The study of large-scale decentralised systems composed of numerous interacting agents that self-organise to perform a common task is receiving growing attention in several application domains. However, real world implementations are limited by a lack of well-established design methodologies that provide performance guarantees. Engineering such systems is a challenging task because of the difficulties to obtain the micro-macro link: a correspondence between the microscopic description of the individual agent behaviour and the macroscopic models that describe the system's dynamics at the global level. In this thesis, we propose an engineering methodology for designing decentralised systems, based on the concept of design patterns. A design pattern provides a general solution to a specific class of problems which are relevant in several application domains. The main component of the solution consists of a multi-level description of the collective process, from macro to micro models, accompanied by rules for converting the model parameters between description levels. In other words, the design pattern provides a formal description of the micro-macro link for a process that tackles a specific class of problems. Additionally, a design pattern provides a set of case studies to illustrate possible implementation alternatives both for simple or particularly challenging scenarios. We present a design pattern for the best-of-n, decentralised decision problem that is derived from a model of nest-site selection in honeybees. We present two case studies to showcase the design pattern usage in (i) a multiagent system interacting through a fully-connected network, and (ii) a swarm of particles moving on a bidimensional plane. / Doctorat en Sciences de l'ingénieur et technologie / info:eu-repo/semantics/nonPublished

As the communication deficit in the Arctic region is enormous especially above 75 [Deg] N latitude, the concern and opportunity of providing reliable & efficient connectivity in the Arctic region has beenduly noted & understood by N66 Connect AB (N66). This case study documents a comprehensive research which implements system engineering approach for establishment of a Ground Station (GS) at Svalbard, Norway with sole focus of connecting the inaccessible geographical region lying in the Arctic with rest of the world. Several GS system & subsystem are studied and comparative analysis is made on how the communication can be established with the N66 Connect AB (N66)’s potential clients and its satellites that are to be deployed in September, 2018.The case study resulted in analysis of several risks involved during development & operation of the GS,the hardware, software & operational architecture, the features of GS’s system capable of meeting N66’s objectives and the market potential of the service after GS operations.

Abstract Advanced multiple-input multiple-output (MIMO) transceiver structures which utilize the knowledge of channel state information (CSI) at the transmitter side to optimize certain link parameters (e.g., throughput, fairness, spectral efficiency, etc.) under different constraints (e.g., maximum transmitted power, minimum quality of services (QoS), etc.) are considered in this thesis. Adaptive transmission schemes for point-to-point MIMO systems are considered first. A robust link adaptation method for time-division duplex systems employing MIMO-OFDM channel eigenmode based transmission is developed. A low complexity bit and power loading algorithm which requires low signaling overhead is proposed. Two algorithms for computing the sum-capacity of MIMO downlink channels with full CSI knowledge are derived. The first one is based on the iterative waterfilling method. The convergence of the algorithm is proved analytically and the computer simulations show that the algorithm converges faster than the earlier variants of sum power constrained iterative waterfilling algorithms. The second algorithm is based on the dual decomposition method. By tracking the instantaneous error in the inner loop, a faster version is developed. The problem of linear transceiver design in MIMO downlink channels is considered for a case when the full CSI of scheduled users only is available at the transmitter. General methods for joint power control and linear transmit and receive beamformers design are provided. The proposed algorithms can handle multiple antennas at the base station and at the mobile terminals with an arbitrary number of data streams per scheduled user. The optimization criteria are fairly general and include sum power minimization under the minimum signal-to-interference-plus-noise ratio (SINR) constraint per data stream, the balancing of SINR values among data streams, minimum SINR maximization, weighted sum-rate maximization, and weighted sum mean square error minimization. Besides the traditional sum power constraint on the transmit beamformers, multiple sum power constraints can be imposed on arbitrary subsets of the transmit antennas.This extends the applicability of the results to novel system architectures, such as cooperative base station transmission using distributed MIMO antennas. By imposing per antenna power constraints, issues related to the linearity of the power amplifiers can be handled as well. The original linear transceiver design problems are decomposed as a series of remarkably simpler optimization problems which can be efficiently solved by using standard convex optimization techniques. The advantage of this approach is that it can be easily extended to accommodate various supplementary constraints such as upper and/or lower bounds for the SINR values and guaranteed QoS for different subsets of users. The ability to handle transceiver optimization problems where a network-centric objective (e.g., aggregate throughput or transmitted power) is optimized subject to user-centric constraints (e.g., minimum QoS requirements) is an important feature which must be supported by future broadband communication systems.

Abstract This thesis seeks to develop a robust semi-analytical performance prediction method for an advanced iterative receiver that processes spatially multiplexed signals that have propagated through frequency-selective receive correlated multiple-input multiple-output (MIMO) wireless communication channels. In a change of perspective, the proposed performance prediction methods are applied at the transmitter, which seeks to attain a target frame error rate (FER) either by adaptive power control or by adaptive modulation and coding (AMC). The performance prediction scheme utilises the statistical properties of the channel—namely noise variance, number of separable propagation paths and the eigenvalues of the receive correlation matrix—to predict the signal-to-interference-plus-noise ratio (SINR) at the output of a frequency domain soft interference cancellation minimum mean square error equaliser. The SINR distribution is used to derive the distribution of the variance of the log-likelihood ratios (LLRs) at the output of a soft symbol-to-bit demapper. Mutual information transfer charts establish a bijective relationship between the variance of the LLRs and mutual information. A 3rd Generation Partnership Project compliant turbo code is assumed. Since the decoder operates independently from the channel, its extrinsic information transfer (EXIT) charts can be simulated in advance. By utilising the approximate LLR variance distribution of the demapped equaliser output, it is possible to evaluate the probability of an intersection between an equaliser chart associated with a random channel realisation and a fixed decoder chart. This probability provides the FER. Since the proposed performance prediction method does not require any instantaneous channel state information, it can be applied at the transmitter side as a robust link adaptation scheme. In adaptive transmission power control, the modulation order and code rate are fixed. By iteratively adjusting transmission power, the transmitter attempts to find an equaliser output LLR variance distribution that reaches a specified target FER. In AMC, transmission power is fixed. The equaliser output's LLR variance distribution is determined by the modulation order, while the decoder chart's position is determined by the code rate. The transmitter iteratively adjusts the code rate and attempts to find a modulation order and code rate pairing that reaches the target FER. For vertically encoded spatially multiplexed systems, the adaptive transmission power control and AMC schemes are complemented by adaptive repeat redundancy and incremental redundancy hybrid automatic repeat request (HARQ) techniques, respectively. / Tiivistelmä Työn tavoitteena on kehittää luotettava semianalyyttinen suorituskyvyn ennustusmenetelmä tehokkaalle iteratiiviselle vastaanottimelle, joka käsittelee taajuusselektiivisen, vastaanotinpäässä tilakorreloituneen moniantennikanavan kautta kulkeneita tilakanavoituja signaaleja. Toisessa vaiheessa esitettyjä ennustusmenetelmiä hyödynnetään mukauttamalla lähetystehoa tai modulaatioastetta ja koodisuhdetta (adaptive modulation and coding [AMC]), samalla säilyttäen tavoitteeksi asetetun kehysvirhesuhteen (frame error rate [FER]). Suorituskyvyn ennustusmenetelmä hyödyntää kanavan tilastollisia ominaisuuksia – kohinan varianssia, eroteltavien etenemispolkujen lukumäärää sekä vastaanottimen korrelaatiomatriisin ominaisarvoja – ennustaakseen signaali–kohina-plus-interferenssisuhteen (signal-to-interference-plus-noise ratio [SINR]) jakauman taajuustasossa toimivan, häiriötä poistavan pienimmän keskineliösumman kanavakorjaimen lähdössä. SINR-jakaumasta johdetaan pehmän symboleista biteiksi -muunnoksen jälkeisten logaritmisten bittitodennäköisyyksien suhdelukujen (log-likelihood ratio [LLR]) jakauma. Keskinäisinformaation siirroskartat perustuvat LLR:ien varianssin sekä keskinäisinformaation väliseen bijektiivisyyteen. Informaatio on kanavakoodattu 3rd Generation Partnership Project -standardin mukaisella turbokoodilla. Turbodekooderin toiminta on kanavasta riippumatonta, joten dekooderin lisäinformaation siirroskartat (extrinsic information transfer [EXIT] charts) voidaan simuloida itsenäisesti. Hyödyntämällä kanavakorjaimen lähdön pehmeiden bittipäätösten LLR:ien varianssin jakaumaa, on mahdollista arvioida millä todennäköisyydellä korjaimen satunnaisen kanavarealisaation siirroskartta leikkaa dekooderin siirroskartan. Tämä todennäköisyys voidaan tulkita kehysvirhesuhteeksi. Koska suorituskyvyn ennustusmenetelmä ei vaadi hetkellistä tietoa kanavan tilasta, sitä voidaan hyödyntää lähetyksen mukautuksessa. Mukautuvassa tehonsäädössä modulaatio ja koodisuhde eivät muutu. Lähetin pyrkii iteratiivisella tehonsäädöllä löytämään korjaimen lähdölle LLR-jakauman, joka tuottaa halutun kehysvirhesuhteen. Mukautuvassa modulaation ja koodisuhteen valinnassa lähetysteho säilyy vakiona. Modulaatioaste vaikuttaa korjaimen lähdön LLR-jakaumaan ja koodisuhde dekooderin siirroskartan muotoon. Iteratiivisesti koodisuhdetta säätämällä lähetin pyrkii löytämään modulaation ja koodisuhteen yhdistelmän, joka saavuttaa tavoitellun kehysvirhesuhteen. Vertikaalisesti tilakanavoiduissa järjestelmissä mukautuvaa tehonsäätöä täydennetään lähetystehoa mukauttavilla uudellenlähetyksillä, kun taas mukautuvaa modulaation ja koodisuhteen valintaa täydennetään puolestaan koodisuhdetta pienentävillä automattisilla uudelleenlähetyspyynnöillä (hybrid automatic repeat request [HARQ]).

L’étude du sujet et du lien social tels que Lacan les a conceptualisés semble d’emblée problématique lorsqu’il s’agit de les soumettre à l’épreuve de l’histoire. Cette problématique relance le débat de la difficile articulation de la structure et de l’histoire. Il apparaît important de réinvestir ce questionnement parce qu’il semble au fondement d’une controverse plus contemporaine émanant de l’étude des rapports qu’entretient le sujet avec le social et ses mutations. En explorant les déplacements se réalisant dans la structure du sujet, nous exploiterons l’histoire, en tant qu’étude du changement, afin d’entrevoir la manière dont elle se réalise au sein du sujet et du lien social. Nous tenterons d’éclairer comment le sujet est réactif à l’événement que nous différencions du fait social et dégagerons une temporalité permettant d’unir l’ordre synchronique et l’ordre diachronique s’incarnant simultanément dans la structure du sujet et du lien social. / The study of the subject and of the social link as conceptualized by Lacan seems problematic as soon as these are exposed to the test of history. This problematic revives the debate about the difficulty of articulating structure and history. It seems important to re-examine this question because it appears to underlie a more contemporary controversy which comes from the study of the relationships the subject maintains with its social context and its variants. By exploring the changes occurring in the subject’s structure, we will use history as a means to study this change. We will try to identify the way it happens both within the subject and within the social link. We will attempt to elucidate how the subject is responsive to the event, which we will distinguish from the social context. We will afterwards identify a temporality enabling us to bring together the synchronic and the diachronic orders at work simultaneously in both the structure of the subject and of the social link.

Approved for public release; distribution is unlimited. / In military operations, covertness of operation is of paramount importance. The transmission power of the data link must be kept to the minimum to maintain a low probability of detection (LPD) from the adversary. However, a reduction in the transmitted power implies a reduction in the operating range, though the detection range by the enemy is also reduced. Therefore, to reduce the enemy’s detection range while maintaining operating distance, this thesis explores strategies to discriminate gain against an adversary’s sensor. The strategies involve using processing gain, directional antennas, polarization and the natural environment as a transmission shield. The processing gain strategy analyzed in this thesis uses a diversity technique called Maximal Ratio Combining (MRC) applied to an IEEE 802.16a link. Sinclair D. Smith carried out a study on the possible processing gain derivable from this technique and this thesis will bring his results to practical applications via link analyses. In the event that the link is detected and the enemy decides to carry out jamming, the thesis explores a possible anti-jamming (AJ) strategy by using MRC and a directional antenna. Daniel P. Zastrow carried out a study on the AJ capability of MRC and this thesis brings his results to practical applications via link analyses. / Major, Republic of Singapore Airforce

The invention of closed circuit television (CCTV) has initiated a new trend in high security by video surveillance. More recently, CCTV cameras have been incorporating wireless LAN technology for data transfer purposes by using on chip memory storage until the time of update. In this thesis, short range communication such as Bluetooth low energy (Bluetooth smart) is used in order to perform simple I/O applications. The two important components of the project are the camera and the Bluetooth module box. An external antenna is designed for the connectivity box and the operating range of the box is deduced by using link budget. The blue cool connectivity box is assessed by defining the capabilities of the box, i.e., simple I/O operations. Field test measurements for the designed antenna provide optimum communication range. The thesis also reviews software simulation tools that are essential for antenna design and path loss modelling. The efficiency of simulated measurements versus real-time measurements are also assessed. The primary target of the thesis is to detail the design of a cost-effective antenna based on link budget calculations and perform basic I/O tasks wirelessly between the blue cool connectivity box and the camera. It is concluded that in future works, advanced operations can be added on to the existing model. It is also suggested that a model for multi floor communication can be designed.

This thesis aim is to study the usage and experience of the sustainability tool SUNRA (Sustainable National Road Agency) as well as the tool's contribution to the Swedish Transport Administration’s sustainability work in the East link project. The usage and the experience with the SUNRA tool is presented partly based on the interviews conducted and by comparing the previous research found in field of sustainability tools. The ambition of ERA-NET Roads was to provide a sustainability tool that is divided into three frameworks and takes a holistic approach to the sustainability issue of traffic authorities in Europe. This study highlights areas that the research emphasizes; Sustainability work and major projects, infrastructure projects and the overall perspective, sustainability tools in projects, and communication of sustainability work. Through a qualitative semi structured interview study, five themes were identified: why SUNRA was chosen, utility usability, structure of sustainability work, organization around SUNRA and how the communication appears in the East link project. The result of the study shows that the usage of the SUNRA tool in many ways correspond with the earlier research, by taking a holistic perspective on the sustainability work and to contribute with a starting point in the sustainability work. The result of the study also shows that the SUNRA-tool doesn’t line with the earlier research when the shaping of and the communication with the tool has not been satisfactory.

Deflation, which has recently represented significant source of concern, is by many economists perceived to be an unfavorable phenomenon in the economy. The aim of this paper is to identify the possible link between deflation and economic downturn based on the comprehensive view. The emphasis is put on the analysis of historical episodes of deflation over the past two centuries in order to shed light on causes and impacts of deflation during the periods. The paper does not neglect the comparison of theoretical approaches. The results of the analysis, supported by empirical studies, imply that the relationship between deflation and recession is complex. Although the paper does not confirm the existence of a general link between deflation and recession, it reveals that recession often leads to deflation (especially in a low inflation environment), but deflation does not usually result in recession. In many cases deflation remains to be a symptom of economic problems, not their cause.

Diferentes sistemas do mundo real podem ser representados por redes. As redes são estruturas nas quais seus vértices (nós) representam entidades e links representam relações entre essas entidades. Além disso, as redes caracterizam-se por ser estruturas dinâmicas, o que implica na rápida aparição e desaparição de entidades e seus relacionamentos. Nesse cenário, um dos problemas importantes a serem enfrentados no contexto das redes, é da predição de links, isto é, prever a ocorrência futura de um link ainda não existente entre dois vértices com base nas informações já existentes. A importância da predição de links deve-se ao fato de ter aplicações na recuperação de informação, identificação de interações espúrias e, ainda, na avaliação de mecanismos de evolução das redes. Para enfrentar o problema da predição de links, a maioria dos métodos utiliza informações da vizinhança topológica das redes para atribuir um valor que represente a probabilidade de conexão futura entre um par de vértices analisados. No entanto, recentemente têm aparecido métodos híbridos, caracterizados por usar outras informações além da vizinhança topológica, sendo as informações das comunidades as normalmente usadas, isso, devido ao fato que, ao serem grupos de vértices densamente ligados entre si e esparsamente ligados com vértices de outros grupos, fornecem informações que podem ser úteis para determinar o comportamento futuro das redes. Assim, neste trabalho são apresentadas duas propostas na linha dos métodos baseados nas informações das comunidades para predição de links. A primeira proposta consiste em um novo índice de similaridade que usa as informações dos vértices pertencentes a mesma comunidade na vizinhança de um par de vértices analisados, bem como as informações dos vértices pertencentes a diferentes comunidades nessa mesma vizinhança. A segunda proposta consiste de um conjunto de índices obtidos a partir da reformulação de algumas propostas já existentes, porém, inserindo neles informações dos vértices pertencentes unicamente à mesma comunidade na vizinhança topológica de um par de vértices analisados. Experimentos realizados em dez redes complexas de diferentes domínios demonstraram que, em geral, os índices propostos obtiveram desempenho superior às abordagens usuais / Different real-world systems can be represented as networks. Networks are structures in which vertices (nodes) represent entities and links represent relationships between these entities. Moreover, networks are dynamic structures, which implies rapid appearance and disappearance of entities and their relationships. In this scenario, the link prediction problem attempts to predict the future existence of a link between a pair of vertices considering existing information. The link prediction importance is due to the fact of having different applications in areas such as information retrieval, identification of spurious interactions, as well as for understanding mechanisms of network evolution. To address the link prediction problem, many proposals use topological information to assign a value that represents the likelihood of a future connection between a pair of vertices. However, hybrid methods have appeared recently. These methods use additional information such as community information. Communities are groups of vertices densely connected among them and sparsely connected to vertices from other groups, providing useful information to determinate the future behavior of networks. So, this research presents two proposals for link prediction based on communities information. The first proposal consists of a new similarity index that uses information about the communities that the vertices in the neighborhood of a analyzed pair of vertices belong. The second proposal is a set of indices obtained from the reformulation of various existing proposals, however, using only the information from vertices belonging to the same community in the neighborhood of a pair of vertices analyzed. Experiments conducted in ten complex networks of different fields show the proposals outperform traditional approaches