In recent years, an increasing number of devices have been developed for operation in the bands allocated by the Federal Communications Commission (FCC) for license-free operation. Given the rules governing devices in these bands, it is possible for interference created by these devices to significantly reduce the overall capacity of these bands. Two such protocols are Bluetooth and IEEE 802.11b. Several methods have been presented in the literature for managing interference between these two devices. However, these approaches are generally not practical, since they either require the purchase of specialized hardware or do not comply with the current versions of existing protocols. In this dissertation, an approach is presented that is not only backwards-compatible, but requires the algorithm to be implemented in only a small subset of the devices operating in the local environment for the coexistence algorithm to function properly. An analytical solution for this coexistence approach when applied to generic networks is presented. A method is also presented for the backwards-compatible integration of some medium access control (MAC) protocols into Bluetooth devices. A case study of the Bluetooth/IEEE 802.11b coexistence problem is presented in this dissertation, as well as a proposed coexistence mechanism, collision-based multiple access (CBMA). A form of adaptive frequency hopping (AFH) is presented in this dissertation, as well as a combined CBMA/AFH strategy. The CBMA algorithm is shown be able to significantly reduce the impact of a Bluetooth link on an IEEE 802.11b link. The AFH algorithm is shown to have comparable performance to the CBMA algorithm. A combined CBMA/AFH algorithm presented, is shown to not only have an impact on the IEEE 802.11b link that is not greater than the CBMA-only implementation, but the Bluetooth link throughput is shown to be significantly greater than either the CBMA or AFH implementation alone. / Ph. D.

Submitted by Programa de P?s-Gradua??o Engenharia El?trica (ppgee@ifpb.edu.br) on 2018-04-17T16:59:08Z No. of bitstreams: 1 43- Thamyris da Silva Evangelista - DESENVOLVIMENTO DE SUPERF?CIE SELETIVA EM FREQU?NCIA RECONFIGUR?VEL BASEADA NA GEOMETRIA ESTRELA DE QUATRO BRA?OS PARA APLICA??O EM 2,4 GHz.pdf: 3077852 bytes, checksum: e604c3a3df9471f48941fe95027e6ad2 (MD5) / Approved for entry into archive by Programa de P?s-Gradua??o Engenharia El?trica (ppgee@ifpb.edu.br) on 2018-04-17T17:00:16Z (GMT) No. of bitstreams: 1 43- Thamyris da Silva Evangelista - DESENVOLVIMENTO DE SUPERF?CIE SELETIVA EM FREQU?NCIA RECONFIGUR?VEL BASEADA NA GEOMETRIA ESTRELA DE QUATRO BRA?OS PARA APLICA??O EM 2,4 GHz.pdf: 3077852 bytes, checksum: e604c3a3df9471f48941fe95027e6ad2 (MD5) / Made available in DSpace on 2018-04-17T17:00:16Z (GMT). No. of bitstreams: 1 43- Thamyris da Silva Evangelista - DESENVOLVIMENTO DE SUPERF?CIE SELETIVA EM FREQU?NCIA RECONFIGUR?VEL BASEADA NA GEOMETRIA ESTRELA DE QUATRO BRA?OS PARA APLICA??O EM 2,4 GHz.pdf: 3077852 bytes, checksum: e604c3a3df9471f48941fe95027e6ad2 (MD5) Previous issue date: 2018-03-26 / IFPB / Diante da atual demanda dos sistemas de telecomunica??es, as superf?cies seletivas em frequ?ncia, FSS ativas e passivas, v?m atraindo a aten??o de diversos grupos de pesquisa por suas in?meras aplica??es, tais como: refletores de antena, janelas eficientes, paredes inteligentes, entre outras. Neste cen?rio, neste trabalho ? apresentado o desenvolvimento de uma superf?cie seletiva em frequ?ncia reconfigur?vel baseada na geometria estrela de quatro bra?os para aplica??o na faixa de 2400-2483,5 MHz dos padr?es IEEE 802.11b/g/n (Wi-Fi) e IEEE 802.15 (Bluetooth). Como elemento de comuta??o foi utilizado o diodo PIN. S?o apresentados resultados num?ricos, obtidos utilizando o software comercial ANSYS Designer que se baseia no M?todo dos Momentos, MoM, e resultados experimentais, observando-se uma boa concord?ncia entre os mesmos. No estado ligado (ON), a partir da aplica??o de uma tens?o de V = 1,8 V, a FSS rejeita a faixa de frequ?ncia de 2,4 GHz. Para o estado desligado, (OFF) a FSS deixa de atenuar esta faixa de frequ?ncia. Tamb?m foram realizadas medi??es da intensidade do sinal de Wi-Fi com o aux?lio do software Homedale e os resultados obtidos foram bastante satisfat?rios, confirmando a efici?ncia da geometria proposta.

Dans ce travail de thèse, nous proposons d'utiliser la technologie ULB pour établir un nouveau système de communication haut débit Radio Impulsionnelle (IR-ULB), basé sur un nouveau schéma de modulation nommé M-OAM (M-Orthogonal Amplitude Modulation) et les formes d'ondes orthogonales MGF (Modified Gegenbaeur Function). Ce système est dédié aux applications sans fil à courte portée, notamment les communications multimédia et le transport intelligent (ITS). Les modulations M-OAM proposées, sont évaluées sous le canal AWGN et les canaux ULB à trajets multiples à savoir IEEE.802.15.3a et IEEE.802.15.4a. Les résultats de simulation montrent que la performance du système proposé, en terme de taux d'erreur binaire (BER), est du même ordre que celle des modulations ULB traditionnelles. En outre, les modulations M-OAM offrent un très haut débit de données avec une faible complexité d'implémentation. En effet, la conception d'un tel système doit certes fournir un très haut débit mais aussi servir un grand nombre d'utilisateurs simultanément avec une bonne qualité de service. Dans cette optique, une nouvelle technique d'accès multiple DS-MGF-OAM est proposée. Ce système multi-utilisateur fait usage de la technique DS-ULB et l'orthogonalité des impulsions MGF pour permettre une communication efficace avec un nombre maximal d'utilisateurs. Néanmoins, l'effet de trajets multiples réduit la qualité de la transmission. Ainsi, la contribution de deux architectures de réception dans l'amélioration des performances est étudiée, à savoir le récepteur RAKE et l'égaliseur MMSE (Minimum Mean Square Error). Cette étude montre que le système de communication M-OAM offre de bonnes performances en terme de qualité de services (QoS). Après l'étape de simulation, les résultats expérimentaux des systèmes proposés dans les environnements réelles sont analysés et discutés. Dans la dernière partie de ce document, nous avons réalisé un prototype de traitement en temps réel sur une plateforme FPGA, offrant des temps de calcul à 3GHz grâce à des algorithmes parallélisables sur des architectures re-configurables. / In this thesis, we propose to use the UWB technology to establish a new communications system Impulse Radio (IR-UWB), based on a new modulation scheme called M-OAM (Orthogonal M-Amplitude Modulation) and orthogonal waveforms MGF (Modified Gegenbauer Function). This system is dedicated to the short-range wireless applications, especially multimedia communications and intelligent transportation (ITS). The proposed modulations M-OAM, are evaluated under the AWGN channel and UWB multipath channel namely IEEE.802.15.3a and IEEE.802.15.4a. Simulation results show that the performance of the proposed system in terms of bit error rate (BER) is the same as that of traditional UWB modulations. In addition, M-OAM modulations offer the highest data rate with low complexity of implementation. Indeed, the design of a such system should certainly provide a very high speed but also serve a large number of concurrent users with good quality of service. In this context, a new multiple access technique DS-MGF-OAM is proposed. This multi-user system makes use of the DS-UWB technology and orthogonal pulses MGF to enable effective communication with a maximum number of users. However, the multi-path effect reduces the quality of the transmission. Thus, the contribution of two receiver architectures in performance improvement is studied, namely the RAKE receiver and MMSE (Minimum Mean Square Error) equalizer. This study shows that the M-OAM communication system offers good performance in terms of quality of service (QoS). Following the simulation step, the experimental results of the proposed systems in real environments are analyzed and discussed. In the last part of this document, we performed a real-time protoptype on an FPGA platform, offering calculation time of 3GHz through parallelizable algorithms on reconfigurable architectures.

Dans ces travaux de thèse, nous proposons un système de communication original permettant d’atteindre un haut débit et de répondre aux exigences de la qualité de service requise pour les communications courte portée dans le cadre du transport intelligent. Ce système se base sur la technologie Ultra Large Bande Impulsionnelle (IR-ULB) et sur un nouveau schéma de modulation nommé M-OAM (M-Orthogonal Amplitude Modulation). Les modulations M-OAM se basent sur le principe des modulations M-QAM en remplaçant les porteuses par des formes d’ondes ULB orthogonales de type MGF (Modified Gegenbauer Function). Ces modulations ont été évaluées sous les conditions d’un canal AWGN et des canaux IEEE 802.15.3a et IEEE 802.15.4a qui tiennent compte des paramètres réels de la route. En plus du haut débit exigé par les communications inter-véhiculaires, il faut assurer un échange d’informations simultané entre plusieurs utilisateurs de la route et garantir une bonne qualité de service. Dans cette optique, une nouvelle technique d’accès multiple adaptée est proposée. Chaque utilisateur a la possibilité d’utiliser la modulation OAM adéquate selon le débit désiré. Le récepteur de ce système se caractérise par un aspect intelligent grâce à l’intégration des principes de la Radio Cognitive (RC) qui permet de détecter l’arrivée du signal et d’identifier les paramètres de la modulation utilisée afin de s’y adapter d’une façon autonome. Une bonne qualité de service est assurée par la proposition d’une nouvelle technique de démodulation qui se base sur les Statistiques d’Ordres Supérieurs (SOS) permettant d’éliminer le bruit Gaussien. Les bonnes performances du système de communication M-OAM ainsi que l’ensemble des aspects proposés ont été validés expérimentalement au sein du laboratoire IEMN-DOAE. Dans la dernière partie de ce document nous avons présenté la réalisation d’un prototype de ce traitement en temps réel sur une plateforme FPGA, en exploitant des algorithmes parallélisables sur des architectures reconfigurables. / In this work of thesis, we propose an original communication system allowing to reach high data rate and to fulfill the requirements of quality of service necessary for the communications short range dedicated to intelligent transport. This system is based on the Ultra Wide Band Impulse (IR-ULB) technology and on new modulation scheme named M-OAM (M-states Orthogonal Amplitude Modulation). M-OAM modulations are based on the principle of modulations M-QAM by replacingthe carriers used for QAM modulation with orthogonal waveforms ULB type MGF (Modified Gegenbauer Function). These modulations were evaluated under the conditions of AWGN channel and IEEE 802.15 channels which take account of the real parameters of the road. Besides the high speed required by inter-vehicular communications, it is necessary to ensure simultaneous information exchange between several users of the road. Accordingly, new adaptive multiple access system is proposed. Each user has the possibility to use the adequate modulation OAM according to the desired speed. The receiver of this system is characterized by an intelligent aspect thanks to the integration of the principle of Cognitive Radio (RC) which makes it able to detect the signal arrival and to identify the parameters of the used modulation in order to adapt the demodulation in an autonomous way. A good quality of service is ensured by the proposed novel demodulation method based on the Higher Orders Statistics (HOS) to eliminate the Gaussian noise. The good performances of M-OAM communication system M-OAM as well as the whole of the suggested aspects are validated in experiments within IEMN-DOAE laboratory. In the last part of this document we presented the realization of prototype using real time processing developed on FPGA plateform and exploiting parallelisable algorithms on reconfigurable architectures.

Computer networks are in the scope of the IEEE organization normalized by the 802 board which currently comprises six working groups for wireless communications. IEEE 802.11 for wireless local area networks, IEEE  802.15 for wireless personal area networks, IEEE 802.16 for wireless metropolitan area networks, IEEE 802.20 for mobile broadband wireless access, IEEE 802.21 for media independent handover and IEEE 802.22 for wireless regional area networks. This master's thesis focuses on a security analysis of particular standards, describes threats, vulnerabilities, current security measures and mutually compares wireless specifications from a security point of view. The conclusion is devoted to overall evaluation of the project, to its contributions, possible enhancements and continuation in the form of consequential studies.