Interference analysis of and dynamic channel assignment algorithms in TD–CDMA/TDD systems

The radio frequency spectrum for commercial wireless communications has become an expensive commodity. Consequently, radio access techniques are required which enable the efficient exploitation of these resources. This, however, is a difficult task due to an increasing diversity of wireless services. Hence, in order to achieve acceptable spectrum efficiency a flexible air– interface is required. It has been demonstrated that code division multiple access (CDMA) provides flexibility by enabling efficient multi user access in a cellular environment. In addition, time division duplex (TDD) as compared to frequency division duplex (FDD) represents an appropriate method to cater for the asymmetric use of a duplex channel. However, the TDD technique is subject to additional interference mechanisms in particular if neighbouring cells require different rates of asymmetry. If TDD is combined with an interference limited multiple access technique such as CDMA, the additional interference mechanism represents an important issue. This issue poses the question of whether a CDMA/TDD air–interface can be used in a cellular environment. The problems are eased if a hybrid TDMA (time division multiple access) / CDMA interface (TD–CDMA) is used. The reason for this is that the TDMA component adds another degree of freedom which can be utilised to avoid interference. This, however, requires special channel assignment techniques. This thesis analyses cellular CDMA/TDD systems used in indoor environments. A key parameter investigated is the interference in such systems. In the interference analysis a special focus is placed on adjacent channel interference since the jamming entity and victim entity can be in close proximity. The interference analysis shows that co–location of BS’s using adjacent channels is not feasible for an adjacent channel protection factor that is less than 40 dB and frame synchronisation errors of more than 10%. Furthermore, it is demonstrated that ideal frame synchronisation does not necessarily yield the highest capacity. As a consequence, a new technique termed ’TS–opposing’ is introduced. This method is intended to enable a cellular TD–CDMA/TDD system to apply cell independent channel asymmetry. For this purpose, a centralised DCA is developed. It is found that this algorithm indeed enables neighbouring cells to adopt different rates of asymmetry without a significant capacity loss. Moreover, a decentralised DCA algorithm based on the TS–opposing principle is developed. In this context, a novel TS assignment concept is proposed which reduces the complexity associated with the TS–opposing technique. In addition, the TS assignment plan allows for full spatial coverage. It is shown that the capacity of a TD–CDMA/TDD interface can be greater than the capacity of an equivalent FDD interface. The performance of the decentralised DCA algorithm is limited by the interference in the uplink. Therefore, additional methods which assist in reducing the interference in the uplink are envisaged to further improve the performance of the decentralised DCA algorithm. The exploitation of the TS–opposing technique in two different ways demonstrates that this method can be used to improve the performance of a TD–CDMA/TDD system significantly

Interference Mitigation in Frequency Hopping Ad Hoc Networks

Radio systems today exhibit a degree of flexibility that was unheard of only a few years ago. Software-defined radio architectures have emerged that are able to service large swathes of spectrum, covering up to several GHz in the UHF bands. This dissertation investigates interference mitigation techniques in frequency hopping ad hoc networks that are capable of exploiting the frequency agility of software-defined radio platforms

Detection performance and mitigation techniques in CR networks

Pervasive wireless communications rely enormously on spectrum utilization; the increase in demand for new wireless services and their application has led to spectrum scarcity. Spectrum limitations can be resolved by cognitive radio (CR) which is a technology that allows secondary users (SUs) to use the spectrum when it is not occupied by primary users (PUs). In this thesis, the security issues that decrease CR performance are discussed; there are two major threats i.e. primary user emulation attack (PUEA) and spectrum sensing data falsification attack (SSDF). Firstly, the CR network (CRN) is simulated whereby PUs and SUs are presented in the system with the presence of multiple malicious users that are randomly located within a circle of radius (R). The simulation results, based on an analytical model, show that the false alarm probability is significantly affected by the network radius Rand malicious users' number, and it is proved that there is a range of R over which the PUEAs are most successful. Secondly, a transmitter verification scheme (direct scheme) and indirect trust scheme that considers the users' history are presented; the results proved that if the signal to noise ratio (SNR) is raised, correspondingly the t:rnstworthiness of the PU is considerably increased. Based on these two schemes, the trnstworthiness of the PU is much higher than that of the malicious user and because the indirect scheme considers the historical behaviour of the user, it improves the user's trustworthiness.Finally, cooperative spectrum sensing (CSS) approaches are proposed, namely, a trust based approach, a punishment based approach and a dedicated punishment based approach. It is proved that these proposed CSS approaches outperform the traditional majority scheme despite a high number of malicious users. In addition, the dedicated punishment approaches which punish only the malicious users outperform the other approaches

Cooperative Radio Communications for Green Smart Environments

The demand for mobile connectivity is continuously increasing, and by 2020 Mobile and Wireless Communications will serve not only very dense populations of mobile phones and nomadic computers, but also the expected multiplicity of devices and sensors located in machines, vehicles, health systems and city infrastructures. Future Mobile Networks are then faced with many new scenarios and use cases, which will load the networks with different data traffic patterns, in new or shared spectrum bands, creating new specific requirements. This book addresses both the techniques to model, analyse and optimise the radio links and transmission systems in such scenarios, together with the most advanced radio access, resource management and mobile networking technologies. This text summarises the work performed by more than 500 researchers from more than 120 institutions in Europe, America and Asia, from both academia and industries, within the framework of the COST IC1004 Action on "Cooperative Radio Communications for Green and Smart Environments". The book will have appeal to graduates and researchers in the Radio Communications area, and also to engineers working in the Wireless industry. Topics discussed in this book include: • Radio waves propagation phenomena in diverse urban, indoor, vehicular and body environments• Measurements, characterization, and modelling of radio channels beyond 4G networks• Key issues in Vehicle (V2X) communication• Wireless Body Area Networks, including specific Radio Channel Models for WBANs• Energy efficiency and resource management enhancements in Radio Access Networks• Definitions and models for the virtualised and cloud RAN architectures• Advances on feasible indoor localization and tracking techniques• Recent findings and innovations in antenna systems for communications• Physical Layer Network Coding for next generation wireless systems• Methods and techniques for MIMO Over the Air (OTA) testin

Cooperative Radio Communications for Green Smart Environments

The demand for mobile connectivity is continuously increasing, and by 2020 Mobile and Wireless Communications will serve not only very dense populations of mobile phones and nomadic computers, but also the expected multiplicity of devices and sensors located in machines, vehicles, health systems and city infrastructures. Future Mobile Networks are then faced with many new scenarios and use cases, which will load the networks with different data traffic patterns, in new or shared spectrum bands, creating new specific requirements. This book addresses both the techniques to model, analyse and optimise the radio links and transmission systems in such scenarios, together with the most advanced radio access, resource management and mobile networking technologies. This text summarises the work performed by more than 500 researchers from more than 120 institutions in Europe, America and Asia, from both academia and industries, within the framework of the COST IC1004 Action on "Cooperative Radio Communications for Green and Smart Environments". The book will have appeal to graduates and researchers in the Radio Communications area, and also to engineers working in the Wireless industry. Topics discussed in this book include: • Radio waves propagation phenomena in diverse urban, indoor, vehicular and body environments• Measurements, characterization, and modelling of radio channels beyond 4G networks• Key issues in Vehicle (V2X) communication• Wireless Body Area Networks, including specific Radio Channel Models for WBANs• Energy efficiency and resource management enhancements in Radio Access Networks• Definitions and models for the virtualised and cloud RAN architectures• Advances on feasible indoor localization and tracking techniques• Recent findings and innovations in antenna systems for communications• Physical Layer Network Coding for next generation wireless systems• Methods and techniques for MIMO Over the Air (OTA) testin

Avaliações hidrológicas, hidráulicas e multicriteriais de susceptibilidade às inundações em áreas urbanas costeiras : estudo de caso da bacia do Rio Juqueriquerê no Brasil

Orientadores: Antonio Carlos Zuffo, Monzur Alam ImteazTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo e Swinburne University of Technology (Australia)Resumo: O desenvolvimento significativo de Caraguatatuba é traduzido pela sua potencialidade ao turismo, exploração de gás, proximidade do Porto de São Sebastião e ampliação do complexo viário da Tamoios, particularmente na Bacia do Rio Juqueriquerê, que é a maior planície não urbanizada do litoral norte de São Paulo, Brasil. A área é constituída por baixas declividades e lençóis freáticos rasos, cercada pelas altas escarpas da Serra do Mar. Além disso, é afetada por chuvas orográficas e variação de marés, contribuindo para a ocorrência natural de inundações. Apesar da área à jusante ser densamente urbanizada, a bacia não é propriamente monitorada, tornando a previsão de futuros cenários com a tradicional modelagem hidrológica muito desafiadora, devido à falta de dados representativos. No presente estudo, a análise multicriterial para tomada de decisão (MCDA) foi utilizada para determinar os critérios mais impactantes na susceptibilidade às inundações do local. O cenário futuro foi baseado no uso e cobertura da terra proposto pelo Plano Diretor de Caraguatatuba. A pesquisa com especialistas usando o método Delphi e o Processo de Análise Hierárquica (AHP) foram associados para a atribuição e comparação por pares dos seguintes critérios: elevação, densidade de drenagem, chuva, declividade e Curva Número (CN), do Serviço de Conservação do Solo (SCS) dos Estados Unidos. A bacia foi discretizada em 11 sub-bacias, e vários métodos estatísticos e empíricos foram empregados para a parametrização do modelo multicriterial. Após a definição dos critérios e tratamento estatístico dos julgamentos de todos os especialistas, uma faixa limitada de pesos foi gerada, variando de 8,36 a 8,88, a qual foi efetivamente convertida para uma ampla faixa de valores de prioridade pelo uso de uma abordagem extendida do método AHP. A escala de julgamento da raiz quadrada aplicada no estudo gerou resultados de boa qualidade, onde a taxa de consistência foi de 0,0218 e o índice de consistência foi de 0,0244. Além disso, a análise de sensibilidade revelou a coerência do vetor peso, por meio da variação do critério de elevação (+10 % e -5%), afetando os pesos mas não a hierarquia. Posteriormente, todos os critérios foram implementados no sistema de informações geográficas (SIG). Foi realizada uma discussão minuciosa sobre a aquisição da variável CN, levando em consideração os tipos de solo brasileiros e as condições de saturação locais. As limitações do método SCS-CN foram destacadas, especialmente no que se refere à sua aplicação em bacias não monitoradas, quando não é possível calibrar ou validar o modelo. A estimativa e a calibração dos coeficientes de rugosidade de Manning nos principais cursos d'água também foram desenvolvidas no estudo, com base nos dados observados e medidos em trabalhos de campo. Os desvios médios absolutos entre os valores de Manning variaram de 0,004 a 0,008, mostrando que a metodologia proposta pode ser aplicada em quaisquer áreas de estudo, tanto para calibrar quanto para atualizar os coeficientes de rugosidade de Manning em diferentes períodos. A distribuição da função gamma foi utilizada para o cálculo das chuvas de projeto, que posteriormente foram utilizadas para a análise de correlação entre chuvas anuais e diárias. O Sistema de Análise Fluvial do Centro de Engenharia Hidrológica em 2 dimensões (HEC-RAS 2D) e o Sistema de Modelagem Hidrológica (HEC-HMS) foram utilizados para a calibração do parâmetro CN e para a validação do modelo. Os limites de inundação gerados no processo de vadidação (pelo modelo HEC-RAS 2D) foram muito similares aos gerados pela abordagem MCDA, correspondendo a 93,92 % e 96,31 %, respectivamente. Os métodos de interpolação foram essenciais para a distribuição temporal e espacial dos dados meteorológicos no modelo de precipitação-vazão usados para validação, e também no modelo MCDA implementado no SIG. A determinação final da probabilidade de susceptibilidade às inundações nas planícies estudadas foi baseada na soma ponderada espacial dos critérios atribuídos previamente. Por fim, os mapas de susceptibilidade às inundações foram gerados para os diferentes cenários. As simulações de diferentes padrões de chuva mostraram que este critério influenciou fortemente na probabilidade de suscetibilidade às inundações. Para a simulação de maiores elevações e chuvas máximas, o índice de susceptibilidade às inundações foi 4 (do total de 5). A maior contribuição do estudo foi na aquisição de parâmetros confiáveis por meio das técnicas propostas, que também podem ser utilizadas em outras áreas, principalmente onde os dados são escassos e há complexas limitações físicas envolvidas, visando o desenvolvimento urbano sustentável da regiãoAbstract: The significant development of Caraguatatuba Municipality is translated by its tourism potentiality, gas exploration, proximity to the Port of Sao Sebastiao and extension of the Tamoios Highway complex, particularly in the Juqueriquere River Basin, which is the major non-urbanised plains of the northern coastline of Sao Paulo, Brazil. The area is comprised of low slopes and shallow water tables, surrounded by the high elevations of the Serra do Mar mountains. Additionally, It is affected by orographic rainfalls and tide variation, contributing to the natural occurrence of floods. Even though the downstream area is densely urbanised, the watershed is not properly gauged, making it a challenging task for the prediction of future scenarios with the traditional hydrological modelling approach, due to the lack of representative data. In the current study, multicriteria decision analysis (MCDA) were used to determine the mostly impacting criteria to the local flood susceptibility. The future scenario was based on the land use and land cover proposed by the City Master Plan of Caraguatatuba. The expert-based survey using the Delphi method and the analytical hierarchical process (AHP) were associated with the attribution and pairwise comparison of the following criteria: elevation, density drainage, rainfall, slope and curve number (CN), from the US Soil Conservation Service (SCS). The watershed was discretised in 11 sub-basins, and several statistical and empirical methods were employed for the parameterisation of the multicriteria model. After the definition of the criteria and the statistical treatment of the judgements of all experts, a limited range of weights was derived, varying from 8.36 to 8.88, which was effectively converted to a larger ratio of priority values by the use of an extended approach of the AHP methodology. The root square judgement scale applied in the study generated good-quality results, where the consistency ratio was 0.0218 and the consistency index was 0.0244. Besides, the sensitivity analysis revealed the coherence of the weight vector, by the variation of the elevation criterion (+10 % and -5%), affecting the weights but not the hierarchy. Further, all the criteria were implemented in the geographical information system (GIS). There was a thorough discussion regarding the acquisition of the CN variable, taking into consideration the Brazilian soil types and the local saturated conditions. The constraints of the SCS-CN method were highlighted, especially regarding its application in ungauged basins, where it is not possible to calibrate or validate the model. The estimation and calibration of the Manning's roughness coefficients of the main watercourses were also developed in the study, based on the observed and measured data in field campaigns. The mean absolute deviations between the estimated and the calibrated Manning's values varied from 0.004 and 0.008, showing that the proposed methodology might be applied in any study areas, both to calibrate and to update the Manning's roughness coefficients in different periods. The gamma-function distribution was carried out to calculate the design rainfalls, which were later used for the correlation analysis of the annual and the daily rainfalls. The Hydrologic Engineering Center's River Analysis System 2D (HEC-RAS 2D) and the Hydrologic Modelling System (HEC-HMS) were used for the calibration of the CN variable and for the model validation. The inundation boundaries derived in the validation process (by the HEC-RAS 2D model) were very similar to the ones achieved by the MCDA approach, corresponding to 93.92 % and 96.31 %, respectively. The interpolation methods were essential for the spatial and temporal distribution of the meteorological data in the rainfall-runoff model used for validation, and also in the GIS-based MCDA model. The final determination of the likelihood of flood susceptibility in the studied plains was based on the spatially weighted summation of the previously attributed criteria. Finally, flood susceptibility maps were generated for the different scenarios. The simulations of different rainfall patterns showed that this criterion profoundly influenced the likelihood to flood susceptibility. For the simulation of higher elevations and maximum rainfalls, the achieved index of flood susceptibility was 4 (out of 5). The main contribution of the study was the achievement of reliable parameters by the proposed techniques, that may also be used in other areas, mainly where data is scarce and complex physical constraints are involved, targeting the sustainable urban development of the regionDoutoradoRecursos Hidricos, Energeticos e AmbientaisDoutora em Engenharia Civi

Satellite formation flying for an interferometry mission

The autonomous formation flying of multiple spacecraft to replace a single large satellite will be an enabling technology for many future missions. In this research, the current status of formation flying missions and technologies is determined, and the Darwin nulling interferometry mission, which aims to detect and characterise extrasolar planets, is selected as the research focus. Darwin requires high precision formation flying of multiple telescopes near the Sun-Earth L2 point. A comprehensive account of current research in astrobiology is presented which provides the motivation for a Darwin-type mission. Astrobiology is integral to the definition of formation manoeuvres and target identification. The system design issues associated with developing a higher resolution, Planet Imager mission are also explored through a preliminary mission design. Relative dynamics models for satellite formation flying control in Low Earth Orbit (LEO) and L2 are developed and methods of incorporating the Earth oblateness perturbation (J2) into the equations of relative motion to improve model fidelity are investigated. The linearised J2 effect is included in the Hill equations in time averaged and time varying form. The models are verified against the Satellite Tool Kit (STK) numerical orbit propagator, and applied to optimal control system design and evaluation for formation keeping tasks. The ‘reference orbit’ modelling approach applied in LEO is applied to the development of a new formation flying model at L2. In this case, linearised equations of motion of the mirror satellites relative to the hub are derived and performance evaluated for different initial conditions. These and other higher order models are compared to STK. The linearised model is applied to controller design for station keeping and formation manoeuvring tasks suitable for a Darwin-type mission, and the role of the model in developing controllers for a load levelling guidance system is explored.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Ecosystemic Evolution Feeded by Smart Systems

Information Society is advancing along a route of ecosystemic evolution. ICT and Internet advancements, together with the progression of the systemic approach for enhancement and application of Smart Systems, are grounding such an evolution. The needed approach is therefore expected to evolve by increasingly fitting into the basic requirements of a significant general enhancement of human and social well-being, within all spheres of life (public, private, professional). This implies enhancing and exploiting the net-living virtual space, to make it a virtuous beneficial integration of the real-life space. Meanwhile, contextual evolution of smart cities is aiming at strongly empowering that ecosystemic approach by enhancing and diffusing net-living benefits over our own lived territory, while also incisively targeting a new stable socio-economic local development, according to social, ecological, and economic sustainability requirements. This territorial focus matches with a new glocal vision, which enables a more effective diffusion of benefits in terms of well-being, thus moderating the current global vision primarily fed by a global-scale market development view. Basic technological advancements have thus to be pursued at the system-level. They include system architecting for virtualization of functions, data integration and sharing, flexible basic service composition, and end-service personalization viability, for the operation and interoperation of smart systems, supporting effective net-living advancements in all application fields. Increasing and basically mandatory importance must also be increasingly reserved for human–technical and social–technical factors, as well as to the associated need of empowering the cross-disciplinary approach for related research and innovation. The prospected eco-systemic impact also implies a social pro-active participation, as well as coping with possible negative effects of net-living in terms of social exclusion and isolation, which require incisive actions for a conformal socio-cultural development. In this concern, speed, continuity, and expected long-term duration of innovation processes, pushed by basic technological advancements, make ecosystemic requirements stricter. This evolution requires also a new approach, targeting development of the needed basic and vocational education for net-living, which is to be considered as an engine for the development of the related ‘new living know-how’, as well as of the conformal ‘new making know-how’