Дисертації з теми "Communications cellules"
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1
Sigillo, Francesco. "Importance des cytokines dans les communications entre les cellules de Sertoli et les cellules germinales dans le testicule de rat." Lyon 1, 1999. http://www.theses.fr/1999LYO1T136.
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2
Mesnil, Marc. "Rôle possible des communications jonctionnelles intercellulaires dans la cancérogénèse." Lyon 1, 1989. http://www.theses.fr/1989LYO1T050.
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3
Houeto, Fabien. "Affectation de cellules à des commutateurs dans les réseaux de communications personnelles." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape7/PQDD_0017/MQ48857.pdf.
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4
Laffont, Benoit. "Étude du rôle extra-plaquettaire des microARN : implication des microparticules de plaquettes dans les communications intercellulaires." Doctoral thesis, Université Laval, 2015. http://hdl.handle.net/20.500.11794/26138.
Повний текст джерелаАнотація:
Tableau d’honneur de la Faculté des études supérieures et postdoctorales, 2015-2016Les plaquettes sanguines contiennent une quantité abondante et diversifiée de microARN, qui sont de petits ARN non-codants d’une vingtaine de nucléotides de long capables de réguler l’expression des gènes de manière post-transcriptionnelle et séquence spécifique. Suite à leur activation, les plaquettes libèrent des microparticules (MPs), qui contiennent du matériel génétique issu de leur cellule d’origine et susceptible d’être transmis à une autre cellule afin d’y exécuter une fonction biologique. Durant mes travaux de thèse, j’ai étudié le rôle extra-plaquettaire des microARN et la capacité des MPs de plaquettes à participer aux communications intercellulaires. Les résultats que j’ai obtenus démontrent que les plaquettes activées à la thrombine libèrent la majorité de leur contenu en microARN dans les MPs, notamment miR-223. Les MPs sont internalisées par les cellules endothéliales HUVEC, et y délivrent leur contenu en miR-223. De plus, les MPs contiennent des complexes effecteurs Argonaute 2 (Ago2)•miR-223 fonctionnels et capables de réguler l’expression d’un gène rapporteur dans les cellules cibles endothéliales. Enfin, miR-223 provenant des MPs est capable de réguler l’expression de deux gènes endogènes prédits pour être ciblés par miR-223 et présents dans les HUVEC, à la fois au niveau de l’ARN messager (ARNm) et de la protéine. Dans une deuxième étude, j’ai démontré que ce phénomène n’est pas exclusif aux cellules endothéliales et qu’il peut également se produire avec les macrophages primaires humains. Les MPs sont effectivement internalisées par les macrophages et y délivrent leur contenu en miR-126-3p, qui y est fonctionnel et y régule l’expression d’un gène rapporteur et de gènes endogènes. De plus, l’internalisation des MPs induit une modification du transcriptome des macrophages receveurs, avec 66 microARN et 653 ARN codants ou non codants dont les profils d’expression sont modifiés. Ces changements sont accompagnés d’une diminution de la sécrétion de cytokines et de chimiokines, et d’une augmentation de la capacité de phagocytose par les macrophages. Mes travaux de doctorat démontrent que les microARN véhiculés par les MPs plaquettaires sont impliqués dans la reprogrammation de l’expression des gènes et des fonctions des cellules les internalisant, reflétant ainsi la complexité des communications intercellulaires.
Blood platelets contain an abundant and diverse array of microRNAs, which are small non-coding RNAs of ~20 nucleotides involved in post-transcriptional regulation of gene expression in a sequence-specific manner. Upon activation, platelets release microparticles (MPs) containing genetic materials from their parental cells that may be transferred to, and exert potent biological effects in, recipient cells. During my PhD thesis, I studied the extra-platelet role of microRNAs, and the ability of platelet-derived MPs to mediate cell-to-cell communications. The results that I obtained demonstrate that thrombin-activated platelets preferentially release their microRNA content in MPs, including miR-223. MPs can be internalized by human umbilical vein endothelial cells (HUVEC), to which they transfer their miR-223 content. Moreover, platelet MPs contain functional effector Argonaute 2 (Ago2)•miR-223 complexes that are capable of regulating expression of a reporter gene in recipient HUVEC. Finally, platelet MP-derived miR-223 could regulate expression of two endogenous genes in recipient HUVEC, both at the mRNA and protein levels. In a second study, I demonstrated that this process is not exclusive to endothelial cells, and could take place also in primary human macrophages. Following their internalization by macrophages, MPs deliver functional miR-126-3p, which regulated expression of both a reporter gene and endogenous genes. Furthermore, MP internalization modified the transcriptome of recipient macrophages, with 66 microRNAs and 464 coding and non-coding RNAs that are differentially expressed. These changes are associated with a reduced secretion of cytokines and chemokines, and a marked increase in the phagocytic capacity of macrophages. My doctoral work demonstrate that platelet-derived microRNAs transfered by MPs are involved in reprograming recipient cells’ gene expression and functions, which illustrate the growing complexity of cell-to-cell communications.
5
BOURDON, VERONIQUE. "Etablissement et caracterisation d'une lignee de cellules de sertoli pour l'etude des communications intercellulaires dans le testicule." Nice, 1997. http://www.theses.fr/1997NICE5206.
Повний текст джерелаАнотація:
L'analyse de la fonction sertolienne se heurte a la complexite des interactions existantes dans le testicule et aux problemes lies aux cultures primaires. Pour la plupart d'entre elles, les lignees de cellules de sertoli sont issues d'animaux immatures et/ou ont un phenotype proche de cellules transformees. Nous avons utilise des familles de souris transgeniques exprimant l'antigene grand t du virus polyome (pylt). L'oncogene plt qui code pour pylt induit l'immortalisation cellulaire, les cellules se multiplient en culture et ont des caracteristiques de cellules normales et n'evoluent pas vers un phenotype de cellules transformees. Une lignee, 42gpa9, a ete etablie a partir de cellules de sertoli issues de testicules histologiquement et fonctionnellement normaux de males pylt adultes. Elle est maintenue en culture depuis trois ans. Les cellules possedent des caracteristiques de cellules normales : inhibition de contact, croissance sur support solide, cytosquelette d'actine organise en fibres de tension. Elles sont morphologiquement semblables aux cellules de sertoli et expriment de nombreux caracteres sertoliens (transferrine, sgp-2, scf, tpa) sans exprimer de marqueurs leydigiens ou germinaux (3-hsd, ldh-x). Les cellules de la lignee 42gpa9 ont conserve une intense activite phagocytosique et repondent a la fsh. Elles forment a confluence des complexes jonctionnels, comparables a ceux observes in vivo, composes de jonctions serrees et communicantes. In situ, les cellules de sertoli sont soumises a divers types de regulation (endocrine, et locales). La lignee 42gpa9 nous a servi de modele pour etudier deux formes de regulations locales, d'une part, l'influence de la phagocytose sur le systeme activateur du plasminogene sertolien et d'autre part d'apprehender le role des jonctions communicantes et de leurs proteines contitutives, les connexines, dans la communication cellule a cellule au sein de l'epithelium seminifere.
6
Jaffredo, Manon. "Communications intercellulaires dynamiques au sein des îlots pancréatiques analysées par multi-electrode arrays : rôles physiologiques et applications biotechnologiques en diabétologie." Thesis, Bordeaux, 2021. http://www.theses.fr/2021BORD0120.
Повний текст джерелаАнотація:
Les îlots pancréatiques sont le principal capteur de glycémie et intègrent toutes les informations métaboliques et hormonales pour adapter en temps réel la sécrétion des hormones, telles que l'insuline par les cellules β majoritaires et le glucagon par les cellules α. Dans le diabète de type 1 (DT1) les cellules β sont détruites par réaction auto-immune et dans le DT2 la masse de cellules β, la fonction et le réseau intra-îlot sont altérés. La réactivité de ces micro-organes est due à leurs propriétés électriques, encodant rapidement l’information, et aux communications entre cellules β/β et β/non-β. Cependant des outils non-invasifs à haute résolution et long terme pour les analyser manquent. L’électrophysiologie extracellulaire par multi-electrode arrays (MEAs) le permet en mesurant des signaux cellulaires mais aussi multicellulaires (SPs) dus aux couplages entre cellules β. J’ai donc utilisé les MEAs (i) pour explorer la physiologie/physiopathologie des îlots et (ii) pour des applications en diabétologie. J’ai montré que la cinétique biphasique de la sécrétion d’insuline était encodée par les SPs avec des changements dynamiques de couplages entre cellules β. Une hormone intestinale importante (GLP-1) augmente la 2de phase alors que des conditions diabétiques (glucotoxicité) réduisent la 1re. La réponse aux nutriments requiert de plus la coopération avec les cellules α, car leur suppression (modèle inductible GluDTR) réduit l’activité basale et la 2de phase des cellules β en présence d’un mélange physiologique d’acides aminés. J’ai également caractérisé électrophysiologiquement les cellules β humaines dérivées de cellules souches pluripotentes induites (iPSC), déterminé leurs couplages, établi leur contrôle qualité et démontré l’impact fonctionnel d’une mutation d’intérêt (ZnT8) éditée par CRISPR/Cas9. Un contrôle qualité fonctionnel des îlots humains avant greffe chez des patients DT1 a également été réalisé et comparé aux résultats cliniques. Enfin, mes enregistrements de SPs analysées par microélectronique en temps réel ont permis de valider un modèle in silico de biocapteur dans un simulateur de référence de patients DT1. En conclusion, mes travaux montrent (i) l’importance des communications intra-îlots dans leur adaptation physiologique dynamique, (ii) et que l’exploitation des SPs ouvre des applications allant du pancréas artificiel à la thérapie cellulaire personnaliséePancreatic islets are the main sensor of glycaemia and they integrate all the metabolic and hormonal inputs to adapt in real time the secretion of hormones such as insulin by β cells and glucagon by α cells. In type 1 diabetes (T1D) β cells are destroyed by immune attack, and in T2D, β cell mass, function and the intra-islet network are altered. The islet micro-organs are highly reactive due to their electrical properties encoding rapid information and due to intercellular communications between β cells and β/non-β cells. Nevertheless, non-invasive, high resolution and long-term approaches for analysis are still lacking. Extracellular electrophysiology with multi-electrode arrays (MEAs) allows this analysis of islets by measuring both cellular as well as multicellular signals (SPs) due to β cell coupling. During my PhD, I used MEAs (i) to explore islet physiology/pathophysiology and (ii) for biotechnological applications in diabetology. I have shown that biphasic kinetics of insulin secretion are encoded by SPs through dynamic changes in β cell coupling. An important intestinal hormone (GLP-1) increases the 2nd phase of β-cell activity while diabetic conditions (glucotoxicity) reduce the 1st phase. Islet responses to nutrients also require α/β cell cooperation since α cell ablation in the inducible GluDTR mice model reduced both the basal and 2nd phase of β cell activity generated by glucose and a physiological mix of amino acids. I have also performed the electrophysiological characterization of human β cells derived from induced pluripotent stem cells (iPSC), determined their coupling, established their quality control and shown the functional impact of a mutation of interest (ZnT8) edited by CRISPR/Cas9. A functional quality control of human islets prior to transplantation in T1D patients was also performed for correlations with clinical data. Finally, my SP recordings analyzed in real time by microelectronics has contributed to validate an in silico model of biosensor in a FDA-approved simulator of T1D patients. In conclusion, my work demonstrates (i) the role of intra-islet communications in the dynamic physiological adaptation of these micro-organs, (ii) and that detailed characterization of SPs opens new applications from artificial pancreas to personalized cell therapy
7
Milon, Marie-Anne. "Modélisation de cellules déphaseuses environnées : Application à l'analyse de réseaux réflecteurs imprimés." Rennes, INSA, 2001. http://www.theses.fr/2007ISAR0022.
Повний текст джерелаАнотація:
Le contexte dans lequel s'inscrit ce travail est celui des réseaux réflecteurs plans imprimés passifs au rayonnement directif et transversal. Ce travail de thèse s'attache à analyseret modeliser en détails le fonctionnement de cellules et de réseaux réflecteurs existants et propose de nouveaux outils pour investiguer les effets du couplage et ceux de la réflexion spéculaire sur le plande l'antenne. On propose ici d'appliquer la FDTD a la simulation de ces cellules élémentaires, en tenan compte de l'effet de leur environnement. Une nouvelle approche pour la modélisation des cellulesde réseau réflecteur est présentée et validée en particulier, cette approche permet de prendre en compte et de caractériser les effets liés à la réflexion spéculaire et au couplage mutuel. En outre, ce travail propose une amélioration de la rétro-simulation du réseau complet afin de mieux en estimer le rayonnement et prend désormais en compte l'illumination réelle de la source primaire utiliséeThis study is focusing on flat passive microstrip reflectarrays with brodadside and directive radiation. This thesis is dedicated to both analyse and modelize the unitary cell behaviour of existing reflectarrays. New simulation tools are proposed to study mutual coupling and specualr reflection effects. The FDTD analysis of a unitary reflectarray cell is appllied to take into account environment effects. A new approcah to analyse reflectarray cell is presented and validated. This approach considers the actual mutual coupling for a realistic configuration with non identical cells and also characterise the specular reflection effect. Moreover , this work provides an improvement of the whole reflectarray simlulation, which accounts for the real illumination of the primary source
8
Fauquier, Teddy. "LES CELLULES FOLLICULOSTELLAIRES : UNITES FONCTIONNELLES D'UNE VOIE DE COMMUNICATION A LONGUE DISTANCE DANS L'HYPOPHYSE ANTERIEURE." Phd thesis, Université Montpellier II - Sciences et Techniques du Languedoc, 2001. http://tel.archives-ouvertes.fr/tel-00770829.
Повний текст джерелаАнотація:
L'hypophyse antérieure assure une interface endocrine entre le cerveau et les organes périphériques. En effet, cette glande sécrète de manière pulsatile ses différentes hormones dans la circulation générale sous l'influence de facteurs hypothalamiques déversés épisodiquement dans le système porte de l'éminence médiane. Toutefois, l'influence hypothalamique ne saurait à elle seule expliquer l'harmonisation des sécrétions des cellules d'un même type endocrine, qui sont distribuées de manière hétérogène au sein du parenchyme. Il existe sans doute des mécanismes permettant de coordonner l'activité des cellules endocrines à l'échelle de la glande entière. Au cours de cette thèse, nous avons montré la présence d'un mécanisme de communication intra-hypophysaire permettant un transfert rapide d'information au sein d'un réseau de cellules non-endocrines, les cellules folliculostellaires (FS). Ce travail réalisé sur des tranches épaisses d'hypophyse de rat, modèle qui maintient intacte l'architecture cordonale du tissu, a permis de mettre en évidence l'excitabilité membranaire des cellules FS, propriété jusqu'alors inconnue. Cette excitabilité sert de base à l'initiation de vagues calciques, qui peuvent se propager rapidement via des jonctions gap à des régions éloignées de la glande. Nous avons également étudié la libération d'interleukine-6 (IL-6) par les cellules FS. Cette cytokine est connue pour stimuler l'ensemble des sécrétions hormonales hypophysaires. La production d'IL-6 est stimulée par le PACAP. Ce neuropeptide semble agir directement au niveau du gène, et son effet dépend de l'état des communications intercellulaires au sein du réseau. Les cellules FS pouvant répondre à des stimuli d'origine centrale et périphérique, ainsi que dialoguer avec les cellules endocrines, l'ensemble de ces résultats montre que le réseau de cellules FS pourrait fournir un mécanisme efficace qui coordonnerait le fonctionnement de la glande en fonction des différents états physiologiques
9
Adane, Yacine. "Caractérisation inverse de sources pour l'évaluation de l'exposition humaine aux ondes électromagnétiques émises par les antennes de station de base." Paris 6, 2004. http://www.theses.fr/2004PA066348.
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10
Caicedo, Andrès. "Communication cellule-cellule : transfert de mitochondries provenant des cellules souches/stromales mesenchymateuses (CSM) vers des cellules cancereuses." Thesis, Montpellier 1, 2013. http://www.theses.fr/2013MON1T036.
Повний текст джерелаАнотація:
Au début de ma thèse, je me suis intéressé aux processus qui sous-tendent la communication cellulaire et plus spécifiquement les interactions cellule-cellule. Pourquoi une cellule établit-elle un contact spécifique avec une autre cellule ? Comment les cellules répondent-elles à cette interaction et quels en sont les effets ? J'ai utilisé comme modèle d'étude l'interaction entre les cellules souches/stromales mésenchymateuses (CSM) et des lignées de cancer du sein. L'objectif de mon travail a été d'analyser les mécanismes de ces interactions entre CSM et cellules cancéreuses et d'en évaluer les effets sur les fonctions des cellules cancéreuses. En effet, des mécanismes de recrutement des CSM aux sites tumoraux ont été décrits avec des effets sur la progression tumorale, ce qui ouvre par ailleurs des perspectives pour de nouvelles approches thérapeutiques. J'ai tout d'abord développé un système expérimental de microscopie confocale en temps réel pour observer le type d'interaction qui est produit entre les CSM humaines et les cellules de carcinomes mammaires MDA-MB-231 et MCF7. J'ai constaté la formation dynamique de structures tubulaires entre les deux types cellulaires et, de façon surprenante, le passage des mitochondries des CSM vers les cellules cancéreuses. En un deuxième temps, j'ai utilisé un système d'invasion dans une matrice 3D de collagène, que nous avons adapté à la coculture, afin d'observer les effets de l'interaction des MDA-MB-231 avec les CSM. En accord avec la littérature, nous avons constaté une augmentation du pouvoir invasif des cellules cancéreuses, effet qui pouvait être lié au transfert des mitochondries provenant des CSM. Pour répondre à cette question, j'ai mis au point un protocole pour transférer spécifiquement des mitochondries, isolées à partir de cellules, vers d'autres cellules. Ce protocole, exploité dans ce manuscrit pour le transfert de mitochondries de CSM vers les cellules cancéreuses MDA-MB-231, peut être transposé à d'autres types cellulaires et fait l'objet d'une demande de brevet. Nos données indiquent que l'acquisition de mitochondries de CSM par les cellules cancéreuses modifie leurs propriétés fonctionnelles et augmente leur capacité de prolifération et d'invasion. Concernant leur activité métabolique, on observe une augmentation de leur respiration mitochondriale et de leur production d'ATP. Nos données préliminaires suggèrent aussi une augmentation de l'expression transcriptionnelle d'enzymes impliquées dans la synthèse des lipides et l'oxydation des acides gras. Ces données, générées grâce au protocole de transfert artificiel de mitochondries mis au point, montrent pour la première fois que les mitochondries des CSM peuvent majorer certaines propriétés cellulaires liées à la progression tumorale, comme la prolifération et l'invasion, et contribuer à une reprogrammation métabolique des cellules cancéreuses. Elles s'intègrent au rôle proposé par la communauté scientifique pour les CSM dans le microenvironnement tumoral. La technique de transfert artificiel de mitochondries nous permettra de répondre à d'autres questions restées ouvertes, comme le rôle possible des mitochondries des CSM dans les résistances développées par les tumeurs vis-à-vis des agents anti-cancéreux. Le protocole de transfert de mitochondries développé au laboratoire constitue une technique de choix et offre de nombreux avantages comparativement à d'autres techniques comme la micro-injection et la génération des hybrides cytoplasmiques. Sa mise en œuvre est en effet simple et reproductible et permet de traiter une grande quantité de cellules. Cette méthode permet d'envisager de nombreuses perspectives et applications dans le domaine de la reprogrammation métabolique, comme par exemple de restaurer les capacités d'une cellule dysfonctionnelle par le transfert de mitochondries issues d'une cellule saine et « métaboliquement active »At the beginning of my thesis, I was interested in the process involved in cell communication, more specifically in cell-to-cell interactions. Why does a cell specifically establish contacts with another one, how do cells respond to these interactions and what are the effects? As a model to answer these questions, I studied the interactions between MSCs and two breast cancer cell lines. The study of the communications between MSCs and tumor cells is an alternative to explore and understand tumor progression. MSC recruitment to the tumor is shown to favor the progression of the disease. The mechanisms of this dialogue are multiple and are the object of a great number of studies that aim at finding new therapeutic approaches. The objective of this work was to analyze the interactions between MSCs and cancer cells and evaluate the potential effects of this communication in tumor progression. First, I developed an experimental system of real time confocal microscopy in order to observe the interaction produced between MSCs and the breast carcinoma MDA-MB-231 and MCF-7 cells. I noticed the dynamic formation of tubular structures between the two different cell types and, surprisingly, the passage of mitochondria from MSCs to the cancer cells. Second, we used a 3D system of cell invasion in a collagen matrix, which we adapted for the coculture, in order to observe the effects of the interactions between the MDA-MB-231 and MSCs. In agreement with the literature, we observed an increase in the migratory potential of the cancer cells, an effect that could be linked to the transfer of mitochondria from MSCs to the cancer cells. To answer this question, I set up a protocol to specifically transfer to the cancer cells mitochondria isolated from the MSCs and test directly the functional consequences for the cancer cells. This protocol can be used to transfer mitochondria, not only from MSCs but also from other cells. This method is currently submitted to a patent process. Our results show that the transfer of MSC mitochondria to the cancer cells modifies cancer cells functional properties and increase their invasive and proliferative capacities. Concerning the metabolic activity, we noticed an increase in mitochondrial respiration and ATP production. We also observed an increase in the transcription level of enzymes related to the lipid synthesis and fatty acid oxidation. The results generated with this new protocol of mitochondria transfer show, for the first time, that mitochondria originating from MSCs can improve cellular capacities linked to the tumor progression. The role proposed by the scientific community for the interactions of MSCs with the tumor cells fits with the data generated in our work. Several questions remain open. In particular, could the transfer of mitochondria from MSCs to the cancer cells contribute to the acquisition of resistance to anti-cancer agents observed in patients? The protocol of transfer of mitochondria that we developed in the laboratory is a technique of choice and offers many advantages over other techniques such as microinjection and cytoplasmic hybrids; its implementation is simple and reproducible and can target large numbers of cells. This method opens numerous perspectives and potential applications such as the study of metabolic reprogramming. Thus, we could consider restoring the activity of dysfunctional cells by transferring mitochondria from “metabolically active” or healthy cells. In the long term, one of the applications could be transferring healthy or genetically modified mitochondria to zygotes carrying mitochondrial DNA mutations, in order to treat pathologies like infertility, neuro-degenerative diseases, cancer and premature aging
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Rodier, Geneviève. "Effet et mode d'action de la glicentine et de l'oxyntomoduline sur les cellules musculaires lisses gastriques (doctorat : systeme de communications intercellulaires en endocrinologie)." Aix-Marseille 2, 1998. http://www.theses.fr/1998AIX2660U.
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Savard, Anne. "Codage pour les communications coopératives : Codage de source distribué et canaux à relais." Thesis, Cergy-Pontoise, 2015. http://www.theses.fr/2015CERG0774/document.
Повний текст джерелаАнотація:
L'augmentation du trafic sur les réseaux sans fil ne permet plus de traiter les données en utilisant les protocoles standard des réseaux filaires, qui sont eux sans interférences. Ainsi, les nœuds des réseaux sans fil doivent coopérer en exploitant les corrélations inhérentes à la proximité des utilisateurs afin d'exploiter au mieux la capacité d'un tel réseau.Dans cette thèse, nous considérons tout d'abord le problème de codage de source avec information adjacente compressée. Le nœud coopératif, ayant accès à un signal corrélé avec celui de la source, peut en envoyer une version compressée au destinataire sur un lien indépendant, permettant d'économiser du débit sur le lien principal. En utilisant une caractérisation des cellules de Voronoi du quantificateur utilisé, nous avons pu améliorer un algorithme de décodage itératif basé sur des codes LDPC.La seconde partie de la thèse traite des problèmes de codage de canal, où les nœuds coopératifs sont des relais. L'exemple le plus simple d'une telle communication est le canal à relais, où un relais aide à la communication entre la source et la destination. Alors que dans le problème de codage de source, le canal de corrélation entre la source et le nœud coopératif est fixé, dans le codage de canal, la question est de savoir quelle opération effectuer au relais. Tout d'abord, nous considérons un problème quelque peu dual au problème de codage de source avec information adjacente compressée, en considérant des bruits corrélés au relais et la destination. Puis, nous étudions des bornes sur la capacité et des débits atteignables pour deux extensions du canal à relais, le canal à relais bidirectionnel avec des bruits corrélés au relais et aux destinations, où deux sources échangent leurs données avec l'aide d'un relais, et le canal multidirectionnel avec liens directs (qui modélisent la proximité des utilisateurs), où les utilisateurs sont regroupés dans des clusters et échangent leurs données localement au sein d'un même cluster avec l'aide d'un relaisThe current wireless data traffic growth cannot be handled by classical multi-hop network protocols as in interference-free wired networks, thus it has been recognized that network nodes need to cooperate in order to take advantage of source and/or channel signal correlations, which is needed to achieve fundamental capacity limits.This thesis first considers a cooperative source coding problem, namely binary source coding with coded side information (CoSI): the helper node has access to a signal that is correlated with the source and may send a compressed version on a separate link to the destination, thus rate can be saved on the main source-destination link. Using a characterization of the Hamming-space Voronoi regions of the quantizer at the helper node, an improved practical scheme based on LDPC codes is proposed.The second part of the thesis considers cooperative channel coding, where helper nodes are relays. The simplest example of such a communication is the relay channel, in which a relay node helps the source to send its message to the destination. Whereas in the source coding problem, the correlation between source and side information is given, in channel coding, the main question is to find the best relaying operation. First, a somewhat dual problem to source coding with CoSI is studied, by considering correlated noises at the relay and destination. Then, various extensions of the relay channel are characterized using upper bounds on capacity and achievable rates: the two-way relay channel with correlated noises at the relay and destinations, where two sources wish to exchange their data with the help of a relay, and the multiway relay channel with direct links, where users, grouped into fully connected clusters (users in a cluster can overhear each others' messages), wish to exchange their messages locally within a cluster with the help of one relay
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De, Domenico Antonio. "Technique de gestion de ressources radios pour l'amélioration de l'efficacité énergétique dans les réseaux cellulaires hétérogènes." Thesis, Grenoble, 2012. http://www.theses.fr/2012GRENM012/document.
Повний текст джерелаАнотація:
Les communications sans fil prolifèrent dans presque chaque aspect de la société humaine : puissants ‘smart-phones' et ‘tablets', accès haut débit sans fil, et communications ‘machine-to-machine' ont généré des volumes de trafic de données imprévisibles quelques années en arrière. Dans ce nouveau paradigme, l'industrie des télécommunications se doit de garantir à la fois la durabilité économique des communications sans fil à large bande ainsi que la qualité de son service. En outre, il y a une forte incitation sociale à réduire les émissions de C02 duent aux communications mobiles, qui a augmenté notamment dans la dernière décennie. Dans ce contexte, l'intégration des ‘femtocells' dans les réseaux cellulaires est une solution à faible coût pour offrir une qualité de service élevée et en même temps de décharger le réseau macrocellule. Cependant, le déploiement massif et chaotique des points d'accès femtocell et leurs opérations non coordonnées peuvent conduire à une augmentation de l'interférence co-canal. De plus, un nombre élevé de cellules faiblement chargées augmente la consommation énergétique du réseau. Dans cette thèse, nous avons étudié les effets du déploiement de femtocells sur l'efficacité énergétique du réseau cellulaire. Par ailleurs, nous investiguons sur les mécanismes d'adaptation pour les réseaux des femtocells comme un moyen pour améliorer l'efficacité des communications mobiles. Notre objectif est de répondre dynamiquement à la demande des ressources afin de limiter la consommation d'énergie moyenne et l'interférence co-canal, tout en garantissant la qualité de service. Nous profitons du contexte inhabituel de communication ‘femtocellulaire' pour proposer des mécanismes d'allocation des ressources et des systèmes de gestion de réseau qui coordonne l'activité des points d'accès, la consommation d'énergie et de la couverture. Les résultats des simulations montrent que nos propositions améliorent l'efficacité énergétique et les performances perçues par les utilisateurs du système dans les réseaux ‘femtocellulaires' coopératives et autonomesWireless communication proliferates into nearly each aspect of the human society, driving to the exponential growth in number of permanently connected devices. Powerful smart-phones and tablets, ubiquitous wireless broadband access, and machine-to-machine communications gen- erate volumes of data traffic that were unpredictable few years back. In this novel paradigm, the telecommunication industry has to simultaneously guarantee the economical sustainability of broadband wireless communications and users' quality of experience. Additionally, there is a strong social incentive to reduce the carbon footprint due to mobile communications, which has notably increased in the last decade. In this context, the integration of femtocells in cellular networks is a low-power, low-cost solution to offer high data rates to indoor customers and simultaneously offload the macrocell network. However, the massive and unplanned deployment of femtocell access points and their uncoordinated operations may result in harmful co-channel interference. Moreover, a high number of lightly loaded cells increases the network energy consumption. In this thesis, we investigate the effects of femtocells deployment on the cellular network energy efficiency. Moreover, we look into adaptive mechanisms for femtocell networks as a means to pave the way towards agile and economically viable mobile communications. Our goal is to dynamically match resource demand and offered capacity in order to limit the average power consumption and co-channel interference while guaranteeing quality of service constraints. We take advantage of the unusual communication context of femtocells to propose resource allocation and network management schemes that coordinate the access points activity, power consumption, and coverage. Simulation results show that our proposals improve system energy efficiency and users' performance in both networked and stand-alone femtocell deployment scenarios
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Idres, Saïd. "Communications de type paracrine dans la glande interrénale des amphibiens : production locale de la sérotonine et mécanisme d'action de l'indolamine sur la stéroïdogénèse." Rouen, 1990. http://www.theses.fr/1990ROUES036.
Повний текст джерелаАнотація:
L'interrénale des amphibiens est composée de cellules chromaffines et stéroïdogènes qui peuvent communiquer par un mécanisme paracrine. Notre travail a porté sur: i) l'action et le mécanisme d'action de la sérotonine (5-HT) et ii) l'origine de l'amine contenue dans les cellules chromaffines. La technique de périfusion couplée aux dosages radioimmunologiques des stéroïdes nous a permis de montrer que la 5-HT est un puissant facteur stimulateur de la sécrétion de corticostérone et d'aldostérone. L'infusion de 5-HT sur les cellules dispersées provoque une forte et rapide augmentation de la stéroïdogénèse suggérant un effet direct de l'amine sur les cellules corticosurrénaliennes. Une approche pharmacologique a été utilisée pour caractériser les récepteurs mis en jeu dans la réponse de la surrénale à la 5-HT. Nos résultats indiquent que l'effet de la 5-HT n'est pas médié via les récepteurs classiques 5-HT1, 5-HT2 et 5-HT3. En revanche, nous montrons l'intervention d'un récepteur de type 5-HT4 couplé positivement à l'adénylate cyclase dans le mécanisme d'action de la 5-HT sur la surrénale. Nous avons également recherché l'origine de la 5-HT présente dans les granules de sécrétion des cellules chromaffines de la surrénale. Nos résultats démontrent l'existence d'une synthèse locale de 5-HT, à partir des précurseurs Trp et 5-HTP dans l'interrénale de grenouille. En conclusion, la 5-HT, produite et libérée par les cellules chromaffines de la surrénale d'amphibien, stimule la stéroïdogénèse par un mécanisme paracrine. Cet effet de la 5-HT est médié par les récepteurs 5-HT4 couplés à l'adénylate cyclase
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Bost, Pierre. "Decoding cellular communications and interactions between immune cells by using single-cell approaches." Electronic Thesis or Diss., Sorbonne université, 2020. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2020SORUS020.pdf.
Повний текст джерелаАнотація:
Les communications cellulaires sont indispensables au bon fonctionnement des organismes multicellulaires, notamment pour s’adapter à un environnement changeant en permanence. Les cellules du système immunitaire n’échappent pas à cette règle mais les interactions entre cellules immunitaires restent peu connues et compliquée à étudier. La récente apparition des technologies de séquençage dites ‘cellules uniques’ représente une opportunité unique pour étudier ces communications. Dans cette thèse, différentes approches expérimentales et analytiques ont été développées pour étudier ces communications à une échelle de cellules uniques. Ces stratégies ont ensuite été appliquées à différents contextes pathologiques, incluant le COVID-19, la maladie d’Alzheimer ou une immunisation par des pathogènes inactivés, et ont permis d’identifier des voies de communications cellulaires jusqu’ici inconnues ou mal comprises. Néanmoins, l’efficacité de ces approches est limitée par l’absence d’informations sur la localisation des cellules et des travaux supplémentaires intégrant ce genre de données est essentiel pour aller plus loin dans la dissection des communications entre cellules immunitairesCellular communications are essential to the proper functioning of multi-cellular organisms, particularly in order to adapt to a constantly changing environment. The cells of the immune system are no exception to this rule, but the interactions between immune cells remain little known and complicated to study. The recent emergence of 'single cell' sequencing technologies represents a unique opportunity to study these communications. In this thesis, different experimental and analytical approaches have been developed to study these communications on a single cell scale. These strategies were then applied to different disease contexts, including COVID-19, Alzheimer's disease or immunisation with inactivated pathogens, and identified previously unknown or poorly understood cellular communication pathways. However, the effectiveness of these approaches is limited by the lack of information on cell location and further work integrating such data will be essential to go further in the dissection of immune cell communications
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Schreyer, Edwige. "Rôle du récepteur des androgènes dans les communications cellulaires au sein du cancer de la prostate." Thesis, Strasbourg, 2018. http://www.theses.fr/2018STRAJ098.
Повний текст джерелаАнотація:
La castration représente le traitement de référence du cancer de la prostate à un stade avancé. Cependant, la plupart des patients rechute du fait notamment de l’émergence de variants tronqués constitutivement actifs du récepteur des androgènes (RA). Le microenvironnement tumoral, en particulier les fibroblastes associés au cancer (CAFs), favorisent largement la progression tumorale. Ils sont très hétérogènes et dérivent de plusieurs types cellulaires dont les cellules souches mésenchymateuses (MSCs). Afin de mettre à jour l’impact des variants du RA sur le microenvironnement tumoral, mon projet de thèse a porté sur l’étude des effets de ces variants du RA sur la différenciation des MSCs en CAFs. Les résultats obtenus m’ont permis de démontrer un impact positif du variant RA Q641X sur l’expression du facteur de différenciation VEGF par les cellules tumorales, ainsi que sur l’expression des marqueurs de différenciation en CAFs FSP-1, CXCL12, PDGFR-β, ainsi que VEGF, au niveau des MSCs. Ces données suggèrent que le variant RA Q641X est capable d’induire la différenciation des MSCs en CAFs, soulignant ainsi l’importance de développer de nouvelles stratégies thérapeutiques ciblant ces variants du RAAndrogen ablation therapy remains the most common treatment for patients with advanced prostate cancer. However, most patients will relapse due to the emergence of truncated constitutively active androgen receptor (AR) variants. The tumor microenvironment is another necessary feature driving prostate cancer progression. Cancer associated fibroblasts (CAFs) are the major specialized stromal cells that favor tumor progression. These cells are very heterogeneous and derive from several other cell types as mesenchymal stem cells (MSCs). In order to highlight the impact of AR variants on surrounding tumor stroma, the aim of my project was to investigate the effects of these AR variants on MSCs differentiation into CAFs. I noticed that the expression of VEGF, a CAF differentiation factor, was upregulated in tumor cells expressing AR Q641X variant. Similarly, the expression of CAF differentiation markers FSP-1, CXCL12, PDGFR-β, and VEGF was enhanced in MSCs in presence of AR Q641X variant. These data highlight an unknown property of AR Q641X variant in prostate tumor cells that is its ability to induce MSCs differentiation into CAFs, underlining the urgent need to develop novel strategies targeting these AR variants
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De, domenico Antonio. "Technique de gestion de ressources radios pour l'amélioration de l'efficacité énergétique dans les réseaux cellulaires hétérogènes." Phd thesis, Université de Grenoble, 2012. http://tel.archives-ouvertes.fr/tel-00720622.
Повний текст джерелаАнотація:
Les communications sans fil prolifèrent dans presque chaque aspect de la société humaine : puissants 'smart-phones' et 'tablets', accès haut débit sans fil, et communications 'machine-to-machine' ont généré des volumes de trafic de données imprévisibles quelques années en arrière. Dans ce nouveau paradigme, l'industrie des télécommunications se doit de garantir à la fois la durabilité économique des communications sans fil à large bande ainsi que la qualité de son service. En outre, il y a une forte incitation sociale à réduire les émissions de C02 duent aux communications mobiles, qui a augmenté notamment dans la dernière décennie. Dans ce contexte, l'intégration des 'femtocells' dans les réseaux cellulaires est une solution à faible coût pour offrir une qualité de service élevée et en même temps de décharger le réseau macrocellule. Cependant, le déploiement massif et chaotique des points d'accès femtocell et leurs opérations non coordonnées peuvent conduire à une augmentation de l'interférence co-canal. De plus, un nombre élevé de cellules faiblement chargées augmente la consommation énergétique du réseau. Dans cette thèse, nous avons étudié les effets du déploiement de femtocells sur l'efficacité énergétique du réseau cellulaire. Par ailleurs, nous investiguons sur les mécanismes d'adaptation pour les réseaux des femtocells comme un moyen pour améliorer l'efficacité des communications mobiles. Notre objectif est de répondre dynamiquement à la demande des ressources afin de limiter la consommation d'énergie moyenne et l'interférence co-canal, tout en garantissant la qualité de service. Nous profitons du contexte inhabituel de communication 'femtocellulaire' pour proposer des mécanismes d'allocation des ressources et des systèmes de gestion de réseau qui coordonne l'activité des points d'accès, la consommation d'énergie et de la couverture. Les résultats des simulations montrent que nos propositions améliorent l'efficacité énergétique et les performances perçues par les utilisateurs du système dans les réseaux 'femtocellulaires' coopératives et autonomes.
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Negi, Ansuya. "Analysis of Relay-based Cellular Systems." PDXScholar, 2006. https://pdxscholar.library.pdx.edu/open_access_etds/2668.
Повний текст джерелаАнотація:
Relays can be used in cellular systems to increase coverage as well as reduce the total power consumed by mobiles in a cell. This latter benefit is particularly useful for mobiles operating on a depleted battery. The relay can be a mobile, a car or any other device with the appropriate communication capabilities. In thesis we analyze the impact of using relays under different situations. We first consider the problem of reducing total power consumed in the system by employing relays intelligently. We find that in a simulated, fully random, mobile cellular network for CDMA (Code Division Multiple Access), significant energy savings are possible ranging from 1.76 dB to 8.45 dB.
In addition to reducing power needs, relays can increase the coverage area of a cell by enabling mobiles located in dead spots to place relayed calls. We note that use of relays can increase the useful service area by about 10% with real life scenarios. We observe that in heavy building density areas there is more need of relays as compared to low building density areas. However, the chance of finding relays is greater in low building density areas. Indeed, having more available idle nodes helps in choosing relays, so we conclude that unlike present day implementations of cellular networks, the base station should admit more mobiles (beyond the capacity of the cell) even if they are not placing calls since they can be used as relays.
One constraint of using relays is the potential to add interference in the same cell and in neighboring cells. This is particularly true if the relays are not under power control. Based on our analysis, we conclude that in interference limited systems like CDMA the relays have to be under power control otherwise we will reduce the total capacity by creating more dead spots. Thus, we believe that either the base station should be responsible to allocate relays or relays should be provided with enough intelligence to do power control of the downlink. Finally, we show how utility of data services can be increased by use of relays.
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Parand, Farivar. "Cellular optical wireless communications systems." Thesis, University of Oxford, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.270654.
Повний текст джерела
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El-Jabu, Bashir Ali R. "Cellular communications using aerial platforms." Thesis, University of Southampton, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.299380.
Повний текст джерела
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Videv, Stefan. "Techniques for green radio cellular communications." Thesis, University of Edinburgh, 2013. http://hdl.handle.net/1842/7988.
Повний текст джерелаАнотація:
This thesis proposes four novel techniques to solve the problem of growing energy consumption requirements in cellular communication networks. The first and second part of this work propose a novel energy efficient scheduling mechanism and two new bandwidth management techniques, while the third part provides an algorithm to actively manage the power state of base stations (BSs) so that energy consumption is minimized throughout the day while users suffer a minimal loss in achieved data rate performance within the system. The proposed energy efficient score based scheduler (EESBS) is based on the already existing principle of score based resource allocation. Resource blocks (RBs) are given scores based on their energy efficiency for every user and then their allocation is decided based on a comparison between the scores of the different users on each RB. Two additional techniques are introduced that allow the scheduler to manage the user’s bandwidth footprint or in other words the number of RBs allocated. The first one, bandwidth expansion mode (BEM), allows users to expand their bandwidth footprint while retaining their overall transmission data rate. This allows the system to save energy due to the fact that data rate scales linearly with bandwidth and only logarithmically with transmission power. The second technique, time compression mode (TCoM), is targeted at users whose energy consumption is dominated by signalling overhead transmissions. If the assumption is made that the overhead is proportional to the number of RBs allocated, then users who find themselves having low data rate demands can release some of their allocated RBs by using a higher order modulation on the remaining ones and thus reduce their overall energy expenditure. Moreover, a system that combines all of the aforementioned scheduling techniques is also discussed. Both theoretical and simulation results on the performance of the described systems are provided. The energy efficient hardware state control (EESC) algorithm works by first collecting statistical information about the loading of each BS during the day that is due to the particular mobility patterns of users. It then uses that information to allow the BSs to turn off for parts of the day when the expected load is low and they can offload their current users to nearby cell sites. Simplified theoretical, along with complete system computer simulation, results are included. All the algorithms presented are very straightforward to implement and are not computationally intensive. They provide significant energy consumption reductions at none to minimal cost in terms of experienced user data rate.
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Hau, Yan Kit Gary. "Multicarrier microwave amplifier for cellular communications." Thesis, University of Leeds, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.289809.
Повний текст джерела
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Thampi, Ajay. "Scalable cooperative communications in cellular networks." Thesis, University of Bristol, 2016. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.690375.
Повний текст джерелаАнотація:
In cellular networks, interference is identified as the major performance bottleneck. Attempts are made in 4G and 5G systems to address this by pooling base stations together to form a network multiple-input multiple-output (MIMO) system. Global coordination in network MIMO systems is known to be highly complex and costly. In this thesis, a scalable solution is proposed by clustering the network into groups of base stations. Interference within the cluster is mitigated by performing network MIMO based signal processing in each cluster independently. Interference between clusters is then cancelled by applying fractional frequency reuse (FFR) on a cluster scale. In FFR systems, a greater reuse factor is used for users near the cell or cluster edge since they are more prone to interference. An important problem in FFR systems is classifying the user location as either being in the centre or near the edge. The conventional technique of using a one-dimensional signal-to-interference-and-noise ratio (SINR) threshold is highly inaccurate and an improved machine learning approach based on logistic regression is proposed. It is shown to improve the accuracy to at least 80% and the cell sum rate performance is shown to be comparable to that of a system with 100% accurate classification.
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Aleswaidi, Fatemah Abdulaziz. "RACH enhancements for cellular M2M communications." Thesis, University of Bristol, 2017. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.715748.
Повний текст джерела
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Strickland, Wilburn T. "A wideband multicarrier CDMA cellular communications system." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1998. http://handle.dtic.mil/100.2/ADA356571.
Повний текст джерелаАнотація:
Thesis (M.S. in Electrical Engineering) Naval Postgraduate School, September 1998.Thesis advisor(s): Tri T. Ha, R. Clark Robertson. "September 1998." Includes bibliographical references (p. 91). Also Available online.
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Grellier, Adeline Maritie. "La communication ostéo-endothéliale : application en ingénierie du tissu osseux." Bordeaux 2, 2008. http://www.theses.fr/2008BOR21560.
Повний текст джерелаАнотація:
Le développement et le remodelage du tissu osseux dépendent d'une étroite coordination entre les cellules ostéoblastiques et ostéoclastiques, responsables de la formation et résorption osseuse respectivement, mais aussi entre les cellules osseuses et les cellules endothéliales présentes dans les vaisseaux sanguins environnants. Le but de ce travail est d'étudier la communication entre les ostéoprogéniteurs issus de la moelle osseuse (human osteoprogenitors : HOPs) et les cellules endothéliales (human ombilical cord endothelial cells : HUVECs). Cette communication ostéo-endothéliale a été analysée dans un modèle de co-culture in vitro en 2D mais aussi en 3D au sein de microsphères d'alginate qui ont été ensuite implantées in vivo dans une lésion osseuse chez la souris nude. Dans un premier temps, nous avons complété la caractérisation des HOPs. Le phénotype de ces cellules est régulé lorsqu'elles sont soumises à des contraintes mécaniques, paramètre fondamental in situ. En co-culture avec les HUVECs, le phénotype ostéoblastique des HOPs est également régulé et le VEGF (vascular endothelial growth factor) participe de façon étroite à cette régulation. Le phénotype endothélial semble lui aussi modifié en co-culture puisque la migration des HUVECs semble être à l'origine d'un réarrangement cellulaire proche de capillaires. Au sein de microsphères d'alginate cultivées in vitro, les HUVECs stimulent le phénotype ostéoblastique des HOPs. De même, la présence des HUVECs active la minéralisation induite par les HOPs dans une lésion osseuse réalisée in vivo. Cette étude montre que ces cellules sont capables de communiquer et pourraient être à la base de nouvelles stratégies d'ingénierie tissulaireBone development and remodelling are dependant on a tight cell cooperation between osteoblastic and osteoclastic cell types, responsible for bone formation and degradation, respectively. Angiogenesis is also a key process involved in these mechanisms and cell communication between osseous and endothelial cells is fundamental This work aims to study the cell communication between human osteoprogenitors (HOPs) arising from bone marrow and human endothelial cells (human umbilical cord endothelial cells : HUVECs). This osteo-endothelial communication was analysed using a well defined in vitro co-culture model in 2D but also into a 3D system into alginate microsphères which were then implanted in vivo in a bone defect in nude mice. In a first part, the HOPs were submitted to a mechanical stress which is an important parameter for the physiology of bone. Their ability to regulate their phenotype was demonstrated under shear stress. In co-culture wuth HUVECs, the phenotype was regulated and VEGF (vascular endothelial growth factor seems to be involved in this regulation. The endothelial phenotype was also regulated in co-culture since HUVECs migration led to a tubular-like cell rearrangement. Into alginate microspheres cultured in vitro, the HUVECs stimulated the osteoblastic phenotype of HOPs. Moreover, after implantation in a bone defect in vivo, the HUVECs enhanced the HOP-induced mineralization. This work shows that the cells are able to communicate and seems promising for the development of new tissue engineering strategies
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Kalalas, Charalampos. "Cellular networks for smart grid communication." Doctoral thesis, Universitat Politècnica de Catalunya, 2018. http://hdl.handle.net/10803/620760.
Повний текст джерелаАнотація:
The next-generation electric power system, known as smart grid, relies on a robust and reliable underlying communication infrastructure to improve the efficiency of electricity distribution. Cellular networks, e.g., LTE/LTE-A systems, appear as a promising technology to facilitate the smart grid evolution. Their inherent performance characteristics and well-established ecosystem could potentially unlock unprecedented use cases, enabling real-time and autonomous distribution grid operations. However, cellular technology was not originally intended for smart grid communication, associated with highly-reliable message exchange and massive device connectivity requirements. The fundamental differences between smart grid and human-type communication challenge the classical design of cellular networks and introduce important research questions that have not been sufficiently addressed so far. Motivated by these challenges, this doctoral thesis investigates novel radio access network (RAN) design principles and performance analysis for the seamless integration of smart grid traffic in future cellular networks.
Specifically, we focus on addressing the fundamental RAN problems of network scalability in massive smart grid deployments and radio resource management for smart grid and human-type traffic. The main objective of the thesis lies on the design, analysis and performance evaluation of RAN mechanisms that would render cellular networks the key enabler for emerging smart grid applications.
The first part of the thesis addresses the radio access limitations in LTE-based networks for reliable and scalable smart grid communication. We first identify the congestion problem in LTE random access that arises in large-scale smart grid deployments. To overcome this, a novel random access mechanism is proposed that can efficiently support real-time distribution automation services with negligible impact on the background traffic. Motivated by the stringent reliability requirements of various smart grid operations, we then develop an analytical model of the LTE random access procedure that allows us to assess the performance of event-based monitoring traffic under various load conditions and network configurations. We further extend our analysis to include the relation between the cell size and the availability of orthogonal random access resources and we identify an additional challenge for reliable smart grid connectivity. To this end, we devise an interference- and load-aware cell planning mechanism that enhances reliability in substation automation services. Finally, we couple the problem of state estimation in wide-area monitoring systems with the reliability challenges in information acquisition. Using our developed analytical framework, we quantify the impact of imperfect communication reliability in the state estimation accuracy and we provide useful insights for the design of reliability-aware state estimators.
The second part of the thesis builds on the previous one and focuses on the RAN problem of resource scheduling and sharing for smart grid and human-type traffic. We introduce a novel scheduler that achieves low latency for distribution automation traffic while resource allocation is performed in a way that keeps the degradation of cellular users at a minimum level. In addition, we investigate the benefits of Device-to-Device (D2D) transmission mode for event-based message exchange in substation automation scenarios. We design a joint mode selection and resource allocation mechanism which results in higher data rates with respect to the conventional transmission mode via the base station. An orthogonal resource partition scheme between cellular and D2D links is further proposed to prevent the underutilization of the scarce cellular spectrum.
The research findings of this thesis aim to deliver novel solutions to important RAN performance issues that arise when cellular networks support smart grid communication.Las redes celulares, p.e., los sistemas LTE/LTE-A, aparecen como una tecnología prometedora para facilitar la evolución de la próxima generación del sistema eléctrico de potencia, conocido como smart grid (SG). Sin embargo, la tecnología celular no fue pensada originalmente para las comunicaciones en la SG, asociadas con el intercambio fiable de mensajes y con requisitos de conectividad de un número masivo de dispositivos. Las diferencias fundamentales entre las comunicaciones en la SG y la comunicación de tipo humano desafían el diseño clásico de las redes celulares e introducen importantes cuestiones de investigación que hasta ahora no se han abordado suficientemente. Motivada por estos retos, esta tesis doctoral investiga los principios de diseño y analiza el rendimiento de una nueva red de acceso radio (RAN) que permita una integración perfecta del tráfico de la SG en las redes celulares futuras. Nos centramos en los problemas fundamentales de escalabilidad de la RAN en despliegues de SG masivos, y en la gestión de los recursos radio para la integración del tráfico de la SG con el tráfico de tipo humano. El objetivo principal de la tesis consiste en el diseño, el análisis y la evaluación del rendimiento de los mecanismos de las RAN que convertirán a las redes celulares en el elemento clave para las aplicaciones emergentes de las SGs. La primera parte de la tesis aborda las limitaciones del acceso radio en redes LTE para la comunicación fiable y escalable en SGs. En primer lugar, identificamos el problema de congestión en el acceso aleatorio de LTE que aparece en los despliegues de SGs a gran escala. Para superar este problema, se propone un nuevo mecanismo de acceso aleatorio que permite soportar de forma eficiente los servicios de automatización de la distribución eléctrica en tiempo real, con un impacto insignificante en el tráfico de fondo. Motivados por los estrictos requisitos de fiabilidad de las diversas operaciones en la SG, desarrollamos un modelo analítico del procedimiento de acceso aleatorio de LTE que nos permite evaluar el rendimiento del tráfico de monitorización de la red eléctrica basado en eventos bajo diversas condiciones de carga y configuraciones de red. Además, ampliamos nuestro análisis para incluir la relación entre el tamaño de celda y la disponibilidad de recursos de acceso aleatorio ortogonales, e identificamos un reto adicional para la conectividad fiable en la SG. Con este fin, diseñamos un mecanismo de planificación celular que tiene en cuenta las interferencias y la carga de la red, y que mejora la fiabilidad en los servicios de automatización de las subestaciones eléctricas. Finalmente, combinamos el problema de la estimación de estado en sistemas de monitorización de redes eléctricas de área amplia con los retos de fiabilidad en la adquisición de la información. Utilizando el modelo analítico desarrollado, cuantificamos el impacto de la baja fiabilidad en las comunicaciones sobre la precisión de la estimación de estado. La segunda parte de la tesis se centra en el problema de scheduling y compartición de recursos en la RAN para el tráfico de SG y el tráfico de tipo humano. Presentamos un nuevo scheduler que proporciona baja latencia para el tráfico de automatización de la distribución eléctrica, mientras que la asignación de recursos se realiza de un modo que mantiene la degradación de los usuarios celulares en un nivel mínimo. Además, investigamos los beneficios del modo de transmisión Device-to-Device (D2D) en el intercambio de mensajes basados en eventos en escenarios de automatización de subestaciones eléctricas. Diseñamos un mecanismo conjunto de asignación de recursos y selección de modo que da como resultado tasas de datos más elevadas con respecto al modo de transmisión convencional a través de la estación base. Finalmente, se propone un esquema de partición de recursos ortogonales entre enlaces celulares y D2
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Yi, Na. "Cooperative communication for future cellular networks." Thesis, University of Surrey, 2009. http://epubs.surrey.ac.uk/843080/.
Повний текст джерелаАнотація:
Cellular networks are multi-user communication systems that consist of three basic elements: interference, cooperation, and feedback. A fundamental goal of multi-user systems research is to find out the capacity limit and its achievability of a general model that consists of many senders, receivers, and intermediate nodes. In the past 60 years, a huge amount of research efforts have been paid towards five special problems of multi-user systems: multiple-access channel, broadcast channel, relay channel, crosstalk channel, and feedback channel. Although most of those problems have not received a satisfactory answer yet, rapid development of cellular networks have motivated communication-theoretic research about cooperation in those special channels. The primary objective of this thesis is to study the cooperation theory in relay and crosstalk channels. The overall organisation of this thesis is based on our new vision about cooperative behaviour in communication networks. This new vision indicates that cooperative behaviour in relay and crosstalk networks can be classified into three groups, namely. Postman, Host, and Synergy. The classification is based on how a cooperative node utilises the multi-user side information such as channel quality information (CQI), codebook, message, in various communication scenarios. Specifically, major contributions of this thesis are summarised as follows. The Postman describes cooperative behaviour in relay networks, where a cooperative node offers cooperation by delivering other's message to its desired destination. Our first work in this category is about doubly differential cooperative relaying scheme proposed for mobile communication over rapidly time-varying channel. It is shown that the proposed scheme can enjoy full cooperative diversity-gain without need of full channel state information. The other work in this category is about adaptive bit-power allocation for orthogonal frequency-division multiplexing (OFDM)-based relay networks. Provided full knowledge of CQI, a number of sub-optimum approaches have been proposed to improve the power efficiency through multi-link optimisation. The Host describes cooperative behaviour in cognitive interference networks, where a primary user offers cooperation to a secondary user by opening its own spectrum and sharing knowledge of side information. The work in this category is about overlay and underlay cognitive radio channels, where the primary user broadcasts its private codebook and knowledge of CQI, so that the secondary user can perceive the primary user's message and interference state. Capacity theorem of two-user Gaussian cognitive interference channels have been carefully investigated, based on which power allocation and spectrum access approaches have been proposed in terms of power and spectrum efficiency. The Synergy describes cooperative behaviour in crosstalk channels. A typical example is the cooperative bit-power allocation between two individual transmitter-receiver pairs. One cooperative behaviour is sharing of codebook and CQI between two transmitter-receiver pairs. The purpose of sharing is to maximize their common profit and to allow an optimal treatment of mutual interference. Provided full knowledge of multi-user CQI at transmitters, two transmitter-receiver pairs first perform iterative rate-adaptation to maximize the sum-rate, and then employ proportional fairness for rate allocation.
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Morshed, M. (Munim). "Wireless backhaul in future cellular communication." Master's thesis, University of Oulu, 2018. http://jultika.oulu.fi/Record/nbnfioulu-201809292841.
Повний текст джерелаАнотація:
Abstract. In 5G technology, huge number of connected devices are needed to be considered where the expected throughput is also very ambitious. Capacity is needed and thus used frequencies are expected to get higher (above 6 GHz even up to 80 GHz), the Cell size getting smaller and number of cells arising significantly. Therefore, it is expected that wireless backhaul will be one option for Network operators to deliver capacity and coverage for high subscriber density areas with reduced cost. Wireless backhaul optimization, performance and scalability will be on the critical path on such cellular system. This master’s thesis work includes connecting a base station by using the wireless backhaul by introducing a VPN in the proposed network. We find the bottleneck and its solution. The network is using 3.5 GHz wireless link instead of LAN wire for backhaul link between the EnodeB and the core network (OpenEPC). LTE TDD band 42 acting as a Wireless Backhaul (Link between EnodeB and Band 42 CPE Router). The status and attachment procedure are observed from different nodes of the openEPC and from the VPN machine. Step by step we have established a tunnel between the CPE device and the VPN server using PPTP and L2TP with IPSec tunneling protocol. The progression towards the final implementation brings in step by step all difficulties and bottlenecks are documented in the study.
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Kchao, Camroeum. "Direct sequence spread spectrum cellular radio." Diss., Georgia Institute of Technology, 1991. http://hdl.handle.net/1853/13719.
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Jiang, Hai. "Coverage vs. capacity analysis for CDMA cellular networks /." free to MU campus, to others for purchase, 2002. http://wwwlib.umi.com/cr/mo/fullcit?p3074412.
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Santini, Guillaume. "Conception fabrication et caractérisation d’un photorécepteur cohérent en filière PIC InP pour les applications 100-400 Gbit/s." Thesis, Evry, Institut national des télécommunications, 2017. http://www.theses.fr/2017TELE0024/document.
Повний текст джерелаАнотація:
Ce travail porte sur la conception, la fabrication et la caractérisation d’un photorécepteur cohérent en filière PIC InP pour les applications 100-400 Gbit/s. La solution retenue est un récepteur cohérent pré-amplifié par un SOA pour permettre d’améliorer la responsivité du récepteur par rapport à un récepteur cohérent classique. De plus, ce récepteur est réalisé en technologie enterrée pour permettre un fonctionnement sur une plus grande gamme de longueurs d’onde. Enfin, un récepteur cohérent non pré-amplifié est aussi réalisé pour pouvoir évaluer l’impact de l’intégration du SOA sur le fonctionnement de notre récepteur. La première partie de cette étude est consacrée à des rappels sur les transmissions optiques à très haut débit, à un état de l’art sur les récepteurs cohérents, à une présentation des différents photodétecteurs et à une présentation de l’hybrid 90° qui est le composant coeur des récepteurs cohérents. Dans un second temps, nous présentons les différents choix retenus pour la conception de notre récepteur. L’étude de deux hybrid 90° simulés en technologie ridge et en technologie enterrée est détaillée. Nous commentons également le choix des photodiodes ainsi que le choix du SOA utilisé pour notre composant. Le troisième chapitre est consacré aux différentes étapes technologiques permettant la fabrication de notre récepteur cohérent pré amplifié. Nous commençons par une description des différentes techniques d’épitaxie utilisées. Ensuite, nous présentons en détails les 22 étapes technologiques nécessaires pour réaliser notre récepteur. Enfin, nous regroupons l’ensemble des caractérisations réalisées sur notre récepteur cohérent. Après un rappel sur les différentes parties de celui-ci et de leurs performances clés, nous caractérisons les composants unitaires formant notre récepteur (mixeur cohérent, photodiodes UTC et SOA). Enfin nous présentons les caractéristiques statiques et dynamiques de notre récepteur et nous comparons ses performances avec celles de l’état de l’art. Ces travaux de thèse ont permis de démontrer la faisabilité d’un récepteur pré-amplifié utilisant un SOA intégré en technologie InP enterrée avec un record de responsivité de 5 A/W. Ceci représente un gain de 12,5 dB par rapport à un récepteur cohérent non amplifié idéal et un gain de 15,5 dB par rapport à l’état de l’art des récepteurs cohérents. De plus, la consommation engendrée par cette intégration reste très faible (240 mW). Enfin, nous avons démontré une démodulation à 32 Gbauds avec un facteur Q de 14 dB. La bande passante de 40 GHz de nos diodes est compatible avec des applications à 56 Gbauds et peut être améliorée pour des applications à 100 Gbauds en réduisant la taille des photodiodes. Ce travail de thèse ouvre donc le chemin pour de nouveaux récepteurs pré-amplifés par un SOA pour des applications à 400 Gbit/sThis work focuses on the design, manufacturing and characterization of a coherent photoreceptor in PiC InP for 100-400 Gbit/s applications. The chosen solution is a preamplified coherent receiver with an SOA to improve the responsivity compared to a conventional coherent receiver. In addition, this receiver is made in buried technology to allow operation over a wider range of wavelengths. Finally, a coherent receiver without SOA is also produced to be able to evaluate its impact on the performances of our receiver. The first part of this study is devoted to reminders about very high speed optical transmissions, about state of the art on coherent receivers, about a presentation of the different photodetectors and a presentation of the 90° hybrid which is the core component in coherent receivers. Secondly, we present the various choices made for the design of our receiver. The study of two 90° hybrids simulated in ridge or in buried technology is detailed. We also comment the choices of photodiodes and SOA used for our component. The third chapter is devoted to the different technological steps used to build our preamplified receiver. We start with a description of the different epitaxial techniques used. Then, we present in detail the 22 technological steps required to realize our receiver. Finally, we group all the characterizations preformed on our coherent receiver. We characterize the unitary components of our receiver (hybrid 90°, UTC photodiodes and SOA). Finally we present the static and dynamic characteristics of our receiver and we compare its performances with the state of the art. This thesis demonstrates the feasibility of a preamplified receiver using a SOA in buried InP technology with a record of reponsivity of 5 A/W. This represents a gain of 12.5 dB compared to an ideal coherent receiver and a gain of 15,5 dB compared to the state of the art. In addition, the consumption generated by this integration remains very low (240 mW). Finally, we have demonstrated a 32 Gbauds demodulation with a Q factor of 14dB and the 40 GHz bandwidth of our photodiodes is compatible with 56 Gbauds applications. It can be improved for 100 Gbauds applications by reducing the size of our photodiodes. This thesis opens the way for a new preamplified coherent receiver for 400 Gbit/s applications
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Lorrière, Nominoë. "Cellules photovoltaïques pour la récupération d'énergie et la communication de données." Electronic Thesis or Diss., Aix-Marseille, 2019. http://www.theses.fr/2019AIXM0570.
Повний текст джерелаАнотація:
L’invention des LED bleues de forte intensité en 1993 a permis une révolution générale de l’éclairage pour le grand public aussi bien que pour les commerces. Ces nouveaux dispositifs, proposent un rendement énergétique bien supérieur aux technologies commerciales précédentes, ce qui explique leur déploiement massif depuis la fin des années 2000. Les matériaux semiconducteurs composant les LED sont déjà utilisés dans le domaine de la microélectronique pour effectuer des fonctions logiques à hautes fréquences.La technologie LiFi tend à cumuler ces deux propriétés en ajoutant une fonction de transmission d’information aux points d’éclairages existants. L’information est transmise en modulant l’intensité de la lumière à haute fréquence, bien au delà des capacités distinctives de l’oeil. Cette technologie devrait subir un déploiement avec l’arrivée de l’Internet des Objets (IoT) qui apporte une grande demande de connections sans fil, incompatible avec les réseaux radiofréquences actuels. Le travail présenté ici porte sur la réception de cette modulation lumineuse. Les récepteurs usuellement utilisés sont des photodiodes mais ces dernières imposent des contraintes d’éclairage et de consommation difficilement corrélables avec les impératifs de l’IoT. Ainsi, ces travaux étudient la possibilité de réception de la modulation LiFi par des cellules et modules photovoltaïques, dont les deux principales qualités restent les grandes dimensions du détecteur permettant une omnidirectionnalité de réception et une résistance à l’ombrage ainsi que le caractère passif de la détectionThe invention of high-intensity blue LED hit the market and the retail industry in 1993. It even brought a revolution in lighting history. These new devices significantly improved energy efficiency than ever before and led to their massive deployment since the end of the 2000s. Semiconductor materials for LED devices are used in the microelectronics domain to implement high-frequency logic functions.Light fidelity (LiFi) technologies combine illumination and communication capabilities by implanting information transmission function to existing lighting equipment. Information is transmitted by using intensity modulation of optical sources at high frequencies, far beyond the range of visual perception. LiFi is an enabling technology for the Internet of Things (IoT) systems. IoT requires a large number of wireless connections, so it is not compatible with existing radiofrequency networks.This work is based on the reception of light modulation. Photodiodes are the mostly used receivers, however their constraints on lighting and consumption make it difficult to meet the requirements of the IoT. On the ground of this, this research is aimed at studying the possibility of receiving LiFi modulation by photovoltaic cells and modules due to their two main qualities: passive detection and large dimensions (omnidirectional reception and shade resistance)
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Shiu, Wan Yi. "Noniterative digital beamforming in CDMA cellular communications systems." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ36081.pdf.
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Najari, Moghadam Nima. "On Multiantenna Cellular Communications: From Theory to Practice." Doctoral thesis, KTH, Teknisk informationsvetenskap, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-207623.
Повний текст джерелаАнотація:
Today, wireless communications are an essential part of our everyday life. Both the number of users and their demands for wireless data have increasedtremendously during the last decade. Multiantenna communicationsis a promising solution to meet this ever-growing traffic demands. However, impairments that exist in most practical communication networks may substantially limit the performance of a multiantenna system. The characterizationof such a performance loss and how to minimize that are still largelyopen problems. The present thesis addresses this important research gap. Inparticular, we focus on three major impairments of a multiantenna cellularnetwork: impairment in the channel state information (CSI), interference andimpairment in the transceiver hardware components.To fully realize the benefits of multiantenna communications, the users need to acquire a certain level of information about their propagation environment; that is, their corresponding CSI. In practice, the CSI is not known bythe users and should be acquired by allocating part of the network resourcesfor pilot transmission. This problem is mainly important in the systems with a large number of antennas, as in general the required network resources for CSI acquisition scales with the number of transmitting antennas. Theproblem of CSI acquisition in a single-cell multiuser multiple-input multipleoutput(MIMO) system is addressed in this thesis. A linear spatial precodingand combining scheme for pilot transmission is proposed. This scheme requiresless number of network resources for channel estimation compared tothe conventional schemes. The gains of the proposed scheme are characterized by finding an upper-bound and a lower-bound on the channel estimation error.Moreover, as an ultimate performance metric, an achievable sum-rate ofthe network is formulated and analyzed numerically.Due to the broadcast nature of the wireless channels, the performanceof the users in a network is intertwined; the desired signal of one user mayinterfere other users. Hence, the interference is another major impairment inwireless communication systems. In this thesis, the practical challenges of aninterference management technique, namely MIMO interference alignment isinvestigated by implementation on a multiuser MIMO testbed. Then, in thecontext of interference alignment, the problem of optimal power allocation forpilot and data transmission is studied and verified by the measurements.The impairment in the hardware components of the transceivers, that is, any deviation of the components from their ideal behavior, degrades the performance of a communication system. In particular, the impact of nonlineartransmitter power amplifiers (PA)s is investigated in this thesis. First, consideringa memoryless third-order polynomial model for the PAs, a model forthe transmitted nonlinear distortion signal from a multiantenna transmitter isproposed and validated by measurements. This model implies that the spatialdirection of the transmitted distortion is dependent on the spatial directionof the desired signal. Then, this model is extended for a general arbitrary order polynomial model. Exploiting the developed distortion model, the energyefficiency of a multiantenna system operating at millimeter wave frequenciesis studied.QC 20170523
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Wu, Cynara C. "Dynamic resource allocation in CDMA cellular communications systems." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/9332.
Повний текст джерелаАнотація:
Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1999.Includes bibliographical references (p. 115-117).
Efficient resource utilization is the primary problem in cellular communication systems. In this thesis, we combine the main resource issues for CDMA systems, admission control and power control, in a single framework. The framework uses a formulation that is general enough to incorporate all significant parameters of a system, yet tractable to compute. We formulate the resource allocation problem as a Markov decision process. Due to the enormous size of the state space, applying the traditional solution technique, dynamic programming, is impractical. We therefore consider approximation techniques. As a first step towards simplification, we divide the problem into two subproblems: optimal admission control with heuristic power control and optimal power control with heuristic admission control. We formulate the problem of optimal admission control as a Markov decision process and consider several approximate dynamic programming techniques. We apply these techniques to a simulated system and obtain results that improve significantly upon two commonly used policies, the greedy policy and the reservation policy. We then consider the minimization of the total power transmitted over given discrete sets of available power levels subject to maintaining an acceptable signal quality for each mobile. We develop sequential and distributed iterative algorithms for solving a more general version of this integer programming problem and show that they find the optimal solution in a finite number of iterations which is polynomial in the number of power levels and the number of mobiles.
by Cynara C. Wu.
Ph.D.
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Guha, Sayantan. "Cellular-Assisted Vehicular Communications: A Stochastic Geometric Approach." Thesis, Virginia Tech, 2016. http://hdl.handle.net/10919/78467.
Повний текст джерелаАнотація:
A major component of future communication systems is vehicle-to-vehicle (V2V) communications, in which vehicles along roadways transfer information directly among themselves and with roadside infrastructure. Despite its numerous potential advantages, V2V communication suffers from one inherent shortcoming: the stochastic and time-varying nature of the node distributions in a vehicular ad hoc network (VANET) often leads to loss of connectivity and lower coverage. One possible way to improve this coverage is to allow the vehicular nodes to connect to the more reliable cellular network, especially in cases of loss of connectivity in the vehicular network. In this thesis, we analyze this possibility of boosting performance of VANETs, especially their node coverage, by taking assistance from the cellular network.
The spatial locations of the vehicular nodes in a VANET exhibit a unique characteristic: they always lie on roadways, which are predominantly linear but are irregularly placed on a two dimensional plane. While there has been a signifcant work on modeling wireless networks using random spatial models, most of it uses homogeneous planar Poisson Point Process (PPP) to maintain tractability, which is clearly not applicable to VANETs. Therefore, to accurately capture the spatial distribution of vehicles in a VANET, we model the roads using the so called Poisson Line Process and then place vehicles randomly on each road according to a one-dimensional homogeneous PPP. As is usually the case, the locations of the cellular base stations are modeled by a planar two-dimensional PPP. Therefore, in this thesis, we propose a new two-tier model for cellular-assisted VANETs, where the cellular base stations form a planar PPP and the vehicular nodes form a one-dimensional PPP on roads modeled as undirected lines according to a Poisson Line Process.
The key contribution of this thesis is the stochastic geometric analysis of a maximum power-based cellular-assisted VANET scheme, in which a vehicle receives information from either the nearest vehicle or the nearest cellular base station, based on the received power. We have characterized the network interference and obtained expressions for coverage probability in this cellular-assisted VANET, and successfully demonstrated that using this switching technique can provide a significant improvement in coverage and thus provide better vehicular network performance in the future. In addition, this thesis also analyzes two threshold-distance based schemes which trade off network coverage for a reduction in additional cellular network load; notably, these schemes also outperform traditional vehicular networks that do not use any cellular assistance. Thus, this thesis mathematically validates the possibility of improving VANET performance using cellular networks.Master of Science
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Cardieri, Paulo. "Resource Allocation and Adaptive Antennas in Cellular Communications." Diss., Virginia Tech, 2000. http://hdl.handle.net/10919/29051.
Повний текст джерелаАнотація:
The rapid growth in demand for cellular mobile communications and emerging fixed wireless access has created the need to increase system capacity through more efficient utilization of the frequency spectrum, and the need for better grade of service. In cellular systems, capacity improvement can be achieved by reducing co-channel interference.
Several techniques have been proposed in literature for mitigating co-channel interference, such as adaptive antennas and power control. Also, by allocating transmitter power and communication channels efficiently (resource allocation), overall co-channel interference can be maintained below a desired maximum tolerable level, while maximizing the carried traffic of the system.
This dissertation presents investigation results on the performance of base station adaptive antennas, power control and channel allocation, as techniques for capacity improvement. Several approaches are analyzed. Firstly, we study the combined use of adaptive antennas and fractional loading factor, in order to estimate the potential capacity improvement achieved by adaptive antennas.
Next, an extensive simulation analysis of a cellular network is carried out aiming to investigate the complex interrelationship between power control, channel allocation and adaptive antennas. In the first part of this simulation analysis, the combined use of adaptive antennas, power control and reduced cluster size is analyzed in a cellular system using fixed channel allocation.
In the second part, we analyze the benefits of combining adaptive antennas, dynamic channel allocation and power control. Two representative channel allocation algorithms are considered and analyzed regarding how efficiently they transform reduced co-channel interference into higher carried traffic. Finally, the spatial filtering capability of adaptive antennas is used to allow several users to share the same channel within the same cell. Several allocation algorithms combined with power control are analyzed.Ph. D.
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Cruz, Bruno de Oliveira. "Impact of M2M communications on cellular telecommunications networks." Master's thesis, Universidade de Aveiro, 2013. http://hdl.handle.net/10773/14475.
Повний текст джерелаАнотація:
Mestrado em Engenharia Electrónica e de TelecomunicaçõesAs comunicações Máquina-Máquina (M2M) apresentam um crescimento muito significativo e algumas projeções apontam para que esta tendência se acentue drasticamente ao longo dos próximos anos. O tráfego gerado por este tipo de comunicações tem caraterísticas muito diferentes do tráfego de dados, ou voz, que atualmente circula nas redes celulares de telecomunicações. Assim, é fundamental estudar as caraterísticas dos tipos de tráfego associados com comunicações M2M, por forma a compreender os efeitos que tais caraterísticas podem provocar nas redes celulares de telecomunicações. Esta dissertação procura identificar e estudar algumas das caraterísticas do tráfego M2M, com especial enfoque na sinalização gerada por serviços M2M. Como resultado principal deste trabalho surge o desenvolvimento de modelos que permitem a construção de uma ferramenta analítica de orquestração de serviços e análise de rede. Esta ferramenta permite orquestrar serviços e modelar padrões de tráfego numa rede UMTS, possibilitando uma análise simultânea aos efeitos produzidos no segmento core da mesma rede. Ao longo deste trabalho procura-se que a abordagem aos problemas apresentados permita que os resultados obtidos sejam válidos, ou adaptáveis, num âmbito mais abrangente do que apenas as comunicações M2M.
Machine to Machine (M2M) communications present significant growth and some projections indicate that this trend is going to increase dramatically over the coming years. The traffic generated by this type of communication has very different characteristics when compared to data or voice traffic currently going through cellular telecommunications networks. Thus, it is essential to study the characteristics of traffic associated with M2M communications in order to understand the effects that its features can imply to cellular telecommunications networks. This dissertation tries to identify and study some of the characteristics of M2M traffic, with particular focus on signaling generated by M2M services. A number of models, that enable the development of an analytic tool for service orchestration and network analysis, are presented. This tool enables service orchestration and traffic modeling on a UMTS network, with simultaneous visualization of the impacts on the core of such network. The work presented in this document seeks to approach the problems at study in ways ensuring that its outcomes are valid for a wider scope than just M2M communications.
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Chong, Peter H. J. "Channel assignment schemes in cellular communication systems." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0018/NQ56660.pdf.
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Ali, Ahmed H. "Advanced handover procedure for cellular communication systems." Thesis, Aston University, 1998. http://publications.aston.ac.uk/7974/.
Повний текст джерелаАнотація:
Third Generation cellular communication systems are expected to support mixed cell architecture in which picocells, microcells and macrocells are used to achieve full coverage and increase the spectral capacity. Supporting higher numbers of mobile terminals and the use of smaller cells will result in an increase in the number of handovers, and consequently an increase in the time delays required to perform these handovers. Higher time delays will generate call interruptions and forced terminations, particularly for time sensitive applications like real-time multimedia and data services. Currently in the Global System for Mobile communications (GSM), the handover procedure is initiated and performed by the fixed part of the Public Land Mobile Network (PLMN). The mobile terminal is only capable of detecting candidate base stations suitable for the handover; it is the role of the network to interrogate a candidate base station for a free channel. Handover signalling is exchanged via the fixed network and the time delay required to perform the handover is greatly affected by the levels of teletraffic handled by the network. In this thesis, a new handover strategy is developed to reduce the total time delay for handovers in a microcellular system. The handover signalling is diverted from the fixed network to the air interface to prevent extra delays due to teletraffic congestion, and to allow the mobile terminal to exchange signalling directly with the candidate base station. The new strategy utilises Packet Reservation Multiple Access (PRMA) technique as a mechanism to transfer the control of the handover procedure from the fixed network to the mobile terminal. Simulation results are presented to show a dramatic reduction in the handover delay as compared to those obtained using fixed channel allocation and dynamic channel allocation schemes.
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MONTEIRO, MARC OLIVERO REGO. "DYNAMIC PRICING IN CELLULAR MOBILE COMMUNICATION NETWORKS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2001. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=2159@1.
Повний текст джерелаАнотація:
CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOEste trabalho apresenta um modelo de tarifação dinâmica cujo objetivo é determinar qual o preço que deve ser cobrado por uma chamada telefônica, originada em uma estação móvel, de forma a maximizar a receita da empresa operadora do serviço móvel celular, garantindo os valores máximos aceitáveis para a probabilidade de bloqueio de uma chamada e para a probabilidade de queda de ligações devido ao handoff.
This work presents a dynamic pricing model whose objective is to determinate the price that should be charged for a telephone call originated in a mobile phone in order to maximize the telephone enterprise revenue as long as it guarantees the maximum acceptable values for the probability of blocking of originating calls and for calls that are requesting a handoff.
Este trabajo presenta un modelo de tarifación dinámica cuyo objetivo es determinar cuál es el precio que deve ser cobrado por una llamada telefónica, originada en una estación móvil, de tal forma que maximize la receta de la empresa operadora del servicio móvil celular, garantizando los valores máximos aceptables para la probabilidad de bloqueo de una llamada y para la probabilidad de caída de conexión debido al handoff.
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GONDIM, PAULO ROBERTO DE LIRA. "MOBILITY MANAGEMENT IN MOBILE CELLULAR COMMUNICATION NETWORS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 1998. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=8478@1.
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COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIORNos últimos anos, considerável debate tem ocorrido a respeito do tema gerência de mobilidade, face à necessidade de se fazer uso judicioso dos recursos de sinalização destinados para esse fim no âmbito de sistemas de comunicação móvel celular e de sistemas de comunicação pessoal (PCS). Dentre as estratégias de gerência de mobilidade, destaca-se a utilização do conceito de áreas de registro, amplamente empregadas a partir dos sistemas de 2a. geração, e permitindo reduzir o consumo de recursos devido a atualizações de localização. Outro conceito, o de áreas de paging, tem também se tornado bastante difundido, propiciando a economia de recursos gastos na procura de terminais móveis por ocasião de tentativas de completamento de chamadas para estes terminais. Este trabalho inicia-se com discussão a respeito de modelos de mobilidade empregados no estudo de problemas e técnicas da área de comunicações móveis. Dentre tais modelos, destacam- se no contexto do trabalho o modelo baseado em fluxo de fluídos e o modelo gravitacional. O problema de particionamento em áreas de localização (LAPP) é então tratado como um problema de particionamento de grafos, cuja elevada complexidade enseja a utilização de heurísticas capazes de propiciar a obtenção de soluções próximas da ótima. As heurísticas propostas destinam-se ao caso mais comum, em que áreas de localização são coincidentes com áreas de paging. Com base em metodologia utilizada para o LAPP, são propostas soluções para um outro problema, o ISHMP (Inter-Switch Handover Minimization Problem), cuja importância se prende não só ao elevado consumo de recursos mas também aos atrasos impostos pelo sistema aos usuários quando estes trocam de área de Mobile Switching Center. Assim, reduzir ao máximo a ocorrência de tais eventos é vantajoso tanto do ponto de vista do usuário quanto do sistema. As heurísticas propostas são essencialmente as mesmas para ambos os problemas, e mostram superioridade em termos de qualidade das soluções obtidas quando comparadas com propostas de outros autores, através de casos-padrão publicados na literatura e de testbed construído especialmente para a comparação. Apresenta-se ainda discussão a respeito de modelos de mobilidade empregados no estudo de problemas e técnicas da área de comunicações móveis. Dentre tais modelos, destacam- se o modelo baseado em fluxo de fluidos e o modelo gravitacional. O trabalho apresenta também estudo relativo às cargas de sinalização que ocorrem tnato na rede fixa (incluindo o tráfego de consultas e atualizações sobre as bases de dados) quanto na interface aérea. No apêndice, considerando o grafo que modela a rede celular, apresenta-se comprovação formal da conversão de pesos de nós e de arestas em novos pesos de arestas, permitindo o tratamento dos dois problemas de particionamento aqui abordados como problemas de edgepartitioning puros.
In the past few years there hás been considerable debate over the question of mobility management in móbile cellular communication networks, due to the need of using the signaling system resources in a careful way. Among the strategies of location management, the utilization of registration areas has been difunded since the emergence of the second generation mobile communication systems, allowing to reduce the resource consumption due to location updates. Another concept, named paging areas, has also been extensively employed, allowing to save resources utilized localization of mobile terminals during the call setup for mobile stations. Initially, the Location Area Partitioning Problem (LAPP) is treated as a graph partitioning problem, largely recognized as NP-complete ([GARE 79], [LENG 90]) and leading to the utilization of heuristics, able to produce good sub-optimal solutions. The heuristics are proposed to solve the more usual case, where location areas are coincident with paging areas, and the frequency spectrum (radio resources). With the same methodology, another problem, named Inter- Switch Handover Minimization Problem (ISHMP), is adequately solved, being its relevance due to the elevated system resource consumption and to the severe delays imposed to users when their Mobile Switching Centers are changed. Thus, the diminution of the occurrence of such events id advantageous from both the user`s and the system`s points of view. The heuristics are eddentially the same for the two problems, and it is shown the superiority of the quality of the quality of the obtained solutions, when comparing them with other published results. The work also presents discussion about mobility models employed in the study of problems and techniques in the mobile communications area. Among such models, the fluid flow and the gravitational models are highlighted. A study concerning to the signaling load imposed to the fixed network (including queries and location update traffic over databases) and to the air interface is presented. Finally, starting from the average rate of mobile terminated calls and from a previously defined user impatience threshold, a new proposal for the definition of the optimal number of cells per paging area is presented.
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Peteinatos, Ilias. "WCDMA for aeronautical communications." Thesis, Brunel University, 2014. http://bura.brunel.ac.uk/handle/2438/11502.
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In this thesis, a study of the capacity of a suggested three - dimensional Air-to-Ground cellular system is being made. The Outside Cell Interference Factor (OCIF) is being calculated through simulations for reverse and forward link using seven loops, from the interfering cells around the desired cell for different values of the maximum height of the cell and its radius. Capacity per cell as well as delay and throughput for packet data transmission was calculated for the first time through closed form equations, with the use of the load factor, the activity factor and sectoring gain using the Automatic Repeat Request (ARQ) algorithm for the correction of errors. Moreover, in this thesis, the algorithm which has been created is being analyzed and used for the simulations. Moreover, for the first time, a case study has been made involving the study of capacity of the Air – to - Ground system for the airports of Greece, in three basic scenarios in which the number of the users, the delay and the throughput per cell is being calculated. In the first scenario, we are restricting to the three major airports of the country, while in the second it expands to six airports covering from the radio-coverage side almost all Greece. In the first two scenarios the same cell radius of 175 km is being used, while in the third the radius is reduced to 100 km and the airports are increased to nineteen. In all three scenarios we assume that all the users use the same service. The voice services are also studied of 12.2 kbps and data with transmission rate 64, 128 and 384 kbps. From scenarios 1 and 2 (cell radius 175 km), it was found that we can service at the same time up to 179 voice subscribers per cell at bit rate 12.2 kbps which reduces to 33 users for video call of 64 kbps and in 18 for video call of 128 kbps. In scenario 3 (cell radius 100km),it was found that we can serve at the same time until 126 voice subscribers per cell at bit rate 12.2 kbps which reduces to 23 users for video call of the 64 kbps and in 13 for video call of 128 kbps. In scenario 3 although the capacity per cell is lower than in scenarios 1 and 2, it provides greater total capacity (for all Greece) in relation to these scenarios.
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Wu, Jianjun. "Adaptive equalisation techniques for future mobile communications." Thesis, King's College London (University of London), 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.338815.
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Todd, Stephen Ross Carleton University Dissertation Engineering Electrical. "Empirical evaluation of diversity techniques for indoor digital radio at 1.75 GHz." Ottawa, 1992.
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Phongphanphanee, Chai. "Multilayer mobile communication systems." Thesis, University of Southampton, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.324001.
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Björnson, Emil. "Multiantenna Cellular Communications : Channel Estimation, Feedback, and Resource Allocation." Doctoral thesis, KTH, Signalbehandling, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-45035.
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The use of multiple antennas at base stations and user devices is a key component in the design of cellular communication systems that can meet the capacity demands of tomorrow. The downlink transmission from base stations to users is particularly limiting, both from a theoretical and a practical perspective, since user devices should be simple and power-efficient, and because many applications primarily create downlink traffic (e.g., video streaming). The potential gain of employing multiple antennas for downlink transmission is well recognized: the total data throughput increases linearly with the number of transmit antennas if the spatial dimension is exploited for simultaneous transmission to multiple users. In the design of practical cellular systems, the actual benefit of multiuser multiantenna transmission is limited by a variety of factors, including acquisition and accuracy of channel information, transmit power, channel conditions, cell density, user mobility, computational complexity, and the level of cooperation between base stations in the transmission design. The thesis considers three main components of downlink communications: 1) estimation of current channel conditions using training signaling; 2) efficient feedback of channel estimates; and 3) allocation of transmit resources (e.g., power, time and spatial dimensions) to users. In each area, the thesis seeks to provide a greater understanding of the interplay between different system properties. This is achieved by generalizing the underlying assumptions in prior work and providing both extensions of previous outcomes and entirely new mathematical results, along with supporting numerical examples. Some of the main thesis contributions can be summarized as follows. A framework is proposed for estimation of different channel quantities using a common optimized training sequence. Furthermore, it is proved that each user should only be allocated one data stream and utilize its antennas for receive combining and interference rejection, instead of using the antennas for reception of multiple data streams. This fundamental result is proved under both exact channel acquisition and under imperfections from channel estimation and limited feedback. This also has positive implications on the hardware and system design. Next, a general mathematical model is proposed for joint analysis of cellular systems with different levels of base station cooperation. The optimal multicell resource allocation can in general only be found with exponential computational complexity, but a systematic algorithm is proposed to find the optimal solution for the purpose of offline benchmarking. A parametrization of the optimal solution is also derived, creating a foundation for heuristic low-complexity algorithms that can provide close-to-optimal performance. This is exemplified by proposing centralized and distributed multicell transmission strategies and by evaluating these using multicell channel measurements.In reference to IEEE copyrighted material which is used with permission in this thesis, the IEEE does not endorse any of KTH Royal Institute of Technology's products or services. Internal or personal use of this material is permitted. If interested in reprinting/republishing IEEE copyrighted material for advertising or promotional purposes or for creating new collective works for resale or redistribution, please go to http://www.ieee.org/publications_standards/publications/rights/rights_link.html to learn how to obtain a License from RightsLink.QC 20111026
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Wang, Li-Chun. "Channel modeling and architecture for cellular-based personal communications." Diss., Georgia Institute of Technology, 1996. http://hdl.handle.net/1853/13716.
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Verenzuela, Daniel. "Scalability of Device-to-Device Communications in Cellular Networks." Thesis, KTH, Skolan för informations- och kommunikationsteknik (ICT), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-187444.
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In current cellular networks the demand of traffic is rapidly increasing and new techniques need to be developed to accommodate future service requirements. Device-to-Device (D2D) communications is one technique that has been proposed to improve the performance of the system by allowing devices to communicate directly without routing traffic through the base station. This technique has the means to improved performance and support new proximity based services. Nowadays new applications based on geographical proximity are becoming more and more popular suggesting that D2D communications will have a high de- mand in the near future. Thus the study of the scalability of D2D communications is of paramount importance. We define the scalability of D2D communications underlay cellular networks as the maximum number of D2D links that can share the cellular resources while assuring QoS to both D2D links and cellular users. In this thesis we study the scalability of D2D communication underlay cellu- lar networks in a multi-cell environment. We propose interference coordination schemes to maximize the number of D2D links while assuring QoS to D2D links and cellular users. Three interference coordination schemes have been proposed considering dif- ferent levels of available channel state information (CSI). The first scheme is called no CSI centralized (N-CSIC) scheme and it is based on a centralized solution where no CSI is needed. The second is partial CSI distributed (P-CSID) scheme and it is based on a distributed solution where partial CSI is available. The last scheme is named full CSI optimal (F-CSIOp) scheme and it is achieved by formulating an optimization problem considering full CSI to be available. Extensive mathematical and numerical analysis is conducted to develop and evaluate the proposed schemes. The results show that F-CSIOp scheme offers the best performance followed by the P-CSID and finally N-CSIC, thus a clear relationship is found between complexity and performance. The P-CSID offers a practical solution for a low complexity interference co- ordination scheme that achieves good scalability and capacity for a wide range of strict QoS requirements. Moreover the results show that further improvement can be achieved if proper selection of the involved parameters is done along with the implementations of closed loop power control (CLPC) schemes. The N-CSIC scheme provides a good solution for low SINR values of D2D links when the QoS of cellular users is low. Thus it is a good candidate for applications like sensor networks or M2M communications where the SINR requirements are rather low and there are no primary users to impose more interference constraints. Finally we conclude that good scalability and capacity can be achieved with the proposed low complexity interference coordination schemes for D2D communications and provide interesting topics for future research.