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showing 10 items of 3931 documents

Rateless Codes Performance Analysis in Correlated Channel Model for GEO Free Space Optics Downlinks

2012

Settore ING-INF/03 - TelecomunicazioniFree Space Optics (FSO) technologies for satellite communications offer several advantages: wide bandwidth high rate capability immunity to electromagnetic interference and small equipment size. Thus they are suitable for inter-satellite links deep space communications and also for high data rate ground-to-satellite/satellite-to-ground communications. Nevertheless FSO links suffer impairments that cause power signal degradation at the receiver. Scattering and absorption cause power signal attenuations predictable by suitable deterministic models. Optical turbulence causes random irradiance fluctuations which can generate signal fading events and can thereby only be predicted by statistical models. Attenuation and fading events can corrupt FSO links and so it would be recommended to add mitigation error codes on the communication link. FSO channel can be described as an erasure channel: fading events can cause erasure errors. We have identified in rateless codes (RCs) a suitable solution to be employed in FSO links. RCs do not need feedback and they add a redundant coding on the source data that allows the receiver to recover the whole payload despite erasure errors. We implemented two different of rateless codes: Luby Transform (LT) and Raptor. We analyzed their performances on a simulated turbulent GEO FSO downlink (1 Gbps - OOK modulation) at a 106 μm wavelength and for different values of zenith angles. Assuming a plane-wave propagation and employing Hufnagel-Valley we modeled the downlink using: 1) a temporal correlated channel model based on Gamma-Gamma probability distribution and 2) an irradiance covariance function that we converted on a time function using Taylor frozen eddies hypothesis. Our new channel model is able to simulate irradiance fluctuations at different turbulence conditions as it will be shown in the full paper. We will also report performance results of LT and Raptor codes at overhead range varying between 0 and 50% and for different values of source packets.Settore ING-INF/01 - Elettronica
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Random access with repeated contentions for emerging wireless technologies

2017

In this paper we propose ReCo, a robust contention scheme for emerging wireless technologies, whose efficiency is not sensitive to the number of contending stations and to the settings of the contention parameters (such as the contention windows and retry limits). The idea is iterating a basic contention mechanism, devised to select a sub-set of stations among the contending ones, in consecutive elimination rounds, before performing a transmission attempt. Elimination rounds can be performed in the time or frequency domain, with different overheads, according to the physical capabilities of the nodes. Closed analytical formulas are given to dimension the number of contention rounds in order…

Settore ING-INF/03 - Telecomunicazionibusiness.industryOrthogonal frequency-division multiplexingComputer scienceComputer Science (all)020206 networking & telecommunications02 engineering and technologycomputer science (all); electrical and electronic engineering; binary alloys0202 electrical engineering electronic engineering information engineeringWireless020201 artificial intelligence & image processingElectrical and Electronic EngineeringbusinessRandom accessComputer networkIEEE INFOCOM 2017 - IEEE Conference on Computer Communications
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A Novel Recruitment Policy to Defend against Sybils in Vehicular Crowdsourcing

2021

Vehicular Social Networks (VSNs) is an emerging communication paradigm, derived by merging the concepts of Online Social Networks (OSNs) and Vehicular Ad-hoc Networks (VANETs). Due to the lack of robust authentication mechanisms, social-based vehicular applications are vulnerable to numerous attacks including the generation of sybil entities in the networks. We address this important issue in vehicular crowdsourcing campaigns where sybils are usually employed to increase their influence and worsen the functioning of the system. In particular, we propose a novel User Recruitment Policy (URP) that, after extracting the participants within the event radius of a crowdsourcing campaign, detects …

Settore ING-INF/05 - Sistemi Di Elaborazione Delle InformazioniAuthenticationEvent (computing)business.industryComputer sciencecomputer.internet_protocolComputerSystemsOrganization_COMPUTER-COMMUNICATIONNETWORKSCrowdsourcingComputer securitycomputer.software_genreDomain (software engineering)Random forestCrowdsourcing; Proximity Graph; Sybil detection; Trust and Truthfulness; Vehicular Social NetworkCrowdsourcing Proximity Graph Sybil detection Trust and Truthfulness Vehicular Social NetworkGraph (abstract data type)RADIUSbusinesscomputer
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Secure random number generation in wireless sensor networks

2011

The increasing adoption of wireless sensor networks as a flexible and inexpensive tool for the most diverseapplications, ranging from environmental monitoring to home automation, has raised more and more atten-tion to the issues related to the design of specifically customized security mechanisms. The scarcity ofcomputational, storage, and bandwidth resources cannot definitely be disregarded in such context, and thismakes the implementation of security algorithms particularly challenging. This paper proposes a securityframework for the generation of true random numbers, which are paramount as the core building blockfor many security algorithms; the intrinsic nature of wireless sensor nodes …

Settore ING-INF/05 - Sistemi Di Elaborazione Delle InformazioniLeader electionleader election random numbers generation wireless sensor networksRandom number generationbusiness.industryComputer scienceDistributed computingKey distribution in wireless sensor networksTrue random numbers generatorRobustness (computer science)Mobile wireless sensor networknetwork securityWirelessbusinesswireless sensor networksWireless sensor networkRandomnessComputer Science::Cryptography and SecurityComputer network
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A TRNG Exploiting Multi-Source Physical Data

2010

In recent years, the considerable progress of miniaturization and the consequent increase of the efficiency of digital circuits has allowed a great diffusion of the wireless sensor network technology. This has led to the growth of applications and protocols for applying these networks to several scenarios, such as the military one, where it is essential to deploy security protocols in order to prevent opponents from accessing the information exchanged among sensor nodes. This paper analyzes security issues of data processed by the WSN and describes a system able to generate sequences of random numbers, which can be used by security algorithms and protocols. The proposed True Random Number G…

Settore ING-INF/05 - Sistemi Di Elaborazione Delle InformazioniRandom number generationbusiness.industryNetwork securityComputer scienceDistributed computingNode (networking)Cryptographic protocolTrusted third partyKey distribution in wireless sensor networksWireless Sensor Networks Random Number Generator Network SecurityNISTbusinessWireless sensor networkComputer network
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A genetic algorithm for the design of a fuzzy controller for active queue management

2003

Active queue management (AQM) policies are those\ud policies of router queue management that allow for the detection of network congestion, the notification of such occurrences to the\ud hosts on the network borders, and the adoption of a suitable control\ud policy. This paper proposes the adoption of a fuzzy proportional\ud integral (FPI) controller as an active queue manager for Internet\ud routers. The analytical design of the proposed FPI controller is\ud carried out in analogy with a proportional integral (PI) controller,\ud which recently has been proposed for AQM. A genetic algorithm is\ud proposed for tuning of the FPI controller parameters with respect\ud to optimal disturbance rej…

Settore ING-INF/05 - Sistemi Di Elaborazione Delle InformazioniRouterQueue management systemComputer sciencePID controllerFuzzy control systemRandom early detectionTCP Congestion ControlActive queue managementNetwork CongestionFuzzy logicComputer Science ApplicationsHuman-Computer InteractionNetwork congestionControl and Systems EngineeringControl theoryElectrical and Electronic EngineeringTail dropActive Queue ManagementSoftwareFuzzy Controllers.Information SystemsIEEE Transactions on Systems, Man and Cybernetics, Part C (Applications and Reviews)
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A Study on Classification Methods Applied to Sentiment Analysis

2013

Sentiment analysis is a new area of research in data mining that concerns the detection of opinions and/or sentiments in texts. This work focuses on the application and the comparison of three classification techniques over a text corpus composed of reviews of commercial products in order to detect opinions about them. The chosen domain is about "perfumes", and user opinions composing the corpus are written in Italian language. The proposed approach is completely data-driven: a Term Frequency / Inverse Document Frequency (TFIDF) terms selection procedure has been applied in order to make computation more efficient, to improve the classification results and to manage some issues related to t…

Settore ING-INF/05 - Sistemi Di Elaborazione Delle InformazioniText corpusNaive Bayes classifierComputer sciencebusiness.industrySentiment analysisTF-IDFSentiment Classificationcomputer.software_genreClass Association RulesDomain (software engineering)Naive Bayes classifierRandom indexingArtificial IntelligenceSelection (linguistics)One-class classificationArtificial intelligenceRandom Indexingbusinesstf–idfcomputerNatural language processing
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The Reciprocal Influences among Motivation, Personality Traits, and Game Habits for Playing Pokémon GO

2018

This article reports a study exploring motivations of Pokémon Game use, individual differences related to personality traits, and game habits. First, it analyzed Pokémon GO motivations through exploratory factor analysis (EFA) by administering online the Pokémon GO Motivational Scale to a group of Italian gamers (N = 560). Successively, a Confirmatory Factor Analysis (CFA) was conducted testing three factorial models of Pokémon Game motivations on a selected random sample (N = 310). Results showed a three-factor model of Pokémon GO Game motivations (i.e. Personal Needs, Social Needs and Recreation), accounting for 68.9% of total variance plus a general higher order factor that best fits the…

Settore M-PSI/01 - Psicologia GeneraleRandom sampleHuman Factors and ErgonomicsConfirmatory factor analyses (CFA)Individual Difference0502 economics and businessMultivariant analysiPsychology0501 psychology and cognitive sciencesBig Five personality traitsPersonality traitComputingMilieux_MISCELLANEOUS050107 human factorsMotivationThree-factors model05 social sciencesSettore M-PSI/03 - PsicometriaComputer Science ApplicationsHuman-Computer InteractionExploratory Factor Analysis (EFA)Factorial model[SCCO.PSYC]Cognitive science/Psychology050211 marketingPsychologySocial psychologyReciprocal
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Random Stability of an Additive-Quadratic-Quartic Functional Equation

2010

Using the fixed point method, we prove the generalized Hyers-Ulam stability of the following additive-quadratic-quartic functional equation f(x+2y)+f(x−2y)=2f(x+y)+2f(−x−y)+2f(x−y)+2f(y−x)−4f(−x)−2f(x)+f(2y)+f(−2y)−4f(y)−4f(−y) in complete random normed spaces.

Settore MAT/05 - Analisi MatematicaApplied Mathematicslcsh:MathematicsDiscrete Mathematics and Combinatoricslcsh:QA1-939AnalysisRandom normed space fixed point generalized Hyers-Ulam stability additive-quadratic-quartic functional equationJournal of Inequalities and Applications
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On Edelstein Type Multivalued Random Operators

2014

The purpose of this paper is to provide stochastic versions of several results on fixed point theorems in the literature.

Settore MAT/05 - Analisi MatematicaCommon fixed pointMultivalued mappingsRandom operatorMetricspace2000 AMS Classification:47H0947H1047H4054H2560H25multivalued mappingmetric space.common fixed pointrandom operator
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