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Ítem 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 Sistema pervasivo de computación urbana para entornos turísticos en el Zoológico de Cali(Instituto Tecnológico Metropolitano, 2010-11-04) Navarro Cadavid, AndrésEste artículo presenta el proceso de desarrollo de un sistema pervasivo de computación urbana para entornos turísticos, en el marco del proyecto “Sistema pervasivo de computación urbana (Urb@na) para entornos turísticos utilizando servicios basados en localización Wi-Fi y sensores urbanos” Repasa los estudios previos para el proyecto, los criterios de diseño y algunos aspectos técnicos de la propuesta. Palabras claves: Sensores urbanos, dispositivos móviles, RFID, computación ubicua, computación urbanaÍtem 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 of vertical handover algorithms with NCTUns(Society for Modeling and Simulation International, 2010-01-01) Navarro Cadavid, AndrésThis paper presents the simulation of Vertical Handover Algorithms (VHA) using NCTUns and tested them on scenarios with WiFi/GPRS or WiFi/WiMAX Mobile networks: The first evaluates parameters such as the network bandwidth, economic cost of the connection and the mobile node mobility and uses a cost function toevaluate candidate networks. The second one is based on application requirements such as bandwidth, latency and % packet loss rate. The third one organizes the nodes connections to balance the load on connection points, optimize battery consumption, or both. We developed several scripts in C and PERL language for inclusion in the tool like other components and use a NCTUns API to communicate with the simulation engine. In simulation scenario we use the multi-interface node for Intelligent Transportation System (ITS) networks or a node for each technology, but they behave as a single node with multiple interfaces. Simulations results are used to analyze the VHAs performance measuring handover delay, number of avoided handovers and computational cost of the algorithms.