21 resultados
Resultados de la búsqueda
Mostrando 1 - 10 de 21
Ítem Technological Models of Municipal Wireless Networks based on Hybrid WiFi/WiMAX Mesh Networks: a proposal to Colombian Municipalities(Ieee, 2009-10-30) Rodríguez Hernández, Pedro SalvadorThe telecommunications infrastructure citizen-oriented has become a necessity in cities that wish to direct themselves to a new Information Society. One of the technological alternatives for these infrastructures is municipal wireless networks. These municipal wireless networks offer flexibility, speed of installation and less implementation costs for cities. For this reason, it is considered of interest the wider use of wireless networks for the Colombian municipalities, considers that in this environment there is limited budget and low rate of connectivity to broadband networks. This article presents a review of the current state of municipal wireless networks related to the technological aspects, with the intention to propose two technological architectures that may be feasible to implement in the Colombian municipalitiesÍtem Handset based automatic network re-selection system for GSM/GPRS and WiFi(ACM Press, 2008-10-30) Navarro Cadavid, AndrésThis paper presents the results of the development of a handset based automatic network reselection software system, which allows keeping end-to-end connections through semi-transparent handoff on WiFi/GSM-GPRS networks. A description of the developed system's software architecture is given, as well as of the components implemented for it, their functionalities and flow of control, all of which allow the permanent discovery of available networks for the mobile device, their evaluation, selection and switching to the network which offers the best ratings in its performance and operational profile, taking into account the preferences previously configured by the user. The system was developed in Java and C# for different operating systems (WinXP, WinMobile and Linux), and its interoperability has been tested in them. Some of the test scenarios are described and final comments about the tests results are given. Copyright 2008 ACM.Ítem Aplicación de modelos markovianos en sistemas de comunicación móvil celular GSM900*(Universidad Icesi, 2006-07-28) Mantilla F., Javier D.; Monclou S., Alex A.; Navarro Cadavid, Andrés; Camerano F., RafaelEl presente artículo muestra en forma clara que el canal de acceso RACH del sistema GSM (Global System for Mobile) se puede modelar como una cadena de Markov discreta. La teoríade cadenas de Markov se emplea para encontrar el comportamiento de estado estable en el modelo de seis estados planteado por la norma GSM utilizando un lenguaje de alto nivelcomo Matlab, que se emplea para simular el modelo planteado teóricamente. Los resultados de las simulaciones muestran el comportamiento estadístico del proceso de selección yreselección de celda del terminal móvil en el sistema GSM.Ítem Some comparison between propagation models in Cost 2100 Cali Reference Scenario(Universidad Icesi, 2009-08-18T20:25:14Z) Ardila, Carlos Andredy; Mejía Mateus, Duván Javier; Navarro Cadavid, AndrésIn this paper we present results from traditional propagation models like Hata and Walfish Bertoni, implemented in our planning tool, and compare it with results obtained from a commercial tool and also with measurements provided by a local operator. For this experiment, we use the Cost 2100 Cali Reference Scenario.Ítem Método de evaluación y selección de herramientas de simulación de redes(Universidad Icesi, 2011-03-01) García Dávalos, Alexander; Vásquez Mejía, Andrés; Navarro Cadavid, Andrés; Escobar Paz, Lina MarcelaCurrently exists many software tools designed for Network Simulation (both commercial and Open source), situation that present an important decision to make for many researchers: Which tool use for network simulation? This paper proposes a method for evaluation/selection of network simulation tools, based in two key factors: ISO/IEC 9126-1 standard, which defines a quality model for software evaluation; and a cost function, based on values assigned to each one of the six items defined by ISO/IEC 9126-1. This method allows an expert based classification for each of the analyzed tools. We executed a test for NS-2 and NCTUns network simulation tools and obtained results was contrasted with technical reports and scientific articles related with network simulation tools.Ítem Factores que afectan la capacidad en WCDMA y su influencia en la planificación de sistemas de tercera generación(Congreso Iberoamericano de Telematica CITA 2003, 2010-04-14T16:52:19Z) Navarro Cadavid, AndrésIn this paper we use a model that we have developed for CDMA capacity analysis to see how different conditions like propagation model, number of cells and overlapping affect the estimation of CDMA capacity. We will show that the overlapping is not a direct parameter that affect capacity, and there are other factors to consider.Ítem TEST: Serious games for radio communications learning(Ieee, 2013-12-19) Pradilla, Juan VicenteThe game industry has suffered an impressive explosion of popularity, becoming the largest entertainment industry in the world. Games have become a sophisticated extension of the reality and an interesting way for complementing human mind utopias. Training software allows the trainee to immerse in quasi-real controlled situations that could be measured by trainers. In this work we discuss the duality existing between the training based on a serious game and a simple game, based on state of the art technologies. Then we show a training system for telecommunications technicians based on a combination between serious games and "traditional" e-learning platform. We show results for a trial made with a group of students from different disciplines (not only engineering) in order to evaluate learning outcomes using serious games versus other learning approaches. In this paper we discuss such results and make a descriptive statistical analysis of the resultsÍtem Spectrum monitoring low-cost system for developing countries(International Telecommunications Union, 2013-01-01) Vargas Bernal, Leonardo[No hay resumen disponible]Ítem Ajuste estadístico de modelos de propagación de señal usando medidas de la ciudad de Cali(Universidad de Santiago de Cali,, 2012-03-20) Ardila, Carlos AndredyLa dificultad de estimar con exactitud la influencia de los obstáculos, los edificios y el terreno en la pérdida de trayectoria de la señal hace que los modelos de propagación, generalmente utilizados para la planificación de redes inalámbricas externas, en entornos urbanos incluyan algunos elementos empíricos. Por lo tanto, la ecuación final generalmente contiene constantes y coeficientes para los diferentes términos, que se obtienen principalmente a partir del análisis estadístico de mediciones recolectadas durante actividades de drive test en grandes áreas de la ciudad. Desafortunadamente, estos resultados son realmente válidos únicamente para las áreas de la ciudad en las que se obtuvieron y, en el mejor de los casos, para áreas o ciudades similares. Sin embargo, si el nivel de similitud no es suficiente, es necesario realizar ajustes, un proceso que resulta en la formulación de nuevas constantes y nuevos coeficientes. El propósito de este artículo es discutir algunos de los hallazgos obtenidos durante el proceso de ajuste estadístico al escenario de la ciudad de Cali, de los modelos Okumura-Hata, Stanford University Interim (SUI) y Walfisch-Bertoni, usando mediciones.Ítem Simulation and analysis of compressed sensing technique as sampling and data compression and reconstruction of signals using convex programming(Institute of Electrical and Electronics Engineers Inc., 2016-12-14) Navarro Cadavid, Andrés; 21st Symposium on Signal Processing, Images and Artificial Vision, STSIVA 2016The information management has been treated primarily under the Nyquist sampling theory, but it is important to introduce new theories that replace deficiencies of what we know as the classical theory of sampling. These deficiencies create difficulties in data acquisition; this is a problem when large volumes of information are handled, in addition to the higher costs in storage and processing. This article presents the results obtained from the compressed sensing simulation technique applied to two types of signals. The aim of this paper was to simulate a communication system involving the data recovery applying the compressed sensing technique, analyzing sampling rates reduction, measuring the efficiency of the process and the behavior of the technique. The recovery of the signal is made using convex programming and using l1 norm minimization for recover the signals in the time domain. We used the L1Magic toolbox, which is a set of Matlab® functions used to solve optimization problems in this case with the l1eqpd function. As a summary of the obtained results, we checked the efficiency of the compressed sensing technique, minimum average rates for sampling the constructed signals, and the best performance of the technique to recover soft signals compared to non-differentiable signals. Additionally, the recovery results of an audio signal with the compressed sensing technique, by varying the sampling rate and checking the audibility of the signal, are presented. This allowed the testing of this technique in a real scenario, finding a good opportunity for the transmission of audio signals in a more efficient way.
- «
- 1 (current)
- 2
- 3
- »