The development and growth of the Internet during the past thirty years has led to demand for and development of Internet services everywhere and over every possible communications medium. This includes the medium of satellite communications. During those same three decades, the growth in use of satellite communications to provide a widely-available wireless communications infrastructure has led to the development of broadband satellite communications using satellite constellation networks. These two technological trends have intersected. Here, we examine networking and internetworking issues affecting satellite networking in complex satellite constellation networks, and determine what is needed in order to support services based on the TCP/IP suite well in satellite constellations. We analyse constellation network topology. Its movement and effects on end-to-end delays experienced by network traffic travelling across the constellation are examined in detail. Analysis of the impact of cross-seam links upon delays experienced by traffic across star constellations shows that the use of cross-seam links is worthwhile. We examine the effects of multi-path routing within the constellation upon TCP communication, and demonstrate the performance advantages of an intelligent flowbased approach to routing in the constellation network. The desirability of implementing IP routing functionality in the space segment of the constellation is shown. The use of IP routing, to enable good support for IP QoS and IP multicast, is shown to be possible. We present an approach to implementing IP multicast within the constellation, evaluating use of a core-based tree algorithm, and outline an architecture permitting IP routing of IP traffic in an ATM-based satellite constellation network, using MPLS. Finally, we present and demonstrate the advantages of a novel method of managing path delay between ground terminals across a rosette constellation with intersatellite links, by using controlled handover to manage surface diversity to provide classes of service to network traffic.

No description available.

No description available.

Network security risk analysis has received great attention within the scientific community, due to the current proliferation of network attacks and threats. Although, considerable effort has been placed on improving security best practices, insufficient effort has been expanded on seeking to understand the relationship between risk-related variables and objectives related to cost-effective network security decisions. This thesis seeks to improve the body of knowledge focusing on the trade-offs between financial costs and risk while analysing the impact an identified vulnerability may have on confidentiality, integrity and availability (CIA). Both security best practices and risk assessment methodologies have been extensively investigated to give a clear picture of the main limitations in the area of risk analysis. The work begins by analysing information visualisation techniques, which are used to build attack scenarios and identify additional threats and vulnerabilities. Special attention is paid to attack graphs, which have been used as a base to design a novel visualisation technique, referred to as an Onion Skin Layered Technique (OSLT), used to improve system knowledge as well as for threat identification. By analysing a list of threats and vulnerabilities during the first risk assessment stages, the work focuses on the development of a novel Risk Assessment and Optimisation Model (RAOM), which expands the knowledge of risk analysis by formulating a multi-objective optimisation problem, where objectives such as cost and risk are to be minimised. The optimisation routine is developed so as to accommodate conflicting objectives and to provide the human decision maker with an optimum solution set. The aim is to minimise the cost of security countermeasures without increasing the risk of a vulnerability being exploited by a threat and resulting in some impact on CIA. Due to the multi-objective nature of the problem a performance comparison between multi-objective Tabu Search (MOTS) Methods, Exhaustive Search and a multi-objective Genetic Algorithm (MOGA) has been also carried out. Finally, extensive experimentation has been carried out with both artificial and real world problem data (taken from the case study) to show that the method is capable of delivering solutions for real world problem data sets.

The introduction of building management systems in large buildings have improved the control of building services and provided energy savings. However, current building management systems are limited by the physical level of integration of the building's services and the lack of intelligence provided in the control algorithms. This thesis proposes a new approach to the design and operation of building management systems using rule-based artificial intelligence techniques. The main aim of is to manage the services in the building in a more co-ordinated and intelligent manner than is possible by conventional techniques. This approach also aims to reduce the operational cost of the building by automatically tuning the energy consumption in accordance with occupancy profile of the building. A rule-based design methodology is proposed for building management systems. The design adopts the integrated structure made possible by the introduction of a common communications network for building services. The 'intelligence' is coded in the form of rules in such a way that it is both independent of any specific building description and easy to facilitate subsequent modification and addition. This is achieved using an object-oriented approach and classifying the range of data available into defined classes. The rules are divided into two knowledge-bases which are concerned with the building's control and its facilities management respectively. A wide range of rule-based features are proposed to operate on this data structure and are classified in terms of the data classes on which they operate. The concepts presented in this thesis were evaluated using software simulations, mathematical analysis and some hardware implementation. The conclusions of this work are that a rule-based building management system could provide significant enhancements over existing systems in terms of energy savings and improvements for both the building's management staff and its occupants.

Thesis (M.Eng.(Electronic Engineering))--University of Pretoria, 2008. / Summary in English. Includes bibliographical references (leaves [92]-95).

Yes / Satellite communications represents a specialised area of telecommunications. While the development of satellite technology is relatively slow in comparison to wireless networks evolution, due to the need for high reliability, the services that satellites are able to offer are evolving at much the same pace as their terrestrial counterparts. It is within this context that the satellite communications network of excellence (SatNEx) has evolved its initiative, the aim being to serve the engineering community with the latest technological trends, while also providing a solid grounding in the fundamentals for those new to the subject area. / European Commission Framework Programme 6

International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, Nevada / NASA and the Air Force are increasing the number of hypersonic and access-to-space programs creating a growing requirement for flight test ranges over large regional areas. A principal challenge facing these extended test ranges is the ability to provide continuous vehicle communications by filling the gaps in coverage between fixed ground stations. Consequently, there is a need for mobile range systems that provide a multitude of communication services under varying circumstances. This paper discusses the functional design and systems capabilities, as well as the mission support criteria, concerning NASA’s Mobile Operations Facility (MOF). The MOF will be deployed to Dugway Proving Grounds (DPG), Utah, in support of the X-33 single-stage-to-orbit (SSTO) demonstrator.

Thesis (Ph. D.)--School of Computing and Engineering. University of Missouri--Kansas City, 2004. / "A dissertation in engineering and computer networking." Advisor: Ghulam Chaudhry. Typescript. Vita. Title from "catalog record" of the print edition Description based on contents viewed Feb. 22, 2006. Includes bibliographical references (leaves 135-157). Online version of the print edition.

Magister Scientiae - MSc / This thesis demonstrates that a situation-aware algorithm improves quality of service on small mesh networks running BATMAN-adv with some mobile nodes. BATMAN-adv is a proactive mesh routing protocol that counts beacons as a link quality metric. BATMAN-adv was modi ed to give more recently received beacons more weight, thereby calculating a more precise indication of the current state of a link that BATMAN-adv can use to forward packets. BATMAN-adv `original' was compared with a situation-aware version in two laboratory test beds with the same voice traffic profile on actual hardware with a realistic voice traffic profile; with controlled transmission rates and buffer sizes to simulate congestion. The second test bed included mesh potatoes, PCs and laptops as mobile nodes. BATMAN-adv achieved better jitter and packet loss than the situation-aware version in the initial, smaller test bed, and average throughput for both versions was almost identical. However, in the second slightly larger test bed, with additional mobile nodes, the situation-aware algorithm performed better than the original BATMAN-adv algorithm for all quality of service metrics, including throughput. Thus the thesis concludes that a situation-aware protocol offers a promising solution to address issues pertaining to mobility, congestion and scalability for voice traffic in mesh networks with mobile nodes. / South Africa