PACE: Simple Multi-hop Scheduling for Single-radio 802.11-based Stub Wireless Mesh Networks

IEEE 802.11-based Stub Wireless Mesh Networks (WMNs) are a cost-effective and flexible solution to extend wired network infrastructures. Yet, they suffer from two major problems: inefficiency and unfairness. A number of approaches have been proposed to tackle these problems, but they are too restrictive, highly complex, or require time synchronization and modifications to the IEEE 802.11 MAC. PACE is a simple multi-hop scheduling mechanism for Stub WMNs overlaid on the IEEE 802.11 MAC that jointly addresses the inefficiency and unfairness problems. It limits transmissions to a single mesh node at each time and ensures that each node has the opportunity to transmit a packet in each network-wide transmission round. Simulation results demonstrate that PACE can achieve optimal network capacity utilization and greatly outperforms state of the art CSMA/CA-based solutions as far as goodput, delay, and fairness are concerned

Ethernet - a survey on its fields of application

During the last decades, Ethernet progressively became the most widely used local area networking (LAN) technology. Apart from LAN installations, Ethernet became also attractive for many other fields of application, ranging from industry to avionics, telecommunication, and multimedia. The expanded application of this technology is mainly due to its significant assets like reduced cost, backward-compatibility, flexibility, and expandability. However, this new trend raises some problems concerning the services of the protocol and the requirements for each application. Therefore, specific adaptations prove essential to integrate this communication technology in each field of application. Our primary objective is to show how Ethernet has been enhanced to comply with the specific requirements of several application fields, particularly in transport, embedded and multimedia contexts. The paper first describes the common Ethernet LAN technology and highlights its main features. It reviews the most important specific Ethernet versions with respect to each application field’s requirements. Finally, we compare these different fields of application and we particularly focus on the fundamental concepts and the quality of service capabilities of each proposal

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

Mestrado em Engenharia Electrónica e TelecomunicaçõesA indústria das telecomunicações tem sofrido uma evolução enorme nosúltimos anos. Tanto em termos de comunicações sem fios, como em termos deligações de banda larga, assistiu-se a uma adesão massiva por parte domercado, o que se traduziu num crescimento enorme, já que a tecnologia temque estar um passo à frente da procura, de forma a suprir as carências 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 à banda larga sem fios depróxima geração. De seguida, apresenta testes efectuados com osequipamentos disponíveis de WiMAX e WI-FI em Malha, de forma a mostrar ocorrecto comportamento da atribuição extremo-a-extremo de QoS nos cenáriosescolhidos 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

ABridges: Scalable, self-configuring Ethernet campus networks

This article describes a scalable, self-configuring architecture for campus networks, the ABridges architecture. It is a two-tiered hierarchy of layer two switches in which network islands running independent rapid spanning tree protocols communicate through a core formed by island root bridges (ABridges). ABridges use AMSTP, a simplified and self configuring version of MSTP protocol, to establish shortest paths in the core using multiple spanning tree instances, one instance rooted at each core edge ABridge. The architecture is very efficient in terms of network usage and path length due to the ability of AMSTP to provide optimum paths in the core mesh, while RSTP is used to aggregate efficiently the traffic at islands networks, where sparsely connected, tree-like topologies are frequent and recommended. Convergence speed is as fast as existing Rapid Spanning Tree and Multiple Spanning Tree Protocols.Publicad

Interworking and Cross-layer Service Discovery Extensions for IEEE 802.11s Wireless Mesh Standard, Journal of Telecommunications and Information Technology, 2013, nr 3

With the rapid popularization of mobile end-user electronic devices, wireless network technologies begin to play a crucial role as networks access technologies. While classic point-to-multipoint wireless access systems, based on fixed infrastructure of base stations providing access to clients, remain the main most popular solution, an increasing attention is devoted to wireless mesh systems, where each connecting client can extend overall resources of the network by becoming a network node capable of forwarding transit traffic. This ability results in severe reduction of the necessary network infrastructure, provides through coverage (thereby offering significant step towards ubiquity of network access) and offers massive redundancy. One of the most promising wireless mesh solutions currently being developed is an IEEE 802.11s standard, based on popular Wi-Fi technology. It combines low deployment costs with comprehensive suite of mechanisms able to operate a self-forming, autoconfigurable, dynamically extending, and secure mesh solution. However, despite its advantages, the standard lacks sufficient support for a number of functionalities, which can lead to significant inefficiency and degradation of service quality in real-world IEEE 802.11s network deployments. In the paper we propose a number of extensions of IEEE 802.11s mechanisms, designed to provide better service quality in case of real-world deployment scenarios, especially in case of large systems. Both propositions introduce modifications to mesh path discovery and interworking procedures, while retaining compatibility with standard solution. Their basic functionality and efficiency have been verified by means of simulation model in large-scale, self-organizing mesh structure. Subsequently they have been implemented and tested in real-world, access network testbed deployment. The results clearly indicate their utility, particularly in case of larger deployments of this network system type

An enhanced bridged-based multi-hop wireless network implementation

Proceedings of: 5th Annual ICST Wireless Internet Conference (WICON 2010), 1-3 March 2010, SingaporeIn this paper an enhanced Layer-2 multi-hop wireless network implementation for Infrastructure based Wireless Mesh Networks is presented. This work combines the flexibility of Layer-2 Wireless Bridging with the dynamic self-configuring capabilities of MANET routing. The main contribution of this paper is an investigation of the issues encountered when applying a pure bridging based solution to wireless multi-hop networks and the development of several mechanisms to overcome these problems. This work was implemented and deployed in a real testbed environment using Routerboard hardware and utilising a number of open-source network tools in accordance with the needs of our platform. The developed testbed incorporates self-healing and self-configuration features without requiring a traditional MANET routing protocol. Instead the 802.11 beacon frames sent by the Access Points were extended with link information to allow optimal construction of the mesh topology. Results are presented which demonstrate the automated topology construction mechanism. Further results also show the enhancements made to the normal 802.11 Layer-2 mobility mechanism.European Community's Seventh Framework ProgramPublicad

Difusão eficiente de tráfego multicast em redes emalhadas 802.11 com suporte de mobilidade

Tese de mestrado integrado. Engenharia Electrotécnica e de Computadores (Major Telecomunicações). Faculdade de Engenharia. Universidade do Porto. 201