Motivated by current applications in multihop transmission and ad hoc networks, the classical three-node relay channel consisting of a source-destination pair and a relay has received significant attention. One of the crucial aspects of the relay channel is the design of proper relaying protocols, i.e., how the relay should take part into transmission. The thesis addresses this problem and provides a partial answer to that. In this thesis, we propose and study two novel relaying protocols. The first one is based on constellation rearrangement (CR) and is suitable for higher-order modulation schemes. With CR, the relay uses a bit-symbol mapping that is different from the one used by the source. We find the optimal bit-symbol mappings for both the source and the relay and the associated optimal detectors, and show that the improvement over conventional relaying with Gray mapping at the source and the relay can amount to a power gain of several dB. This performance improvement comes at no additional power or bandwidth expense, and at virtually no increase in complexity. The second one is a half-duplex decode-and-forward (DF) relaying scheme based on partial repetition (PR) coding at the relay. With PR, if the relay decodes the received message successfully, it re-encodes the message using the same channel code as the one used at the source, but retransmits only a fraction of the codeword. We analyze the proposed scheme and optimize the cooperation level (i.e., the fraction of the message that the relay should transmit). We compare our scheme with conventional repetition in which the relay retransmits the entire decoded message, and with parallel coding, and additionally with dynamic DF. The finite SNR analysis reveals that the proposed partial repetition can provide a gain of several dB over conventional repetition. Surprisingly, the proposed scheme is able to achieve the same performance as that of parallel coding for some relay network configurations, but at a much lower complexity. Additionally, the thesis treats the problem of resource allocation for collaborative transmit diversity using DF protocols with different type of CSI feedback at the source. One interesting observation that emerges is that the joint powerbandwidth allocation only provides marginal gain over the relaying protocols with optimal bandwidth allocation. / QC 20101119

Orbital debris is a current and growing threat to reliable space operations and new space vehicle traffic. As space traffic increases, so does the economic impact of orbital debris on the sustainability of systems that increasingly support national security and international commerce. Much of the debris collision risk is concentrated in specific high-density debris clusters in key regions of Low Earth Orbit (LEO). A potential long-term solution is to employ a constellation of observation satellites within these debris clusters to improve monitoring and characterization efforts, and engage in Laser Debris Removal (LDR) as means of collision mitigation. Here we adapted and improved a previous methodology for evaluating such designs. Further, we performed an analysis on the observer constellations' effectiveness over a range of circular, elliptical, and self-maneuvering designs. Our results show that increasingly complex designs result in improved performance of various criteria and that the proposed method of observation could significantly reduce the threat orbital debris poses to space operations and economic growth. / Master of Science / Orbital debris is defined as all non-operational, man-made objects currently in space. US national space regulations require every new satellite to have a de-orbit plan to prevent the creation of new debris, but fails to address the thousands of derelict objects currently hindering space operations. As space traffic increases, so does the economic impact of orbital debris on the sustainability of systems that increasingly support national security and commercial growth. While orbital debris is usually assessed by looking at the full volume of space, most massive debris objects are concentrated in high-density clusters with a higher than normal probability for collision. A potential solution to the growing orbital debris problem is to place a group of observation satellites within these debris clusters to both improve monitoring capabilities and provide a means for preventing potential collisions by engaging with debris via Laser Debris Removal (LDR). This research presents a methodology for comparing and contrasting different observer satellite constellation designs. Our results show that increasingly complex orbit designs improve various performance criteria, but ultimately orbits that more closely match those of the debris objects provide the best coverage. The proposed method of observation and engagement could significantly reduce the threat orbital debris poses to space operations and economic growth.

La réduction des budgets du domaine spatial et les missions scientifiques traditionnelles ayant des coûts et une complexité croissants a amené la communauté scientifique à se concentrer sur les petits satellites qui fournissent non seulement des résultats scientifiques de valeur, mais permettent aussi de nouvelles applications dans le domaine de la télédétection, de la surveillance environnementale et des télécommunications. De plus, le concept de vol en formation de petits satellites est une technologie-clé pour beaucoup de missions spatiales futures, en améliorant la capacité de survie et réduisant le coût des missions. Ce travail de recherche a un double but : la proposition de modèles innovants de constellations de nano-satellites et de nouvelles approches de routage pour les réseaux de nano-satellites. Cette thèse propose et analyse trois modèles de constellations de nano-satellites dénommés NanoDREAM, NanoiCE et NanoSPHERE, qui fournissent des services de télécommunications aux régions éloignées. Le modèle NanoDREAM est conçu pour le Désert Salar de Uyuni en Bolivie, une région qui détient 70% de la réserve mondiale de lithium. Le modèle NanoiCE est destiné aux Régions Polaires, pour satisfaire les besoins de télécommunications de la communauté scientifique. Le modèle NanoSPHERE est conçu pour fournir une couverture globale de la Terre pour un marché de télécommunications concurrentiel. De plus, nous avons proposé une architecture pour le segment terrestre basée sur la technologie sans fil. Cette architecture a été déployée sur la zone d'exploitation du Désert Salar de Uyuni. Ces modèles ont été développés analytiquement et mis ensuite en œuvre dans le simulateur SaVi afin d'identifier la meilleure constellation satisfaisant les requis de la mission en terme de couverture et en réduisant au minimum le nombre de nano-satellites de la constellation. […] / The growth in cost and complexity of traditional scientific missions along with the reduction in space budgets have determined space community to focus on small satellites that not only provide valuable scientific returns, but also allow completely new applications in remote sensing, environmental monitoring and communications. Furthermore, small satellite flying in formation is a key technology for many future space science missions, by improving mission survivability and reducing mission costs, and offering multi-mission capabilities, achieved through reconfiguration of formations.The main goal of this thesis is two-fold: proposing innovative nanosatellite constellation models andnew routing approaches for nanosatellite network telecommunications. Therefore, this research work proposes and analyzes three models of nanosatellite constellations, named NanoDREAM, NanoiCE, NanoSPHERE, that provide telecommunication services to remote regions of the Earth. NanoDREAM mode! is designed for Bolivia's Salar de Uyuni Desert, a region which detains 70% of the global lithium reserve. NanoiCE model is intended for Polar Regions, in order to meet the voice and data transfer needs of the entire Antarctic and Arctic scientific community. NanoSPHERE is aimed to provide global coverage in the context of a robust telecommunications market. Additionally, a ground segment architecture based on wireless technology and deployed over the exploitation area of Salar de Uyuni Desert was proposed. Moreover, two new methodologies were proposed: the first one is a method for estimating the number of nano-satellites needed to cover a specific region was, and the second one is a Markov modeling­ based method for evaluating the performance of nanosatellite constellations. [...]

Le blanc dans le cinéma de science-fiction vibre et scintille, comme une invitation à l’interpréter. À travers le blanc se tisse un lien entre des images sans rapports apparents, et ce type de connexion hétérogène sollicite notre regard d’une manière qui se rapproche d’un montage. Ce regard facilite de plus le détachement des figures blanches de leurs objets référentiels, du contexte du film, et même du contexte du cinéma. Dans cette vision en forme de constellation, révélant des forces liées à la construction, à la destruction et à l’incertitude, le blanc au sein du cinéma de science-fiction, de par sa nature hybride et changeante, transgresse fréquemment les lois établies de l’espace-temps. Véhiculant des sensations et des pensées variées, le blanc reflète d’une manière indirecte et fragmentaire son époque et révèle avec subtilité son passé virtuel, lequel se caractérise par une grande richesse. À la fois couleur du degré zéro et couleur intégrale, porteur de mémoire tout autant que de nouveauté, le blanc, en raison de son caractère minimal et illimité, démontre une capacité à se déplacer librement dans le monde de la science-fiction, voire d’errer dans l’univers des images... / The colour white in the cinema of science fiction vibrates and sparkles, inviting our interpretations. Unrelated images are linked through whiteness in a form of heterogeneous connection that solicits our gaze as a montage. This look also facilitates the detachment of white figures from their reference objects, the context of the film and even the context of cinema. In this vision of a constellation, which reveals the energies of construction, destruction and uncertainty, whiteness in the cinema of science fiction by its hybrid and changing nature easily transgresses the established laws of space-time. Carrying diverse sensations and thoughts, the colour white reflects its era in a manner at once both indirect and fragmentary, discreetly revealing its virtual but rich past. At once the colour of nothingness and integrating all other colours, saturated with memory but new like a newborn, white with its minimal and unlimited character demonstrates an ability to move freely in the world of science-fiction, and even to wander in the universe of images.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.

Biological and social factors determines human personality. Birth order and its influence rank among strong phenotype forming factors. Practical application of the knowledge is complicated due the lack of evidence in this area in the Czech Republic. In our study, we focused on the role of age-gap between siblings and the role of gender on the birth order in education. Proportion of firstborns in various group of biology students were analysed. We found significantly higher proportions of firstborns than expected. The results were compared to the sample from the years 1990-1995. A small decrease in firstborns representation is observed. We also find big influence of gender and age-gap between siblings on the effects. Decrease in age-gaps increases the proportion of firstborns. Similar effects were found in personality traits data. Our study is unfortunately limited due to small numbers of participants. We suggest replication of our results and further testing of the effects.

Medical imaging technologies such as MRI, CT, PET, etc. enable the use of higher resolution 3D digital image data for research and clinical treatment. The new technologies provide improved spatial resolution at the cost of increased data processing time. Manual identification of anatomical landmarks is still a common practice in many neuroimaging and other medical imaging applications but it is labor-intensive, subjective, and suffers from intra-/inter- rater inconsistency. This work explored one way of estimating a landmark constellation automatically, consistently, and efficiently. The proposed method demonstrated a successful application on how to effectively utilize image processing in tackling clinical challenges. It is shown that the cooperation of spatial localization using linear model prediction with evolutionary principal components and local search estimation using statistical shape models is capable of effectively extracting important landmark detection information from both morphometric relationships of landmarks and consistent intensity distribution of images. It is accurate (compared to 1.6 mm root mean squared errors of manual labeling of brain landmarks), consistent, reliable in predicting many salient midbrain point landmarks such as ac, pc, MPJ, etc. in a longitudinal, multisubject environment, and throughout large datasets with different modalities and image information such as orientation, spacing, and origin. The framework of linear model estimation method using evolutionary principal components and the idea of local search using statistical shape models are generalized to the detection task for arbitrary number of landmarks in other organs, creatures, or even any other physical objects in the world as long as the landmarks present intensity consistency and satisfy regularity in spatial organization.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

This thesis considers the modulation division based on the concept of uniquely factorable constellation pair (UFCP) and uniquely decodable constellation group (UDCG) in multiuser wireless communication networks. We first consider a two-hop relay network consisting of two single-antenna users and a two-antenna relay node, for which a novel distributed concatenated Alamouti code is devised. This new design allows the source and relay nodes to transmit their own information to the destination node concurrently at the symbol level with the aid of the UFCP generated from both PSK and square QAM constellations as well as by jointly processing the noisy signals received at the relay node. Moreover, an asymptotic symbol error probability (SEP) formula is derived for the ML receiver, showing that the maximum diversity gain function is achieved, which is proportional to $\ln \mathtt{SNR}/\mathtt{SNR}^2$. Then, we concentrate on the point-to-point correlated multiple-input and multiple-output (MIMO) communication systems where full knowledge of channel state information (CSI) is available at the receiver and only the first- and second-order statistics of the channels are available at the transmitter. When the number of antenna elements of both ends goes to infinity while keeping their ratio constant, the asymptotic SEP analysis is carried out for either optimally precoded or uniformly precoded correlated large MIMO fading channels using the zero-forcing (ZF) detector with equally likely PAM, PSK or square QAM constellations. For such systems, we reveal some very nice structures which inspire us to explore two very useful mathematical tools (i.e., the Szego's theorem on large Hermitian Toeplitz matrices and the well-known limit: $\lim_{x\to\infty}(1+1/x)^x=e$), for the systematic study of asymptotic behaviors on their error performance. This new approach enables us to attain a very simple expression for the SEP limit as the number of the available antenna elements goes to infinity. In what follows, the problem of precoder design using a zero-forcing decision-feedback (ZF-DF) detector is also addressed. For such a MIMO system, our principal goal is to efficiently design an optimal precoder that minimizes the asymptotic SEP of the ZF-DF detector under a perfect decision feedback. By fully taking advantage of the product majorization relationship among eigenvalues, singular-values and Cholesky values of the precoded channel matrix parameters, a necessary condition for the optimal solution to satisfy is first developed and then the structure of the optimal solution is characterized. With these results, the original non-convex problem is reformulated into a convex one that can be efficiently solved by using an interior-point method. In addition, by scaling up the antenna array size of both terminals without bound for such a network, we propose a novel method as we did for the ZF receiver scenario to analyze the asymptotic SEP performance of an equal-diagonal QRS precoded large MIMO system when employing an abstract Toeplitz correlation model for the transmitter antenna array. This new approach has a simple expression with a fast convergence rate and thus, is efficient and effective for error performance evaluation. For multiuser communication networks, we first consider a discrete-time multiple-input single-output (MISO) Gaussian broadcast channel (BC) where perfect CSI is available at both the transmitter and all the receivers. We propose a flexible and explicit design of a uniquely decomposable constellation group (UDCG) based on PAM and rectangular QAM constellations. With this new concept, a modulation division (MD) transmission scheme is developed for the considered MISO BC. The proposed MD scheme enables each receiver to uniquely and efficiently recover their desired signals from the superposition of mutually interfering cochannel signals in the absence of noise. Using max-min fairness as a design criterion, the optimal transmitter beamforming problem is solved in a closed-form for two-user MISO BC. Then, for a general case with more than two receivers, a user-grouping based beamforming scheme is developed, where the grouping method, beamforming vector design and power allocation problems are addressed by employing weighted max-min fairness. Then, we consider an uplink massive single-input and multiple-output (SIMO) network consisting of a base station (BS) and several single-antenna users. To recover the transmitted signal matrix of all the users when the antenna array size is large, a novel multi-user space-time modulation (MUSTM) scheme is proposed for the considered network based on the explicit construction of QAM uniquely-decomposable constellation groups (QAM-UDCGs). In addition, we also develop a sub-constellation allocation method at the transmitter side to ensure the signal matrix is always invertible. In the meanwhile, an efficient training correlation receiver (TCR) is proposed which calculates the correlation between the received sum training signal vector and the sum information carrying vector. Moreover, the optimal power allocation problems are addressed by maximizing the coding gain or minimizing the average SEP of the received sum signal under both average and peak power constraints on each user. The proposed transmission scheme not only allows the transmitted signals with strong mutual interference to be decoded by a simple TCR but it also enables the CSI of all the users to be estimated within a minimum number of time slots equal to that of the users. Comprehensive computer simulations are carried out to verify the effectiveness of the proposed uniquely decomposable space-time modulation method in various network topologies and configurations. Our modulation division method will be one of the promising technologies for the fifth generation (5G) communication systems. / Dissertation / Doctor of Philosophy (PhD)

Satellite constellation design has been a well-studied problem since the beginning of the space age. In recent years new concepts and approaches tried to solve it with fewer satellites whilst guaranteeing coverage to the areas of interest, whether globally or regionally. This thesis introduces a novel approach based on the repeating ground track concept. It then links and converts the constellation design problem to a Set Cover problem. Although it is NP-hard, the Greedy Algorithm is capable to approximate the solution in a polynomial time with a logarithm ratio. An application of the non-symmetric strategy is illustrated with in 36 different scenarios, where altitude, sensor swath and time requirement are varied. In addition to that, a comparison with the Walker constellation on 6 scenarios is analyzed and discussed. In most cases the non-symmetric strategy produces constellations with significantly less satellites required. / Satellitkonstellationsdesign har varit ett väl studerat problem sedan början av rymdåldern. Under de senaste åren har nya koncept och tillvägagångssätt försökt lösa det med färre satelliter samtidigt som de garanterar täckning till intresseområdena, globalt eller regionalt. Detta examensarbete introducerar ett nytt tillvägagångssätt baserat på konceptet med återkommande markspår. Den länkar sedan och konverterar konstellationsdesignproblemet till ett Set Cover-problem. Även om problemet är NP-hårt, är den giriga algoritmen kapabel att approximera lösningen under polynomtid med ett logaritmförhållande. En tillämpning av den icke-symmetriska strategin illustreras med i 36 olika scenarier, där höjd, sensorsvep och tidsbehov varieras. Utöver det analyseras och diskuteras en jämförelse med Walker-konstellationen på 6 scenarier. I de allra flesta fall producerar den icke-symmetriska strategin konstellationer med betydligt färre satelliter.