Future spacecrafts will require more computational and processing power to keep up with the growing demand in requirements and complexity. ScOSA is the next generation on-board computer developed by the German Aerospace Centre (DLR). The main motivation behind ScOSA is to replace the conventional on-board computer with distributed and reconfigurable computing nodes which provides higher performance, reliability, availability and stability by using a combination of the COTS components and reliable computing processors that are space qualified. In the current ScOSA system reconfiguration and routing of data between nodes are based on a static decision graph. SpaceWire protocol is used to communicate between nodes to provide reliability. The focus of the thesis is to design and implement a dynamic routing protocol for ScOSA which can be used in future for not only communicating between the nodes but also for reconfiguration. SpaceWire IPC is a customized protocol developed by DLR to provide communication between the nodes in a distributed network and to support monitoring, management and reconfiguration services. The dynamic routing protocol proposed in this thesis is primarily derived from the monitoring mechanism used in the SpaceWire IPC. PULL type monitoring mechanism is modelled and simulated using OMNeT++. The results obtained provide a qualitative outlook of the dynamic routing protocol implemented.

Recent disasters, including the 9/11 terrorist attacks, Hurricane Katrina, the London subway bombings, and the California wildfires, have all highlighted the limitations of current mobile communication systems for public safety first responders. First, in a point-to-point configuration, legacy radio systems used by first responders from differing agencies are often made by competing manufacturers and may use incompatible waveforms or channels. In addition, first responder radio systems, which may be licensed and programmed to operate in frequency bands allocated within their home jurisdiction, may be neither licensed nor available in forward-deployed disaster response locations, resulting in an operational scarcity of usable frequencies. To address these problems, first responders need smart radio solutions which can bridge these disparate legacy radio systems together, can incorporate new smart radio solutions, or can replace these existing aging radios. These smart radios need to quickly find each other and adhere to spectrum usage and access policies. Second, in an infrastructure configuration, legacy radio systems may not operate at all if the existing communications backbone has been destroyed by the disaster event. A communication system which can provide a new, temporary infrastructure or can extend an existing infrastructure into a shaded region is needed. Smart radio nodes that make up the public safety infrastructure again must be able to find each other, adhere to spectrum usage policies, and provide access to other smart radios and legacy public safety radios within their coverage area. This work addresses these communications problems in the following ways. First, it applies cognitive radio technology to develop a smart radio system capable of rapidly adapting itself so it can communicate with existing legacy radio systems or other smart radios using a variety of standard and customized waveforms. These smart radios can also assemble themselves into an ad-hoc network capable of providing a temporary communications backbone within the disaster area, or a network extension to a shaded communications area. Second, this work analyzes and characterizes a series of rendezvous protocols which enable the smart radios to rapidly find each other within a particular coverage area. Third, this work develops a spectrum sharing protocol that enables the smart radios to adhere to spectral policies by sharing spectrum with other primary users of the band. Fourth, the performance of the smart radio architecture, as well as the performance of the rendezvous and spectrum sharing protocols, is evaluated on a smart radio network testbed, which has been assembled in a laboratory setting. Results are compared, when applicable, to existing radio systems and protocols. Finally, this work concludes by briefly discussing how the smart radio technologies developed in this dissertation could be combined to form a public safety communications architecture, applicable to the FCC's stated intent for the 700 MHz Band. In the future, this work will be extended to applications outside of the public safety community, specifically, to communications problems faced by warfighters in the military. / Ph. D.

Modéliser et simuler (M&S) un système cyber-physique (SCP) peut nécessiter de représenter des éléments provenant de trois domaines d'expertise à la fois : systèmes physiques, systèmes d'informations et réseaux de communication (IP). Le simulateur universel disposant de toutes les compétences nécessaires n'existant pas, il est possible de regrouper des modèles issus des différentes communautés, à l'aide d'un multi-modèle. Les défis sont alors 1) intégrer toute l'hétérogénéité du multi-modèle (formalismes, représentations, implémentations), 2) intégrer des modèles IP de façon à ce qu'ils soient en capacité de représenter le transport de données applicatives produites par des modèles externes et 3) les intégrer de façon à ce qu'ils puissent se compléter, pour représenter ensemble les réseaux IP parfois hétérogènes d'un SCP. Pour parvenir à répondre à ces défis, nous nous inscrivons dans la continuité des travaux de M&S autour de MECSYCO, une plateforme de co-simulation basée sur la notion de wrapping DEVS. Nous proposons de définir un cadre général pour réussir à wrapper en DEVS des modèles IP, avec 1) une structuration des différents niveaux de problèmes pour l'intégration de modèles IP dans une co-simulation (délimitation des objectifs et contraintes du wrapping), et 2) une proposition de stratégie de wrapping DEVS de modèles IP et leurs simulateurs. Nous évaluerons notre approche à travers la démonstration de l'intégration de deux simulateurs IP populaires, et d'exemples concrets de M&S de SCP (avec notamment une interconnexion de modèles entre NS-3 et OMNeT++/INET, et une application industrielle utilisée par EDF R&D) / Modeling and simulation (M&S) of cyber-physical systems (CPS) can require representing components from three expertise fields: physics, information systems, and communication networks (IP). There is no universal simulator with all of the required skills, but we can gather and interconnect models provided by the communities, with a multi-model. The challenges are 1) integrating all heterogeneities in a multi-model (formalisms, representations, implementations), 2) integrating IP models in a way enabling them to represent the transport of application data produced by external models, and 3) integrating IP models in a way enabling them to complete each other, to be able to represent CPS heterogeneous IP networks. In order to meet these challenges, we relied our solution on the works around MECSYCO, a co-simulation platform based on the DEVS wrapping principle. We propose to define a comprehensive framework enabling to achieve DEVS wrapping of IP models, with 1) a structuration of different issue levels when integrating IP models in a co-simulation (goals and constraints of the wrapping) and 2) a proposition of a DEVS wrapping strategy for IP models and their simulators. We propose some evaluations of our approach, through the integration of two popular IP simulators, and concrete examples of CPS M&S (inter alia, with an example of a models interconnection between NS-3 and OMNeT++/INET, and an industrial application used by EDF R&D)

Approved for public release, distribution is unlimited / Converging voice and data networks has the potential to save money and is the main reason Voice over Internet Protocol (VoIP) is quickly becoming mainstream in corporate America. The potential VoIP offers to more efficiently utilize the limited connectivity available to ships at sea makes it an attractive option for the Navy. This thesis investigates the usefulness of VoIP for the communications needs of a unit level ship. This investigation begins with a review of what VoIP is and then examines the ship to shore connectivity for a typical unit level ship. An OMNeT++ model was developed and used to examine the issues that affect implementing VoIP over this type of link and the results are presented. / Lieutenant Commander, United States Navy

Approved for public release; distribution in unlimited. / As the popularity of Internet soars, the content on the Internet is increasingly accessed by mobile devices that are usually small in form factor and limited in resources, in terms of processing capability, bandwidth and battery power. With the changing environment, content providers must serve a large number of access devices with different profiles, while the users have access to a large number of services with different content types. A key challenge in such an environment is how to enable the best possible fit between content and capabilities of a specific access device type. The goal of this thesis research is to explore on the concept of a device-aware network (DAN) that can provide the infrastructure support for device-content compatibility matching to avoid the unnecessary wastage of network and device resources that happens in current device-ignorant networks. A more efficient architecture is proposed which encapsulates device profile information in transmitting packets and incorporates content repurposing functionality in existing network entities, such as routers along the data path. Simulation models are developed to statistically evaluate the performance of the proposed architecture in comparison to existing content repurposing frameworks. The results demonstrated the feasibility and suitability of the architecture, with improvement in network bandwidth conservation. / Civilian, Singapore Defence Science and Technology Agency

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.

Sensor technologies are vital today in gathering information about certain environments and wireless sensor networks are getting more widespread use everyday. These networks are characterized by a number of sensor nodes deployed in the field for the observation of some phenomena. Due to the limited battery capacity in sensor nodes, energy efficiency is a major and challenging problem in such power-constrained networks. Some of the network design parameters have a direct impact on the network&rsquo / s lifetime. These parameters have to be chosen in such a way that the network use its energy resources efficiently. This thesis studies these parameters that should be selected according to certain trade offs with respect to the network&rsquo / s lifetime. In this work, these trade offs have been investigated and illustrated in detail in various combinations. To achieve this goal, a special simulation tool has been designed and implemented in this work that helps in analyzing the effects of the selected parameters on sensor network&rsquo / s lifetime. OMNeT++, a discrete event simulator, provides the framework for the sensor network simulator&rsquo / s development. Ultimately, results of extensive computational tests are presented, which may be helpful in guiding the sensor network designers in optimally selecting the network parameters for prolonged lifetime.

Multihoming and mobility protocols enable computing devices to stay always best connected (ABC) to the Internet in the heterogeneous wireless environment. The ABC concept affords users the ability to choose the best available access networks and devices that best suit their needs, at any given point in time. With the emergence of multi-interfaced terminals, a mobile node may connect to different access networks simultaneously through multiple interfaces. This is called multihoming, and it allows a user to enjoy the best access for each application as well as other benefits such as fault tolerance, ubiquitous access and load balancing. Also, while the mobile node is moving from one wireless network to another, mobility management is important in keeping the node’s communication active during handover events. Therefore, the heterogeneous wireless environment requires the associated management of both multihoming and mobility since the mobile hosts are mobile and multihomed at the same time. Consequently, the purpose of our research is to compare the prevailing multihoming and mobility management protocols and corresponding implementations in the IPv6 heterogeneous wireless environment, and to identify the suitable protocol framework that supports both multihoming and mobility. The research started out with the study of the prominent host-based multihoming and mobility management protocols and solutions in IPv6. It then proceeded with a comparative qualitative review of the identified multihoming and mobility protocols according to their mechanisms, modes of operation, benefits and drawbacks. From the qualitative review, we identified suitable protocols that showed better performance for management of mobility and/or multihoming. Moreover, this provided a basis for defining the relevant simulation metrics for our comparative quantitative simulation analysis. The quantitative analysis was carried out using simulations on the OMNeT++ software platform, with the objective of comparing the performance of the studied multihoming and mobility protocols. Simulation scenarios were designed for mobility and multihoming cases, implemented and run using pertinent simulation protocol models of OMNeT++. The performance evaluation was investigated in terms of handover latency and rehoming time for mobility and multihoming protocols respectively. The simulation survey focused on the following protocols:Mobile IPv6 (MIPv6), Multiple Care-of Address (MCoA), Host Identity Protocol (HIP) and Stream Control Transmission Protocol (SCTP). Both the qualitative analysis and the results from the simulation study have shown that HIP has the best performance for mobility and multihoming management. Accordingly, our research has identified HIP as the best suitable framework that supports both multihoming and mobility management in IPv6 heterogeneous network environment. In addition, this project has demonstrated that multihomed nodes with multiple addresses experience less impact on real-time communication in case network failures or mobile movements compared to single-homed nodes. / Charles Mugga: +256790506653, Dong Sun: +8615106959570

The diploma´s thesis is focussed on principles and characteristics of Powerline Communication. Powerline communication is a technology using powerlines for transmitting information. Its narrowband variant is developing in the field of remote data reading nowadays. There is a lot of solutions that need to be tested and simulated prior ro putting into practice. This thesis deals with preparing the OMNeT++ simulation enviroment for purposes of simulating the narrowband service PLC.

OMNeT++ is a discrete event, modular simulator often used for simulation of computer networks. The universal simulator can be extended by various packages, such as INET framework, which is used for simulation of devices and TCP/IP protocols. This thesis examines facilities of INET package in the routing that is dynamic routing protocols. Concretely, it aims at OSPF protocol for IPv6 networks (OSPFv3). The protocol is presented and its principles are interpreted. The work is designed to simulate the module OSPFv3 protocol and module is partially implemented.