| 1. |
- Arkoulis, Stamatios, et al.
(författare)
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Misbehaviour Scenarios in Cognitive Radio Networks
- 2010
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Ingår i: Future Internet. - : Future Internet Editorial Office. - 1999-5903. ; 2:3-4, s. 212-237
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Forskningsöversikt (refereegranskat)abstract
- Recent advances in the fields of Cognitive Radio and the proliferation of open spectrum access promise that spectrum-agile wireless communication will be widespread in the near future, and will bring significant flexibility and potential utility improvements for end users. With spectrum efficiency being a key objective, most relevant research focuses on smart coexistence mechanisms. However, wireless nodes may behave selfishly and should be considered as rational autonomous entities. Selfishness, pure malice or even faulty equipment can lead to behavior that does not conform to sharing protocols and etiquette. Thus, there is a need to secure spectrum sharing mechanisms against attacks in the various phases of the sharing process. Identifying these attacks and possible countermeasures is the focus of this work.
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| 2. |
- Polyzos, George, et al.
(författare)
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ASPECTS : Agile spectrum security
- 2011
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Konferensbidrag (refereegranskat)abstract
- Cognitive Radio (CR) promises to provide better spectrum utilization and increase the availability of (on demand) broadband access to the Network of the Future. CR relies on devices that can sense their (radio) environment, understand it, and model it, so that they can exploit the spectrum through appropriate transmission parameters (in the space, time, and frequency domains) that do not interfere with legacy and/or licensed devices using the same spectrum in the same general area. According to the CR paradigm, the use of the spectrum that is not used by primary (licensed) users is opportunistic. Secondary users sense the spectrum and decide to use it on their own, possibly following additional rules and protocols. Because multiple such CR devices (secondary users) can find themselves in the same area and compete for the same spectrum, the question that arises is whether these devices behave fairly and appropriately. The opportunities are there for competing CR devices to try to grab more resources through the spreading of misinformation and impersonation of licensed devices.
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| 3. |
- Schumacher, Jens, et al.
(författare)
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Providing an User Centric Always Best Connection
- 2010
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Konferensbidrag (refereegranskat)abstract
- Although Quality of Experience (QoE) is perceived as a subjective measure of a user’s experience, it is the only measure that actually counts to a user of a service. It is essential to identify, quantify and ultimately improve the perception of QoE for a user. The PERIMETER project improves the user’s experience by identifying a more user-centric network selection, based on QoE calculations and user preferences. PERIMETER defines a generic QoE model which forms the basis for QoE signalling and QoE based content adaptation support. This paper provides an insight into how user centric seamless mobility is being achieved by PERIMETER, beginning with an explanation of QoE and the need for preferences. Next, more details of the complete system, including QoE management, user feedback and the final delivery, are provided. Finally, an outlook is given on PERIMETER’s future plans and its contributions to research in the Future Internet.
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| 4. |
- Strelnikov, Boris, et al.
(författare)
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Sounding rocket project PMWE for investigation of polar mesosphere winter echoes
- 2021
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Ingår i: Journal of Atmospheric and Solar-Terrestrial Physics. - : Elsevier BV. - 1364-6826 .- 1879-1824. ; 218
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Tidskriftsartikel (refereegranskat)abstract
- A first sounding rocket campaign dedicated to investigate the creation mechanism of Polar Mesosphere Winter Echoes (PMWE) was conducted in April 2018 from the north Norwegian Andøya Space Center (69 °N, 16 °E). Two instrumented sounding rockets were launched on 13th and 18th of April under PMWE and non-PMWE conditions, respectively. In this paper we give an overview of the PMWE sounding rocket mission. We describe and discuss some results of combined in situ and ground-based measurements which allow to verify existing PMWE theories. Our measurements ultimately show that: a) polar winter mesosphere is abounded with meteor smoke particles (MSP) and intermittent turbulent layers, b) all PMWE observed during this campaign can be explained by neutral air turbulence, c) turbulence creates small-scale structures in all D-region constituents, including free electrons; d) MSP ultimately influence the radar volume reflectivity by distorting the turbulence spectrum of electrons, e) the influence of MSP and of background electron density is just to increase SNR.
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