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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Ultra narrow band based IoT networks / Réseaux IoT à bande ultra étroite

Mo, Yuqi 26 September 2018 (has links)
La compagnie Sigfox est reconnue comme un acteur prometteur pour des transmissions de longue-distance et faible consommation, dans le contexte de l'IoT. La modulation à bande ultra étroite (Ultra Narrow Band (UNB)), la technologie de communication choisie par Sigfox, permet de transmettre des informations dans des bandes de signal très étroites (typiquement 100 Hz). A cause de l'imprécision fréquentielle causée par les oscillateurs générateurs de fréquence, il n'est pas réaliste de transmettre des signaux UNB dans des canaux parfaitement orthogonaux. L'accès naturel au canal radio pour le système de UNB est de type ALOHA, avec un aspect aléatoire à la fois en en temps et en fréquence. Cet accès aléatoire peut introduire des collisions qui dégradent la performance du réseau. Le but de cette thèse est de caractériser la capacité des réseaux basés sur UNB, ainsi que d’améliorer la performance en considérant l'aspect aléatoire en temps et en fréquence. La première contribution de cette thèse, est une évaluation de la capacité en théorie et en simulation pour une seule station de base (BS), sous des conditions de canal idéaliste ou réaliste. En conditions idéalistes, nous avons exprimé la capacité pour le cas de l'ALOHA généralisé, et l'avons étendu aux cas de réplications. Pour les conditions réalistes, nous avons pris en compte l'interférence spectrale d'UNB et le path loss (sans et avec Rayleigh fading) afin de caractériser la performance des réseaux UNB, avec l'outil géométrie stochastique. La deuxième contribution est d'appliquer l’annulation successive d'interférence (SIC), qui nous permet d'atténuer les interférences, dans des réseaux de UNB. Nous avons fourni une analyse théorique de la performance des réseaux en considérant le SIC et l'interférence spectrale de UNB, pour le cas de mono-BS. La troisième contribution est l'amélioration de la performance des réseaux UNB, en exploitant la diversité de multi-BS. Nous avons fait une analyse théorique de performance en considérant multi-BS et selection combining (SC). En particulier, nous avons considéré que l’interférence vue par chaque BS est corrélée. Nous avons ainsi démontré mathématiquement que cette corrélation ne peut pas être supprimée dans des systèmes UNB. Ensuite, nous avons appliqué les technologies de la combinaison des signaux plus complexes comme MRC (max ratio combining) et EGC (equal gain combining), ainsi que le SIC à travers multi-BS. Nous avons évalué l'amélioration de performance que chaque technologie apporte, et les avons comparées. Nous avons souligné l'efficacité de ces technologies qui nous permettent d’obtenir des gains importants comparés au cas mono-BS (e.x. 125 fois plus de réduction d'erreur avec SIC globale). La dernière contribution est une validation expérimentale du modèle d'interférence spectrale de UNB, ainsi que la capacité des réseaux UNB, sur un testbed de radio FIT/Cortexlab. / Sigfox rises as a promising candidate dedicated for long-distance and low-power transmissions in the IoT backgrounds. Ultra Narrow Band (UNB), being the communication technology chosen by Sigfox, allows to transmit information through signals whose bandwidth is very limited, typically 100 Hz. Due to the imprecision restraint on electronic devices, it is impossible to transmit UNB signals in orthogonal channels. The natural radio access for this kind of system is thus random ALOHA, in both time and frequency domain. This random access can induce collisions which degrades the networks performance. The aim of this thesis is to characterize the capacity of UNB based networks, as well as to enhance its performance, by considering the randomness in time and frequency. The first contribution of the thesis, is the theoretical and numerical capacity evaluation under idealized and realistic channel conditions, for mono base station (BS) case. Under idealized conditions, we have quantified this capacity for generalized ALOHA case and extended for replications. We highlight the time-frequency duality in UNB systems, and that there exists an optimum replication number for a given network parameter set. Under realistic conditions, we have taken into account the specific spectral interference of UNB systems and propagation path loss (without and with Rayleigh fading) to characterize the performance, with the aid of stochastic geometry. The second contribution is the enhancement of UNB network performance in single BS case. We propose to use successive interference cancellation (SIC) in UNB networks, which allows to mitigate the interference. We have provided a theoretical analysis by considering both SIC and the spectral interference, for mono-BS case. We bring to light the efficiency of SIC in enhancing UNB system performance. The third contribution is the improvement of UNB systems, by exploiting the multiple BS diversity. An analytical performance evaluation considering the simplest selection combining is conducted. In particular, we consider the interference viewed by all the BSs are correlated. Then we apply more complex signal combining technologies such as MRC (max ratio combining) and EGC (equal gain combining), and even interference cancellation across multi-BS in UNB networks. We evaluate the performance improvement that each technology can bring, and compare them with each other. We highlight the efficiency of these multi-BS technologies which allow us to achieve significant performance enhancement compared to mono-BS (e.x. 125 times better performance with global SIC). Last but not least, we experimentally verify the the spectral interference model and network capacity on a cognitive radio testbed.
12

Estimativa da PER, protocolo de coleta de RSSI e determina??o de melhores rotas em RSSF / Estimate PER, protocol for RSSI collection and determination of best routes

Pereira, Vitor Queiroz 23 June 2016 (has links)
Submitted by Fernanda Ciolfi (fernanda.ciolfi@puc-campinas.edu.br) on 2016-08-11T19:28:00Z No. of bitstreams: 1 Vitor Queiroz Pereira.pdf: 3873709 bytes, checksum: 35cd48e3c95401712d40707f6b9e1af3 (MD5) / Made available in DSpace on 2016-08-11T19:28:00Z (GMT). No. of bitstreams: 1 Vitor Queiroz Pereira.pdf: 3873709 bytes, checksum: 35cd48e3c95401712d40707f6b9e1af3 (MD5) Previous issue date: 2016-06-23 / The characteristics of the Sensors Wireless Networks (WSNs) make this technology a solution for a variety of purposes, including when it comes to Internet of Things (IoT). Formed by sensor nodes, this type of network is responsible for monitoring and acting on various aspects of the environment to measure temperature or trigger an exhaust fan. However, wireless communication is vulnerable environment changes in which it operates, which could compromise the effectiveness of communication. Thus, this work presents a proposal for a methodology to determine optimal routes based on an estimate of the PER by the RSSI and a protocol for the collection of network RSSIs. The estimated PER was developed by experimental tests with FSK modulation. The collection protocol was implemented in a real network and RSSIs used to determine the best routes. The methodology for allocation of routes was developed with the classification premise of us according to the criticality of your application into two groups, high and low criticality. / As caracter?sticas das Redes de Sensores Sem Fio (RSSF) fazem desta tecnologia uma solu??o para diversas finalidades, inclusive quando se trata de Internet das Coisas (IoT). Formada por n?s sensores, este tipo de rede ? respons?vel por monitorar e atuar em diferentes aspectos do ambiente, como medir a temperatura ou acionar um exaustor. Entretanto, a comunica??o sem fio ? vulner?vel as mudan?as do ambiente em que est? inserida, podendo comprometer a efic?cia da comunica??o. Neste sentido, este trabalho apresenta uma proposta uma de metodologia para determina??o de melhores rotas baseada em uma estimativa da PER pela RSSI e um protocolo para a coleta das RSSIs da rede. A estimativa da PER foi desenvolvida por meio de testes experimentais com a modula??o FSK. O protocolo de coleta foi implementado em uma rede real e as RSSIs utilizadas na determina??o de melhores rotas. A metodologia para atribui??o de rotas foi desenvolvida baseada na classifica??o dos n?s em fun??o de sua criticidade.
13

Exploring tracing and tracking technologies to improve production efficiency and product quality.

Zakir Hussain, Tharik, Manavalan, Paul Johny January 2023 (has links)
The door manufacturing industry still heavily relies on manual technology for its production and quality assurance systems, which poses certain challenges. However, in recent years, the industry has witnessed a growing demand for personalized products, leading to a need for more adaptable production methods and shorter product life cycles. Unfortunately, this reliance on manual technologies has resulted in increased errors and inaccuracies. Moreover, manual technology requires significant time and effort investment, which reduces production efficiency and product quality. To address these issues, the purpose of this thesis is to address the issue of inefficiency at a door manufacturing company by examining its existing production systems and quality assurance system. The thesis aims to provide recommendations for improvement by exploring the integration of automated tracing and tracking technology. Furthermore, it would result in recommendations for feasible methods that may be used in Swedish production systems, as well as further study fields.

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