339 research outputs found
Building Programmable Wireless Networks: An Architectural Survey
In recent times, there have been a lot of efforts for improving the ossified
Internet architecture in a bid to sustain unstinted growth and innovation. A
major reason for the perceived architectural ossification is the lack of
ability to program the network as a system. This situation has resulted partly
from historical decisions in the original Internet design which emphasized
decentralized network operations through co-located data and control planes on
each network device. The situation for wireless networks is no different
resulting in a lot of complexity and a plethora of largely incompatible
wireless technologies. The emergence of "programmable wireless networks", that
allow greater flexibility, ease of management and configurability, is a step in
the right direction to overcome the aforementioned shortcomings of the wireless
networks. In this paper, we provide a broad overview of the architectures
proposed in literature for building programmable wireless networks focusing
primarily on three popular techniques, i.e., software defined networks,
cognitive radio networks, and virtualized networks. This survey is a
self-contained tutorial on these techniques and its applications. We also
discuss the opportunities and challenges in building next-generation
programmable wireless networks and identify open research issues and future
research directions.Comment: 19 page
Integrated Architecture for Configuration and Service Management in MANET Environments
Esta tesis nos ha permitido trasladar algunos conceptos teóricos de la computación ubicua a escenarios reales, identificando las necesidades específicas de diferentes tipos de aplicaciones. Con el fin de alcanzar este objetivo, proponemos dos prototipos que proporcionan servicios sensibles al contexto en diferentes entornos, tales como conferencias o salas de recuperación en hospitales. Estos prototipos experimentales explotan la tecnología Bluetooth para ofrecer información basada en las preferencias del usuario. En ambos casos, hemos llevado a cabo algunos experimentos con el fin de evaluar el comportamiento de los sistemas y su rendimento.
También abordamos en esta tesis el problema de la autoconfiguración de redes MANET basadas en el estándar 802.11 a través de dos soluciones novedosas. La primera es una solución centralizada que se basa en la tecnología Bluetooth, mientras la segunda es una solución distribuida que no necesita recurrir a ninguna tecnología adicional, ya que se basa en el uso del parámetro SSID. Ambos métodos se han diseñado para permitir que usuarios no expertos puedan unirse a una red MANET de forma transparente, proporcionando una configuración automática, rápida, y fiable de los terminales. Los resultados experimentales en implementaciones reales nos han permitido evaluar el rendimiento de las soluciones propuestas y demostrar que las estaciones cercanas se pueden configurar en pocos segundos. Además, hemos comparado ambas soluciones entre sí para poner de manifiesto las diferentes ventajas y desventajas en cuanto a rendimento.
La principal contribución de esta tesis es EasyMANET, una plataforma ampliable y configurable cuyo objetivo es automatizar lo máximo posible las tareas que afectan a la configuración y puesta en marcha de redes MANET, de modo que su uso sea más simple y accesible.Cano Reyes, J. (2012). Integrated Architecture for Configuration and Service Management in MANET Environments [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/14675Palanci
Beacon scheduling in cluster-tree IEEE 802.15.4/ZigBee wireless sensor networks
The recently standardized IEEE 802.15.4/Zigbee protocol stack offers great potentials for ubiquitous and
pervasive computing, namely for Wireless Sensor Networks (WSNs). However, there are still some open and
ambiguous issues that turn its practical use a challenging task. One of those issues is how to build a
synchronized multi-hop cluster-tree network, which is quite suitable for QoS support in WSNs. In fact, the
current IEEE 802.15.4/Zigbee specifications restrict the synchronization in the beacon-enabled mode (by the
generation of periodic beacon frames) to star-based networks, while it supports multi-hop networking using
the peer-to-peer mesh topology, but with no synchronization. Even though both specifications mention the
possible use of cluster-tree topologies, which combine multi-hop and synchronization features, the
description on how to effectively construct such a network topology is missing. This report tackles this
problem, unveils the ambiguities regarding the use of the cluster-tree topology and proposes two collisionfree
beacon frame scheduling schemes
On the use of the ZigBee protocol for wireless sensor networks
This project was developed within the ART-WiSe framework of the IPP-HURRAY group
(http://www.hurray.isep.ipp.pt), at the Polytechnic Institute of Porto (http://www.ipp.pt).
The ART-WiSe – Architecture for Real-Time communications in Wireless Sensor networks – framework
(http://www.hurray.isep.ipp.pt/art-wise) aims at providing new communication architectures and
mechanisms to improve the timing performance of Wireless Sensor Networks (WSNs). The architecture is
based on a two-tiered protocol structure, relying on existing standard communication protocols, namely
IEEE 802.15.4 (Physical and Data Link Layers) and ZigBee (Network and Application Layers) for Tier 1
and IEEE 802.11 for Tier 2, which serves as a high-speed backbone for Tier 1 without energy consumption
restrictions.
Within this trend, an application test-bed is being developed with the objectives of implementing, assessing
and validating the ART-WiSe architecture. Particularly for the ZigBee protocol case; even though there is a
strong commercial lobby from the ZigBee Alliance (http://www.zigbee.org), there is neither an open source
available to the community for this moment nor publications on its adequateness for larger-scale WSN
applications. This project aims at fulfilling these gaps by providing: a deep analysis of the ZigBee
Specification, mainly addressing the Network Layer and particularly its routing mechanisms; an
identification of the ambiguities and open issues existent in the ZigBee protocol standard; the proposal of
solutions to the previously referred problems; an implementation of a subset of the ZigBee Network Layer,
namely the association procedure and the tree routing on our technological platform (MICAz motes, TinyOS
operating system and nesC programming language) and an experimental evaluation of that routing
mechanism for WSNs
IEEE 802.15.4 for wireless sensor networks: a technical overview
Low-rate low-power consumption and low-cost
communication are the key points that lead to the specification of
the IEEE 802.15.4 standard. This paper overviews the technical
features of the physical layer and the medium access control sublayer
mechanisms of the IEEE 802.15.4 protocol that are most
relevant for wireless sensor network applications. We also
discuss the ability of IEEE 802.15.4 to fulfil the requirements of
wireless sensor network applications
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