An important aspect of wireless networks is their dynamic behavior. The conventional protocol stack is inflexible as various protocol layers communicate in a strict manner. In such a case the layers are designed to operate under the worst conditions as opposed to adapting to changing conditions. This leads to inefficient use of spectrum and energy. Adaptation represents the ability of network protocols and applications to observe and respond to channel conditions. Traditional simulation methodologies independently model the physical and higher layers. When multiple layer simulations are required, an abstraction of one layer is inserted into the other to provide the multiple layer simulation. However, recent advances in wireless communication technologies, such as adaptive modulation and adaptive antenna algorithms, demand a cross layer perspective to this problem in order to provide a sufficient level of fidelity. However, a full simulation of both layers often results in excessively burdensome simulation run-times. The benefits and possible parametric characterization issues arising due to the cross-layer integration of lower physical and higher network layers are investigated in this thesis. The primary objective of investigating cross-layer simulation techniques is to increase the fidelity of cross-layer network simulations while minimizing the simulation runtime penalties. As a study of cross-layer system design a medium access control (MAC) scheme is studied for a MANET wherein the nodes are equipped with smart antennas. Traditional MAC protocols assume the use of omnidirectional antennas. Nodes with directional antennas are capable of transmitting in certain directions only and significantly reduce the chances of collision and increase the effective network capacity. MANETs using omni-directional antennas severely limit system performance as the entire space around a node up to its radio range is seen as a single logical channel. In this research a MAC protocol is studied that exploits space division multiple access at the physical layer. This is a strong example where physical and MAC design must be carried out simultaneously for adequate system performance. Power control is a very important in the design of cellular CDMA systems which suffer from the near-far problem. Finally, the interaction between successive interference cancellation (SIC) receivers at the physical layer and power control, which is a layer 2 radio resource management issue, is studied. Traffic for future wireless networks is expected to be a mix of real-time traffic such as voice, multimedia teleconferencing, and games and data traffic such as web browsing, messaging, etc. All these applications will require very diverse quality of service guarantees. A power control algorithm is studied, which drives the average received powers to those required, based on the QoS requirements of the individual users for a cellular CDMA system using SIC receivers. / Master of Science

Multi-hop wireless networks or ad-hoc networks face several limiting characteristics that make it difficult to support a multitude of applications. It is in this context that we find smart antennas to find significant applications in these networks, owing to their ability to alleviate most of these limitations. The focus of my research is thus to investigate the use of smart antennas in ad-hoc networks and hence efficiently design network protocols that best leverage their capabilities in communication. There are two parts to the proposed objective of designing efficient network protocols that pertain to the nature of the smart antenna network considered, namely, homogeneous and heterogeneous smart antenna networks. Unlike heterogeneous smart antenna networks, where different devices in the network employ different antenna technologies, homogeneous smart antenna networks consist of devices employing the same antenna technology. Further, in homogeneous smart antenna networks, different antenna technologies operating in different strategies tend to perform the best in different network architectures, conditions and application requirements. This motivates the need for developing a {em unified} framework for designing efficient communication (medium access control and routing) protocols for homogeneous smart antenna networks in general. With the objective of designing such a unified framework, we start by designing efficient MAC and routing protocols for the most sophisticated of the smart antenna technologies, namely multiple-input multiple-output (MIMO) links. The capabilities of MIMO links form a super-set of those possible with other antenna technologies. Hence, the insights gained from the design of communication protocols for MIMO links are then used to develop unified MAC and routing frameworks for smart antennas in general. For heterogeneous smart antenna networks, we develop theoretical performance bounds by studying the impact of increasing degree of heterogeneity on network throughput performance. Given that the antenna technologies are already unified in the network, unified solutions are not required. However, we do develop efficient MAC and routing protocols to best leverage the available heterogeneous capabilities present in the network. We also design efficient cooperation strategies that will further help the communication protocols in exploiting the available heterogeneous capabilities in the network to the best possible extent.

Current wireless network solutions are based on a link abstraction where a single co-channel transmitter transmits in any time duration. This model severely limits the performance that can be obtained from the network. Being inherently an extension of a wired network model, this model is also incapable of handling the unique challenges that arise in a wireless medium. The prevailing theme of this research is to explore wireless link abstractions that incorporate the broadcast and space-time varying nature of the wireless channel. Recently, a new paradigm for wireless networks which uses the idea of 'cooperative transmissions' (CT) has garnered significant attention. Unlike current approaches where a single transmitter transmits at a time in any channel, with CT, multiple transmitters transmit concurrently after appropriately encoding their transmissions. While the physical layer mechanisms for CT have been well studied, the higher layer applicability of CT has been relatively unexplored. In this work, we show that when wireless links use CT, several network performance metrics such as aggregate throughput, security and spatial reuse can be improved significantly compared to the current state of the art. In this context, our first contribution is Aegis, a framework for securing wireless networks against eavesdropping which uses CT with intelligent scheduling and coding in Wireless Local Area networks. The second contribution is Symbiotic Coding, an approach to encode information such that successful reception is possible even upon collisions. The third contribution is Proteus, a routing protocol that improves aggregate throughput in multi-hop networks by leveraging CT to adapt the rate and range of links in a flow. Finally, we also explore the practical aspects of realizing CT using real systems.

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No. of bitstreams: 2 Dissertação - Jonas Augusto Kunzler - 2015.pdf: 5934373 bytes, checksum: a736817202816bba60673f1a39184580 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2015-04-14 / New technologies that have emerged from the transistor advent enabled digital signal processing techniques were aggregated to systems operated or partially in analog improving performance of these systems. Added to this the use of sensor arrangements which made it possible to identify the directions of signals of interest and are used in critical areas of knowledge, such as in tracking radar systems; in astronomy; in sonar systems; mobile communications; the estimation of direction of arrival; in seismology and medical diagnosis and treatment. This work aims to study specific features of an estimation method of direction of arrival based on a linear array of sensors with special attention to mobile communications. Some methods have been proposed in order to get the position of a source of electromagnetic waves and can cite the MUSIC, the MODEX and SEAD, the latter of fundamental importance to this work because it is the basis of conducted research and because it is a new method, lacked further clarification with regard to the differential spectrum, their origin, meaning and importance, as well as obtaining an analytical expression to describe their conduct on the variables that compose the system. Based on eigenvalue decomposition of the correlation matrix has been observed that the differential spectrum is basically a matrix norm calculation, with the largest eigenvalue of the matrix is ​​also standard 2-induced vector. It was proposed to use the Frobenius norm which is simpler to be computed, and consequently requires less computational effort. Moreover, the behavior of the angular spectrum calculated using the Frobenius norm is fully described by the sum of cosines with the formulation described for each part which composes the calculation of the standard. Through this outcome was possible to analyze aspects related to angular resolution, the number of signal sources, the number of sensors, the influence of noise and the correlation between sources. / Novas tecnologias que surgiram a partir do advento transistor permitiram técnicas de processamento digital de sinais fossem agregadas a sistemas que operavam ou parcialmente de forma analógica aprimorando o desempenho desses sistemas. Soma-se a isto a utilização de arranjos de sensores que possibilitaram a identificação das direções dos sinais de interesse e são empregados em importantes áreas do conhecimento, como por exemplo, em sistemas de rastreamento por radar; na Astronomia; em Sistemas sonares; nas comunicações móveis; na estimação de direção de chegada; na sismologia e no diagnóstico e tratamento médico. Este trabalho tem como objetivo estudar características específicas de um método de estimação de direção de chegada baseado em um arranjo linear de sensores com atenção especial em comunicações móveis. Alguns métodos foram propostos com o fim de obter a posição de uma fonte de ondas eletromagnéticas, podendo-se citar o MUSIC, o MODEX e o SEAD, este último de fundamental importância para este trabalho, pois, ele é a base da investigação conduzida e por se tratar de um método novo, carecia de mais esclarecimentos no que diz respeito ao espectro diferencial, sua origem, significado e importância, como também a obtenção de uma expressão analítica que descrevesse seu comportamento em função das variáveis que compões o sistema. Baseado na decomposição em autovalores da matriz de correlação observou-se que o espectro diferencial é basicamente um cálculo de norma matricial, sendo que o maior autovalor da matriz é também a norma 2 induzida por vetor. Propôs-se a utilização da norma de Frobenius que é mais simples de ser calculada e, consequentemente, exige menos esforço computacional. Além disso, o comportamento do espectro angular calculado com a norma de Frobenius é totalmente descrito através da soma de cossenos com a formulação descrita para cada parcela que compõe o cálculo da norma. Através deste resultado foi possível analisar aspectos referentes à resolução angular, ao número de fontes de sinal, ao número de sensores, à influência do ruído e à correlação entre as fontes.

Abstract In this doctoral thesis, initial code synchronization (i.e., code acquisition) of a direct sequence spread spectrum (DS/SS) system is studied when a smart antenna is used in a receiver. Code synchronization means time synchronization of the used spreading code in the receiver. After an introduction to the topic, a literature review of code acquisition is presented. In addition, a review of the results in the literature under fading, data modulation, Doppler, intentional interference, multiple-access interference, other system interference, and multiple antennas is given. After that, an overview of the smart antennas, especially focusing on digital beamforming and direction-of-arrival (DOA) estimation algorithms is presented. The end part of the thesis concentrates on the author’s own research of the topic. Original articles of this article dissertation have been classified according to their contents into two groups. The first group covers DS/SS code acquisition performance in intentional interference by exploiting how well different beamforming algorithms can eliminate narrowband and wideband interfering signals in the case, where the DOA of the desired signal is known. The obtained results show that most spatial beamforming algorithms are capable of cancelling multiple different types of interfering signals if they are not arriving from the same direction as the desired signal. If angle separation between desired and interfering signals is not sufficient, then more complex methods have to be used. The second group of articles focuses on a theoretical analysis of synchronization probabilities and mean acquisition times. If the DOA of the desired signal is unknown, the whole angular uncertainty region can be divided into small angular cells using beamforming techniques, as is proposed in the literature. Then there is a two-dimensional (delay-angle) acquisition problem. In this thesis, the research work of that area is expanded to cover also advanced beamforming techniques, since they offer increased interference suppression capability. It is shown that the code acquisition performance of the delay-angle method can be improved in some cases by adding a DOA estimator into the system, because it may reduce the number of required angular cells. In addition, such a minimum mean square error (MMSE) beamforming structure is proposed, where only one period of the known pseudo noise spreading code is used as a reference signal. The method was shown to have better acquisition performance than the delay-angle method has, since MMSE beamforming does not need DOA information. However, in this thesis, such a method was not found which outperforms the rest of the methods in all scenarios. / Tiivistelmä Tässä väitöstyössä tutkitaan suorahajotushajaspektrijärjestelmän (DS/SS, direct sequence spread spectrum) koodisynkronoinnin etsintävaihetta, kun vastaanottimessa käytetään älyantennia. Koodisynkronoinnilla tarkoitetaan järjestelmän käyttämän hajotuskoodin ajastuksen synkronointia vastaanottimessa. Johdannon jälkeen esitetään kirjallisuuskatsaus koodisynkronointiin sekä tuodaan esille kirjallisuudesta löytyviä tutkimustuloksia aihepiiristä seuraavissa tilanteissa: häipyvä kanava, Doppler-ilmiö, tahallinen häirintä, monikäyttöhäiriö, muiden järjestelmien aiheuttama häiriö sekä moniantennijärjestelmät. Tämän jälkeen esitetään yleiskatsaus älyantenneihin kohdistuen erityisesti digitaalisiin keilanmuodostus- sekä suuntaestimointialgoritmeihin. Työn loppuosa keskittyy kirjoittajan omaan tutkimukseen aiheesta. Tämän nippuväitöskirjan alkuperäiset artikkelit on luokiteltu kahteen ryhmään niiden sisältöön perustuen. Ensimmäinen ryhmä käsittelee DS/SS-järjestelmän koodisynkronoinnin etsintävaiheen suorituskykyä tahallisessa häirinnässä tutkimalla, miten hyvin erilaiset keilanmuodostusalgoritmit kykenevät poistamaan kapea- ja leveäkaistaisia häirintäsignaaleja tilanteessa, jossa hyötysignaalin tulosuunta tiedetään. Tutkimustulokset osoittavat, että monet tilatason keilanmuodostusalgoritmit kykenevät poistamaan useita erityyppisiä häirintäsignaaleita, jos ne eivät saavu hyötysignaalin kanssa samasta suunnasta. Mikäli kulmaero hyöty- ja häirintäsignaalien välillä ei ole riittävä, joudutaan käyttämään rakenteeltaan monimutkaisempia menetelmiä. Toinen ryhmä artikkeleita keskittyy synkronointiin liittyvien todennäköisyyksien ja keskimääräisen etsintäajan teoreettiseen analyysiin. Jos hyötysignaalin tulosuunta on tuntematon, voidaan kulmaepävarmuusalue jakaa pieniin kulmasoluihin käyttäen keilanmuodostustekniikoita, kuten kirjallisuudessa esitetään. Tällöin kyseessä on kaksiulotteinen (viive-kulma) etsintäongelma. Tässä työssä kyseistä tutkimusaihetta laajennetaan koskemaan myös edistyneet keilanmuodostusmenetelmät, koska ne tarjoavat parantuneen häiriönvaimennuskyvyn. Työssä osoitetaan, että viive-kulma menetelmän suorituskykyä voidaan parantaa joissakin tilanteissa lisäämällä järjestelmään suuntaestimaattori, koska se saattaa vähentää tarvittavien kulmasolujen lukumäärää. Lisäksi tutkitaan sellaista pienimmän keskineliövirheen (MMSE, minimum mean square error) keilanmuodostusmenetelmää, jossa ainoastaan yhtä hajotuskoodin koodijaksoa käytetään opetukseen. Kyseisellä menetelmällä todettiin olevan parempi suorituskyky kuin viive-kulma etsinnällä, koska MMSE-menetelmä ei tarvitse suuntainformaatiota. Tässä työssä ei kuitenkaan löydetty yhtä sellaista menetelmää, jonka suorituskyky on muita parempi kaikissa tilanteissa.

Over the last few years, wireless cellular communications has experienced rapid growth in the demand for provision of high data rate wireless multimedia services. This fact motivates the need to find ways to improve the spectrum efficiency of wireless communication systems. Smart or adaptive antennas have emerged as a promising technology to enhance the spectrum efficiency of present and future wireless communications systems by exploiting the spatial domain. The aim of this thesis is to investigate smart antenna applications for Direct Sequence Code Division Multiple Access (DS-CDMA) systems. CDMA is chosen as the platform for this thesis work since it has been adopted as the air-interface technology by the Third Generation (3G) wireless communication systems. The main role of smart antennas is to mitigate Multiple Access Interference (MAI) by beamforming (i.e. spatial filtering) operation. Therefore, irrespective of a particular wireless communication system, it is important to consider whether a chosen array configuration will enable optimal performance. In this thesis an initial assessment is carried out considering linear and circular array of dipoles, that can be part of a base station antenna system. A unified and systematic approach is proposed to analyse and compare the interference rejection capabilities of the two array configurations in terms of the Signal to Interference Ratio (SIR) at the array output. The theoretical framework is then extended to include the effect of mutual coupling, which is modelled using both analytical and simulation methods. Results show that when the performance is averaged over all angles of arrival and mutual coupling is negligible, linear arrays show similar performance as circular arrays. Thus in the remaining part of this thesis, only linear arrays are considered. In order to properly evaluate the performance of smart antenna systems, a realistic channel model is required that takes into account both temporal and spatial propagation characteristics of the wireless channel. In this regard, a novel parameterized physical channel model is proposed in this thesis. The new model incorporates parameters such as user mobility, azimuth angle of arrival, angle spread and Doppler frequency, which have critical influence on the performance of smart antennas. A mathematical formulation of the channel model is presented and the proposed model is implemented in software using Matlab. The statistics of the simulated channels are analysed and compared with theory to confirm that the proposed model can accurately simulate Rayleigh and Rician fading characteristics. To assist system planners in the design and deployment of smart antennas, it is important to develop robust analytical tools to assess the impact of smart antennas on cellular systems. In this thesis an analytical model is presented for evaluating the Bit Error Rate (BER) of a DS-CDMA system employing an array antenna operating in Rayleigh and Rician fading environments. The DS-CDMA system is assumed to employ noncoherent M-ary orthogonal modulation, which is relevant to IS-95 CDMA and cdma2000. Using the analytical model, an expression of the Signal to Interference plus Noise Ratio (SINR) at the output of the smart antenna receiver is derived, which allows the BER to be evaluated using a closed-form expression. The proposed model is shown to provide good agreement with the (computationally intensive) Monte Carlo simulation results and can be used to rapidly calculate the system performance for suburban and urban fading environments. In addition to MAI, the performance of CDMA systems is limited by fast fading. In this context, a hybrid scheme of beamforming and diversity called Hierarchical Beamforming (HBF) is investigated in this thesis to jointly combat MAI and fading. The main idea behind HBF is to divide the antenna elements into widely separated groups to form subbeamforming arrays. The performance of a hierarchical beamforming receiver, applied to an IS-95 CDMA system, is compared with smart antenna (conventional beamforming) receiver and the effect of varying the system and channel parameters is studied. The simulation results show that the performance of hierarchical beamforming is sensitive to the operating conditions, especially the value of the azimuth angle spread. The work presented in this thesis has been published in part in several journals and refereed conference papers, which reflects the originality and significance of the thesis contributions.

Over the last few years, wireless cellular communications has experienced rapid growth in the demand for provision of high data rate wireless multimedia services. This fact motivates the need to find ways to improve the spectrum efficiency of wireless communication systems. Smart or adaptive antennas have emerged as a promising technology to enhance the spectrum efficiency of present and future wireless communications systems by exploiting the spatial domain. The aim of this thesis is to investigate smart antenna applications for Direct Sequence Code Division Multiple Access (DS-CDMA) systems. CDMA is chosen as the platform for this thesis work since it has been adopted as the air-interface technology by the Third Generation (3G) wireless communication systems. The main role of smart antennas is to mitigate Multiple Access Interference (MAI) by beamforming (i.e. spatial filtering) operation. Therefore, irrespective of a particular wireless communication system, it is important to consider whether a chosen array configuration will enable optimal performance. In this thesis an initial assessment is carried out considering linear and circular array of dipoles, that can be part of a base station antenna system. A unified and systematic approach is proposed to analyse and compare the interference rejection capabilities of the two array configurations in terms of the Signal to Interference Ratio (SIR) at the array output. The theoretical framework is then extended to include the effect of mutual coupling, which is modelled using both analytical and simulation methods. Results show that when the performance is averaged over all angles of arrival and mutual coupling is negligible, linear arrays show similar performance as circular arrays. Thus in the remaining part of this thesis, only linear arrays are considered. In order to properly evaluate the performance of smart antenna systems, a realistic channel model is required that takes into account both temporal and spatial propagation characteristics of the wireless channel. In this regard, a novel parameterized physical channel model is proposed in this thesis. The new model incorporates parameters such as user mobility, azimuth angle of arrival, angle spread and Doppler frequency, which have critical influence on the performance of smart antennas. A mathematical formulation of the channel model is presented and the proposed model is implemented in software using Matlab. The statistics of the simulated channels are analysed and compared with theory to confirm that the proposed model can accurately simulate Rayleigh and Rician fading characteristics. To assist system planners in the design and deployment of smart antennas, it is important to develop robust analytical tools to assess the impact of smart antennas on cellular systems. In this thesis an analytical model is presented for evaluating the Bit Error Rate (BER) of a DS-CDMA system employing an array antenna operating in Rayleigh and Rician fading environments. The DS-CDMA system is assumed to employ noncoherent M-ary orthogonal modulation, which is relevant to IS-95 CDMA and cdma2000. Using the analytical model, an expression of the Signal to Interference plus Noise Ratio (SINR) at the output of the smart antenna receiver is derived, which allows the BER to be evaluated using a closed-form expression. The proposed model is shown to provide good agreement with the (computationally intensive) Monte Carlo simulation results and can be used to rapidly calculate the system performance for suburban and urban fading environments. In addition to MAI, the performance of CDMA systems is limited by fast fading. In this context, a hybrid scheme of beamforming and diversity called Hierarchical Beamforming (HBF) is investigated in this thesis to jointly combat MAI and fading. The main idea behind HBF is to divide the antenna elements into widely separated groups to form subbeamforming arrays. The performance of a hierarchical beamforming receiver, applied to an IS-95 CDMA system, is compared with smart antenna (conventional beamforming) receiver and the effect of varying the system and channel parameters is studied. The simulation results show that the performance of hierarchical beamforming is sensitive to the operating conditions, especially the value of the azimuth angle spread. The work presented in this thesis has been published in part in several journals and refereed conference papers, which reflects the originality and significance of the thesis contributions.

Made available in DSpace on 2016-08-17T14:52:41Z (GMT). No. of bitstreams: 1 Dissertacao-WilanderTestonePereiraSilva.pdf: 3903191 bytes, checksum: b91ff906a27937df64d75b330c6ea137 (MD5) Previous issue date: 2016-03-11 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / In this dissertation we present a research in aspects of stochastic modeling, convergence and applications of least mean square (LMS) algorithm, normalized least mean square (NLMS) algorithm and proportionate normalized least mean square (PNLMS) algorithm. Specifically, the aim is to address the LMS algorithm in your extension, defining his concepts, demonstrations of properties, algorithms and analysis of convergence, Learning Curve and Misadjustment of the algorithm in question. Within of the context of sensor networks and spatial filtering is evaluated the performance of the algorithms by the learning curve of the referred algorithms for arrangements of adaptive antennas. In the intrinsic context of the application in electrical engineering, in area of telecommunications that seek the best alternative and aims to optimize the process of transmission/reception to eliminate interference, and the least amount of elements in adaptive antenna arrays, which they are known as smart antenna, which aims to reach a signal noise ratio for small value, with appropriate number of elements. The performance of the LMS algorithm is evaluated in sensor networks that is characterized by an antenna array. Results of computer simulations for different scenarios of operation show that the algorithms have good numerical results of convergence to a suitable choice of the parameters related with the rate of learning that are associated with their average curves and the beamforming of the smart antenna array. / Nesta dissertação de mestrado apresenta-se uma investigação em aspectos de modelagem estocástica, convergência e aplicações dos algoritmos de mínimos quadrados médio (LMS), mínimos quadrados médio normalizado (NLMS) e mínimos quadrados médio normalizado proporcional (PNLMS). Particularmente, aborda-se o Algoritmo LMS em sua extensão, definindo conceitos, demonstrações de propriedades, algoritmos e análise de convergência, Curva de Aprendizagem e Desajuste do referido algoritmo. Dentro do contexto de redes de sensores e filtragem espacial avalia-se o desempenho dos algoritmos por meio da curva de aprendizagem dos referidos algoritmos para os arranjos de antenas adaptativas. No contexto intrínseco da aplicação em engenharia elétrica, isto é, na área de telecomunicações procura-se a melhor alternativa e almeja-se a otimização do processo de transmissão/recepção para eliminar interferências e a menor quantidade de elementos em arranjos de antenas adaptativas, que são conhecidas como antenas inteligentes, e que tem como objetivo atingir uma relação Sinal Ruído para valor pequeno, com número adequado de elementos. O desempenho do algoritmo LMS é avaliado em redes de sensores que é caracterizada por um arranjo de antenas. Resultados de simulações computacionais para diferentes cenários de operação mostram que os algoritmos apresentam bons resultados numéricos de convergência para uma escolha adequada dos parâmetros relacionados com a taxa de aprendizagem que são associadas com suas curvas médias e com a conformação de feixes do arranjo em antenas inteligentes.

In this thesis the possibilities of smart antenna systems in wireless mesh networks are examined. With respect to the individual smart antenna tradeoffs, a routing protocol (Modified HWMP, MHWMP) for IEEE 802.11s mesh networks is presented, that exploits the full range of benefits provided by smart antennas: MHWMP actively switches between the PHY-layer transmission/reception modes (multiplexing, beamforming and diversity) according to the wireless channel conditions. Spatial multiplexing and beamforming are used for unicast data transmissions, while antenna diversity is employed for efficient broadcasts. To adapt to the directional channel environment and to take full benefit of the PHY capabilities, a respective MAC scheme is employed. The presented protocol is tested in extensive simulation and the results are examined.

In this thesis the possibilities of smart antenna systems in wireless mesh networks are examined. With respect to the individual smart antenna tradeoffs, a routing protocol (Modified HWMP, MHWMP) for IEEE 802.11s mesh networks is presented, that exploits the full range of benefits provided by smart antennas: MHWMP actively switches between the PHY-layer transmission/reception modes (multiplexing, beamforming and diversity) according to the wireless channel conditions. Spatial multiplexing and beamforming are used for unicast data transmissions, while antenna diversity is employed for efficient broadcasts. To adapt to the directional channel environment and to take full benefit of the PHY capabilities, a respective MAC scheme is employed. The presented protocol is tested in extensive simulation and the results are examined.:1 Introduction 2 Wireless Mesh Networks 3 IEEE 802.11s 4 Smart Antenna Concepts 5 State of the Art: Wireless Mesh Networks with Smart Antennas 6 New Concepts 7 System Model 8 Results and Discussion 9 Conclusion and Future Work