Thesis (M.A.)--University of Massachusetts Amherst, 2009. / Open access. Includes bibliographical references (p. 144-154).

Power conservation has become a severe issue in devices since battery capability advancement is not keeping pace with the swift development of other technologies such as processing technologies. This issue becomes critical when both the number of resource-intensive applications and the number of connected devices are rapidly growing. The former results in an increase in power consumption per device, and the latter causes an increase in the total power consumption of devices. Mobile edge computing (MEC) and low power wide area networks (LPWANs) are raised as two important research areas in wireless networks, which can assist devices to save power. On the one hand, devices are being considered as a platform to run resource-intensive applications while they have limited resources such as battery and processing capabilities. On the other hand, LPWANs raised as an important enabler for massive IoT (Internet of Things) to provide long-range and reliable connectivity for low power devices. The scope of this thesis spans over these two main research areas: (1) MEC, where devices can use radio resources to offload their processing tasks to the cloud to save energy. (2) LPWAN, with grant-free radio access where devices from different technology transmit their packets without any handshaking process. In particular, we consider a MEC network, where the processing resources are distributed in the proximity of the users. Hence, devices can save energy by transmitting the data to be processed to the edge cloud provided that the delay requirement is met and transmission power consumption is less than the local processing power consumption. This thesis addresses the question of whether to offload or not to minimize the uplink power consumption in a multi-cell multi-user MEC network. We consider the maximum acceptable delay as the QoS metric to be satisfied in our system. We formulate the problem as a mixed-integer nonlinear problem, which is converted into a convex form using D.C. approximation. To solve the converted optimization problem, we have proposed centralized and distributed algorithms for joint power allocation and channel assignment together with decision-making on job offloading. Our results show that there exists a region in which offloading can save power at mobile devices and increases the battery lifetime. Another focus of this thesis is on LPWANs, which are becoming more and more popular, due to the limited battery capacity and the ever-increasing need for durable battery lifetime for IoT networks. Most studies evaluate the system performance assuming single radio access technology deployment. In this thesis, we study the impact of coexisting competing radio access technologies on the system performance. We consider K technologies, defined by time and frequency activity factors, bandwidth, and power, which share a set of radio resources. Leveraging tools from stochastic geometry, we derive closed-form expressions for the successful transmission probability, expected battery lifetime, experienced delay, and expected number of retransmissions. Our analytical model, which is validated by simulation results, provides a tool to evaluate the coexistence scenarios and analyze how the introduction of a new coexisting technology may degrade the system performance in terms of success probability, delay, and battery lifetime. We further investigate the interplay between traffic load, the density of access points, and reliability/delay of communications, and examine the bounds beyond which, mean delay becomes infinite. / Antalet anslutna enheter till nätverk ökar. Det finns olika trender som mobil edgecomputing (MEC) och low power wide area-nätverk (LPWAN) som har blivit intressantai trådlösa nätverk. Därför står trådlösa nätverk inför nya utmaningar som ökadenergiförbrukning. I den här avhandlingen beaktar vi dessa två mobila nätverk. I MECavlastar mobila enheter sina bearbetningsuppgifter till centraliserad beräkningsresurser (”molnet”). I avhandlingensvarar vi på följande fråga: När det är energieffektivt att avlasta dessa beräkningsuppgifter till molnet?Vi föreslår två algoritmer för att bestämma den rätta tiden för överflyttning av beräkningsuppgifter till molnet.I LPWANs, antar vi att det finns ett mycket stort antal enheter av olika art som kommunicerar mednätverket. De använder s.k. ”Grant-free”-åtkomst för att ansluta till nätverket, där basstationerna inte ger explicita sändningstillstånd till enheterna. Denanalytiska modell som föreslås i avhandlingen utgör ett verktyg för att utvärdera sådana samexistensscenarier.Med verktygen kan vi analysera olika systems prestanda när det gäller framgångssannolikhet, fördröjning och batteriershållbarhetstid. / <p>QC 20200228</p> / SOOGreen

Dans cette thèse, nous nous demandons comment les mouvements contreculturels ont trouvé de nouveaux lieux d’expression grâce à la plus grande accessibilité de l’audiovisuel, grâce aussi au combat des « radios libres ». Plus précisément, nous cherchons à savoir pourquoi et comment la société et l’audiovisuel français ont permis la constitution d’un média alternatif radiophonique comme Radio Ici et Maintenant (RIM) et comment cette radio a trouvé un modèle économique viable pour diffuser son idéologie. Nous verrons que l’existence et la persistance de RIM est due à la conjonction de deux phénomènes : d’une part la diminution du coût d’entrée dans la radiophonie grâce au développement et au combat des « radios libres » qui ont donné naissance aux radios associatives (avec leur modèle juridico-économique spécifique), et d’autre part la diminution du coût d’entrée dans le marché religieux avec le développement de la contreculture New Age française issue de la contreculture américaine, elle-même issue des pensées religieuses alternatives occidentales (liées à l’ésotérisme, au médiumnisme) et des religions orientales (l’hindouisme et le bouddhisme). Ainsi, le modèle juridico-économique spécifique des radios associatives a permis de faire vivre puis persister l’idéologie « radiolibriste » et New Age au sein de RIM. Mais ajoutons que ce modèle n’aurait pas été possible s’il n’avait pas été porté par des animateurs bénévoles, des invités militants et des auditeurs actifs dont nous analysons ici le profil sociologique. L’intérêt scientifique de ce sujet provient du fait qu’il s’agit principalement d’étudier RIM qui est une ancienne « radio libre ». Elle a été l’une des radios les plus importantes au sein du mouvement. C’est la plus ancienne des radios locales privées parisiennes. C’est aujourd’hui une radio associative de catégorie A. Cette catégorie correspond à un grand nombre de radios (environ 600), mais celles-ci sont peu étudiées. Enfin, c’est une radio New Age et l’un des seuls médias audiovisuels français New Age. Croisant histoire et sociologie du religieux, des médias, de la communication, de la politique, des sciences, cette thèse repose sur une écoute assidue, sur de nombreux entretiens et discussions informelles, sur l’étude de différents fonds d’archives (papier, audio, numérique) et sur de nombreuses observations de type ethnographique. Nous donnons dans une première partie les outils scientifiques pour pouvoir analyser ce phénomène. Nous verrons ensuite dans quel contexte historique, radiophonique, économique, social, juridique et politique RIM fait son apparition et continue d’exister aujourd’hui. Enfin, nous nous focalisons sur le modèle radiophonique proposé, et sur les acteurs de cette radio. / In this thesis, we wonder how countercultural movement found new places of expression through the increased accessibility of audiovisual, thanks to "free radio" fight. Specifically, we want to know why and how society and the French media have enabled the establishment of an alternative media like Radio Ici et Maintenant (RIM) and how this radio has found a viable business model to spread its ideology. We shall see that the existence and persistence of RIM is due to the combination of two factors: firstly the reduction in the cost of entry into the radio broadcasting through the development and struggle of "free radio" that gave birth to associative radios (with their specific legal and economic model) and also the decrease in the cost of entering the religious market with the development of the French New Age counterculture issue of the American counterculture, itself the result of religious thoughts Western alternatives (related to the esoteric, the mediumship) and Eastern religions (Hinduism and Buddhism). Thus, the specific legal and economic model of associative radios allowed to live and persist "radiolibriste" and New Age ideology within RIM. But add that this model would not have been possible if it had not been worn by volunteer facilitators, invited activists and active listeners which we analyze the sociological profile. The scientific interest of this subject is the fact that it is mainly to study RIM which is an old "free radio". She was one of the most important radio stations in the movement. It is the oldest Parisian private local radio station. Today, it is a community radio (category A). This category corresponds to a large number of radio stations (about 600), but these are little studied. Finally, this is a New Age radio and one of the only French audiovisual media New Age. Crossing history and sociology of religion, media, communication, politics, science, this thesis is based on a constant listening, on numerous interviews and informal discussions on the study of different archives (paper, audio, digital) and numerous ethnographic observations. We give in the first part scientific tools to analyze this phenomenon. We will then see in which historical, radio, economic, social, legal and political context RIM appeared and continues to exist today. Finally, we focus on the proposed radio model and the actors of this radio.