International Telemetering Conference Proceedings / October 20-23, 2003 / Riviera Hotel and Convention Center, Las Vegas, Nevada / This paper addresses the physical and MAC layer performance of the IEEE 802.11b wireless local area networking (WLAN) standard in range-extended outdoor applications for high speed network platforms. Physical layer performance is quantified by bit error rate (BER) and packet error rate (PER) vs. range performance as well as acquisition and tracking performance considering Doppler effects caused by such high-speed platforms. This performance assessment is ascertained through the use of modeling and simulation and hardware-in-the-loop testing.

International Telemetering Conference Proceedings / October 21, 2002 / Town & Country Hotel and Conference Center, San Diego, California / The US Army’s Yuma Proving Ground (YPG) uses a wireless local area network (WLAN) to gather test data. It is desired to extend this WLAN to support tests of gun-launched munitions where miniature and rugged data acquisition hardware will be required. The Two Way Robust Acquisition of Data (2-RAD) program has been initiated under the Central Test and Evaluation Investment Program (CTEIP) to develop a process to expand the use of WLAN technology, which is now primarily used at YPG for internal ballistic test data acquisition.

International Telemetering Conference Proceedings / October 20-23, 2003 / Riviera Hotel and Convention Center, Las Vegas, Nevada / Tests for missile defense systems are very complex, and present challenging issues for the extraction of target lethality data. Future tests will involve the use of multiple interceptors and targets with some of these assets following over-the-horizon (OTH) trajectories. The use of wireless local area network (WLAN) technologies for the acquisition of test data offers a novel approach to manage data bandwidths and link margins over-the-air (OTA) as functions of time and asset. Notional test scenarios are examined for the suitability of WLAN technologies to missile defense intercept testing.

La gestion performante de la mobilité et l'amélioration des performances des couches basses sont deux enjeux fondamentaux dans le contexte des réseaux sans fil. Cette thèse apporte des solutions originales et innovantes qui visent à répondre à ces deux problématiques empêchant à ce jour d'offrir des possibilités de communication performantes et sans couture aux usagers mobiles accédant à l'Internet via des réseaux d'accès locaux sans fil (WLAN). Ces solutions se distinguent en particulier par l'impact minimum qu'elles ont sur les protocoles standards de l'Internet (niveaux transport et réseau) ou de l'IEEE (niveaux physique et liaison de données). S'inscrivant dans les paradigmes de "bout en bout" et "cross-layer", notre architecture permet d'offrir des solutions efficaces pour la gestion de la mobilité : gestion de la localisation et des handover en particulier. En outre, nous montrons que notre approche permet également d'améliorer l'efficacité des transmissions ainsi que de résoudre efficacement plusieurs syndromes identifiés au sein de 802.11 tels que les anomalies de performance, l'iniquité entre les flux et l'absence de contrôle de débit entre la couche MAC et les couches supérieures. Cette thèse résout ces problèmes en combinant des modèles analytiques, des simulations et de réelles expérimentations. Ces mécanismes adaptatifs ont été développés et intégrés dans une architecture de communication qui fournit des services de communication à haute performance pour réseaux sans fils tels que WIFI et WIMAX.

<p>This thesis describes the interference problem between IEEE 802.11 and Bluetooth. These well established communication standards are often used together simultaneously. Since both standards operate in the ISM-band at 2.45 GHz, they interfere with each other. In addition to this, interference from e.g. microwave ovens, heating processes, electric motors and cordless phones also occurs on the ISM-band. Due to this interference problem, a model has been developed in MATLAB to further investigate these interferences and the effects for the user.</p><p>The interference is modelled using the well known Class-A model for impulsive noise. The interference model is parameterized in the model and therefore the noise source(s) is described by a set of parameters derived from real measurements. Models for IEEE 802.11 legacy/b and Bluetooth are based on work published on the user community of MATHWORKS. To get a measure of performance, results from the model are presented as BER (Bit Error Rates) and PER (Packet Error Rates). When Bluetooth is used as a voice link, sound quality can also be performance evaluated directly by simply listening to a voice output file. To be able to track down a specific problem cause, measuring tools have also been included in the model to gain insight into what is causing bit/packet error.</p><p>A model describing the interference problem has been developed describing the real world usage of the standards by the use of state machines. Due to the complexity of the problem, and also for the model to be user friendly, this thesis is not composed of a thorough mathematical derivation describing BER probability for different modulation forms. The derivations for these has already been done and is therefore summarized and compared to when the model is validated. The model has been developed as a proof of concept for further work to fully support the current and coming IEEE standards for IEEE 802.11 and Bluetooth.</p>

This thesis describes the interference problem between IEEE 802.11 and Bluetooth. These well established communication standards are often used together simultaneously. Since both standards operate in the ISM-band at 2.45 GHz, they interfere with each other. In addition to this, interference from e.g. microwave ovens, heating processes, electric motors and cordless phones also occurs on the ISM-band. Due to this interference problem, a model has been developed in MATLAB to further investigate these interferences and the effects for the user. The interference is modelled using the well known Class-A model for impulsive noise. The interference model is parameterized in the model and therefore the noise source(s) is described by a set of parameters derived from real measurements. Models for IEEE 802.11 legacy/b and Bluetooth are based on work published on the user community of MATHWORKS. To get a measure of performance, results from the model are presented as BER (Bit Error Rates) and PER (Packet Error Rates). When Bluetooth is used as a voice link, sound quality can also be performance evaluated directly by simply listening to a voice output file. To be able to track down a specific problem cause, measuring tools have also been included in the model to gain insight into what is causing bit/packet error. A model describing the interference problem has been developed describing the real world usage of the standards by the use of state machines. Due to the complexity of the problem, and also for the model to be user friendly, this thesis is not composed of a thorough mathematical derivation describing BER probability for different modulation forms. The derivations for these has already been done and is therefore summarized and compared to when the model is validated. The model has been developed as a proof of concept for further work to fully support the current and coming IEEE standards for IEEE 802.11 and Bluetooth.

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Made available in DSpace on 2016-04-04T18:31:32Z (GMT). No. of bitstreams: 1 Luiz Henrique Biazotto.pdf: 2826699 bytes, checksum: ea3eea233d66bf1af34e5d7f5d20420d (MD5) Previous issue date: 2012-06-28 / Nowadays, the growth of energy consumption is a global concern due to the possibility of having lack of primary sources. Specially, the consume of electrical energy associated with communications network also eached significantly levels. In this context, researches related to energy efficiency are extremely important.Therefore, this work aims to evaluate the consumption of electrical energy related to IEEE802.11 networks, searching for the relation between this consumption and different parameters of QoS. / Atualmente, o crescimento do consumo de energia el?trica se constitui em preocupa??o mundial, devido ? possibilidade de escassez das fontes prim?rias. Em especial, o consumo de energia el?trica associado ?s redes de comunica??o tamb?m atingiu n?veis significativos. Nesse contexto, pesquisas associadas ? ?rea de efici?ncia energ?tica s?o de fundamental import?ncia. Assim, este trabalho teve por objetivo avaliar o consumo de energia el?trica associado a redes IEEE802.11, investigando a rela??o dessa grandeza com diferentes par?metros de Qualidade de Servi?o (QoS).

Cette thèse traite de l'utilisation des réseaux locaux sans fil dans un environnement industriel. Nous traitons l'impact des conditions de propagation et leur implémentation, sur des outils de simulations. La première partie s'intéresse au choix du modèle par des méthodes analytiques appliquées sur des mesures. La comparaison des performances obtenues dans un site avec les résultats de simulations montre une nette différence. Elle nous a permis de conclure que les modèles classiques ne permettent pas de simulations pertinentes pour un tel contexte. Pour ces raisons, nous proposons une nouvelle façon de modéliser les conditions de propagation. Notre modèle appelé "split model" permet de distinguer : liens entre stations et point d'accès des liens entre stations. Nous avons utilisé le modèle dans la simulation pour étudier les performances dans une cellule en mode infrastructure de la norme 802.11. Les résultats montrent que des collisions au niveau du point d'accès sont constatées et en résulte une dégradation des performances pour laquelle les mécanismes prévus pour compenser l'effet du terminal caché (RTS/CTS) se sont montrés inefficaces. L'utilisation du split model dans un processus de simulation met en avant les effets dus a l'existence de ces zones cachées et permet d'avoir des résultats obtenus par simulation plus représentatifs du comportement d'une cellule recouvrant une chaîne de production.

Telecommunications is converging on the use of IP based networks. Due to the low cost of VoIP applications, they are being increasingly used instead of conventional telephony services. IEEE802.11 WLANs are already widely used both commercially and domestically. VoIP applications will also expand from usage over wired networks to voice communications over IEEE802.11 WLANs. This is known as VoWLAN. The use of VoWLAN may reach the maximum capacity of a wireless channel if there are many simultaneous VoIP calls operating close to each other. There is much published research based on a single IEEE802.11 infrastructure WLAN concluding that packet loss, transmission efficiency and latency issues are the major challenges limiting the VoWLAN capacity. The VoIP service quality will drop sharply when the demands exceed the WLAN’s capacity. This thesis demonstrates that these challenges also apply to distributed WLANs. To extend these findings from the existing research, the analysis in this thesis indicates that the capacity of a single IEEE802.11 WLAN channel is 12 VoIP calls. When the number of simultaneous VoIP calls is within the capacity, the WLAN can deliver more than 90% of the voice packets to the receiver within 150 ms (the lowest network performance for supporting acceptable VoIP service). However, as soon as the traffic loads are beyond the wireless channel capacity e.g. the number of simultaneous VoIP calls is greater than 13, the VoIP service quality catastrophically collapses. When the capacity is exceeded there are almost no voice packets that can be delivered to the receiver within 150 ms. Our research results indicate that the delay accumulation for voice packets in the transmitter’s outgoing buffer causes this problem. Our research also found that dropping ‘stale’ voice packets that are already late for delivery to the receiver can give more transmission opportunities to those voice packets that may still be delivered in time. This thesis presents a new strategy called Active Cleaning Queue (ACQ) which actively drops ‘stale’ voice packets from the outgoing buffer and prevents the accumulation of delay in congested conditions. When ACQ is applied in a saturated wireless channel the network performance for supporting VoIP traffic was found to gradually decrease proportional to the numbers of simultaneous VoIP calls rather than catastrophically collapse. There is also published research suggesting that the aggregation of packets can improve the efficiency of WLAN transmissions. An algorithm called Small Packet Aggregation for Wireless Networks (SPAWN) is also presented in this thesis to improve transmission efficiency of small voice packets in WLANs without introducing further delay to VoIP traffic. The evaluation result shows that after applying the SPAWN algorithm, the VoIP capacity of a single wireless channel can be extended up to 24 simultaneous calls.