685 research outputs found
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Selection of EAP-authentication methods in WLANs
IEEE 802.1X is a key part of IEEE802.11i. By employing Extensible Authentication Protocol (EAP) it supports a variety of upper layer
authentication methods each with different benefits and drawbacks. Any one of these authentication methods can be the ideal choice for a specific networking environment. The fact that IEEE 802.11i leaves the selection of the most suitable authentication method to system implementers makes the authentication framework more flexible, but on the other hand leads to the
question of how to select the authentication method that suits an organisation’s requirements and specific networking environment. This paper gives an overview of EAP authentication methods and provides a table comparing their properties. It then identifies the crucial factors to be considered when employing EAP authentication methods in WLAN environments. The paper presents algorithms that guide the selection of an EAP-authentication method for a WLAN and demonstrates their application through three examples
Intersystem soft handover for converged DVB-H and UMTS networks
Digital video broadcasting for handhelds (DVB-H) is the standard for broadcasting Internet Protocol (IP) data services to mobile portable devices. To provide interactive services for DVB-H, the Universal Mobile Telecommunications System (UMTS) can be used as a terrestrial interaction channel for the unidirectional DVB-H network. The converged DVB-H and UMTS network can be used to address the congestion problems due to the limited multimedia channel accesses of the UMTS network. In the converged network, intersystem soft handover between DVB-H and UMTS is needed for an optimum radio resource allocation, which reduces network operation cost while providing the required quality of service. This paper deals with the intersystem soft handover between DVB-H and UMTS in such a converged network. The converged network structure is presented. A novel soft handover scheme is proposed and evaluated. After considering the network operation cost, the performance tradeoff between the network quality of service and the network operation cost for the intersystem soft handover in the converged network is modeled using a stochastic tree and analyzed using a numerical simulation. The results show that the proposed algorithm is feasible and has the potential to be used for implementation in the real environment
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A medium to long term roadmap for access services on DTV
DTV4All is a project partly funded by the European Commission (CIP ICT Policy Support Programme) to facilitate the provision of access services on digital television across the European Union. Access services literally help their users access the content of television programmes. Important examples of access services for people who are hard of hearing or deaf are subtitles and deaf signing provided with television programmes to allow their users to more fully appreciate the programme dialogue. The primary aim of the DTV4All project is to encourage the roll out of access services on digital television across the EC. To do this the project targets eroding the barriers to the roll out of access services by making clear what these barriers are and how they may be overcome. This paper provides an overview of the progress the project has made in its first two years in meeting this target
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A survey of handover algorithms in DVB-H
Digital Video Broadcasting for Handhelds (DVB-H) is a standard for
broadcasting IP Datacast (IPDC) services to mobile handheld terminals.
Based on the DVB-T standard, DVB-H adds new features such as time
slicing, MPE-FEC, in-depth interleavers, mandatory cell id identifier,
optional 4K-modulation mode and the use of 5 MHz bandwidth in addition
to the usually used 6, 7, or 8 MHz raster. IPDC over DVB-H is proposed
for ETSI to complement the DVB-H standard by combining IPDC and
DVB-H in an end-to-end system. Handover in such unidirectional broadcasting
networks is a novel issue. In the last few years since the birth of
DVB-H technology, great attention has been given to the performance
analysis of DVB-H mobile terminals. Handover is one of the main research
topics for DVB-H in mobile scenarios. Better reception quality and greater
power efficiency are considered to be the main targets of handover
research for DVB-H. New algorithms for different handover stages in
DVB-H have been the subject of recent research and are currently being
studied. Further novel algorithms need to be designed to improve the
mobile reception quality. This article provides a comprehensive survey of
the handover algorithms in DVB-H. A systematic evaluation and categorization
approach is proposed based on the problems the algorithms solve
and the handover stages being focused on. Criteria are proposed and analyzed
to facilitate designing better handover algorithms for DVB-H that
have been identified from the research conducted by the author
Secure and robust multi-constrained QoS aware routing algorithm for VANETs
Secure QoS routing algorithms are a fundamental part of wireless networks that aim to provide services with QoS and security guarantees. In Vehicular Ad hoc Networks (VANETs), vehicles perform routing functions, and at the same time act as end-systems thus routing control messages are transmitted unprotected over wireless channels. The QoS of the entire network could be degraded by an attack on the routing process, and manipulation of the routing control messages. In this paper, we propose a novel secure and reliable multi-constrained QoS aware routing algorithm for VANETs. We employ the Ant Colony Optimisation (ACO) technique to compute feasible routes in VANETs subject to multiple QoS constraints determined by the data traffic type. Moreover, we extend the VANET-oriented Evolving Graph (VoEG) model to perform plausibility checks on the exchanged routing control messages among vehicles. Simulation results show that the QoS can be guaranteed while applying security mechanisms to ensure a reliable and robust routing service
On the performance of densified DVB-H single frequency networks
The broadcasting of TV programmes to mobile phones can be enabled by the newly developed technology called Digital Video Broadcasting-Handheld (DVB-H). Because of the scarcity and cost of frequency resources, frequency reuse needs to be considered when rolling out DVB-H networks. By simulcasting the same content from several transmitters, a Single Frequency Network (SFN) can provide good coverage and good frequency efficiency. In this paper, the performance of densified DVB-H SFN networks is analysed in terms of the coverage probability under different coverage requirements with and without frequency reuse. A dichotomy searching approach is used to determine the optimal cell radius for a cell in a densified DVB-H SFN for a given network topology. Based on the optimal cell radius map and a SFN gain map generated from the simulation results, guidelines are proposed on how to avoid the potential pitfalls in configuring the parameters of a densified DVB-H SFN network and optimise its parameters in terms of minimising the cost of the network for a range of predefined network parameters
OFDM over IEEE 802.11b hardware for telemedical applications
Using a wireless Local Area Network (WLAN) to transmit live high-quality video suitable for a telemedical application presents many challenges, including ensuring sufficient Quality of Service (QoS) for the end-user to be able to make an accurate diagnosis. One of the many problems that exist when developing such a system is the multipath effect caused by the reflections of the transmitted signals on various surfaces including walls, floors, furniture and people. This degrades the signal quality and reduces the amount of available bandwidth and, thus, the quality of the image. Presently, most of Europe is using the IEEE 802.11b hardware for such applications. As an alternative to the existing modulation of 802.11b, Orthogonal Frequency Division Multiplexing (OFDM) is investigated, especially for use inside hospitals. The advantages of using this modulation over IEEE 802.11b hardware for a telemedicine application are examined by means of simulation using three different simulation packages
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CHOICE Internal report I-4: The current status of ICT R&D&I for Chinese Eco-Cities
This report attempts to give a flavour of the current of status of ICT R&D&I for Chinese Eco-cities and thereby provide some insights into the potential of China’s emerging market for Eco-city solutions for EU- China collaborative ICT R&D&I. It addresses Eco-city standards development in China. Evaluation Centres for Eco-City software solutions, the context into which ICT for Chinese Eco-cities fits, Chinese ICT R&D in smart cities, EU-China collaboration in ICT R&D smart cities, EU Member states bilateral cooperation with China on ICT R&D for Eco-cities, Chinese smart city industry alliances, other Chinese industry alliances active in eco-friendly cities, Wuhan Intelligent City, and current concerns related to the market situation for the EU ICT industry. Conclusions are presented followed by recommendations targeted at organisations in EU member states interested in exploring the potential for collaborative ICT R&D&I with Chinese organisations targeted at China’s emerging market for Eco-city solution
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Choice Internal report I-6: Support available for innovation in ICT R&D&I in China: Protecting IPR
This report reviews support available to EU organisations for innovation in collaborative ICT R&D with China. In particular, attention is paid to the extent to which this support addresses ICT IPR related concerns. The report discusses the context of the issues around IPR protection in China, reviews the support for IPR protection in China available to EU organisations at the member state and EU level, support provided by the European Chamber of Commerce in China, guidance from UK Trade & Investment, provides an overview of Chinese industrial associations and centres, and Chinese Science and Technology Bureaus, with an interest in promoting IPR protection and provides some IPR related links. Conclusions are drawn and recommendations made which are targeted at organisations concerned about ICT related IPR protection in China
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