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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.
1

ANNOS : analysis of a communication system /

Duenki, Ann. January 1981 (has links)
Diss. no. 6770 techn. sc. SFIT Zurich. / Bibliogr.: p. 85-88.
2

Dynamic security in communication systems /

Caronni, Germano. January 1999 (has links)
Diss. no. 13156 techn. sc. SFIT Zurich. / Im Buchh.: Aachen : Shaker. Literaturverz.
3

A Data-centric Internet of Things Framework Based on Public Cloud

Liu, Yu January 2019 (has links)
The pervasive application of Internet of Things (IoT) has been seen in many aspects in human daily life and industrial production. The concept of IoT originates from traditional machine-to-machine (M2M) communications which aimed at solving domain-specific and applicationspecific problems. Today, the rapid progress of communication technologies, the maturation of Internet infrastructures, the continuously reduced cost of sensors, and emergence of more open standards, have witnessed the approaching of the expected IoT era, which envisions full connectivity between the physical world and the digital world via the Internet protocol. The popularity of cloud computing technology has enhanced this IoT transform, benefiting from the superior computing capability and flexible data storage, let alone the security, reliability and scalability advantages. However, there are still a series of obstacles confronted by the industry in deployment of IoT services. First, due to the heterogeneity of hardware devices and application scenarios, the interoperability and compatibility between link-layer protocols, sub-systems and back-end services are significantly challenging. Second, the device management requires a uniform scheme to implement the commissioning, communication, authorization and identity management to guarantee security. Last, the heterogeneity of data format, speed and storage mechanism for different services pose a challenge to further data mining. This thesis aims to solve these aforementioned challenges by proposing a data-centric IoT framework based on public cloud platforms. It targets at providing a universal architecture to facilitate the deployment of IoT services in massive IoT and broadband IoT categories. The framework involves three representative communication protocols, namely WiFi, Thread and Lo-RaWAN, to enable support for local, personal, and wide area networks. A security assessment taxonomy for wireless communications in building automation networks is proposed as a tool to evaluate the security performance of adopted protocols, so as to mitigate potential network flaws and guarantee the security. Azure cloud platform is adopted in the framework to provide device management, data processing and storage, visualization, and intelligent services, thanks to the mature cloud infrastructure and the uniform device model and data model. We also exhibit the value of the study by applying the framework into the digitalization procedure of the green plant wall industry. Based on the framework, a remote monitoring and management system for green plant wall is developed as a showcase to validate the feasibility. Furthermore, three specialized visualization methods are proposed and a neuron network-based anomaly detection method is deployed in the project, showing the potential of the framework in terms of data analytics and intelligence.
4

How Effective is RFID Shielding?

Öhrlund, Erik January 2019 (has links)
No description available.
5

Digital Compensation of Phase Noise Caused by Mechanical Vibrations

Mahmud, Akib January 2019 (has links)
The component that generates the frequency of the radio waves transmitted by a radar is generally built around a quartz crystal oscillator. When this component is exposed to mechanical vibrations, such as acceleration or rotation in different directions, phase noise occurs. That is due to the piezoelectric effect of quartz crystals, which eventually degrades the performance of a radar. High frequency noise are compensated for using mechanical dampers. However, the low frequency noise remains and requires a digital solution. To solve this, a theoretical compensation model for the quartz crystal has been designed. It was possible to measure the noise generated by the quartz crystal by utilising an accelerometer, perform simulations and calculations. With the help of these different tools, it was possible to theoretically calculate and reduce the phase noise by 30-40%. All the results that has been obtained are theoretical results and nothing has yet been implemented in any radar system.
6

VR som komplement i projekteringsfasen

Karlsson, Patrik, Larsson, Oscar, Widéen, Sebastian January 2018 (has links)
I examensarbetet undersöks användningen av VR som komplement i projekteringsfasen. Arbetet syftar till att skapa en smidig inkörningsfas, testa tekniken på ett verkligt projekt samt att hitta ett koncept kring utrustning, mjukvaror och hårdvaror som är lämpligt för BSV Arkitekter & Ingenjörer samt liknande företag. Problemet som arbetet grundar sig i är att få antal företag använder VR eftersom branschen är konservativ men också för att tekniken är relativt ny. I arbetet har metoder som intervjuer, litteratursökning och tester använts. I resultatet finns personliga intervjuer, teoretisk data, tester av utrustning och test av VR på ett verkligt projekt. Teknikens tillämpning på ett verkligt projekt gjorde undersökningen unik och givande för företag som är intresserade av att testa tekniken. Nyckelord: Virtual Reality (VR), Projekteringsfas, Kommunikation, Byggbranschen
7

Resource Allocation for Max-Min Fairness in Multi-Cell Massive MIMO

van Chien, Trinh January 2017 (has links)
Massive MIMO (multiple-input multiple-output) is considered as an heir of the multi-user MIMO technology and it has recently gained lots of attention from both academia and industry. By equipping base stations (BSs) with hundreds of antennas, this new technology can provide very large multiplexing gains by serving many users on the same time-frequency resources and thereby bring significant improvements in spectral efficiency (SE) and energy efficiency (EE) over the current wireless networks. The transmit power, pilot training, and spatial transmission resources need to be allocated properly to the users to achieve the highest possible performance. This is called resource allocation and can be formulated as design utility optimization problems. If the resource allocation in Massive MIMO is optimized, the technology can handle the exponential growth in both wireless data traffic and number of wireless devices, which cannot be done by the current cellular network technology. In this thesis, we focus on two resource allocation aspects in Massive MIMO: The first part of the thesis studies if power control and advanced coordinated multipoint (CoMP) techniques are able to bring substantial gains to multi-cell Massive MIMO systems compared to the systems without using CoMP. More specifically, we consider a network topology with no cell boundary where the BSs can collaborate to serve the users in the considered coverage area. We focus on a downlink (DL) scenario in which each BS transmits different data signals to each user. This scenario does not require phase synchronization between BSs and therefore has the same backhaul requirements as conventional Massive MIMO systems, where each user is preassigned to only one BS. The scenario where all BSs are phase synchronized to send the same data is also included for comparison. We solve a total transmit power minimization problem in order to observe how much power Massive MIMO BSs consume to provide the requested quality of service (QoS) of each user. A max-min fairness optimization is also solved to provide every user with the same maximum QoS regardless of the propagation conditions. The second part of the thesis considers a joint pilot design and uplink (UL) power control problem in multi-cell Massive MIMO. The main motivation for this work is that the pilot assignment and pilot power allocation is momentous in Massive MIMO since the BSs are supposed to construct linear detection and precoding vectors from the channel estimates. Pilot contamination between pilot-sharing users leads to more interference during data transmission. The pilot design is more difficult if the pilot signals are reused frequently in space, as in Massive MIMO, which leads to greater pilot contamination effects. Related works have only studied either the pilot assignment or the pilot power control, but not the joint optimization. Furthermore, the pilot assignment is usually formulated as a combinatorial problem leading to prohibitive computational complexity. Therefore, in the second part of this thesis, a new pilot design is proposed to overcome such challenges by treating the pilot signals as continuous optimization variables. We use those pilot signals to solve different max-min fairness optimization problems with either ideal hardware or hardware impairments.
8

HyperTransport - ein neues On-Board Kommunikationssystem

Franke, Maik 02 July 2003 (has links) (PDF)
Workshop Mensch-Computer-Vernetzung
9

Konzeption eines Managementsystems für die Nutzung von internen sowie externen Wissen zur Generierung von Innovationen /

Wissel, Gerald. January 2001 (has links)
Göttingen, Universität, Thesis (doctoral), 2001.
10

LTE Mobile Network performance with Antenna Tilt considering Real Radiation Patterns

Ruiz, Alberto Camach January 2015 (has links)
Due to the increasing demand of traffic, mobile networks requires flexibility to modify the area of service at any time. The use of antenna tilt is a crucial element in the design of modern networks as this element can modify the area of served cell and affects several parameters like coverage capacity or energy. The tilt of antennas automatically with remote electrical tilt (RET) is particularly relevant due to new smart networks that require the control of the system remotely. However, RET has limitations as a result of the imperfections of the design of real antennas. This is due to the fact that the whole pattern can vary for each tilt iteration. This study proposes a system level simulation of two real antennas with similar characteristics like gain, beam width and frequency, in order to evaluate the results in terms of coverage and capacity for different degrees of tilt. The results show that remote electrical tilt improves both coverage and capacity up to 32% and 50% respectively. However the performance of both the antennas differ. For example, different sizes of networks are simulated and different degree of optimum tilt is obtained for each antenna, which is explained by the comparison of the radiation patterns. The difference between the angles of the optimum tilt for different sizes of the network also affects to the energy efficiency metrics that have been simulated. One type of antenna shows better effects when tilt is applied and the energy efficiency improves up to 13% with respect to the other antenna. Through the comparison of the radiation pattern, it is possible to conclude which elements are the most important for different areas of coverage of the network. The high gain and the roll off of the main beam play an important role for cell edge coverage. In addition, sharp roll-off inclination and higher gain are the elements which have the strongest influence on tilt. Finally, the effect of side lobe levels on other parameters of the network is shown in this study. Lower side lobe level affects the areas closer to the base station and upper side lobe level interfere the adjacent cell. This study shows how these levels change for each tilt iteration and, thus, explains the difference in the performance of both antennas.

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