New technique combining the Tone Reservation method with Clipping technique to reduce the Peak-to-Average Power Ratio

Nonlinear distortions and impairments appear in multicarrier signal with high fluctuations when amplified by a Radio Frequency Power Amplifier (RF PA). Clipping (CL) technique offers a simple way to reduce these fluctuations in Orthogonal Frequency Division Multiplexing (OFDM) Technique, but may degrade seriously the transmission quality. This is why the new mobile standards propose other methods, like the Tone Reservation (TR) technique in the Digital Video Broadcasting-Terrestrial (DVB-T), that reduce the Peak-to-Average Power Ratio (PAPR) without reaching optimal performances. This paper deals with how we can use the TR technique, which exploits null sub-carriers for generating corrective signal, in combining to CL technique in order to improve PAPR reduction without data loss. Also, we show some comparison results on the PAPR reduction obtained with proposed scheme and other techniques. Experiments using a simulated example on a complete WiMax 802.16e transmitter have been made in order to investigate the PAPR reduction performances on presence of the non-linear Power Amplifier model based on gain compression response and phase distortion

Performance Analysis of Synthetic Mobility Models and Mobile Ad Hoc Routing Protocols

Routing protocols heavily influenced by the node motion applied. Many performance analyses are already done with a lot of flaws. But, they do not look to all influenced constraints. Sometimes, they evaluate routing protocols without taken into consideration mobility models. They often analyze them using one routing protocol. Whereas, Simulation time employed is too short. It mainly impacts performance metrics of many mobility models. Or usually, simulation area used is small. It influences the number of packets received. In this study, we aim to summarize all these several parameters into 90 different scenarios with an average of 1350 simulated files. We will combine some well-known mobility models with the most prominent mobile Ad hoc routing protocols in order to analyze their accurate behaviors in one experimental synthesis paper. That shows results of three performance metrics combined with five mobile ad hoc routing protocols under three synthetic mobility models. All these parameters are applied to two dissimilar simulation areas, a small one with (220 m x 220 m) and a large one with (1020 m x 1020 m). Basing on one exhaustive analysis with all these details like this paper; leads to well understand the accurate behaviors of routing protocols and mobility models used. By displaying the ability of every routing protocol to deal with some topology changes, as well as to ensure network performances

Multi-Criteria Vertical Handover Comparison between Wimax and Wifi

In next generation wireless networks, the most tempting feature is the ability of the user to move smoothly over different access networks regardless of the network access technology. In this paper we study the benefit of Multiple Attribute Decision Making (MADM) strategies for network selection. We compare three of these methods naming Simple Additive Weighting (SAW), Multiplicative Exponential Weighting (MEW) and Technique for Order Preference by Similarity to an Ideal Solution (TOPSIS) in a realtime ns-3 simulation. Analytic Hierarchy Process (AHP) provides the weights of attributes which allow the comparison in different types of applications. Therefore, we propose a performance evaluation model with a reconfiguration of AHP parameters used in the literature. Simulation results show that the proposed parameters provide an improvement of Delay and offer allowable Packet loss in different types of applications

Smart Collection of Real-Time Vehicular Mobility Traces

Mobility trace techniques makes possible drawing the behaviors of real-life movement which shape wireless networks mobility whereabouts. In our investigation, several trace mobility models have been collected after the devices’ deployment. The main issue of this classical procedure is that it produces uncompleted records due to several unpredictable problems occurring during the deployment phase. In this paper, we propose a new procedure aimed at collecting traces while deployment phase failures are avoided, which improves the reliability of data. The introduced procedure makes possible the complete generation of traces with a minimum amount of damage without the need to recover mobile devices or lose them, as it is the case in previous mobility traces techniques. Based on detecting and correcting all accidental issues in real time, the proposed trace scanning offers a set of relevant information about the vehicle status which was collected during seven months. Furthermore, the proposed procedure could be applied to generate vehicular traces. Likewise, it is suitable to record/generate human and animal traces. The research outcomes demonstrate the effectiveness and robustness of the smart collection algorithm based on the proposed trace mobility model

Diacritical Language OCR Based on Neural Network: Case of Amazigh Language

AbstractDocument paper conversion into electronic format has become indispensable task in many areas, especially for digitizing and translating printed texts. In this context, several approaches have been studied focusing mainly on character recognition for diacritic-free languages. However in this paper, we are interested in the Amazigh language transcribed in Latin, distinguished by its diacritical characters. Thus, we propose to use a system based on neural networks, and to study its behavior against this type of characters

Flexible synthetic mobility modeling to discover trajectories for complex areas of mobile wireless networks

El modelado de movilidad es uno de los pilares más influyentes para mejorar el rendimiento de las redes inalámbricas. Comprender las características de movilidad es relevante para el diseño y análisis de esquemas de movimiento adecuados para cualquier red. Hasta ahora, se ha sugerido una variedad de modelos de movilidad de entidades que no tienen en cuenta todas las características de los movimientos de la vida real (tiempo, espacio, entorno). Para obtener un modelo mejorado que supere tales limitaciones, en este documento se propone un nuevo modelo híbrido de movilidad de entidad sintética, denominado modelo de movilidad Maze (MzMM). También tiene en cuenta el historial de la línea de tiempo, las dependencias espaciales y las restricciones geográficas. Al mismo tiempo, respeta las leyes del movimiento para reflejar escenarios reales utilizando un mecanismo de descubrimiento flexible, donde permite que los nodos lleguen a destinos predefinidos siguiendo las trayectorias más apropiadas en presencia de varios obstáculos. Este enfoque permite que los nodos móviles se muevan correctamente incluso en presencia de múltiples restricciones de movilidad. La importancia de esta investigación es que el nuevo enfoque considera una combinación realista de parámetros para lograr un modelo de movilidad flexible y robusto que se pueda aplicar para la movilidad autónoma o humana, incluso en entornos complejos para proporcionar rendimientos optimizados para redes, como lo demuestra su alta Resultados de rendimiento

Deep Validation of Spatial Temporal Features of Synthetic Mobility Models

This paper analyzes the most relevant spatial-temporal stochastic properties of benchmark synthetic mobility models. Each pattern suffers from various mobility flaws, as will be shown by the models’ validation. A set of metrics is used to describe mobility features, such as the speed decay problem, the density wave phenomenon, the spatial node distribution, and the average neighbor percentage. These metrics have already been validated for the random waypoint mobility model (RWPMM), but they have not yet been verified for other mobility patterns that are most frequently used. For this reason, this investigation attempts to deeply validate those metrics for other mobility models, namely the Manhattan Grid mobility, the Reference Point Group mobility, the Nomadic Community mobility, the Self-Similar Least Action Walk, and SMOOTH models. Moreover, we propose a novel mobility metric named the “node neighbors range„. The relevance of this new metric is that it proves at once the set of outcomes of previous metrics. It offers a global view of the overall range of mobile neighbors during the experimental time. The current research aims to more rigorously understand mobility features in order to conduct a precise assessment of each mobility flaw, given that this fact further impacts the performance of the whole network. These validations aim to summarize several parameters into 18,126 different scenarios with an average of 486 validated files. An exhaustive analysis with details like those found in this paper leads to a good understanding of the accurate behaviors of mobility models by displaying the ability of every pattern to deal with certain topology changes, as well as to ensure network performances. Validation results confirm the effectiveness and robustness of our novel metric

Investigations sur les performances de la méthode TR avec écrêtage pour la réduction des fluctuations dans les modulations mutliporteuses

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