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Telecommunications (ICT), 2012 19th International Conference on

Date 23-25 April 2012

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Displaying Results 1 - 25 of 115
  • Comparison between rectangular and triangular patch antennas array

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (816 KB) |  | HTML iconHTML  

    In this paper, several designs of micorstip arrays antennas, suitable for wireless communication applications, are presented. This paper demonstrates several shapes of microstrip array antennas, such as rectangular and triangular patch antennas array. Specifically, 4×1, 2×1, and single element of both shapes are designed and simulated by a full wave simulator (IE3d). Moreover, this paper presents a comparison between both rectangular and triangular antenna arrays. Since, the resonance frequency of these antennas is 2.4 GHz; these antennas are suitable for ISM band and WLAN. View full abstract»

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  • Coordinated multipoint power consumption modeling for energy efficiency assessment in LTE/LTE-advanced cellular networks

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (849 KB) |  | HTML iconHTML  

    Chronological developments from first (1G) to state-of-the-art fourth generation (4G) cellular networks have demonstrated remarkable exploits particularly in terms of peak data rate, throughput and spectral efficiency. However, this paper focuses on the energy efficiency (EE) aspect of cellular communications which apparently has been neglected until very recent years. Popular approaches for EE assessment (2G and 3G power consumption models) have been base station deployment strategies and joint management design/optimization techniques. This paper takes a step further to present a coordinated multipoint (CoMP)-enabled mathematical power consumption model for cooperating 4G base stations (eNodeBs) derived via component-oriented modeling technique; a view that a system or equipment comprises numerous energy-consuming components. We utilize the energy consumption rating (ECR) metric for the assessment of energy efficiency and simulations are carried out on the model with or without base station cooperation (BSC). Overall, results indicate on average that considerable energy savings up to 13% can be realized through BSC (CoMP). View full abstract»

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  • OFDM and SCFDE performance comparison for indoor optical wireless communication systems

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (198 KB) |  | HTML iconHTML  

    Single-carrier frequency domain equalization (SCFDE) modulation is a promising technique for highly dispersive channels in broadband wireless communications. Similar to OFDM (orthogonal frequency division multiplexing), SCFDE attach a cyclic prefix (CP) to the transmitted symbol to eliminate inter-carrier interference (ICI) and converts the convolution with the channel to circular convolution. However and unlike OFDM, SCFDE is essentially a single carrier system. Thereby, some of the major OFDM problems, such as high PAPR (peak to average power ratio), are inherently resolved. The high PAPR problem in OFDM and the resulting nonlinear distortions are shown to have significant impact on the performance of indoor optical wireless (OW) systems [1]. Hence, it is the aim of this paper to study the performance of SCFDE for indoor OW systems and compare the performance to OFDM system. It is shown that, indeed, OW SCFDE system has low PAPR as compared to the corresponding OFDM system. However, the performance of OW OFDM systems and their counterpart SCFDE systems are traded off for certain input signal powers and modulation orders. View full abstract»

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  • Code division cooperative identification reader anti-collision protocol in smart RFID systems

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (378 KB) |  | HTML iconHTML  

    In this paper, an anti-collision protocol called code division cooperative identification protocol (CDCIP) is proposed in order to tackle the reader collision problem in smart RFID systems. CDCIP allocates orthogonal sequences to each reader and composes a RFID network. Consequently, it strives to let more than one reader work at the same time and at the same frequency. Eventually, comparing with the traditional protocol, the simulation results show that the proposed protocol offers better average throughput and lower power consumption of the system. View full abstract»

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  • Hardware simulator: Digital block design for time-varying MIMO channels with TGn model B test

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (456 KB) |  | HTML iconHTML  

    A hardware simulator facilitates the test and validation cycles by replicating channel artifacts in a controllable and repeatable laboratory environment. Thus, it makes possible to ensure the same test conditions in order to compare the performance of various equipments. This paper presents new frequency domain and time domain architectures of the digital block of a hardware simulator of MIMO propagation channels. The two architectures are tested with WLAN 802.11ac standard, in indoor environment, using time-varying TGn 802.11n channel model B. After the description of the general characteristics of the hardware simulator, the new architectures of the digital block are presented and designed on a Xilinx Virtex-IV FPGA. Their accuracy and latency are analyzed. View full abstract»

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  • SCORE: Data Scheduling at roadside units in vehicle ad hoc networks

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1621 KB) |  | HTML iconHTML  

    Data Acquisition and delivery in Vehicular Ad hoc Networks (VANETs) is an important topic that has received very little attention. We proposed a system in which roadside units (RSUs) were exploited to satisfy the various requests of VANET users. Our approach uses RSUs as delegates to acquire services from service providers without the users connecting to them. Users' interests range from email messages, news, web downloading, business transactions, multimedia sharing, traffic or weather information, etc... Depending on RSUs to obtain users' data puts a huge load on the RSU network and might lead to a scalability problem, especially with the large number of users in VANETs. In this paper, we build on the approach and propose an RSU scheduling mechanism in which an RSU builds a schedule that is divided into time-slots (TSs). In each TS, all users that are expected to connect to the VANET are specified. Hence, an RSU prepares users' data and caches them during a free TS before the users connect. The users' connection times are derived from observing their actual connections. Our approach was tested using ns2 to assess its efficiency. View full abstract»

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  • Full Diversity Achieving MMSE Frequency-Domain Equalizer for Time-Frequency Interleave Block Transmission

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (211 KB) |  | HTML iconHTML  

    The time-frequency interleave (TFI) diversity method for single carrier block transmission with frequency domain equalization (SC-FDE) has been proposed. For single antenna wireless communication systems, it can provide frequency diversity in frequency selective channels by interleaving and retransmitting. In this article, the linear minimum mean square error (LMMSE) frequency domain equalization structure of TFI block transmission is presented and each diversity branch can be combined with maximum ratio. The diversity gain and bit error rate (BER) performance are analyzed in a theoretical way. Both theoretical analysis and simulation results show that for TFI block transmission with LMMSE FDE, full diversity gain can be obtained. Compared to another full diversity achieving scheme direct sequence spread spectrum (DSSS), a better BER performance can be obtained. View full abstract»

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  • Cognitive interference alignment between small cells and a macrocell

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (249 KB) |  | HTML iconHTML  

    Small cells have attracted large interest lately in the research community, mainly due to easy and quick deployment. In addition, a large number of small cells is in general more energy efficient than macrocells since less power is required to combat path loss and get across the wireless medium. However, in current network configurations these two types of cells have to coexist over the same spectrum because existing cellular systems are mainly based on macrocells and additional bandwidth for small cell deployments is scarce and too expensive to acquire. In this context, this contribution investigates an underlay cognitive communication technique which exploits interference alignment across multiple antennas in order to mitigate the interference of small cell User Terminals (UTs) towards the macrocell Base Station (BS). More specifically, three techniques for aligning interference are investigated, namely static, coordinated and un-coordinated. The system performance is evaluated and compared based on sum-rate capacity, primary rate protection ratio and primary to secondary rate ratio. View full abstract»

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  • A novel approach for emotion classification based on fusion of text and speech

    Page(s): 1 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (511 KB) |  | HTML iconHTML  

    In this paper we design a system that adopts a novel approach for emotional classification from human dialogue based on text and speech context. Our main objective is to boost the accuracy of speech emotional classification by accounting for the features extracted from the spoken text. The proposed system concatenates text and speech features and feeds them as one input to the classifier. The work builds on past research on music mood classification based on the combination of lyrics and audio features. The innovation in our approach is in the specific application of text and speech fusion for emotion classification and in the choice of features, Furthermore, in the absence of benchmark data, a dataset of movie quotes was developed for testing of emotional classification and future benchmarking. The comparison of the results obtained in each case shows that the hybrid text-speech approach achieves better accuracy than speech or text mining alone. View full abstract»

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  • QoS-based resource allocation scheme for Device-to-Device (D2D) radio underlaying cellular networks

    Page(s): 1 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (815 KB) |  | HTML iconHTML  

    Device-to-Device (D2D) communication underlaying cellular network is considered to be a promising resource reuse technique, and it is basically developed for lots of local services. Considering the differences of the quality of services (QoS) between cellular and D2D users, the resource allocation scheme for D2D should flexibly allocate resource for D2D, rather than limiting one D2D user to share resource with one cellular user. A QoS-based resource allocation scheme for D2D users in the context of an OFDM-based air interface is proposed. This scheme exploits the QoS information, especially the rate target of users, to allocate sufficient resource as need. In addition, the system efficiency can be improved as the proposed resource allocation scheme always select the most efficient resource for D2D users. Numerical results corroborate that the proposed scheme can fulfill D2D user's QoS requirements effectively, and meanwhile accommodate different QoS requirements flexibly. View full abstract»

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  • Cooperative beamforming in cognitive radio network with hybrid relay

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (257 KB) |  | HTML iconHTML  

    In this paper we investigate the cooperative beamforming in cognitive radio network (CRN) composed of a primary network (PN) and a secondary network (SN). In the SN, the transmitter has to communicate with the receiver with the help of the hybrid relays which use cooperative beamforming to retransmit data. The relays will select amplify-and-forward (AF) or decode-and-forward (DF) according to the signal to interference pulse noise ratio (SINR). The aim of this paper is to maximize the received SINR in the SN with different power constraints and the QoS requirement of the primary user (PU). Numerical results compare the performance of the SN between relays with beamforming and relays without beamforming which indicates that the gap between them is related to the maximum interference power at primary destination, while is irrelevant to maximum the total transmitted power of the relays. Besides there is a tradeoff between the performance of the SN and the number of the relays. View full abstract»

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  • A spatial diversity reception of binary signal transmission over Rayleigh fading channels with correlated impulse noise

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1240 KB) |  | HTML iconHTML  

    A Class-A density is well known to model interference, which is impulsive by nature. This model is expressed as a weighted infinite linear combination of Gaussian densities with different variances. The extension of this model for multiple receiving antennas is currently limited to two antennas. An algebraic extension leads to a multivariate Class-A density, which can be used for an arbitrary number of antennas. In this paper, we consider the design of optimum diversity combining for Rayleigh fading channels in the presence of Class-A interference. Since recent studies show a significant level of noise correlation in some wireless systems, we begin with a correlated multivariate Class-A model. Then, we show that the optimum combiner can be approximated by a maximum ratio combiner (MRC) preceded by noise decorrelators, which has a much lower complexity compared with the optimum one. When the interference is uncorrelated, we prove that the conventional MRC approximates the optimum combining. View full abstract»

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  • Non-binary LDPC Coded Orthogonal Modulation with Non-coherent Detection

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (216 KB) |  | HTML iconHTML  

    A symbol-level iterative decoding scheme of non-binary LDPC coded orthogonal modulation with non-coherent demodulation is presented. Compared to the conventionally used bit interleaved coded modulation with iterative decoding (BICM-ID), the proposed scheme directly combine LDPC codes over GF(q) (q>;2) with M-ary orthogonal modulation together. The soft input and soft output demodulation with non-coherent detection is discussed to obtain the symbol level soft decision information to initialized the iterative decoding process of non-binary LDPC codes. Simulation-oriented method is employed to find optimal LDPC codes of a certain kind. Results indicate our proposed scheme owns a better performance than BICM-ID and lower computational complexity to achieve a soft input and soft output demodulation. View full abstract»

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  • Modeling electrocardiogram using Yule-Walker equations and kernel machines

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (148 KB) |  | HTML iconHTML  

    One may monitor the heart normal activity by analyzing the electrocardiogram. We propose in this paper to combine the principle of kernel machines, that maps data into a high dimensional feature space, with the autoregressive (AR) technique defined using the Yule-Walker equations, which predicts future samples using a combination of some previous samples. A pre-image technique is applied in order to get back to the original space in order to interpret the predicted sample. The relevance of the proposed method is illustrated on real electrocardiogram from the MIT benchmark. View full abstract»

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  • Performances of low profile dipole antenna AMC-based surface using metamaterials structures

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (501 KB) |  | HTML iconHTML  

    Artificial Magnetic Conductors (AMCs), a real version of Perfect Magnetic Conductors (PMCs), are widely used to replace surfaces of high impedance. Based on unit cells of Multiple Split-Ring Resonators (MSRRs) that are printed on low-cost dielectric grounded substrate, AMCs are employed as a ground plane for antennas. In this paper, the performance of a low profile dipole antenna positioned above a planar AMC surface is examined. The characteristics of the AMC return loss are initially investigated at the resonant frequency of 2.4 GHz. Two arrays having 49 and 81 MSRR unit cells are then simulated and modeled with the dipole antenna placed above. The results are of great importance as the directivity reaches 6 dB for the configuration of 9 × 9 unit cells. This confirms that the MSRR can perfectly replace the conventional ground plane antenna in order to improve the gain and the directivity of their radiations. View full abstract»

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  • Error sources in COTS WSN platforms for impulsive signal acquisition applications

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (495 KB) |  | HTML iconHTML  

    In this work we present a detailed discussion of the various sources of errors in commercial off the shelf (COTS) wireless sensor node (WSN) platforms through a series of experiments. These COTS WSNs are programmed using the TinyOS 2.x standard components and interfaces. The experimental setup is used to record an impulsive acoustic signal from several sensor nodes' microphones and send to the base-station for processing. The Flooding Time Synchronization Protocol (FTSP) was used, and a special MATLAB interfacing code was written to analyze and present the errors within this acquisition setup. It was found that there are at least 4 error sources that can dramatically degrade the signal acquisition due to the fact that standard TinyOS components are not suitable for medium/high sampling frequency applications. View full abstract»

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  • Third-order complex amplitudes tracking loop for slow fading channel estimation

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (997 KB) |  | HTML iconHTML  

    This paper deals with channel estimation over a flat fading Rayleigh channel with Jakes' Doppler Spectrum. Many estimation algorithms exploit the time-domain correlation of the channel by employing a Kalman filter based on a first-order (or sometimes second-order) approximation of the time-varying channel. In the low-variation channel scenario, generally speaking, a well-chosen higher order estimator can perform better than a lower order one (Ros et al., [1] [2]). Based on this fact, we propose a third-order tracking loop estimator inspired by the principle of the phase-locked loop (PLL). The proposed estimator has a less complex structure compared to the Kalman-based estimators. In addition, the mean-squared-error (MSE) of the proposed estimator is studied, as well as the parameter optimization with the aim of minimizing the MSE. The closed form expression of the optimal MSE is given and validates the interest of our approach. View full abstract»

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  • Indoor localization using polar intervals in wireless sensor networks

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (526 KB) |  | HTML iconHTML  

    Wireless sensor networks are networks composed of a large number of distributed sensors, connected via wireless links. This paper deals with the problem of localization in wireless sensor networks. Such a problem becomes challenging in indoor environments, where signals of Global Positioning Systems are no more reliable. In this paper, the localization problem is defined using connectivity measurements. The proposed technique consists thus of estimating unknown sensors positions using known position information of neighboring sensors. The estimation is then performed using polar intervals. The estimated positions are thus two-dimensional intervals defined in some polar coordinates system. Using intervals, the proposed approach performs an outer estimation of the solution, leading to estimates covering for sure the actual positions of the sensors. View full abstract»

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  • Improved performance analysis based on a novel hybrid access algorithm in femtocell networks

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (198 KB) |  | HTML iconHTML  

    As the most potential way to improve the overall performance of the next generation wireless networks, femtocell has attracted much attention from vendors. To femtocell, hybrid access mode is a comprise access mode that operates between close access mode and open access mode. With this kind of access mode, not only the pre-registered users are able to access it, un-registered users could also gain benefits as long as there is available resources. In this paper, we propose a novel access control algorithm based on hybrid access mode. Simulation results show that this algorithm can decrease the outage rate of macro users without causing too much signaling overhead. View full abstract»

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  • An upper bound for the total number of options to implement an SDR multi-standard system

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (441 KB) |  | HTML iconHTML  

    The design of future multi-standard systems is very challenging. Flexible architectures that exploit common aspects between the different set of standards cohabiting in the device offer promising solutions. In this paper, we adopt the theory of graphs and particularly the study of directed hypergraphs, which helps in providing a theoretical view of the graph structure of the multi-standard system. This graph description exhibits all the alternatives capable of implementing the system. On the other hand, we further provide in this paper an exponential upper bound for the total number of options which are capable of implementing a multi-standard design. View full abstract»

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  • Cache management using temporal pattern based solicitation for content delivery

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (637 KB) |  | HTML iconHTML  

    Caching is an effective technique to improve the quality of streaming multimedia services. In this paper, we propose a novel content caching scheme referred as “Cache Management using Temporal Pattern based Solicitation” (CMTPS), to further minimize both service delays and load in the network for Video on Demand (VoD) applications. CMPTS is based on the analysis of clients' requests over passed time intervals to predict the contents that will be solicited in the near future. By means of experimental tests, the CMTPS protocol is evaluated. The obtained results show that CMTPS outperforms LRU, in terms of peak traffic reduction and number of cache hits. View full abstract»

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  • Characterisation and verification of an FPGA signal generator for spectrally efficient wireless FDM

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (4071 KB) |  | HTML iconHTML  

    For research and development in computationally intensive bandwidth efficient Frequency Division Multiplexing (FDM) systems, it is generally preferable to implement test systems in hardware. This has the benefit of speed improvement over simulation and enables the generation and evaluation of real signals. This paper describes a system implementation of a versatile signal generator featuring high speed and large bit-depth Digital to Analogue Converters (DACs), RAM storage and an Field Programmable Gate Array (FPGA) to perform multi-carrier real time signal generation. Since the validity of such generated signals requires qualification by characterisation of the generating hardware, this paper describes a measurement methodology and presents results and comparison to vendor specification. View full abstract»

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  • Offline multi-class flow allocation in MPLS networks using a distributed multi-objective genetic algorithm

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (578 KB) |  | HTML iconHTML  

    The explosion of Internet-like data traffic and services (voice, video, multiplayer games, download, etc.) is fueling the demands for higher mobile telecom network capacities. Traditionally, mobile operators are used to add new transmission links and equipments to satisfy the traffic increase. However, this solution is firstly expensive in terms of capital and operation and secondly inadequate with the new telecommunication generations as 3G and 4G. In this paper, we propose a traffic engineering based approach to maximize the network usage. Based on an advanced Multi-Objective, Multi-Population Genetic Algorithm, we propose an offline distribution of Label Switch Paths (LSPs) that takes into consideration the scalability of the network, the Quality of Service (QoS) constraints for 4 Classes of Service (CoS) and recovery path to ensure high network availability. Congestion reduction, bandwidth optimization and other objectives have been combined to offer the network planner an optimal network management. View full abstract»

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  • Towards a generic trust management model

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (263 KB) |  | HTML iconHTML  

    Trust is one of the fundamental security concepts since it provides network collaborating entities with a mean to counter their uncertainty. Trust is generally integrated into existent security frameworks in order to add a security level to entities collaborations through the use of trust relations. Besides, benefiting from trust relations implies establishing them, updating them when needed and revoking them if necessary. Unfortunately, using trust can be a hard task since it has to cope with subjectivity and may change according to the involved entities. A formal model can be used to alleviate this problem. One way to formalize trust concept is the use of trust management. This latter allows unifying and standardizing trust as well as all its inherent concepts. It provides needful basis for trust establishment, update and revocation. Different dedicated trust management models were proposed corresponding to existing specific needs. Our main contribution in this paper is then, the proposition of a generic trust management model suitable to the most communication domains and needs. This model is based on the main trust concepts such as recommendations and reputations as well as the main properties such as permanence, transitivity and asymmetry. View full abstract»

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  • Localization in large scale wireless sensor networks

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1569 KB) |  | HTML iconHTML  

    Wireless Sensor Networks facilitate monitoring physical environments with improved accuracy. Localization has been a major challenge in such networks because without finding the position of the sensor that is reporting sensed data, the reported data will not be useful. In this paper, we survey some of the existing localization techniques and propose a new algorithm for large scale networks that minimizes both localization error and power consumption. We also evaluate the performance of these algorithms using the network simulator (NS-2) measuring several metrics such as energy and localization error while varying a number of simulation parameters such as the number of sensors, the area size, etc. Results show that significant enhancement is obtained with the proposed algorithm. View full abstract»

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