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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
61

Some Investigations on QoS in the Wireline-Wireless Network Interface Zone

Tewari, Maneesh 03 1900 (has links)
In the next generation of networks we will begin to see the true convergence of voice, multimedia, and data traffic. This merging of various dedicated networks will occur both in the wired and wireless domains. Given the growth in the areas of wireless voice and data, we see that the combination of mobile and Internet communication constitutes the driving force behind the third-generation wireless system and makes the basis for the fourth-generation wireless system. For services like voice over IP over wireless (VoIPoW), the main challenge is to achieve QoS and spectrum efficiency. In order to support better QoS the IETF Mobile IP Working Group is discussing a number of enhancements to the base protocol to reduce the latency, packet loss and signaling overhead experienced during handoff. This support also includes both the call admission and the subsequent scheduling of packet transmissions. In this thesis, we will first survey the work done on issues related to QoS provisioning for wireless network and then will address bandwidth allocation problem in packet radio network with special emphasis on wireline to wireless internetworking zone. The main aim of the thesis is to evolve a strategy to reduce the call dropping probability by negotiating the QoS in those conditions when we do not have the sufficient resources (mainly bandwidth) to allocate. In order to achieve the QoS we have investigated the behaviour of the Real-time Voice traffic on a wireless link and its relation to the associated quality of service. This investigation opens a way for QoS negotiation, in a condition like during handoff, when the network is not able to sustain the negotiated bandwidth. The main results of this work are, that even with reduced bandwidth, quality for speech can be maintained at a reasonable level and this way the call dropping can be reduced. Such a scheme is useful in those conditions when we do not have the sufficient bandwidth to allocate like during a handoff of a mobile host from one cell to another. Moreover the bandwidth is a scarce resource in wireless domain so there should be an efficient call admission control policy. Many call admission control policies are proposed in the literature; here we propose a simple scheme for real-time traffic, specially speech, in a base station which increases the system throughput. In addition to above, we have also experimented with Cellular IP, one of the implementations of proposed micro-mobility architecture to provide faster handoff and seamless mobility in wired and wireless network.
62

Global Localization of an Indoor Mobile Robot with a single Base Station

Hennig, Matthias, Kirmse, Henri, Janschek, Klaus 13 February 2012 (has links) (PDF)
The navigation tasks in advanced home robotic applications incorporating reliable revisiting strategies are dependent on very low cost but nevertheless rather accurate localization systems. In this paper a localization system based on the principle of trilateration is described. The proposed system uses only a single small base station, but achieves accuracies comparable to systems using spread beacons and it performs sufficiently for map building. Thus it is a standalone system and needs no odometry or other auxiliary sensors. Furthermore a new approach for the problem of the reliably detection of areas without direct line of sight is presented. The described system is very low cost and it is designed for use in indoor service robotics. The paper gives an overview on the system concept and special design solutions and proves the possible performances with experimental results.
63

Energy efficient cloud computing based radio access networks in 5G : design and evaluation of an energy aware 5G cloud radio access networks framework using base station sleeping, cloud computing based workload consolidation and mobile edge computing

Sigwele, Tshiamo January 2017 (has links)
Fifth Generation (5G) cellular networks will experience a thousand-fold increase in data traffic with over 100 billion connected devices by 2020. In order to support this skyrocketing traffic demand, smaller base stations (BSs) are deployed to increase capacity. However, more BSs increase energy consumption which contributes to operational expenditure (OPEX) and CO2 emissions. Also, an introduction of a plethora of 5G applications running in the mobile devices cause a significant amount of energy consumption in the mobile devices. This thesis presents a novel framework for energy efficiency in 5G cloud radio access networks (C-RAN) by leveraging cloud computing technology. Energy efficiency is achieved in three ways; (i) at the radio side of H-C-RAN (Heterogeneous C-RAN), a dynamic BS switching off algorithm is proposed to minimise energy consumption while maintaining Quality of Service (QoS), (ii) in the BS cloud, baseband workload consolidation schemes are proposed based on simulated annealing and genetic algorithms to minimise energy consumption in the cloud, where also advanced fuzzy based admission control with pre-emption is implemented to improve QoS and resource utilisation (iii) at the mobile device side, Mobile Edge Computing (MEC) is used where computer intensive tasks from the mobile device are executed in the MEC server in the cloud. The simulation results show that the proposed framework effectively reduced energy consumption by up to 48% within RAN and 57% in the mobile devices, and improved network energy efficiency by a factor of 10, network throughput by a factor of 2.7 and resource utilisation by 54% while maintaining QoS.
64

Análise dos condicionantes para licenciamento das estações radiobase de telefonia celular no município de Salvador-Ba

Silva, Denize Francisca da January 2009 (has links)
196f. / Submitted by Suelen Reis (suziy.ellen@gmail.com) on 2013-04-10T17:24:12Z No. of bitstreams: 1 Disser Denize Silva.pdf: 10999494 bytes, checksum: 148c85bcd29a326b717b5cf519d96f68 (MD5) / Approved for entry into archive by Rodrigo Meirelles(rodrigomei@ufba.br) on 2013-04-22T19:25:07Z (GMT) No. of bitstreams: 1 Disser Denize Silva.pdf: 10999494 bytes, checksum: 148c85bcd29a326b717b5cf519d96f68 (MD5) / Made available in DSpace on 2013-04-22T19:25:07Z (GMT). No. of bitstreams: 1 Disser Denize Silva.pdf: 10999494 bytes, checksum: 148c85bcd29a326b717b5cf519d96f68 (MD5) Previous issue date: 2009 / As estações radiobase de telefonia celular têm sido estudadas quanto aos potenciais impactos à saúde ambiental. Esta dissertação tem como objetivo, analisar os condicionantes para licenciamentos de estações radiobase de telefonia celular. Para atingir este objetivo, analisou-se as condicionantes para licenciamento de estações radiobase de telefonia celular no município de Salvador, comparando-os a quatro municípios brasileiros de grande porte e ao Distrito Federal, bem como a análise da percepção dos atores que, direta ou indiretamente, se relacionam com o tema em estudo e participam do processo de licenciamento das ERBs. Utilizou-se como estratégias metodológicas,a pesquisa qualitativa em duas etapas. Na primeira, a pesquisa documental e na segunda etapa a pesquisa de campo realizada por meio de entrevista semi-estruturada, para analisar a percepção de profissionais, representantes de órgãos, operadoras e da população que reside e/ou trabalha até 400m da ERB. A legislação analisada mostrou fragilidades. Destacam-se ausências de condicionantes como audiência pública e limites restritivos para densidade de potência e distanciamento.A pesquisa realizada em campo indicou que a maioria da população entrevistada acredita ter sido prejudicada com a instalação das ERBs de telefonia celular próxima às suas residências. Dessa forma, os resultados levam ao entendimento de que há necessidade de se adotar condicionantes mais restritivos para o licenciamento de estações radiobase, de modo a contemplar o princípio da precaução. / Salvador
65

Modernización de la red de acceso de un operador móvil para el caso de Lima Metropolitana

Otárola Correa, Diego Antonio, Campos Gonzales, Frank January 2015 (has links)
La presente tesina titulada “Modernización de la red de acceso de un operador móvil para el caso de Lima Metropolitana” expone una propuesta para un operador que tiene como objetivo poder incrementar su cobertura de servicio de segunda y cuarta generación, para esto se definen conceptos teóricos en base a lo que son las tecnologías de telefonía móvil celular de tipo GSM, UMTS y LTE y se compararan con las características técnicas de los equipos que se plantean usar demostrándose que estos pueden optimizar la red de acceso del operador en cobertura y funcionamiento para brindar un mejor servicio en base a 2G y 4G. Para lograr el objetivo propuesto, esta tesina describe el diseño y dimensionamiento de proyecto, pasos para su ejecución, especificaciones técnicas de los equipos, procedimiento para la puesta en servicio y resultados en base a pruebas del servicio y KPI. The current thesis entitled “Modernización de la red de acceso de un operador móvil para el caso de Lima Metropolitana” exposes a proposal for a mobile operator that has as a target increase their second and fourth generator coverage. For achieve this we have to defined theoric concepts based on the mobile telecommunication technology GSM, UMTS and LTE and compare with the features of equipment proposed to use proving that the coverage and performance of the access network of the operator can be improved for provide a better 2G and 4G service. For achieve this target proposed, this thesis describes the design and sizing of Project, steps for execution, technical features of equipment, on air procedure and results base on the testing service and KPI.
66

Learning-based methods for resource allocation and interference management in energy-efficient small cell networks

Samarakoon, S. (Sumudu) 07 November 2017 (has links)
Abstract Resource allocation and interference management in wireless small cell networks have been areas of key research interest in the past few years. Although a large number of research studies have been carried out, the needs for high capacity, reliability, and energy efficiency in the emerging fifth-generation (5G) networks warrants the development of methodologies focusing on ultra-dense and self-organizing small cell network (SCN) scenarios. In this regard, the prime motivation of this thesis is to propose an array of distributed methodologies to solve the problem of joint resource allocation and interference management in SCNs pertaining to different network architectures. The present dissertation proposes and investigates distributed control mechanisms for wireless SCNs mainly in three cases: a backhaul-aware interference management mechanism of the uplink of wireless SCNs, a dynamic cluster-based approach for maximizing the energy efficiency of dense wireless SCNs, and a joint power control and user scheduling mechanism for optimizing energy efficiency in ultra-dense SCNs. Optimizing SCNs, especially in the ultra-dense regime, is extremely challenging due to the severe coupling in interference and the dynamics of both queues and channel states. Moreover, due to the lack of inter-base station/cluster communications, smart distributed learning mechanisms are required to autonomously choose optimal transmission strategies based on local information. To overcome these challenges, an array of distributed algorithms are developed by combining the tools from machine learning, Lyapunov optimization and mean-field theory. For each of the above proposals, extensive sets of simulations have been carried out to validate the performance of the proposed methods compared to conventional models that fail to account for the limitations due to network scale, dynamics of queue and channel states, backhaul heterogeneity and capacity constraints, and the lack of coordination between network elements. The results of the proposed methods yield significant gains of the proposed methods in terms of energy savings, rate improvements, and delay reductions compared to the conventional models studied in the existing literature. / Tiivistelmä Langattomien piensoluverkkojen resurssien allokointi ja häiriön hallinta on ollut viime vuosina tärkeä tutkimuskohde. Tutkimuksia on tehty paljon, mutta uudet viidennen sukupolven (5G) verkot vaativat suurta kapasiteettia, luotettavuutta ja energiatehokkuutta. Sen vuoksi on kehitettävä menetelmiä, jotka keskittyy ultratiheisiin ja itseorganisoituviin piensoluverkkoihin. (SCN). Tämän väitöskirjan tärkein tavoite onkin esittää joukko hajautettuja menetelmiä piensoluverkkojen yhteisten resurssien allokointiin ja häiriön hallintaan, kun käytössä on erilaisia verkkoarkkitehtuureja. Tässä väitöskirjassa ehdotetaan ja tutkitaan hajautettuja menetelmiä langattomien piensoluverkkojen hallintaan kolmessa eri tilanteessa: välityskanavan huomioiva häiriönhallinta menetelmä langattomissa piensoluverkoissa, dynaamisiin klustereihin perustuva malli tiheiden langattomien piensoluverkkojen energiatehokkuuden maksimointiin ja yhteinen tehonsäädön ja käyttäjien allokaatio menetelmä ultratiheiden piensoluverkkojen energiatehokkuuden optimointiin. Ultratiheiden piensoluverkkojen optimointi on erittäin haastavaa häiriön sekä jonojen ja kanavatilojen vahvojen kytkösten vuoksi. Lisäksi, koska klustereilla/tukiasemilla ei ole kommunikaatiota, tarvitaan hajautettuja oppimisalgoritmeja, jotta saadaan itsenäisesti valittua optimaaliset lähetys menetelmät hyödyntäen vain paikallista tietoa. Tämän vuoksi kehitetään useita hajautettuja algoritmeja, jotka hyödyntävät koneoppimista, Lyapunov optimointia ja mean-field teoriaa. Kaikki yllä olevat esitetyt menetelmät on validoitu laajoilla simulaatioilla, joilla on voitu todentaa niiden suorituskyky perinteisiin malleihin verrattuna. Perinteiset mallit eivät pysty ottamaan huomioon verkon laajuuden, jonon ja kanavatilojen dynamiikan, eri välityskanavien ja rajallisen kapasiteetin asettamia rajoituksia sekä verkon elementtien välisen koordinoinnin puuttumista. Esitetyt menetelmät tuottavat huomattavia parannuksia energiansäästöön, siirtonopeuteen ja viiveiden vähentämiseen verrattuna perinteisiin malleihin, joita kirjallisuudessa on tarkasteltu.
67

Datová fúze satelitní navigace a kompasu / Sattelite Navigation and Compasss Data Fusion

Maceček, Ivo January 2010 (has links)
Theoretical information about different satellite navigation systems used for determination of position. Special attention is attended to system GPS. There are consulted main principles of the GPS and some error sources. Application of differential GPS for minimization of these errors is discussed. Next part is about examples of basic principles for measuring earth magnetic field. Last chaps are about practical realization of mentioned DGPS, which is applied for outdoor mobile robot navigation. There is described hardware structure, software utilities and application of an aided tool for GPS - electronic compass. Some practical measurements and results are presented.
68

Senzorický systém robotu Minidarpa / Minidarpa robot - senzoric subsystem

Sedlák, Luboš January 2010 (has links)
This master’s thesis describes a sensorial subsystem of a mobile robot. The thesis mentions the structure and a basis of the satellite navigation. There are also described each systems and visualization techniques as e. g. WGS 84, including also other systems for specification of more accurate position on the Earth (EGNOS, WAAS and others). This thesis describes closely also a differential GPS and the corrections. For the purposes of the thesis there has been assembled GPS software for a fundamental and a remote station. There have been chosen and used modules for receiving a GPS signal and wireless modules for their communication. There are also used outcomes from the project of the Open Street Map in the thesis. Results of this project are described in details, decoded, adjusted and converted into RNDF file. At the end of this thesis there has been composed a function of the program for portable camera which works on principle time of flight. This portable camera is dedicated to look for immediate barrier and also for 3D space view in front of the robot. This thesis also including the process how the power source has been built up for this portable scanner.
69

Providing accurate time information to a radio base station via a GPS receiver emulator

Khorami, Elham January 2013 (has links)
In recent years, there has been a significant increase in the use of Global Positioning Satellite system (GPS) technology, consequently the usage of GPS receivers has increased. These GPS receivers can be used as a synchronization source for radio base stations by generating precise 1 pulse per second signals and providing National Marine Electronics Association (NMEA) data. The prototype developed in this thesis, implements a GPS receiver emulator to emulate a GPS receiver which is to be used for radio base station synchronization. Hardware and software have been used to generate the NMEA messages and to generate a precise 1 pulse per second signal. A graphical user interface (GUI) has been created in order to allow the operators of the emulator to input various parameters to the system used to emulate a GPS receiver. Using this emulator avoids the need for expensive GPS receivers and their connection to an antenna with a good view of the GPS satellites. More importantly, this GPS receiver emulator makes it easier to set up a lab environment for testing different situations with regard to signaling with NMEA data between the emulated GPS receiver and the radio base station equipment that is under test. For example, this allows tests involving incorrect NEMA messages or non once per second pulses. / De senaste åren har det skett en significant ökning av användandet av GPS teknik; följdaktligen har användandet av GPS mottagare ökat. GPS mottagare kan användas som en synkroniseringskälla för radiobasstationer genom att generera exakt 1 puls per sekund och därmed förse NMEA datan. Prototypen som utvecklats i detta examensarbete, implementerar en GPS emulator för att erbjuda en effektiv lösning till att emulera en GPS mottagare som används för synkronisering av basstationer. Olika hårdvara och mjukvara har använts för att simulera NMEA meddelanden och för att generera en precis 1 puls per sekund signal. Ett grafiskt gränssnitt (GUI) har utvecklats för att tillåta användaren av emulatorn att mata in olika parametrar till systemet som används för att emulera GPS mottagaren. Användandet av den här emulatorn tar bort behovet av dyra GPS mottagare, och gör det enklare att sätta upp en labbmiljö för testandet av olika situationer med hänsyn till signalering mellan 1 puls per sekund och NMEA datan av den simulerade GPS mottagaren och basstationshårdvaran som testas.
70

Modelling and analysis of dynamic spectrum sharing in cognitive radio based wireless regional area networks :|bmodelling and performance evaluation of initialization and network association of customer premise equipments with the base station in cognitive radio based IEEE 802.22 wireless regional area networks.

Afzal, Humaira January 2014 (has links)
The development of the IEEE 802.22 standard is aimed at providing broadband access in rural areas by effectively utilizing the unused TV band, provided no harmful interference is caused to the incumbent operation. This thesis presents the analytical framework to evaluate the number of active customer premise equipments (CPEs) in a wireless regional area network. Initial ranging is the primary process in IEEE 802.22 networks for CPEs to access the network and establish their connections with the base station (BS). A comprehensive analysis of initial ranging mechanism is provided in this work and initial ranging request success probability is derived based on the number of contended CPEs and the initial contention window size. Further, the average ranging success delay is derived for the maximum backoff stages. The collision probability is highly dependent on the size of the initial contention window and the number of contended CPEs. To keep it at a specific level, it is necessary for the BS to schedule the required size of the initial contention window to facilitate the maximum number of CPEs to establish their connections with reasonable delay. Therefore, the optimized initial window size is proposed that meets the collision probability constraint for a particular number of contended CPEs. An analytical model is also developed to estimate the ranging request collision probability depending upon the size of initial contention window and the number of contended CPEs. Moreover, this approximation provides the threshold size for contention window to start the initial ranging process in the IEEE 802.22 network. / Bahauddin Zakariya University Multan, Pakistan.

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