71 research outputs found

    A Survey on Scheduling in IEEE 802.16 Mesh Mode

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    Cataloged from PDF version of article.IEEE 802.16 standard (also known as WiMAX) defines the wireless broadband network technology which aims to solve the so called last mile problem via providing high bandwidth Internet even to the rural areas for which the cable deployment is very costly. The standard mainly focuses on the MAC and PHY layer issues, supporting two transmission modes: PMP (Point-to-Multipoint) and mesh modes. Mesh mode is an optional mode developed as an extension to PMP mode and it has the advantage of having an improving performance as more subscribers are added to the system using multi-hop routes. In 802.16 MAC protocol, mesh mode slot allocation and reservation mechanisms are left open which makes this topic a hot research area. Hence, the focus of this survey will mostly be on the mesh mode, and the proposed scheduling algorithms and performance evaluation methods

    Experimental analysis of WiMAX and meshed Wi-Fi quality of service

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    Mestrado em Engenharia ElectrĂłnica e TelecomunicaçÔesA indĂșstria das telecomunicaçÔes tem sofrido uma evolução enorme nosĂșltimos anos. Tanto em termos de comunicaçÔes sem fios, como em termos deligaçÔes de banda larga, assistiu-se a uma adesĂŁo massiva por parte domercado, o que se traduziu num crescimento enorme, jĂĄ que a tecnologia temque estar um passo Ă  frente da procura, de forma a suprir as carĂȘncias dosconsumidores. Assim, a evolução persegue um objectivo claro: possibilidadede possuir conectividade de banda larga em qualquer lugar e instante. Nestecontexto, aparecem as tecnologias WiMAX (Worldwide Interoperability forMicrowave Access) e WI-FI em Malha como possibilidades para atingir estefim. O tema desta dissertação incide no estudo das tecnologias de WiMAX e WI-FIem Malha, mais concretamente no estudo da Qualidade de Serviço (QoS)providenciada pelas normas IEEE 802.16 e IEEE 802.11s para serviços deVoIP e VoD. Esta tese apresenta a arquitectura desenvolvida para a correcta integração deQoS para serviços em tempo real no acesso Ă  banda larga sem fios deprĂłxima geração. De seguida, apresenta testes efectuados com osequipamentos disponĂ­veis de WiMAX e WI-FI em Malha, de forma a mostrar ocorrecto comportamento da atribuição extremo-a-extremo de QoS nos cenĂĄriosescolhidos com serviços em tempo real, bem como os efeitos da mobilidade natecnologia WI-FI em Malha. ABSTRACT: The telecommunication industry has suffered a massive evolution throughoutpast years. In terms of wireless communications, as well as broadbandconnections, we’ve seen a massive adoption by the market, which conductedinto an enormous growth, since the technology must always be one step aheadof the demand, in order to be to fulfill the needs of the consumers. Therefore,the evolution pursues one clear goal: the possibility to establish a broadbandconnection anywhere and anytime. In this context, the WiMAX (WorldwideInteroperability for Microwave Access) and Meshed WI-FI technologies appearas possibilities to reach this goal. The subject of this thesis is the study of both the WiMAX and Meshed WI-FItechnologies, and more concretely the study of the QoS provided by theIEEE802.16 and IEEE 802.11s standards to VoIP and VoD services. This thesis presents the architecture developed to provide the correctintegration of QoS for real-media traffic in next generation broadband wirelessaccess. It presents tests carried out with the available WiMAX and Meshed WI-FI equipments, to show the correct behavior in the attribution of end-to-endQoS in selected scenarios with real-time services, as well as mobility effects onWI-FI Wireless Mesh technology

    Energy efficiency in next generation wireless networks: methodologies, solutions and algorithms

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    Mobile Broadband Wireless Access (BWA) networks will offer in the forthcoming years multiple and differentiated services to users with high mobility requirements, connecting via portable or wearable devices which rely on the use of batteries by necessity. Since such devices consume a relatively large fraction of energy for transmitting/receiving data over-the-air, mechanisms are needed to reduce power consumption, in order to increase the lifetime of devices and hence improve user’s satisfaction. Next generation wireless network standards define power saving functions at the Medium Access Control (MAC) layer, which allow user terminals to switch off the radio transceiver during open traffic sessions for greatest energy consumption reduction. However, enabling power saving usually increases the transmission latency, which can negatively affect the Quality of Service (QoS) experienced by users. On the other hand, imposing stringent QoS requirements may limit the amount of energy that can be saved. The IEEE 802.16e standard defines the sleep mode is power saving mechanism with the purpose of reducing energy consumption. Three different operation classes are provided, each one to serve different class of traffic: class I, best effort traffic, class II real time traffic and class III multicast traffic. Several aspects of the sleep mode are left unspecified, as it is usually done in standards, allowing manufacturers to implement their own proprietary solutions, thus gaining a competitive advantage over the rivals. The work of this thesis is aimed at verifying, the effectiveness of the power saving mechanism proposed into IEEE 802.16e standard, focusing on the mutual interaction between power saving and QoS support. Two types of delay constrained applications with different requirements are considered, i.e., Web and Voice over IP (VoIP). The performance is assessed via detailed packet-level simulation, with respect to several system parameters. To capture the relative contribution of all the factors on the energy- and QoS-related metrics, part of the evaluation is carried out by means of 2k · r! analysis. Our study shows that the sleep mode can achieve significant power consumption reduction, however, when real time traffic is considered a wise configuration of the parameters is mandatory in order to avoid unacceptable degradation of the QoS. Finally, based on the guidelines drawn through the analysis, we extend our contribution beyond a simple evaluation, proposing a power saving aware scheduling framework aimed at reducing further the energy consumption. Our framework integrates with existing scheduling policies that can pursue their original goals, e.g. maximizing throughput or fairness, while improving the energy efficiency of the user terminals. Its effectiveness is assessed through an extensive packet level simulation campaign

    Wireless Technologies for IoT in Smart Cities

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    [EN] As cities continue to grow, numerous initiatives for Smart Cities are being conducted. The concept of Smart City encompasses several concepts being governance, economy, management, infrastructure, technology and people. This means that a Smart City can have different communication needs. Wireless technologies such as WiFi, ZigBee, Bluetooth, WiMax, 4G or LTE (Long Term Evolution) have presented themselves as solutions to the communication needs of Smart City initiatives. However, as most of them employ unlicensed bands, interference and coexistence problems are increasing. In this paper, the wireless technologies available nowadays for IoT (Internet of Things) in Smart Cities are presented. Our contribution is a review of wireless technologies, their comparison and the problems that difficult coexistence among them. In order to do so, the characteristics and adequacy of wireless technologies to each domain are considered. The problems derived of over-crowded unlicensed spectrum and coexistence difficulties among each technology are discussed as well. Finally, power consumption concerns are addressed.GarcĂ­a-GarcĂ­a, L.; Jimenez, JM.; Abdullah, MTA.; Lloret, J. (2018). Wireless Technologies for IoT in Smart Cities. Network Protocols and Algorithms. 10(1):23-64. doi:10.5296/npa.v10i1.12798S236410

    On Cloud-based multisource Reliable Multicast Transport in Broadband Multimedia Satellite Networks

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    Multimedia synchronization, Software Over the Air, Personal Information Management on Cloud networks require new reliable protocols, which reduce the traffic load in the core and edge network. This work shows via simulations the performance of an efficient multicast file delivery, which advantage of the distributed file storage in Cloud computing. The performance evaluation focuses on the case of a personal satellite equipment with error prone channels

    Analysis of SoftToken: a coordinated Medium Access Control (MAC) for IEEE 802.11 based wireless mesh networks

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    Wireless Mesh Networks (WMNs) which can be integrated to other types of networks at a reasonable cost are good candidates to facilitate the efficient and flexible deployment of Next Generation Networks (NGNs). Due to the widespread presence of IEEE 802.11Wireless Local Area Networks (WLANs) most of current WMNs are based on this technology. However, IEEE 802.11 is primarly designed for one-hop networks and its random access protocol (CSMA/CA) is problematic in multi-hop environments due to collisions, which decrease efficiency and service quality. To alleviate these problems a novel approach, SoftToken, was proposed to provide a coordinated Medium Access Control (MAC) for WLANs whose goal is to add a token-passing mechanism on top of the standard IEEE 802.11 in a way that collisions can be avoided. In this thesis, we present an analysis and evaluation of SoftToken in various scenarios. We also develop some functions to integrate this protocol into the architecture designed by the CARrier grade MEsh Networks (CARMEN) project. -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------Las Redes de Malla Inalåmbricas (WMN en inglés) permiten integrar a un coste razonable otros tipos de redes, haciendo de ellas las candidatas idóneas para facilitar el despliegue eficiente y flexible de Redes de Siguiente Generación (NGN en inglés). La amplia presencia de las Redes de Area Local Inalåmbricas (WLAN en inglés) basadas en el eståndar IEEE 802.11 explica el que la mayoría de las WMNs actualmente desplegadas estén basadas en dicho eståndar. Sin embargo, la naturaleza distribuida de IEEE 802.11 crea problemas en las redes multisalto debido al mecanismo de acceso al medio utilizado (CSMA/CA) que genera colisiones disminuyendo la eficiencia y la calidad del servicio. En este Proyecto Fin de Carrera, presentamos el anålisis del rendimiento de SoftToken, que propone un novedoso Mecanismo de Acceso al Medio (MAC en inglés) coordinado, basado en el principio del token o testigo. El objetivo de SoftToken consiste en añadir un mecanismo de paso de testigo por encima del eståndar IEEE 802.11 que evite las colisiones. También se han implementado algunas funciones para integrar este protocolo en la arquitectura diseñada por el proyecto CARMEN (CARrier grade MEsh Networks).Ingeniería de Telecomunicació

    Acesso banda larga sem fios em ambientes heterogéneos de próxima geração

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    Doutoramento em Engenharia InformĂĄticaO acesso ubĂ­quo Ă  Internet Ă© um dos principais desafios para os operadores de telecomunicaçÔes na prĂłxima dĂ©cada. O nĂșmero de utilizadores da Internet estĂĄ a crescer exponencialmente e o paradigma de acesso "always connected, anytime, anywhere" Ă© um requisito fundamental para as redes mĂłveis de prĂłxima geração. A tecnologia WiMAX, juntamente com o LTE, foi recentemente reconhecida pelo ITU como uma das tecnologias de acesso compatĂ­veis com os requisitos do 4G. Ainda assim, esta tecnologia de acesso nĂŁo estĂĄ completamente preparada para ambientes de prĂłxima geração, principalmente devido Ă  falta de mecanismos de cross-layer para integração de QoS e mobilidade. Adicionalmente, para alĂ©m das tecnologias WiMAX e LTE, as tecnologias de acesso rĂĄdio UMTS/HSPA e Wi-Fi continuarĂŁo a ter um impacto significativo nas comunicaçÔes mĂłveis durante os prĂłximos anos. Deste modo, Ă© fundamental garantir a coexistĂȘncia das vĂĄrias tecnologias de acesso rĂĄdio em termos de QoS e mobilidade, permitindo assim a entrega de serviços multimĂ©dia de tempo real em redes mĂłveis. Para garantir a entrega de serviços multimĂ©dia a utilizadores WiMAX, esta Tese propĂ”e um gestor cross-layer WiMAX integrado com uma arquitectura de QoS fim-a-fim. A arquitectura apresentada permite o controlo de QoS e a comunicação bidireccional entre o sistema WiMAX e as entidades das camadas superiores. Para alĂ©m disso, o gestor de cross-layer proposto Ă© estendido com eventos e comandos genĂ©ricos e independentes da tecnologia para optimizar os procedimentos de mobilidade em ambientes WiMAX. Foram realizados testes para avaliar o desempenho dos procedimentos de QoS e mobilidade da arquitectura WiMAX definida, demonstrando que esta Ă© perfeitamente capaz de entregar serviços de tempo real sem introduzir custos excessivos na rede. No seguimento das extensĂ”es de QoS e mobilidade apresentadas para a tecnologia WiMAX, o Ăąmbito desta Tese foi alargado para ambientes de acesso sem-fios heterogĂ©neos. Neste sentido, Ă© proposta uma arquitectura de mobilidade transparente com suporte de QoS para redes de acesso multitecnologia. A arquitectura apresentada integra uma versĂŁo estendida do IEEE 802.21 com suporte de QoS, bem como um gestor de mobilidade avançado integrado com os protocolos de gestĂŁo de mobilidade do nĂ­vel IP. Finalmente, para completar o trabalho desenvolvido no Ăąmbito desta Tese, Ă© proposta uma extensĂŁo aos procedimentos de decisĂŁo de mobilidade em ambientes heterogĂ©neos para incorporar a informação de contexto da rede e do terminal. Para validar e avaliar as optimizaçÔes propostas, foram desenvolvidos testes de desempenho num demonstrador inter-tecnologia, composta pelas redes de acesso WiMAX, Wi-Fi e UMTS/HSPA.Ubiquitous Internet access is one of the main challenges for the telecommunications industry in the next decade. The number of users accessing the Internet is growing exponentially and the network access paradigm of “always connected, anytime, anywhere” is a central requirement for the so-called Next Generation Mobile Networks (NGMN). WiMAX, together with LTE, was recently recognized by ITU as one of the compliant access technologies for 4G. Nevertheless, WiMAX is not yet fully prepared for next generation environments, mainly due to the lack of QoS and mobility crosslayer procedures to support real-time multimedia services delivery. Furthermore, besides the 4G compliant WiMAX and LTE radio access technologies, UMTS/HSPA and Wi-Fi will also have a significant impact in the mobile communications during the next years. Therefore, it is fundamental to ensure the coexistence of multiple radio access technologies in what QoS and mobility procedures are concerned, thereby allowing the delivery of real-time services in mobile networks. In order to provide the WiMAX mobile users with the demanded multimedia services, it is proposed in this Thesis a WiMAX cross-layer manager integrated in an end-to-end all-IP QoS enabled architecture. The presented framework enables the QoS control and bidirectional communication between WiMAX and the upper layer network entities. Furthermore, the proposed cross-layer framework is extended with media independent events and commands to optimize the mobility procedures in WiMAX environments. Tests were made to evaluate the QoS and mobility performance of the defined architecture, demonstrating that it is perfectly capable of handling and supporting real time services without introducing an excessive cost in the network. Following the QoS and mobility extensions provided for WiMAX, the scope of this Thesis is broaden and a seamless mobility architecture with QoS support in heterogeneous wireless access environments is proposed. The presented architecture integrates an extended version of the IEEE 802.21 framework with QoS support, as well as an advanced mobility manager integrated with the IP level mobility management protocols. Finally, to complete the work within the framework of this Thesis, it is proposed an extension to the handover decisionmaking processes in heterogeneous access environments through the integration of context information from both the network entities and the enduser. Performance tests were developed in a real testbed to validate the proposed optimizations in an inter-technology handover scenario involving WiMAX, Wi-Fi and UMTS/HSPA
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