Spectrum control and iterative coding for high capacity multiband OFDM

The emergence of Multiband Orthogonal Frequency Division Modulation (MB-OFDM) as an ultra-wideband (UWB) technology injected new optimism in the market through realistic commercial implementation, while keeping promise of high data rates intact. However, it has also brought with it host of issues, some of which are addressed in this thesis. The thesis primarily focuses on the two issues of spectrum control and user capacity for the system currently proposed by the Multiband OFDM Alliance (MBOA). By showing that line spectra are still an issue for new modulation scheme (MB-OFDM), it proposes a mechanism of scrambling the data with an increased length linear feedback shift register (compared to the current proposal), a new set of seeds, and random phase reversion for the removal of line spectra. Following this, the thesis considers a technique for increasing the user capacity of the current MB-OFDM system to meet the needs of future wireless systems, through an adaptive multiuser synchronous coded transmission scheme. This involves real time iterative generation of user codes, which are generated over time and frequency leading to increased capacity. With the assumption of complete channel state information (CSI) at the receiver, an iterative MMSE algorithm is used which involves replacement of each users s signature with its normalized MMSE filter function allowing the overall Total Squared Correlation (TSC) of the system to decrease until the algorithm converges to a fixed set of signature vectors. This allows the system to be overloaded and user\u27s codes to be quasi-orthogonal. Simulation results show that for code of length nine (spread over three frequency bands and three time slots), ten users can be accommodated for a given QoS and with addition of single frequency sub-band which allows the code length to increase from nine to twelve (four frequency sub-bands and three time slots), fourteen users with nearly same QoS can be accommodated in the system. This communication is overlooked by a central controller with necessary functionalities to facilitate the process. The thesis essentially considers the uplink from transmitting devices to this central controller. Furthermore, analysis of this coded transmission in presence of interference is carried to display the robustness of this scheme through its adaptation by incorporating knowledge of existing Narrowband (NB) Interference for computing the codes. This allows operation of sub-band coexisting with NB interference without substantial degradation given reasonable interference energy (SIR=-l0dB and -5dB considered). Finally, the thesis looks at design implementation and convergence issues related to code vector generation whereby, use of Lanczos algorithm is considered for simpler design and faster convergence. The algorithm can be either used to simplify design implementation by providing simplified solution to Weiner Hopf equation (without requiring inverse of correlation matrix) over Krylov subspace or can be used to expedite convergence by updating the signature sequence with eigenvector corresponding to the least eigenvalue of the signature correlation matrix through reduced rank eigen subspace search

Flood dynamics, surface water retention and availability in the semiarid Cuvelai-Basin, southern Angola and northern Namibia

Located in the western part of the Cuvelai Basin, the Iishana system is a transboundary region covering parts of southern Angola and northern Namibia. Hydrologically, this region is characterized by a network of episodically water-bearing channels in which numerous pans are embedded. These pans, which fill up during the rainy season, form an important water resource for the rural population, especially for agricultural and domestic use. The Iishana system is one of the most densely populated areas in southwestern Africa, and this high population trend is increasing (NamStat 2013). To date, the majority of the population (80–90%) currently lives in rural areas. However, (small) cities are experiencing steady growth. The semi-arid climate in this area has distinct rainy and dry seasons and is characterized by high interannual variability, resulting both in intense droughts and in strong flood events. As a result, water is sometimes a scarce resource in this region. The strong population growth and the temperature increase predicted as a result of global climate change will put further pressure on available water resources. However, as this region is also subject to volatile rainfall dynamics, in addition to droughts, the Iishana system also experiences repeated, severe flood events. Most recently, flood events occurred in 2008 to 2011, 2013, and 2017, resulting in the loss of life, the loss of crop yields and consequent loss of livelihood for many people, and the destruction of key infrastructure elements. To date, there has been no complex 2D-hydrodynamic model for the Iishana system and no transferable modeling approach to identify potential locations for water storage and facilitate the planning and development of flood retention measures. In this study, various methods have been developed and applied to address these issues. This has allowed for the validation of existing findings as well as the discovery of new insights, which are briefly summarized below. First, an investigation was performed to test the influence of topography on hydrology, with a special emphasis on infrastructure elements. The focus here was on improving the raw DEM for subsequent calculations. For this purpose, filter corrections were performed on the TanDEM X raw data, and road dams, culverts, and bridges were recorded by means of kinematic surveys. As a result, the definition of the flow paths was improved. It became clear that northern roads, especially those running from east to west, have a strong influence on the runoff behavior in the study area due to their height and their orientation orthogonal to the water flow of the Iishana. Based on the corrected DEM and the application of a modified Blue Spot Analysis, further new findings emerged. Approximately 190,000 pans with a total storage volume of about 1.9 km³ and a total area of 4,021 km² were identified. The part of the study area located in Angola accounts for two thirds of the potential storage volume while only one third of the storage volume is in Namibia. Furthermore, about one third of all pans are located in the episodically water-bearing channels. Based on previous results in other regions, a calculation of the surface-volume relationship (SA/V rate) was performed for the first time for the Iishana system. This enabled the identification of about 2,000 pans that are primarily suitable for an expansion of storage volume. Using continuous and spatio-temporally varying TRMM precipitation data, a 2D-hydrodynamic modeling and reconstruction of the 2008/2009 flood event was performed using the FloodArea model. Although the results represent a snapshot, they nevertheless contribute to an improved understanding of the interconnected runoff system and highlight potential flood hazards. Depending on the weighting of evapotranspiration in the calculation of the model, the potential storage volume can be quantified between 0.116 km³ and 0.547 km³. The total inundation area was calculated at 1.860 km². In addition, three main runoff paths were identified, of which the central and the eastern runoff paths pose a particular threat to the regional capital of Oshakati. Furthermore, with the help of the model, for the first time it was possible to identify areas where, after the end of the rainy season, water availability is naturally shortest (Namibia) or longest (Angola). Based on these numerous, new results, scenario calculations for neighboring catchments as well as calculations for other precipitation periods can be performed in the future. Thus, the duration of water availability after the end of a rainy season can be determined and possible locations for retention measures can be identified for various locations

Array signal processing robust to pointing errors

The objective of this thesis is to design computationally efficient DOA (direction-of- arrival) estimation algorithms and beamformers robust to pointing errors, by harnessing the antenna geometrical information and received signals. Initially, two fast root-MUSIC-type DOA estimation algorithms are developed, which can be applied in arbitrary arrays. Instead of computing all roots, the first proposed iterative algorithm calculates the wanted roots only. The second IDFT-based method obtains the DOAs by scanning a few circles in parallel and thus the rooting is avoided. Both proposed algorithms, with less computational burden, have the asymptotically similar performance to the extended root-MUSIC. The second main contribution in this thesis is concerned with the matched direction beamformer (MDB), without using the interference subspace. The manifold vector of the desired signal is modeled as a vector lying in a known linear subspace, but the associated linear combination vector is otherwise unknown due to pointing errors. This vector can be found by computing the principal eigen-vector of a certain rank-one matrix. Then a MDB is constructed which is robust to both pointing errors and overestimation of the signal subspace dimension. Finally, an interference cancellation beamformer robust to pointing errors is considered. By means of vector space projections, much of the pointing error can be eliminated. A one-step power estimation is derived by using the theory of covariance fitting. Then an estimate-and-subtract interference canceller beamformer is proposed, in which the power inversion problem is avoided and the interferences can be cancelled completely

Development of microwave NDT inspection techniques for large solid propellant rocket motors Final report

Microwave nondestructive testing techniques for large solid propellant rocket engine

Proceedings of International Workshop "Global Computing: Programming Environments, Languages, Security and Analysis of Systems"

According to the IST/ FET proactive initiative on GLOBAL COMPUTING, the goal is to obtain techniques (models, frameworks, methods, algorithms) for constructing systems that are flexible, dependable, secure, robust and efficient. The dominant concerns are not those of representing and manipulating data efficiently but rather those of handling the co-ordination and interaction, security, reliability, robustness, failure modes, and control of risk of the entities in the system and the overall design, description and performance of the system itself. Completely different paradigms of computer science may have to be developed to tackle these issues effectively. The research should concentrate on systems having the following characteristics: • The systems are composed of autonomous computational entities where activity is not centrally controlled, either because global control is impossible or impractical, or because the entities are created or controlled by different owners. • The computational entities are mobile, due to the movement of the physical platforms or by movement of the entity from one platform to another. • The configuration varies over time. For instance, the system is open to the introduction of new computational entities and likewise their deletion. The behaviour of the entities may vary over time. • The systems operate with incomplete information about the environment. For instance, information becomes rapidly out of date and mobility requires information about the environment to be discovered. The ultimate goal of the research action is to provide a solid scientific foundation for the design of such systems, and to lay the groundwork for achieving effective principles for building and analysing such systems. This workshop covers the aspects related to languages and programming environments as well as analysis of systems and resources involving 9 projects (AGILE , DART, DEGAS , MIKADO, MRG, MYTHS, PEPITO, PROFUNDIS, SECURE) out of the 13 founded under the initiative. After an year from the start of the projects, the goal of the workshop is to fix the state of the art on the topics covered by the two clusters related to programming environments and analysis of systems as well as to devise strategies and new ideas to profitably continue the research effort towards the overall objective of the initiative. We acknowledge the Dipartimento di Informatica and Tlc of the University of Trento, the Comune di Rovereto, the project DEGAS for partially funding the event and the Events and Meetings Office of the University of Trento for the valuable collaboration

Multimission Aircraft Design Study, Payload

It is proposed that a Multi-Mission Aircraft (MMA) be prepared to combine some or all the functions of the aging AWACS, JSTARS, RIVET JOINT, COMPASS CALL, and AECCC fleet. Three different thesis studies have been developed by three Air Force Institute of Technology GSE students to show the feasibility of replacing the current aging fleet with one or more MMA platforms. This is the thesis in which the payload issuer have been examined. Within this thesis, two different alternative architectures, which are One Tail Number and Different Tail Numbers including nine different configurations, have been considered. Estimated payload characteristics of these alternatives have been compared to those of Boeing 767-400ER, which is the aircraft selected as the baseline for MMA platform. Reduced life cycle cost, increased measure of aircraft specifications, and minimum risk are the main objectives pursued by means of several systems engineering and aircraft design methodologies

Cyber vulnerabilities in the aviation ecosystem: reducing the attack surface through an international aviation trust framework

Now, at the beginning of the 21st century, the aviation system is well developed, however, the community is at similar juncture as the beginning of the 2oth century, only this time the civil aviation system itself is being rapidly transformed by a wave of digital technologies that hold great promise but could also expose the aviation system to new threats. Certain aspects of the digital transformation of the aviation system, based on network connectivity, must be guided to ensure that it generates ever higher-levels of global interoperability and safety. To address this challenge, it is necessary to go back to fundamental principles. It is necessary to establish a system of identity and trust that integrates the wisdom of the Chicago Convention into the digital world that is already overtaking the aviation industry. Service providers, aircraft manufactures, and avionic producers, are all putting in place their own systems of identity and trust as a matter of necessity. That means, in the near future, an aircraft may need different digital certificates to connect with its satellite communications service provider, retrieve data from the airline operations centre, update its avionics software, download engines monitoring data and other functions. The potential number of proprietary secure links is nearly endless. This patchwork of disparate efforts to reduce the attack surface to air and ground operations will add complexity to the system that will be costly to maintain and will offer a myriad of gaps for adversaries to exploit. In the absence of global direction, different manufactures and different States will take different approaches. However, if a globally acceptable system for identity and trust that can be used by manned and unmanned aircraft indistinctively as well as by different service providers and users is available it would likely be embraced by many or all. As such, based on the new vulnerabilities brought by the evolution of the air navigation system through the intense use of digital and connected technologies, the object of this research relates to the vulnerabilities of the aviation system to a cyber-attack and the objective of this thesis is to propose a concept of operations that allows the implementation of a framework able to provide positive digital identification of all members of the aviation community through specific processes and procedures and a virtual network able to preserve the confidentiality, integrity and availability of the data and information being exchanged at the same time it increases the resilience of operations.Atualmente, no início do século vinte e um, a aviação está em uma situação similar ao início do século vinte, entretanto, desta vez, o sistema de aviação civil está bem consolidado, mas se transformando rapidamente motivado por uma onda de novas tecnologias que apresentam grandes promessas, mas que ao mesmo tempo podem expor a aviação a novas ameaças. Certos aspectos da transformação digital do sistema de aviação civil, baseado em redes que permitem ampla conectividade, devem ser corretamente orientados para garantir níveis globais de segurança e interoperabilidade ainda mais elevados. Para enfrentar esse desafio, necessário se faz o estabelecimento de um sistema de identidades digitais e confiança que integre a sabedoria da Convenção de Chicago ao mundo digital que está invadindo a indústria da aviação. Provedores de serviços, fabricantes de aeronaves e aviônicos estão todos colocando em prática seus próprios sistemas de identificação e confiança por necessidade. Isso significa que em um futuro próximo, uma aeronave poderá precisar de diferentes certificados para conectar-se com seus provedores de comunicações por satélite, receber dados de um centro de coordenação de uma compania aérea, atualizar programas em seus aviônicos, baixar dados para monitoramento do funcionamento de seus motores e outras funções. Esse conjunto de iniciativas isoladas para se reduzir a superfície de ataque cibernético para operações no solo e no ar adicionam complexidade ao sistema considerando que essas iniciativas isoladas tornam o sistema como um todo custoso para se manter e também oferecem uma série de vulnerabilidades a serem exploradas por atores mal intencionados. Na ausência de uma direção global, diferentes fabricantes, provedores de serviços e Estados tomarão direções distintas. Entretanto, se um sistema global de identificação digital e confiança que possa ser usado indistintamente pela aviação tripulada e não tripulada, por provedores de serviços, fabricantes e usuários for posto em prática, é muito provável que o mesmo seja adotado por todos dentro do sistema de aviação civil. Portanto, baseado nas novas vulnerabilidades que a evolução dos sistemas de navegação aérea estão trazendo com o uso intenso de tecnologias digitais e conectadas, o objeto desta tese está relacionado às vulnerabilidades do sistema de aviação civil a um ataque cibernético e o objetivo foi o de propor um conceito operacional que permitisse a implementação de uma estrutura capaz de identificar todos os atores da comunidade de aviação civil através de procedimentos e processos específicos e uma rede virtual para preservar a confidencialidade, a integridade e a disponibilidade das informações e dados sendo intercambiados ao mesmo tempo em que a resiliência do sistema é melhorada através de uma arquitetura específica

Precise positioning of autonomous vehicles combining UWB ranging estimations with on-board sensors

In this paper, we analyze the performance of a positioning system based on the fusion of Ultra-Wideband (UWB) ranging estimates together with odometry and inertial data from the vehicle. For carrying out this data fusion, an Extended Kalman Filter (EKF) has been used. Furthermore, a post-processing algorithm has been designed to remove the Non Line-Of-Sight (NLOS) UWB ranging estimates to further improve the accuracy of the proposed solution. This solution has been tested using both a simulated environment and a real environment. This research work is in the scope of the PRoPART European Project. The different real tests have been performed on the AstaZero proving ground using a Radio Control car (RC car) developed by RISE (Research Institutes of Sweden) as testing platform. Thus, a real time positioning solution has been achieved complying with the accuracy requirements for the PRoPART use case

Signals and Images in Sea Technologies

Life below water is the 14th Sustainable Development Goal (SDG) envisaged by the United Nations and is aimed at conserving and sustainably using the oceans, seas, and marine resources for sustainable development. It is not difficult to argue that signals and image technologies may play an essential role in achieving the foreseen targets linked to SDG 14. Besides increasing the general knowledge of ocean health by means of data analysis, methodologies based on signal and image processing can be helpful in environmental monitoring, in protecting and restoring ecosystems, in finding new sensor technologies for green routing and eco-friendly ships, in providing tools for implementing best practices for sustainable fishing, as well as in defining frameworks and intelligent systems for enforcing sea law and making the sea a safer and more secure place. Imaging is also a key element for the exploration of the underwater world for various scopes, ranging from the predictive maintenance of sub-sea pipelines and other infrastructure projects, to the discovery, documentation, and protection of sunken cultural heritage. The scope of this Special Issue encompasses investigations into techniques and ICT approaches and, in particular, the study and application of signal- and image-based methods and, in turn, exploration of the advantages of their application in the previously mentioned areas