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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Uma análise da QoS na transmissão em redes 802.11G sob presença de interferência Bluetooth

FIGUEIREDO, Leandro Cabral 31 January 2008 (has links)
Made available in DSpace on 2014-06-12T17:37:52Z (GMT). No. of bitstreams: 2 arquivo5362_1.pdf: 5616622 bytes, checksum: fbebee21a2ff84ffecc9790e296d4aec (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2008 / Esta dissertação de mestrado trata da interferência entre os sistemas de rede sem fio IEEE 802.11g e Bluetooth. Mais especificamente, foi analisado o impacto que transmissões Bluetooth causam em transmissões de dados IEEE 802.11g. Foram analisados cinco parâmetros: tempo de transmissão, taxa média de transmissão de pacotes, taxa média de transmissão de dados, número de pacotes perdidos e número de pacotes ACK duplicados. Por meio da comparação entre os resultados obtidos para esses parâmetros sem interferência Bluetooth e com interferência Bluetooth, foi possível determinar que a transmissão Bluetooth afetou a transmissão IEEE 802.11g. Os experimentos foram realizados para três distâncias entre os transmissores e receptores Bluetooth e Wi-Fi. Inicialmente, avaliou-se a interferência para a distância de 1,60 m. Em seguida, para 2,60 m e, por fim, para 4,60 m. Para as distâncias de 1,60 m e 2,60 m não havia obstáculos entre os dispositivos de transmissão e recepção. Para a distância de 4,60 m, havia uma parede de alvenaria. Os resultados obtidos mostraram que a interferência Bluetooth na transmissão IEEE 802.11g foi maior com o aumento da distância, sendo mais significativa para a distância de 4,60 m
2

Performance Parameters Of Wireless Virtual Private Network

Ikiz, Suheyla 01 January 2006 (has links) (PDF)
ABSTRACT PERFORMANCE PARAMETERS OF WIRELESS VIRTUAL PRIVATE NETWORK KZ, S&uuml / heyla Ms.c, Department of Information Systems Supervisor: Assoc. Prof. Dr. Nazife Baykal Co-Supervisor: Assist. Prof. Dr. Yusuf Murat Erten January 2006, 78 pages As the use of PC&rsquo / s and handheld devices increase, it expected that wireless communication would also grow. One of the major concerns in wireless communication is the security. Virtual Private Network (VPN) is the most secure solution that ensures three main aspect of security: authentication, accountability and encryption can use in wireless networks. Most VPNs have built on IP Security Protocol (IPSec) to support end-to-end secure data transmission. IPSec is a wellunderstood and widely used mechanism for wired network communication. Because, wireless networks have limited bandwidth and wireless devices have limited power and less capable CPU, the performance of the networks when VPN&rsquo / s are used is an important research area. We have investigated the use of VPNs in wireless LANs to provide end &ndash / to &ndash / end security. We have selected IPSec as the VPN protocol and investigated the effects of using IPSec on the throughput, packet loss, and delay of the wireless LANs. For this purpose, we have set up a test bed and based, our results on the actual measurements obtained from the experiments performed using the test bed. v The wireless LAN we have used is an 802.11g network and the results show that the performance of the network is adversely affected when VPN&rsquo / s are used but the degradation is not as bad as expected.
3

The Performance Evaluation of OFDM Based WLAN (IEEE 802.11a and 802.11g)

Shaikh, Kamil Mohiuddin January 2010 (has links)
ABSTRACT In the past decade there has been a steady growth in development and implementation of wireless Local Area Networks and emerged as in the largest sectors of the telecommunication industry. Wireless local area network (WLANs) provides connectivity, mobility, and much higher performance and achievable data rate. WLAN is a new medium of access technology in the Local Area Network (LAN) world. Mostly WLAN applications are used in public sectors such as airports, banks, hotels, offices, city centres because of the flexibility of the people. Orthongonal Frequency Division Multiplexing OFDM has been adopted by IEEE 802.11’s standard as a transmission technique for high data rate in WLANs. Now IEEE 802.11 standard has been expanded to a family of WLAN standards. 802.11a and 802.11g both are used Orthongonal Frequency Division Multiplexing (OFDM) but operate in different frequency bands. It is shown that 802.11a provides high speed throughout the entire coverage area and long term solution however it does not provide better solution in most cases as compared to IEEE 802.11g. Matlab Simulation model based on IEEE 802.11a/g using different modulation and demodulation techniques such as BPSK, QPSK and QAM to analysis the best performance of IEEE 802.11a/g with implementation of OFDM. Keywords: Orthongonal Frequency Division Multiplexing (OFDM), IEEE 802.11s family, Wireless Local Area Network, Simulation, MATLAB / Summary The objective of this research is to examine the performance of the IEEE 802.11a and IEEE 802.11g WLAN comparing through OFDM modulation techniques. It is found that IEEE 802.11a/g provides similar quality except IEEE 802.11g provides wider range but range is the controversial topic in WLAN medium. In the other hand IEEE 802.11a provides more channels in 5 GHz bands as well as have a good enough signal qualities but there is range limitation factor. Range limitation in the enterprise and public sectors can be adjusting through installations more APs. The main disadvantage of the 802.11g is the frequency band is common and interference from the other networking technology such as Bluetooth, 2.04 GHz cordless phone and IEEE 802.11a avoid this interference because its operate in 5.GHz bands. Consequently, all the simulation is a comparison between simulated BER for a computer system and theoretical BER for serial systems it has been proved through simulation results that theoretical BER and simulated BER under AWGN are good agreement with each other. It means that I and Q points on constellation are much closer to each other the data error can be reduced as well as transmission easily influenced to noise. 64 QAM modulations are much better than 16 QAM when BER decrease SNR will be increase because signal is stronger than noise. 64 QAM modulations need higher bandwidth and give an excellent data rates as compared to 16 QAM.
4

Análise do padrão IEEE 802.11g para a comunicação do sistema de controle distribuído de semáforos. / IEEE 802.11g standart analysis for communication of the distributed control system of traffic lights.

Miguel, Danilo de Souza 16 June 2015 (has links)
Este trabalho propõe a análise da comunicação sem fio para um sistema de controle distribuído de semáforos, a partir da revisão das literaturas, realização de simulações e experimentos, os quais consideram as especificações estabelecidas para o sistema de semáforos. As simulações e os experimentos se baseiam na avaliação do comportamento da comunicação perante a alteração de alguns parâmetros de configuração da rede. O estudo apresentado envolve análises relacionadas ao padrão IEEE 802.11g e às definições da camada física apresentadas nas especificações do padrão. Os métodos utilizados envolvem o estudo e experimentação de parâmetros relacionados à potência de transmissão e recepção, além de análise dos esquemas de modulação utilizados pelo padrão IEEE 802.11g. A metodologia aplicada a este trabalho envolve o conhecimento das características e capacidade dos esquemas de modulação responsáveis pela definição das taxas de transmissão. As análises mostram que a possibilidade de adequação dos parâmetros de configuração de rede, levando em consideração o cenário de aplicação, pode ser um fator essencial para o bom desempenho de todo o sistema. / This work proposes the analysis of wireless communication for a distributed control system of traffic lights, from the review of the literature and conducting simulations and experiments, which consider the specifications established for traffic light system. The simulations and experiments are based on the evaluation of the communication behavior towards changing some network configuration parameters. The study presented involves analysis related to the IEEE 802.11g standard and definitions of the physical layer shown in standard specifications. The methods used involve the study and testing of parameters related to power transmission and reception, and analysis of modulation schemes used by the IEEE 802.11g standard. The methodology applied to this work involves the knowledge of the characteristics and capacity of modulation schemes responsible for setting transmission rates. The analyses show that the possibility of adaptation network configuration parameters considering the application scenario may be an essential factor to the performance of the entire system.
5

Análise do padrão IEEE 802.11g para a comunicação do sistema de controle distribuído de semáforos. / IEEE 802.11g standart analysis for communication of the distributed control system of traffic lights.

Danilo de Souza Miguel 16 June 2015 (has links)
Este trabalho propõe a análise da comunicação sem fio para um sistema de controle distribuído de semáforos, a partir da revisão das literaturas, realização de simulações e experimentos, os quais consideram as especificações estabelecidas para o sistema de semáforos. As simulações e os experimentos se baseiam na avaliação do comportamento da comunicação perante a alteração de alguns parâmetros de configuração da rede. O estudo apresentado envolve análises relacionadas ao padrão IEEE 802.11g e às definições da camada física apresentadas nas especificações do padrão. Os métodos utilizados envolvem o estudo e experimentação de parâmetros relacionados à potência de transmissão e recepção, além de análise dos esquemas de modulação utilizados pelo padrão IEEE 802.11g. A metodologia aplicada a este trabalho envolve o conhecimento das características e capacidade dos esquemas de modulação responsáveis pela definição das taxas de transmissão. As análises mostram que a possibilidade de adequação dos parâmetros de configuração de rede, levando em consideração o cenário de aplicação, pode ser um fator essencial para o bom desempenho de todo o sistema. / This work proposes the analysis of wireless communication for a distributed control system of traffic lights, from the review of the literature and conducting simulations and experiments, which consider the specifications established for traffic light system. The simulations and experiments are based on the evaluation of the communication behavior towards changing some network configuration parameters. The study presented involves analysis related to the IEEE 802.11g standard and definitions of the physical layer shown in standard specifications. The methods used involve the study and testing of parameters related to power transmission and reception, and analysis of modulation schemes used by the IEEE 802.11g standard. The methodology applied to this work involves the knowledge of the characteristics and capacity of modulation schemes responsible for setting transmission rates. The analyses show that the possibility of adaptation network configuration parameters considering the application scenario may be an essential factor to the performance of the entire system.
6

Optimalizace bezdrátových WiFi distribuovaných sítí / Optimization of WiFi Distributed Nets

Žlůva, Ivan January 2009 (has links)
This thesis describes theoretic proposal and two practical realization of multi - point wireless network, first for communications between two endpoints and second for wireless signal coverage of a structured space. The wireless network is realized by the equipment working in unlicenced 2,4GHz and 5GHz ISM band. The wireless device are configured in three different wireless mods: WDS, WDS bridge and AP. This paper contains short information about IEEE 802.11a/b/g/n standard and associated proprietary wireless specifications. Practical workshop describes several variants connections and present the result of throughtput measurements, depending on wireless network topology.
7

Využití mobilních AP jednotek pro bezdrátové připojení koncových zařízení / Mobile AP Units Utilization of Wireless Connection for End User Devices

Nárožný, Tomáš January 2009 (has links)
The work deals with design and implementation of multi-point wireless network connecting selected end devices (IP cameras). The Access Points (AP) using frequency band 2.4 GHz establish the connection. They are connected using wireless distribution system (WDS). The work briefly describes standard IEEE 802.11g which is base of the design. Practical part is composed of network throughput measuring, signal strength measuring of access points with description and description of all other used devices.
8

Optimalizace bezdrátových WiFi distribuovaných sítí / Optimization of WiFi Distributed Nets

Žlůva, Ivan January 2010 (has links)
This thesis describes theoretic proposal and two practical realization of multi - point wireless network, first for communications between two endpoints and second for wireless signal coverage of a structured space. The wireless network is realized by the equipment working in unlicenced 2,4GHz and 5GHz ISM band. The wireless device are configured in three different wireless mods: WDS, WDS bridge and AP. This paper contains short information about IEEE 802.11a/b/g/n standard and associated proprietary wireless specifications. Practical workshop describes several variants connections and present the result of throughtput measurements, depending on wireless network topology.
9

Metodika měření kvality služeb ve Wi-Fi sítích / Methods for Quality of Service measurement in Wi-Fi networks

Bachan, Jiří January 2008 (has links)
This work deals with the wireless Wi-Fi networks, that used unlicenced ISM frequency band 2,4 GHz. These wireless networks are very extended in these days and used mainly for the Internet connection. With the multimedia data transfers expanding it’s necessary to ensure the specific quality of service QoS in wireless networks mainly for applications, which are sensitive to delay or packets lost. The main aim of this work is to describe Wi-Fi networks based on IEEE 802.11b/g/n standards, description of QoS techniques according to IEEE 802.11e standard and description of parameters describing QoS for the VoIP services. The practical part is divided on a two parts. The problems of measuring the radio link quality and the creation of simple program for quality of wireless connection analysis are solved in the first part. The second part incluledes measuring of the lost packets number in Wi-Fi network with the commercial application AirMagnet Laptop Wireless LAN Analyzer and measuring of the signal noise influence with the help of spectrum analyzer and vector signal generator.

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