This thesis investigates various aspects of bandwidth allocation and scheduling in the Medium Access Control (MAC) layer of IEEE 802.16 systems. We highlight the important aspects of designing a scheduler and describe the scheduler design problem from a general perspective. That is, we provide a scheduler design framework driven by a set of objectives defined for the systems. In addition, we include Subscriber Station differentiation into our scheduler design. This approach is comprehensive, as it covers the requirements of both the network provider and the end users. In developing the framework, we discuss the importance of achieving customer satisfaction. This leads to an interesting objective that maximises the number of satisfied customers, rather than network centric objectives, such as fairness. We contend that providing fairness to customers does not necessarily achieve the best outcome for customer satisfaction and artificially limits the choices available to service providers. In order to maximise the number of satisfied customers, we analyse in detail the Dual-Queue (DQ) scheduling discipline proposed by Hayes et al. [2]. The DQ algorithms of Hayes’ work are focused on wireline networks, and are not directly deployable in an 802.16 environment, as we discuss in this thesis. We propose a modified DQ implementation for 802.16 systems to handle real-time services. In 802.16 systems, there are two scheduling processes that we need to consider: Downlink (DL) scheduling for data transmission from the Base Station to the Subscriber Stations and Uplink (UL) scheduling for data transmission from the Subscriber Stations to the Base Stations. We investigate the DL and UL implementations separately because the UL scheduling process is more complicated due to the fundamentally distributed nature of the problem. We demonstrate that our proposed approach is able to operate effectively in an 802.16 system. We then compare the performance of our proposed DL and UL Dual- Queue schedulers to a Weighted Fair Queue scheduler in noisy environments, where re-transmissions are required. In addition, we also compare our proposed schedulers to an enhanced Weighted Fair Queue scheduler with an Explicit Packet Dropping mechanism. Furthermore, we show that our Dual-Queue system can handle mixed traffic profiles, such as video and voice. Having proposed a DQ implementation that maximises the number of satisfied customers, we investigate alternative objectives that the DQ scheduler may try to achieve. We find that our proposed DQ implementation may fail to achieve these alternative objectives, and hence, we remedy this shortfall by proposing the Priority- Based Dual-Queue scheduler, which is made up of multiple DQs differentiated by the priority classes of connections. That is, each priority class is handled in a separate DQ. The Priority-Based Dual-Queue scheduler ensures connections that belong to the highest priority class are served ahead of connections that belong to lower priority classes at all times, even when there are changes in the priority class of connections in the system. Lastly, we investigate the benefits of carrying out the DQ scheduling for both the DL and UL of an 802.16 network jointly. We first investigate a scenario where the network consists of only one-directional connections. We propose a joint scheme that is able to maximise the number of satisfied one-directional connections in the network. We then extend our investigation to another scenario where the network consists of bi-directional sessions, such as Voice over IP and video conferencing. In this case, we propose two joint schemes, which are able to maximise the number of satisfied bi-directional sessions. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1363601 / Thesis (Ph.D.) -- University of Adelaide, School of Electrical and Electronic Engineering, 2009

El acelerado desarrollo de las tecnologías en telecomunicaciones tanto de telefonía fija y móvil como de las redes de datos, junto con el surgimiento de nuevas tecnologías de acceso para proveer distintos servicios han abierto las puertas a nuevos problemas y oportunidades a las empresas. Mientras por un lado, la amplia gama de tecnologías ha permitido un mayor número de servicios y de penetración en los distintos estratos y nichos de usuarios, por otro lado, la interoperabilidad entre distintas redes se ha vuelto un problema no menor. Desde hace algún tiempo se están viviendo una serie de cambios dentro de las redes de los operadores de telecomunicaciones: ya no basta que una empresa de telefonía ofrezca sólo servicios de telefonía e Internet, o que las empresas distribuidoras de televisión por cable ofrezcan sólo servicios de televisión, sino que todas las redes de telecomunicaciones se están orientando y evolucionando a brindar un amplio espectro de servicios. Este fenómeno se conoce como convergencia de redes o FMC (Fixed Mobile Convergence). El concepto de convergencia fija-móvil se enfoca a la provisión de servicios desde cualquier tipo de terminal y sin importar la red de acceso utilizada. Para eso es necesario hacer que todos los tipos de redes de telecomunicaciones interactúen entre sí, de forma de orientarlas a los servicios y aplicaciones sin importar la naturaleza del acceso utilizado por el usuario. Surgen así conceptos como el de NGN (Next Generation Network) para lograr este objetivo y nuevas arquitecturas integradoras como lo son IMS (IP Multimedia Subsystem). En este trabajo se presenta un estudio de las principales arquitecturas actuales de telefonía tanto fijas como móviles, donde se contempla la telefonía fija tradicional, celular e IP. Dentro de este estudio se examinan sus componentes funcionales, protocolos e interfaces con la finalidad de plantear y estudiar las arquitecturas y componentes necesarias para que estas redes sean interoperables, planteando una arquitectura convergente y orientada a servicios. Se expone como resultado principalmente un estudio de la arquitectura IMS como una opción factible para lograr la convergencia, mostrando sus principales entidades y procedimientos de interoperación con otras redes. Además, como un aporte a las tecnologías de acceso inalámbricas emergentes en servicios de redes se plantea una arquitectura con WiMAX como tecnología de acceso y se comparan sus ventajas y desventajas en relación a otras tecnologías de acceso a las redes de telecomunicaciones. La descripción detallada tanto de las componentes de IMS como paraguas de la convergencia como de los procedimientos de interoperación entre esta arquitectura y diferentes redes de acceso da pie para el desarrollo de nuevas memorias relativas a este tema, como por ejemplo la implementación de una arquitectura convergente a nivel docente basada en IMS utilizando tecnologías de acceso de interés en la actualidad, como lo son las tecnologías inalámbricas y en particular WiMAX. Las futuras investigaciones y trabajos de desarrollo basados en la convergencia de redes son de gran importancia en la formación de ingenieros útiles y valiosos para el mercado de hoy en día.

WiMAX provides broadband wireless access and uses OFDM as the underlying modulation technique. In an OFDM based wireless communication system, the channel will distort the transmitted signal and the performance is seriously degraded by synchronization mismatches between the transmitter and receiver. Therefore such systems require extensive digital signal processing of the received signal for retrieval of the transmitted information. In this master thesis, parts of an IEEE 802.16d (WiMAX) receiver have been implemented on a programmable baseband processor. The implemented parts constitute baseband algorithms which compensates for the effects from the channel and synchronization errors. The processor has a new innovative architecture with an instruction set optimized for baseband applications. This report includes theory behind the baseband algorithms as well as a presentation of how they are implemented on the processor. An impartial evaluation of the processor performance with respect to the algorithms used in the reference model is also presented in the report.

In this paper, an asymmetric compact multiband slot antenna is proposed for global positioning system (GPS), worldwide interoperability for microwave access (WiMAX), and wireless area network (WLAN) applications. The top plane, a ground is composed of a rectangular slot with a trapezoidal-like stub, an inverted U-shaped slot at the right side of the rectangular slot, an inverted L-shaped slot at the left side of the rectangular slot, and three stubs. The proposed antenna is fed by an asymmetric cross-parasitic strip on the bottom plane. By properly designing the slots and stubs, four resonant frequency bands are achieved with -10 dB reflection coefficient bandwidths of 50 MHz, 400 MHz, 390 MHz, and 830 MHz in the 1.57 GHz GPS band, 2.4 GHz WLAN band, 3.5 GHz WiMAX band, and 5.5 GHz WLAN bands, respectively. The antenna has a total compact size of 13 mm x 32 mm x 0.8 mm. Simulated and measured results indicate that the proposed antenna has sufficient bandwidth and good radiation performance in each band.

Modern wireless communication systems transmit complex modulated signals with high peak to average ratio in order to deliver high data rates. It demands wide bandwidth and rigorous efficiency performance for power amplifiers. Today’s conventional RF power amplifiers have relatively poor operating efficiency and require more power and area for operation. Therefore, more research on high efficiency power amplifier is crucial to the growth of the wireless industry. Until recent days, WiMAX systems are using technology processes such as Gallium Arsenide (GaAs) and Si LDMOSFET to obtain the performance. Although they are providing the required functional performance, they do not optimize cost and/or size. The primary focus of this thesis is to enhance the efficiency and output power of a compact microwave Power Amplifier suitable for a WiMAX base station. To achieve this goal, this thesis explores the highly efficient switched mode Class E microwave power amplifier using the Gallium Nitride on Silicon Carbide HFET (GaN-on-SiC) technology. The smallest gate length (0.15 µm) device recently released by NRC is used in this design. It provides higher performance at lower cost and area than the alternative Gallium Arsenide (GaAs) technology. Importance is given in designing the bias network of the device. The biasing network has a great impact on efficiency of power amplifiers. Many new techniques of Class E design have been presented to date, but there is not significant improvement related to the biasing network. A highly efficient Class E power amplifier for WiMAX base station transmitter was developed in this thesis for 2.5 GHz application. An improved bias network was introduced for biasing the active device. This successful design shows acceptable simulated performance with a gain of 10.12 dB, an output power of 34.12 dB, and a power added efficiency of 41.7 % at the peak output power.

The Worldwide Interoperability for Microwave Access, or WiMax, is a wireless communication technique based on IEEE 802.16 standards. Its advantage of sending high data rates over long distances, while using a single base station to cover a large area, has made this technique a flexible and reliable solution for public wireless networks. WiMax has two main types of networks: Fixed and Mobile. The most popular transceiver used in WiMax applications is the “Direct-Conversion Architecture” due to its high level of integration and less component requirements, which leads to reduced power dissipation. In Direct Conversion Architecture, the mixer is a key block in the transceiver chain. Depending on design specifications and constraints, different types of mixers may be considered. However, the most appropriate down converter mixer for WiMax applications is the Gilbert-cell mixer. This thesis will then explore the design of a down converter Gilbert-Cell Mixer within the realm of Fixed WiMax technology. This design was achieved in the commercial circuit simulator Advanced Design System (ADS) using the 0.15mm InGaAs pHEMT technology process provided by Win Semiconductor Crop.

No / This paper proposes a tuneable band-rejected miniaturised monopole antenna. The band-notching was achieved by printing an inner chorded crescent shape over the surface of the substrate. By placing a small varactor between the inner and outer arches, the centre frequency of each notch can be individually shifted downwards. The design of the proposed structure has a controllable rejection in the range from 2.38 to 3.87 GHz maintaining a wideband performance from 1.5 to 5 GHz based on VSWR ≤ 2. The antenna prototype was fabricated and tested. Simulated and measured results are performed and analysed. With a compact size, the proposed monopole antenna may well work as an internal antenna in a portable device.

Avec l’évolution rapide des technologies réseaux et télécoms radios mobiles, les chercheurs sont actuellement en train de préparer l’arrivée d’une nouvelle génération baptisée 4G. Le réseau de 4ème génération qui est encore l’objet de travaux de recherche vise à améliorer l’efficacité spectrale et à augmenter la capacité de gestion du nombre des mobiles dans une même cellule. Il tend à offrir des débits élevés en situation de mobilité à grande ou faible vitesse. Il vise aussi à permettre et à faciliter l’interconnexion et l’interopérabilité entre différentes technologies existantes en rendant transparent à l’utilisateur le passage entre les réseaux. Enfin, il vise à éviter l’interruption des services durant le transfert intercellulaire, et à basculer l’utilisation vers le tout IP. Dans ce contexte, nous nous sommes intéressés en premier lieu aux problématiques de la QoS en situation de mobilité au sein d’une technologie candidate à la 4G (WiMAX mobile) pour du trafic temps-réel. Pour cela, nous avons comparé la performance de plusieurs protocoles de mobilité dans le contexte du Handover de niveau 2 et de niveau 3 et plus. Nous avons pour cela fait varier les modèles de mobilité, les configurations et les scénarios. Enfin, nous avons modélisé un algorithme décisionnel qui gère le Handover dans le WiMAX mobile en fonction de plusieurs paramètres d’entrées. Au travers de ces études, nous avons dégagé des protocoles de mobilité qui offrent un niveau de QoS acceptable pour un trafic temps-réel dans le cadre des scénarios envisagés. En deuxième lieu, nous nous sommes concentrés sur les problèmes d’interconnexion et d’interopérabilité entre les réseaux en tenant compte de la mobilité et du Handover vertical entre deux technologies. Pour cela, nous avons proposé de comparer des protocoles de mobilité puis de les combiner afin de diminuer les délais des trafics temps-réel au cours du Handover. Au niveau de l’interconnexion, nous avons proposé des modèles entre WiMAX mobile et de nombreux autres standards (802.11e, UMTS, DVB-S/RCS, LTE). Outre les solutions d’interconnexion, nous avons également mis en évidence la ou les combinaisons de protocoles de gestion de la mobilité qui permettent de garantir de la QoS. / With the rapid evolution of mobile radio telecommunications and networks technologies, researchers are currently preparing the arrival of a new generation called 4G. The 4th generation network aims to improve spectral efficiency and increase capacity to manage a large number of mobiles in a cell. It tries to provide high flow rates under high or low mobility. It also aims to enable and facilitate the interconnection and the interoperability between different technologies allowing transparent transition between networks. Finally, it aims to avoid interruption of services during the handover, and to switch an all-IP system. In this context, we are concerned first with QoS and mobility issues in Mobile WiMAX for the real-time traffic. We compared the performance of several mobility protocols in the context of the level 2 and level 3+ handovers. Several mobility models, configurations and scenarios were considered. Finally, we modeled a decision algorithm that manages the handover in mobile WiMAX based on several input parameters.Through these studies, we have identified mobility protocols that provide an acceptable QoS level for real-time traffic under the proposed scenarios. Secondly, we focused on the problems of interconnection and interoperability between networks, taking into account the mobility and vertical handovers between two technologies. For this, we proposed to compare mobility protocols or combine them to reduce delays for real-time traffic during the handover. We also proposed interconnection models between mobile WiMAX and many other standards (802.11e, UMTS, DVB-S/RCS, LTE). Besides interconnection solutions, we also highlighted the combination or combinations of management mobility protocols that can guarantee QoS.

[pt] O WiMAX é um padrão de tecnológico de broadband wireless que tem o potencial de oferecer infra-estrutura para conectividade de última milha para clientes corporativos e residências, abrangendo grandes distâncias e oferecendo uma alternativa ao DSL e cabo. Este novo padrão wireless é percebido pelas empresas de telecomunicações como uma oportunidade de ganhar penetração em localidades onde ainda não são oferecidas soluções de banda larga. Como qualquer padrão wireless, o WiMAX necessita de faixas de espectros de freqüência para operar, e como as faixas de freqüências são bens públicos e escassos, as mesmas são licitadas pelo órgão regulador garantindo exclusividade no seu uso. Este trabalho avalia quanto uma empresa pode ofertar numa licitação de blocos de freqüência na faixa de 3,5GHz que serão utilizados para operar um rede WiMAX tanto pelo método tradicional do FCD quanto pela teoria das opções reais. No mercado de telecomunicações, este tipo de projeto apresenta grandes incertezas e também significativas flexibilidades gerenciais, o que indica que a teoria de opções reais pode ser mais adequada para este tipo de análise. Os resultados obtidos conferem isso e as opções do projeto aumentaram seu valor em 149%, permitindo à empresa elevar o valor máximo a ser ofertado na licitação em até 58% do valor original obtido pelo FCD, aumentando as chances de vencer a licitação e investir em um projeto rentável. / [en] WiMAX is a broadband wireless technology developed as an alternative to DSL and cable, to offer infrastructure last mile connectivity for business and residential clients, covering great distance. This new wireless standard is considered in telecommunication marketing as an opportunity to offer broadband in areas where this service does not exist. As any wireless standard, WiMAX requires spectrum allocations to operate, and as frequency bands are scarce public assets, they are bid out by the regulatory agency to assure exclusivity. In this dissertation we value the bid for some frequency bands of the 3,5GHz WiMAX frequency spectrum, under both Discounted Cash Flow methods (DCF) and Real Option Valuation. In the telecommunications market, this type of project presents great uncertainty and flexibility, which implies that real option valuation is the best alternative for this analysis. The results shows that the options embedded in the project increase its value by up to 149% when compared to the DCF approach. This allows the firm to increase the value of its bid by up to 58%, increasing its chances of wining a profitable project.

Made available in DSpace on 2016-04-04T18:31:23Z (GMT). No. of bitstreams: 1 FRANCISCO JOSE LOPES RODOVALHO.pdf: 13305799 bytes, checksum: 23374e97fb38c10170518a8f35e72196 (MD5) Previous issue date: 2008-05-29 / This work brings as hypothesis the possibility of the development of a method capable to evaluate WMAN s equipments in terms of coverage and performance, portrayed through its efficiency, focused on WiMAX technology, pattern IEEE 802.16-2004. The objective is to present the procedures to make possible to use a test site to compare the acting of different manufacturers' equipments. It begins with a site where its physical and propagation parameters are obtained, always the same for those certain points, to compare the performance of several equipments through reference measures in terms of the data rate efficiency. The site is characterized through 51 measure points. The tools used and developed for the test accomplishment are also described. Such tools are, for example, the coverage prediction software CellPlanner and a software tool, called GetMIB developed to capture, through the SNMP commands, the stored data in MIBs, and a script for tasks automation by the free software AutoiT. The test results presented the Signal-to-Noise-Relation (SNR), the values of BETA (?), which represents the path loss exponent, the Instantaneous and Accumulated Efficiencies of data rate net communication, as well as the correlation between these obtained variables, which have been presented in graphs and tables. The proposed method has proved to be reliable once it has presented suitable results with the performance expectation of the equipment and is in accordance with the environment used in the tests. From the results verified for the tested equipment, its replacement by other equipments of several manufacturers can be conceived, with similar results. From the confrontation of these results it is possible to obtain information on which equipment better adapts to those operation conditions imposed by the site. / Este trabalho traz como hip?tese a possibilidade do desenvolvimento de um m?todo capaz de avaliar equipamentos de uma WMAN em termos de cobertura e desempenho, retratado atrav?s de sua efici?ncia, voltada para a tecnologia WiMAX, padr?o IEEE 802.16-2004. O objetivo ? apresentar os procedimentos que possibilitem utilizar um site de testes, para comparar o desempenho de equipamentos de diferentes fabricantes. Parte-se de um site, onde se obtenham os par?metros f?sicos e de propaga??o do mesmo, sempre iguais para aqueles pontos determinados, comparar o desempenho de equipamentos diversos atrav?s de medidas de refer?ncia, em termos da efici?ncia da taxa de dados. O site fica caracterizado atrav?s de 51 pontos de medida. S?o tamb?m descritas as ferramentas utilizadas e desenvolvidas para a realiza??o dos testes, tais como o software de predi??o de cobertura CellPlanner, uma ferramenta de software chamado de GetMIB desenvolvido para capturar, via SNMP, os dados armazenados nas MIBs, e um script atrav?s do sofware livre AutoiT para automatiza??o das tarefas. Os resultados dos testes realizados apresentaram a Rela??o Sinal Ru?do (SNR), os valores de BETA (?), que representa o expoente de perda de percurso, as Efici?ncias Instant?nea e Acumulada da rede de comunica??o de dados, bem como a correla??o entre estas vari?veis obtidas, as quais foram apresentadas de forma gr?fica e tabeladas. O m?todo proposto se mostrou confi?vel uma vez que apresentou resultados condizentes com a expectativa de desempenho do equipamento e em conformidade com o ambiente utilizado nos testes. A partir dos resultados verificados para o equipamento testado, pode-se conceber a sua substitui??o por outros equipamentos de fabricantes diversos, obtendo-se resultados similares. Da confronta??o destes resultados ? poss?vel obter-se informa??es sobre qual equipamento melhor se adapta ?quelas condi??es de opera??o impostas pelo site.