are IP address, MAC address, and Subscriber National Number. By virtualizing the servers of communication systems, new concepts of communication networks have emerged. For instance, a mobile operator’s core network function servers could be virtualized, installed, and run by Virtual Machines (VMs) to execute these functions. Also, routers, switches, firewalls, and other network devices could be virtualized by using SDN, NFV, and new- generation protocols such as OpenFlow to create a high performance of the virtualized communication network. From this point of view, we proposed novel concepts such as SVeNB which mimicked the functions of the base station and the core network of a mobile operator network. The SVeNB performance exceeded the C-RAN with 68% in user profiles treatment. Also, the SVeNB reduced the End-to-End delay to 62%. Other advantages of the virtualization are ease of separating the functions and control layer of the networks. This approach urged researchers to suggest a new communication network topologies and innovative designing of flexible and programmable routing protocols. As a result of these approaches, emerging the SDN networks to carry packet forwarding schemes on the communication networks. Based on the facts mentioned above, we designed a novel idea to generate a tag as a mobile node’s ID from E.164 standard numbering and MAC address to handle the packets inside the networks. The results showed that the packet loss rate decreased to 4% of that were lost during the handover delay time or while packets re-direction mechanism. At the same time, the MN could receive 96.4% of the data that was lost during the handover process. Mobility management is a vital issue in wireless communication, due to the necessity of changing the ID of the wireless attached Access Points (APs) by a moving target which connects to that APs. The biggest obstacle of mobility is that the addresses resolution should be made in real time. More difficulty is added when the motion of moving targets is very speedy, for example, such as High-Speed Trains. A novel proactive scheme has been presented by chapter 4 for directing the packet flows among the APs, with support of the trigger signal to activate layer 2 handover. By using the triggering signal, the performance of the suggested network surpassed the performance results that were not supported by the triggering signal. The average control delay time was reduced by nearly 45% and the retrieved data were roughly 90% of packet loss when adopting the triggering signal system.Ministry of Higher Education and Scientific Research (MOHESR) / Iraq, Iraqi Cultural Attach

Mobile Ad-Hoc Networks

Being infrastructure-less and without central administration control, wireless ad-hoc networking is playing a more and more important role in extending the coverage of traditional wireless infrastructure (cellular networks, wireless LAN, etc). This book includes state-of the-art techniques and solutions for wireless ad-hoc networks. It focuses on the following topics in ad-hoc networks: vehicular ad-hoc networks, security and caching, TCP in ad-hoc networks and emerging applications. It is targeted to provide network engineers and researchers with design guidelines for large scale wireless ad hoc networks