Дисертації: "Link Resolver"

1

Biolek, Martin. "Klientská aplikace protokolu DNS s grafickým rozhraním pro účely výuky." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2021. http://www.nusl.cz/ntk/nusl-442404.

Повний текст джерела

Анотація:

The goal of the Master thesis on the topic of the Client application of DNS protocol with graphical interface for teaching purposes is to create a program with the features of sending, receiving DNS, MDNS and LLMNR protocols with optional parameters. Additionally, compare the created application with available tools such as Nslookup, Dig and create examples of application for teaching.

Стилі APA, Harvard, Vancouver, ISO та ін.

2

Larsson, Caroline, and Sofie Johansson. "The Line-Manager as a Crucial Link During an Organizational Change." Thesis, Örebro universitet, Institutionen för juridik, psykologi och socialt arbete, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-88858.

Повний текст джерела

Анотація:

Earlier studies have identified factors that could be a threat to an employee'swell-being, performance, and motivation during an organizational change.However, there is a lack of research on hierarchical management organizationsand a line-manager's part of how a change is delivered to employees. With theuse of self-determination theory as a basis, this study examined a top-manager'smotivation style towards their line-managers, in the context of anorganizational change, and whether the line-manager's basic psychologicalneeds are satisfied. The hypothesis for the present study expresses: A linemanager'slevel of satisfaction with its basic psychological is associated withits top-manager's motivation style orientation. The sample (N= 52) consists oftwo levels of management, top-managers, and line-managers, and this studyshows a between-subject effect, and a within-subject effect, where, based onmotivation style, the rating on experienced satisfaction and frustration aredifferent. The proposal for further research suggests taking all the differenthierarchical management levels into account during an organizational change.
Tidigare studier har identifierat faktorer som kan hota anställdasvälbefinnande, prestation och motivation under en organisationsförändring.Det saknas dock forskning inom organisationer med ett hierarkiskt ledarskapoch linjechefens roll i hur en förändring levereras till anställda. Med selfdeterminationtheory som grund undersöker denna studie en toppchefsmotivationsstil gentemot sina linjechefer, under en omorganisation, och ifallderas grundläggande psykologiska behov är uppfyllda. Hypotesen för denaktuella studien är följande: linjechefens upplevelse av att ha autonomi,samhörighet, och kompetens tillfredställt har en association med derastoppchefs motivationsstil. Urvalet (N= 52) består av två nivåer av ledning,toppchefer och linjechefer. Resultatet visar en effekt både mellan och inomgrupperna, där upplevd tillfredsställelse och frustration är olika baserat påmotivationsstil. Förslag till senare forskning föreslås att ta hänsyn till allanivåer i en hierarkisk ledning under en organisationsförändring.

Стилі APA, Harvard, Vancouver, ISO та ін.

3

Rinaldi, Claudia. "Link-Layer Error Recovery Techniques to improve TCP Performance over Wireless Links." Thesis, KTH, Reglerteknik, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-109460.

Повний текст джерела

Анотація:

Recent technology has involved TCP in wireless applications even if it was originally designed to work over wired links. It is well known that wireless links are usually characterized by phenomena like shadowing, multipath propagation and path loss that cause an increase in the bit error rate. Moreover,TCP protocol was supposed to interpret all the losses as due to congestion because of it was designed to work over wired networks. All these problems caused by the wireless application of TCP usually degrade TCP performances. In order to improve TCP behavior over wireless links several solutions have been proposed in literature as: the split connection approach, the end-to-end approach and the link-layer approach. Starting from the link-layer solution that have been studied by Barman and Matta, the main contribution of this thesis is the study of the effects of different modulation formats on the maximum achievable value of an objective function, defined as the ratio between the TCP throughput and a cost function. Appropriate power management and error correction techniques are assumed to improve the link reliability observed by TCP and increase the objective function performance accordingly.

Стилі APA, Harvard, Vancouver, ISO та ін.

4

Henriksen, Øystein. "Path-searching for Rolling Motion of the Two-Link Acrobot With Curved Links." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for teknisk kybernetikk, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-16775.

Повний текст джерела

Анотація:

Mathematical models are designed for the Acrobot with Curved Links. From these models, the reduced system dynamics are derived, and used for a numerical search routine which aims to find a closed trajectory of a rolling motion without impact.

Стилі APA, Harvard, Vancouver, ISO та ін.

5

Morrison, Heather. "The dramatic growth of open access : implications and opportunities for resource sharing." Haworth Press, 2006. http://hdl.handle.net/2429/953.

Повний текст джерела

Анотація:

The Open Access movement seeks to make scholarly, peer-reviewed journal articles freely available to anyone, anywhere over the World Wide Web. There were some very significant developments in the area of Open Access (OA) in 2004, including statements by major funders in support of Open Access. There are now so many Open Access scholarly journal articles freely available, that, in the author’s opinion, being aware of, and using, the resources and related tools is now essential for libraries. Libraries can provide more resources faster for users by supplementing paid resources with ones that are Open Access. Library resources, such as link resolvers, are beginning to incorporate Open Access materials and web searches for Open Access materials. For example, the reSearcher software suite includes Open Access collections along with subscription-based resources in the CUFTS journals knowledgebase, and a web search for an Open Access copy of an article in the GODOT link resolver. SFX also incorporates Open Access journals. After exhausting more traditional resources, interlibrary loans staff are beginning to include Google searching in their workflow. This article will discuss what Open Access is, the dramatic growth of Open Access, and major collections, resources and tools. Implications, issues, and leadership opportunities for resource sharing specialists will be explored.

Стилі APA, Harvard, Vancouver, ISO та ін.

6

Eliasson, Cecilia. "Intensities as Tools in Grouting Evaluations - Using Data from the North Link and Stockholm City Line." Thesis, KTH, Jord- och bergmekanik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-92557.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

7

Cohen, D. H., M. A. Leutenegger, and R. H. D. Townsend. "Quantitative analysis of resolved X-ray emission line profiles of O stars." Universität Potsdam, 2007. http://opus.kobv.de/ubp/volltexte/2008/1811/.

Повний текст джерела

Анотація:

By quantitatively fitting simple emission line profile models that include both atomic opacity and porosity to the Chandra X-ray spectrum of ζ Pup, we are able to explore the trade-offs between reduced mass-loss rates and wind porosity. We find that reducing the mass-loss rate of ζ Pup by roughly a factor of four, to 1.5 × 10−6 M⊙ yr−1, enables simple non-porous wind models to provide good fits to the data. If, on the other hand, we take the literature mass-loss rate of 6×10−6 M⊙ yr−1, then to produce X-ray line profiles that fit the data, extreme porosity lengths – of h∞ ≈ 3 R∗ – are required. Moreover, these porous models do not provide better fits to the data than the non-porous, low optical depth models. Additionally, such huge porosity lengths do not seem realistic in light of 2-D numerical simulations of the wind instability.

Стилі APA, Harvard, Vancouver, ISO та ін.

8

Ekahana, Sandy Adhitia. "Investigation of topological nodal semimetals through angle-resolved photoemission spectroscopy." Thesis, University of Oxford, 2018. http://ora.ox.ac.uk/objects/uuid:afed6156-7aa2-4ba9-afd1-af53d775494f.

Повний текст джерела

Анотація:

Nodal semimetals host either degenerate points (Dirac/Weyl points) or lines whose band topology in Brillouin zone can be classified either as trivial (normal nodal semimetals) or non trivial (topological nodal semimetals). This thesis investigates the electronic structure of two different categories of topological nodal semimetals probed by angleresolved photoemission spectroscopy (ARPES): The first material is Indium Bismuth (InBi). InBi is a semimetal with simple tetragonal structure with P4/nmm space group. This space group is predicted to host protected nodal lines along the perpendicular momentum direction at the high symmetry lines of the Brillouin zone boundary even under strong spin-orbit coupling (SOC) situation. As a semimetal with two heavy elements, InBi is a suitable candidate to test the prediction. The investigation by ARPES demonstrates not only that InBi hosts the nodal line in the presence of strong SOC, it also shows the signature of type-II Dirac crossing along the perpendicular momentum direction from the center of Brillouin zone. However, as the nodal line observed is trivial in nature, there is no exotic drumhead surface states observed in this material. This finding demonstrates that Dirac crossings can be protected in a non-symmorphic space group. The second material is NbIrTe₄ which is a semimetal that breaks inversion symmetry predicted to host only four Weyl points. This simplest configuration is confirmed by the measurement from the top and bottom surface of NbIrTe₄ showing only a pair of Fermi arcs each. Furthermore, it is found that the Fermi arc connectivity on the bottom surface experiences re-wiring as it evolves from Weyl points energy to the ARPES Fermi energy level. This change is attributed to the hybridisation between the surface and the bulk states as their projection lie within the vicinity of each other. The finding in this work demonstrates that although Fermi arcs are guaranteed in Weyl semimetals, their shape and connectivity are not protected and may be altered accordingly.

Стилі APA, Harvard, Vancouver, ISO та ін.

9

Sun, Antonia Rujia. "Macrophage-mediated synovial inflammation is a key link to obesity-associated osteoarthritis." Thesis, Queensland University of Technology, 2018. https://eprints.qut.edu.au/123711/1/Antonia%20Rujia_Sun_Thesis.pdf.

Повний текст джерела

Анотація:

Obesity has been attributed in a major risk factor for developing and accelerating disease progression in osteoarthritis. To date, there is a lack of clinically proven therapies to halt osteoarthritis, the developments of such therapies are therefore a national as well as an international research priority. This research provides a new overview of the involvement of synovitis in promoting the destruction of synovial joints in obesity-induced osteoarthritis and might therefore by used as a therapeutic strategy for the development of disease-modifying anti-osteoarthritis drugs.

Стилі APA, Harvard, Vancouver, ISO та ін.

10

Dale, Anders. "Bærebølgegjenvinning i radio-link." Thesis, Norwegian University of Science and Technology, Department of Electronics and Telecommunications, 2009. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-10508.

Повний текст джерела

Анотація:

Denne masteroppgaven tar for seg et problem fremsatt av Kongsberg Defence & Aerospace. KDA ønsker i en digital radiolinje-link å operere ved 10 dB signal-støyforhold på inngangen til mottakeren. Dette skaper problemer for den gjeldende bærebølgegjenvinningen som fungerer ned til 13 dB. Bærebølgegjenvinneren består av en analog frekvensestimator etterfulgt av en digital faseestimator, hvor det er faseestimatoren som ifølge KDA ikke klarer å operere tilfredsstillende. Kravet for tilfredstillende operasjon ved 10 dB SNR er 2 grader RMS-fasefeil. Den gjeldende løsningen for faseestimering er Costas sløyfe med et 2. ordens filter. I denne masteroppgaven blir det foreslått to metoder for faseestimering. Den første baserer seg på ML-estimator med detekterte symboler, men har et tillegg for å kompensere for frekvensvariasjoner ut fra frekvensestimatoren i forkant. Dette tillegget lagrer faseestimat ut fra ML-estimatoren, og bruker lineær regresjon for å regne ut frekvensavviket. Det vises at dette systemet ikke fungerer tilfredsstillende ved 10 dB SNR. Den andre metoden er en tilleggsmodul kalt selektiv oppdatering. Denne modulen oppdaterer kun faseestimatet hvis en punktprøve er nær nok til et konstellasjonspunkt, hvis ikke blir punktprøven ignorert av faseestimatoren. Det vises teoretisk at denne metoden gir lavere symbolfeilsannsynlighet, men i simulerte systemer fungerer den ikke tilfredstillende. Denne modulen for selektiv oppdatering av faseestimatoren har blitt testet både med både ML-estimator og Costas sløyfe, og i begge tilfellene gir den dårligere faseestimat. Dette viser at gevinsten ved sikrere punktprøver går bort i færre punktprøver brukt i estimeringen. Det blir også foretatt en analyse av KDAs gjeldende faseestimator. Det vises både teoretisk og ved simulering at de opprinnelige filterparametrene brukt av KDA i Costas sløyfe gir et underdempet system. Forslaget til nye parametre er gamma = 2^-7 og rho = 2^-8. Disse parametrene har et forholdsvis raskt innsvingningsforløp, men er bare 0,25 grader over kravet på 2 grader RMS-fasefeil.

Стилі APA, Harvard, Vancouver, ISO та ін.

11

Nowotnick, Melanie. "The Environmental-Financial Performance Link." Thesis, Mid Sweden University, Department of Social Sciences, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-8413.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

12

Jacobsson, Magnus. "Khovanov homology and link cobordisms /." Uppsala : Matematiska institutionen, Univ. [distributör], 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-3765.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

13

Brostedt, Love. "A link to public space." Thesis, Umeå universitet, Arkitekthögskolan vid Umeå universitet, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-71658.

Повний текст джерела

Анотація:

Women in Dharavi have little social space except for their homes, in contrast to the menwho seem to be everywhere in the public space. If the status of women are to increase, theyalso need access to the public space.This project focuses on the interaction between women in common space in connectionto the homes and the public spaces in between. Common yards/gardens in between theunits are shared by four households creating a semi-private space. As the men are working,the women at home will take care of the garden and have a possibility to socialize withwomen from the other households.These common gardens have a clear visual connection to the public spaces, which areconnected to different play areas (playground does not seem to be the right word). As thewomen take their children to kindergarden or school they pass through the public space and can stay there to watch the children while they are playing. The children gives the women areason to be in public space. The women gives each other a reason to stay.

Стилі APA, Harvard, Vancouver, ISO та ін.

14

Poggi, Daniele. "Physical modeling of optical modulators for optical link analysis : Optical link analysis in silicon photonics technologies." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-247887.

Повний текст джерела

Анотація:

According to the 2018 Ethernet Roadmap projections, the requirements for high speed links keep increasing every year, always keeping an eye on the energy per bit consumption of the communication system. The Ethernet requirements are estimated to reach 1Tbps by 2022-2025. Optical links are one of the most concrete solutions to satisfy bandwidth requirements at low energy consumption. An optical link is a communication system that consists of a single end-to-end optical circuit. In contrast with vertical-cavity surface-emitting laser (VCSEL) technology, which is based on a direct laser modulation, silicon photonics technology (SPT) is based on indirect modulation. In order to perform the modulation, electro-optical modulators are needed in the optical link system for electrically modulating the optical power.This master thesis, developed at imec, will present the modeling of two different technologies of optical modulators: Silicon Ring Modulator and the Franz-Keldysh ElectroAbsorption Modulator. The work was initiated, since there were no available models of these devices in the actual framework for link analysis. First a preliminary study of the physical principles of the two devices was performed, in order to build the Matlab models. Then, these models were fitted with measurements, in order to adjust them to real-life behavior. After having obtained two working models of the two modulators, an alreadyexisting framework was used, to compare the energy consumption per bit in the optical link. However, the results obtained with the simulation didn’t highlight a technology to be preferred to the other.
Enligt prognoserna från Ethernet Roadmap 2018 fortsätter kraven på höghastighetslänkar att öka varje år och håller alltid ett öga på kommunikationssystemets energi konsumtion per bit. Ethernet-kraven beräknas nå 1Tbps 2022-2025.Optiska länkar är en av de mest konkreta lösningarna för att tillgodose bandbreddskrav vid låg energiförbrukning. En optisk länk är ett kommunikationssystem som utgör en punkt till punkt förbunden optisk krets. I motsats till teknik som utnyttjar den vertikala kavitetsytemitterande lasern (VCSEL), som bygger på en direkt lasermodulering, baseras kisel fotonikteknik (SPT) på indirekt modulering. För att utföra en modulering behövs elektrooptiska modulatorer i det optiska länksystemet för att elektriskt modulera den optiska effekten.Denna masteruppsats, utvecklad vid imec, kommer att presentera modelleringen av två olika teknologier av optiska modulatorer: Silicon Ring Modulatorn och Franz-Keldysh Electro Absorption Modulator. Arbetet, genomfördes eftersom det inte fanns några tillgängliga modeller av dessa enheter i själva ramverket för länkanalys. För det första genomfördes en preliminär studie av de två enheternas fysikaliska principer för att bygga Matlab-modellerna. Sedan jämfördes dessa modeller med mätningar för att anpassa dem till verkligt beteende. Efter att ha fått två arbetsmodeller av de två modulatorerna användes ett redan existerande ramverk för att jämföra energikonsumtionen per bit i den optiska länken. De resultat som erhölls med simuleringen indikerade emellertid inte någon teknik som skulle föredras framför den andra.

Стилі APA, Harvard, Vancouver, ISO та ін.

15

Seddigh, Sorosh. "Link QualityControl (LQC) i GPRS/EGPRS." Thesis, Linköping University, Department of Electrical Engineering, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-1761.

Повний текст джерела

Анотація:

This master thesis has been done at Enea Epact AB. The purpose of this thesis is to develop and implement a Link Quality Control algorithm for GPRS/EPGRS in the current testing tool. A Link Quality Control (LQC) shall take quality values from mobile stations and base stations and decide a codingsscheme that opimizes the throughput of data.

The Advantage with LQC is that it adapts the used coding scheme to the channel quality. If the channel quality is too bad for the used coding scheme, a slower coding scheme with more redundancy should be selected. On the other hand, if the channel quality is too good for the used coding scheme, LQC should recommend a faster coding scheme with less redundancy.

The testing tool is now using a static coding schme that doesn’t change during a data session. An LQC is therefore necessary for better simulation of the traffic and to make the tests more real.

Стилі APA, Harvard, Vancouver, ISO та ін.

16

Niskanen, Johan, and Andersson Joakim Gröndal. "The Eastern Link : A sustainable discourse?" Thesis, Department of Water and Environmental Studies, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-19311.

Повний текст джерела

Анотація:

The local newspapers in Sweden are often used as an arena where groups of different political leanings try to frame current events to suit their purposes. Therefore how the news media presents the discussed issue and how it relates to sustainable development are important for a democratic process. One of the largest infrastructural projects in Sweden currently is the Eastern Link and there are many economical, social and ecological concerns when constructing such a large infrastructural project. It is therefore important to look at how sustainable development is represented in the local news media when concerning this infrastructural project. The aim of this thesis is to study how the local media presents the Eastern Link project in relation to sustainable development and how it affects democracy. This thesis critically discusses the different parts of sustainable development; the impact of and on economical issues, social issues and ecological issues in relation to the study material. Both a quantitative approach and a qualitative approach are used as a method. The thesis also links the results of this study to previous research on communication and theories on sustainable development. The results show that neither of the newspapers Folkbladet or NT is presenting the Eastern Link in a balanced way from a sustainability perspective. A majority of the articles are focusing on the social discourse; this differs from previous research where the focus is on the economical discourse.

Стилі APA, Harvard, Vancouver, ISO та ін.

17

Johansson, Christian, and Marcus Karlsson. "Characterisation of a data transmission link." Thesis, Linköping University, Department of Science and Technology, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-2359.

Повний текст джерела

Анотація:

This report is the result of a Master Thesis work that has been performed between October 2003 and March 2004. The purpose of the work was to evaluate a part of the signal chain in a product of Micronic Laser Systems AB. The evaluation was performed to obtain the characterisation for the signal chain, such as impedances and crosstalk.

The work started with a literature study in order to refresh and increase the knowledge that was needed before the practical work. Then measurements, computer aided simulations and comparisons between these were performed.

Measurements were performed using TDR (Time Domain Reflectometry). The results showed the impedance levels along the signal chain. This was interesting since it showed how well the different parts in the system are matched. Unmatched parts result in reflections that disturb the transmitted signal and contribute to crosstalk, which also was measured.

Simulations were done using ADS (Advance Design System), a tool from Agilent Technologies Inc. A substantial part of the simulation work was to build models of the real system. These models have been used for simulation. The simulation results were then compared to the measurement results.

The results show that the system can be better matched concerning the channel impedance. There are large variations in impedance levels along the signal chain, resulting in signal reflections. Another effect studied is crosstalk between channels. Measurements and simulations showed the presence of crosstalk but it seems to be a minor problem in the current machine.

Стилі APA, Harvard, Vancouver, ISO та ін.

18

Berg, Andreas. "Canoo Link : From City to Nature." Thesis, Umeå universitet, Designhögskolan vid Umeå universitet, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-184364.

Повний текст джерела

Анотація:

People in cities have a need of recreation. Leisure activities are a big part of people’s health and well- being. Many leisure activities are practiced outside in the nature. Today many citizens do not own a car and public transportation fail to meet the peoples need to move out from the city center out into the wild nature. Public transportation run according to a certain timetable and an established route. They also come with restrictions of what you can bring on board. In other words, there is a need for agile transportation that transport people and their equipment from the city out to the nature; and the need will only increase as the urbanization continue. The whole idea of the project originated from the question, “How might future mobility adapt to fit people’s need for recreation?” The project started with a research. The author studied trends how cities will develop, what defines generation Z, how 6G can be used in the future transportation industry, how electrification changes the terms of car design, the current status of autonomous technology etc. The research also included Canoo, a car company that design, develop and build electric vehicles with focus on lifestyle, utility and sustainability. After completed research, the project moved into a creative phase which included analog sketches of the vehicle, testing of proportions in scale 1: 1 and a storyboard that describes how the vehicle can be used. When thecreative phase was done, the project moved to its final phase; visualization. A 3D model was constructed in Autodesk Maya, a polygonal modelling software, and rendered images of the 3D model was conducted with Autodesk VRED, a 3D visualization software. The project resulted in Canoo Link; Link, targeting year 2035, is an electric autonomous utility vehicle that you subscribe to. It can carry 4 passengers and has storage space to haul equipment and supplies for canoeing, mountain biking etc. With its robust design and high ground clearance it is ready to take on some tough terrain. The subscription offers the customer full disposal of the vehicle during the activities for convenience and security. It acts like a hub for your activities, not just as a vehicle for commuting. To summarize; Link is a design proposal of a vehicle that connect people living in cities to the nature. It is not just a car that takes you from one point to another, it is a lifestyle.

Стилі APA, Harvard, Vancouver, ISO та ін.

19

Daglaridis, Georgios Theodoros. "Radio Link Quality in Backscatter Communication." Thesis, Uppsala universitet, Institutionen för informationsteknologi, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-371561.

Повний текст джерела

Анотація:

The opportunities that the Internet of Things (IoT) offers impose the need of ultra low-power communication systems. For that, backscatter communication can be used, where the transmitting node consumes only a few tens of micro Watts. This is achieved because the node transmits only by selectively absorbing or reflecting existing RF signals generated by another IoT device. As a consequence, the backscattered signal is considerably degraded. The degradation of the signal along with the interference caused at the receiver by the original RF signal, result in reduced communication range.In the first part of this thesis we experimentally investigated the degradation in the quality of the backscatter radio link. Throughout the experiments we employed the frequency-shifted backscatter communication scheme where the backscatter tag generates its transmission shifted by a frequency offset from the interference of the original RF signals. The experimental results indicate that for frequency offset greater than 10 MHz the interference presented by these RF signals affects less the backscattered signal received 2, 3, or 4 IEEE 802.15.4 channels away.

Стилі APA, Harvard, Vancouver, ISO та ін.

20

Magnusson, Daniel. "A network based algorithm for aided navigation." Thesis, Linköpings universitet, Institutionen för systemteknik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-75235.

Повний текст джерела

Анотація:

This thesis is concerned with development of a navigation algorithm primarily for the aircraft fighter SAAB JAS 39 Gripen, in swarms of other units. The algorithm uses information from conventional navigation systems and additional information from a radio data link as aiding information, relative range measurements. As the GPS can get jammed, this group tracking solution can provide an increased navigation performance in these conditions. For simplicity, simplified characteristics are used in the simulations where simple generated trajectories and measurements are used. This measurement information can then be fused by using filter theory applied from the sensor fusionarea with statistical approaches. By using the radio data link and the external information sources, i.e. other aircraft and different types of landmarks with often good performance, navigation is aided when the GPS is not usable, at e.g. hostile GPS conditions. A number of scenarios with operative sense of reality were simulated for verifying and studying these conditions, to give results with conclusions.
Det här examensarbetet syftar till utveckling av en algoritm för navigering, primärt för stridsflygplanet SAAB JAS 39 Gripen, i svärmar av andra enheter. Algoritmen använder information från konventionella navigeringssystem och ytterligare information från en radiodatalänk som ger understödjande information, relativa avståndsmätningar. Då den förlitade GPS:en kan störas ut, kan denna gruppspårande lösning öka navigeringsprestandan i dessa förhållanden. För enkelhetens skull, används förenklade karaktäristiker i simuleringarna där enkla genererade trajektorier och mätningar används. Denna mätinformation kan sedan ihopviktas genom att använda filterteori från statistisk sensorfusion. Genom att använda radiodatalänkar och den tillförda informationen från externa informationskällor, således andra flygplan och olika typer av landmärken som väldigt ofta har god prestanda, är navigeringen understödd när GPS inte är användbar, t.ex. i GPS-fientliga miljöer. Ett antal scenarion med operativ verklighetsanknytning simulerades för att verifiera och studera dessa förhållanden, för att ge resultat med slutsatser.
© Daniel Magnusson.

Стилі APA, Harvard, Vancouver, ISO та ін.

21

Jamil, Faisal. "Microwave Wireless Communication Link Base Band Part." Thesis, Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-233.

Повний текст джерела

Анотація:

This thesis was completed as a part of the project "Microwave wireless Communication

Link". In this thesis, the requirements to develop base band part for the transceiver were

studied, including, usage of proper hardware equipment as well as software

programming. A signal injector performed as a hardware interface between the Analog

part and the Digital (base band) part of the tranceiver, whereas, a PCI card acted as a data

acquisition device for base band part. A programming language was required to build

such a software, able to successfully represent a transmitter and a receiver. All the

features were found in Labview (Laboratory Virtual Instrument Engineering Workbench)

introduced by National Instruments in 1980s. A modern version of Labview i.e. version

7.1, was used in this thesis, it views the software as a virtual instrument to automate and

measure the values passed from the connected hardware. Labview provides a graphical

development environment, which is modular and parallel in nature, and uses an efficient

G compiler. A coherent base band receiver using matched filter was implemented, and a

base band transmitter using NRZ-L digital encoding scheme and QPSK modulation

scheme was developed.

Стилі APA, Harvard, Vancouver, ISO та ін.

22

Ahsin, Tafzeel ur Rehman. "Cooperative Communications : Link Reliability and Power Efficiency." Doctoral thesis, KTH, Kommunikationssystem, CoS, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-61134.

Повний текст джерела

Анотація:

Demand for high data rates is increasing rapidly for the future wireless generations, due to the requirement ofubiquitous coverage for wireless broadband services. More base stations are needed to deliver these services, in order tocope with the increased capacity demand and inherent unreliable nature of wireless medium. However, this would directly correspond to high infrastructure costand energy consumption in cellular networks. Nowadays, high power consumption in the network is becoming a matter of concern for the operators,both from environmental and economic point of view. Cooperative communications, which is regarded as a virtual multi-input-multi-output (MIMO) channel, can be very efficient in combating fading multi-path channels and improve coverage with low complexity and cost. With its distributed structure, cooperativecommunications can also contribute to the energy efficiency of wireless systems and green radio communications of the future. Using networkcoding at the top of cooperative communication, utilizes the network resources more efficiently. Here we look at the case of large scale use of low cost relays as a way of making the links reliable, that directly corresponds to reductionin transmission power at the nodes. A lot of research work has focused on highlighting the gains achieved by using network codingin cooperative transmissions. However, there are certain areas that are not fully explored yet. For instance, the kind of detectionscheme used at the receiver and its impact on the link performance has not been addressed.The thesis looks at the performancecomparison of different detection schemes and also proposes how to group users at the relay to ensure mutual benefit for the cooperating users.Using constellation selection at the nodes, the augmented space formed at the receiver is exploited for making the links more reliable. Thenetwork and the channel coding schemes are represented as a single product code, that allows us to exploit the redundancy present in theseschemes efficiently and powerful coding schemes can also be designed to improve the link performance. Heterogeneous network deployments and adaptive power management has been used in order to reduce the overall energy consumption in acellular network. However, the distributed structure of nodes deployed in the network, is not exploited in this regard. Here we have highlightedthe significance of cooperative relaying schemes in reducing the overall energy consumption in a cellular network. The role of differenttransmission and adaptive resource allocation strategies in downlink scenarios have been investigated in this regard.It has been observed that the adaptive relaying schemes can significantly reduce the total energy consumption as compared to the conventionalrelaying schemes. Moreover, network coding in these adaptive relaying schemes, helps in minimizing the energy consumption further.The balance between the number of base stations and the relays that minimizes the energy consumption, for each relaying scheme is also investigated.
QC 20120124

Стилі APA, Harvard, Vancouver, ISO та ін.

23

Mustafa, Ali, Nasir Siddique, and Mubeen Zubair. "DATA LINK LAYER SECURITY PROBLEMS AND SOLUTIONS." Thesis, Högskolan i Halmstad, Akademin för informationsteknologi, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-27574.

Повний текст джерела

Анотація:

The Open Systems Interconnect Model (OSI) is a conceptual model of networking thatcategorizes network functions into seven layers. It is defined in this model that how layerscommunicate with each other. In this thesis, we address common Layer 2 attacks and theirsolutions. Layer 2 is considered a very weak link in a secure network. If the data is compromisedat Layer 2, it cannot be detected at other layers because each layer works without the knowledgeof other layers. We discuss Layer 2 weakness and vulnerability exploitation tools briefly. It isexplained how an attacker can exploit network by using different attack tools. Our results showthat these attacks are very productive if a network administrator does not implement propersecurity at Layer 2 in the OSI model. We propose solutions to secure Layer 2 devices and thesesolutions are implemented by using attack tools. Security configurations are deployed to combatagainst attacks and protect the integrity, confidentiality, and availability of the network traffic.

Стилі APA, Harvard, Vancouver, ISO та ін.

24

Asif, Muddassir. "Investigating Maximum Fiber Link Length with SEDFA." Thesis, KTH, Skolan för informations- och kommunikationsteknik (ICT), 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-119814.

Повний текст джерела

Анотація:

Fiber optic is one of the most rapidly growing technologies used these days for high bandwidth networks. This rapid growth in this area is resulting in production of cheaper and low power equipment. The objective of this study is to investigate the limitations of an optical network while using low cost and low power equipment. This study presents the analysis regarding the use of standard low cost fiber equipment to reach distances above 250 km for 1 Gbps networks and try to achieve more than 100 km for 10 Gbps fiber networks. The transceivers used for this study for 1 Gbps networks are rated to reach 150 km and for 10 Gbps the transceivers are made for 40 km. An EDFA (Erbium Doped Fiber Amplifier) is used to overcome the problems of low power. This study also presents an investigation regarding the placement of EDFA along the 1 Gbps and 10 Gbps links. This study is aimed at the rural areas of Somalia where power grids are not available in most of the region. Hence the tests have been performed to consider the use of solar power to run the amplifier. The results show that, by using a SFP transceiver built for 150 km and by the use of only one EDFA it is possible to achieve distances of maximum 310 km for 1 Gbps networks. This is possible due the use of an in-line amplifier placed after 150 km. The distance is limited to 310 km only because of the power limitation. For the 10 Gbps fiber link with XFP transceivers rated for 40 km, without use of amplifier, transmission was possible up to 75 km. After using an EDFA at 75 km, a distance of 125 km was achieved, but beyond that the dispersion was a limiting factor for the system. With the use of a dispersion compensating fiber unit, transmission was possible to a distance of 150 km. As the EDFA consumes very little power, approximately 1 W, the use of a solar panel to power the EDFA is a promising solution. According to the results even only four hours of effective sunshine is more than enough to charge the battery to run the low power amplifier. Even with multiple cloudy days the battery voltage was enough to power the EDFA.

Стилі APA, Harvard, Vancouver, ISO та ін.

25

Nilsson, Kim. "Reactive Networking using Dynamic Link Exchange Protocol." Thesis, KTH, Kommunikationsnät, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-154832.

Повний текст джерела

Анотація:

This master thesis studies the possibilities of using a radio-router protocol in order to increase the quality of service in dynamic tactical network environments. We cover three radio-router protocols with emphasis on Dynamic Link Exchange Protocol (DLEP). Many applications, such as voice and video communication, have bandwidth and latency requirements which need to be fulfilled in order to provide a sufficient level of quality. This poses a problem in tactical network environments where links are typically dynamic and both bandwidth andlatency can vary. A radio-router protocol can alleviate this problem and also improve the routing in a network by allowing routers to take part of link-layer information. By using a radio link emulator (RLE) developed by Saab we are able to simulate dynamic network environments. We have performed two experiments by combining the RLE and an implementation of a subset ofthe DLEP specification draft. Both experiments simulate typical military network scenarios and allow us to analyse the effects of utilizing link-layerfeedback.Our results show that by using DLEP it is possible to provide better quality of service in highly dynamic conditions. We also show that DLEP can influence Optimized Link State Routing (OLSR) by making OLSR aware of changes in the network topology. This leads to a reduced network convergence time with only a small increase in OLSR overhead.

Стилі APA, Harvard, Vancouver, ISO та ін.

26

Järpehult, Oscar, and Martin Lindblom. "Longitudinal measurements of link usage on Twitter." Thesis, Linköpings universitet, Institutionen för datavetenskap, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-159331.

Повний текст джерела

Анотація:

As Twitter launched with their unique way of limiting posts to only 140 characters the usage of link shorteners was brought forth. This was the only way to fit long URLs in tweets until Twitter solved this by providing their own integrated link shortener. This study investigates how links are used on Twitter. The study include both care fulldata collection including multiple APIs and analysis of the collected data providing new insight into this topic. It was found that a small set of internet domains account for a large part of the links found in posted tweets. This set of top occurring domains did not necessarily reflect the top domains typically on common internet top lists. When looking at link shorteners in posted tweets we found that “bit.ly” was the most common one. Due to our method of collecting data we had the possibility of looking up the amount of clicks “bit.ly” links had received. We compared the click data to the amount of retweets the tweets containing these links had received and this led to some interesting discoveries regarding the ratio between these two.

Стилі APA, Harvard, Vancouver, ISO та ін.

27

Huang, Mei-Ling [Verfasser], and Simon [Akademischer Betreuer] White. "Spatially-resolved star formation histories and molecular gas depletion time of nearby galaxies / Mei-Ling Huang. Betreuer: Simon White." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2015. http://d-nb.info/1076980805/34.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

28

Moström, Mathilda, and Alexander Edberg. "Longitudinal study of links, linkshorteners, and Bitly usage on Twitter." Thesis, Linköpings universitet, Institutionen för datavetenskap, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-168629.

Повний текст джерела

Анотація:

Social networks attract millions of users who want to share information and connect with people. One of those platforms are Twitter,which has the power to greatly shape people's opinions and thoughts. It is therefore important to understand how information is shared among users. In this thesis, we characterize the link sharing usage on Twitter, placing particular focus on third-party link shortener services that hide the actual URL from the users until the users click on a generic, shortened URL, focusing mainly on the link management platform Bitly. The purpose of this thesis is to analyze link usage among users over a specific time period, the domains that different users and link shortens direct their users to and compare the click rates of such links with the corresponding retweet rates to see how this vary over time. We use a measurement framework that is developed by two other students from Linköping University to collect datasets over different time periods. First, we will compare a one-week-long dataset from the spring of 2019 to one that is gathered one year later in the spring of 2020. Two additional one-week-long datasets has also been collected during the spring of 2020. We use the two main datasets, separated by a year, to evaluate long-term differences, and the three datasets from the spring of 2020 to analyze shorter-term variations in the link usage. The study highlights with this approach is to be able to highlight significant patterns over time, including with regard to what domains that are tweeted. We have found that the usage of URL link shorterns has not decreased over the last year, though the usage of specifically Bitly has done so. The top domains with highest occurrences from 2019 did not get to keep their high rankings in 2020, this is especially true for facebook.com whose occurrence has dropped by 2.7 percentage points in 2020. Our conclusion is that the difference between the years is not huge but that there are some interesting trends and patterns. Given the prevailing pandemic Covid-19, we have also chosen to do a minor analysis of how many users of Twitter link to domains related to this. It turned out that the link sharing of Covid-19 related substances decreased quite sharply during our analysis period.

Стилі APA, Harvard, Vancouver, ISO та ін.

29

Ahsin, Tafzeel ur Rehman. "Link Reliability in Cooperative Relaying Using Network Coding." Licentiate thesis, KTH, Kommunikationssystem, CoS, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-25942.

Повний текст джерела

Анотація:

Demand for high data rates is increasing rapidly for future wireless systems.This trend is due to the increase in the number of mobile subscribers that need bandwidth hungry multimedia applications anywhere, anytime. Fourth generation cellular systems like IMT-advanced are being developed to meet these requirements. The unreliable nature of the wireless medium is one of the main hinderance in providing high data rates. Cooperative communication in cellular networks is emerging as a new paradigm to deal with the channel impairments. User cooperation via fixed relays in cellular systems form multiple access relay channels (MARCs) and provide an effective and cost efficient solution to achieve spatial diversity gains. Network resources can be utilized efficiently by using network coding at cooperating nodes. A lot of research work has focused on highlighting the gains achieved by using network coding in MARCs. However, there are certain areas that are not fully explored yet. For instance, the kind of the detection scheme used at the base station receiver and its impact on the link performance has not been addressed. In most cases, the outage probability has been used as a performance measure of MARCs. However, it is well known that the outage probability gives information about the signal availability, but it does not give the complete picture about the reliability of the link and the achieved quality of service. This thesis work looks at the link performance, in terms of symbol error probability, of multiple access relay channels that employ network coding at the relay node. Different types of detection schemes are considered and their performance is compared under different link conditions. Analytical expressions for the average symbol error probability of the cooperating users are derived. Focusing on the uplink of cellular systems, certain rules are devised on how to group users at relay node to ensure mutual benefit for the cooperating users. As a way of improving the link performance of multiple access relay channels and their robustness, the thesis considers constellation selection for the different branches. This method takes advantage of the redundancy between the transmitted symbols created by network coding and the augmented signal space obtained at the base station receiver. The obtained results show that, with a proper selection of the constellation sets, the link performance of MARCs can be improved. The thesis further looks at the interaction between the channel coding schemes of the cooperating users and network coding. It is shown that joint channel-network coding in MARCs can be seen as a product code. This new representation provides considerable flexibility in selecting efficient decoding algorithms at the base station receiver and gives the possibility to use more powerful network coding schemes for MARCs.
QC 20101118
Sino-Swedish Cooperative Program: IMT-Advanced and Beyond

Стилі APA, Harvard, Vancouver, ISO та ін.

30

Uddin, Saif. "PLESIOCHRONOUS INTER-BOARD NETWORK-ON-CHIP COMMUNICATION LINK." Thesis, KTH, Skolan för informations- och kommunikationsteknik (ICT), 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-93801.

Повний текст джерела

Анотація:

High speed data communication has brought a monumental change in both the modern human experience and in the pace of technological advancements. Processing and communication of data are closely associated with each other and are accomplished normally through broadly termed processor-based systems. Traditional buses have become a bottleneck in these systems with ever increasing demands in speed and bandwidth. This is due to their inability to scale in parallel with the increasing resources, speed requirements and complexities. Network-on-Chip has offered a sustainable solution to this problem and is aimed to replace the traditional buses. This thesis presents multiple solutions to a multi-board Network-on-Chip Communication System for upgrading the data-rate several times through the links; and for eliminating a persistent breakdown of communication protocol. The thesis builds upon a 4x4 Network-on-Chip having 16 processor-nodes implemented on four interconnected plesiochronous Altera Stratix-II FPGA boards. Although the communication in on-chip network was fast and robust for obvious reasons, the Inter-board communication was incapable of high speed data transfer. It severely limited the performance of the whole Network-on-Chip and marred the advantages that it has over traditional bus-based systems. The thesis utilizes several optimizations and techniques to enable an error-prone wired-link to successfully transfer signals and clock at high speed. It also introduces a fault tolerance technique for accuracy of data transfer through the network and also reduces the logic size of the communication mechanism. It involves multi-pronged approach for the challenges posed by deteriorating clock and signal integrity towards a successful and desirable communication. A test system is also developed to investigate the problems restricting the clock rate, and to test the accuracy of the data transfer. The test system, being balanced in distribution of data, is applied to the original design as well as to the new solutions proposed.

Стилі APA, Harvard, Vancouver, ISO та ін.

31

Antelius, Daniel. "Link Extraction for Crawling Flash on the Web." Thesis, Linköpings universitet, Institutionen för datavetenskap, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-117604.

Повний текст джерела

Анотація:

The set of web pages not reachable using conventional web search engines is usually called the hidden or deep web. One client-side hurdle for crawling the hidden web is Flash files. This thesis presents a tool for extracting links from Flash files up to version 8 to enable web crawling. The files are both parsed and selectively interpreted to extract links. The purpose of the interpretation is to simulate the normal execution of Flash in the Flash runtime of a web browser. The interpretation is a low level approach that allows the extraction to occur offline and without involving automation of web browsers. A virtual machine is implemented and a set of limitations is chosen to reduce development time and maximize the coverage of interpreted byte code. Out of a test set of about 3500 randomly sampled Flash files the link extractor found links in 34% of the files. The resulting estimated web search engine coverage improvement is almost 10%.

Стилі APA, Harvard, Vancouver, ISO та ін.

32

Sunedahl, Björn. "Bidirectional Link Capacity Estimation in an IP Network." Thesis, KTH, Skolan för elektro- och systemteknik (EES), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-200603.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

33

Hammerin, Karl, and Ramona Streitenberger. "RTLS – the missing link to optimizing Logistics Management?" Thesis, Tekniska Högskolan, Högskolan i Jönköping, JTH, Industriell organisation och produktion, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-45264.

Повний текст джерела

Анотація:

The purpose of this thesis was to investigate how potentials of Real-Time Location Systems (RTLS) in relation to Just In Time (JIT) management could be utilized within logistics management. For this, a framework, based on previous research of the interrelations of RTLS and JIT management, is proposed, to assess the effects of RTLS on logistics management, both on a managerial - as well as on an operational level. To answer the proposed research questions, the study followed a deductive and exploratory case study design, which was conducted at a company within the automotive industry. To understand the challenges within logistics management at the case company, interviews, observations, analysis of internal documents and a focus group were used, which allowed for a triangulation of the captured information. The findings and analysis of the data show that on an operational level the challenges within logistics management are related to complex logistic structures, pull strategies with partial push material flows, lack of information and – reliable data, as well as processes reliant on individuals. On the managerial level the findings suggest challenges related to high complexity and space constraints, time constraints, lack of transparency and – data connections, the company's improvement focus, employee attitude and a lack of reliable data. When the challenges were evaluated in relation to the proposed framework, it shows that these challenges would be resolved or counteracted by the benefits RTLS could provide in relation to JIT management. This study thereby supports the positive correlation between RTLS’s potential and JIT in logistics management.

Стилі APA, Harvard, Vancouver, ISO та ін.

34

Alm, Maria. "Nationell kraft och lokal motkraft : en diskursanalys av konflikten kring SwePol Link /." Linköping : Tema teknik och social förändring, Linköpings universitet, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-6452.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

35

Costanzo, Deborah. "Probing the accretion/ejection flows in AGN by characterizing Fe K emission/absorption line variability with residual maps." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018. http://amslaurea.unibo.it/16361/.

Повний текст джерела

Анотація:

La dinamica e la geometria del materiale nelle vicinanze di un SMBH negli AGN sono ancora incerte, sia per quanto riguarda gli inflow sia per gli outflow, che possono essere responsabili del feedback da AGN sulla galassia ospite. L'analisi spettrale temporalmente risolta è fondamentale per studiare questi fenomeni e la banda energetica 4-10 keV è quella più adatta, in quanto vi si trova la riga di fluorescenza del ferro a 6.4 keV e, possibilmente, righe risonanti in assorbimento del ferro blueshiftate, indicative di venti da disco ultra-veloci. L'analisi adottata in questo lavoro di tesi si basa sulla tecnica dell'Excess Map, introdotta da Iwasawa et al. (2004). Lunghe esposizioni sono sezionate in intervalli temporali e ogni spettro risultante viene fittato con un semplice modello di continuo. I residui positivi sono quindi utilizzati per costruire un'immagine nel piano tempo vs. energia al fine di massimizzare la rivelazione di possibili strutture spettrali e derivarne l'evoluzione temporale. Laddove nelle Excess Map solo i residui positivi venivano considerati, tramite la nostra tecnica, denominata Residual Map, anche i residui negativi, legati a possibili strutture in assorbimento, vengono individuati e analizzati. Nel lavoro si è selezionato un campione di galassie di Seyfert 1 osservate con il satellite XMM-Newton, che garantisce la massima sensibilità nell'intervallo spettrale di interesse. Dal catalogo 3XMM-DR7 si sono scelte le sorgenti più brillanti nelle bande di interesse, NGC3783 e Mrk 509, e IRAS13224-3809, ossia quella con l'osservazione più lunga al momento disponibile, ma ad un livello di flusso inferiore. Nel lavoro ci si è focalizzati su un'osservazione particolarmente interessante tra quelle relative a NGC3783; in questa la riga del Ferro K_alpha mostra quattro picchi intervallati da circa 5-10 ks, corrispondenti ai tempi orbitali di un hot spot co-ruotante con il disco di accrescimento a distanze di circa 9-30 Rg.

Стилі APA, Harvard, Vancouver, ISO та ін.

36

Wålander, Natalie, and Jannie Andersson. "Event Marketing : Kulturnatten och City Art Link som marknadsföringsverktyg." Thesis, Linköping University, Linköping University, Linköping University, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-57476.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

37

Koneri, Kiran Kumar. "Implementation of Collection Tree Protocol over WirelessHART Data-Link." Thesis, Tekniska Högskolan, Högskolan i Jönköping, JTH, Data- och elektroteknik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-15665.

Повний текст джерела

Анотація:

Wireless Sensor Networks (WSNs) are ad-hoc wireless networks for small form-factor embedded nodes with limited memory, processing and energy resources. Certain applications, like industrial automation and real-time process monitoring requires time synchronized reliable network protocol. Current work for WSNs provides either time synchronized with low reliability (WirelessHART) or reliable network without time synchronization (Collection Tree Protocol). The Collection Tree Protocol (CTP) provides the reliability from 94.7% to 99.9% for CSMA-CA based MAC layer. This paper addresses channel hopping, a class of frequency diverse communication protocol in which subsequent packets are sent over different frequency channels. Channel hopping combats external interference and persistent multipath fading, two of the main causes of failure along a communication link. Channel hopping technique leads to a high reliable and efficient protocol which is specified by HART Communication Foundation and named as WirelessHART. WirelessHART Data-Link layer designed based on TDMA and CSMA-CA mechanism. By implementing the CTP over WirelessHART Data-Link layer, the reliability of the network protocol can be improved compare to actual CTP standard implementation. This thesis describes the design and implementation of Collection Tree Protocol over WirelessHART Data-Link layer. The implementation is done using TinyOS, nesC programming language using Crossbow TelosB CC2420 radio chip nodes. The results and experiments show the evaluation of the system prototype.

Стилі APA, Harvard, Vancouver, ISO та ін.

38

Nedstrand, Paul, and Razmus Lindgren. "Test Data Post-Processing and Analysis of Link Adaptation." Thesis, Linköpings universitet, Institutionen för datavetenskap, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-121589.

Повний текст джерела

Анотація:

Analysing the performance of cell phones and other wireless connected devices to mobile networks are key when validating if the standard of the system is achieved. This justies having testing tools that can produce a good overview of the data between base stations and cell phones to see the performance of the cell phone. This master thesis involves developing a tool that produces graphs with statistics from the trac data in the communication link between a connected mobile device and a base station. The statistics will be the correlation between two parameters in the trac data in the channel (e.g. throughput over the channel condition). The tool is oriented on analysis of link adaptation and by the produced graphs the testing personnel at Ericsson will be able to analyse the performance of one or several mobile equipments. We performed our own analysis on link adaptation using the tool to show that this type of analysis is possible with this tool. To show that the tool is useful for Ericsson we let test personnel answer a survey on the usability and user friendliness of it.

Стилі APA, Harvard, Vancouver, ISO та ін.

39

Abrishami, Mahdi. "Dynamic Link Flow Estimation according to Historical Travel Times." Thesis, Linköpings universitet, Kommunikations- och transportsystem, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-144583.

Повний текст джерела

Анотація:

Vast application of ITS and the availability of numerous on-road detection devices has resulted in variety of alternative data sources to be exploited and used in the field of traffic modelling. In this thesis, historical travel times, as an alternative data source, is employed on the developed method to perform dynamic network loading. The developed method, referred to as DNLTT, uses the share of each route available in the route choice set from the initial demand, as well as link travel times to perform the network loading. The output of the algorithm is time-dependent link flows. DNLTT is applied on Stockholm transportation network, where it is expected to have variation in link travel times in different time-periods, due to network congestion. In order to calculate the route shares, a time-sliced OD matrix is used. The historical travel times and the routes in the route choice set are extracted from an existing route planning tool. An available logit model, which considers the route travel time as the only logit parameter, is used for the route share calculation and the network loading is performed according to 2 different methods of DNLTT and DL. The evaluation of results is done for a toy network, where there happen different network states in different time-periods. Furthermore, the model output from Stockholm case study is analyzed and evaluated. The dynamic behavior of DNLTT is studied by analysis of link flows in different time-periods. Furthermore, the resulting link flows from both network loading methods are compared against observed link flows from radar sensors and the statistical analysis of link flows is performed accordingly. DNLTT exhibits a better performance on the toy network compared to DL, where the increasing link travel times cause the link flows to decline in different time-periods. However, the output of the developed method does not resemble the observed link flows for the investigated links in Stockholm case study. It is strongly believed, that the performance of DNLTT on the investigated transportation network potentially improves, in case the historical travel times better resemble the network dynamics. In addition to a more reliable data set, an OD adjustment process in all the time-periods is believed to generate better model output.

Стилі APA, Harvard, Vancouver, ISO та ін.

40

Wernberg, Max. "Security and Privacy of Controller Pilot Data Link Communication." Thesis, Linköpings universitet, Kommunikations- och transportsystem, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-156337.

Повний текст джерела

Анотація:

Newly implemented technologies within the aviation lack, according to recent studies, built in security measures to protect them against outside interference. In this thesis we study the security and privacy status of the digital wireless Controller Pilot Data Link Communication (CPDLC) used in air traffic management alongside other systems to increase the safety and traffic capacity of controlled airspaces. The findings show that CPDCL is currently insecure and exposed to attacks. Any solutions to remedy this must adhere to its low levels of performance. Elliptical Curve Cryptography, Protected ACARS and Host Identity Protocol have been identified as valid solutions to the systems security drawbacks and all three are possible to implement in the present state of CPDLC.

Стилі APA, Harvard, Vancouver, ISO та ін.

41

Makridis, Evagoras. "Reinforcement Learning for Link Adaptation in 5G-NR Networks." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-290081.

Повний текст джерела

Анотація:

The Adaptive Modulation and Coding (AMC) scheme in the link adaptation is a core feature in the current cellular networks. In particular, based on Channel Quality Indicator (CQI) measurements that are computed from the Signal-to-Interference-plus-Noise Ratio (SINR) level of User Equipment (UE), the base station (e.g., Next Generation NodeB (gNB)) selects a Modulation and Coding Scheme (MCS) to be used for the next downlink transmission. However, communication channels are inherently variant due to changes in traffic load, user mobility, and transmission delays and thus the estimation of the SINR levels at the transmitter side usually deviates from the actual value. The Outer-Loop Link Adaptation (OLLA) technique was proposed to improve the channel quality estimation by adjusting the value of SINR by an offset dependent on whether previous transmissions were decoded successfully or not captured by Hybrid Automatic Repeat Request (HARQ) feedback. Although this technique indeed improves the user throughput, it typically takes several Transmission Time Intervals (TTIs) to converge to a certain SINR value that fulfills a predefined target Block Error Rate (BLER). As a result, the slow convergence speed of the OLLA mechanism causes inaccurate MCS selection specially for users with bursty traffic, while it needs to be a priori tuned with a fixed BLER target. These factors lead to degraded network performance, in terms of throughput and spectral efficiency. To cope with these challenges, in this project we propose a reinforcement learning (RL) framework where an agent takes observations from the environment (e.g., from UEs and the network) and learns proper policies that adjust the estimated SINR, such that a reward function (i.e., the UE normalized throughput) is maximized. This framework was designed and developed in a radio network system-level simulator, while for the agents using RL (hereafter called RL agents), Deep Q-Network (DQN) and Proximal Policy Optimization (PPO) models were trained accordingly. Both models showed significant increment of about 1.6% - 2.5% and 10% - 17% on the average throughput for mid-cell and cell-edge users respectively, over the current state-of-the-art OLLA mechanism. Finally, setting a priori a fixed BLER target is not needed, and hence the RL-based link adaptation performs well in diverse radio conditions.
Adaptive Modulation and Coding (AMC)-schemat i länkanpassning är en central funktion i nutida mobilnätverk. Baserat på Channel Quality Indicator (CQI)-mätningar som är beräknade från Signal-till-Störning-plus- Brusförhållande (SINR)-nivån av User Equipment (UE), väljer basstationen (t.ex., Next Generation NodeB (gNB)) ett Modulerings och kodningsschema (MKS) som används till nästa nedlänksöverföring. Kommunikationskanaler uppvisar dock variationer av sig själva på grund av förändringar i trafikbelastning, användarmobilitet, och överföringsfördröjningar. Detta gör att uppskattningen av SINR-nivåer i sändarsidan avviker från det faktiska värdet. Outer-Loop Link Adaptation (OLLA)-metoden föreslogs för att förbättra uppskattningen av kanalkvaliteten genom att justera värdet på SINR med en förskjutning beroende på om tidigare sändningar avkodades framgångsrikt eller alternativt om de inte fångades av återkoppling från Hybrid Automatic Repeat Request (HARQ). Även om denna teknik förbättrar användares genomströmning, tar det vanligtvis flera sändningstidsintervall (TTI) för att konvergera till ett visst SINR-värde som uppfyller en fördefinierad målfelsfrekvens (BLER). Som ett resultat orsakar OLLA-mekanismens långsamma konvergenshastighet ett felaktigt MCS-val, speciellt för användare med tuff trafik. OLLA-mekanismen måste även anpassas efter ett fast BLER-mål. Dessa faktorer leder till försämrad nätverksprestanda när det gäller genomströmning och spektral effektivitet. För att klara av dessa utmaningar föreslår vi i detta projekt en förstärkningsinlärningsram (RL) där en agent tar observationer från miljön (t.ex. från UE:er och nätverket) och lär sig riktiga policies som justerar den uppskattade SINR:en, så att en belöningsfunktion (dvs. UEnormaliserad genomströmning) maximeras. Denna ram utformades och utvecklades i en radiosimulator på systemnivå. För de agenter som använde RL (hädanefter RL-agenter) utbildades Deep Q-Network (DQN) och Proximal Policy Optimization (PPO)-modeller på lämpligt sätt. Båda modellerna visade en signifikant ökning på cirka 1,6% - 2,5% och 10% - 17% av den genomsnittliga genomströmningen för mellancellsanvändare respektive cellkantsanvändare, jämfört med den nuvarande toppmoderna OLLA mekanismen. Slutligen är det inte nödvändigt att apriori sätta ett fast BLER-mål, och därför fungerar den RL-baserade länkanpassningen bra under olika radioförhållanden.

Стилі APA, Harvard, Vancouver, ISO та ін.

42

Fredmer, Andreas. "Inter-Satellite Link Design for Nanosatellites in New Space." Thesis, Luleå tekniska universitet, Rymdteknik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-81082.

Повний текст джерела

Анотація:

New Space is a phrase used to describe the expanding commercialization into the areas of space, for instance the Low Earth Orbit at approximately 500 km altitude. This is due to the decrease in cost as the satellites are becoming smaller and the transport vehicles cheaper. This reduction of cost provide the opportunity for industry and researchers tosend up customized equipment to orbit with standardized smaller satellites, such as the nanosatellites. Many parts of the nanosatellites system are commercially available but some subsystems are dependent on the situation. One of which is the satellite to satellite communication, referred to as Inter-Satellite Link (ISL). This thesis aims To evaluate the feasibility of asystem that allow for ISL capability and the basic operations of a satellite. Two hypothetical mission designs, Earth Observation and Global Coverage, were used to simulate the restrictions and requirements of the subsystems together with Commercial Of the Shelf (COTS) equipment to consider the satellite system as a whole. The major principles of the Radio Frequency (RF) communication system and their low level components are investigated and discussed. The scope of this thesis were to present and evaluate the high system level of the satellite. Thus the results and discussion describe a theoretical system performance that could be achieved with suggestions of low level components and system conﬁguration. Besides from the communication subsystem this thesis also includes theory of mission design, the satellite subsystems and external interactions to describe how it all aﬀects the design work of the communication system. Conclusion of this work oﬀers a versatile preliminary system design that is theoretically capable of limited ISL communications. Furthermore this thesis include the fundamental principles of the satellite system that can be used for further work or alternative mission designs.

Стилі APA, Harvard, Vancouver, ISO та ін.

43

Tiainen, Arttu. "Inter-Satellite Link Antennas : Review and The Near Future." Thesis, Luleå tekniska universitet, Rymdteknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-62541.

Повний текст джерела

Анотація:

The emerging trend in distributed spacecraft systems of using multiple spacecraft which share functions as opposed to independent spacecraft has given opportunities for missions previously infeasible. Inter-satellite link (ISL) communications provide a direct link within the space segment without need of an intermediate ground segment to relay the data. As the distributed spacecraft systems (DSS) have become less exotic and more complex, the need and demand for inter-satellite antenna systems has increased and the requirements for the antenna systems more diverse and become more demanding. This document is a research of the antennas currently used for ISL, already flown or will be launched in the near future. While the emphasis is strongly in the antennas, the other parts of the ISL communications sub-systems are observed. To limit the scope of the work, optical cross links are not observed in this document. ISL used only for very close proximity, such as several kilometres, are given only limited scope as the main challenges on those do not involve antennas. Furthermore, the major emphasis is given to systems which can be seen as commercially important. This document is divided in five main sections and the conclusions. In the first section the features and the challenges of ISLs are described. In the second section a parametrisation system for antennas is defined and this system is used in following sections to describe the ISL sub-systems and antenna used in them. The third part is a survey of recently flown space missions with ISLs. The fourth section is a survey on the missions which are scheduled to fly in near future and a brief survey of the solutions offered by satellite service providers and manufacturers. Due to the limited technical data available, the fourth section contains far more reverse engineering and assumptions than the survey on legacy missions. The fifth section describes the several families of ISL suitable antennas under development and discusses about several topics which relate to the ISL antenna development. In this part also are defined several example antenna specifications and the applications of those. The study concludes that antennas suitable for inter-satellite links are not inherently different from ground segment communication antennas of the S/C. The major difference is the need for greater coverage, which can be attained by multiple antenna elements, beam steering or antenna pointing. Specific considerations are needed to be taken into account and often the use of ISLs will increase the technical challenges, but it can provide solutions for problems which cannot be solved otherwise.
çDie sich abzeichnende Entwicklung von Einzelsatellitensysteme hin zu Systemen mit einer Vielzahl an Plattformen gleicher Funktionalität, eröffnet Möglichkeiten für die Durchführung von Missionen die bisher als nicht praktikabel/undurchführbar bewertet wurden. Inter-satellite Link (ISL) Kommunikation stellt eine direkte Verbindung zwischen den einzelnen Komponenten eines Raumsegments zur Verfügung ohne auf ein zwischengeschaltetes Bodensegment zur Datenübertragung angewiesen zu sein. Die gestiegene Anwendungshäufigkeit und Komplexität von Distributed Spacecraft Systemen (DSS) bringen eine Erhöhung der Nachfrage bezüglich Antennen für die inter-satelliten Kommunikation mit sich, wobei die Anforderungen an diese vielfältiger und anspruchsvoller geworden sind. Diese Abschlussarbeit stellt eine Untersuchung bezüglich Antennensystemen dar, welche in der Vergangenheit, der Gegenwart sowie der nahen Zukunft ihre Verwendung in der ISL fanden und finden werden. Während auch die anderen Bestandteile eines ISL Kommunikation Subsystems betrachtet werden, liegt der Schwerpunkt der Studie maßgeblich auf den Antennen selbst. Um den Rahmen der Arbeit zu wahren wird auf die Betrachtung optischer Kommunikationssysteme verzichtet. Bei inter-satellite Link Systemen die zur Datenübertragung über kurze Distanzen von nur einigen Kilometern benutzt werden liegen die Herausforderungen nicht bei den Antennen, weswegen diese nur bedingt untersucht werden. Weiter werden besonders die Systeme betrachtet welche als wichtig für die kommerzielle Anwendung erachtet werden können. Diese Arbeit ist in insgesamt sechs Abschnitte unterteilt. Im ersten Kapitel werden zunächst die Eigenschaften und die Herausforderungen bezüglich ISLs erläutert. Ein System zur Parametrisierung von Antennen wird im zweiten Kapitel definiert um es in den folgenden Abschnitten zur Beschreibung der ISL Subsysteme anzuwenden. Eine Analyse der Instrumentierung vergangener Weltraummission mit ISL Systemen wird im dritten Kapitel durchgeführt, die Betrachtung zukünftiger Missionen erfolgt in Kapitel 4. Da für Letztere nur begrenzt technische Daten zur Verfügung stehen, beinhaltet das vierte Kapitel weitaus mehr Reverse Engineering und Annahmen als die Untersuchung abgeschlossener Missionen. Im fünften Kapitel werden verschiedenen, für die inter-satellite Kommunikation geeigneten Antennentypen beschrieben und unterschiedliche Themen bezüglich der ISL Antennenentwicklung diskutiert. Weiter werden in diesem Abschnitt verschiedene Antennenspezifikationen definiert und entsprechende Anwendungsbeispiele beschrieben. Im letzten Teil werden die gefundenen Erkenntnisse abschließend diskutiert. Die Untersuchung zeigt dass Antennen welche für die inter-satelliten Kommunikation geeignet sind, sich grundsätzlich nicht von gängigen Antennen zur Bodensegmentkommunikation des S/C unterscheiden. Der Hauptunterschied liegt in der Notwendigkeit einer größeren Abdeckung. Dies kann durch eine größere Anzahl von Antennenelementen, Strahlsteuerung oder Antennenausrichtung erreicht werden. Systemspezifische Erwägungen müssen in Betracht gezogen werden wobei die Anwendung von ISL Systemen die technischen Herausforderungen/Anforderungen erhöht. Im Gegenzug ermöglicht sie Lösungen für Probleme die auf andere Weise nicht behandelt werden können.
Une nouvelle tendance est apparue dans les systèmes décentralisés des satellites, consistant à utiliser plusieurs satellites qui partagent des fonctionnalités, plutôt que des satellites indépendants. Cela a rendu possible des missions qui étaient précédemment irréalisables. Le lien inter-satellite (ISL) permet en effet de communiquer directement dans l’espace, sans devoir utiliser le segment sol pour transmettre les données. Alors que les systèmes décentralisés des satellites (DSS) sont devenus moins exotiques et plus complexes, la nécessité et la demande de systèmes d’antennes inter-satellite se sont développées et les exigences pour les systèmes d’antennes se sont diversifiés et sont devenus plus contraignants. Ce document réalise une étude des différentes antennes actuellement utilisées pour le ISL, dont certaines sont déjà opérationnelles et d’autres seront lancées prochainement. Tandis qu’il met fortement l’accent sur les antennes en ellesmêmes, il étudie aussi les autres parties des sous-systèmes de communication ISL. Néanmoins, pour limiter la portée du document, les réticulations optiques ne sont pas abordées. De même, les ISLs utilisés pour les communications à faible portée, de l’ordre de quelques kilomètres, ne sont que brièvement évoquées, étant donné que les défis majeurs concernant ceux-ci n’impliquent pas les antennes. Au delà de ça, ce document met surtout l’accent sur les systèmes qui peuvent être vu comme commercialement importants. Ce document est divisé en cinq sections, en plus de la conclusion. Dans la première section sont décrit les caractéristiques et les challenges des ISLs. Dans la seconde section, un système de paramétrage pour les antennes est défini et ce système est utilisé dans les sections suivantes pour décrire les sous-systèmes ISLs ainsi que les antennes associées. La troisième partie donne un aperçu des récentes missions spatiales lancées avec ISLs. La quatrième section étudie quant à elle les missions prochainement programmées et donne un bref aperçu des solutions offertes par les fournisseurs et fabricants des services satellitaires. Dû à la limitation des donéees techniques disponibles, cette section est principalement basée sur l’ingénierie inverse et des hypothèses, comparé aux missions déjà lancées et discutées en section 3. Finalement, la cinquième section décrit les différentes familles d’antennes ISL sous développement et discute de plusieurs sujets liés à leur développement. Elle définit aussi plusieurs exemples de spécifications d’antennes, et les applications associées. L’étude conclut que les antennes adaptées pour les liens inter-satellite ne sont pas très différentes des antennes de communication au sol du satellite, la plus grande différence étant la nécessité d’une plus grande couverture réseau. Celle-ci peut être atteinte via l’utilisation de plusieurs antennes, l’orientation du faisceau ou le pointage de l’antenne. Des considérations particulières doivent être prises en compte et souvent, l’utilisation des ISLs augmente les défis techniques. Néanmoins, cela constitue une solution à des problèmes qui ne peuvent pas être résolus autrement.

Стилі APA, Harvard, Vancouver, ISO та ін.

44

Frykskog, David, and Hjalmar Jonsson. "Construction of RF-link budget template for transceiver modelling." Thesis, Linköpings universitet, Fysik och elektroteknik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-162159.

Повний текст джерела

Анотація:

This master thesis report details the process of developing a simulation platform for radio transceivers with a focus on analog receiver front end system design. The platform was implemented in the National Instruments VSS environment for the company Ericsson AB.

Стилі APA, Harvard, Vancouver, ISO та ін.

45

Tamoor-ul-Hassan, Syed, and Serkan Demir. "Fast Packet Retransmissions in LTE." Thesis, Linköpings universitet, Kommunikationssystem, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-72166.

Повний текст джерела

Анотація:

The cellular networks are evolving to meet the future requirements of data rate,coverage and capacity. The fourth generation mobile communication system, LTEhas been developed to meet these goals. LTE uses multiple antenna features andlarger bandwidths in order to accomplish this task. These features will furtherextend the requirements of data rate, coverage, latency and flexibility. LTE also utilizes the varying quality of the radio channel and the interferencefrom other transmitters by adapting the data rate to the instantaneous channelquality at all the time. This is typically referred to as Link Adaptation. Thelink adaptation fails from time to time due to the varying channel quality as wellas the interference from other transmitters. In order to counteract these failures,retransmission methods are employed. These methods detect the errors on thereceiver side and signals the transmitter for the retransmission of the erroneousdata. The efficiency of link adaptation increases if combined with a properly designedretransmission scheme at the expense of delays due to retransmissions. This master thesis focuses on the study of the retransmission schemes with fasterfeedback, resulting in a reduction in delay. The feedback is generated by makingan early estimate of the decoding outcome and sending it early to the transmitterresulting in faster retransmission. This is important in certain applications wherethe data transmission is intolerant to delays.The thesis work shows by system performance simulations that fast packet retransmission,precisely called Early HARQ Feedback, significantly affects the systemperformance together with the utilization of the link adaptation. The study alsoshows that the link adaptation, in certain scenarios, can be optimized to improvethe system performance. In that respect, it is also possible to increase the numberof retransmissions within the same resource utilization. That optimization is basicallycalled aggressive link adaptation. Consequently, Early HARQ Feedback incombination with aggressive link adaptation provides a large improvement in thedownlink performance of the studied cases.

Стилі APA, Harvard, Vancouver, ISO та ін.

46

Mroczkowski, Maciej. "Projective links and their invariants /." Uppsala : Matematiska institutionen, Univ. [distributör], 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-4519.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

47

Shabbir, Noman, and Hasnain Kasif. "Radio Resource Management in WiMAX." Thesis, Blekinge Tekniska Högskola, Avdelningen för signalbehandling, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-1227.

Повний текст джерела

Анотація:

Today, different types of cellular networks are actively working on the radio links. For instance, the Global System for Mobile Communication (GSM) is being used in nearly two hundred countries and currently it has around two and half billion users all over the world. Universal Mobile Telecommunication System (UMTS) is currently deployed in many countries and it is providing increased data rates, coverage and mobility as compared to GSM. Wireless Local Area Networks (WLAN) are very famous when we have a small area and none real time services. Worldwide Interoperability for Microwave Access (WiMAX) is a new technology and it is in deployment phase. In all these cellular technologies, we have very limited recourses and we have to make best use of them by proper management. Radio Resource Management (RRM) is a control mechanism for the overall system which is being used to manage radio resources in the air interface inside a cellular network. The main objective is to utilize the available spectral resources as efficiently as possible. Our aim is to use them in the best possible way to maximize the performance and spectral efficiency in such a way that we have maximum number of users in our network and Quality of Service (QoS) is up to the mark. In a cellular communication system, a service area or a geographical region is divided into a number of cells and each cell is served by an infrastructure element called the base station which works through a radio interface. The frequency license fees, real estate, distribution network and maintenance are the issues which dominates the cost for deploying a cellular network. Management of radio related resources is a critical design component in cellular communications. In RRM, we control parameters like Radio Frequency (RF) planning, link budgeting, modulation schemes, channel access schemes etc. RF planning includes cell planning, coverage of the network and capacity of the network. Our main focus in this thesis will be on cell planning and link budgeting and we will discuss them in context of a WiMAX network.

Стилі APA, Harvard, Vancouver, ISO та ін.

48

Ruberg, Anders. "Frequency Domain Link Adaptation for OFDM-based Cellular Packet Data." Thesis, Linköping University, Department of Electrical Engineering, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-6328.

Повний текст джерела

Анотація:

In order to be competitive with emerging mobile systems and to satisfy the ever growing request for higher data rates, the 3G consortium, 3rd Generation Partnership Project (3GPP), is currently developing concepts for a long term evolution (LTE) of the 3G standard. The LTE-concept at Ericsson is based on Orthogonal Frequency Division Multiplexing (OFDM) as downlink air interface. OFDM enables the use of frequency domain link adaptation to select the most appropriate transmission parameters according to current channel conditions, in order to maximize the throughput and maintain the delay at a desired level. The purpose of this thesis work is to study, implement and evaluate different link adaptation algorithms. The main focus is on modulation adaptation, where the differences in performance between time domain and frequency domain adaptation are investigated. The simulations made in this thesis are made with a simulator developed at Ericsson. Simulations show in general that the cell throughput is enhanced by an average of 3% when using frequency domain modulation adaptation. When using the implemented frequency domain power allocation algorithm, a gain of 23-36% in average is seen in the users 5th percentile throughput. It should be noted that the simulations use a realistic web traffic model, which makes the channel quality estimation (CQE) difficult. The CQE has great impact on the performance of frequency domain adaptation. Throughput improvements are expected when using an improved CQE or interference avoidance schemes. The gains with frequency domain adaptation shown in this thesis work may be too small to motivate the extra signalling overhead required. The complexity of the implemented frequency domain power allocation algorithm is also very high compared to the performance enhancement seen.

Стилі APA, Harvard, Vancouver, ISO та ін.

49

AAMIR, ZEESHAN. "Developing a Communication link between Agents and cross Platform IDE." Thesis, Högskolan Dalarna, Datateknik, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:du-4855.

Повний текст джерела

Анотація:

The main objective of this thesis work is to develop communication link between Runrev Revolution (IDE) and JADE (Multi-Agent System) through Socket programming using TCP/IP layer. These two independent platforms are connected using socket programming technique. Socket programming is considered to be newly emerging technology among these two platforms, the work done in this thesis work is considered to be a prototype.A Graphical simulation model is developed by salixphere (Company in Hedemora) to simulate logistic problems using Runrev Revolution (IDE). The simulation software/program is called “BIOSIM”. The logistic problems are complex, and conventional optimization techniques are unlikely very successful. “BIOSIM” can demonstrate the graphical representation of logistic problems depending upon the problem domains. As this simulation model is developed in revolution programming language (Transcript) which is dynamically typed and English-like language, it is quite slow compared to other high level programming languages. The object of this thesis work is to add intelligent behaviour in graphical objects and develop communication link between Runrev revolution (IDE) and JADE (Multi-Agent System) using TCP/IP layers.The test shows the intelligent behaviour in the graphical objects and successful communication between Runrev Revolution (IDE) and JADE (Multi-Agent System).

Стилі APA, Harvard, Vancouver, ISO та ін.

50

Stenström, Christer. "Link and effect model for performance improvement of railway infrastructure." Licentiate thesis, Luleå tekniska universitet, Drift, underhåll och akustik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-26417.

Повний текст джерела

Анотація:

Railway traffic has increased over the last decade and it is believed to increase further with transportation shifting from road to rail, due to rising energy costs and the demand to reduce emissions. To manage railway infrastructure assets effectively against agreed-upon and set objectives, performance must be measured and monitored. Different systems are used to collect and store data of traffic, failures, inspections, track quality, etc., for subsequent analysis and data exchange. Performance indicators (PIs), e.g. for RAMS (reliability, availability, maintainability, safety), are continuously developed to support infrastructure managers (IMs) in identifying performance killers in order to make efficient and effective decisions. However, they are often ad hoc and seldom standardised. Moreover, the use of standards and the need for harmonisation of railway operations have grown with interoperability, e.g. building of a trans-European railway network. The~efficiency and effectiveness of railway infrastructure can be improved if an appropriate performance measurement (PM) system is identified and specifically developed. In traditional PM systems, PIs are given threshold values, indicating when an action needs to be taken, i.e. they can to some extent be reactive. Also, PIs are often aggregated measures, which can make them abstract. By this trend in transportation and shortcomings in performance measurement, there is a need to improve the strategic planning and measurement of performance for more proactive decision making and future standardisation.In this research, a link and effect model for performance improvement of railway infrastructure is developed. It provides a continuous methodology for breaking down objectives into operational requirements and linking them to results, using performance indicators, and algorithms for data analysis and simulation, for decision support.Keywords: railway infrastructure, performance, RAMS, maintenance, dependability, indicators, link and effect, decision support
Godkänd; 2012; 20120820 (chrste); LICENTIATSEMINARIUM Examinator: Biträdande professor Aditya Parida, Institutionen för samhällsbyggnad och naturresurser, Luleå tekniska universitet Diskutant: Universitetslektor Antti Salonen, Mälardalens högskola Tid: Torsdag den 20 september 2012 kl 10.00 Plats: F1031, Luleå tekniska universitet
Link and Effect Model for Maintenance of Railway Infrastructure

Стилі APA, Harvard, Vancouver, ISO та ін.

Дисертації з теми "Link Resolver"

Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями